GIFT OF MICHAEL REESE A TEXT-BOOK OF ORGANIC CHEMISTRY RICHTER ANSCHOTZ SMITH VOLUME II OF THIS WORK, THE AROMATIC SERIES, is IN RAPID PREPARATION AND WILL BE PUBLISHED DURING 1899. VICTOR VON RICHTER'S V ORGANIC CHEMISTRY OR CHEMISTRY OF THE CARBON COMPOUNDS EDITED BY PROF. R. ANSCHUTZ UNIVERSITY OF BONN AUTHORIZED TRANSLATION BY EDGAR F. SMITH PROFESSOR OF CHEMISTRY, UNIVERSITY OF PENNSYLVANIA Ubirfc Hmerican from tbe Ji0btb German Bfcftfon VOLUME 1 CHEMISTRY OF THE ALIPHATIC SERIES WITH ILL USTRA TIONS PHILADELPHIA P. BLAKISTON'S SON & CO IOI2 WALNUT STREET 1899 4 Copyright, 1899, by P. Blakiston's Son & Co. 7? WM. F. FELL & CO., ELECTROTYPERS AND PRINTERS, 1220-24 SANSOM STREET, PHILADELPHIA. f TTK PREFACE TO THE THIRD AMERICAN EDITION. In presenting this translation of the eighth German edition of v. Richter's " Organic Chemistry " the writer has little to add to what has previously been expressed in the prefaces to the preceding Ameri- can editions of this most successful book. The student of the present edition will, however, very quickly discover that the subject matter, so ably edited by Professor Anschtitz, is vastly different from that given in the earlier editions. Indeed, the book has sustained very radical changes in many particulars, and certainly to its decided ad- vantage. The marvelous advances in the various lines of synthetic organic chemistry have made many of the changes in the text abso- lutely necessary, and for practical reasons it has seemed best to issue this new edition in two volumes. Eminent authorities, such as Profs, v. Baeyer, E. Fischer, Waitz, Claisen, and others, have given the editor the benefit of their super- vision of chapters relating to special fields of investigation in which they are the recognized authorities. The translator here acknowledges his great indebtedness to his pub- lishers, P. Blakiston's Son & Co., for their constant aid in his work, as well as to Messrs. Wm. F. Fell & Co., for the care they have taken and the skill they have displayed in the composition of what will gen- erally be admitted to be a difficult piece of typography. PREFACE TO SECOND EDITION. The present American edition of v. Richter's " Organic Chemistry " will be found to differ very considerably, in its arrangement and size, from the first edition. The introduction contains new and valuable additions upon analysis, the determination of molecular weights, recent theories on chemical structure, electric conductivity, etc. The section devoted to the carbohydrates has been entirely rewritten, and presents the most recent views in regard to the constitution of this interesting group of compounds. The sections relating to the trimethylene, tetramethylene, and pentamethylene series, the fur- furane, pyrrol, and thiophene derivatives, have been greatly enlarged, while the subsequent chapters, devoted to the discussion of the aro- matic compounds, are quite exhaustive in their treatment of special and important groups. Such eminent authorities as Profs. Ostwald, von Baeyer, and Emil /Fischer have kindly supervised the author's pre- sentation of the material drawn from their special fields of investiga- tion. The characteristic features of the first edition have been retained, so that the work will continue to be available as a text-book for gen- eral class purposes, useful and reliable as a guide in the preparation of organic compounds, and well arranged and satisfactory as a refer- ence volume for the advanced student as well as for the practical chemist. The translator would here express his sincere thanks to Prof. v. Richter, whose hearty cooperation has made it possible for him to issue this translation so soon after the appearance of the sixth German edition. VI PREFACE TO THE FIRST AMERICAN EDITION. The favorable reception of the American translation of Prof, von Richter's "Inorganic Chemistry" has led to this translation of the " Chemistry of the Compounds of Carbon," by the same author. In it will be found an unusually large amount of material, necessitated by the rapid advances in this department of chemical science. The portions of the work which suffice for an outline of the science are presented in large type, while in the smaller print is given equally important matter for the advanced student. Frequent supplementary references are made to the various journals containing original arti- cles, in which details in methods and fuller descriptions of properties, etc., may be found. The volume thus arranged will answer not only as a text-book, and indeed as a reference volume, but also as a guide in carrying out work in the organic laboratory. To this end numerous methods are given for the preparation of the most important and the most characteristic derivatives of the different classes of bodies. VII CONTENTS. INTRODUCTION. Definition of Organic Chemistry, 17. Composition of Carbon Compounds, 18. Elementary Organic Analysis, 18. Determination of Carbon and of Hydrogen, 19. Determination of Nitrogen, 21. Determination of the Halogens, of Sulphur, of Phosphorus, 23. Deduction of Chemical Formulas, 25. (i) Determination of Molecular Weight by the Cnemical Method, 26. (2) Determination of the Molecular Weight from the Vapor Density, 27. (3) Determination of the Molecular Weights in Solu- tions : (a) from the Osmotic Pressure, 29 ; () from the Depression of the Vapor Pressure or the Rise in the Boiling Point, 30; (<:) from the Lowering of the Freezing Point, 32. Chemical Constitution of the Carbon Compounds, 34. Early Theories, 34. Recent Views, 36. The Principles of the Theory of the Chemical Structure of Carbon Derivatives, Atomic Linking or Structural Theory, 37. Saturated and Unsaturated Carbon Compounds, 38. Radicals, Residues, Groups, 39. Homo- logous and Isologous Series, 40. Isomerism : Polymerism, Metamerism, Chain or Nucleus Isomerism, Position or Place Isomerism, 41. Recent Views Pertaining to the Structure Theory, 43. Hypothesis of the Asymmetric Carbon Atom, 45. Isomerism of Optically Active Carbon Compounds, 46. Geometrical Isomerism, 49. Isomerism of the Ethylene Derivatives, 49. Hypotheses Relating to Multiple Unions of Carbon, 51. Stereochemistry of Nitrogen, 5 1 - Intramolecular Atomic Rearrangement, 5 2 - Pseudoforms, Pseudomerism (Tautomerism, Des- motropy, Merotropy), 54. Nomenclature of the Carbon Compounds, 57. Physical Properties of the Carbon Compounds, 58. I. Crystalline Form of the Carbon Compounds, 56. 2. Specific Gravity or Density, 5Q. 3. Melting Point, 6l. 4. Boiling Point (Distillation), 63. Distillation under Ordinary Pressure, 63. Distillation under Reduced Pressure, 63. Fractional Distil- lation, 64. Relations between Boiling Point and Constitution, 64. 5. Solu- bility, 64. 6. Optical Properties, 65. Color, 65. Refraction, 65. Optical Rotatory Power, 67. Decomposition of Optically Inactive Carbon Compounds into their Optically Active Components, 68. Conversion of Optically Active Substances into their Optically Inactive Modifications, 69. Magnetic Rotatory Power, 69. 7. Electric Conductivity, 70. Heat of Combustion of Carbon Com- pounds, 72. Action of Heat, Light, and Electricity upon Carbon Compounds, 73, 74, 76. Classification of the Carbon Compounds, 77. ix CONTENTS. FATTY BODIES, ALIPHATIC SUBSTANCES OR METHANE DERIVATIVES CHAIN-LIKE OR ACYCLIC CARBON COMPOUNDS, 77. I. HYDROCARBONS, 78. A. Saturated or Limit Hydrocarbons, Paraffins, 79. Methane, 80. Ethane, 82. Technical Preparation of the Limit Hydrocarbons, 87. B. Unsaturated Hydrocarbons. I. defines, 89. Ethylene, 90. 2. Acetylenes, 95. 3. Diolefines, 98. 4. Olefine Acetylenes, 99. 5. Diacetylenes, 99. II. HALOGEN DERIVATIVES OF THE HYDROCARBONS, 99. A. Halogen Paraffins, loi. Monohalogen Paraffins, loi. Dihalogen Paraffins, 101. Paraffin Polyhalides, 102. B. Halogen Derivatives of the Olefines and the Acetylenes, 104, 106. OXYGEN DERIVATIVES OF THE METHANE HYDROCAR- BONS, 106. III. THE MONOHYDRIC ALCOHOLS AND THEIR OXIDATION PRODUCTS, 109. i. Monohydric Alcohols, 109. A. LIMIT ALCOHOLS or PARAFFIN ALCOHOLS, 117. Methyl Alcohol, 117. Ethyl Alcohol, 1 1 8. Alcoholic Fermentation, 120. Propyl Alcohols, 125. Butyl Alcohols, 126. Amyl Alcohols, 127. Higher Homologous Limit Alcohols, 129. B. UNSATURATED ALCOHOLS, i. Olefine Alcohols. Allyl Alcohol, 130. 2. Acetylene Alcohols, 132. Propargy lie Alcohol, 132. 3. Diolefine Alcohols. Geraniol, 132. Alcohol Derivatives, 132. 1. SIMPLE AND MIXED ETHERS, 132. Methyl Ether, 134. Ethyl Ether, 134. 2. ESTERS OF THE MINERAL ACIDS, 136. A. I. Alkyl Esters of the Haloid Acids, Haloid Esters of the Saturated Alcohols, Alkylogens, 138. II. Haloid Acid Esters of the Unsaturated Alcohols, 142. B. Esters of Nitric Acid, 143. C. Esters of Nitrous Acid, 144. D. Esters of Sulphuric Acid, 144. E. Esters of Symmetrical Sul- phurous Acid, 146. F. Esters of Hypochlorous Acid and Per- chloric Acid, 147. G. Esters of Boric Acid, of Orthophosphoric Acid, of Symmetrical Phosphorous Acid, Arsenic Acid, Symmetrical Arsenious Acid and Silicic Acid, 147. 3. SULPHUR DERIVATIVES OF THE ALCOHOL RADICALS, 147. A. Mer- captans, Thio-alcohols and Alkyl-sulphydrates, 148. Ethyl Mer- captan, 149. B. Sulphides or Thio-ethers, 149. Allyl Sulphide, 150. C. Alkyl Disulphides, 150. D. Sulphine Compounds, 150. E. Sulphoxides and Sulphones, 151. F. Sulphonic Acids, 152. G. Alkyl Thiosulphuric Acids, 153. H. Alkyl Thiosulphonic Acids, 153. I. Alkyl Sulphinic Acids, 153. 4. SELENIUM AND TELLURIUM COMPOUNDS, 154. 5. NITROGEN DERIVATIVES OF THE ALCOHOL RADICALS, 154. A. Mononitro-paraffins and Olefines, 154. Appendix, 157. Ni- trolic Acids and Pseudonitrols, Dinitroparaffins, 157. CONTENTS. XI B. Alkylamines and Alkyl Ammonium Derivatives, 159. (a) Amines and Ammonium Bases with Saturated Alcohol Radicals, 166. Primary Amines, 166. Tetralkyl Ammonium Bases, 168. (6) Unsaiurated Amines and Ammonium Bases, 169. (c) Alkyl- amine Halides. 169. (d] Sulphur-containing Derivatives of the Alkylamines, 170. (d, 289. CONTENTS. Xiii IV. DIHYDRIC ALCOHOLS AND THEIR OXIDATION PRODUCTS, 289. 1. Dihydric Alcohols or Glycols. A. Paraffin Glycols, 291. Ethylene Glycol, 294. Pinacone, 296. B. Olefine Glycols, 297. GLYCOL DERIVATIVES, 297. i A. ALCOHOL ETHERS of the Glycols. B. Cyclic Ethers of the Glycols, Alkylen Oxides, 298. Ethylene Oxide, 298. 2. ESTERS OF THE GLYCOLS. A. Esters of Inorganic Acids, (a) Haloid Esters of the Glycols, 300. () Esters of Mineral Acids containing Oxygen, 303. B. Esters of Carbonic Acids, 303. 3. THIOCOMPOUNDS OF ETHYLENE GLYCOL. A. Mercaptans, 304. B. Sulphides, 304. C. Diethylene Tetrasulphide, 305. D. Sul- phine Derivatives, 305. E. Sulphones, 305. F. Sulphone-sul- phinic Acids and Disulphinic Acids, 305. Sul phonic Acids : Isethi- onic Acid. Taurine, 306. 4. NITROGEN DERIVATIVES OF THE GLYCOLS. A. Nitroso-compounds, 307. B. Nitro-compounds, 308. C. Amines and Ammonium Compounds, 308. (a) Oxalkyl Bases or Hydramines, 308 : Choline, 309. Neurine, 309. Betalne, 310. Morpholine, 310. (b] Halo- gen Alkylamines, 310. (c) Oxyethylamine Derivatives containing Sulphur, 311. (d) Alkylen Diamines, 311: Ethylene Diamine, ,312. (stance and the solvent; m and M are their molecular weights), for n and N, it will be easy to calculate the molecular weights. !'. M. Raoult (1887) developed these rules empirically. Soon thereafter van 't Hoff (Z. phys. Ch. 3, 115) deduced them theoretically from the osmotic pressure. They are only of value for non-volatile (as compared with the solvent) substances, or such as volatilize with difficulty. The same abnormalities observed with osmotic pressure and depression in the freezing point also appear here. The methods for the determination of vapor-pressure are yet too little known and primitive in their nature to be applied in the practical determination of molecular weights (B. 22, 1084 ; Z. phys. Ch. 4, 538). It is easier to determine the rise in the boiling points; this is also more reliable (Beckmann, Z. phys. Ch. 4, 539; 6, 437; 8, 223; 15, 656; B. 27, R. 727; 28, R. 432). Method of Beckmann. A small flask (Fig. 3) provided with three tubulures is used as the boiling vessel. A platinum wire s is fused into its bottom. This accel- erates the boiling. The flask is filled one-half (/) with glass beads. The wide side-tube D supports an accurate thermometer (Walferdin), which reaches to the contents of the vessel. Later its mercury reservoir is wholly immersed in the solvent. The condenser B is fixed in 6, so that the vapors can only reach it through the opening d. Its lower end should terminate about I cm. above the glass pearls, in order that rising vapor-bubbles do not retard the re- turning liquid. The flask, closed with stoppers, is carefully weighed to centigrams, and the solvent introduced until its level is at e. Its quantity is found by reweighing. The boiling vessel is now surrounded by an asbestos mantle, filled out above with cotton, but with an exposed bottom. The return-tube B is connected with a Soxhlet bulb- cooler or, if the metal is attacked, with an ordinary Liebig condenser. Note the boiling point of the solvent, and after the introduction of the substance through the tube C, determine the boiling point a second time. In this way we ascertain the rise in boiling point. Beckmann has so modified this appa- ratus as to make it applicable to solvents having high boiling points (Z. phys. Ch. 8, 223). S. Arrhenius has deduced a formula for molecular rise in boiling point, which is perfectly analogous to that deduced by van 't Hoff for the molecular depression of the freezing T 2 point. The molecular rise d is : d = 0.02. > in which T represents the absolute boiling point, and w the heat of evaporation of the solvent. Upon dissolving I gram-molecule of a substance, i. e. , if the mole- cular weight of the body is m, with m g of it in 100 grams of solvent, the boiling point will be raised about d, upon dissolving pg of the substance in loo gr. of solvent about d, d. -P ; from which FIG. 3. In this equation p = the weight (in grams) of the substance, dissolved in 100 grains of the solvent, (T 2 \ = O.O2. I W / dj = observed rise in boiling point. The molecular elevation of tjae boiling point in the case of ether is 21. 1, of chloroform 36.6, and of acetic acid 25.3. 32 ORGANIC CHEMISTRY. A. Naumann, B. n, 429, has devised a method for molecular weight determina- tion by the distillation of liquids not miscible with water. He conducts steam through them. 3. From the Depression of the Freezing Point. The mole- cular weights of dissolved substances are more accurately and readily deduced from the depression of the freezing points of their solutions. Blagden in 1788, and Riidorff in 1861, found that the depression of the freezing points of crystallizable solvents, or substances (as water, benzene and glacial acetic acid) is proportional to the quantity of substance dissolved by them. The later researches of Coppet (1871), and especially those of Raoult (1882), have established the fact that when molecular quantities of different substances are dissolved in the same amount of a solvent they show the same depression in their fre'ezing points (Law of Raoult). If / represents the depression pro- duced by/grams of substance in 100 grams of the solvent, the co-efficient of depression _ will be the depression for i gram of substance in 100 P grams of the solution.* The molecular depression is the product obtained by multiplying the depression co-efficient and the molecular weight of the dissolved substances. This is a constant for all sub- stances having the same solvent : M . l = C. P Raoult's experiments show the constant to have the following values : for benzene 49 ; for glacial acetic acid 39 ; for water 19. When the constant is known the molecular weight is calculated as follows : M = CP . t A comparison of the constants found for different solvents will disclose the fact that they bear the same ratio to each other as the molecular weights that conse- quently the quotient obtained from the molecular depressions and molecular weights is a constant value (about 0.62). It means, expressed differently, that the molecule of any one substance dissolved in 100 molecules of a liquid lowers the point of soli- dification very nearly 0.62. Guldberg (1870) and van 't Hoff (1886) have since made a theoretical deduction of these laws from the lowering of the vapor pressure, and from the osmotic pressure. The constant C is obtained, for the various solvents, from the formula 0.02 J_ w Here T indicates the temperature of solidification of the solvent calculated from the absolute zero-point forward ; w is its latent heat effusion. In this way van 't Hoff calculated the constants for benzene (53), acetic acid (38.8), and water 18.9 (see above). The laws just described possess a direct value for indifferent sub- stances, having but slight chemical activity. Salts, strong acids and * Arrhenius (Z. phys. Ch. 2, 493) expresses the content of solutions by the weight in grams of the substances contained in 100 c.c. of the solution. DETERMINATION OF THE MOLECULAR WFIC.UT. 33 bases (all electrolytes) constitute the exceptions. The depressions in freezing point are greater for these than their calculated values (they also have greater osmotic pressure, and greater lowering of the vapor pressure). The electrolytic dissociation theory of Arrhenius (Z. phys. Ch. i, 631, 577; 2, 491; B. 27, R. 542) would account for this by the assumption that the electrolytes have separated into their free ions. However even the indifferent bodies exhibit many abnormali- ties generally the very opposite of the ordinary. These seem to be due to the fact that the substances held in solution had not completely broken up into their individual molecules. The most accurate results are obtained by operating with very dilute solutions, and by employing glacial acetic acid as solvent. This dissociates solids most readily. Various forms of apparatus suitable for the above purpose, and methods of working have been proposed by Au- wers,* Hollemann (B. 21,860), Hent- schel,-f- Beckmann, J Eykmann, \ Klo- bukow, || and Baumann and Fromm (B. 24, 1431). Beckmann's Method. A hard glass tube, A, 2-3 cm. in width, side projection E (Fig. 4), is filled with 1 5-20 grams of the solvent (weighed out accurately in centigrams), and closed with a stopper, in which are placed an accurate thermometer (Walferdin), and a stout platinum wire serving as a stir- ring rod. The lower part of the tube is attached by means of a cork to a somewhat larger, wider tube. The latter serves as an air-jacket. The en- tire apparatus projects into a beaker glass filled with a freezing mixture. Cold water will answer for glacial acetic acid (congealing at 16), and ice-water for benzene (about 5). First determine the congealing point of the solvent by cooling it 1-2 below its freezing point, and then by agitation with the plati- num rod (after addition of platinum clippings), induce the formation of crystals. During this operation the thermometer rises, and when the mercury is stationary it indicates the freezing point of the solvent. Allow the mass to melt, and introduce an accurately weighed amount of substance through E. When this has dissolved the freezing point is re-detei mined as before (B. 28, R. 412). Eykmann's Method. (A. 273, 98). By this method it is possible to use smaller amounts of solution (6-8 grams) and substance. This is done by using phenol (m. p. about 38), as the solvent. Its molecular depression has been theo- retically deduced; it is about 76 (see above). Fig. 5 represents the form of appa- FIG. 4. FIG. 5. * B. 21, 711 ; | Z. phys. Ch. 2, 307 ; J Ibid. 2, 638 ; \ Ibid. 2, 964 ; || Ibid. 4, 10. 34 ORGANIC CHEMISTRY. ratus proposed by Eykmann. It is nothing more than a flask with two tubulures, in one of which a thermometer is fixed, and over the other is placed a ground-glass cap. Paterno's investigations show, contrary to earlier observations, that when benzene is employed as the solvent the carbon derivatives mostly yield normal results ; the exceptions being the alcohols, phenols, acids, oximes and pyrrol (B. 22, 1430 and Z. phys. Ch. 5, 94; B. 27, R. 845 ; 28, R. 974). Naphthalene may also be used for determinations of this kind, van 't Hoff gives its depression constant as equal to about 70 (B. 22, 2501 ; 23, R. I ; 24, 1431). Consult B. 28, 804 for a method of determining molecular weights from the decrease in solubility. For the determination of molecular weight from molecular solution-volume see B. 29, 1023. THE CHEMICAL CONSTITUTION OF THE CARBON COMPOUNDS. Early Theories. The opinion that the cause of chemical affinity resided in electrical forces, came to light in the commencement of this century, when the remarkable decompositions of chemical bodies, through the agency of the electric current, were discovered. It was assumed that the elementary atoms possessed different electrical polarities, and the elements were arranged in a series according to their electrical deportment. Chemical union depended on the obliteration of different electricities. The dtialistic idea of the constitution of compounds was a necessary consequence of this hypothesis. According to .it, every chemical compound was composed of two groups, electrically different, and these were further made up of two different groups or elements. Thus, salts were viewed as combinations of electro- positive bases (metallic oxides), with electro-negative acids (acid anhydrides), and these, in turn, were held to be binary compounds of oxygen with metals and non- metals. With this basis, there was constructed the electro-chemical, dualistic theory of Berzelius. This prevailed almost exclusively in Germany until about 1 860. The principles predominating in inorganic chemistry were also applied to organic substances. It was thought that in the latter complex groups (radicals) pre-existed, and played the same role that the elements did in mineral matter. Organic chemistry was defined as the chemistry of the compound radicals (Liebig, 1832), and led to the chemical-radical theory, which flourished in Germany simultaneously with the electro- chemical theory. According to this view, the object of organic chemistry was the investigation and isolation of radicals, in the sense of the dualistic idea, as the more intimate components of the organic compounds, and by this means they sought to explain the constitution of the latter. (Liebig and Wohler, Ueber das Radical der Benzoesaure, A. 3, 249; Bunsen, Ueber die Kakodylverbindungen, A. 31, 175; 37, I; 42, 14; 46, I.) In the meantime, about 1830, France contributed facts not in harmony with the electro-chemical, dualistic theory. It had been found that the hydrogen in organic compounds, could be replaced (substituted) by chlorine and bromine, without any apparent change in the character of the compounds. To the electro-negative halogens was ascribed a chemical function similar to electro-positive hydrogen. This showed the electro-chemical hypothesis to be erroneous. The dualistic idea was superseded by a unitary theory. Laying aside all the primitive speculations on the nature of chemical affinity, the chemical compounds began to be looked upon as constituted in accordance with definite mechanical ground-forms types in which the individual elements could be replaced by others (early type theory of Dumas, nucleus theory of Laurent). Dumas, however, distinguished between chemical types and mechanical types. He considered substances to have the same chemical type, to be of the same species, when they possessed like fundamental properties, e. g., acetic and chlor- acetic acids. Like* Regnault he said they were of the same mechanical type, belonged to the same natural family, when they were related in structure but THK fHKMU'AI. CONSTITUTION OF THE CARBON ( OMI'OrXDS. 35 manifested a different chemical character: alcohol and acetic acid. At the same time the dualistic view on the pre-existence of radicals was refuted. The correct establishment of the ideas, equivalent, atom and molecule (Laurent and Gerhardt), was an important consequence of the typical unitary idea of chemical compounds. By means of it a correct foundation was laid for further generalization. The molecule having been determined a chemical unit, the study of the grouping of atoms in the molecule became possible, and chemical constitution could again be more closely examined. The investigation of the reactions of double decomposition, whereby single atomic groups (radicals or residues) were preserved and could be exchanged (Gerhardt) ; the important discoveries of the amines or substituted ammonias by \Yiirtz (1849), and Hofmann (1849) > ^ e epoch-making researches of Williamson and Chancel (1850), upon the composition of ethers, and the discovery of acid-forming oxides by Gerhardt (1851) led to a "type" explanation of the individual classes of compounds. Williamson referred the alcohols and ethers to the water type. A. W. Hofmann deduced the substituted ammonias from ammonia. The " type" idea found its culmination in the type theory of Gerhardt (1853), which was nothing more than an amalgamation of the early type or substitution theory of Dumas and Laurent with the radical theory of Berzelius and Liebig. The molecule was its basis and to it there was attached a more extended grouping of the atoms in the molecule. The conception of radicals became different. They were no longer regarded as atomic groups that could be isolated and compared with elements, but as molecular residues which remained unaltered in certain reactions. Comparing the carbon compounds with the simplest inorganic derivatives, Ger- hardt referred 'them to the following principal fundamental forms or types : H \ C1 \ H \0 H l H/ Hf H/ u HlN rdrogen. Hydrogen Water. H J Hydrogen. Hynroger Chloride. Ammonia. From these they could be obtained by substituting the compound radicals for hydrogen atoms. All compounds that could be viewed as consisting of two directly combined groups were referred to the hydrogen and hydrogen chloride types, e. g. : CN } C fc H 5} C,H S } Ethyl Ethyl Cyanogen Ethyl Acetyl Hydride. Chloride. Hydride. Cyanide. Chloride. It is customary to refer all those bodies derivable from water by the replacement of hydrogen, to the water type : Alcohol. Acetic Acid. Ethyl Ether. Acetic Anhydride. Associated types were included with the principal types. Thus, with the funda- mental type 5 1 were arranged as subordinates, the types jj j ^ j ; with the water type [ | O that of j j S, etc. The compounds containing three groups united by nitrogen are considered ammo- nia derivatives : cn 3 ) CILJ as drawn by Gerhardt did not exist for Kekule. The latter in 18^8 I H j J said, " it is necessary in explaining the properties of chemical compounds to go back to the elements which compose these compounds." He continues: "I do not regard it as the chief aim of our time to detect atomic groups which, owing to certain properties, may be considered radicals and thus to include the compounds under certain types, which in this way have scarcely any other significance than that of type or example formula. I am rather of the opinion that the generalization should be extended to the constitution of the radicals themselves, to the determina- tion of the relation of the elements among themselves, and thus to deduce from the nature of the elements both the nature of the radicals and that of their compounds." (A. 106, 136.) The recognition of the quadrivalence of the carbon atoms and the power they possessed of combining with each other, accounted for the existence and the com- bining value of radicals; also, for their constitution (Kekule, /. c., and Couper, A. ch. phys. [3] 53, 469). The type theory, consequently, is not as sometimes declared, laid aside as erroneous; it has only found generalization and amplification in a broader principle : the extension of the valence theory of Kekule and Couper to the derivatives of carbon. While formerly it was customary to consider in addition to empiric formulas, repre- senting merely an atomic composition of the molecule, rational formulas (Berzelius), which in reality were nothing more than rearrangement formulas adopted to explain to a certain degree the chemical behavior of derivatives of carbon, Kekule spoke of the manner of union of the atoms in the molecule, by knowledge of which the con- stitution of the carbon compounds is determined (constitution formulas). Lothar Meyer next introduced the phrase " linking of the carbon atoms" The expression structure (structural formulas) originated with Butlerow. An application of the valence theory, which has been remarkably fruitful, is the Kekule benzene theory. Here for the first time there was assumed present in a carbon compound a closed carbon-chain, a ring consisting of six carbon atoms. The rather singular stability of the ammatic bodies is due to the presence of this " benzene ring." Korner applied these views to pyridine and deduced the pyridine ring. In rapid succession numerous other rings have followed and have arranged themselves side by side with the old rings in more recent years. Theory of Chemical Structure of Carbon Compounds. Theory of Atomic Linking or the Structural Theory. Constitutional or structural formulas are based upon the following principles, which have been deduced from experiment and repeatedly confirmed by the same. i. The carbon atom is quadrivalent The position of carbon in the periodic system gives expression to this fact. One carbon atom can combine at the most with four dissimilar or similar univalent atoms or atomic groups: CH 4 CF 4 CC1 4 Mi-thane. Carbon Tetrafluoride. Carbon Tetrachluiide. 38 ORGANIC CHEMISTRY. CH 3 C1 CH 3 NH 2 CH 2 C1 2 CHC1 3 Methyl Chloride. Methylamine. Dichlormethane. Chloroform. In a few compounds, e. g., carbon monoxide CO and the isonitriles or carbylamines R / N C (A. 270, 267) and fulminic acid HO N = C (A. 280, 303) carbon figures as a bivalent element. 2. The four affinity units of carbon are, as generally represented, equal and similar, i. e., no differences can be discovered in them when they form compounds. If one of the four hydrogen atoms in the simplest hydrocarbon, CH 4 , be replaced by a univalent atom or univalent atomic group, each monosubstitution product will appear in but one modification. The four hydrogen atoms are similarly combined, consequently it is imma- terial which of them is replaced. CH 3 C1 CH 3 OH CH 3 NH 2 Chlormethane. Methyl Alcohol. Methylamine. are known in but one modification each (p. 46). 3. The carbon atoms can unite with each other. When two carbon atoms combine the. union can occur in three ways: (a) The two carbon atoms unite with a single valence each, leaving the atomic group, E= C C == , with six free valences. (b} The two carbon atoms unite with two valences each, then the atomic group, C = C , with four free valences, remains. (c} Two carbon atoms are united by three valences. The residual group C = C has but two uncombined valences. In the first case the union of the two carbon atoms is single, in the second case double, and in the third case triple. Carbon atoms can combine to a greater degree with themselves than the atoms of any other elements. This gives rise to carbon nuclei, carbon skeletons, which form either open or closed carbon chains or rings. The uncom- bined valences of the carbon nuclei can saturate or take up the atoms of other elements or other atomic groups. This would explain the existence of the almost numberless carbon compounds. The 'mutual union is indicated by formulas or, according to the recommendation of Couper, by lines. These formulas represent the structure of the compounds ; they are structural formulas : H II H H I II I H C H H C Cl H C O II H C N A i i II II Saturated and Unsaturated Compounds. Saturated carbon compounds are those in which the carbon atoms are united by a single bond to each other. They cannot be united by more valences unless the carbon chain is broken up. Unsaturated compounds are those in which a double or triple union between carbon atoms exists. As a single union is sufficient to link carbon atoms together, a pair of car- THE CHEMICAL CONSTITUTION OF THE CARBON COMPOUNDS. 39 bon atoms with double union can take up two additional valence units. This would dissolve the double union, giving rise to single linkage without destruction of the chain, e.g. H H C II I + 2H = H C H H C H Ethylene. H_C H H Ethane. Two carbon atoms, trebly linked, can take up four valences. The dissolution of the triple union may proceed step by step. The triple linkage may first be changed to a double linkage and then to a simple union : H C II 2H H_C H 2ll II C H III > II > I C-H H-C H II C II H The unsaturated compounds, by the breaking-down of their double and triple unions and the addition of two or four univalent atoms, pass into saturated compounds. This same deportment is observed with many other compounds containing carbon and oxygen, doubly combined, = C = O (aldehydes and ketones) or double and triple union of carbon and nitrogen, = C = N CEEN (acid nitriles, imides, ox- imes). They are in the same sense unsaturated; by the breaking down of their double or triple union they change to saturated compounds in which the polyvalent atoms are linked by a single bond to each other : H II C NIL, H C H-(-4H = A "-{-" H Acetaldehyde. Ethyl Alcohol. Acetonitrile. Ethylamine. Radicals, Residues, Groups. The assumption of radicals, able to exist alone and play a special role in molecules, has been abandoned. The structural formulas are unitary formulas they give no especially favorable position to one atom over another in the molecule. Radicals are atomic groups, chiefly those containing carbon, which in many reactions are unaltered and pass from one compound into another. In this category must also be included the uni-, bi-, tri-, and poly- valent atomic complexes, which remain when atoms or atomic groups are removed from saturated bodies. By the gradual removal 40 ORGANIC CHEMISTRY. of hydrogen methane yields the following radicals, having different valences : CH 4 CH 3 =CH 2 =CH Methane Methyl Methylene Methenyl or Methine saturated. univalent radical. bivalent" radical. trivalent radical. If such radicals are isolated from proper compounds, e. g., the halogen derivatives, then two of them unite to form a molecule : CH 3 I CII, + 2Na = | CH 3 I CH 3 CH 2 T 2 CH 2 + 4Cu = || CH I, CH., CHC1 3 CH CHC1 3 6Na = m -f 6NaCl Or, an atomic rearrangement may occur with the production of a molecule of the same number of carbon atoms : CHC1 2 CH 2 CH= | ' + 2Na = || '+ 2NaCl (and not) | CH 3 CH 2 CH 3 The expressions residue and group are similar to radical. They are chiefly applied to inorganic radicals, e.g., OH water residue or hydroxyl group, SH hydrogen sulphide residue or sulphydrate group, NH 2 ammonia residue or amido group, ^=NH imido group, NO 2 nitro group, NO nitroso group. Homologous and Isologotis Series. Schiel, in 1842 (A. 43, 107 ; no, 141), directed attention to the phenomenon of homology, giving as evidence the alcohol radicals. Shortly after Dumas observed it in the fatty acids. Gerhardt introduced the terms homologous and isologous series, and showed the role these series assumed in the classification of the carbon derivatives. It was the theory of atomic linking that first disclosed the cause of homology. The different manner, in the linking of the carbon atoms, shows itself most plainly in their hydrogen compounds in the so-called hydrocarbons. By removing one atom of hydrogen from the simplest hydrocarbon, methane, CH 4 , the remaining univalent group, CH 3 , can combine with another, yielding CH 3 CH 3 , or C 2 H 6 , ethane or di- methyl. Here, again, an hydrogen atom may be replaced by the group CH 3 , resulting in the compound CH 3 CH 2 CH 3 , propane. The structure of these derivatives may be more clearly represented graphically : THE CHEMICAL CONSTITUTION OF THE CARBON COMI'< H' M>s. 41 II H H H H H H C H H C C H H C C C H, etc. I II III H H II H II 11 CH 4 C 2 H 6 C 3 H 8 By continuing this chain-like union of the carbon atoms, there arises an entire series of hydrocarbons : CH 3 CH 2 CH 2 CH 3 CH 3 CH, CH 2 CH 2 CH 3 , etc. C 4 H 10 C 5 H 12 The compounds constituting such a series are said to be homologous. The composition of such an homologous series can be expressed by a general empiric or rational formula. The series formula for the marsh gas or methane hydrocarbons is C n H 2n + 2 . Each member differs from the one immediately preceding and the one following, by CH 2 . The phenomenon of homology is therefore due to the linking power of the quadrivalent carbon atoms. In addition to the hydrocarbons forming such a series, many others exist, e. g.; the monohydric alcohols, the aldehydes and monobasic acids : CH 4 O methyl alcohol CH 2 O formaldehyde CH 2 O 2 formic acid C 2 H 6 O ethyl alcohol C 2 H 4 O acetaldehyde C 2 H 4 O 2 acetic acid C 3 H 8 O propyl alcohol C 3 H 6 O propionaldehyde C 3 H 6 O 2 propionic acid C 4 H 10 O butyl alcohol C 4 H 8 O butyraldehyde C 4 H 8 O 2 butyric acid. Carbon compounds, alike chemically, but 'differing from each other in composition by a difference other than nCH 2 , e.g., the saturated and unsaturated hydrocarbons, form isologous series, according to Gerhardt : C 2 H 6 - C 2 H 4 - C 2 H 2 C 3 H 8 C 3 H 6 C 3 H 4 Isomerism: Polymerism ; Metamerism; Chain or Nucleus Isomerism ; Position or Place Isomerism. The view once prevailed that bodies of different properties must necessarily possess a different composition. The first hydrocarbons, showing that this opin- ion was erroneous, were discovered in 1820. Liebig, in 1823, demonstrated that silver cyanate and fulminate were identical. In 1825 Faraday found in a compressed gas a liquid hydrocarbon having the same com- position as gaseous ethylene. In 1828 Wohler changed ammonium cyanate to urea, and in 1830 Berzelius established the similarity of tartaric acid and racemic acid. Berzelius, in 1830, designated as isomerides (iffu^pTJ^] bodies of sim- ilar composition, but different in properties. A year later he distin- guished two kinds of isomerism, viz., isomerism of bodies of different molecular masspolymerism, and bodies of like molecular mass meta- merism. Numerous isomeric carbon derivatives were discovered in rapid suc- cession, hence an answer as to the question what causes isomeric phe- 4 ORGANIC CHEMISTRY. nomena acquired importance for the development of organic chemistry. The deeper insight into the structure of carbon compounds, which was gradually attained, gave rise in consequence to a further division of metameric phenomena. The expression metamerism was employed to designate that kind of isomerism which is due to the homology of radicals held in combina- tion by atoms of higher valence. If the homologous radicals are joined by polyvalent elements, then those compounds are metameric, in which the sum of the elements, contained in the radicals, is the same (H may be viewed as the simplest radical) : is metameric with Ethyl Alcohol. O is metameric with Propyl Alcohol. H L N is metameric with Ethylamine. HJ CHj} Methyl Ether. C 2 H 5 |c) CH 3 J Ethyl Methyl Ether. CHg CHg H Dimethylamine. H Propylamine. N is metameric with CH* I N and CH! I N H J CH 3 j Ethyl Methyl- amine. CH a CH a Trimethyl- amine. The constitution of the radicals in this division was disregarded, the type formulas were sufficiently explanatory. We have recognized the power of the quadrivalent carbon atoms to unite in a chain-like manner as the cause of homology, and to this cause may be attributed other phenomena of isomerism, which are not properly included under metamerism. In deducing the formulas of the five simplest hydrocarbons of the homologous series C n H 2n + 2 j the ethane formula CH 3 . CH 3 was de- veloped from that of methane CH 4 , and the propane formula CH 3 .CH 2 .CH 3 from the ethane formula C 2 H 6 . In the case of propane intermediate and terminal carbon atoms are distinguished. The former are attached on either side to two other carbon atoms, still possess- ing two valence units which are saturated by two hydrogen atoms. The terminal carbon atoms are linked to three hydrogen atoms. With the next member of the series we observe a difference. Above, the fact that an hydrogen of the terminal methyl group of propane was replaced by methyl waiTtrie only condition considered. This led to the formula CH 3 . CH 2 . CH 2 . CH 3 . However, the CH 3 -group might replace an hydrogen atom of the intermediate CH 2 -group, and CH 3 .CH.CH 3 . then the result would be the formula | . In this hydrocar- in. THE CHEMICAL CONSTITUTION Ol TH K ( ARBON COMPOUNDS. 43 bon there is a branched carbon chain. The hydrocarbon with a con- CHj.CJl .(II, tinuous chain is termed butane; its isomeride is isobutane CH 3 Theoretically, by a similar deduction, the two butanes yield three isomeric pentanes: CH 3 CH S . CH, . CH 2 . CH 8 . CH S CH 3 . CH . CH 2 . CH 3 . H 3 C C CH 3 Normal Pentane. CH 3 CH 3 Isopentane. Pseudopentane Tetramethyl Methane. These hydrocarbons are really known. The number of possible isomerides increases rapidly with the increase in carbon atoms (B. 27, R. 725). The cause of isomerism in the homologous paraffins, as in so many other cases, is the different constitution of the carbon chain. The isomerism caused by a difference in linking, by the different structure of the carbon nucleus or the carbon chain, is termed nucleus or chain isomerism. The investigation of the substitution products of the paraffin hydro- carbons brings to light another kind of isomerism. The principle of similarity of the four valences of a carbon atom renders logical and possible but one monochlor substitution product of methane and ethane. The same consideration which heretofore recognized the possibility of two methyl substitution products of propane, the two butanes possible by theory, leads to the possibility of two monochlor-propanes, depend- ent upon whether the chlorine atom has replaced the hydrogen of a terminal or intermediate carbon atom : CH 3 . CH 2 . CH 2 C1 CH 3 . CHC1 . CH 3 Normal Propyl Chloride. Isopropyl Chloride. If t\vo hydrogen atoms of one of, the carbon atoms of propane be replaced by an oxygen atom, the following case of isomerism arises : CH 3 . CH 2 . CHO CH 3 . CO . CH 3 Propyl Aldehyde. Acetone. In the case of the two known chlorpropanes, and also in the case of propyl aldehyde and acetone, the cause of the isomerism is not due to difference in constitution of the carbon chain, but to the different position of the chlorine atoms with reference to the oxygen atoms of the same carbon chain. Isomerism, induced by the different arrange- ment or position of the substituting elements in the same carbon chain, is designated isomerism Q{ place or position. The intimate relationship of the two varieties of isomerism is appa- rent from the derivation of the ideas of nucleus or chain isomerism and place or position isomerism. Recent Views Pertaining to the Structural Theory. The theory of atomic linking not only revealed an insight into the causes of 44 ORGANIC CHEMISTRY. innumerable isomeric phenomena, but predicted unknown instances and determined their number in a very definite manner. In many cases isomeric modifications, possible by theory, were discovered at a later period. For certain isomerides, however, at first few in number, the structural formulas deduced from their synthetic and analytical reac- tions were insufficient, inasmuch as different compounds were known, to which the same structural formula could be given. The greatest similarity in reactions indicative of the structure was combined with a pre-eminently absolute difference in physical properties of the com- pounds belonging in this class. The tendency at first was to designate such bodies physical isomerides, meaning thereby an aggregation of varying complexes of chemically similar molecules. The following groups of such isomerides have been well investigated : HOHC . CO 2 H 1. The four symmetrical dioxysuccinic acids : , the or- HOHC . C0 2 H dinary or dextrotartaric acid, and racemic acid which were proved to be isomeric in 1830 by Berzelius. To these were added, through Pasteur's classic researches, laevo-tartaric and the inactive or meso- tartaric acids. CH . CO 2 H 2. The two symmetrical ethylene dicarboxylic acids : || , fu- maric and maleic acids. CH . CO 2 H 3. The three a-oxypropionic acids : CH 3 . CH . OH . CO 2 H inactive lactic acid of fermentation and sarcolactic acid. To these, Isevolactic acid has been recently added. Substances are included among these compounds, which liquified, either fused or in solution, turn the plane of polarization either to the right or left. The direction of deviation is indicated by prefixing " dextro " or " laevo " to the name of the bodies thus acting. Such carbon compounds are "optically active" in contradistinction to the other almost numberless derivatives which exert no influence on polarized light and are "optically inactive " or " inactive." A direct synthesis of optically active carbon compounds has not yet been achieved, although optically inactive bodies have been syn- thesized. Pasteur has discovered methods by means of which the latter can be resolved into their components, which rotate the plane to an equal degree but in opposite direction. Upon splitting sodium- ammonium racemate into sodium-ammonium laevo- and dextro-tartrates Pasteur observed that the crystals of these salts manifested hemi- hedrism; that they behaved as an object and its image toward each other ; and that like layers of equally concentrated solutions of these salts, at like temperature, deviated the plane of polarized light to an equal degree in opposite directions. In 1860 Pasteur expressed himself as follows upon the cause of these phenomena upon molecular asymmetry : ' ' Are the atoms of the dextro-acid grouped in the form of a dextro-gyratory spiral, or are they arranged at the angles of an irregular tetrahedron, or are they distributed according to some other asymmetric arrangement ? We know not. Undoubtedly, however, we have to do with an asymmetric arrangement, the THE CHEMICAL CONSTITUTION OF THE CARBON COMPOUNDS. - 45 images of which cannot mutually cover each other. It is not less certain that the atoms of the livo-acid are arranged in opposite order." In 1873 J. \Vislicenus added this comment to the evidence of similar structure in the optically inactive lactic acid of fermentation and the optically active sarcolactic acid : " Facts compel us to explain the difference of isomeric molecules of like structural formula by a difference in arrangement of the atoms in space." How the spacial configuration of the molecules of carbon compounds was to be represented was answered almost simultaneously and independently of each other by van't Hoff and Le Bel (1874) ( 1>. 26, R. 36). To do this they introduced the hypothesis of the asymmetric carbon atom. This hypothesis is the basis of the chemistry of space or stereo- chemistry of the carbon atom. The hypothesis of an asymmetric carbon atom* is chiefly designed to explain optical activity and the isomerism of optically active carbon compounds. While the theory of atomic linking abstains from any representation of the spacial arrangement of the atoms combined with each other to form a molecule, the experiences gathered from the investigation of simple carbon compounds demonstrate that definite spacial position- relations do not harmonize with actual facts. Assuming that the four valences of. a carbon atom act in a plane and in perpendicular direc- tions upon each other, the following possible isomerides for methane are evident : No isomerides of the types CHsR 1 and Two " " " CH/R 1 ),, CH 2 R'R 2 , Three " " " " CHR'R'R 3 . Methylene iodide, for example, should appear in two isomeric modifications : H H I C I and H C I 4 ' '. - ; '1 However, two isomerides of no single disubstitution product of methane have been found ; consequently, it is very improbable that the four affinities of a carbon atom are disposed in the manner indi- cated above. The carbon atom- models of Kekule" represent the carbon atom as a black sphere and the quad ri valence of it by four needles of equal length and firmly attached to the sphere (Baeyer terms them axes). These needles are not perpendicular to each other, nor do * Pasteur: Recherches sur la dissymetrie moleculaires des produits organiques naturels. Lecons de chimie professees en 1860. Paris, 1861. Vgl. Ostwald's Klassiker der exacten Wissenschaften, Nr. 28: Ueber die Asymmetrie bei natiirlich vorkommenden organischen Verbindungen, von Pasteur. Uebersetzt und herausgegeben von M. und A. Ladenburg. J. H. van 't Hoff: Dix annees dans Phistoire d'une theorie, 1887. K. Auwers: Die Entwickelung der Stereochemie, Heidelberg, 1890. A. Hantzsch : Grundriss der Stereochemie, Breslau, 1893. C. A. Bischoff : Handbuch der Stereochemie, 1893. 40 ORGANIC CHEMISTRY. they lie in the same plane, but are so arranged that planes placed about their terminals produce a regular tetrahedron, van 't Hoff's generali- zations are based upon this model : their fundamentals will be more fully developed in the following pages. On the assumption that the affinities of a carbon atom are arranged like the summits of a regular tetrahedron, in the center of which there is the carbon atom, there would be no imaginable isomerides coincid- ing with CH 2 (R% CH^R 2 , CHR'CR 1 ),, but a case CHR'R'R 3 or the more general CR ! R 2 R 8 R 4 an isomeric phenomenon of peculiar nature might be predicted. A carbon atom of this description one that is connected with four different univalent atoms or atomic groups van 't Hoff has designated an asymmetric carbon atom, proposing to represent it by an italic C. It is sometimes indicated by a small star. If a compound contains an asymmetric carbon atom we can con- ceive of its existence in two isomeric modifications, the one being an image of the other : These spacial arrangements are more fully understood by the aid of the models suggested by Kekule, van 't Hoff, and others than by their projection upon the flat surface of paper, van't Hoff introduced tetrahedron models in which the solid angles were colored ; this was to represent and indicate different radicals. They lack this advantage, possessed by the Kekule model, that the carbon atom has entirely dis- appeared from the model. It must be imagined as being in the center of the tetra- hedron, and in projections of these models (see above) the radicals are united to each other by lines, the latter, however, not in any sense representing a chemical union. In the left tetrahedron the successive series R ! R 2 R 3 proceeds in a direction directly opposite to that of the hand of a watch, while in the right tetrahedron the course coincides with that of the hand. The two figures cannot, by rotation, be by any means brought into the same position, that is, in a position to cover each other completely, any more than the left hand can be made to cover the right, or a picture its image or reflection. The Isomerism of Optically Active Carbon Compounds. The cause of optical activity, in the opinion of van 't Hoff. and of Le Bel, is the presence of one or several asymmetric carbon atoms in the molecule of every optically active body. It is obvious that two molecules which only differ in that the series of atoms or atomic groups attached to an asymmetric carbon atom differ successively in order of arrange- ment, which therefore are identical in chemical structure, must be so similar in chemical properties as to give rise to confusion. However, THE CHK.MICAL CONSTITUTION OF THK CARBON COMl'nCND;- 17 those physical properties, upon which the opposite successive series of atoms or atomic groups in union with asymmetric carbon exerts an influence, e. g., the power of deviating the plane of polarized light, must be equal in value, but as regards the prefix they are opposite. The union of two molecules identical in structure, having equal but opposite rotatory power, gives rise to a molecule of an optically inac- tive polymeric compound. Compounds Containing an Asymmetric Carbon Atom. a Oxypro- pionic acid, CH 3 *CHOH . CO 2 H, has been brought forward as an example of a compound, containing one asymmetric carbon atom. It can appear in two optically active, structurally identical, but physi- cally isomeric and one optically inactive, structurally identical poly- meric modifications ; OH Dextro-lactic Acid. (Sarcolactic Acid.) OH i-H COJf CO,H OH Laevo-lactic Acid. CO,H CH 3 f , , x , T ..., /\IT A -J 1 Lactic Acid of Fermentat { ( + ) cl-LacticAcul (-) 1-Lact.c Ac.d |= or Inactive Lactic Acid . The following compounds also contain one asymmetric carbon atom : Leucine, ... C 4 H 9 *CHNH 2 . CO 2 H Malic Acid, . ..... C0 2 H. CH 2 . *CH OH. CO 2 H Asparagine, ............ CO NH 2 . -CH 2 . *CHNH 2 . CO 2 H Mandelic Acid, .......... C 6 H 5 . *CH.OH. CO 2 H l^S <) Conine Each of the preceding bodies is known in two optically active and one optically inactive modifications. Compounds Containing Two Asymmetric Carbon Atoms. The rela- tions are more complicated when two carbon atoms are present. The simplest case would then be that in which similar or like groups are in union with the two asymmetric carbon atoms. The one-hall of 4 8 ORGANIC CHEMISTRY. the molecule would be constructed chemically just like the other half. The four isomeric dioxysuccinic acids belong in this group. This group of so-called tartaric acids has become of the greatest importance in the development of the chemistry of optically active carbon derivatives. They were the first to be most carefully investigated chemically, optically, and crystallographically, and were used by Pasteur in the development of methods for the splitting-up of the optically inactive compounds into their optically active components (p. 65). Their importance was increased in addition by the fact that they were brought into an intimate genetic relation with fumaricand maleic acids two isomeric bodies which will be considered in the next section (P- 5)- Should a carbon compound contain two asymmetric carbon atoms united to similar groups then to the three isomeric modifications which a compound containing one asymmetric carbon atom is capable of forming comes a fourth possibility. If the groups linked to one asymmetric carbon atom, viewed from the line of union of the two asymmetric carbon atoms, show an opposite successive arrangement to that of the other asymmetric carbon atom, an inactive compound results, due to an intramolecular compensation : the action due to the one asymmetric atom upon polarized light will be canceled by an equally great, but opposite action caused by the other asymmetric carbon atom. The hypothesis of the asymmetric carbon atom gave the first and, indeed, the only satisfactory explanation for the occurrence of four isomeric symmetrical dioxysuccinic acids. The following formulas represent these four acids : >OH - 'HO C OH v^v-'2 J - JL \-^V_/Q JLA vAJoii (i) Dextrotartaric Acid. (2) Laevotartaric Acid. (3) Inactive or Mesotartaric Acid. Dextrotartaric Acid + Laevotartaric Acid = (4) Racemic Acid. THE CHEMICAL CONSTITUTION OF THE CARBON CUMPOUMiS. ^9 The possibilities of isomerism with carbon compounds containing more than two asymmetric carbon atoms a condition observable with the polyhydric alcohols, their corresponding aldehyde alcohols, and ketone alcohols (the simplest sugar varieties), as well as with their oxidation products, will be more elaborately discussed under these several groups of compounds. Geometrical Isomerism, Stereoisomerism in the Ethylene Derivatives (Alloisomerism}. Two carbon atoms singly linked to each other whose valences, not required for mutual union, hold other atoms or atomic groups, should be considered as able to rotate independently of each other about their axis of union. J. Wislicenus assumes, however, that the atoms or atomic groups combined with these two carbon atoms exercise alternately a " directing influence" upon each other until finally the entire system has passed into the " favorable configuration" or the " preferred position." It follows from this assumption that, in ethane derivatives in which asymmetric carbon atoms are not present, structurally identical isomerides cannot occur. When the van 't Hoff tetrahedron models are employed to represent two systems united to each other by carbon atoms singly linked then the two systems rotating independently of each other about a common axis move each in the solid angle of a tetrahedron (com- pare the projection-formula of the tartaric acids shown above). A different state prevails where the carbon atoms are doubly linked. The double union, according to van 't Hoff, prevents a free and independent rotation of the two systems and space-isomerides are possible. The tetrahedron models represent this double union in such a manner that two tetrahedra have two summits in common and arrange themselves about a common edge. The differences in chemi- cal deportment of this class of isomerides are frequent and important. They are to be attributed to the greater or less spacial removal of the atomic groups, which determine the chemical character. Compounds having the common formulas abC Cab or abC = Cac, may exist in two isomeric modifications. In one instance groups of like name are directed toward the same side according to J. Wislicenus the "plane symmetric configuration" or they are directed toward opposite sides then they have according to the same author the central or axially symmetric configuration. Baeyer suggests for this form of asymmetry the term "relative asymmetry" in contradistinction to the kind of asymmetry which substances with asymmetric carbon atoms show ; the latter he prefers to call " absolute asymmetry." The structurally symmetric ethylene dicarboxylic acid is the most striking example of this class of isomerism. It exists in two isomeric modifications. They are fumaric and maleic acids. Both have been very carefully investigated. Maleic acid readily passes into an anhydride, hence the plane symmetric configuration is ascribed to it. Fumaric acid does not form an anhydride; to it is given the axial symmetric configuration. In this the two carboxyl groups are as 5 ORGANIC CHEMISTRY. widely removed from each other as possible. In projection formulas and in structural formulas, to which there is given a spacial aspect, the configuration of these two acids would be represented in the following way : Malei'c Acid. Plane Symmetric Configuration. HO.C Fumaric Acid. Central or Axially Symmetric Configuration. The isomerism of mesaconic and citraconic acids, (CH 3 ) (CO 2 H) C = CH (CO 2 H), is of the same class ; the first acid corresponds to fumaric acid and the second to malei'c acid. Further examples of the class are : Crotonic and Isocrotonic Acids, Angelic and Tiglic Acids, Oleic and Elaidic Acids, . Erucic and Brassidic Acids, The two a-Chlorcrotonic Ac ds, " " /3-Chlorcrotonic Acids, '* " Tolane Bichlorides, . " " " Dibromides, . " " o-Dinitrostilbenes, . . Cinnamic and Allocinnamic Acids CH 3 CH : CHCO 2 H. CH 3 . CH : C (CH 8 ) CO 2 H. C 15 H 31 CH : CHCO 2 H. C 8 H 17 CH : CH. C n H 22 . CO 2 H. CH 3 . CH : CC1. C0 2 H; CH 3 . CC1:CH. C0 2 H. C 6 H 5 CC1:CC1C 6 H 5 . C 6 H,CBr:CBr C 6 H-. N0 2 [2] C 6 H 4 [i] CH , C 6 H 5 . CH : CH CO 2 H. CH [i] C 6 H 4 ] 2 ] N0 2 . The two a-Bromcinnamic Acids, C 6 H 5 . CH " . " /3-Bromcinnamic " C 6 H 5 . CBr : CH CO 2 H. " " Coumaric " HO [2] C 6 H 4 [i] CH : CH. CO 2 H, etc. Isomeric phenomena of this kind Michael designates allo-isomerism : he connects with it, however, no assumption as to its cause. When, upon the application of heat, a body passes into a more stable modifi- cation Michael prefixes " allo " to the name of the more stable form ; thus, fumaric acid is allomalei'c acid (B. 19, 1384). Fumaric and malei'c acids are placed at the head of this class of isomeric phenomena not only because they have been most thoroughly investigated, but chiefly because the two optically inactive dioxytar- taric acids bear to them an intimate genetic relation (p. 48). Kekule and Anschiitz showed that by potassium permanganate fumaric acid was converted into racemic acid, and malei'c acid into mesotartaric acid. This conversion harmonizes beautifully with the van 't Hoff-Le Bel con- ception of these acids ; indeed, it might have been predicted. These rela- tions will be more fully elaborated in the discussion of the four acids. In studying malei'c and the alkylmale'ic acids, the thought will be expressed that in all probability a structure differing widely from that assigned fumaric acid properly falls to malei'c acid and its derivatives. THE CHEMICAL CONSTITUTION OF THE CARBON COMPOUNDS. 51 The structure will be influenced by the configuration. The relations are similar in the case of the coumaric acids (see these). Baeyer considers that the isomerism of the saturated iso- or carbocyclic compounds, as will be more fully explained when the hexahydrophthalic acids are described, bears a definite relation to the stereo-isomerism of the ethylene derivatives. The same author maintains that the simple ring-union of carbon atoms viewed from a stereochcmical standpoint has the same signification as the double union in open chains. Therefore, stereo-isomerism in the carbon compounds with double union would appear merely as a special case of isomerism in simple ring-unions. Baumann applied this idea to saturated heterocyclic compounds to the polymeric thioaldehydes (see these). Baeyer suggested the introduction of a common symbol for all geometrical isomerides ; it was the Greek letter F. The addition of an index will enable one to readily express the kind of isomerism. In the case of compounds which contain absolute asymmetric carbon atoms, the signs -\ can be employed. Thus the expressions Dextro-tartaric Acid = F -f -f- "] Laevo- " " = 7" j- Tartaric Acid Mesotartaric " = / -| j are understood without special explanation. In the case of relative asymmetry in unsaturated compounds and saturated rings, Baeyer proposes to use the terms cis and trans. Maleic Acid=/cis, cis or briefly /'cis ethylene dicarboxylic acid, while fumaric acid = /cis, trans ethylene dicarboxylic acid. The ready formation of iso- or carbocyclic and heterocyclic com- pounds has been attributed to the spacial arrangement of the atoms, in case that five or six atoms take part in the ring formation. Such stereochemical considerations will be duly observed in the introduction to the iso- or carbocyclic compounds, as well as in the introduction to the heterocyclic derivatives, and in the discussion of the cyclic carboxylic esters or lactones, the cyclic acid amides or lactams, the anhydrides of dibasic acids, etc. Hypotheses Relating to Multiple Unions of Carbon. The multiple unions of carbon are important in stereochemical considera- tions, hence there has not been a lack of search into the nature of this union as well as attempts to represent it. All investigations in this direction demonstrate how difficult it is at present to understand so obscure a force as chemical attraction or affinity resting upon a mechanical basis. Despite the demand and necessity that may exist for the introduction of hypotheses dealing with the mechanics of multiple linkage the views thus far presented are in many essentials contradic- tory and not one has won general recognition for itself. See Baeyer, B. 18, 2277; 23, 1274; Wunderlich, Configuration organischer Molecule, Leipzig (1886) ; Lossen, B. 20, 3306; Wislicenus, B. 21, 581; V. Meyer, B. 21, 265 Anm.; 23, 581, 618; V. Meyer und Riecke, B. 21, 946 ; Auvvers, Entwicklung der Stereochemie (Heidelberg 1890), p. 22-35; Naumann, B. 23, 477; Briihl, A. 211, 162, 371 j Deslisle, A. 269, 97 ; Skratip, Wien. Monatsh. 12, 146. Stereochemistry of Nitrogen. Isomeric phenomena of nitrogen-containing compounds of like chemical structure, which could not be ascribed to the same cause 52 ORGANIC CHEMISTRY. as prevailed in carbon compounds, led to the transference of stereochemical views to the nitrogen atom. There appeared to be an " absolute nitrogen asymmetry" corres- ponding to the " absolute carbon asymmetry." Examples of this class existed accord- ing to Le Bel in the unstable, optically active modification of metbyl-ethyl-propyl- isobutyl- ammonium chloride (C. r. 112, 724). The isomerisms of the oximes, according to Hantzsch and Werner, and those of the hydroxamic acids, according to Werner, correspond to the " relative asymmetry " that the doubly-linked carbon atoms are capable of causing. Intramolecular Atomic Rearrangements. Many investiga- tions have shown that certain modes of linking, apparently possible from a valence standpoint, cannot, in fact, occur, or when they do take place are possible only under certain definite conditions. In reactions, for example, in which two or three hydroxyl groups should unite with the same carbon atom, asplitting-off of water almost invari- ably occurs and oxygen unites doubly with carbon, e. g. t / Cl I /" Li \ -H 2 ,0 /~*TT /"* /~*"\ V_ I r~*TJ[ f~* f~\ XT I ^^/"'TU f+&r CH 3 C Cl > CH 3 . C O II ^CH 3 / Q / / " ~~ " \ - H 2 ^O H.C-C1 - - I HC-0-" 0-H/ X ~ H On the other hand, the ethers derivable from these unstable "alco- hols " are stable : CH 3 . C O. C 2 H 5 and O. C 2 H 5 In other cases there is a splitting-off of an halogen hydride, water or ammonia with the production of an unsaturated body, or an anhydride of a dibasic acid, or a cyclic ester (a lactone), or a cyclic amide (a lactani). In these reactions two molecules result from one molecule, in which atom-groups occur in unstable linkage-relations. Together with the organic molecule there is formed a simple inorganic body. However, this course is not the only possible direction of change. On the contrary, by intramolecular atom rearrangement, unstable atomic groupings pass in the moment of their formation into stable forms, the molecular magnitude at the same time not altering. The hydrogen atom especially is inclined to wander. This is also true of other groups: alkyl and phenyl groups. To-day the number of phe- nomena of this class is remarkably large. A few examples, however, will suffice. A free hydroxyl group adds itself in most cases to a car- bon atom in double union with its neighboring carbon atom. When THE CHEMICAL CONSTITUTION OF THE CARBON COMPOUNDS. 53 intramolecular atom-rearrangements occur the hydrogen of the hydroxyl attaches itself to the adjacent carbon atom, and oxygen of hydroxyl unites doubly with carbon (Erlenmeyer's rule, B. 13, 309; 25, 1781). CHBr /CH.OH\ CHO > | Aldehyde. CH 3 CBr - > C.OH /3-Allyl Alcohol. Acetone. However, the ethers obtained from vinyl alcohol (see this) are stable : CH 2 =CHO.C 2 H 5 and CH 2 =C(O.C 2 H 5 ) CH 3 are known. It may also be imagined that a transposition such as that described above can occur by two unstable and similar molecules rearranging with each other, so that two similar stable molecules result : HO.CH=CH 2 OCH.CH 3 An elevation of temperature is necessary to induce many of these reactions. Both compounds are capable of existence. Unsaturated acids pass into lactones. The intramolecular atom-rearrangement proceeds in a direction favoring the formation of a stable ring: (CH 3 ) 2 C JCH 3 ) 2 C O CH CH 2 .CO 2 H CH 2 CH 2 CO Isocaprolactone. In other unsaturated compounds we observe that the unsymmetrical is transformed into asymmetrically formed body through the rearrange- ment of the double linking of carbon : ( H, : CH.CH 2 I - --J- CH 2 : CH.CH 2 .CN > CH 3 .CH : CH.CN-- >- Allyl Iodide. Nitrile of Crotonic Acid. CHa.CHrCH.CO.H Crotonic Acid. CH 8 = C CO CH 3 .C CO CH 2 .C() CH CO Itaconic Anhydride. Citraconic Anhydride. The esters of hydrosulphocyanic acid, under the influence of heat, rearrange themselves into the isomeric mustard oils, sulphur unites 54 ORGANIC CHEMISTRY. doubly with carbon and the alcohol radical that had previously been in union with sulphur links itself to nitrogen : C 3 H 5 S C=N- -^S = C = Allyl Sulphocyanide. Allyl Mustard Oil. Isonitriles or carbylamines, when heated, pass into nitriles; the alcohol radical previously in union with nitrogen, wanders over to carbon : -^C 6 H 5 - C = N. Phenyl Carbylamine. Benzonitrile. Other rearrangements among the atoms of compounds only transpire as the result of the action of an energetic acid or a powerful base. Indifferent bodies pass over into basic and acid compounds: HCl C 6 H 5 or H 2 S0 4 C 6 H 4 . NH 8 Hydrazobenzene (indifferent). Benzidine (diacid base). CO.C 6 H 5 KOH C 6 H 5 r- \C(OH)CO,H CO.C 6 H 5 C 6 H 5 Benzil (indifferent). Benzilic Acid. Pseudo-forms, Pseudomerism (Tautomerism, Desmo- tropy, Merotropy). In most of the intramolecular rearrangements it was the hydrogen atoms that wandered. Alcohol radicals and phenyl groups are prone to do the same. It was in this way that a gradual knowledge that many groups were unstable and stable sprang up. In the case of many bodies it became to be known that apparently they could react in accordance with two different formulas. In other words, as our constitutional formulas were deduced from chemical deportment, it may be said that compounds existed to which two, and under cer- tain circumstances more, constitutional formulas could be ascribed. Baeyer (B. 16, 2188) explained this phenomenon in such a manner that the stable bodies, under heat influence or reagents, passed into unstable modifications. "These isomerides are only known in com- pounds; in the free state they revert to the original form. Their instability is referable to the mobility of the hydrogen atoms, since the replacement of the latter is followed by stability " (compare A. W. Hofmann, B. 19, 2084). Mention may be here made of: O.R o Known. Known. THE CHEMICAL CONSTITUTION OF THE CARBON COMPOUNDS. 55 N \SH Hydrosulphocyanic Isothio- Acid. cyanic Acid. NH =N ^NH, Cyanamide. CH c Carbodi-imide. CH, II or C.OH CO Hydroxyl Ketone Known. cf X NR 2 Known. CHCO 2 C 2 H 5 NR Known (mustard oils.) Known. CH 2 .CO 2 C 2 H 5 C.(OH).CH 3 CO.CH 3 or Enol Form. Form. NH or | :OH co Lactime Lactam Form. Form. J. Acetoacetic Ester. -N e.g. COC.OH Isatine. Baeyer proposes to represent the unstable modifications by the desig- nation " pseudo." Pseudomerism is the term that will be adopted in this work for the phenomenon in which one and the same carbon compound can react in accordance with different structural formulas. The unstable form of a derivative will, therefore, take the name " pseudoform " or "pseudo-modification." In some instances both forms are known. It is noteworthy that most " pseudomeric " compounds are acid in nature; they can form salts. When these salts are treated with alkylogens or acylhaloids the two classes of isomerides appear. H. Goldschmidt (B. 23, 253) refers this phenomenon to the appearance of tree ions. Hence in passing judgment upon questions of pseudomerism only those reactions can be considered, from which electrolytic disso- ciation is excluded. Michael ( J. pr. Ch. 37, 473) offers the thought (and it is worthy of every consideration) that in the transpositions of the salts by organic haloids two independent processes, depending on the conditions present, take place : there is a simple exchange in that the organic radical takes the place of the metal, or the radical haloid first adds itself and subsequently the metallic haloid separates. In the latter case the organic radical assumes a position different from that previously held by the metallic atom (compare acetoacetic ester and malonic ester). Nef has recently main- tained the correctness of Michael's view. Laar, on the contrary (following Butlerow, A. 189, 77, van 't Hoff, Ansichten iiber die organische Chemie 2, 263, and Zincke, B. 17, 3030), assumes that such com- pounds consist of a mixture of structural isomerides, in that an easily mobile hydro- gen atom oscillates bet ween two positions in equilibrio, and thereby the entire complex becomes mobile. He designates the phenomenon as tautomery. Discarding the uncertainty introduced into the classification of the carbon compounds by the accept- ance of this view, it has been noted that carbon compounds which Laar considers mixtures of structurally isomeric bodies do not differ in their physical properties from carbon compounds which offer no place in their structure for this equivocal assump- tion. By the assumption of tautomerism with the underlying meaning assigned it by Laar, the experimental solution of the problem as to the conditions under which 56 ORGANIC CHEMISTRY. pseudo-forms are capable of existence is without object, although from the nature of the case the identification of easily alterable intermediate reaction-products must continue to be one of the most difficult problems, yet success has /been met with in quite a number of cases. The indefatigable labors of Raoul Pictet, made with low temperatures, have brought to light splendid results. These are at the disposition of chemistry, and in the light of these new data the experiments relating to the determination of the conditions under which unstable modifications can exist, deserve to receive careful, renewed attention. The preceding section was prepared in 1893. Since then, numerous confirmations of these views have been found. The ketones constitute the most important class of compounds, which are tautomeric according to Laar. In them, as in acetoacetic ester, the oscillation is between the ketone- and the hydroxyl formula or enol formula. That the ketone formula is present in acetoacetic ester (see this) may be accepted as established. The investigations of Claisen (A. 291, 25), of Guthzeit (A. 285, 35), of W. Wisli- cenus (A. 291, 147), and of Knorr (A. 293, 70) have demonstrated that there exist compounds of the form C(OH) = C CO , which readily pass into the form CO CH CO , and conversely are easily produced from the latter : " The character of the added residue, the temperature and the nature of the solvent, in the case of dissolved substances, determine which of the two forms will be the more I stable." Claisen appears to think that the rearrangement of the group R CO CH into R C(OH) = C will occur more readily, according as the radical R CO is more negative. He designates the acid enol-form the a-compound, and the neutral keto-form the /3-body, e. g. , a-Acetyldibenzoyl methane CH 3 .C(OH) = C(COC 6 H ft ) 2 /3-Acetyldibenzoyl methane CH 3 .CO HC(CO.C 6 H 5 ) 2 . To avoid misunderstandings or confusion it would be better to characterize the a-body by a name, expressing its constitution ; thus, a-methyl-/3-dibenzoyl-vinol. The determination of the molecular refractions (Briihl. J. pr. Ch. [2] 50, 119) and of the magnetic rotations (W. H. Perkin, Sr.) is a most valuable aid in the chemical investigation of such isomerides. While these readily introconvertible isomerides possess an entirely distinct chem- ical character and belong to different classes (alcohols or ketones), bodies exist which, according to their method of formation, appear in two modifications belonging to the same class, yet show themselves to be identical, e. g., diazoamido-compounds, III III amidiiies and formazyl derivatives of the common types R<^ and R\ \NHY ^NY in which R is similar to N in the diazoamido-compounds, to CH in the amidines, and to . N : CH. N : in the formazyl derivatives, while X and Y represent two differ- ent univalent hydrocarbon radicals. Knorr 's methyl pyrazoie (see this) belongs in this category. Following the example of Kekule (compare Constitution of Benzene) this phenomenon has been explained by oscillations or, as Knorr expressed it, by floating Unkings (A. 279, 188) : the imide hydrogen atom is supposed to oscillate between two nitrogen atoms. Briihl proposes the name phasotropy for the phenom- enon itself (B. 27, 2396), while v. Pechmann designates it virtual tautomerism (B. 28, 2362). Akin to the idea of pseudomerism is the idea of desmotropy, derived from (?e<7 ( udf, link, union, and rpeireLv, to change. (P. Jacobson, B. 20, 1732 Anmerk.; 21, 2628 Anmerk.; Hantzsch, B. 20, 2802 ; 21, 1754 ; Forster, B. 21, 1857). Michael suggests the term tnerotropy (J. pr. Ch. [2] 45, 581 Anm.; 46, 208). THE NOMENCLATURE OF THE CARBON COMPOUNDS. 57 THE NOMENCLATURE OF THE CARBON COMPOUNDS. The steadily increasing number of carbon derivatives has shown that definite principles should determine their designation. The absence of general and inter- national rules where they were possible has led to great confusion in the nomenclature. Compounds originating from plants and animals received names that indicated their origin, and often at the same time their characteristic chemical properties: Urea, uric acid, tartar, tartaric acid, formic, oxalic, malic, citric, salicylic acids, etc. \Vith a large class of bodies, e. g., the bases, glucosides, bitter principles, fats, etc., it was customary to employ the ending "ine" : coniine, nicotine, guanidine, creatine, betaine, salicine, amygdaline, glycerine, stearine, etc., and in the terminations al, ol, an, en, yl, ylene, ylidene, the effort was made to show the similarity of certain compounds, without, however, proceeding in a connected way. The more thoroughly the constitution of bodies became known, the greater was the desire to express the manner in which the atoms were united by names. This was especially true in the case of isomeric compounds. The manner in which this was done, however, was left to the choice of the individual, and thus it happened that often one and the same derivative received different names, these being in substance identical. Of the early suggestions on nomenclature that of Kolbe (A. 113, 307) on carbinol deserves special consideration. As is known, Kolbe referred the names of the monohydric. saturated alcohols back to the name carbinol. In order to make this principle more general, we should proceed as follows: Ascertain the carbinol or carbinols for each class of compounds that is, find those bodies from which the homologues might be derived, just as the monohydric, saturated alcohols might be deduced from methyl alcohol or carbinol. Without attempting at this time to deter- mine the limits of the "carbinol nomenclature," it will suffice to remark that in the case of the paraffin dicarboxylic acids all the normal homologues are the carbinols, if I may so call them ; e. g., malonic acid, succinic acid, normal glutaric acid, adipic acid, etc. Indeed, names such as monomethyl malonic acid, ethylmethyl malonic acid, symmetric and unsymmetric dimethyl succinic acid, etc., are so readily under- stood that they are really preferred, and are favorites with many chemists. In 1892 representative chemists of various countries convened in Geneva for the purpose of discussing a nomenclature which would clearly express the constitution of a carbon derivative. The new names adopted by the Geneva Commission will, in the case of certain important series of compounds, be observed in the present text ; they will be enclosed in brackets e.g., [ethene] for ethylene, [ethine] for acetylene, etc. The designations of the simpler bodies the names justified from an historical standpoint and deduced from important reactions will not be wholly eliminated. Thus, the names ethyl hydride, dimethyl or methyl methane will be used for ethane, depending upon what relations are to be especially emphasized. The new nomenclature proceeds from, or begins with, the hydrocarbons. The name of the hydrocarbon serves as the root for the names of those substances which contain their carbon atoms arranged in a similar manner. The different classes of bodies are distinguished by the addition of suffixes to the names of the hydrocarbons. Alcohols end in 0/, aldehydes in - C 6 H 4 C1.CH, /- TT r-tr C1 2 / Ordinary temp. C 6 H 5 .CH 3 At iio-iii Numerous analogous observations are known. C 6 H 5 .CH 2 C1. In general, carbon compounds are much less stable under the influ- ence of heat than the inorganic bodies. When the qualitative examination of organic bodies was discussed, mention was made that many carbon compounds decomposed with the separation of carbon under the influence of heat. Other compounds, when heated at the ordinary temperature, rearrange themselves without alteration of their molecular magnitude, while some polymerize. Compounds, volatilizing undecomposed at ordinary pressure, decompose when their vapors are conducted through tubes heated to redness, and, as a rule, new bodies are formed together with partial carbonization. The splitting-off of hydrogen, the halogens, haloid acids, water and ammonia leads to a more intimate union of the already combined carbon atoms, and carbon atoms which previously were not united with one another not infrequently combine to yield carbocyclic and heterocyclic bodies. Pyrocondensations result (B. n, 1214). In the special part of this volume such results from heat action will be so frequently encountered that it is not necessary to present exam- ples of the special kinds of reactions at this time. It may suffice to mention coal-tar; it contains the liquid bodies formed by the decomposition of coal under the influence of heat. This starting-out material is important both for the development of scientific, theoretical organic chemistry, as well as for technical chem- istry (coal-tar industry). It is mainly composed of carbo- and het- erocyclic compounds, stable under the influence of heat : 66 iog 1410 Benzene. Naphthalene. Anthracene, Phenanthrene. C 4 H 4 S C 5 H 5 N C 9 H 7 N C ]3 H 9 N Thiophene. Pyridine. Quinoline and Isoquinoline. Acndine. 2. ACTION OF LIGHT. Light exerts a great influence upon carbon compounds. The well- known reactions of this kind in the field of inorganic chemistry have corresponding cases in the province of organic chemistry. Light is able to bring about the decomposition, the rearrangement, and the syn- thesis of carbon bodies. Just as the haloid salts of silver decompose with silver deposition, so, too, the alkyl iodides separate iodine under the influence of light. Hence their colorless solutions gradually become yellow and finally dark brown in color. ACTION OF LIGHT. 75 Ethyl mercuric iodide breaks down into mercurous iodide and butane. Experience teaches that many other carbon derivatives decompose more or less rapidly when they are exposed to sunlight. Hence they must be preserved in the dark or in vessels constructed from brown colored glass, which absorbs the chemically active rays of sunlight. It is technically important that an organic dye should resist the influence of light. Most of them are not fast colors, they are, on the contrary, bleached by light. Of the decomposition -reactions produced by sunlight mention may be made of the transposition shown by succinic acid, mixed with uranic oxide ; it splits off carbon dioxide and propionic acid results (A. 133, 253) : C0 2 H. CH 2 . CH 2 . C0 2 H = CO 2 + CH 3 .CH 2 . CO 2 H . Solutions of tartaric acid and citric acid, mixed with uranic oxide, are similarly de- composed by sunlight (A. 278, 373). On exposing anthracene (see this) in benzene solution to sunlight it passes into a polymeric modification, phenanthracene. The combination of carbon monoxide and chlorine, forming carbonyl chloride or phosgene (Davy) is analogous to the complete union of hydrogen and chlorine, form- ing hydrogen chloride, in sunlight : H 2 + C1 2 = 2HC1 ; CO + C1 2 = COC1 2 . The action of chlorine upon marsh gas (p. 82), formaldehyde (B. 29, R. 88), and other carbon derivatives which can be substituted is much influenced by sunlight. The experiments conducted by Klinger show that the chemical action of sunlight is susceptible of more extended application than it has yet found, and that compounds can be produced by it, which could only be prepared in the ordinary chemical way by most powerful or refined means. He found that ethereal solutions of benzoquinone, benzil, and phenanthraquinone are reduced with the formation of aldehyde. Further, that acetaldehyde, isovaleraldehyde, and benzaldehyde unite, under the influence of sunlight, with phenanthraquinone in accordance with the equation : C 6 H 4 .CO C 6 H 4 .CO.COCH 3 | | +CH 3 COH= | || C 6 H 4 .CO C 6 H 4 .COH Phenanthra- Acetaldehyde. Monacetyl phenanthren- quinone. , hydroquinone. Isovaleraldehyde and benzaldehyde also unite directly with benzoquinone, but in a still more striking manner, in that a nucleus-synthesis (p. 85) results. With benzal- dehyde the reaction proceeds as follows : C 6 H 4 2 + C 6 H 5 .COH = C 6 H 5 .CO.C 6 H 3 (OH), Benzo- Benz- Dioxybenzophenone isomeric with the quinone. aldehyde, expected Monobenzoyl hydroquinone. o-Nitrobenzylidene acetophanone in ethereal solution is changed by sunlight to in- digo and benzoic acid (Engler and Dorant, B. 28, 2497) : f [i]COCH=CH.C 6 H 5 f [i] CO CO [i] ] 2C 6 H 4 =C 6 H 4 / c = c v C 6 H 4 +2C 6 H 5 C0 2 H l[2]XO a 4 j[ 2 ]NH/ \NH[2]J The study of these reactions promises much for the interpretation of the chemical changes occurring in plants. 7 6 ORGANIC CHEMISTRY. 3. ACTION OF ELECTRICITY. The actions of electricity upon organic bodies have not been well investigated. Some of the reactions induced by the aid of this agent possess great value for synthetic, organic chemistry. The only method which will cause the union of free hydrogen with free chlorine, consists in the action of the electric spark upon the two elements. Berthelot showed that carbon and hydrogen combined to acetylene on passing the electric spark over carbon points in an atmosphere of hydrogen : 2C + H 2 = CH = CH. Fig. 9 represents the apparatus in which this important synthesis was carried out (A. chim. phys. ; [4] 13, 143; B - 2 3 l6 3 8 )- FIG. 9. Acetylene and nitrogen (A. 150, 60) under the influence of electric discharges, as well as cyanogen and hydrogen, unite to yield prussic acid (C. r. 76, 1132), and carbon monoxide and hydrogen form methane (Brodie, A. 169, 270). CH HI CN | + H 2 = 2CNH ; CN CO 4- 3H 2 = CH 4 4- H 2 O. On the other hand, Kolbe decomposed the aqueous solutions of the potassium salts of monobasic carboxylic acids, especially potassium acetate, by the electric current, and thus prepared dimethyl or ethane. The following equation represents the breaking-down of the potassium acetate : CH.jCO, CH.JCO, K HOiH CH, '+ + + H f CO, KOHTH Kekul6 applied this reaction to the saturated dicarboxylic acids, e. ., succinic acid. Later he and Aarland used it with the unsaturated dicarboxylic acids : fumaric acid, male'ic acid, mesaconic acid, citraconic acid, and itaconic acid (A. 131, 79; J. pr. Ch. [2] 6, 256; 7, 142), with the production of such unsaturated hydrocarbons as ethylene, acetylene, allylene. Kolbe and Moore obtained ethylene dicyanide from cyanacetic acid (B. 4, 519). Crum Brown and J. Walker included the potassium salts of the acid esters of the dicarboxylic acids in the circle of these CLASSIFICATION OF THE CARBON COMPOUNDS. 77 reactions, thus obtaining the neutral esters uf dibasic acids, e.g., potassium ethyl - malonate yielded succinic diethyl ester (A. 261, 107; B. 24, R. 36 ; A. 274, 4*1 ; B. 26, R. 369, 380). In the electrolysis of an alcoholic solution of sodium malonic diethyl ester Mulliken obtained ethane tetracarboxylic ester (B. 28, R. 450). For the electrolytic reduction of aromatic nitro-bodies consult B. 28, 2349; 29, 1390; see also p-amido-phenol. CLASSIFICATION OF THE CARBON COMPOUNDS. The chemical union of the carbon atoms and the character of the groups resulting from this is the basis of the division of the carbon derivatives into two principal classes: the fatty or aliphatic sub- stances (from ahiyap, fat) the chain-like or acyclic carbon derivatives or the methane derivatives, and the cyclic compounds of carbon. The name of the first class is borrowed from the fats and fatty acids comprising it. These were the first derivatives accurately studied. It would be better to name them marsh gas or methane derivatives, inas- much as they all can be obtained from methane, CH 4 . They are further classified into saturated and unsaturated compounds. In the first of these, called also limit compounds or paraffins, the directly- united quadrivalent carbon atoms are linked to each other by a single affinity. The number of n carbon atoms possessing affinities capable of further saturation, therefore, equals 2n -|- 2 (see p. 38). Their general formula is C n X 2n + 2 . Here X represents the affinities of the elements or groups directly combined with carbon. The unsaturated compounds result from the saturated by the exit of an even number of affinities in union with carbon. According to the number of affinities yet capable of saturation, the series are distinguished as C n X 2n ,C n X 2n _2, etc. The methane derivatives contain open carbon chains, the cyclic derivatives contain closed chains, or carbon rings. When carbon atoms alone have formed the ring, the resulting bodies are designated carbo-cyclic compounds. The most important of these ring-shaped bodies is the ring contain- ing six carbon atoms with six free valences. All the aromatic or benzene compounds are derived from it. The importance of this group has gained for it a special position in the chemistry of carbon derivatives. Compared with the aliphatic compounds they manifest such great differences in chemical deportment that they were formerly regarded as a second class of organic bodies, and as such were placed opposite to the first class or aliphatic substances. With the advances in organic chemistry numerous compounds were being constantly discovered, which it is true contained ring-shaped carbon atoms, but in chemical deportment approached the fatty bodies more closely than the aromatic derivatives. In the so-called hydro- 7$ ORGANIC CHEMISTRY. aromatic compounds the more pairs of hydrogen atoms which attach themselves to the benzene nucleus in them, the greater will they resemble, in chemical character, the aliphatic derivatives. Even more closely allied to the latter are those substances which contain a ring consisting of three, four, or five carbon atoms the trimethylene derivatives, tetramethylene derivatives, pentamethylene derivatives. These constitute the passage from the aliphatic bodies to the hydro- aromatic compounds, to which the aromatic derivatives attach them- selves. There are many carbon compounds which contain " rings." In the formation of the latter not only carbon atoms, but also oxygen, sulphur, and nitrogen atoms have taken part. Such bodies have been termed heterocyclic compounds (from Urspos, foreign). As a rule, these derivatives will be discussed at the conclu- sion of the remarks on the open chain bodies, from which they are derived by the exit of water, hydrogen sulphide, or ammonia, and to which they can again be changed. A large class of heterocyclic bodies, more especially thiophene, discovered by Victor Meyer, then the parent substances of the plant alkaloids pyridine, quinoline, isoquinoline, etc., like the aromatic bodies, possess a very stable ring. It may be said in the case of many heterocyclic compounds that the substances with open chains from which they may be theoretically deduced do not really exist. Therefore such heterocyclic compounds will be purposely set to one side and be discussed after the carbo- and isocyclic derivatives. The divisions of the chemistry of the com- pounds of carbon would then be : I. Fatty Bodies : Aliphatic compounds, methane derivatives, chain-like or acyclic carbon derivatives. II. Carbocyclic Compounds. III. Heterocyclic Compounds. i. FATTY COMPOUNDS, ALIPHATIC SUBSTANCES OR METHANE DERIVATIVES, CHAIN-LIKE OR ACYCLIC CARBON DERIVATIVES. i. HYDROCARBONS. The hydrocarbons may be regarded as the parent substances from which all other carbon compounds arise by the replacement of the hydrogen atoms by different elements or groups. The outlines of the linking of carbon atoms were presented in the HYDROCARBONS. 79 introduction (p. 37). We distinguish, therefore, (i) saturated and (2) unsaturated hydrocarbons . The first only contain singly linked carbon atoms, while the unsaturated contain pairs of carbon atoms united doubly and trebly. As the first series has attained the limit of saturation by hydrogen, they are frequently called the limit hvdro- carbons, or, after the first member of the series : marsh gas the methane hydrocarbons. The limit hydrocarbons are not very reactive, but they are very stable ; hence their designation as paraffins (from parum afifinis). A. Saturated or Limit Hydrocarbons, Paraffins, Alkanes, Marsh Gas or Methane Hydrocarbons, C n H 2n + 2 . Nomenclature and Isomerism. In consequence of the equivalence (confirmed by facts) of the four affinities of carbon (see p. 37) no isomerides are possible for the first three members of the series (- n H 2n + 2 CH 4 CH 3 CH 3 CH 3 CH 2 CH 3 Methane. Ethane. Propane. Formerly. these hydrocarbons were designated the hydrides of univa- lent radicals hydrocarbon residuesor alkyls : methyl, ethyl, propyl, etc. Combined with the water residue or hydroxyl, they yielded the alcohols C n H 2 n+iOH. They were at first obtained from compounds of these radicals with other elements or groups; hence the names methyl hydride for methane, ethyl hydride for ethane, etc. The obtainable and first known derivatives of the alkyls C n H 2n +i were their hydroxyl derivatives or the alcohols, e. g., C 2 H 5 .OH, ethyl alcohol, and their halogen ethers. At the suggestion of A. W. Hofmann their names were formed later by replacing the final syllable " yl " of the alkyls by the final syllable "ane," so that methane was used for methyl, ethane for ethyl, propane for propyl, etc., and for the homologous series the name alkanes was adopted. Two structural cases exist for the fourth member, QH 10 : X CH 3 CH 3 CH 2 CH 2 CH 3 and CH CH 3 Normal Butane. X CH 3 Trimethylm'ethane. (Isobutane.) In the name trimethylmethane for isobutane, isomeric with normal butane, is indicated that this substance is derived from methane by the replacement of three hydrogen atoms by three methyl groups. For the fifth member, pentane, C 5 H 12 , three isomerides are possible : /CH 3 CH, CH, CH 2 CH, CH 3 Normal Pentane. ^CH 2 . CH, Dimethyl-ethyl Methane. ancl CH 3 CH 3 \/-/ Tetramethyl Methane. / \ CH 3 CH, 8o ORGANIC CHEMISTRY. The number of theoretically possible isomerides now increases rapidly. Hexane, C 6 H 14 , has 6 isomerides ; heptane, C 7 H 16 , 9 isomerides; octane, C 8 H 18 , 1 8 isomerides; tridecane, C 13 H 28 , 802 isomerides (B. 8, 1056; B. 13, 792). Commencing with the fifth member, the names are formed from the Greek words representing numbers. The "Geneva Commission" recommends the retention of the ending " ane," as first suggested by A. W. Hofmann (J. 1865, 413), for the hydrocarbons CaH. z n-^ 2 . The hydrocarbons with branched carbon chains are considered alkyl substitution products of the normal hydrocarbons already contained in their formulas, and the carbon atoms of this normal hydrocarbon are numbered. The numbering is begun with that carbon atom to which the side-chain is adjacent : (1) (2) (3) (4) (5) CH 3 .CH.CH 2 .CH 2 .CH 3 = [Methyl- 2-pentane]. CH 3 The carbon atoms of a longer substituting radical are also numbered, and, indeed, with two numbers. First, each atom is marked by the number indicating the place where the side-chain is attached to the normal chain ; second, with particular numbers, beginning with the carbon atom joined to the central or main chain as number one. Furthermore, should an alcohol radical attach itself to the middle carbon atom of the side- chain, then the expressions for the substituting radical are-^- Metho-, etho-, etc., instead of methyl-, ethyl-, etc. : (1) (2) (3) (4) (5) (6) (7) CH 3 . CH 2 . CH 2 . CH . CH 2 . CH 2 . CH 3 = [Metho-4 1 -ethyls-heptane]. (4 1 )CH-CH 3 (4 2 ) CH 3 The variation in structure of the carbon chain, or carbon nucleus, is the cause of isomerism in the paraffins. This type of isomerism is called chain- or nucleus-isomerism (p. 43). Methods of Formation and Properties of the Paraffins. The limit hydrocarbons are formed in the dry distillation of wood, turf, lignite, bituminous coal, and bog-head and cannel coal, rich in hydro- gen; hence they are present in illuminating gas and in the light oils of coal-tar. They occur already formed in petroleum, particularly that from America, which consists almost exclusively of them, and contains all of them from methane to the highest. It is difficult to isolate the individual hydrocarbons from such mixtures. Before advancing to the* general methods used in the preparation of the paraffins methods by which the individual hydrocarbons can be easily obtained in pure con- dition it will be best to discuss the two important members, methane and ethane. (i) Methane, CH 4 (Methyl hydride), is produced in the decay of organic substances; therefore disengaged in swamps (marsh gas) and mines, in which, mixed with air, it forms fire-damp. HYDROCARBONS. 8 1 In certain regions, like Baku in the Caucasus and the petroleum districts of America, it escapes, in great quantities, from the earth. It is also present, in appreciable amount, in illuminating gas. The synthesis of methane, the simplest hydrocarbon, from which all the fatty bodies may be derived, is particularly' important. By the synthesis of a carbon derivative is understood its formation from the elements, or from such carbon derivatives which can be obtained from the elements. Under proper conditions hydrogen and carbon may be directly combined, with the production, however, of acety- lene CH = CH (p. 76), and not methane. The latter can be obtained ( i) from carbon disulphide CS 2 (which may be made directly from its constituents) if the vapors of this volatile substance, mixed with hydrogen sulphide gas, be passed over red-hot copper (Berthelot) : Or (2) the carbon disulphide is converted by chlorine into carbon tetrachloride CC1 4 , and this reduced, by nascent hydrogen (sodium amalgam and water) : CS 2 -|- 3C1 2 = CC1 4 -f S 2 C1 2 ; CC1 4 -f 8H = CH 4 -f 4HC1. (3) Methane is also formed from carbon monoxide and hydrogen, if the mixture of gases be exposed in an induction tube to the action of electricity (p. 76, A. 169, 270) : 2 C-fO 2 =2CO; CO + 3H 2 =:CH 4 -f H 2 O. (4) Aluminium carbide is decomposed, in the cold, by water, forming methane and aluminium hydroxide (B. 27, R. 620) : C 3 A1 4 -f I2H 2 O = 2CH 4 -f 2A1 2 (OH) 6 . Methyl alcohol, or wood-spirit, CH 3 .OH, can be converted into methane by first changing it to methyl iodide, and then (5) reducing the latter with nascent hydrogen (from moist zinc-copper), or with zinc dust in the presence of alcohol (B. 9, 1810) ; or (6) by preparing zinc methyl from methyl iodide and decomposing it with water : CH 8 . OH - ^ CH 3 I + 2H '= CH 4 -f- HI CH,, 7 , HOH CH 4 , 7 .OH CH' >Zn + HOH = CH 4 + Zn /.n + TT^TT = r tr TT + ^tt furl), (rrankland). ~ 2 --5 rlL/rl ^jjilg. rl Or (4) mercury ethide may be decomposed by concentrated sulphuric acid : (C 2 H 5 ) 2 Hg -f SO 4 H 2 = 2C 2 H 5 . H -f SO.Hg (Schorlemmer). These last three methods led to the assumption that ethane was ethyl hydride. The following reactions show how ethane can be formed from the union of two methyl residues, and hence led to the view that the hydrocarbon was dimethyl. (5) Sodium is allowed to act upon methyl iodide, or (6) zinc methide may be substituted for the metal : 2CHJ + 2Na = CH 3 CH 3 -f 2 Nal. (Wiirtz). 2CH 3 I -f (CH 3 ) 2 Zn = 2 CH 8 CH S + ZnI 2 . HYDROCARBONS. 83 A more convenient method (7) consists in heating acetic anhydride with barium dioxide : 2 (C,H 3 0) 2 -f Ba0 2 = C 2 H 6 -f (C,H 3 O 2 ) 2 Ba -f 2 CO 2 . From a theoretical point of view (8) the electrolysis of a concen- trated solution of potassium acetate (p. 76) (the method used by Kolbe (1848) when he discovered ethane), is of great importance. The salt breaks down into potassium, its electro-positive constituent, ap- pearing at the negative pole and separating hydrogen from water at that point, and also the unstable radical CH 3 .CO 2 , which immediately decomposes at the electro-positive pole into CH 3 and CO 2 . Two methyl groups then unite to dimethyl, just as two hydrogen atoms combine to form a molecule of that element : CH, ; CO, CH 3 I CO 2 K HO i H CH H K HO ; H CH 3 2KOH | H Both Kolbe and Frankland believed that ethyl hydride C 2 H 5 .H differed from dimethyl CH 3 .CH 3 . Such a difference was not possible in the light of the valence theory. By converting the hydrocarbon from (C 2 H 5 ) 2 Hg and that obtained in the elec- trolysis of potassium acetate into the same ethyl chloride Schorlemmer (1863) proved the identity of ethyl hydride C 2 H 5 .H and dimethyl CH 3 .CH 3 , thus confirming a fundamental requirement of the valence theory : (C 2 H 5 ) 2 Hg - - ^ C 2 H 5 .H 2 CH 3 .CO OK_ >CH 3 .CH 3 _ _ > CH 8 CH 1 C1. Ethane is a colorless and odorless gas. Its critical temperature equals +34 an d its critical pressure is 50.2 atmospheres. It boils at 93 under 760 mm. pressure. The specific gravity of liquid ethane at o is 0.466 (B. 27, 3305). It acts like methane toward solvents. Ethane can be converted into ethyl'alcohol through its monochlor- substitution product. Homologues of Methane and Ethane. In preparing the homologous paraffins the homologues of ethyl alcohol C n H 2n + ,.OH and the saturated fatty acids are used. I. Formation from compounds containing a like number of carbon atoms. (1) From the unsaturated hydrocarbons by the addition of hydrogen (see Ethane). (2) By the reduction of alcohols, ketones, and carboxylic acids. (a) The alcohols, for example ethyl alcohol, are first changed to chlorides, bromides, and iodides, and then reduced with nascent hydrogen, from zinc and hydrochloric acid, or from sodium amalgam and alcohol. The iodides can also be treated with aluminium chloride (B. 27, 2766). 84 ORGANIC CHEMISTRY. Thus propane has been prepared from the two propyl iodides, C 3 H 7 I, and trimethyl methane from the iodide of tertiary butyl alcohol by means of zinc and hydrochloric acid. (b) The saturated fatty acids, C n H 2n + i.CO 2 H, particularly the higher members of the series, may be converted into the corresponding paraffins by heating them with concentrated hydriodic acid and red phosphorus to 200-250 : C 17 H 35 .C0 2 H + 6HI = C 18 H 38 + 3 I 2 + 2 H 2 O. Stearic Acid. Octadecane. (c) The ketones (see these) , resulting from the distillation of the calcium salts of fatty acids, change to paraffins when they are heated with hydriodic acid. It is more practical to first prepare the keto-chlorides (p 102) by the action of phosphorus penta- chloride upon the ketones, and then reduce these. The last two reactions especially were applied (B. 15, 1687, 1711; 19, 2218) in the preparation of the normal hydrocarbons from nonane, CH 3 (CH 2 ) 7 CH 3 , to tetra- cosane CH 3 (CH 2 ) 22 CH 3 . (3) Or, the alcohol is changed by an alkyl iodide into a zinc or mer- cury alkyl, and the zinc alkyls are then decomposed by water (see Methane and Ethane), and the mercury alkyls by acids (see Ethane). The iodides of the radicals may be heated with zinc and water, in sealed tubes, to 120-180. II. Formation from compounds rich in carbon, by the splitting- off of carbon. (4) A mixture of the salts of fatty acids (the carboxyl derivatives of the alkyls) and sodium or potassium hydroxide is subjected to dry dis- tillation (see Methane). Soda-lime is preferable to the last reagents. When the higher fatty acids are subjected to this treatment the usual products are the ketones ; hydrocarbons, however, are produced when sodium methylate is used (B. 22, 2133). The dibasic acids are similarly decomposed : ,CO 2 .Na C 6 H 12 ( -f 2NaOH = C 6 H 14 + 2 CO 3 Na 2 . III. Methods of Formation, consisting in the union of alkyls, previ- ously not directly combined, with one another. (5) Method of Wiirtz : Action of sodium (or reduced silver or copper) upon the bromides or iodides of the alcohol radicals in ethereal solution (see Ethane). Thus with sodium : C 2 H 5 I yields C 2 H 5 . C 2 H 5 Diethyl or normal butane. CH 3 CH 2 CH 2 I C 3 H 7 . C 8 H 7 Dinormal propyl or normal hexane. CH 3 CH 2 CH 2 CH 2 I " C 4 H 9 . C 4 H 9 Dinormal butyl or normal octane. This reaction proceeds especially easy with normal alkyl iodides having high molecular weights. Thus, Hell and Hagele, by fusing myricyl iodide with sodium, obtained hexacontane, C 60 H 122 , a compound having by far the longest normal carbon chain (B. 22, 502). By using a mixture of the iodides of two primary alcohols hydrocarbons result from the union of different radicals. The iodides of optically HYDROCARBONS. 85 active (p. 46) alcohols, e.g., optically active arayl iodide, yield optically active paraffins (B. 27, R. 852). (6) Action of zinc alkyls upon alkylogens (see Ethane) and ketone chlorides. Thus, acetone chloride or /3-dichlorpropane is changed by zinc methide into tetra- methyl methane : CH 3 CH 3 V ' A - 1 3 Acetone. Acetone Chloride. -3>C( (7) By the electrolysis of the alkali salts of fatty acids (see Ethane). Synthetic Methods. The last group of reactions comprises synthetic methods, serving for the building up of hydrocarbons. In the formation of methane from carbon disulphide and hydrogen sul- phide it was explained what in general was understood by the synthesis of a carbon compound. Those reactions in which carbon atoms, not before combined with one another, are united claim particular import- ance in the synthesis of the compounds of carbon (Lieben, A. 146, 200). Most of the carbon derivatives are due in the first place to the combining power of the carbon atoms among themselves. Such reactions are the synthetic methods of organic chemistry in the more restricted seYise. In the future we shall designate them nucleus- synthe- ses. They genetically bind together the members of an homologous series, and the homologous series among themselves, and carry the open carbon chains into closed chains or rings. The synthesis of a carbon compound from derivatives of carbon of known structure is important for the recognition of its structure or constitution; indeed, it is one of the most important aids. Properties of the Paraffins. The lowest members of the series up to butane and tetramethyl methane are gases at the ordinary temperature. The middle members are colorless liquids, with a faint but character- istic odor. The higher representatives, beginning with hexadecane, C 16 H 34 , melting at 18, are crystalline solids. The highest members are only volatile without decomposition under reduced pressure. The boiling points rise with the molecular weights ; the difference for CH 2 is at first 30, and with the higher members it varies from 25-13. The boiling points of propane, of the two butanes, the ihrzepenfanes, and the five known hexanes are given in the following table. All the theoretically possible isomerides are known : Boiling point below Structural Formula. 760 mm. C 3 H 8 Propane CH 3 .CH 2 .CH 3 4 5( 6.27,3306). C 4 H 10 Normal Butane CH 3 .CH 2 .CH 2 .CH 3 + i(B.27,2768). Trimethyl Methane CH 3 .CH(CH 3 ) 2 17 C 5 H 12 Normal Pentane CH 3 .(CH 2 ) 3 .CH 3 +38 Dimethyl-ethyl Methane CH 3 .CH 2 .CH(CH 3 ) 2 -(-30 Tetramethyl Methane C(CH.\ + 10 C 6 H U Normal Hexane CH 3 (CH,) 4 CH 3 +71 Methyl diethyl Methane CH 3 (C 2 H 5 ) 2 CH + 64 Dimethylpropyl Methane CH 3 .CH 2 .CH 2 .CH(CHA, +62 I >i-isopropyl (CHgVCPT.CHXCHJ.,* .+ 58 Trimethyl ethyl Methane CIf 3 .Crt 2 .C(CH 3 ) s + 43 4* 86 ORGANIC CHEMISTRY. It is evident from this presentation that among isomerides those with normal structure (p. 42) have the highest boiling points. A general rule would be that with the accumulation of methyl groups in the molecule the boiling points of isomeric bodies are lowered. The same regularity will be again encountered in other homologous series. The subjoined table contains the melting points, boiling points, and the specific gravities of the known normal paraffins : Heptane, . . . , Octane, .... Nonane, .... Decane, .... Undecane, . . . Dodecane, . . . Tridecane, . . . Tetrad ecane, . . Pentadecane, . . Hexadecane, Heptadecane, . Octadecane, . . Nonadecane, . . Eicosane, . . . Heneicosane, . . Docosane, . . . Tricosane, . . . Tetracosane, . . Heptacosane,. . Hentriacontane, Dotriacontane, . Pentatriacontane, Dimyricyl, . . . C 7 H 16 cXo ?lf C 32 H 66 Melting Point. -51 -32 26.5 12 6.2 + 5-5 + 10 + 18 + 22.5 -f 28 + 32 + 36.7 + 40.4 + 44-4 + 47-7 + 59'-5 + 68.1 -f 70.0 + 74-7 -j- 102 B. P. Sp. Gr. 98.4 0.7006(0) 125-5 0.7188(0) 149-5 0-7330(0) u r 173 0.7456(0) 3 194-5 0-7745] . 8 214 0773 |ri o. 234 0-775 s 252.5 0-775 270.5 0-775 & 287.5 0-775 i> 303 0.776 T3 3i7 0.776 I 330 0.777 ! at their oJ f 205 0.777 m. p. 3 215 0.778 (fi 6 224.5 0.778 a 234 0.778 5 . 243 0.778 1 270 0.779 E 302 0.780 u -o 310 0.781 s 33i 0.781 J The limit hydrocarbons are insoluble in water. The lower and intermediate members are readily soluble in alcohol and ether. The solubility in these last two solvents falls with increasing molecular weight. Dimyricyl, C^Hj^, melting at 102, is scarcely soluble in them. The specific gravities of the liquid and solid hydrocarbons increase with their molecular weights, but are always less than that of water. It is remarkable that in the case of the higher members the specific gravities at the point of fusion are almost the same. They rise from 0.773 f r dodecane, C 12 H 26 , to but 0.781 for pentatri- acontane, C 35 H 72 ; consequently the molecular volumes are nearly proportional to the molecular weights (B. 15, 1719; A. 223, 268). The paraffins are not absorbed by bromine in the cold or sulphuric acid, being in this way readily distinguished and separated from the unsaturated hydrocarbons. They are not very reactive and are very stable, hence, their designation as paraffins. Fuming nitric acid and even chromic acid are without much effect upon them in the cold; when heated, however, they generally burn directly to carbon dioxide and water. Recently, n-hexane and n-octane have been nitrated by heating them with dilute nitric acid. When acted upon by chlorine or bromine they yield substitution products. By means of the latter the paraffins can easily be converted, as ob- served under methane and ethane, into other derivatives. HYDROCARBONS. 87 Technical Preparation of the Limit Hydrocarbons. The hydrocarbons, technically accessible, are applied in remarkably large quantities for illumination and heating purposes. They are also used as solvents for fats, oils, and resins, and as lubricants for machinery; finally, as salves. The great abundance of petroleum, rock-oil (naphtha), is of the ut- most importance to chemical industry. It is especially abundant in Pennsylvania and Canada, although it is also found in the Crimea along the Black Sea, and at Baku on the shore of the Caspian, as well as in Hungary, Galicia, Roumania, and the Argentine Republic. Its occurrence in Germany, in Hannover, and in Alsace is limited. Since the year 1859 efforts have been put forth to work oil wells, which have been known for many years, and also to make new borings. (See Hofer: Das Erdol and seine Verwandten, 1888.) The following data give some idea of the vast quantities in which this product is handled : In 1889 the yield of crude oil in America was about 35,000,000 barrels ; in Russia, about 21,000,000 barrels ; in other countries, 1,700,000 barrels, of which Alsace furnished 45,000 barre's and Hannover 6000 barrels. The barrel contains 159 liters. The consumption in Germany represented about 4,000,000 barrels (see F. Fischer, Hctb. d. ch. Technologic, 1893, S. 128). In a crude state it is a thick, oily liquid, of brownish color, with greenish luster. Its more volatile constituents are lost upon exposure to the air; it then thickens and eventually passes into asphaltum. The greatest differences prevail in the various kinds of petroleum. It is very probable that petroleum has been produced by the distillation of the fatty constituents of fossil animals. This took place under great pressure and by the heat of the earth. The distilla- tion of fish blubber under pressure has yielded products very similar to the American petroleum (Engler, B. 21, 1816 ; 26, 1449; Ochsenius, B. 24, R. 594). At the conclusion of his investigations on metallic carbides Moissan shows that on decomposing the metallic carbides in the interior of the earth with water hydrocarbons might arise, and these could cause the gas and petroleum wells (B. 29, R. 614). American petroleum consists almost exclusively of normal paraffins ; yet minute quantities of some of the benzene hydrocarbons (cumene and mesitylene) appear to be present. In a crude form it has a specific gravity of 0.8-0.92, and distils over from 30-360 and beyond this. Various products, of technical value, have been obtained from it by fractional distillation: Petroleum ether, specific gravity 0.665-0.67, distilling about 50-60, consists of pentane and hexane ; petroleum benzine, not to be confounded with the benzene of coal tar, has a specific gravity of 0.68-0.72, distils at 70-90, and is composed of hexane and heptane ; ligrolne, boiling from 90-! 20, consists princi- pally of heptane and octane ; refined petroleum, called also kerosene, boils from 150-300 and has a specific gravity 01*0.78-0.82. (For the apparatus of Engler and Abel intended to determine the flashing point ORGANIC CHEMISTRY. of petroleum see Eisner : Die Praxis des Chemikers [1893] S. 399, 401; B. 29, R. 553). The portions boiling at high temperatures are applied as lubricants; small amounts of vaseline and paraffins (see below) are obtained from them. Caucasian petroleum (from Baku) has a higher specific gravity than the American ; it contains far less of the light volatile constituents, and distils about 150- Upward of IO per cent, benzene hydrocarbons (C 6 H g to cymene C 10 H ]4 ) may be extracted by shaking it with concentrated sulphuric acid ; and in addition less saturated hydro- carbons, C n H 2n _ 8 , etc. (B. 19, R. 672). These latter are also present in the German oils (Naphthenes, B. 20, 595). That portion of the Caucasian petroleum insoluble in sulphuric acid consists almost exclusively of C n H 2n hydrocarbons, the naphthenes, which belong to the cycloparaffins (p. 89), and are probably chiefly pentamethylenes, mixed, perhaps, with aromatic hydrides ; hexahydroxylene octo- naphthene, hexahydromesitylene=non-naphthene (B. 16, 1873; 18, R. 186; 20, 1850, R. 570). From its composition, Galician petroleum occupies a position inter- mediate between the American and that from Baku (A. 220, 188). German petroleum also contains benzene hydrocarbons (extracted by sulphuric acid), but consists chiefly of the saturated hydrocarbons and naphthenes (Kraemer, B. 20, 595). The so-called petrolic acids are present in all varieties of petroleum, particularly that from Russia (Beilstein, Hdb. d. org. Ch., Ill Aufl. , 522). Products similar to those afforded by American petroleum are yielded by the tars resulting from the dry distillation of cannel coal (in Scotland) and a variety of coal found in Saxony. These tars contain appreciably greater quantities of unsaturated hydrocarbons associated with the naphthenes and paraffins, as well as the aromatic hydrocarbons present in the tar from bituminous shales (Heusler, B. 28, 488; Z. f. anorg. Ch. 1896, S. 319). Large quantities of solid paraffins are also present in these tar oils. By paraffins, we ordinarily understand the high -boiling (beyond 300) solid hydrocarbons arising from the distillation of the tar obtained from turf, lignite, and bituminous shales. Paraffin was dis- covered by Reichenbach (1830) in the tar from beech-wood. They are more abundant in the petroleum from Baku than in that from America. Mineral wax, ozokerite (in Galicia and Roumania; also upon an island in the Caspian Sea, B. 16, 1547) and neftigil (in Baku), are examples existing in a free, solid condition. For their purification the crude paraffins are treated with concentrated sulphuric acid, to destroy the resinous constituents, and then re-distilled. Ozokerite that has been directly bleached, without distillation, bears the name ceresine, and is used as a substitute for beeswax. Paraffins that liquefy readily and fuse between 30-40, are known as vaselines; they find application as salves. When pure, the paraffins form a white, translucent, leafy, crystalline mass, soluble in ether and hot alcohol. They melt between 45 and 70, and are essentially a mixture of hydrocarbons boiling above 300, but appear to contain also those of the formula C n H 2n . Chemi- cally, paraffin is extremely stable, and is not attacked by fuming nitric acid. Substitution products are formed when chbrine acts upon paraffin in a molten state. OLEF1NES. B. Unsaturated Hydrocarbons. 1. C n H 2n : defines, Alkylens, Alkenes. 2. C n H 2n _ 2 : Acetylene Series. 3. CnH2n _ 2 = Diolefine Series. 4. C n H 2n _ 4 : Olefinacetylene Series. 5. C n H 2n _ 6 : Diacetylene Series. i. OLEFINES or ALKYLENS. C n H 2n . The hydrocarbons of this series contain two hydrogen atoms less than the limit hydrocarbons. All contain two adjacent carbon atoms united doubly to each other, or, as commonly expressed, they contain a double carbon linkage. The defines readily add two univalent atoms or radicals ; the double carbon union is then severed. Paraf- fins or their derivatives result. The names of the defines are derived from the names of the alcohols containing a like carbon content, with the addition of the suffix "ene": ethylene from ethyl, propylene from propyl, and finally for the series we have the name: alkylens. In the " Geneva* names " the yl oi the alcohol radicals is replaced by " ene ": [ethene] from ethyl, [propene] from propyl, and for the series : alkenes. In long series the position of the double union is indicated by an added number (p. 80). Methylene, =:CH 2 , the hydrogen compound corresponding to CO, has thus far resisted isolation as completely as CH 3 . Two =CH 2 groups invariably unite to ethylene the first member of the series. Beginning with the second member of the series we find, as we advance, that the defines have isomerides in the ring-shaped hydrocarbons the cycloparaffins or cyclic limit hydrocarbons : /~CH 2 The three butylenes have an isomeride in tetramethylene CH 2 .CH 2 Cyclobutane CH 2 .CH 2 The five amylenes " " " " pentamethylene 2 2 \rw Cyclopentane CH 2 .CH 2 ^ The hexylenes are isomeric with hexamethylene CH 2 -CH 2 -CH 2 [Cyclohexane] hexahydrobenzene CH 2 -CH 2 -CH 2 The heptylenes are isomeric with suberene heptamethylene CH 2 .CH 2 .CH 2 [Cycloheptane] CH 2 . CH.-C The cycloparaffins are more closely allied, in chemical character, to the paraffins than to their isomeric defines, as they only contain singly linked carbon atoms. They lack in additive power, as the addition of hydrogen could only result in a rupture of the ring. In their derivatives, the cycloparaffins form the transition from fatty bodies to the aromatic compounds. They will not be considered in the discussion of the olefines. Olefine isomerides appear first with butylene. Three modifications are possible and are also known : (i) CH 3 -CH 2 CH=CH 2 (2) CH 3 CH = CH CH 3 (3) CH 2 =C(CH 3 ) 2 Butylene [Butene i]. Pseudobutylene [Butene 2]. Isobutylene [Methyl Propene]. Five olefines of the formula C 5 H 10 are possible, etc. Ethylene is the type of olefines. It will now receive attention. 8 90 ORGANIC CHEMISTRY. ' Ethylene, CH 2 = CH 2 \_Ethene\, Elayl; called oil-forming gas because, by the action of chlorine, it yields an oily compound, ethylene chloride (see this). This property has given the name to this homol- ogous series. Ethylene is formed in the dry distillation of many organic bodies, and is, therefore, present in illuminating gas (4 to 5 per cent.). Methods of Formation. (i) By heating methylene iodide, CH 2 I 2 , with metallic copper to 100 in a sealed tube (Butlerow) : CH 2 (2) By the action of metallic sodium upon ethylidene chloride (Tollens) and ethylene chloride, as well as from zinc and ethylene bromide : CHCL CH 2 C1 CH 2 CH 2 Br CH 2 or | +2Na=|| +2NaCl; I +Zn=|| + ZnBr 2 . CH 3 CH 2 C1 CH 2 CH 2 Br CH 2 (3) By the action of zinc and ammonia upon copper acetylide : CH CH 2 (4) When alcoholic potash acts upon ethyl bromide : CH 2 Br CH 2 I 4- KOH = || -f KBr -f H 2 O. CH 3 CH 2 (5) Upon heating ethyl sulphuric acid (see below). This is the method usually pursued in the laboratory for the preparation of ethy- lene (A. 192, 244) : (6) Electrolyze a concentrated solution of potassium succinate (see ethane) (Kekule): CH 2 ;CO 2 K HOiH CH 2 H | | + j = jl + 2C0 2 + 2KOH + | . CH 2 ;C0 2 K HO;H CH 2 H Ethylene is a colorless gas, with a peculiar, sweetish odor. Water dissolves but small quantities of it, while alcohol and ether absorb about 2 volumes. It is liquefied at o, and a pressure of 42 atmos- pheres. Its critical temperature is 13, while its critical pressure ex- ceeds 60 atmospheres. It melts at 169, and at ordinary pressure boils at 105, and is suitable for the production of very low tern- OLEFINES. yi peratures. It burns with a bright, luminous flame, decomposing into methane and acetylene (B. 27, R. 459). In chlorine gas the flame is very smoky ; a mixture of ethylene and chlorine burns away slowly when ignited. It forms a very explosive mixture with oxygen (3 volumes). (1) Aided by platinum black it will combine with hydrogen at ordinary temperatures, yielding C 2 H 6 (B. 7, 354). (2) It is absorbed by concentrated hydrobromic and hydriodic acids at 100, with the production of C 2 H 5 Br and C 2 H 5 I : CH 2 CH 3 CH 2 CHJ II +H,= | ; || +HI= \ . CH 2 CH 3 CH 2 CH 3 (3) It combines with sulphuric acid at 160174, forming ethyl sul- phuric acid ; and with sulphuric anhydride it yields carbyl sulphate: CH 2 OH O.C 2 H 5 CH 2 || +S0 2 < = S0 2 < ; (I +2S0 3 CH 2 OH OH CH 2 (4) It unites readily with chlorine and bromine, as well as with alcoholic iodine, and the two modifications of iodine chloride : CH 2 CH 2 Br CH 2 CH 2 C1 II + Br 2 = T ; II + C1I =I ' CH 2 CH 2 Br CH 2 CII 2 I (5) It forms the monochlorhydrin of glycol by its union with hypo- chlorous acid. (6) Ethylene glycol itself, however, is produced by carefully oxi- dizing ethylene with dilute potassium permanganate, which acts as if hydrogen peroxide added itself to the ethylene : CH 2 CH 2 C1 CH 2 OH CH 2 OH || +C10H= f ; . || + | =| CH 2 CH 2 OH CH 2 OH CH,OH Ethylene Homologues. Higher olefines are found in the tar from bituminous shales (B. 28, 496). Just as ethyl alcohol is the most suitable substance for the preparation of ethylene, so are its homologues the best starting-out material for the production of the homologues of ethylene. Methods of Formation. (i) The halogen derivatives, readily formed from the alcohols, are digested with alcoholic sodium or potassium hydroxide. In this reaction the haloid (especially the iodides) derivatives corresponding to the secondary and tertiary alcohols break up very readily. Propylene has been obtained from isopropyl iodide', a-butylene from the iodide of normal butyl alcohol, fi-biitylene from secondary butyl iodide, and isobiitylene from the iodide of tertiary butyl alcohol. Many others have been prepared in the same way. Heating with lead oxide effects the same result (B. n, 414). Tertiary iodides yield olefines when treated with ammonia. 92 ORGANIC CHEMISTRY. (2) Distil the monohydric alcohols, C n H 2n+1 OH, with dehydrating agents, e.g., sulphuric acid, chloride of zinc, and phosphorus or boron trioxide. These remove one molecule of water. Isomeric and polymeric forms are produced along with the normal defines. The secondary and tertiary alcohols decompose with special readiness. The higher alcohols, not volatile without decomposition, suffer the above change when heat is applied to them ; thus cetene, C 16 H 32 , is formed on distilling cetyl alcohol, C 16 H 3*- When sulphuric acid acts upon the alcohols, acid esters of sulphuric acid (the so- called acid ethereal salts see these) appear as intermediate products. When heated these break down into sulphuric acid and C n H 2n hydrocarbons (compare ethylene). The higher defines may be obtained from the corresponding alcohols by distilling the esters they form, with the fatty acids. The products, are an olefine aad an acid (B. 16, 3018) : C 16 H O.O.C 12 H 25 = C 16 H 31 O.OH + C 12 H 24 . Dodecyl Ether of Palmitic Acid. Dodecylene. Palmitic Acid. (3) By the action of metals upon the halogen addition products of the olefines (see ethylene). (4) Electrolyze the potassium salts of saturated dicarboxylic acids (see ethylene). (5) When zinc alkylens act upon brom-olefines, e.g., CH 2 CHBr, which with zinc yields a-butylene or ethyl ethylene. (6) Olefines have also been obtained by the reaction of Wiirtz (p. 84). (7) The formation of higher alkylens in the action of lower mem- bers with tertiary alcohols or alkyl-iodides is noteworthy. Thus, from tertiary butyl alcohol and isobutylene, with the assistance of zinc chlo- ride or sulphuric acid, we get isodibutylene (A. 189, 65 ; B. 27, R. 626): (CH 3 ) 3 C.OH -f CH 2 : C(CH 3 ) 2 = (CH 3 ) 3 C.CH : C(CH 3 ) 2 -f H 2 O. Isodibutylene. The action of the ZnCl 2 is due to the formation of addition products, 2CHCI 3 -> MJ . (4) Formerly acetylene was always made from ethylene bromide by the action of alcoholic caustic potash (A. 191, 268). At first the ethy- lene bromide loses a molecule of hydrogen bromide and becomes mono- brom-ethylene or vinyl bromide, which in turn loses a molecule of hydrogen bromide with the production of acetylene : CH 2 Br CHBr I +KOH=|| CH 2 Br CH 2 CHBr CH II -fKOH=||| -f KBr + H.p. CH 2 CH As ethylene is invariably obtained from ethyl alcohol and sulphuric acid, this method allies acetylene genetically with ethyl alcohol. 96 ORGANIC CHEMISTRY. (5) Acetylene is further produced by the electrolysis of the alkali salts of the two isomeric dicarboxylic acids maleic and fumaric (Kekule, A. 131, 85) : CH;CO 2 K HOiH CH H II ! CHiCO. + j = HI + 2C0 2 + 2KOH + | (p. 76). K HOjH CH H (6) It is worthy of note that potassium acetylene-monocarboxylate and silver acetylene-dicarboxylate are readily converted, when warmed with water, into car- bon dioxide and acetylene, also silver acctylide (A. 272, 139). The stability of the dicarboxylic acids is very much influenced by the manner of union of the carbon atoms, to which the carboxyl groups are attached. C 4 4 Ag, = C 2 Ag 2 + 2C0 2 . Acetylene is further formed when many carbon compounds, like alcohol, ether, marsh gas, methylene, etc., are exposed to intense heat (their vapors conducted through tubes heated to redness). Hence it is present in small amount in illuminating gas, to which it imparts a peculiar odor. Properties. Pure acetylene is a gas of ethereal, agreeable odor, and may be liquefied at -j-i and under a pressure of 48 atmospheres. It solidifies when rapidly vaporized and then melts at 81. It is slightly soluble in water; more readily in alcohol and ether. It burns with a very smoky flame and with air (9 vols.), but especially with oxygen (2*^ vols.), forms an exceedingly explosive mixture. Changes. Nascent hydrogen converts acetylene into C 2 H 4 and C 2 H 6 . Ordinary hydrogen (2 vols.) and acetylene (i vol.) passed over platinum black form C 2 H 6 . (B. 7, 352). Acetylene combines with C1H and HI, forming CH 3 CHC1 2 and CH 3 CHI 2 . Acetylene reacts very energetically with chlorine gas. It forms a crystalline compound with SbCl 5 , but heat changes this to dichlor-ethylene, CHC1 : CHC1 and SbCl 3 . With bromine it forms C 2 H 2 Br 2 and C 2 H 2 Br 4 (A. 221, 138). In contact with HgBr 2 and other mercury salts acetylene unites with water to yield aldehyde, which is also produced when acetylene is heated with water to 325 (B. 28, R. 174). In contact with caustic potash and air it changes in diffused sunlight to acetic acid. Acetylene polymerizes at a red heat. Three molecules unite to one molecule of benzene, C 6 H 6 . This is one of the most striking transi- tions from the aliphatic to the aromatic series and is, at the same time, a synthesis of the parent hydrocarbon of aromatic substances (Ber- thelot). This conversion will take place at the ordinary temperature if acetylene be passed over pyrophoric iron, nickel, cobalt, or platinum sponge (B. 29, R. 540). Metallic Derivatives of Acetylene. The two hydrogen atoms of acetylene can be replaced by metals. The alkali and alkaline earth acetylides are stable even in the heat, but are decomposed by water ACETYLENES. 97 with the liberation of acetylene. Copper and silver acetylides when dry are exceedingly explosive. They are stable in the presence of water. Acids evolve pure acetylene from them. Sodium acetylides, CH == CNa and CNa = CNa. These are produced when sodium is heated in acetylene gas. Calcium acetylide or calcium carbide, C 2 Ca, is formed when calcium oxide is reduced by carbon at a red heat (Wohler, 1862), and when a mixture of calcium oxide and sugar carbon is heated in electric furnaces to 3500 (Moissan, B. 27, R. 238). It is a homogeneous, black fusion with a crystal- line fracture. Drop fragments of calcium carbide into a tall glass cylinder filled with saturated chlorine water, when the liberated acetylene will combine with the chlorine with the production of flame. Gas-bubbles, giving out light, rise in the liquid and when they reach the surface burn there with a smoky flame. Lithium carbide, C 2 Li 2 (B. 29, R.2io). Silver acetylide, C 2 Ag 2 , a white precipitate, and copper acetylide, C 2 Cu 2 (B. 25, 1097; 26, R. 608; 27, R. 466), a red precipitate, are formed on conducting acetylene into ammoniacal silver or cuprous solutions. The dry salts explode violently when they are heated. The silver salt even does this when gentry rubbed with a glass rod. In a solution of silver nitrate acetylene precipitates the compound HC = CAg.NO 3 Ag (B. 28, 2108). Pure acetylene is set free by acids from these metallic compounds. The copper salt serves for the detection of acetylene in a mix- ture of gases. Mercury acetylide, C 2 Hg, is thrown out as a white precipitate from alkaline, solutions of mercuric oxide. It explodes violently when heated rapidly. Acetylene mercuric chloride, C 2 (HgCl) 2 , is precipitated on passing acetylene through solutions of corrosive sublimate. It is not explosive (B. 27, R. 83, 466). Acetylene Homologues. The diolefines are isomeric with the homologues of acetylene. They contain a like number of carbon atoms, e.g., allene, CH 2 = C = CH 2 , is isomeric with methyl acetylene, CH 3 . C = CH, allylene, and divinyl, CH 2 : CH . CH : CH 2 , with dimethyl acetylene, CH 3 . C j C . CH 3 , crotonylene. Its higher homologues, just like acetylene, are mostly prepared from the mono-halogen and dihalogen substitution products of the defines, the define dibromides, by the action of alcoholic potash, e. g., from CH 3 CC1=:CH 2 : allylene; from CH 3 . CHBr . CHBr . CH 3 : crotonylene, CH 3 C = C . CH 3 . In this manner a host of higher acetylene homo- logues have been prepared from the dibromides of the higher olefines (B. 25, 2243)- When heated to a high temperature with alcoholic potash the acetylene formed frequently sustains a transposition; thus, ethyl acetylene, C 2 H 5 .C =. CH, jields dimethyl acetylene, CH 3 .C EE C.CH 3 , and propyl acetylene, C 3 H 7 .C = CH, furnishes ethyl methyl acetylene, C 2 H 5 . C = C . CH 3 , etc. (B. 20, R. 781). Sym- metrically constituted bodies are formed from unsymmetrical compounds. The reverse transposition sometimes occurs on heating with metallic sodium : ethyl methyl acetylene passes into propyl acetylene, and dimethyl allene, (CH 3 ) a C = C = CH 2 , yields isopropyl acetylene, etc. (B. 21, R. 177). Acetylenes also arise in the electrolysis of unsaturated dibasic acids. Thus allyl- ene is formed in the electrolysis of the alkali salts of mesaconic and citraconic acids. Acetylene and its homologues unite with hydrogen to form olefines, which in turn pass into paraffins. By adding the haloid acids or the halogens the mono- and di-haloid olefines are formed. The further 9 98 ORGANIC CHEMISTRY. addition of haloid acids and halogens to these yields di-, tri-, and tetra-halogen substitution products of the paraffins. Hypochlorous acid converts the alkines into dichlor-acetones, e. g.> a-dichlor- propyl methyl ketone CH 3 CH 2 CC1 2 .CO.CH 3 (B. 28, R. 781) and water are obtained from methyl ethyl acetylene and the acid : C 2 H 5 C = C . CH 3 + 2C1OH. Ketones are formed when the alkyl acetylenes are heated with water to 325 (B. 27, R. 750; 28, R. 173). A characteristic of all mono-alkyl-acetylenes, as well as of acetylene itself, is their power to yield solid crystalline compounds by the action of ammoniacal solutions of silver and cuprous salts. Hydrochloric acid will again liberate the acetylenes from these salts. The behavior affords a very convenient method for separating the acetylenes from other gases, as well as for obtaining them in a pure condition. The acetylenes are absorbed by concentrated sulphuric acid ; some even polymerize to aromatic derivatives. In the presence of HgBr 2 and other salts of mercury, the acetylenes can unite with water. In this way we get from acetylene, aldehyde, C 2 H 4 O, from allylene, C 3 H 4 , acetone, C 3 H 6 O, from valerylene, C 5 H 8 , a ketone, C 5 H 10 O (B. 14, 1540, and 17, 28). Very often moderately dilute sulphuric acid will act in the same way (see Allylene). The boiling points of some of the acetylenes are as follows : B. P. Allylene, Methyl-acetylene [Propine] CH 3 C = CH Gas Crotonylene, Dimethyl Acetylene [2-Butine] CH 3 C=:CCH 3 27-28 Ethyl Acetylene [3-Butine] C 2 H 5 C = CH 18 Methyl Ethyl Acetylene |>Pentine] C 2 H 5 C = CCH, 55~56 Norm. Propyl Acetylene [4-Pentine] n-C 3 H 7 C = CH 48-49 Isopropyl Acetylene [3-Methyl- 1- Butine] (CH 3 ) 2 CH . C = CH 28-29 Allylene and crotonylene deserve consideration, because when brought in contact with concentrated sulphuric acid they pass into symmetric trimethyl benzene and hexamethyl benzene. 3CH 3 C = CH > C 6 H 3 [I,3,5](CH 3 ) 3 Mesitylene. 3CH 3 C = CCH 8 >- C 6 (CH 3 ) 6 Hexamethyl Benzene. 3. DIOLEFINES, C n H 2n _ 2 . The diolefines are not capable of forming silver and copper com- pounds. They do give precipitates with mercuric sulphate and chlo- ride in aqueous solution (B. 21, R. 185, 717; 24, 1692). The " Geneva names" for the diolefines are derived by inserting a "di," for the number of double linkages, before the final syllable "ene" e. g., [propadiene] for symmetric allylene. The hydrocarbons of this class are numerous. Some of them are worthy of note because of their genetic relations. They are : OLEFINACETYLEN ES. 99 1. Allene, sym. allylene [Propadiene] CH 2 _ C=CH 2 Gas 2. Divinyl, Erythrene [i, 3-Butadiene]CH 2 CH CH=CH 2 Gas Pyrrolylene 3. Piperylene [i, 4-Pentadiene] CH 2 =CH CH 2 CH^rCH, 42 4. Isoprene CH 2 =CH C(CH,)=CH. (?) *c<> 5. Diallyl [i, 5-Hexadiene] CH 2 =CH-CH 2 CH 2 CH=CH 9 597 6. Conylene [i, 4-Octadiene] CH 2 ^CH CH 2 CH=CH.CH 2 .CH 2 .CHg 126. Symmetric allylene has been obtained by the electrolysis of potassium itaconate (P- 76). Divinyl, Erythrene, or Pyrrolylene is found in compressed illuminating gas. and serves as the starting-out material for the synthesis of erythrol, which yields it on boiling with formic acid. It is called pyrrolylene because it is formed in the breaking down of pyrrolidine or tetra-hydropyrrol (see this) (B. 19, 569). - Piperylene and Conylene are formed in the same manner from piperidine (see this) and coniine (see this) (B. 14, 665, 710). Isoprene, a distillation product of caoutchouc, is closely related to the terpenes. It is called a hemiterpene, and by spontaneous polymerization passes into dipentene or cinene, and then back into caoutchouc (B. 25, R. 644). Diallyl is formed from allyl iodide by means of sodium (see hexyl-erythrol). 4. OLEFINACETYLENES. By this name are understood the hydrocarbons containing both doubly and trebly linked pairs of carbon atoms in their molecules. Many of them are known, but none deserve special consideration. 5. DIACETYLENES, C n H 2n _ 6 . Diacetylene, HC C.C CH, is formed from diacetylene dicarbonic acid. It is a gas that yields a yellow precipitate with an ammoniacal silver solution. The two hydrocarbons, dipropargyl and dimethyl-di-acetylene, are isomeric with benzene. Dipropargyl, CH j C. CH 2 . CH 2 . C CH, is formed on warming solid crystal- line diallyltetrabromide, C 6 H 10 Br 4 , with KOH. It is a very mobile liquid, of penetrat- ing odor, and boiling at 85. It forms copper and silver derivatives. If dipropargyl be allowed to stand, it becomes resinous. - Dimethyl Di-acetylene, CH 3 .CEEC.CEEC.CH ? , has been obtained from the copper derivative of allylene. It melts at 64 and boils at 130 (B. 20, R. $64). HALOGEN DERIVATIVES OF THE HYDROCARBONS. The halogen substitution products result from the replacement of hydrogen in the hydrocarbons by the halogens. In the discussion of the methods of formation and the transpositions of the saturated and unsaturated aliphatic hydrocarbons, their haloid derivatives were con- stantly encountered. We have also learned the methods of producing these alkylogens, proceeding from the hydrocarbons. They are : (i) Formation by the direct substitution of the limit hydrocarbons. It was emphasized in the case of methane (p. 82) and ethane (p. 83) that these hydrocarbons, usually so very stable, were attacked by chlorine. A molecule of hydrogen chloride is produced for every 100 ORGANIC CHEMISTRY. hydrogen atom replaced by chlorine, until the entire hydrogen con- tent is substituted. Methane, CH 4 , yields tetra- or perchlormethane, CC1 4 , while ethane gives hexa- or perchlorethane, QC1 6 . The action of chlorine is accelerated by, and very often also dependent upon, direct sunlight or the presence of small quantities of iodine. It is the IC1 3 , which arises in the latter case, that facilitates the reaction. SbCl 6 also plays the role of a chlorine carrier, since upon heating it yields SbCl 3 and 2C1. In very energetic chlorination the carbon chain is ruptured (B. 8, 1296; 10, 801). The final products are CC1 4 and hexa- or perchlorbenzene, C 6 C1 6 , with perchlor- ethane, C 2 C1 6 , and perchlormesole, C 4 C1 6 , as intermediate products (B. 24, ion). Heat hastens the action of bromine. Its action is also accelerated by sunlight or with AlBr 3 as a carrier. Iron is an excellent carrier of chlorine, bromine, and iodine. Its action seems to be due to the formation and decomposition of compounds with ferric halides (A. 225, 196; 231, 158). When iron is used as a bromine carrier every normal hydro- carbon passes into that bromide, which contains just as many bromine atoms as it has carbon atoms (B. 26, 2436); a bromine atom attaches itself to each carbon atom. Usually iodine does not replace well, inasmuch as the final iodine products sustain reduction through the hydriodic acid formed simultaneously with them : In the presence of substances (like HIO 3 and HgO) capable of uniting or decom- posing HI, iodine frequently effects substitution : 5 C 3 H 8 + 2I 2 + I0 3 H = 5 C 3 H 7 I + 3 H 2 2 C 3 H 8 + 2I 2 + HgO = 2C 3 H 7 I + H 2 + HgI 2 . In direct substitution a mixture of mono- and poly-substitution products generally results, and these are separated by fractional distillation or crystallization. (2) The unsaturated aliphatic hydrocarbons, the olefines (p. 93) and acetylenes (p. 98) add hydrochloric, hydrobromic, and especially hydriodic acids. The haloid acid is dissolved in glacial acetic acid (B. n, 1221), or it is applied in concentrated aqueous solution. (3) The free halogens are absorbed by the unsaturated hydrocarbons with more avidity than the haloid acids (p. 89). Two additional reactions (already indicated in the preceding re- marks as existing) proceed from oxygen-containing aliphatic deriva- tives to halogen substitution products : (4) Replacement of the hydroxyl groups of the alcohols by fluorine, chlorine, bromine, or iodine by means of the haloid acids or by means of the phosphorus halides (p. 116). (5) By the action of phosphorus pentachloride and phosphorus chlorbromide, or phosphorus pentabromide upon aldehydes and ketones. These last methods of formation will be more thoroughly discussed under the individual groups of halogen substitution products. Transpositions of the Halogen Derivatives. The iodine derivatives of the halogen substitution products are the most unstable. In the light they rapidly acquire a red color, with the separation of ALKYL HAL1DES. IOI iodine. The chlorides and bromides, rich in hydrogen, burn with a green-edged flame (p. 24). (1) Nascent hydrogen (zinc and hydrochloric acid or glacial acetic acid, sodium amalgam and water) can reconvert all the halogen deriv- atives, by successive removal of the halogen atoms, into the corre- sponding hydrocarbons (p. 83) : CHC1, + 3 H 2 = CH 4 + 3 HC1. This change is called a retrogressive substitution. (2) Alcoholic sodium and potassium hydroxides occasion the split- ting off of an halogen hydride, and the production of unsaturated compounds (p. 91) : CH 3 . CH 2 . CH 2 Br -f KOH = CH 8 . CH : CH 2 + KBr + H 2 O. Propyl Bromide. Propylene. In this reaction the halogen attracts to itself the hydrogen of the least hydrogen- ized adjacent carbon atom (compare p. 93). Such a splitting sometimes occurs on application of heat. A. HALOGEN PARAFFINS. I. MONOHALOGEN PARAFFINS, ALKYLOGENS, ALKYL HALIDES, C n H 2n + X X. These are genetically connected by reactions to the alcohols, which are almost always employed in their preparation. It is impossible to obtain mono-iodo-paraffins by direct substitution. On comparing the formulas of the alkylogens with those of the halogen hydrides, HF/ HC1 HBr HI H.OH C 2 H 5 F1' C 2 H 3 C1 C 2 H 5 Br C 2 H 5 I C 2 H 5 .OH it will be seen that they can be regarded as haloid acids, in which the hydrogen atoms have been replaced by hydrocarbon residues. As the latter, together with the water residue, constitute the monohydric (mon- acid) alcohols, they are called alcohol radicals or alkyls. Acids, the hydrogen of which is replaceable by metals, yield acid esters when alcohol radicals are substituted for that hydrogen. The monohalogen alkyls are therefore discussed as haloid esters, at the head of the acid esters of the monacid alcohols. 2. DIHALOGEN PARAFFINS, C n H 2n X 2> (0) Dihalogen paraffins, where two halogen atoms are attached to two different carbon atoms, may be viewed as the haloid esters of diacid paraffin alcohols or glycols. They can be derived from these and will be considered together with them : 102 ORGANIC CHEMISTRY. CH 2 C1 CH 2 .OH ,CILBr ,CH 2 .OH I I CH,( CM/ CH,C1 CH 2 .OH X CH 2 Br Ethylene Chloride. Ethylene Glycol. Trimethylene Trimethylene Bromide. Glycol. (/) Dihalogen paraffins, the two halogen atoms of which are attached to the same carbon atom, may be termed aldehyde- halides, if the carbon atom is terminal, and ketone-halides, when the carbon atom occupies an intermediate position. Indeed, these compounds can be obtained from the aldehydes and ketones by means of phosphorus halides. They will, therefore, be discussed after the aldehydes and the ketones : CH 3 CHO ,CH 3 I CC1 / CO CH 3 3 3 Ethylidene Chloride Acetaldehyde. Acetone Chloride Acetone. Aldehyde Chloride. |3-Dichlor-propane. It must be remarked here that the unsymmetric ethane dihalides e.g., CH 3 . CHC1 2 , ethylidene chloride have lower boiling points and lower specific gravities than the corresponding symmetric iso- merides, e.g., ethylene chloride, CH 2 C1 . CH a Cl. 3. PARAFFIN POLYHALIDES. The paraffin polyhalides, containing but one halogen atom to each carbon atom, will be discussed after the corresponding polyacid paraffin alcohols. The simplest and most important representatives of the paraffin- trihalides, in which three halogen atoms are attached to the same carbon atom, are the methane trihalides : CHC1 3 CHBr 3 CHI 3 Chloroform. Bromoform. lodoform. They are so intimately related to formic acid and its derivatives that they will be considered after this acid. The most important paraffin tetrahalides are the methane tetrahalides. They bear the same relation to carbonic acid that the methane tri- halides sustain to formic acid. They will, therefore, be treated after carbonic acid : CF1 4 CC1 4 CBr 4 CI 4 Methane Methane Methane Methane Tetrafluoride. Tetrachloride. Tetrabromide. Tetraiodide. These compounds are also called methane perhalides, to indicate that all the hydrogen in them is completely replaced by halogens. PARAFFIN POLYHALIDES. Polyhalide Ethanes. The following table contains the boiling points of the known polychlor- and polybrom-ethanes : Name. Formula. M. P. B. P. Formula. M. P. B. P. Vinyl Trichloride /3-Trichlor-ethane CHC1 2 CH 2 C1 II 4 CHBr 2 CH 2 Br 187-188 Ethenyl Trichloride CCL a-Trichlor-ethane h^ 74-5 Methyl Chloroform CH 3 Acetylene Tetrachloride CHC1 2 CHBr 2 102 Symmetrical CHC1 2 "~ 147 CHBr 2 (12 mm.) Acetylidene Tetrachloride Unsymmetrical CC1 3 CH 2 C1 129-130 CBr 3 CH 2 Br 105 (13.5 mm.) CCL CBr, Pentachlor-ethane CHC1 2 159 CHBr 2 54 decomposes Perchlor-ethane CC1 3 CC1 3 I8 7 sublimes CBr 3 CBr 3 decomposes at 200-210 without de- composition. For the relations existing between the boiling points and specific volumes of the halogen substitution products of the ethanes, see B. 15, 2559. As to the refractive power of the brominated ethanes, see Z. phys. Ch. 2, 236. The polychlor- and polybrom-ethanes have few genetic relationships with the oxygen compounds corresponding to them. The methods of formation and the transpositions of the polysubstituted ethanes are most intimately related to the methods of formation and the trans- positions of the halogen substitution products of the ethylenes and acetylenes, a tabular view of which will be given in the following section. They will, therefore, precede the discussion of the latter. It may be merely mentioned here that by the action of chlorine upon ethyl chloride and ethylidene chloride in sunlight methyl-chloroform or a-trichlor-ethane, CH 3 CC1 3 , will be produced, together with vinyl trichloride, CH 2 C1. CHC1 2 . The further action of chlorine upon the trichlorethanes produces: CH 2 C1 . CC1 3 , CHC1 2 .CC1 3 , perchlor-ethane, CC1 3 . CC1 3 . CHC1 2 . CHC1 2 is formed from acetylene dichloride and chlorine, as well as from dichloraldehyde by means of phosphorus pentachloride (B. 15, 2563). Only methyl chloroform, CH 3 . CC1 3 , related to acetic acid the same as chloroform is to formic acid, will be further described, together with the chlorides of the fatty acids. Perchlor-ethane, C 2 C1 6 , is a crystalline mass, with a camphor-like odor. Its specific gravity equals 2.01. It melts at 187-188 (corr.). It sublimes at the ordi- nary pressure, as its critical pressure lies below 760 mm. It boils at 185.5 under a pressure of 776.7 mm. When its vapors are conducted through a tube heated to 104 ORGANIC CHEMISTRY. redness it breaks down into C1 2 and per chlor ethylene. It yields the latter compound when it is treated with potassium sulphide. a- Tribromethane, CH 3 . CBr 3 , has not yet been prepared. Acetylene Tetrabromide, CHBr 2 . CHEr 2 , is obtained from acetylene and bromine. Zinc dust and alcohol convert it into acetylene dibromide (A. 221, 141), while benzene and A1C1 3 change it into anthracene (see this.) Perbromethane, C 2 Br 6 , is a colorless, crystalline compound, dissolving with diffi- culty in alcohol and ether. It breaks down at 200 into bromine and perbromethylene , Five structural cases are possible for trisubstituted propane. The most important of these derivatives have the structure CH 2 X.CHX.CH. 2 X, corresponding to glycerol, CH 2 (OH) . CH(OH) . CH 2 (OH). They will be discussed after the latter. Mixed Halogen Substitution Products of the Paraffins. There are numerous paraffins containing different halogens side by side in the same molecule. B. HALOGEN DERIVATIVES OF THE OLEFINES. As a general thing, the halogen substitution products of the unsat- urated hydrocarbons cannot be prepared by direct action of the halo- gens, since addition products are apt to result (p. 89). They are produced, however, by the moderated action of alcoholic potash, or Ag 2 O, upon the disubstituted hydrocarbons C n H 2n X 2 . This re- action occurs very readily if we employ the addition products of the defines : C 2 H 4 C1 2 + KOH = C 2 H 3 C1 + KC1 + H 2 O. Ethylene Monochlor- Chloride. ethylene. When the alcoholic potash acts very energetically, the hydrocarbons of the acetylene series are formed (p. 95). Being unsaturated com- pounds they unite directly with the halogens, and also, the hydrides of the latter : CH 2 CH 2 Br II + Br 2 = | CHBr CHBr, These reactions indicate that ethylene is the starting- out substance for the prepa- ration of nearly all the halogen substitution products of the ethanes and ethylenes, as well as for the preparation of acetylene. The following diagram represents how, by the addition of bromine and the split- ting-off of hydrogen bromide, the bromine substitution derivatives of the ethanes are connected with ethylene, with the ethylene bromine derivatives, and with acety- lene (A. 221, 156) : HALOGEN DERIVATIVES OF THE OLEFINES. I0 5 CH 2 =CH 2 HBr CH=CBr CBr 3 .CBr s . Vinyl Chloride, CH 2 = CHC1, and Vinyl Bromide, CH, = CHBr, are obtained from ethylene chloride and ethylene bromide by the action of alcoholic potash, which, by continued action upon them, produces acetylene. The group CH 2 = CH is called vinyl. The boiling points of the chlorinated and brominated cthylenes are given in the following table : Formula. B. P. Formula. B. P. Vinyl Chloride, Monochlor- ethylene, CH 2 = CHC1 1 8 CH 2 = CHBr + 16 Acetylene Bichloride, sym. Dichlorethylene, .... CHC1 = CHC1 - +55 CHBr = CHBr 110 Acetylidene Dichloride, unsym. Dichlorethylene, Tricolor- ethylene, .... CH 2 =CC1 2 CHC1 = CC1 2 +37 88 CH 2 = CBr 2 CHBr=CBr 2 9i 164 Tetrachlor ethylene, Per- M. P. chlor-ethylene, . .' . . CC1 2 = CC1 2 121 CBr 2 = CBr 2 53 Tetra-iodo ethylene (B. 26, R. 289; 29,1411), CI 2 = CI 2 187 Consult A. 221, 156, for the boiling point relations of the'brom-ethanes^and brom- ethylenes. The unsymmetrical compounds, CH 2 = CHC1, CH 2 = CHBr, CH 2 = CC1 2 and CH 2 =CBr 2 , polymerize quite easily (B. 12, 2076). CH 2 = CBr 2 and CHBr=CBr 2 yield CH 2 Br.COBr, brom-acetyl bromide, and CHBr 2 COBr, dibrom-acetyl bro- mide (B. 16, 2919 ; 21, 3356) with oxygen. Ozonized air converts perchlorethylene into phosgene, COC1 2 , and trichloracetyl chloride (B. 27, R. 509). Consult A. 235, 150, 299, for the action of A1C1 3 on polybrom-ethanes and ethylenes, in the presence of benzene. See B. 26, R. 18, 19, for the addition of iodine to acetylenes. 106 ORGANIC CHEMISTRY. Three different mono-halogen products are derived from propylene, CH 3 CH- = CH 2 : (i) CH 3 CH = CHX (2) CH 3 CX = CH 2 (3) CH 2 X CH = CH 2 . a-Derivatives. /3-Derivatives. y-Derivatives. (1) The a-derivatives are obtained from the propylidene compounds, CH 3 . CH 2 .CHX 2 (from propyl aldehyde), when the latter are heated with alcoholic potas- sium hydroxide. (2) The /3-derivatives, CH 3 .CX:CH 2 , are prepared in pure condition from the halogen compounds, CH 3 .CX 2 .CH 3 (p. 102), derived from acetone. (3) The ^-derivatives of propylene, CH 2 X CH = CH 2 , are des- ignated Allyl haloids, because they correspond to ally! alcohol, CH 2 :CH.CH 2 OH. They will be described after the alkylogens. C. HALOGEN ACETYLENES. Acetylene Chloride, C 2 HC1, has been obtained from dichlor-acrylic acid, CC1 2 = CH.CO 2 H, by the action of baryta. It is an explosive gas (A. 203, 88 ; B. 23, 3783). Acetylene Bromide, C 2 HBr, obtained from the dibromide by means of alcoholic potash, is a gas, inflaming in air contact. Acetyhne Iodide, C 2 HI, is formed on boiling potassium iodopropargylate with water (B. 18, 2274). Acetylene Di iodide, C 2 T 2 , is produced when iodine acts upon silver acetylide. It melts with decomposition at 78. It changes largely to ethylene tetraiodide (B. 29, 1411) in the light or when it is heated. The halogen acetylene derivatives polymerize more easily than acetylene itself. The products are in part benzene derivatives : monobrom-acetylene yields tribrom- benzene. 3 CH = CBr = C 6 H 3 Br 3 ; 3 CH = CI = C 6 H 3 I 3 ; 3 CI = CI =C 6 I 6 . Tribrom-benzene. Tri-iodo-benzene. Hexa-iodo-benzene. Perchlormesole, C 4 C1 6 = CC1 3 .C = C.CC1 3 (?) or CC1 2 == CC1 CC1 = CC1 2 (?), may be mentioned here. It frequently appears in exhaustive chlorinations. It melts at 39 and boils at 284 (B. 10, 804; compare B. 22, 1269). OXYGEN DERIVATIVES OF THE METHANE HYDROCARBONS. We became acquainted with the simplest linkings of the carbon atoms in studying the aliphatic hydrocarbons and their halogen substitution products. The derivatives next in order are the oxygen compounds. They furnish further cause for the classification of the carbon com- pounds. We may consider them as formed from the aliphatic hydro- carbons by the substitution of the univalent water residue the hydroxyl group OH, for hydrogen. But one or several hydroxyl groups attach themselves to each carbon atom. In the first instance alcohols result. These are neutral com- pounds, closely related in many respects to water. Alcohols, accord- ing to the number of hydroxyl groups present in them, are classified as mono-, di-, tri-, and poly-hydric, because in the alcohols with one hydroxyl a univalent radical, and in those with two hydroxyls a biva- HALOGEN ACETYLENES. 107 lent radical, etc., is in union with the water residues. Therefore, the simplest monohydric alcohol contains one carbon atom, the simplest dihydric alcohol two carbon atoms, etc., as indicated in the following arrangement : CH 4 CH 3 . OH Methyl Alcohol, the simplest monohydric alcohol. CH :{ CH 2 . OH CH . OH.) They do not furnish corresponding aldehydes and acids. When oxidized they pass into ketones (p. 108) : frw 3 f CH 3 CH 3 ^ 3 yields C 1 CH 3 == >CO SH lo CH s Dimethyl Carbinol. Acetone. When, finally, all three hydrogen atoms in carbinol are replaced by alkyls, we get the tertiary alcohols ', containing the group -jC . OH. MONOHVDRIC ALCOHOLS. Ill In! 3 CI V C j 3 = CHg^C.OH Trimethyl Carbinol. ! ,\,, :? CH,' [ OH The tertiary alcohols decompose when oxidized. The secondary and tertiary alcohols, in distinction from the primary or true alcohols, are designated pseudo-alcohols. The " Geneva names " for the alcohols are derived from the names of the corre- sponding hydrocarbons, with the addition of the final syllable "ol ": CH 3 . OH = [Methanol] ; CH 3 . CH 2 . OH = [Ethanol] ; CH 3 . CH 2 . CH 2 . OH = [l-Propanol] ; CH 3 . CHOH . CH 3 = [2-Propanol]. The parallels in the formulas of the three classes of alcohols and the three classes of amines (see these) are very evident upon studying the following general formulas : R \ R . CH 2 . OH R> CH OH R -7 C OH Primary Alcohols. R/ Secondary Alcohols. R R \ R.NH 2 R> NH R 7 N R Primary Amine. Secondary Amine. Tertiary Amine. The deportment of alcohols on oxidation is of great importance in answering the question as to whether a certain alcohol is primary, sec- ondary, or tertiary in its character. What has already been submitted may be summarized thus: A primary alcohol on oxidation yields an aldehyde, which passes into an acid if the action be continued. This acid contains as many carbon atoms in its molecule as the parent alcohol. Oxidation changes a sec- ondary alcohol \n\.o&ketone, having an equal number of carbon atoms in its molecule. A tertiary alcohol breaks down on oxidation into compounds having a lower carbon content. The basis of the classification of the next section is : The monohydric alcohols and their oxidation products : (la) Primary- Alcohols (_CH. . OH) (i) Secondary Alcohols ( CH . OH) i (ic) Tertiary Alcohols (=C . OH). O 10 I/O t (2) Aldehydes (_cf ). (3) Ketones (=CO) X H / (4) Carboxylic Acids (__C^ ) X)H Four classes of oxygen derivatives must, therefore, be distinguished. The unsaturated derivatives attach themselves to the saturated of each class. 112 ORGANIC CHEMISTRY. Formation of Alcohols. Review of Reactions. They are ob- tained from bodies containing a like number of carbon atoms : (1) By the saponification of acid esters. (2) By the reduction of polyhydric alcohols. (3) By the action of nitrous acid upon amines. (4) By the reduction of their oxidation products. From nucleus-syntheses (p. 85) : (5) By the action of zinc alkyls, or zinc alkyls and alkyl iodides, upon aldehydes, acid chlorides, ketones, formic esters, acetic esters, and chlorinated ethers. (i#) From Haloid Esters or Alkylogens. It was mentioned, in describing the transformations of the alkylogens, that the latter afford a means of passing from the paraffins and olefines to the alcohols (p. 101). As caustic alkali causes the separation of a halogen hydride from the alkylogens, it is possible to exchange hydroxyl for the halogen, espe- cially if this be iodine. This is most easily accomplished by the action of freshly precipitated, moist silver oxide, or by heating with lead oxide and water : C 2 H 5 I + AgOH = C 2 H 5 . OH + Agl. Even water alone causes a partial transposition of the more reactive tertiary alkyl iodides ; whereas the other alkylogens in general when heated for some time with 10-15 volumes of water to 100 are completely converted into alcohols (A. 186, 390). Tertiary alkyl iodides heated to 100 with methyl alcohol pass into methyl alcohols and methyl iodide (A. 220, 158). (i) By the Saponification of their Esters. It is often more practical to first convert the halogen derivatives into acetic acid esters, by heating with silver or potassium acetate : C 2 H 5 Br -f C 2 H 3 O . OK = C 2 H 5 . O . C 2 H 3 O -f KBr, Potassium Acetate. Ethyl Acetic Ester. and then boil these with potassium or sodium hydroxide, and obtain the alcohols : C 2 H 5 . O . C 2 H 3 + KOH = C 2 H 5 . OH + C 2 H 3 O . OK. The second reaction is called saponification, because by means of it the soaps, i. e., the alkali salts of the fatty acids and glycerol (see this), are obtained from the glycerol esters of the fatty acids the fats. (\c) By decomposing the acid esters of sulphuric acid with boiling water : H * = C * H 5- OH + SO * H *- Ethyl Sulphuric Acid. This reaction constitutes the transition from the olefines to the alcohols, as these esters may be easily obtained by directly combining the unsaturated hydrocarbons with sulphuric acid. Many alkylens (likeiso- and pseudo-butylene) dissolve at once in dilute nitric acid, absorb water, and yield alcohols (A. 180, 245). MONOHYDRIC ALCOHOLS. 113 (2) The reduction of polyhydric alcohols by hydriodic acid yields the iodides of secondary alcohols, which are converted by methods la and ib into the alcohols themselves, e. g, : CH 2 OH CH 3 I HI CHOH Glycerol. Isopropyl Isopropyl Iodide. Alcohol. Or, the chlorhydrins of the polyhydric alcohols may be reduced, e, g. : CH 2 C10H CH 2 OH 2H CH 2 OH pTT f'TJ C*\ f*W i^iirt vxXiftV^i Vxil. Ethylene. Ethylene Chlorhydrin. (3) Action of nitrous acid upon the primary amines : C 2 H 5 NH, + NO . OH = C 2 H 5 . OH -f N a + H 2 O. Very often transpositions occur with the higher alkylamines, and instead of the primary alcohols, we obtain secondary alcohols (B. 16, 744). (40) Primary alcohols result from the reduction of aldehydes, acid chlorides, and acid anhydrides : C 2 H 5 . COH -f 2H = CH 3 . CH 2 . CH, . OH (Wiirtz, A. 123, 140). Propyl Aldehyde. CH 3 . COC1 + 4H = CH 3 . CH 2 . OH -f- HC1. Acetyl Chloride. CH 3 ' CO >O + 4H = C 2 H 5 OH + CH 3 COOH (Linnemann, A. 148, 249). Acetic Anhydride. Aldehydes are first formed in the reduction of acid chlorides and anhydrides ; they in turn are reduced to alcohols. The reducing agents are dilute sulphuric acid or acetic acid, together with sodium amalgam, sodium, iron filings, and zinc dust (B. 9, 1312; 16, 1715). This is the last of those reactions by which an alcohol can be converted into an- other, containing an atom more of carbon. The alcohol is changed through the iodide to the cyanide, and the latter to the acid, which, by reduction of its chloride or its aldehyde, yields the new alcohol : CH 3 .OH ^ CH 3 I H2H 3 CN - > CH 8 . COOH > CH S COC The reduction of ketones yields secondary alcohols (Friedel, A. 124, 324), together with pinacones (see these), the di-tertiary dihydric alcohols or glycols : CH 3 CH S CH S CH, CH S CO +'2H=CHOH; 2CO + 2H = HO C C . OH CH 3 CH, CH S CH 8 CH 8 Acetone. Isopropyl Alcohol. Pinacone. 114 ORGANIC CHEMISTRY. Nucleus-synthetic Methods of Formation. (50) Acid Chlorides and Zinc A Iky Is ; Ketones, Zinc Alkyls and Alky - logens. A very remarkable synthetic method, proposed by Butlerow (1864), which led to the discovery of the tertiary alcohols, consists in the action of the zinc compounds of the alkyls upon the chlorides of the acid radicals (Z. f. Ch., 1864, 385 ; 1865, 614). The reaction divides itself into three phases. At first only one molecule of zinc alkyl reacts, and adds itself to the acid chloride as a result of the breaking down of the double linkage between the carbon and oxygen : O fCH 3 (I) CH 3 . Of + Zn(CH 8 ), = CH.C \ O . Zn . CH 3 . X C1 LCI Acetyl Chloride. By decomposing the reaction-product with water, acetone is formed. However, should a second molecule of the zinc alkyl act upon the new compound, further reac- tion will take place on longer standing: iCH 3 ( CH, ri O . Zn . CH 3 + Zn (CH 3 ) 2 = CH 3 . C j O . Zn . CH 3 -f Zn | gj If now water be permitted to take part, a tertiary alcohol will be formed : rCH 3 rCH 3 (3) CH 3 . C 4 O . Zn . CH 3 -f 2H 2 O = CH 3 . C 4 OH -f Zn(OH) 2 -f CH 4 . I CH 3 ( CH 3 If in the second stage the zinc compound of another radical be employed, the latter may be introduced, and in this manner we obtain tertiary alcohols with two or three different alkyls (A. 175, 374, and 188, no, 122). It is remarkable that only zinc methyl and ethyl furnish tertiary alcohols, while zinc propyl affords only those of the secondary type (B. 16, 2284; 24, R. 667). The ketones in general do not react with the zinc alkyls. On the other hand, diethyl-acetone, (C 2 H 5 ) 2 CO, and dipropyl ketone, (C 3 H 7 ) 2 CO, are converted by zinc and methyl (ethyl) iodide into zinc alkyl compounds ; these, under the influence of water, pass into tertiary alcohols (B. 19, 60 ; 21, R. 55). We get unsaturated tertiary alcohols from all the ketones by the action of zinc and allyl iodide (A. 196, 113). When zinc alkyls act upon aldehydes, only one alkyl group enters, and the reaction product of the first stage yields a secondary alcohol when treated with water (A. 213, 369; and B. 14, 2557): CH 3 . CHO Aldehyde. * Methyl-ethyl Carbinol. All aldehydes (even those with unsaturated alkyls, and also furfuran) react in this way but only with zinc methyl and zinc ethyl, while with the higher zinc alkyls the aldehydes suffer 'reduction to their corresponding alcohols (B. 17, R. 318). With zinc methyl chloral yields trichlorisopropyl alcohol, CC1 3 . CH(OH) . CH 3 ; whereas with zinc ethyl it is only reduced to trichlorethyl alcohol (A. 223, 162). (5 r ) J ust as we obtained tertiary alcohols from the acid radicals, so can we derive secondary alcohols from the esters of formic acid. Zinc MONOHYDRIC ALCOHOLS. 115 alkyls arc allowed to react in this case (or, better, alkyl iodides and zinc), and two alkyls are introduced : /O . Zn . CH 3 X . Zn . CH, /OH .C 2 H 5 \O.C 2 H 5 \CH 3 Ethyl Formic Ester. Dimethyl Carbinol. Using some other zinc alkyl in the second stage of the reaction, or by working with a mixture of two alkyl iodides and zinc, two different alkyls may also be introduced here (A. 175, 362, 374). Zinc and allyl iodide (not ethyl-iodide, however) react similarly upon acetic acid esters. Two alkyl groups are introduced and unsaturated tertiary alcohols formed (A. 185, 175). Chlorinated ethers, e. g., C1CH 2 . OCH 3 , and zinc alkyls yield ethers of primary alcohols (B. 24, R. 858): 2C1 . CH 2 . OCH 3 + Zn(C 2 H 5 ) 2 = 2 C 2 H 5 . CH 2 . OCH 3 -f ZnCl 2 . In addition to the above universal methods, alcohols are formed by various other reactions. Their formation in the alcoholic fermenta- tion of sugars in the presence of ferments is of great practical import- ance. Appreciable quantities of methyl alcohol are produced in the dry distillation of wood. Many alcohols, too, exist as already formed natural products in compounds, chiefly as compound ethers of organic acids. Conversion of Primary into Secondary and Tertiary Alcohols. By the elimination of water the primary alcohols become unsaturated hydrocarbons CnH 2n (p. 91). The latter, treated with concentrated HI, yield iodides of secondary alcoholic radicals, as iodine does not attach itself to the terminal but to the less hydrogenized carbon atom (p. 93). Secondary alcohols appear when these iodides are acted upon with silver oxide. The successive conversion is illustrated in the following formulas : CH H H 00 ~> CH . OH &- k Isopropyl Isopropyl Iodide. Alcohol. Primary alcohols in which the group CH 2 .OH is joined to a secondary radical, pass in the same manner into tertiary alcohols : CI ^3\rTT rw OR -^ CH 3\r PR -v CH 3\rr PIT _^ CH Isobutyl Alcohol. Isobutylene. Tertiary Butyl Tertiary Butyl Iodide. Alcohol. The change is better effected by the aid of sulphuric acid. The sulphuric esters (p. 93), arising from the alkylens, C n H 2n , have the sulphuric acid residue linked to the carbon atom, with the least number of attached hydrogen atoms. Physical Properties. In physical properties alcohols exhibit a gradation corresponding to their increase in molecular weight. This Il6 ORGANIC CHEMISTRY. is true of other bodies belonging to homologous series. The lower alcohols are mobile liquids, dissolving readily in water, and possessing the characteristic alcohol odor and burning taste. As their carbon content increases, their solubility in water grows rapidly less. The normal alcohols, containing from one to sixteen carbon atoms, are oils at the ordinary temperature, while the higher are crystalline solids, without odor or taste. They resemble the fats. Their boiling points increase gradually (with similar structure) in proportion to the increase of their molecular weights. This is about 10 for the difference, CH 2 . The primary alcohols boil higher than the isomeric secondary, and the latter higher than the tertiary. Here we observe again that the boiling points are lowered with the accumulation of methyl groups (see p. 64). The boiling points can be calculated with approximate accuracy from the alkyl residues present (B. 20, 1948). The higher members are only volatile without decomposition under diminished pressure. Chemical Properties and Transpositions. The alcohols are neutral compounds. In many respects the first members of the series resemble water, and enter into combination with many salts, in which they play the role of water of crystallization (p. 118). Some of their more important transpositions are (1) The hydroxyl hydrogen is easily replaced by sodium, potassium, and other metals, yielding thereby the alcoholates. (2) In their interaction with strong acids water separates and com- pound ethers or esters are produced. This reaction is analogous to that taking place in the formation of a salt from a basic oxyhydrare and an acid. The alcohols figure as the base (p. 132). (3) The haloid esters of the alcohols are produced when the alcohols are heated together with the haloid acids. These esters are the monohalogen derivatives of the paraffins (p. 101). A more con- venient method for their formation consists in heating the alcohols with the phosphorus haloids. Nascent hydrogen, acting upon these esters, affords a means of reconverting the alcohols into their corresponding hydrocarbons (p. 101). (4) Energetic dehydrating agents change the alcohols, especially those of the tertiary class, into the olefines (p. 92). (5) Heated with phenols and zinc chloride, they yield homologous phenols (see these). Reactions, Distinguishing Primary, Secondary, and Ter- tiary Alcohols. (i) In the preliminary description of the alcohols it was clearly shown that primary alcohols, upon oxidation, yield aldehydes and carboxylic acids ; that the secondary alcohols form ketones with like carbon-content (p. in), and that the tertiary alcohols break down. (2) If the alcohols be converted by phosphorus iodide (p. loo) into their iodides, and the latter are changed by silver nitrite to nitroalkyls (see these), the latter com- LIMIT-ALCOHOLS, PARAFFIN ALCOHOLS. llj pounds will show characteristic color reactions, according as they contain a primary, secondary, or tertiary alcohol radical. (3) Acetic esters are formed when the primary and secondary alcohols are heated with acetic acid to 155 C. The tertiary alcohols, under similar treatment, split off water and form alkylens (A. 190, 343 ; 197, 193; 220, 165). (4) When the primary alcohols are heated together with soda-lime they yield their corresponding acids : R . CH 2 .OH + NaOH = R . CO .ONa + 2 H,. A. LIMIT-ALCOHOLS, PARAFFIN ALCOHOLS, C n H 2n + iOH. The most important members of this series, and of the monohydric alcohols in particular, are methyl alcohol or wood spirit, CH 3 . OH, and ethyl alcohol or spirits of wine : CH 3 . CH 2 . OH. x. Methyl Alcohol, Wood Spirit, Carbinol^Methanol^C^^. OH, differs from all other primary alcohols in that it contains the CH 2 OH group in union with hydrogen. Hence its oxidation is not restricted to the corresponding monobasic carboxylic acid, but may extend to carbonic acid : It is formed in large amounts in the dry distillation of wood. The name methyl, derived from /j.6u, wine, and tU^, wood, is a translation of wood spirit. History. Boyle discovered wood spirit in 1661 among the dry distillation products of wood. In 1812 Taylor recognized it as similar to spirits of wine, but considered it an entirely different body. Dumas and Peligot (1831) (A. 15, I) made the first careful study of it. . Methyl alcohol is also produced in the dry distillation of molasses. It occurs in nature as methyl salicylic ester, C 6 H 4 j f ]?? 3 winter- green oil, derived from Gaultheria procumbens. The full synthesis of methyl alcohol proceeds from carbon disulphide through methane, and methyl chloride, by action of aqueous caustic potash on the latter at 100 (Berthelot, 1858, A. chim. phys. [3] 52, 101): KOH CS 2 ^CH 4 ^CH 3 C1 ^CH 3 .OH. Physical Properties. Methyl alcohol is a mobile liquid with spiritu- ous odor and burning taste. It boils under 760 mm. at 66-67, ano ^ at 20 it has a specific gravity of o. 796. It mixes with water, alcohol, and ether. The aqueous product obtained in the distillation of wood at 500 in iron retorts con- tains methyl alcohol, acetone, acetic acid, methyl acetic ester, and other compounds. It is distilled over burnt lime or soda. The crude wood spirit which results contains Il8 ORGANIC CHEMISTRY. acetone as its chief impurity. To remove this add anhydrous calcium chloride. The latter combines with the alcohol to a crystalline compound. This is removed, freed from acetone by distillation, and afterward decomposed by distilling with water. Pure aqueous methyl alcohol passes over ; this is dehydrated with lime or potashes. To pro- cure it perfectly pure it is only necessary to break up oxalic methyl ester, the high- boiling methyl benzoate, or methyl acetic ester, with caustic potash. To detect ethyl in methyl alcohol, heat the latter with concentrated sulphuric acid, when acetylene will be formed from the first. Under this treatment methyl alcohol becomes methyl ether. The amount of methyl alcohol in wood spirit is determined, quantitatively, by converting it into methyl iodide, CH 3 I, through the agency of PI 3 (B. 9, 1928). We estimate the quantity of acetone by the iodoform reaction (B. 13, 1000). Uses. Wood spirit is employed as a source of heat. It is also used in making varnishes, dimethylaniline, and for the methylation of many carbon derivatives, particularly the dye-stuffs. It is a good solvent for many compounds of carbon. Chemical Properties. (i) It combines directly with CaCl 2 , to form CaCl 2 . 4CH 4 O, crystallizing in brilliant six-sided plates. Barium oxide dissolves in methyl alcohol, forming the crystalline body BaO . 2CH 4 O. The alcohol in this salt conducts itself like water of crystallization. (2) Potassium and sodium dissolve in anhydrous alcohol, to form methylates, e. g., CH 3 OK and CH 3 . ONa. (3) Oxidizing agents and also air, in presence of platinum black, change methyl alcohol to formic aldehyde, formic acid, and carbonic acid. (4) Chlorine and bromine do not act so readily upon methyl as upon ethyl alcohol. Chlorine attacks aqueous methyl alcohol quite easily (B. 28, R. 771). Dichlormethyl ether, (C1CH 2 ) 2 O, is first pro- duced; water converts it into formaldehyde and hydrochloric acid (B. 26, 268). (5) When methyl alcohol is heated with soda-lime, sodium formate results : CH 3 . OH -j- NaOH = CHO . ONa + 2H 2 . (6) When the alcohol is distilled over zinc dust, it breaks down into carbon monoxide and water. 2. Ethyl Alcohol, Spirits of Wine [Ethanof], C 2 H 5 . OH. In consequence of its formation in the spirituous fermentation of sac- charine plant juices, alcohol, in impure state, was known to the ancients. It was, however, only in the preceding century that the knowledge of how it might be obtained in an anhydrous condition was acquired. In 1808 Saussure determined its constitution. Occurrence. Ethyl alcohol seldom occurs in the vegetable kingdom. It is found, together with ethyl butyrate, in the unripe seeds of Heradeum giganteum and Hera- cleum spondylium. It is also present in the urine of diabetic patients, and in that of healthy men after excessive consumption of alcoholic beverages. Formation. It may be obtained by the general methods previously described for primary alcohols : (i) From ethyl chloride; (2) from ethyl sulphate; (3) from ethylene chlorhydrin ; (4) from ethylamine; LIMIT-ALCOHOLS, PARAFFIN ALCOHOLS. 119 (5) from aldehyde; and (6) from acetyl chloride. The synthesis of ethyl alcohol is, therefore, possible in two ways. The first three methods show that it is genetically connected with acetylene, ethylene, and ethane, while the last two methods indicate its relation to acety- lene and acetic acid (p. 112) : 2C+H2 Cl --> CH 3 OH C-f 28 Starting with acetylene, the most direct course to ethyl alcohol would be through acetaldehyde. Water converts it into the latter (p. 96), and nascent hydrogen then reduces the aldehyde to alcohol. If the acetylene be changed to ethylene, then various possibilities arise for the formation of ethyl alcohol: (i) Ethylene and hydrogen unite to form ethane, which chlorine changes to ethyl chloride, yielding alcohol when heated with water. (2) At 1 60 ethylene unites with sulphuric acid, forming ethyl sulphuric acid, which boiling water changes to ethyl alcohol and sulphuric acid. (3) Ethylene and hypochlorous acid yield ethylene chlorhydrin, which may be reduced to ethyl alcohol. A nucleus-synthesis of ethyl alcohol from methyl alcohol is possible through acetaldehyde. Methyl alcohol can be synthesized from carbon disulphide (p. 117). Phosphorus iodide converts the methyl alcohol into methyl iodide, and this, by action of potassium cyanide, is changed into methyl cyanide. Boiling alkali transforms the latter into an alkaline acetate, which phosphorus oxychloride converts into acetyl chloride. The latter, by reduction, yields ethyl alcohol, with acetaldehyde as an intermediate product. Acetaldehyde may also be prepared from calcium acetate by heating it with calcium formate. Preparation. Ethyl alcohol is prepared on a technical scale almost exclusively by what is termed the "spirituous fermentation" of sac- charine juices. Cagniard Latour, in 1836, and later Schwann, found that alcoholic fermentation was due to yeast germs an organized ferment (A. 29, 100 ; 30, 250, 363 ; A. chim. phys. [3], 58, 323). [These broke down the various sugars into alcohol and carbon 120 ORGANIC CHEMISTRY. dioxide. Yeast consists of microscopic cells (about o.oi mm. in size) : saccharomyces cerevisitz seu vini. Conditions of Alcoholic Fermentation. The yeast germs increase by budding. This takes place in dilute, warm (5-30) sugar solutions. It is most rapid at 20-30 C. The growth requires salts, especially phosphates, and albuminous substances. Oxygen is requisite at the commencement (B. 29, 1983), but the fermentation proceeds after- ward without air access. If the quantity of alcohol in a fermenting liquid reaches a certain amount, the fermentation ceases. The yeast germs can not grow in liquids containing 14 per cent, of alcohol. They are also destroyed by a temperature of 60, and by small quan- tities of phenol, salicylic acid, corrosive sublimate, and other disin- fectants. The sugars occurring in ripening fruits grapes, apples, cherries and in cane and beet sugars, as well as in many other plants, are the carbohydrates, which contain hydrogen and oxygen together with carbon in the same proportion in which the first two elements are present in water. The carbohydrates will be discussed immediately after the hexahydric alcohols : C 6 H 8 (OH) 6 mannitol, dulcitol, sor- bttol, etc., whose first oxidation products are the simple carbohydrates, C 6 H 12 O 6 . However, so much relating to the carbohydrates will be given at this time as appears necessary to understand alcoholic fer- mentation. The carbohydrates may be arranged into three principal classes : 1. Glucoses or Monoses, C 6 H 12 O 6 : grape sugar, fruit sugar, etc. 2. Saccharobioses, C la H M O u : malt sugar, cane sugar, milk sugar, etc. 3. Poly saccharines, (C 6 H 10 O 5 ) x : starch, dextrine, etc. The carbohydrates of the second and third classes bear the relation of anhydrides to the sugars of the first group. The simple sugars of the formula C 6 H 12 O 6 are capable of direct alcoholic fermentation. This is particularly true of grape and fruit sugar, as well as of malt sugar among the saccharobioses. Technic- ally, it is of the greatest importance that the not directly fermentable saccharobioses and the polysaccharides can be converted by water absorption into directly fermentable sugars, and these then be fer- mented. Unorganized Ferments or Enzymes. The breaking-down of saccharo- bioses and polysaccharides by water absorption (by hydrolysis] is induced by enzymes albuminoid-like compounds. The most im- portant of this class are invertin and diastase. Invertin is produced in the yeast germ. It is soluble in water and has acquired its name from the fact that it is capable of converting cane sugar into equimolecular quantities of grape sugar and fruit sugar so called invert sugar. At the same time the rotatory power of the liquid is reversed it is inverted. Cane sugar is dextro-rotatory. This is also true of grape sugar, whereas fruit sugar deviates the plane LIMIT-ALCOHOLS, PARAFFIN ALCOHOLS. 121 of polarized light more strongly toward the left, than an equivalent quantity of grape sugar turns it to the right. Consequently, inver- sion changes a dextro-rotatory cane-sugar solution into a laevo-rotatory solution of invert sugar : C 6 H 126 Grape Sugar, dextro-rotatory ~\ Invert Sugar, laevo- rotatory. C 12 H B U - Cane Sugar, dextro-rotatory. s. C 6 H 12 O 6 Fruit Sugar, laevo-rotatory Diastase is an unorganized ferment, produced in the germination of barley and other grains. The germination of the so-called green malt is interrupted by killing the germ by rapid drying. The malt is then subjected to kiln-drying, a. temperature which will not influence the activity of the diastase. At 50 to 60 the diastase in malt can hydrolyze the starch. Two-thirds of the latter are changed to malt sugar, which can be directly fermented by yeast. One-third of the starch becomes dextrine. This is converted much more slowly by the diastase into grape sugar. Malt sugar, like grape sugar, belongs to the saccharobioses. It absorbs water and is resolved into grape sugar. Milk sugar, also a saccharobiose, absorbs water and passes into a mixture of equimolecu- lar quantities of galactose and grape sugar. A review of these hydro- lytic relations is shown in the following diagram : CARBOHYDRATES . GLUCOSES, MONOSES C 6 H 12 6 Grape Sugar -4- Grape Sugar -4- Grape Sugar -4- Fruit Sugar -4 Grape Sugar -4~ Galactose -4~ Grape Sugar -4 SACCHAROBIOSES POLYSACCHARIDES (C 6 H 10 5 ) x Malt Sugar -4- Cane Sugar Milk Sugar Starch Dextrine The hydrolysis of the saccharobioses and of starch may also be brought about by warm, dilute sulphuric acid. This treatment changes the starch to grape sugar and dextrine. In technical opera- tions the preparation of saccharine juices from starchy compounds for the purpose of fermentation is executed almost exclusively by the diastase of malt. ii 122 ORGANIC CHEMISTRY. Pasteur considers that from 94 to 95 per cent, of sugar changes to alcohol and carbonic acid according to the equation : C 6 H 12 O 6 == 2C 2 H 6 O -f 2CO 2 . Fusel oil, some glycerol(2-$ per cent.) and succinic acid '(0.6 per cent.) are formed simultaneously, although the latter two appear generally toward the end of the fermentation (B. 27, R. 671). The fusel oil contains n propyl alcohol, isopropyl alcohol, isobutyl alcohol (CH 3 ) 2 CH . CH 2 OH, and especially amyl alcohol of fermentation a mix- /-TT ture of isobutyl carbinol, CH 3 >CH. CH 2 . CH 2 OH, and optically active - methyl-ethyl-carbin-carbinol, /->TT . CH 2 . OH (p. 128). Not only the varieties of saccharomyces, but also other budding fungi, I CHO CH,OH CHO CO,H Ethyl Alcohol. Glyoxal. Glycollic Acid. Glyoxk*b Acid. Oxalic Acid. ; oxalic Acii w: alcOTiolate Fulminating mercury (see this) is produced when alcohq|^t.s upon mercury and an excess of nitric acid. Alcoholates. Sodium ethylate is the most important alcO, by reduction, and from L,rl 2 formic ester by the aid of zinc and me'thyl iodide. Its formation from normal propyl- amine by the action of nitrous acid is rather interesting. Primary propyl alcohol and propylene are produced at the same time. The most practical method of obtaining it is to boil the iodide with ten parts of water and freshly prepared lead hydroxide in a vessel connected with a return con- denser, or simply by heating the iodide with twenty volumes of water to 100 (A. 1 86, 391). Oxidation changes it to acetone, while chlorine converts it into tetra- chloracetone (see this). Trichlorisopropyl Alcohol, CH 3 >CH. OH, is produced in the action of zinc methyl on chloral (p. 115). It is crystalline, fuses at 49, and boils about 155 (A. 210, 7 8). 4. Butyl Alcohols, C 4 H 9 .OH. According to theory four isomerides are possible : 2 primary, I secondary, and I tertiary (p. 109) : 126 ORGANIC CHEMISTRY. Name. Formula. M. P. B. P. Sp. Gr. I. Normal Butyl Alcohol, 2. Isobutyl Alcohol, . . CH 3 (CH 2 ) 2 CH 2 OH (CH 3 ) 2 CH.CH 2 OH Liquid 116.8 108.4 0.8099 at 20 0.8020 at 20 3. Secondary Butyl Alco- hol, L/ri 3 " 99 0.827 at o 4. Tertiary Butyl Alcohol, (CH 3 ) 3 C.OH 25 83 0.77883130 Normal Butyl Acohol, normal propyl carbinol [l-Butanol], forms in the action of sodium amalgam upon normal butyl aldehyde (Method, 43, p. 113). It is further produced by a peculiar fermentation of glycerol, brought about in the presence of a schizomycetes (B. 16, 1438; 29, R. 72). Trichlorbutyl Alcohol, CH 3 . CHC1 . CC1 2 . CH 2 . OH, results when zinc ethyl and butyl chloral (p. 114) are brought together, and is also obtained from urobutyl- chloralic acid. It fuses at 62, and boils under 45 mm. pressure at 120 (A. 213, 372). Methyl-ethyl Carbinol, secondary butyl alcohol, butylene hydrate, [2-Buta- nol], is a strongly-smelling liquid. It is obtained from normal butyl alcohol by its transposition into butylene, with the splitting-off of water, the addition of hydro- gen iodide, and finally the saponification of the iodide (p. 115). The same iodide is formed on heating erythrite with hydriodic acid. Heated to 24O-25o, it decomposes into water and /3-butylene, CH 3 . CH : CH . CH 3 . The genetic relations existing between the normal primary and secondary butyl alcohols, as well as between a-butylene and /3-butylene, are shown in the following arrangement : H 2 Isobutyl Alcohol, isopropyl carbinol, butyl alcohol of fermen- tation [methyl 2-propanol-i], occurs in several fusel oils and espe- cially in the spirit from potatoes. It is a liquid possessing a fusel-oil odor. It may be readily changed to isobutylene (CH 3 ) 2 C = CH 2 , from A^hich, by the addition of halogen hydrides, derivatives of ter- tiary butyl alcohol are obtained (p. 94). For the action of chlorine upon isobutyl alcohol see B. 27, R. 507 ; 29, R. 992. Trimethyl Carbinol, tertiary butyl alcohol [Dimethyl Ethanol], was prepared by Butlerow (1863) (A. 144, i) by the action of acetyl chloride upon zinc methyl (p. 114). It was the first representative of the class of tertiary alcohols predicted by Kolbe. The oxidation of tertiary butyl alcohol yields isobutyric acid (CH 3 ) 2 . CH . CO 2 H corresponding to isobutyl alcohol. This deportment may be explained by the intermediate formation of isobutylene (CH 3 ) 2 C = CH 2 , the conversion of the latter, by water absorption, into isobutyl alcohol and then oxidation of the latter (A. 189, 73). The isobutylene, resulting from isobutyl alcohol and tertiary butyl alcohol, by the withdrawal of water can, by the addition of C1OH and reduction of the resulting chlorhydrin, be changed to isobutyl alcohol, and by absorption of HI yield tertiary butyl iodide, which in turn may be transformed into tertiary butyl alcohol (p. 115). LIMIT-ALCOHOLS, PARAFFIN ALCOHOLS. 127 The boiling points of the haloid esters of the butyl alcohols will be given with the alkyl haloids (p. 140). Amyl Alcohols, C 5 H n . OH. Theoretically, 8 isomerides are possible : 4 primary alcohols, 3 secondary, and i tertiary. All are known. The following table contains the formulas and the boiling points of the eight amyl alcohols. The name amyl alcohol is derived from afwloy = starch, because the first-discovered amyl alcohol was observed in the fusel oil formed from the brandy of potato starch. Name. Formula. B. P. I. Normal Amyl Alcohol, . . 2. Isobutyl Carbinol, . . . CH 3 . (CH,). [CH 2 ] 3 CH 2 .OH .CHCH 2 .CH 2 OII 137 I3I-4 3. Active Amyl Alcohol, . . 4. Tertiary Butyl Carbinol, . . 5. Diethyl Carbinol, 6. Methyl n-propyl Carbinol, . (CH 3 ), (CH,. :H 2 > CH CH 2 H C . CH 2 OH CH 2 ) 2 CH . OH TH * "^3 "\fT-T f^TT 128.7 102 116 118.5 7. Methyl Isopropyl Carbinol, . (C H 3 ) 2 .CH- 112.5 8. Dimethyl Ethyl Carbinol, CH 3 (C C H |1:>-OH 102.5 Three of these eight alcohols contain an asymmetric carbon atom, indicated by a star, hence each can have three modifications, two optically active and one optically inactive modification (p. 46), which would raise the possible number of amyl alcohols to fourteen. (1) Normal Amyl Alcohol is most easily prepared from normal amylamine (from caproic acid) . It is almost insoluble in water, and has a fusel-oil odor. (2) Isobutyl Carbinol, (CH 3 ) 2 CH . CH 2 . CH 2 . OH, constitutes the chief ingredient of the amyl alcohol of fermentation obtained from fusel oil (p. 122), and occurs as esters of angelic and tiglic acids in Roman camomile oil. It may be obtained in a pure condition by synthesis from isobutyl alcohol, which it approaches in structure and with which it is associated in fusel oil : CH 2 .CHO CH 2 .CH 2 OH CH > CH CH 2 OH CH 2 I CH 2 CN CH 2 . CO 2 H CH > CH - > CH -> CH 5 A A A A CH S CH S CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 C A A The so-called alcohol of fermentation, possessing a disagreeable odor and boiling at 129-132, occurs in fusel oil and consists mainly of inactive isobutyl carbinol. In addition, methyl-ethyl carbinol (active amyl alcorrbl) is present. It rotates the plane of polarization to the left ; its activity is due to the presence of active amyl alcohol. 128 ORGANIC CHEMISTRY. Fermentation amyl alcohol, treated with sulphuric acid, yields two amyl sulphuric acids. The different solubilities and crystalline forms of their barium salts distin- guish them. From the more sparingly soluble salt, which forms in rather large quantity, isobutyl carbinol (Pasteur) may be obtained. A more complete separation of the alcohols is reached by conducting HC1 into the mixture. Isobutyl carbinol will be etherified first, the active amyl alcohol remaining (Le Bel) (A. 220, 149). The first upon oxidation yields inactive, and the second active valeric acid. When the crude fermentation alcohol is distilled with zinc chloride, ordinary amylene is the product. This consists mainly of (CH 3 ) 2 C : CH . CH 3 , resulting from a transposition of isobutyl carbinol ; it contains, besides, y-amylene and a-amylene (compare p. 94). CH 3\ * (3) Active Amyl Alcohol, ;CH. CH,. OH, secondary butyl carbinol, C 2 H/ methyl-ethyl-carbin-carbinol. Of the two active modifications, the laevo-rotatory form, not yet obtained pure, is the optically active constituent of the fermentation alcohol. Its quantity in the fermentation alcohol equals about 13 per cent., and its rotatory power is [a] 6 = 5.2. Its derivatives e. g., its chloride, bromide, iodide, and methyl-ethyl acetic acid (see valeric acid) are all optically active and indeed dextro-rotatory (B. 28, R. 410; 29, 59). Active amyl alcohol becomes inactive on boiling with NaOH (Le Bel). A mucor will render it again active, but dextro-rotatory (B. 15, 1506). (4) Tertiary Butyl Carbinol, (CH 3 ) 3 . C . CH 2 . OH, is formed on reducing the chloride of trimethyl-acetic acid or pivalic acid (B. 24, R. 557) with sodium amalgam. It melts at 48-50. Nitrous acid converts its amine, in consequence of a remarkable rearrangement of atoms, into dimethyl-ethyl carbinol (B. 24, 2161). (5) Diethyl Carbinol, (C 2 H 5 ) 2 . CH . OH, is formed by the action of zinc and ethyl iodide upon ethyl formate. Since /3-isoamylene, C 2 H 5 . CH : CH . CH 3 , yields C 2 H 5 . C 2 H . CHI . CH 3 with HI, from which methyl normal propyl carbinol is obtained, we can in this manner convert the diethyl carbinol into the latter alcohol : /3-Isoamylene. The two methyl propyl carbinols are obtained from methyl normal propyl ketone and methyl isopropyl ketone by reduction with sodium amalgam. # (6) Methyl Normal Propyl Carbinol, CH 3 . CH 2 . CH 2 . CH . OH . CH 3 , is made optically active (Le Bel) by Penicillium glaucum. The dextro-rotatory modi- fication is destroyed, and the Isevo-rotatory form remains. (7) Methyl Isopropyl Carbinol, (CH 3 ) 2 . CH . CH(OH) . CH 3 , yields, appar- ently, with the intermediate formation of amylene, when acted upon by halogen hydrides and also PC1 5 , the derivatives of tertiary amyl alcohol : CH 3 CH 2 CC1 CH 3 CH 3 The real derivatives of methyl isopropyl carbinol are obtained from a-isoamylene, (CH 3 ) 2 . CH . CH : CH 2 (p. 94), by the addition of halogen hydrides at ordinary tem- peratures or when warmed. HIGHER HOMOLOGUES OF THE LIMIT-ALCOHOLS. I2 9 (8) Tertiary Amyl Alcohol, ^ C ^j] 2 |c.OH, dimethyl ethyl carbinol, amy- lene hydrate, is a liquid with an odor like that of camphor. It produces sleep, the same as chloral hydrate, and is, therefore, made on a technical scale. Since ordinary amylene consists chiefly of /?-isoamylene (p. 94), tertiary amyl alcohol is most prac- tically prepared from the first by shaking it at 20 with sulphuric acid diluted with j^-l volume of water and boiling the solution with water (A. 190, 345). It is further formed by the action of nitrous acid on the amine of tertiary butyl car- binol (B. 24, 2519), and from propionyl chloride and zinc methide. At 200 it decom- poses into water and ,3-isoamylene. HIGHER HOMOLOGUES OF THE LIMIT-ALCOHOLS, CnH2n + i.OH. There are many representatives of the higher homologues of the alcohols of this series. Fourteen of the seventeen theoretically possible hexyl alcohols and thirteen of the thirty-eight theoretically possible heptyl alcohols have been prepared. The higher we ascend in the series, the larger the number of theoretically possible members and the smaller the number of those alcohols which are actually known. Only a few of them are noteworthy either from a point of formation, structure, or occurrence in the animal or vegetable kingdoms. In the following arrangement will be found chiefly the names, formulas, melting points, and boiling points of normal alcohols : Name. Formula. M. P. B. P. n-Hexyl Alcohol, CH., . (CH,),CH 9 . OH 157 Pinacolyl Alcohol, (CH 3 ) 3 CCHOH . CH 3 H-4 120 n- Heptyl Alcohol CH 3 (CH 2 )-CH 2 OH 175 Pentamethyl-ethyl Alcohol, . . (CH 3 ) 3 C.C(CH 3 ) 2 OH + 17 I3I n-Octyl Alcohol, Cetyl Alcohol or Ethal, .... Ceryl Alcohol or Cerotin, . . . Melissyl or Myricyl Alcohol, . . CH 3 .(CH 2 ) 6 .CH 2 OH CH 3 (CHJ U .CH 2 OH C 27 H 55 .OH C^H^.OH +49-5 79 85 199 34 n-Hexyl Alcohol occurs as acetic and butyric esters in the oil of the seed of Heracleuvi giganteum (A. 163, 193). Pinacolyl ALohol has a camphor- like odor. It results from the reduction of pina- coline (see this) or tertiary butyl methyl ketone, (CH 3 ) 3 .C. CO. CH 3 . See B. 26, R. 14, for its transposition products. r\-Ifeptyl Alcohol has been prepared from oenanthol (see this) by reduction and from n-heptane (A. 161, 278). n-Octyl Alcohol, C 8 H 17 OH, occurs as acetic ester in the volatile oil of Heracleum sphondylium, as butyric ester in the oil of Pastinaca sativa, and in the oil of Herac- leum giganteum (A. 185, 26). Cetyl Alcohol, C 16 H 33 . OH, Hexadecyl Alcohol, formerly called ethal, is a white, crystalline mass fusing at 49.5, and distilling about 340. It was prepared in 1818 by Chevreul from the cetyl ester 13 ORGANIC CHEMISTRY. of palmitic acid, the chief ingredient of spermaceti, by saponification with alcoholic potash : C V 6 - H B>0 + KOH == C 16 H 33 . OH + C 16 H 31 . OK. ^"33 Ethal. Potassium Palmitate. It yields, when fused with potassium hydroxide, palmitic acid (p. 117): C 15 H 31 CH 2 OH 4- KOH = C 15 H 31 COOK -f 2 H 2 . Ceryl Alcohol, C 27 H 55 . OH, cerotin, as ceryl cerotic ester, C 2; H 53 O . O . C 27 H 55 , constitutes Chinese wax. It is obtained by melting the latter with caustic potash. Ceryl alcohol is a white, crystalline mass, fusing at 79. It yields cerotic acid when fused with potassium hydroxide. Melissyl Alcohol, C 30 H 61 . OH, myricyl alcohol^ occurs as myricyl palmitate in beeswax. It is isolated in the same manner as the preceding compound, and melts at 85. Its chloride melts at 64, and the iodide at 69.5. Myricyl iodide and metallic sodium gave Hexacontane, C^H^^ or dimyricyl (p. 84). B. UNSATURATED ALCOHOLS. I. OLEFINE ALCOHOLS, CnH2n-l.OH. These are derived from the unsaturated alky lens, C n H 2n , in the same manner as the normal alcohols are obtained from their hydrocarbons. In addition to the general character of alcohols, they are also capable of directly binding two additional affinities. The chief representative of the class is allyl alcohol, CH 2 = CH . CH 2 OH. When oxidized by potassium permanganate, the double linkage of the allyl alcohols is severed, and trihydric alcohols glycerols result (B. 21, 3347). i. Vinyl Alcohol, vinol, CH 2 : CH . OH, separates as C 2 H 3 O 2 Hg 3 Cl 2 from ethyl ether on the addition to it of an alkaline mercury monoxychloride solution (Poleck and Thiimmel, B. 22, 2863). It is simultaneously produced with hydrogen peroxide when ether is oxidized with atmospheric oxygen. It cannot be separated from its mercury derivative because in all the reactions in which it should form, the isomeric acetaldehyde, CH 3 . CHO, is produced (p. 53). It seems to be the universal rule that the atomic grouping = C : CH . OH, in the act of formation, is transposed into CH.CHO (Erlenmeyer, Sr., B. 13, 309; 14, 320); however, there are more stable bodies than vinyl alcohol, in which the groupings = C = CH . OH and C = C(OH)R (p. 131) are present. The haloid esters of vinyl alcohol are to be considered the monohalogen substitu- tion products of ethylene (p. 105). Vinyl ether and vinyl ethyl ether are known (p. 136). The radical vinyl is present in neurine, so important physiologically. 2. Allyl Alcohol [/V^0 + S0 4 H 2 . Ethyl Sulphuric Diethyl Acid. Ether. SO * + SO * H *- Methyl Sulphuric Methyl-ethyl Acid. Ether. When a mixture of two alcohols is permitted to act upon sulphuric acid, three ethers are simultaneously formed ; two are simple and one is a mixed ether. Other polybasic acids, like phosphoric, arsenic, and boric, behave like sulphuric acid. This is also true of hydrochloric acid at 170, and sulpho-acids e. g., benzene sulphonic acid, at 145 (F. Krafft, B. 26, 2829). In this reaction ethyl benzene sulphonic ester is pro- duced and breaks down in the sense of the equations: C 6 H,S0 3 H + C 2 H 5 OH = C,H 5 S0 3 C 2 H 5 + H 2 O. C 6 H 5 S() 3 C 2 H 5 + C 2 H 5 OH = C 6 H 5 S0 3 H + (C 2 H 5 ) 2 O. 2. The action of the alkylogens upon the sodium alcoholates in alcoholic solution. Mixed ethers are also formed here : C 2 H 5 . ONa + C 2 H 5 C1 = 5 >O '+ NaCl. ^2 n 5 C 2 H 5 . ONa + C 3 H 7 C1 = &2 5 >O + NaCl. ^3 H 7 Consult B. 22, R. 381, 637, upon the speed of these reactions. 3. Action of the alkylogens upon metallic oxides, especially silver oxide : 2C 2 H 5 I -f Ag 2 = (C 2 H 5 ) 2 -f 2AgI. The constitution of ethers is indicated in this reaction. Properties. Ethers are neutral, volatile (hence the name al^tjp, air) bodies, nearly insoluble in water. The lowest members are gases ; the next higher are liquids, and the highest e. g., cetyl ether are solids. Their boiling points are very much lower than those of the corresponding alcohols (A. 243, i). Transpositions. Chemically, ethers are very indifferent, because all the hydrogen is attached to carbon. (i) When oxidized they yield the same products as their alcohols. (2} They yield ethereal salts when heated with concentrated sulphuric acid. (3) Phosphorus chloride converts them into alkyl chlorides : PC1 5 = C 2 H 5 C1 -f CH 3 C1 -f- POC1 3 . 134 ORGANIC CHEMISTRY. (4) The same occurs when they are heated with the haloid acids, especially with HI : C ? H 3 5 > + 2HI = C 2 H 5 T + CH 3 I + H 2 0. When acted upon by HI in the cold, they decompose into alcohol and an iodide. With mixed ethers it is the iodide of the lower radical that is invariably produced (B. 9, 852 ; 26, R. 718). (5) Many ethers, especially those with secondary and tertiary alkyls and those with unsaturated alkyls (allyl), break up into alcohols (B. 10, 1903) when heated with water or dilute sulphuric acid to 150. A. ETHERS OF THE SATURATED OR PARAFFIN ALCOHOLS. Methyl Ether, (CH 3 ) 2 O, is prepared by heating methyl alcohol with sulphuric acid (B. 7, 699). It is an agreeable-smelling gas, which may be condensed to a liquid at about 23. Water dissolves 37 volumes and sulphuric acid upward of 600 volumes of the gas. Chlorine converts ether into chlormethyl ether, s-dichlormethyl ether, and pei- chlormethyl ether, which decomposes on boiling. The first two are formaldehyde derivatives, and, together with the corresponding brom- and iodo-compounds, will be treated after formaldehyde. Ethyl Ether or Ether, (C 2 H 5 ) 2 O, is by far the most important representative of this class of compounds. It has been known for a long time. History. Ethyl ether and its production from alcohol and sulphuric acid were known in the sixteenth century. They were described toy Valerius Cordus, a German physician. Until the beginning of the present century ether was regarded as a sulphur-containing body ; hence, to distinguish it from other ethereal compounds, it was called sulphiir-ether. The ether process, in which a comparatively small quantity of sulphuric acid was capable of converting a large quantity of alcohol into ether, was included in the category of catalytic reactions. The explanation of this process constitutes one of the most brilliant advances in organic chemistry. In 1842, Gerhardt, from purely theoretical reasons and in opposition to Liebig, concluded that the ether molecule did not contain the same number of carbon atoms as were present in the alcohol molecule, but exactly twice that number. He was unable to gain general acceptance for this view. Williamson, in 1850, by a new synthesis of ether, proved the correctness of Gerhardt's conception, not only for it, but for ethers in general. His method was the transposition taking place between sodium ethylate and ethyl iodide (p. 133). The formation of ether from alcohol and sulphuric acid Williamson explained by a continuous breaking-down and re-formation of ethyl sulphuric acid, made possible by the contact of alcohol with the acid at 140 (A 77, 37; 81, 73). Chancel, who preceded Williamson in publication, had made ether independently of the latter, by heating a mixture of potassium ethyl sulphate and potassium ethylate : The objection that ether, because of its low boiling temperature, could not contain the double number of carbon atoms in its molecule, Chancel removed by citing the boiling point of ethyl acetic ester (Compt. rend, par Laurent et Gerhardt (1850), 6, 369)- ETHERS OF THE SATURATED OR PARAFFIN ALCOHOLS. Ethyl Alcohol, . . . C 2 H 5 OH, . . . . boils at 78. Ether, (C 2 H 5 ) 2 O, .... boils at 35. Acetic Acid, . . . . CH 3 CO 2 H, . . . boils at 118. Ethyl Acetic Ester, . CH 3 . CO 2 . C 2 II 5 , . boils at 77. Thus was proved that ethyl alcohol and ether were bodies belonging to the water type (p. 35) /. e. , they might be regarded as water in which one and two hydrogen atoms were replaced by ethyl : l~> TJ 1 r* T.T \ O. Preparation. Ether is made (i) from ethyl alcohol and sulphuric acid heated to 140. The process is continuous. (2) From benzene sulphonic acid and alcohol at 135-145 (B. 26, 2829). The advantage in the second method is that the ether is not contaminated with sulphur dioxide, which in the first method is removed from the crude product by washing with a soda solution. Anhydrous ether may be obtained by distilling ordinary ether over burnt lime, and drying it finally with sodium wire (see aceto- acetic ester) until there is no further evolution of hydrogen. Test for Water and Alcohol. When ether containing water is shaken with an equal volume of CS 2 , a turbidity results. When alcohol is present, the ether, on shaking with aniline violet, is colored. Anhydrous ether does not acquire a color, when similarly treated. Properties. Ethyl ether is a mobile liquid with peculiar odor, and specific gravity at o of 0.736. When anhydrous, it does not congeal at 80. It boils at 35 and evaporates very rapidly even at medium temperatures. It dissolves in 10 parts of water and is miscible with alcohol. Nearly all the carbon compounds insoluble in water, such as the fats and resins, are soluble in ether. It is extremely inflammable, burning with a luminous flame. Its vapor forms a very explosive mixture with air. When inhaled, ether vapor brings about uncon- sciousness, a property discovered in 1842 by Charles Jackson, of Boston, hence its use in surgical operations.* Hoffmann' s Anodyne (so named after the great Halle clinician, who died in 1742) is a mixture of 3 parts alcohol and i part ether. Ether unites with bromine to form peculiar, crystalline addition products, some- what like bromine hydrate ; it combines, too, with water and metallic salts. Transpositions. For the action of air on ether see vinyl alcohol (p. 130). Hy- drogen peroxide is produced when oxygen acts on moist ether (B. 29, R. 840). When heated with water and sulphuric acid to 1 80, ethyl alcohol results. When ozone is conducted into anhydrous ether, an explosive peroxide is formed. Chlorine, acting upon cooled ether, produces (A. 279, 301) : Monochlor-ether, CH 3 . CHC1 . O . C 2 H 5 , boiling at 98. i. 2-Dichlor-ether, CH 2 C1 . CHC1 . O . C 2 H 5 , boiling at 145. Trichlor-et/u-r, CHC1, . CHC1 . O . C 2 H 5 , boiling at 102 (100 mm.). Perchlor-ether, (C^Cl^O, melting at 68. It breaks down on distillation into C 2 C1 6 and trichlor-acetyl chloride, C 2 C1 3 O . Cl. 2-C1-, Br-, \-ethyl ethers are the ethers of glycol-, chlor-, brom-, and iodhydrins e.g., CH 2 C1.CH 2 .O.C 2 H 5 . Der Aether gegen den Schmerz, von Binz in Bonn, 1896. 136 ORGANIC CHEMISTRY. ^-Dichlor- ether, CH 3 . CHC1 . O. CHC1 . CH 3 , boiling at 1 16, is produced by the action of hydrochloric acid upon aldehyde. The following table contains the melting and boiling points of the better known simple and mixed ethers : Ethyl methyl ether boils at 1 1 ; n-propyl-m ethyl ether boils at 50 ; n-propyl ether boils at 86; isopropyl ether boils at 60-62; isoamyl ether boils at 176; Cetyl ether, (C 16 H 33 ) 2 O, melts at 55 and boils at 300. B. ETHERS OF UNSATURATED ALCOHOLS. It was explained, when discussing the unsaturated alcohols (p. 130), that the members of that series in which hydroxyl was combined with a doubly linked carbon atom readily rearranged themselves into aldehydes or ketones, and were only known in their derivatives, especially as ethers. Thus : i. Vinyl ether, (CH 2 = CH) 2 O, boils at 39, and may be obtained from vinyl sulphide (p. 149) and silver oxide. 2. Pcrchlor-vinyl ether, Chloroxethose, (CC1 2 ^= CC1) 2 O, is formed from perchlorethyl ether (p. 135) and K 2 S. 3. Vinyl ethyl ether, boiling at 35-5, results from the interaction of iodoethyl ether and sodium ethylate. 4. Isopropenyl-ethyl ether, CH 3 C(OC 2 H 5 ) = CH 2 , formed from propenyl bro- mide and alcoholic potash, or from ethoxycrotonic acid (B. 29, 1005), boils at 6263. Ethers of allyl alcohol and propargyl alcohol are known : Allyl ether, (CH 2 = CH . CH 2 ) 2 O, boils at 85 ; propargyl ethyl ether, CH = C . CH 2 . O . CH 2 . CH 3 , boils at 80. See ethyl propiolic ester. 2. ESTERS OF THE MINERAL ACIDS. If we compare the alcohols with the metallic bases, the esters or compound ethers (p. 132) are perfectly analogous in constitution to the salts. Just as salts result from the union of metallic hydroxides with acids, so esters are formed by the combination of alcohols with acids. Water appears as a side-product in both reactions : NaOH-fHCl= NaCl + H 2 0. C 2 H 5 OH + HC1 = C 2 H 5 C1 -f H 2 O. The haloid esters correspond to the haloid salts ; they may also be regarded as monohalogen substitution products of the hydrocarbons (p. 101). Corresponding to the oxygen salts are the esters of other acids, which, therefore, may be viewed as derivatives of the alcohols, in which the alcohol-hydrogen has been replaced by acid radicals, or as derivatives of the acids, in which the hydrogen replaceable by metals has been substituted by alcohol radicals. The haloid esters would be included in the last definition of esters. The various definitions of esters as derivatives of the acids, and again as derivatives of the alco- hols, find expression in the different designations of the esters : C 2 H 5 . . NO 2 or NO 2 . O . C,H 5 . Ethyl Nitrate. Nitric Ethyl Ester. In polybasic acids all the hydrogen atoms can be replaced by alco- hol radicals resulting in the production of neutral esters. When alco- hol radicals are introduced for all of the hydrogen atoms add esters are formed. These still possess the acid character. They form salts, hence are termed ether acids, and correspond to acid salts : ESTERS OF THE MINERAL ACIDS. 137 SO ^ OK SO ^ OK 3 2 ^O ^2^5 QH .x-O CjH g 3(J 2<0 . OHj 3U 2 CH 3 . CPU . CH 3 HI (3) From alcohols (a) by the action of haloid acids. This reaction does not readily complete itself unless the halogen hydride is used in great excess, or the water formed at the same time with the alkylogen is absorbed. Hence in the case of methyl and ethyl alcohol an addi- tion of zinc chloride or sulphuric acid is advantageous (see mono-chlor- methane, p. 141). This addition is a disadvantage with the higher alcohols, because then olefines are first produced, and to these the halogen hydride adds itself in such a manner that an isomeride of the desired alkylogen is obtained (p. 92). It may also be remarked that in the presence of an excess of hydriodic acid the iodides are often reduced. Hence alkyl iodides can be prepared from polyhydric alcohols (compare isopropyl iodide, p. 142) : C 2 H 4 fOH) 2 + 3 HI = C 2 H 5 I + I 2 + 2H 2 0. C 3 H 5 (OH) 3 + 5 HI = C 3 H 7 + 2 I 2 + 3 H 2 0. C 4 H 6 (OH) 4 + 7 HI = C 4 H 9 I + 3 I 2 -f- 4 H 2 0. C 6 H 8 (OH) 6 + iiHI = C 6 H 13 I + 5I 2 + 6H 2 0. (b) By the action of phosphorus halides. If, for example, ethyl ALK.YL ESTERS OF THE HALOID ACIDS. 139 alcohol be treated with PC1 3 , PBr 3 , or PI 3 , two possibilities arise : either an halogen hydride and ethyl phosphorous ether are produced, or an ethyl haloid and phosphorous acid. The latter reaction occurs when PBr 3 and PI 3 are used, and this method is adopted almost exclusively in the preparation of the alkyl bromides and iodides (see ethyl bromide and ethyl iodide) : PBr 3 + 3C.H.OH = 3 C 2 H 5 Br + PO 3 H 3 PI S + 3 C 2 H 5 OH= 3 C 2 H 5 I + P0 3 H 3 . (BI 3 acts analogously upon ethyl alcohol, B. 24, R. 387). The formation of esters of phosphorous acid by the use of PBr 3 and PI 3 is far from satisfactory. PC1 3 , on the other hand, yields phosphorous esters and hydrochloric acid almost entirely according to the equation : PC1 3 + 3 C 2 H 5 OH = P(0 . C 2 H 5 ) 3 + 3 HC1. The chlorides are readily formed if PC1 5 be substituted for PC1 3 : PC1 5 -f C 2 H 5 OH = C 2 H 5 C1 + HC1 + POC1 3 . (4) From alkyl-haloids or alkyl sulphuric acids and metallic halides. (a) Bromides and iodides can be transformed into chlorides by heating them with HgCl 2 : 2C 3 H 7 I + HgCl 2 = 2C 3 H 7 C1 + HgT 2 . (b) When chlorides are heated with AlBr 3 or A1I 3 or CaI 2 they become bromides or iodides (B. 14, 1709 ; 16, 392 ; 19, R. 166) : 3 C 2 H 5 C1 + AlBr 3 = 3 C 2 H 5 Br + A1C1 3 . (c) Methyl and ethyl iodides yield with AgFl the gaseous compounds methyl fluoride, CH 3 F1, and ethyl fluoride, C 2 H.F1, which have an agreeable, ethereal odor, and do not attack glass (B. 22, R. 267). (d) On distilling ethyl sulphuric acid and potassium bromide, ethyl bromide is produced. Isomerism. Propane is the first hydrocarbon yielding isomerides (p. 43). The isomerism depends o'n the varying position of the hydrogen atoms in the same carbon chain, and from butane forward it depends on the different linkage of the carbon atoms forming the carbon skeleton (see table, p. 140). Properties and Transpositions. The alkylogens are ethereal, agree- able, sweet-smelling liquids. They are scarcely soluble in water, but dissolve with ease in alcohol and ether. They are gases at the ordi- nary temperature e. g., methyl chloride, ethyl chloride, and methyl bromide. The chlorides boil 28-2o lower than the bromides, and the latter from 34-28 lower than the corresponding iodides (p. 140). The differences grow less with increasing molecular weight. As in the case of the hydrocarbons, so here it may be said that where isomerides exist, the normal members have the highest boiling points. The more branched the carbon chain, the lower will the boiling point lie. As haloid esters of the alcohols, the alkylogens may be compared with 140 ORGANIC CHEMISTRY. the metallic halides, although the halogens are less readily transposed by silver nitrate. The iodides are the most reactive. However, the alkylogens are excellently adapted to bring about the replacement of metals, and thus unite atoms previously in union with metals, to alcohol radicals. Particularly interesting is the transposition occa- sioned by the alkaline cyanides (see nitriles), and the sodium deriva- tives of aceto-acetic ester (see this) and malonic ester (see this). Both are synthetic reactions of the first importance (p. 81). The alkylogens play a prominent part in the nucleus-syntheses of the paraffins (see ethane, p. 82). They constitute the transition from the paraffins and defines to the alcohols (see these), into which they are converted by moist silver oxide. The methods for the transposition of alcohols into ethers, into mercaptans, into alkyl sulphides (sulphur ethers) and compound mineral ethers or esters, are based upon the reactivity of the halogen atoms in the alkylogens! This is also the case with the methods employed in the preparation of metal alkyls. Among the numerous reactions of the alkylogens, mention may here be made of their power to unite with ammonia and ammonium bases. By this means the primary, secondary, and tertiary amines, as well as the tetra alkyl ammonium halides, were obtained. The following table contains the boiling points of some of the alkylogens at the ordinary pressure : Name and Formula of Radical. Chloride. Bromide. Iodide. Methyl-, Ethyl-, CH 3 _ CH 3 . CH 2 _ -2 4 4-12.5 +4-5 38 43 7 2 Norm. Propyl-, Isopropyl- CH 3 . CH 2 . CH 2 (CH 3 ) 2 CH_ 44 36-5 59-5 102 8 9 .5 Norm. Butyl-, .... CH 3 .CH 2 .CH 2 .CH 2 _ (CH 3 ) 2 .CH.CH 2 _ (CH 3 ) 3 C_ 77-5 68.5 100.4 92 129.6 120 120 I03.3 Isobutyl-, Sec. Butyl-, Tert. Butyl-, 51-5 72 Norm. Amyl-, Isoamyl- .... ... CH 3 . (CH 2 ) 3 CH 2 _ (CH 3 ). 2 CH.CH 2 .CH. 2 _ (C 2 H 5 ) 2 CH_ CH 3 . CH 2 . CHj >CH CH 3>CH (CrI 3 ) 2 Cri 106 100 104 91 86 129 120 113 115 100 155 148 145 144 138 127 Diethyl Methyl-, Methyl-norm.-propyl Methyl-, Methyl-isopropyl-methyl-, Dimethyl-ethyl-methyl-, . . Norm. Hexyl-, Norm. Heptyl-, CH 3 .[CH 2 ] 4 .CH 2 _ CH 3 . [CH 2 ]..CH 2 _ CH 3 . [CH 2 ] 6 .CH 2 _ 133 1 80 155 178 199 179 203 225 Norm. Octyl-, HALOID ESTERS OF THE SATURATED ALCOHOLS. 14! Monochlormethane, CH S C1, Methyl Chloride, is obtained from methane or methyl alcohol. It is a sweet-smelling gas. Alcohol will dissolve 35 volumes of it, and water 4 volumes. It is prepared by heating a mixture of I part methyl alcohol (wood spirit), 2 parts sodium chloride, and 3 parts sulphuric acid. A better plan is to conduct HC1 into boiling methyl alcohol in the presence of zinc chloride (^ part). The disengaged gas is washed with KOH, and dried by means of sulphuric acid. Commercial methyl chloride usually occurs in a compressed condition. It was formerly applied in the manufacture of the aniline dyes, and in producing cold. It is obtained by heating trimethylamine hydrochloride, N(CH 3 ) 3 . HC1. Monochlorethane, C 2 H 5 C1, Ethyl Chloride, is an ethereal liquid, boiling at 12.5 ; specific gravity at o 0.921. It is miscible with alcohol, but is sparingly soluble in water. It is prepared from ethyl alcohol in the same manner that methyl chloride is obtained from its alcohol. Its formation from ethyl hydride or dimethyl by means of chlorine (p. 83) is important from a theo- retical standpoint. If heated with water to 100 (in a sealed tube), it changes to ethyl alcohol. The conversion is more rapid with potassium hydroxide. In dispersed sunlight, chlorine acts upon it to form ethylidene chloride, CH 3 . CHC1 2 , and other substitution products. Of these C 2 HC1 5 was formerly employed as ALther ancestheticus. Chlorine converts ethyl chloride, in the presence of iron, into ethylene chloride. The boiling points of the two propyl chlorides, the three butyl chlorides, six amyl chlorides, normal hexyl-, heptyl-, and octyl-chlorides, have been given in the preceding table. Myricyl chloride, CH 3 [CH 2 ] 28 CH 2 C1, melts at 64. Methyl Bromide, CH 3 Br Monobrommethane. Specific gravity is 1.73 at o. Ethyl Bromide, C 2 H 5 Br, boils at 39 ; its specific gravity is 1.47 at 13. Bromine (6 pts.) is run into a mixture of red phosphorus (i pt.) and 95 per cent, alcohol (6 pts.). The mixture should be chilled and constantly shaken while introducing the bromine. The reaction will be complete at the expiration of several hours. The ethyl bromide is then distilled off, washed first with a soda solution, then with water, and rectified after previous drying over calcium chloride. Ethyl bromide is the officinal sEther bromatus. It is prepared from potassium bromide and ethyl sulphuric acid (p. 139). It is used as a narcotic. Propyl Bromide, C 3 H 7 Br, from the normal alcohol, boils at 71; its specific gravity is 1.3520 at 20. Isopropyl Bromide, C 3 H 7 Br, from its corresponding alcohol, boils at 59.5 ; its specific gravity is 1.3097 at 20. It is most conveniently obtained by the action of bromine upon isopropyl iodide (B. 15, 1904). Upon boiling with aluminium bromide, or by heating to 250, normal propyl bromide passes over into the isopropyl bromide (not completely, however) (B. 16, 391). Such a transposition, due to displacement of the atoms in the molecule, occurs rather frequently, and is termed molecular transposition. It maybe assumed that the normal propyl bromide, CH 3 . CH 2 . CH 2 . Br, at first breaks up into propylene, CH 3 . CH : CH 2 and HBr (see p. 91), which then, according to a common rule of 142 ORGANIC CHEMISTRY. addition (p. 93), unites with the propylene to isopropyl bromide, CH 3 . CHBr . CH 3 . Similarly, isobutyl bromide, (CH 3 ) 2 . CH . CH 2 . Br, changes at 240 to tertiary butyl bromide, (CH 3 ) 2 . CBr . CH 3 . The transpositions occurring on heating the halogen hydrides with the alcohols may be explained in the same manner. The table already referred to also contains the boiling points of some of the higher homologues. Cetyl Bromide, CH 3 [CH 2 ] u CH 2 Br, melts at 15. On exposure to the air the iodides soon become discolored by depo- sition of iodine. The iodides of the secondary and tertiary alcohols are easily converted by heat into alkylens, C n H 2n and HI. Consult A. 243, 30, upon the specific volumes of the alkyl iodides. Methyl Iodide, CH 3 I, is a heavy, sweet-smelling liquid, boiling at 43, and has a specific gravity of 2.19 at o. In the cold it unites with H 2 O to form a crystalline hydrate, 2CH 3 I -f H 2 O. Ethyl Iodide, C 2 H 5 I, is a colorless, strongly refracting liquid, boiling at 72 and having a specific gravity of 0.975 at o. It was dis- covered by Gay-Lussac in 1815. It is prepared similarly to ethyl bro- mide. Propyl Iodide, C 3 H,I, from propyl alcohol, has a specific gravity of 1.7427 at 20. Isopropyl Iodide, C 8 H 7 I, is formed from isopropyl alcohol, pro- pylene glycol, C 3 H 6 (OH) 2 , or from propylene, and is most conveni- ently prepared by distilling a mixture of glycerol, amorphous phos- phorus, and iodine (A. 138, 364) : C 3 H 5 (OH) 3 + 5HI = C 3 H 7 I + 2I 2 + 3 H 2 0. Here we have allyl iodide, CH 2 = CH CH 2 I, produced first (see below), and this is further changed to propylene, CH 2 = CH CH 3 , and isopropyl iodide. Isopropyl Iodide boils at 89.5, and has a specific gravity of 1.7033 at 20. The boiling points of some of the higher alkylogens will be found in the pre- ceding table. Cetyl iodide, CEL. [CH 2 ] 14 CH 2 I, melts at 22, and myricyl iodide, CH 3 [CH 2 ] 28 CH 2 I,at 7 o. II. HALOID ESTERS OF THE UNSATURATED ALCOHOLS. Only the haloid esters of the most important olefine and acetylene alcohols will be given; they are the allyl haloids and the propargyl haloids. The former are prepared from allyl alcohol by methods similar to those employed for the preparation of the corresponding compounds from ethyl alcohol. They are isomeric with the /?- and a-haloid propylenes (p. 105), from which they are distinguished by their adaptability for double decompositions: Formula. Boiling Point. Sp. Gravity. Allyl Fluoride (B. 24, R. 40), Allyl Chloride, Allyl Bromide CH 2 = CH.CH 2 F1 CH 2 = CH.CH 2 C1 CH 2 CH .CH 2 Br 10 46 71 0.9379 (20) I 4.61 ( Q Q \ Allyl Iodide, CH 2 = CH.CH 2 I 101 1.789 (16) ESTERS OF NITRIC ACID. 143 The allyl haloids are liquids with leek-like odor. Allyl chloride, heated to 100 with HC1, yields propylene chloride, CH 3 . CHC1 . CH 2 C1. Allyl bromide, heated to 100 with HBr, passes into trimethylene bromide, CH 2 Br . CH 2 . CH 2 Br. The addi- tion of halogens produces glycerol trihaloid esters. Allyl Iodide. This is most frequently used. It is readily prepared from glycerol by the action of HI, or iodine and phosphorus. It may be supposed that at first CH 2 I . CHI . CH 2 I forms, but is sub- sequently decomposed into allyl iodide and iodine. (Preparation : A. 185, 191 ; 226, 206.) With excess of HI or phosphorus iodide, allyl iodide is further converted into propylene and isopropyl iodide (see above). By continued shaking of allyl iodide (in alcoholic solution) with mercury, C 3 H 5 HgI separates in colorless leaflets (see mercury ethyl). Iodine liberates pure allyl iodide from this : C 3 H 5 HgI + I 2 = C 3 H 5 I -f HgI 2 . Alcoholic potash converts allyl iodide into allyl ethyl ether. With potassium sulphide it yields allyl sulphide (p. 150); with potassium stilphocyanide, allyl sulphocyanide, which passes readily into allyl mustard oil (see this). Allyl iodide has also been used in the syn- thesis of unsa'turated alcohols. Name. Formula. Boiling Point. Sp. Gravity. Propargyl Chloride (B. 8/398), . Propargyl Bromide (B. 7, 761), . Propargyl Iodide (B. 7, 1132), . CH = C.CH 2 C1 CH = C.CH 2 Br CH = C . CH 2 I 65 89 115 1-0454 ( 5) 1.5200 (20) 2.0177 ( o) Propargyl chloride is produced when phosphorus trichloride acts upon propargyl alcohol. B. ESTERS OF NITRIC ACID. They are prepared by the interaction of alcohols and nitric acid. Nitrous acid is always produced. It is a consequence of oxidizing, secondary reactions, and may be destroyed by the addition of urea: CO(NH 2 ) 2 -f 2HN0 2 = C0 2 -f 2N 2 -f 3 H 2 O. When much nitrous acid is present, it induces the decomposition of the nitric acid ester, and causes explosions. Methyl Nitrate, CH 3 .O. NO 2 , Nitric Methyl Ester, boils at 66, and has a specific gravity, at 20, of 1.182. When struck or heated to 150 it explodes very violently. Ethyl Nitrate, C 2 H 5 . O . NO 2 , Nitric Ethyl Ester. Ethyl nitrate is a colorless, pleasant-smelling liquid, boiling at 86, and having a specific gravity of 1.112, at 15. It is almost insoluble in water, and burns with a 144 ORGANIC CHEMISTRY. white light. It will explode if suddenly exposed to high heat. Heated with ammonia, it passes into ethylamine nitrate. Tin and hydrochloric acid convert it into hydroxylamine. Tihepropyi ester, C 3 H 7 .0 . NO 2 , (B. 14, 421) boils at no , the isopropyl ester at 101-102, and the isobutyl ester at 123. C. ESTERS OF NITROUS ACID. These are isomeric with the nitro-paraffins. The group NO 2 is present in both; while, however, in the nitro-compounds nitrogen is combined with carbon, in the esters the union is effected by oxygen : C 2 H 5 . NO 2 C 2 H 5 . O . NO. Nitro-ethane. Nitrous Ethyl Ester. The nitrous esters, as might be inferred from their different structure, decompose into alcohols and nitrous acid when acted on by alkalies. Similar treatment will not decompose the nitro-compounds. Nascent hydrogen (tin and hydrochloric acid) converts the latter into amines, while the esters are saponified. Nitrous acid esters are produced in (l) the action of nitrous acid upon the alcohols ; (2) by the action of alkyl iodides upon silver nitrite (B. 25, R. 571). Nitro-paraffins, with high boiling points, are formed simultaneously. Methyl Nitrite, Nitrous Methyl Ester, CH 3 . O . NO, boils at 12. Ethyl Nitrite, Nitrous Ethyl Ester, C 2 H 5 . O . NO, is a mobile, yellowish liquid, of specific gravity 0.947, at 15, and boils at -4-l6. It is insoluble in water, and possesses an odor resembling that of apples. It is obtained by the action of sulphuric acid and potassium nitrite upon alcohol (A. 253, 251 Anm.}. It is the active ingre- dient of Spiritus cetheris nitrosi. When ethyl nitrite stands with water it gradually decomposes, nitrogen oxide being eliminated ; an explosion may occur under some conditions. Hydrogen sulphide changes it into alcohol and ammonia. Normal Butyl Nitrite, C 4 H 9 . O . NO, boils at 75, the secondary at 68, and the tertiary, C(CH 3 ) 3 . O . NO, at 77. Isoamyl Nitrite, C 5 H n . O . NO, obtained by the distillation of fermentation amyl alcohol with nitric acid, is a yellow liquid boiling at 96 ; its specific gravity is o. 902. An explosion takes place when the vapors are heated to 250. Nascent hydrogen changes it into amyl alcohol and ammonia. Heated with methyl alcohol, it is transformed into methyl nitrite and amyl alcohol. The result is the same if ethyl alcohol be used (B. 20, 656). Amyl nitrite, " Amylium nitrosum" is used in medicine, and also for the prepara- tion of nitroso- and diazo-compounds. , C 2 H 5 O . N = N O . C 2 H 5 , results from the interaction of ethyl iodide and nitrosyl silver (NOAg) 2 . It is the ester of hyponitrous acid (B. ix, 1630). D. ESTERS OF SULPHURIC ACID. (l) The neutral esters are formed by the action of the alkyl iodides upon silver sulphate, SO 4 Ag 2 ; they are also produced, in slight quantity, on heating the primary esters or alcohols with sulphuric acid. They can be extracted with chloroform from the product, and are heavy liquids, soluble in ether, possess an odor like that of pep- permint, and boil without decomposition. They will sink in water, and gradually decompose into a primary ester and alcohol : ESTERS OF SULPHURIC ACID. 145 " 5 cH. OH. The Dimethyl Ester, SO 2 (O . CH 3 ) 2 , boils at 188. The diethyl ester, SO 2 (O.C 2 H 5 ) 2 , boils at 208. It is formed also from SO 3 and (C 2 H 5 ) 2 O, and when heated with alco- hol, ethyl sulphuric acid and ethyl ether are produced (B. 13, 1699 ; 15, 947). (2) The primary esters or ether-acids are produced (i) when the alcohols are mixed with concentrated sulphuric acid: S0 2 (OH) 2 + C 2 H 5 . OH = S0 2 < R C ' H 5 -f H 2 0. The reaction takes place only when aided by heat, and it is not complete, because the mixture always contains free sulphuric acid and alcohol (compare p. 137). The reaction does proceed to completion if the alcohol be dissolved in very little sulphuric acid, and SO 3 in the form of fuming sulphuric acid be then allowed to act upon the well-cooled solution (B. 28, R. 31). To isolate the ether-acids, the product of the reac- tion is diluted with water and boiled with an excess of barium carbonate. In this way the unaffected sulphuric acid is thrown out as barium sulphate ; the barium salts of the ether-acids are soluble and crystallize out when the solution is evaporated. To obtain the acids in a free state their salts are treated with sulphuric acid or the lead salts (obtained by saturating the acids with lead carbonate) may be decomposed by hydrogen sulphide, and the solution allowed to evaporate over sulphuric acid. Even secondary alcohols, by careful cooling of the components, are capable of forming ether sulphuric acids e. g., ethyl propyl carbinol (B. 26, 1203). (2) The ether cuids also result from the union of the alkylens with concentrated sulphuric acid. Properties. These acids are thick liquids, which cannot be distilled. They sometimes crystallize. They dissolve readily in water and alcohol, but are insoluble in ether. (1) When boiled or warmed with water they break down into sul- phuric acid and alcohol : S0 2 < H C A + H 2 = S0 4 H 2 -f C 2 H 5 . OH. (2) When distilled, they yield sulphuric acid and alkylens (p. 92). (3) Upcm heating them with alcohols, simple and mixed ethers (p. 133) are produced. They show a strongly acid reaction, and furnish salts which dissolve quite readily in water, and crystallize without great trouble. The salts gradually change to sulphates and alcohol when they are boiled with water. Those with the alkalies are frequently applied in different reac- tions. Thus with KSH and K 2 S they yield mercaptans and thio-ethers (p. 149); with salts of fatty acids they furnish esters, and with KCN the alkyl cyanides, etc. Methyl Sulphuric Acid, SO 4 (CH 3 )H, is a thick oil. Ethyl Sulphuric Acid, SO 4 (C 2 H 5 )H, is obtained by mixing I part alcohol with 2 parts concentrated sulphuric acid. The potassium salt, SO 4 (C 2 H 5 )K, is anhydrous ; it crystallizes in plates. The barium and calcium salts crystallize in large tablets with two molecules of H 2 O each (A. 218, 300). The chlorides or chloranhydrides of the ether sulphuric acids ( SO 2 <2 ,' 2 5 V 146 ORGANIC CHEMISTRY. called esters of chlorsulphonic acids, result in (i) the action of sulphuryl chloride upon the alcohols : C 2 H 5 . OH + SO 2 C1 2 = SO 2 <^j- C 2 H5 + HC1 ; Chloride of Ethyl Sulphuric Acid. (2) by the action of PC1 5 upon salts of the ether acids ; (3) by the union of the olefines with Cl. SO 3 H; (4) by the union of SO 3 with the alkyl chlorides; and (5) by the action of SO 2 upon the esters of hypochlorous acid (B. 19, 860) : S0 2 + CIO . C 2 H 5 = S0 2 < All are liquids with penetrating odor. Cold water decomposes them very slowly, with the formation of the ether acids. These they yield, together with ethyl chlorides, on adding alcohol to them. The reaction is rather energetic. Chloride of Ethyl Sulphuric Acid, C 2 H 5 . O . SO 2 C1, boils at about 152. Methyl Sulphuric Chloride, CH 3 . O . SO 2 C1, boils at 132. i E. ESTERS OF SYMMETRICAL SULPHUROUS ACID. The empirical formula of sulphurous acid, SO 3 H 2 , may have one of two possible structures : SO ^ . C 2 H 5 I are not isomeric, in which case a difference of the 4 valences of S would be proven, but identical (B. 22, R. 648). The sulphonium hydroxides are crystalline, efflorescent, strongly basic bodies, readily soluble in water. Like the alkalies, they precipitate metallic hydroxides from metallic salts, set ammonia free from ammoniacal salts, absorb CO 2 and saturate acids, with the formation of neutral salts : (C 2 H 5 ) 3 S . OH + N0 3 H = (C 2 H 5 ) 3 S . NO, + H 2 O. We thus observe that relations similar to those noted with the nitrogen group pre- vail with sulphur (also with selenium and tellurium). Nitrogen and phosphorus combine with four hydrogen atoms (also with alcoholic radicals) to form the groups ammonium, NH 4 , and phosphonium, PH 4 , which yield compounds similar to those of the alkali metals. Sulphur and its analogues combine in like manner with three univalent alkyls, and give sulphonium and sulphine derivatives. Other -non-metals and the less positive metals, like lead and tin, exhibit a perfectly similar behavior. By addition of hydrogen or alkyls they acquire a strongly basic, metallic character (see the metallo-organic compounds and also the aromatic iodonium bases). Trimethyl Sulphonium Iodide, (CH 3 ) 3 SI, is readily soluble in water, soluble with difficulty in alcohol, and crystallizes from the latter in white needles. At 215 it breaks down quietly into methyl sulphide and methyl iodide. Platinic chloride pre- cipitates, from solutions of its chloride, a chloroplatinate, [(CH,) 3 SC1] 2 . PtCl 4 , very similar to ammonium platinum chloride. Trimethyl Sulphonium Hydroxide, (CH 3 ) 3 SOH, consists of deliquescent crystals with a strongly alkaline reaction. Consult B. 24, R. 906, upon the refractive power and the lowering of the freezing point of sulphine compounds. E. Sulphoxides and Sulphones, as mentioned (p. 149), result from the oxidation of the sulphides with nitric acid : ^"C - 2 . 2 . , 5 Ethyl Sulphide. Ethyl Sulphoxide. Ethyl Sulphone. The stilpkoxides may be compared to the ketones. Nascent hydrogen reduces them to sulphides. Methyl- and Ethyl Sulphoxides are thick oils, which combine with nitric acid: (CH 3 ) 2 SO . NO 3 H. Barium carbonate will liberate the Sulphoxides from these salts. Methyl Sulphoxide is also formed when silver oxide acts upon methyl sulph-bromide, (CH 3 ) 2 SBr 2 . The sulphones, obtained from the Sulphoxides by means of nitric acid, or by oxida- tion with potassium permanganate, may also be regarded as esters of the alkyl sul- phinic acids (see these), because they can be prepared from salts of the latter through the action of atkyl iodides : C 2 H 5 . S0 2 K + C 2 H 5 I = 25 >S0 2 + KI. However, they are not true esters, but remarkable compounds, characterized by great stability, in which both alcohol radicals are linked to sulphur. They cannot be reduced to sulphides. Methyl Sulphone, (CH 3 ) 2 SO 2 , melts at 109 and boils at 238. Ethyl Sulphone, (C 2 H 5 ) 2 SO 2 , melts at 70 and boils at 248. 152 ORGANIC CHEMISTRY. ALKYL SULPHONIC ACIDS, ALKYL THIOSULPHURIC ACIDS, ALKYL THIOSULPHONIC ACIDS, AND ALKYL SULPHINIC ACIDS. These compounds have the general formulas : R'. S0 2 OH R'S . S0 3 H R'. SO 2 SH R'. SO 2 H C 2 H 5 .S0 2 OH C 2 H 5 S.S0 3 H C 2 H 5 . SO 2 SH C 2 H 5 . SO 2 H Ethyl Sulphonic Ethyl Thiosulphuric Ethyl Thiosulphonic Ethyl Sulphinic Acid. Acid. Acid. Acid. F. Sulphonic Acids. The sulpho-acids or sulphonic acids contain the sulpha-group SO 2 . OH, joined to carbon. This is evident from their production by the oxidation of the mercaptans, and from their re-conversion into mercaptans (p. 148). They can be viewed as ester derivatives of the unsymmetrical sulphurous acid, HSO 2 OH (p. 146). Formation, (l) Their salts result from the interaction of alkaline sulphites and alkyl iodides ; their esters are formed when alkyl iodides act upon silver sulphite : K . SO 2 . OK -f C 2 H 5 I = C 2 H 5 . SO 2 OK + KI Potassium Ethyl Sulphonate. Ag . SO 2 . OAg + 2C 2 H 5 I = C 2 H 5 . SO 2 . . C 2 H 5 + 2 Agl. Ethyl Sulphonic Ethyl Ester. (2) By oxidation of (a) the mercaptans ; (b) the alkyl disulphides ; (c) the alkyl thiocyanates with nitric acid : (3) The alkyl sulphinic" acids are readily oxidized to sulphonic acids. (4) The sulpho-acids can be formed further by the action of sulphuric acid or sulphur trioxide upon alcohols, ethers, and various other bodies. This reaction is very common with benzene derivatives and proceeds without difficulty. Properties and Transpositions. These acids are thick liquids, readily soluble in water, and generally crystallizable. They suffer decomposition when exposed to heat, but are not altered when boiled with alkaline hydroxides. When fused with solid alkalies they break up into sulphites and alcohols : C 2 H 5 . SO 2 . OK -f KOH = KSO 2 . OK -f C 2 H 5 . OH. PC1 5 changes them to chlorides, e. g. y C 2 H 5 . SO 2 C1, which become mercaptans through the agency of hydrogen, or by the action of sodium alcoholates pass into the neutral esters C 2 H 5 . SO 3 . C 2 H 5 (p. 146). Many of these reactions plainly indicate that in the sulphonic acids the sulphur is directly combined with the alkyls, and that very probably, therefore, in the sulphites the one metallic atom is directly united to sulphur. The sulphonic esters boil con- siderably higher than the esters of symmetrical sulphurous acid (p. 146). Alkalies convert the latter into sulphites and alcohol, whereas in the sulphonic esters only one alkyl group that not directly linked to sulphur is removed. Methyl Sulphonic Acid, CH 3 . SO 3 H, was synthetically prepared by Kolbe in 1845 frm carbon disulphide. Chlorine converted the latter into trichlormethyl sulphonic chloride, which was changed to the corresponding acid, and the latter reduced by sodium amalgam to methyl sulphonic acid, just as acetic acid is obtained from trichlor-acetic acid (see this) (A. 54, 174) : C + 2S = CS 2 -- ^CC1 3 .SO 2 C1- ^CC1 3 .SO 3 H- -^CH 3 .SO 3 H. Trichlormethyl sulphonic acid will be discussed later, after carbonic acid. Barium Salt, (CH 3 . SO 3 ) 2 Ba + ^H 2 O. Methyl Sulpha-chloride > CH 3 . SO 2 C1, boils at 1 60. SULPHUR DERIVATIVES OF THE ALCOHOL RADICALS. 153 Ethyl Sulphonic Acid, C 2 H 5 . SO 3 H, is oxidized by concentrated nitric acid to ethyl sulphuric acid, C 2 H 5 O . SO 3 H (p. 144). Its lead salt, (C a H 5 . SO 3 ) 2 Pb, is readily soluble. Its chloride, C 2 H- . SO 2 C1, boils at 177. Its methyl ester, C 2 H 5 SO 3 CH 3 , boils at 198. Its ethyl ester, C 2 H 5 . SO 3 . C 2 H 5 , boils at 213.4. G. Alkyl Thiosulphuric Acids. I. The well-crystallized alkali salts of these acids are made by acting upon alka- line hyposulphites with primary saturated alkyl iodides (B. 7, 646, 1157) or alkyl bromides (B. 26, 996) : C 2 H 5 I + NaS . SO 3 Na = C 2 H 5 S . SO 3 Na + Nal. Sodium ethyl thiosulphate is called Bunte's salt, after its discoverer. (2) It also results when iodine acts upon a mixture of sodium mercaptide and sodium sulphite : C a H 5 SNa + NaS0 8 Na + I, = C 2 H 5 S. SO 3 Na + 2NaI. The free acids are not stable. Mineral acids convert sodium ethyl thiosulphate into mercaptan and primary sodium sulphate. Heat breaks down the salts into disulphides, neutral potassium sulphate, and sulphur dioxide. H. The Alkyl Thiosulphonic Acids. These acids are only stable in salts and esters. They are formed by the action of the chlorides of sujpho- acids upon potassium sulphide : C 2 H 5 . SO 2 C1 -|- K 2 S = KC1 -(- C 2 H 3 . SO 2 . SK. The esters, R . SO 2 SR, of this new class were formerly called alkyl disulphoxides, R 2 S 2 O 2 , and are obtained (l) from the alkali salts by the action of the alkyl bromides ( B. 15, 123) : C 2 H 5 . SO 2 . SK + C 2 H 5 -Br = C 2 H 5 . SO 2 . SC 2 H- -f KBr; and (2) by the oxidation of mercaptans and alkyl disulphides with dilute nitric acid : (C 2 H 5 ) 2 S 2 -f O 2 = C 2 H 5 . SO 2 . SC 2 H 5 . These esters are liquids, insoluble in water, and possessed of a disgusting onion-like odor (B. 19, 1241, 3131). Ethyl Thiosulphuric Ethyl Ester, C 2 H. . SO, . S . C 2 H., boils at 130- 140. I. Esters of Hydrosulphurous Acid Sulphinic Acids. Two structural IV jj VI formulas are possible for hydrosulphurous acid: H . SO . OH and ^>SO 2 . Re- IV place one hydrogen atom and the sulphinic acids result, e. g., (l) C 2 H 3 . SO . OH or The true alkyl sulphinic esters are derived from the first formula. The sulphones can be referred to the second formula (p. 151). The sulphinates are produced as follows : (1) By the oxidation of the dry sodium mercaptides in the air. (2) When SO 2 acts upon the zinc alkyls, the sulphinic acids (their zinc salts) result. (3) When zinc acts upon the chlorides of the sulphonic acids : ( i ) C 2 H 5 SNa + 2O = C 2 H 5 SO 2 Na (2) (C 2 H 5 ) 2 Zn + 2S0 2 = [C 2 H 5 S0 2 ] 2 Zn (3) 2CjH.SO.jCl -f 2Zn = [C 2 H 5 SO 2 ] 2 Zn -f ZnCl 2 . The sulphones (p. 151) are produced in the action of alkyl iodides upon the alkaline sulphonates, while the real esters result from the etherification of the acids with alcohol and hydrochloric acid, or by the action of chlorcarbonic esters upon the sulphinates (B. 18, 2493) : R - SO 2 Na -f Cl . CO 2 R = R . SO . OR -f- CO 2 -f NaCl. When these esters are saponified by alcohol or water they break down into alcohol and sulphinic acid, while the isomeric sulphones are not altered. The free sulphinic acids are liquids ; not very stable ; they rapidly oxidize to sulphonic acids. Potassium permanganate and acetic acid convert the sulphinic esters into sulphonic esters (B. 19, 1225), whereas the isomeric sulphones remain unchanged. 154 ORGANIC CHEMISTRY. 4. SELENIUM AND TELLURIUM COMPOUNDS. These are perfectly analogous to the sulphur compounds. Ethyl Hydroselenide, C 2 H 5 .SeH, is a colorless, unpleasant-smelling, very mobile liquid. It combines readily with mercuric oxide to form a mercaptide. Ethyl Selenide, (C 2 H.) 2 Se, is a heavy, yellow oil, boiling at 108. It unites directly with the halogens, e. g., (C 2 H 5 ) 2 SeCl 2 . It dissolves in nitric acid with for- mation of the oxide, (C 2 H 5 ) 2 SeO, which yields the salt, (C 2 H 5 ) 2 Se(NO 8 V Tellurium mercaptans are not known. Methyl Telluride, (CH 3 ) 2 Te, boils at 80-82, and Ethyl Telluride, (C 2 H 5 ) 2 Te, boils 31137.5. They are obtained by distilling barium alkyl sulphate with potassium telluride. They are heavy, yellow oils. The following compounds are derived from them: (CH 3 ) 2 Te(NO 3 ) 2 , (CH 3 ) 2 - TeCl ? , (CH 3 ) 2 TeO, (CH 3 ) 3 TeI, (CH 3 ) 3 Te. OH, etc. Dimethyl Tellurium Oxide, (CH 3 ) 2 TeO, is a crystalline efflorescent compound. In properties it resembles CaO and PbO. It reacts strongly alkaline, expels ammonia from ammonium salts, and forms salts by neutralizing acids. 5. NITROGEN DERIVATIVES OF THE ALCOHOL RADICALS. A. MONONITRO-PARAFFINS AND OLEFINES, HALOGEN MONONITRO- PARAFFINS. By nitro-bodies are understood compounds of carbon in which the hydrogen combined with the latter is replaced by the univalent nitro- group, NO 2 . The carbon is directly united to the nitrogen, as the reduction of the nitro-derivatives yields amido-compounds : R'. NO, + 6H = R'. NH 2 + 2 H 2 O. In the aromatic series the hydrogen atoms of the benzene nucleus are readily replaced by nitre-groups, e.g. : C 6 H 6 -f N0 2 OH = CeH^NO, + H 2 O. Nitrobenzene. Comparative refractometric investigations have shown that the nitro-group in nitroethane, and that in nitrobenzene, do not have the same structure (Z. ph. Ch. 6, 552; compare p. 156). See B. 28, R. 153, upon the heat of combustion of the nitro-paramns. (1) Fatty bodies can only be 'directly nitrated under certain con- ditions. This is particularly true when the substance contains a tertiary carbon atom, e. g., CHC1 3 , chloroform, or isovaleric acid, (CH 3 > 2 CH . CH 2 . CO 2 H, etc. Normal hexane, normal octane, and paraffins richer in carbon have been nitrated by merely heating them to 130-140 with dilute nitric acid (Konowalow, B. 26, R. 108; B. 28, 1863). (2) A common method for the preparation of the mononitro- derivatives of fatty hydrocarbons the nitroethanes consists in heating the iodides of the alcohol radicals with silver nitrite ( V. Meyer, 1872) (A. 171, i; 175, 88; 180, in): C 2 H 5 I + AgN0 2 == C 2 H 5 . N0 2 + Agl. NITROGEN DERIVATIVES OF THE ALCOHOL RADICALS. 155 The isomeric esters of nitrous acid, such as C 2 H 5 . O . NO, arise (B. 15, 1547) in this reaction. From this we would infer that silver nitrite conducted itself as if appar- ently consisting of AgNO 2 and Ag.O.NO. (Potassium nitrite does not act like AgNO 2 .) Since, however, CH 3 I only yields nitromethane, and the higher alkyl- iodides decompose more readily into alkylens, the greater the quantity of nitrous acid esters, it would appear that the formation of esters is influenced by the production of alkylens, which afterward form esters by the union with HNO 2 (A. 180, 157, and B. 9, 529). Possibly the alkylogens add themselves directly to the nitiogen, or in consequence of an opening-up of the double N = O union. (3) Simultaneously with the discovery of method 2, Kolbe demonstrated that nitromethane resulted from the action of potassium nitrite upon chlor-acetic acid. The first product in this instance was nitro- acetic acid, which broke down into carbon dioxide and nitromethane (J. pr. Ch. [2] 5, 427) : CH 2 C1 . CO a H - > [CH 2 (NO 2 ) . CO 2 H] - > CH 3 NO 2 -f CO 2 . (4) By a nucleus-synthesis : Zinc alkyls, acting upon chlor- and brom-nitro- paraffins, produce mononitro-paraffins (B. 26, 129) : Zn(CH 3 ) 2 " CH 3 . CH(NO 2 ) . CH 3 , Secondary Nitropropane. Zn(CH 3 ) 2 > C . NO 2 (CH 3 ) 3 , Tertiary Nitrobutane. Properties and Transpositions of the Nitro-paraffins . The nitro- paraffins are colorless, agreeably-smelling liquids, which are sparingly soluble in water. They distil without decomposition, and only explode with difficulty. Their boiling points lie considerably higher than those of the corresponding nitrous esters (p. 144). (i) Caustic potash and soda do not decompose the nitro-paraffins. They readily break down the isomeric nitrous esters (p. 144) into nitrous acid and alcohol. It is remarkable that the nitro-paraffins deport themselves like acids, thus differing from the halogen substitu- tion products. An atom of hydrogen in them can be replaced by the action of caustic alkalies: CH 3 . CH 2 (NO 2 ) -f KOH = CH 3 .-CHK(NO 2 ) -f H 2 O. The nitro-group always exerts such an acidifying influence upon the hydrogen in union with carbon. It is further increased by the entrance of halogen atoms or nitro- groups, but limits itself to the hydrogen atom united with the carbon atom carrying the nitro-group. Thus the compounds: CH 3 . CHBr(NO 2 ), brom-nitroethane, CH 3 . CH(NO 2 ) 2 , di-nitroethane, CH(NO 2 ) 3 , nitroform, etc., are strong acids, while CH 3 . CBr 2 (NO 2 ) and (CH 3 ). 2 C(NO 2 ) 2 , /3-dinitro-propane, etc., possess neutral reaction and do not combine with bases. The acid properties diminish with increasing molecular weight. From aqueous solutions of the alkali salts, salts of heavy metals precipitate metallic compounds, which, as a rule, explode with great violence. Nef assumes in the metal derivatives of the nitro-paraffins that the metal is com- bined with oxygen, e.g.: /0-Xa CH,.CH = NC because they are resolved by acids into aldehydes or ketones and nitrous oxide. \\hen carefully treated with acids, the nitro-paraffins can, in part, be regained from 156 ORGANIC CHEMISTRY. their metallic derivatives. It might be assumed, therefore, that the unstable (labile) x^O bodies of the formula RCH : N\ when liberated from their salts pass over into ^OH the more stable variety R . CH 2 . NO 2 . The deportment of phenyl nitromethane renders this view probable ; it occurs in the two isomeric modifications, C 6 H 5 CH 2 NO 2 and C 6 TI 5 CH : N^f (B. 29, 1223). ^OU (2) By gradual reduction the nitro-bodies (V. Meyer, B. 24, 3528, 4243 ; 25, 1714) pass first into alkyl hydroxylamines (p. 172) and then into primary amines: -^CH 3 .NH.OH Nitromethane. Methyl Hydroxylamine. Methylamine. The conversion of nitro-paraffins into primary amines proves, as indicated before, that the nitrogen of the nitro-group present in them is linked to carbon. For nitro- methane we have the choice between the following formulas (compare B. 29, 2263) : /OH CH 2 -NOH. CHj-NO,, CH 2 = N^ , \6 X O (3) The varying deportment of the nitro-paraffins with nitrous acid (better NO 2 K and H 2 SO 4 ) is very interesting, according as the nitro-group is linked to primary, secondary, or tertiary radicals. On mixing the primary nitro-compounds with a solution of NO 2 K in concentrated potassium hydroxide and adding dilute H 2 SO 4 , the solution assumes in the beginning an intense red color due to a soluble, red-colored alkali salt of a nitrolic acid. The nitro-compounds of the secondary radicals, when subjected to similar treat- ment, yield a dark blue coloration, due to a so-called pseudo-nitrol : CH 3 * * Ethyl Nitrolic Acid (Nitro-acetoxime). (CH 3 ) 2 CHN0 2 + NOOH = Propyl Pseudonitrol. The nitro-compounds of tertiary radicals do not react with nitrous acid. There- fore, the preceding reactions serve as a very delicate and characteristic means of distinguishing primary, secondary, and tertiary alcoholic radicals (in their iodides), from one another. (4) Chlorine and bromine, acting upon the alkali salts of primary and secondary nitro-paraffins, produce chlor- and brom-nitro-substitution products. In them the halogen atom is joined to the same carbon atom as the nitro-group. For compounds resulting from the action of sodium ethylate and the alkyl iodides upon the nitro-ethanes, see B. 21, R. 58 and 710. Zinc ethide converts nitroethane into triethylamine oxide (B. 22, R. 250). Primary Mono-nitro-paraffins : Nitromethane, CH 3 NO 2 , boils at IOI. It is isomeric with formhydroxamic acid. Sodium and potassium nitromethane explode with great violence when they are heated. This also occurs when these substances, dried in a desiccator, come in contact with traces of water (B. 27, 3406). When corrosive sublimate acts upon sodium nitromethane, fulminating mercury is produced (see this). By the action of caustic potash upon nitromethane or of hydroxylamine hydrochloride upon sodium nitromethane, Methazonic Acid, C 2 H 4 N 2 O 3 , is formed. It is a monobasic acid of unknown constitution (B. 29, 2288), and melts at 79. NITROGEN DERIVATIVES OF THE ALCOHOL RADICALS. 157 Nitroithane, CII 3 .CH 2 NO 2 , boils at 113-114; aNitropropane, CH 3 .CH 2 .- CH 2 NO. 2 , boils at 130-131 ; Nitro-normal butane, CH 3 . CH 2 . CH 2 . CH 2 NO 2 , boils at 151; Nilro-isobutane, (CH 3 ) 2 CH . CH 2 NO 2 , boils at 137-140; Nitro-normal octane, CH 3 . [CH 2 ] 6 . CH 2 . NO,, boils at 205-212. Secondary Mono-nitro-paraffins : honitropropane, (CH 3 ) 2 CHNO 2 , boils at 117- ^ boils at 138. Tertiary Mono-nitro-paraffins : Tertiary Nitrobutanc, (CH 3 ) 3 C . NO 2 , boils at 126. Halogen Nitro-compoiinds : Chlor-nitromethane, CH 2 C1(NO 2 ), boils at 122; Brom-nitro-methane, CH 2 Br(NO 2 ), boils at 146 (B. 29, 1823) ; Brom-nitro-ethane, CH 3 . CHBr(NO 2 ), boils at 146-147; a-brom-nitropropane, CH 3 . CH 2 . CHBr(NO 2 ), boils at 160-165. All of these bodies are acids. The hydrogen of the CHC1(NO 2 ) or CHBr(N() 2 ) group is replaceable by the alkali metals. Systematically considered, these derivatives belong to the aldehydes. It is only because of their genetic relations that they are described at the conclusion of the mono-nitro-paraffins. Thus, fi-brom-fi-nitrupropane, (CH 3 ) 2 CBrNO 2 , boiling at 148-150, belongs after acetone, while dibrom-nitromethane, CHBr 2 (NO 2 ) (B. 29, 1824), dibrom-nitroethane, CH 3 CBr. 2 (XO 2 ), boiling at 165, zn&dibrom-nitropropane, boiling at 185, should follow formic acid, acetic acid, and propionic acid. Nitro- chloroform or chlorpicrin, CC1 3 NO 2 , and nitrobromofortn, or brompicrin, CBr 3 NO 2 , will be discussed after CC1 4 , CBr 4 , CI 4 , together with carbonic acid. The halogen atoms in the chlor- and brom-nitro-paraffins can be replaced by alcohol radicals" through the action of zinc alkyls. Thus, higher homologous mono-nitro-paraffins can be prepared by nucleus-syntheses (p. 155). Nitropropylene, CH 2 = CH. CH 2 NO 2 , from the action of allyl bromide or iodide upon silver nitrite, is a thick, brownish oil. It cannot be distilled without decom- position even under much diminished pressure. In every other respect it manifests the characteristic behavior of a primary nitro-body (B. 25, 1701). NOTE. Nitrolic Acids and Pseudonitrols. These two classes of derivatives will be treated at this point, although the nitrolic acids belong after the mono-carboxylic acids, into which they readily pass, as well as the imido-amides or amidines and the amidoximes : /OH /NH 2 /NO 2 /NH 2 Acetic Acid. Acetamidine. Ethyl-nitrolic Acid. Ethenyl Amidoxime. Systematically considered, the pseudonitrols should follow the ketones. They arise from their oximes, and are probably to be regarded as their nitric acid esters : (CH 3 ) 2 CO (CH 3 ) 2 C<' (CH 3 ) 2 C = N.ON0 2 (CH 3 ) 2 C = Acetone. < ---- , ---- / Acetoxime. Propyl Pseudonitrol. Nitrolic Acids. They are produced (i) by the action of nascent nitrous acid upon the primary nitro -paraffins. (2) By treating the dibrom-nitro-paraffins with hydroxyl- amine : /NO, CH 3 . CBr 2 (N0 2 ) + H 2 N . OH = CH 3 . C (CH 3 ) 2 C = N . OH. NO Propyl Pseudonitrol, (CH 3 ) 2 CC -f KBr. (3) By the action of concentrated nitric acid upon ( CH 3 . CH 2 . CH(NO 2 ) 2 (C 2 H 5 ) 2 CO > CH 3 . CH 2 . CH(N0 2 ) 2 3 . 2 CH 3 CO.CH(C 2 H 5 )CO 2 C 2 H 5 -- > CH 3 .CH 2 . CH(NO 2 ) 2 + CH 3 . CO 2 H+CO 2 . (4) By the oxidation of saturated mono-carboxylic acids, containing a tertiary carbon atom, with nitric acid : isobutyric and isovaleric acids yield meso-dinitro- propane : (CH 3 ) 2 CHC0 2 H (CH 3 ) 2 CH . CH 2 . CO 2 H > (CH 3 ) 2 C(NO 2 ) 2 . The primary dinitro-bodies are acids. The primary and secondary classes split off hydroxylamine when they are reduced with tin and hydrochloric acid. The former yield, at the same time, mono-carboxylic acids, and the latter ketones. This deportment led to the consideration of the following structural formulas for the two classes of dinitro-derivatives (B. 23, 3494) : OH v y O.NO 2 for CH 3 .CH(NO 2 ) 2 ; (CH 3 ) 2 C=:N\\s at 212. 2,2-Dinitro- propane, CH 3 . C(NO 2 ) 2 . CH 3 , melts at53 and boils at 185.5. 2,2-Dinitrobutane, CH 3 . CH 2 . C(NU 2 ) 2 . CH 3 , boils at 199. Higher homologues, see B. 29, 95. The onlyw-, G/-, or i,-$-Dinitropropane, NO 2 CH 2 . CH 2 . CH 2 NO 2 , having the two nitro- groups attached to different carbon atoms, is an unstable oil obtained by the action of AgNO 2 upon trimethylene iodide (B. 25, 2638). Of the poly-nitro-derivatives of methane there remain nitroform, CH(NO 2 ) 3 . to be considered after chloroform, bromoform, and iodoform in connection with formic acid, bromnitroform, C(NO 2 ) 3 Br, and tetranitromethane, C(NO 2 ) i , which will come up for consideration under carbonic acid, following chlorpicrin and brompicrin. B. ALKYLAMINES AND ALKYL AMMONIUM DERIVATIVES. Alkylamines are those bodies which result from the introduction of univalent alkyls into ammonia for its hydrogen. One, two, and three hydrogen atoms of the ammonia molecule may l6o ORGANIC CHEMISTRY. suffer this replacement, thus yielding the primary, secondary, and tertiary amines : \H \H \H 3 \C 2 Hj \CH 3 5 Ethylamine. Diethylamine. Methyl Triethylamine. Methyl-ethyl- Ethylamine. propylamine. These are also sometimes called amide, imide, and nitrile bases. Under the imide and nitrile bases, the secondary and tertiary amines, we distinguished simple amines, those with similar alcohol radicals, and mixed amines, those containing different alcohol radicals; com- pare simple and mixed ethers (p. 132). Derivatives also exist which correspond to the ammonium salts and hypothetical ammonium hydroxide, NH 4 OH : (C 2 H 5 ) 4 NC1 (C 2 H 5 ) 4 N.OH Tetraethyl Ammonium Chloride. Tetraethyl Ammonium Hydroxide. These are the quaternary alkyl ammonium compounds. Isomerism of the Alkylamines. The isomerism of the simple alkyl- amines depends upon the homology of the alcohol radicals, metamerism; and in the higher alkylamines, in addition, upon the different position of the nitrogen in the same carbon chain, isomerism of position ; and also upon the different manner of linkage of the carbon atoms of the isomeric alkyl residues, nucleus isomerism (p. 41). There are seven isomerides of C 4 H n N : c 4 H 9 rc 3 H 7 rc 2 H 3 H NJCH 3 *HCH 3 H IH (cH 3 4-Isomeric Butyl- 2-Isomeric Propyl- Ethyl-dimethyl amines. methylamines. Amine. History. The existence of alkylamines, or alcohol bases, was very definitely pre- dicted by Liebig in 1842 (Hdw. i, 689). In 1849 Wurtz discovered a method for the preparation of primary amines. It consisted in decomposing isocyanic ether with caustic potash. This was a discovery of the greatest importance for the devel- opment of organic chemistry. Shortly after, in 1849, A. W. Hofmann, by the action of alkylogens on ammonia, discovered a reaction which made possible the preparation of all the classes described in the preceding paragraphs: primary, secon- dary, tertiary amines, and the alkyl ammonium bases. This afforded the experimental basis for the introduction of the ammonia type\n\.o organic chemistry (compare p. 35). Since that time numerous other methods of preparation have been found, particularly for the primary amines. The following general methods are the most important for preparing the above compounds: (i a) The iodides, the bromides, or the chlorides of the alcohol radicals are heated to 100, in sealed tubes, with alcoholic ammonia (A. W. Hofmann, 1849). Two reactions occur here : first, the alkyl- ogens combine with the ammonia, forming alkyl ammonium salts, which then are partially decomposed by excess of ammonia, with the ALKVLAMINES AND ALKYL AMMONIUM DERIVATIVES. l6l production of alkylamines, to which alkylogens again unite them- selves e. g. : C 2 H 3 I = NH 2 (C 2 H 5 )HI NH 2 C 2 H 5 + C 2 H 5 I = NH(C 2 H 5 ) 2 HI *-> NH(C 2 H 3 ) 2 + NH 4 I NH(C 2 H 5 ) 2 -fC 2 H 5 I = N(C 2 H 5 ) 3 HI ^ N(C 2 H 5 ) 3 + NH 4 I N(C 2 H 5 ) 3 + C 2 H 5 I = N(C 2 H 5 )J. The final product consists of the hydro-iodides of primary, secon- dary, and tertiary amines, and of the amide, imide, and nitrile bases, as well as the quaternary ammonium compounds. The amines are best obtained on a large scale by the action of ammonia upon the alkyl bromides (B. 22, 700). Potassium and sodium hydroxides decompose the salts of the am-ine, imide, and nitrile bases, with the splitting-off of the free bases, whereas the quaternary tetra-alkyl ammonium salts are not decomposed by caustic alkalies, and can thus be easily separated from t]ie primary, secondary, and tertiary amines (B. 20, 2224). It is remarkable that the primary and secondary (B. 22, R. 343) alkyl iodides yield at the same time secondary and tertiary amines, while the tertiary alkyl iodides do not form amines, but split off hydrogen iodide and pass into defines. (l b] The esters of nitric acid, when heated to IOO with alcoholic ammonia, react in a manner analogous to the alkyl iodides : C 2 H 5 . O . NO 2 -f NH 3 = C 2 H 5 . NH 2 -f HNO 3 . This reaction is often very convenient for the preparation of the primary amines (B. 14,421). ( I c) Tertiary amines are produced when primary and secondary bases are heated with an excess of potassium methyl sulphate (B. 24, 1678) : (C 2 H 3 ) 2 NH + CH 3 OS0 3 K = (C 2 H 5 ) 2 NCH 3 -f HOSO 3 K. (i d] Mono-, di-, and tri-alkylamines are obtained by directly heating the alcohols to 250-300 with zinc-ammonium chloride (B. 17, 640). (2) By action of nascent hydrogen (HC1 and Zn) upon the nitro- paraffins (p. 156), when the alkyl hydroxylamines appear as intermediate products, and upon the halo- gen mono-nitro-paraffins : CH S N0 2 -f 4H = CH 3 NHOH + H 2 O. CH, . NO 2 + 6H == CH 3 . NH 2 -f 2H 2 O. CC1 3 N0 2 + I2H = CH 3 NH 2 + 2 H 2 O + 3HC1. This method is particularly important in the manufacture of commercially valuable primary amines e. g., aniline from the readily accessible aromatic nitro-bodies. Zinin discovered the method when investigating the reduction of nitrobenzene, C 6 H-NO 2 . V. Meyer applied it to the aliphatic nitro-derivatives. (3 #) By the action of sodium in absolute alcohol upon the aldehyde-alkylimides (B. 29, 2110) ; (3 b] when zinc dust and hydrochloric acid are allowed to act upon aldehyde- ammonia derivatives (B. 27, R. 437) ; (3 c] from the phenylhydrazones (Tafel), and (3 d] the oximes (Goldschmidt) of the aldehydes and ketones by means 14 162 ORGANIC CHEMISTRY. of sodium amalgam and glacial acetic acid (B. 19, 1925, 3232; 20, 505 ; 22, 1854) : (CH 3 ) 2 CH . CH == N(CH 3 ) + 2 H = (CH 3 ) 2 CH . CH 2 . NHCH 3 (CH 3 ) . CH : N_NH . C 6 H 5 + 4H = CH 3 . CH 2 NH a + C 6 H 5 NH 2 (CH 3 ) 2 C : N-NH . C 6 H. + 4 H = (CH 3 ) 2 CHNH 2 + C 6 H 5 NH 2 (CH 3 ) 2 C : N_OH + 4H = (CH S ) 2 CHNH 2 -f- H 2 O. Reaction 3 a yields secondary amines, while 3 b, 3 c, and 3 d afford primary amines. (4) By the action of nascent hydrogen (from alcohol and sodium, B. 18, 2957; 19, 783; 22, 1854) upon the nitrites or alky 'I cyanides (Mendius, A. 121, 129) : HCN -f 4!! = CH 3 NH 2 ; CH 3 . CN -f- 4H = CH 3 . CH 2 . NH 2 . Methylamine. Acetonitrile. Ethylamine. The reaction constitutes an important intermediate factor both in the synthesis of alcohols (p. 113) and of amines. (5) Warm the isocyanides of the alkyls, the isonitriles, or carbylamines with dilute hydrochloric acid ; formic acid will split off (A. W. Hofmann] : C 2 H 5 . NC + 2H 2 O = C 2 H 5 . NH 2 + CH 2 O 2 . (6 a} The esters of isocyanic or fsocyanuric acid are distilled with potassium hydroxide (Wurtz, 1848): CO : N . CH 3 + 2KOH = NH 2 . CH 3 + CO 3 K 2 . Cyanic acid is changed to ammonia in precisely the same manner : CO : NH + 2KOH = NH 3 -f CO 3 K 2 . To convert alcohol radicals into corresponding amines, the iodides are heated together with silver cyanate ; the product of the reaction is then mixed with pulver- ized caustic soda, and distilled in an oil bath (B. 10, 131). (66) The isothiocyanic esters or the mustard oils, etc., are also broken down into primary amines by heating with water or dilute acids : CS : N . C 2 H 5 + 2H 2 = C0 2 -f H 2 S + C 2 H 5 NH 2 . (6 c] The isocyanic esters and the isothiocyanic esters or mustard oils are alkyl derivatives of the imide of carbonic acid, and thiocarbonic acid. The alkyl com- pounds of the imide of o-phthalic acid (see this) have shown themselves to be well adapted for the preparation of primary amines. They are readily prepared by acting upon potassium phthalimide with alkyl iodides. When heated with potassium hydroxide or acids, they separate into phthalic acid and primary amines (Gabriel, 20, 2224; 24, 3104): [i]co N CH ^' ' L ' 2 5 2KOH = (7) By the distillation of amin- or amido-acids, especially with baryta: CH 3 . CH< 2 = CHs C H 2 NH 2 -f CO 2 . Alanine. Ethylamine. ALKYLAM1NES AND ALKYL AMMONIUM DERIVATIVES. 163 (8) The splitting up of the secondary and tertiary aromatic p-nitroso-amines into salts of nitrosophenul (see this), by means of caustic potash, affords a means of preparing primary and secondary amines ; p-nitro-sod-dimethyl aniline yields dimethyl amine : NO[4]C 6 II 4 [i]X(CH 3 ) 2 + KOH = NH(CH 3 ) 2 + NO[ 4 ]C 6 H 4 [i]OK. (9) The conversion of the amides of the monocarboxylic acids, by means of caustic potash and bromine, into amines, containing an atom less of carbon (A. W. Hofmann, B. 18, 2734; 19, 1822). This reaction constitutes an intermediate step in the break-down of the saturated monocarboxylic acids, because the primary amines can be changed to alcohols, and the latter be oxidized to carboxylic acids, containing an atom less of carbon than the fatty acids, whose amides constituted the starting-out material. The reaction proceeds in two phases, the first of which is the forma- tion of the brom-amide of the fatty acid, and the second step the con- version of this new derivative into the primary amine : C 2 H 5 . CO . XH 2 + Br 2 + KOH = C 2 H 5 . CO . NHBr + KBr -f H 2 O C 2 H 5 . CO . NHBr -f jKOH = C 2 H 5 . NH 2 + CO 3 K 2 -f KBr + H 2 O. When I molecule of bromine and 2 molecules of the amide react, the product con- sists of mixed ureas ; thus acetamide yields methyl aceto-urea. The fatty-acid amides, with more than 5 C-atoms, not only yield amines, but also large quantities of the nitriles of the next lower acids : C 8 H 17 . CO . NH 2 yields C 7 H 15 . CN. (10) From acid-azides and alcohol. The corresponding acid is converted into an ester, the oxyethyl group is then replaced with (NH . NH 2 ) by means of hydrazine hydrate, the acid-azide, R . CO . NH . NH 2 , is changed by nitrous acid into the azide R . CO . N 3 , the latter is boiled with water or alcohol, and the resulting urea or urethane acted upon with concentrated hydrochloric acid, when the alkylized base splits off (Curtius, B. 27, 779; 29, 1166). R.CO.N, C2H5 H -^ R . NH . CO . ON 2 H 5 HC1 > R.NH 2 . Properties and Transpositions of the Amines. The amines are very similar to ammonia in their deportment. The lower members are gases, with ammoniacal odor, and are very readily soluble in water; their combustibility distinguishes them from ammonia. This was the property that attracted Wu'rtz to ethylamine (B. 20, R. 928). The higher members are liquids, readily soluble in water, and only the highest are sparingly soluble. Many amines possess the power of forming hydrates with water, accompanied by very considerable rise in temperature. They can be dried over potashes. Most of the oily hydrates contain a molecule of water for each nitrogen atom. This can only be removed by means of caustic potash (B. 27, R. 579), or by distillation over barium oxide. Like ammonia, they unite directly with acids to form salts, which differ from ammoniacal salts by their solubility in alcohol. They combine with some metallic chlorides, 164 ORGANIC CHEMISTRY. and form compounds perfectly analogous to the ammonium double salts; e.g. [N(CH 3 )H 3 C1] 2 RC1 4 . N(CH 3 )H 3 C1 . AuCl 3 . [N(CH 3 ) 3 HCl] 2 HgCl 2 . The ammonia in the alums, the cuprammonium salts and other compounds may be replaced by amines. Their basicity is greater than that of ammonia, and increases with the number of alkyls introduced (J. pr. Ch. [2] 33, 352). The reactivity of the primary and secondary amines, as compared with the tertiary amines, is dependent upon the ease with which the ammonia hydrogen atoms, not substituted by alcohol radicals, are replaced ; hence, the primary and the secondary amines in many reactions behave like ammonia. A primary amine is distinguished from a secondary amine, and this from a tertiary amine, by treating the amine alternately with methyl iodide and caustic potash until all the hydrogen atoms in the ammonia present are replaced by methyl groups. Whether the latter have entered, and what their number may be, is most conveniently deter- mined by the analysis of the platinum double chloride of the base previous to and after the action of the methyl iodide. It two methyl groups have entered, then the amine was primary ; if one methyl group has entered, then the base was secondary ; and should the base remain unchanged, then it is tertiary in its character. Tertiary, secondary, and primary amines may also be obtained by the dry distillation of the halogen salts of the ammonium bases : N(CH 3 ) 4 C1 =N(CH 3 ) 3 +CH 3 C1 N(CH 3 ) 3 HC1 = NH(CH 3 ) 2 + CH 3 C1 NH(CH 3 ) 2 HC1 = NH 2 (CH 3 ) -f CH 3 C1, etc. These reactions serve for the commercial production of methyl chloride from trimethylamine. Primary and secondary amines show the following reactions: (i) Primary and secondary amines, like ammonia, are transposed by acid esters, with the formation of mono- and di-alkylized acid amides (see these) and alcohols. A. W. Hofmann based a method for the separation of primary, secondary, and tertiary amines upon their deportment toward diethyl oxalate (B. 8, 760). The mixture of the dry bases is treated with diethyl oxalate, when the primary amine, e. g., methylamine, is changed to diethyl oxamide, which is soluble in water ; dimethylamine is converted into the ester of dimethyl oxamic acid (see oxalic acid compounds) ; and trimethylamine is not acted upon : (~\ C* TT 1\TT-T r^W 2NH 2 (CH 3 ) + C 2 2 < ' g = CA c MVP w \ Dithio-diethylamine. OV-'l Q il t l/ofTe jo SCI., ->- S SO 2 Pa 2 N(C 2 H 5 ) 2 'Diethylamine-chlorphosphine. , POCLN(C.H & ). Diethylamine-oxychlorphosphine. POC1 3 ' - PO[N(C 2 H 5 ) 2 ] 3 Tridiethylamine-phosphine-oxide. PSC1 3 - ?*- PSCI 2 N(C 2 H 5 ) 2 Diethylamine-sulphochlorphosphine. BCL --> BCl 2 NfC 2 H 5 ) 2 Diethylamine-chlorboride. SiCl 4 > SiCl 3 N(C 2 H 5 ) 2 Diethylamine-chlorsilicide. (2 ^) Primary and secondary amines are transposed like ammonia by organic acid chlorides e. g. } acetyl chloride into mono- and di- alkyl acid amides. (2 i) The primary and secondary amines deport themselves similarly with 2, 4-dinitrobrombenzene and picryl chloride or 2, 4, 6-trinitro- chlorbenzene (B. 18, R. 540). 1 66 ORGANIC CHEMISTRY. (3) Primary and secondary amines combine with many inorganic and organic acid anhydrides e. g., sulphur trioxide, acetic anhy- dride to form amic acids, and are then transposed into acid amides. (4) The deportment of. the amines toward nitrous acid is very char- acteristic. Primary amines are changed, at least in part, by this acid into their corresponding alcohols (p. 113) : C 2 H 5 NH 2 -f NO . OH = C 2 H 5 OH -f N 2 + H 2 O. This reaction corresponds to the decomposition of ammonium nitrite into water and nitrogen : NH 3 -f NO . OH = H 2 O -f N 2 + H 2 O. Frequently, instead of the expected secondary alcohols, those of the tertiary class are produced (B. 24, 3350). Nitrous acid converts the secondary amines into nitroso-amines (p. 170) : (CH 3 ) 2 NH -f NO . OH = (CH 3 ) 2 N . NO + H 2 O ; Nitroso-dimethylamine. whereas the tertiary amines remain unaltered or undergo decomposi- tions. Indeed, these reactions may be utilized in the separation of the amines, when naturally the primary amines are lost. (5) Another procedure, furnishing a partial separation of the amines, depends on their varying behavior toward carbon disulphide. The free bases (in aqueous, alco- holic, or ethereal solution) are digested with CS 2 , when the primary and secondary amines form salts of alkyl dithio-carbaminic acid (see this), while the tertiary amines remain unaffected, and may be distilled off. On boiling the residue with HgCl 2 or FeCl 3 , a part of the primary amine is expelled from the compound as mustard oil (A. VV. Hofmann, B. 8, 105, 461; 14, 2754; and 15, 1290). (6) A marked characteristic of the primary amines is their ability to form carbylamines (see these), which are easily recognized by their odor (A. W. Hofmann, B. 3, 767). (7) By the action of Cl, Br, or I alone or in the presence of caustic alkali, pri- mary and secondary amines yield alkylamine halides (p. 169). (8) The amines, when heated with potassium permanganate, are gradually oxidized to the corresponding aldehydes and acids, with the splitting-off of ammonia (B. 8, 1237)- (a} Amines and Ammonium Bases with Saturated Alcohol Radicals. (i) Primary Amines. Methylamine, CH 3 .NH 2 , occurs in Mercurialis perennis and annua, in bone-oil, and in the distillate from wood. It is produced from the methyl ester of isocyanic acid, by the reduction of chloropicrin, CC1 3 (NO 2 ), and hydrogen cyanide, and by the decomposition of various natural alkaloids, like theinc, creatine, and morphine. The best way of preparing it is to warm brom- acetamide with caustic potash (see p. 163). ALKYLAMINES AND ALKYL AMMONIUM DERIVATIVES. 167 Methylamine is a colorless gas, with an ammoniacal odor; it con- denses in the cold to a liquid boiling at 6. Its combustibility in the air distinguishes it from ammonia. At 12 one volume of water dissolves 1150 volumes of the gas. The aqueous solution manifests all the properties of aqueous ammonia, but does not, however, dissolve the oxides of cobalt, nickel, and cadmium. Methyl ammonium chloride melts at 210. Methyl ammonium picrate dissolves with difficulty, and melts at 207. Ethylamine, C 2 H 5 .NH 2 , is a mobile liquid, which boils at 18 and has a sp. gr. of 0.696 at 8. It mixes with water in all propor- tions. It expels ammonia from ammoniacal salts, and when in excess redissolves aluminium hydroxide ; otherwise it deports itself in every respect like ammonia. Propylamine, C 3 H. . NH 2 , boils at 49 ; isopropylamine, C 3 H 7 . NH 2 , obtained from dimethyl acetoxime, (CH^C: N . OH (see p. 161), boils at 32 (B. 20, 505). The higher alkylamines with an odd number of carbon atoms are most easily obtained from the nitriles of the fatty acids, C n H 2n + X CN (p. 162, B. 22, 812). The alkylamines with an even number of carbon atoms are prepared from the acid amides (p. 163, B. 21, 2486). Butylamine, C 4 H 9 .NH 2 (normal), boils at 76 ; isobutylamine, C 4 H 9 . NH 2 , obtained from fermentation butyl alcohol, boils at 68. Tertiary Butylamine, Trimethyl Carbinamine, boils at 43. Normal Amylamine, C 5 H n . NH 2 , boils at 103. Isoamylamine, C 5 H n . NH 2 , is a liquid boiling at 95; it is obtained from leucine by distillation with caustic potash. It is miscible with water, and burns with a luminous flame. Diethyl carbinamine, (C 2 H 5 ) 2 CH . NH 2 , boils at 90. Di-n-propyl carbinamine (C 3 H 7 ) 2 CHNH 2 , boils at 130; di-iso-butyl carbina- mine, (C 4 H.) 2 CHXH 2 , melts at 166. All these are obtained from the corresponding ketoximes by reduction with sodium and alcohol (B. 27, R. 200). n-Nonylamine, C 9 H 19 . NH 2 , boils at about 195, and is sparingly soluble in water. (2) Secondary Amines. The secondary amines are also desig- nated imide bases. Simple Secondary Amines : Dimethylamine, NH(CH 3 ) 2 , is most conveniently obtained by boiling nitroso-dimethyl aniline or dinitro-dimethyl aniline with caustic potash (A. 222, 119). It is a gas that dissolves readily in water. It is condensed to a liquid by cold, and boils at 7.2. Diethylamine, NH(C 2 H 5 ) 2 , is a liquid boiling at 56, and is readily soluble in water. Its HCl-salt fuses at 176 and its picrate at 155 (B. 29, R. 590). Di-n-propylamine boils at IIO. Di-isopropylamine boils at 84 (B. 22, R. 343). Mixed secondary amines are produced by methods 30 and ~$b. Methyl-ethylamine boils at 35. Metkyl-n-propylamine boils at 63. Methyl-n-butylamine boils at 91. Methyl-n-heptylamine boils at 171 (B. 29, 21 lo). (3) Tertiary Amines. These are also called nitrile bases, to dis- tinguish them from alky I cyanides or acid nitriles. Trimethylamine, N(CH 3 ) 3 . This is isomeric with ethyl-methyl- amine, C 2 H 5 . NH . CH 3 , and the two propylamines, C 3 H 7 . NH 2 . It is 1 68 ORGANIC CHEMISTRY. present in herring-brine, and is produced by distilling betaine (from the beet) with caustic potash. It is prepared from herring-brine in large quantities, and also by the distillation of the " vinasses " of the French beet root. Trimethylamine is a liquid, very soluble in water, and boils at 3.5. The penetrating, fish-like smell is characteristic of it. Its HCl-salt melts at 271-275, and its sparingly soluble picrate at 216 (B. 29, R. 590). Triethylamine, N(C 2 H 5 ) 3 , boils at 89, and is not very soluble in water. It is produced by heating ethyl isocyanate with sodium ethylate : CO : N . C 2 H 5 -f- 2C 2 H 5 . ONa == N(C 2 H 5 ) 3 + CO 3 Na 2 . (4) Tetraalkyl Ammonium Bases. While neither ammonium hydroxide nor mono-, di-, or tri-alkyl ammonium hydroxides have been prepared, yet, by the addition of the alkyl iodides to the tertiary amines, tetraalkyl ammonium iodides are produced ; when treated with moist silver oxide they yield the ammonium hydroxides : N(C 2 H 5 ) 4 I + AgOH = N(C 2 H 5 ) 4 . OH -f Agl. These hydroxides are perfectly analogous to those of potassium and sodium. They possess strong alkaline reaction, saponify fats, and deliquesce in the air. They crystallize when their aqueous solutions are concentrated in vacuo. With the acids they yield ammonium salts ; these usually crystallize well. On exposure to strong heat they break down into tertiary amines and alcohols, or their decomposition products (C n H 2n and H 2 O) : N(C 2 H 5 ) 4 . OH = N(C 2 H 5 ) 3 + C 2 H 4 + H 2 O. This reaction has acquired special significance because of its appli- cation in the decomposition of ring-shaped bases (see piperidine or pentamethylene imide). Tetramethyl Ammonium Iodide or Tetramethylium, Iodide, N(CH 3 ) 4 I, and Tetraethyl Ammonium Iodide or Tetraethylium Iodide, N(C 2 H 5 ) 4 I, from trimethylamine (triethylamine) and ethyl iodide, consist of white prisms crystallized from water or alcohol. Tetramethylium Hydroxide, N(CH ? ) 4 OH, and Tetraethylium Hy- droxide, N(C 2 H 5 ) 4 OH, consist of deliquescent needles with a strong alkaline reaction. They result when the corresponding iodides are treated with moist silver oxide. Iodine Addition Products. (C 2 H 5 ) 4 NI . I 2 , (C 2 H 5 ) 4 NI . 2l ? , and addition products containing even more iodine molecules, are precipitated by iodine from the aqueous solutions of the tetraalkylium iodides, e. g., tetraethylium iodide. Of the numerous compounds belonging here we may mention : \ Dimethyl-diethyl Ammonium Iodide, , rr 3 / 2 > NI, obtained from dimethyl- amine and ethyl iodide, and from diethylamine and methyl iodide : CH 3 ") C 2 H 5 CH, I N . C 2 H,I and C 2 H 5 C 2 H 5 J CH 3 ALKYLAMINES AND ALKYL AMMONIUM DERIVATIVES. 169 These two compounds are identical (A. 180, 173). They demonstrate, too, that the ammonium compounds are not molecular derivatives, as formerly assumed (the above formulas are only intended to exhibit the different manner of formation), but represent true atomic compounds. They further show the equivalence of the five nitrogen valences (compare Le Bel, B. 23, R. 147). For the dissymmetry and the appearance of rotatory power in alkyl derivatives of ammonium chloride, compare Le Bel, B. 24, R. 441, who succeeded, by use of germ vegetation, in changing isobutyl-propyl-ethyl-methyl-ammonium chloride into an optically active modification. (b] Unsaturated Amines and Ammonium Bases. Vinylamine, CH 2 = CH . NH 2 , boiling at 55, is only known in solution. It results from the action of silver oxide or potassium hydroxide upon brom-ethylamine (see this). It unites with sulphur dioxide to form Taurine (see this) : CH 2 NH 2 KOH CH NH 2 so CH 2 NH 2 I > II -H^T-> I Taurine. CHjBr CH 2 CH 2 SO 3 H Vinylamine is a transparent liquid with a strong ammoniacal odor. It corrodes the skin, and is soluble in water. Vinyl Picrate melts at 142 (B. 28, 2929). Trimtthyl-vinyl Ammonium Hydroxide or ^VJ?wr/^,-CH 2 = CH . N(CH 3 ) 3 OH, is described after glycol with choline, to which it is intimately related. Allylamine, CH 2 = CH . CH 2 . NH 2 , from mustard oil (see this), boils at 58. ' hoallylamint, Propenylamine, CH 3 . CH = CHNH 2 , boils at 67. It is pro- duced by the action of caustic potash on /3-brompropylamine (B. 29, 2747). Dimethyl Piperidine, Pentallyl Dimethylamine, CH 2 = CH . CH 2 . CH 2 . - CH 2 . N(CH 3 ) 2 . It is a decomposition product of piperidine (see this). It boils at 117-118. This and similar bases take up hydrochloric acid, and when heated yield ammonium chlorides of pyrrolidine bases (A. 278, i). Propargylamine, CH = C.CH 2 NH 2 , from dibromallylamine, CH 2 Br.CHBr.- CH 2 NH 2 , and alcoholic potash, is probably a gas in a free condition. It could only be obtained in alcoholic solution or in the form of salts (B. 22, 3080). (c) Alkylamine Halides. These bear the same relation to NC1 3 and NI 3 as the alkylamines sustain to ammonia. The alkylamine chlorides and bromides may also be regarded as the amides of hypochlorous and hypobromous acids". Such derivatives are produced by the action of chlorine, bromine, or iodine alone, or in the presence of caustic alkalies, upon primary and secondary amines (6.8,1470; 9,146; 16,558; 23, R. 386; A. 230, 222), as well as by the transposition of acetdibromamide (see this) with amines. When saponified they yield hypochlorous, hypobromous, and hypoiodous acids (B. 26, 985) : CH 3 .CH 2 .CH 2 NH 2 ^CH 3 .CH 2 .CH 2 NHC1 - ^CH 3 .CH 2 .CH 2 .NC1 2 (CH 3 .CH,CHJ 2 NH - > (CH 3 CH 2 CH 2 ) 2 NC1. The primary alkylamine mono-halides are more unstable than the dihalides and the secondary halogen-amines. J\Iethylamine Diiodide, CH 3 NI 2 , is garnet-red in color. Dimethylamine Iodide, (CHj)jNI,is sulphur-yellow in color. Ethylamine Dichloride is an unstable oil, with penetrating odor, and boils at 88-89. Propylamine Chloride, C 3 H 7 NHC1, volatilizes with decomposition. Propylamine Dichloride, C 3 H 7 NC1 2 , is a yellow oil, boiling at 117. Dipropylamine Chloride, (C S H 7 ) 2 NCI, boils at 143 (B. 8, 1470; 9, 146; 16, 558; 23, R. 386; 26, R. 188; A. 230, 222). Nitriles result when the dibromides of the higher primary alkylamines are treated with alkalies. 15 I 70 ORGANIC CHEMISTRY. (d) Sulphur-containing Derivatives of the Alkylamines. 1. Thiodialkylamines, Thiotetralkyldiamines, result from the action of SC1 2 upon dialkylamines in ligro'ine solution. Thiodiethylamine, S[N(C 2 H 5 ) 2 ] 2 , boils at 87 (19 mm.) (B. 28,575). 2. Dithiotetralkylamines, Dithiotetralkyldiamines, result from the action of S 2 C1 ? upon dialkylamines in ethereal solution. Dithiodimethylamine, S 2 [N(CH 3 ) 2 ] 2 , boils at 82 (22 mm.). Dithiodiethylamine boils at 137 (29 mm.) (B. 28, 166). 3. Alkyl-thionylamines, alkylized imides of sulphurous acid, are formed when thionyl chloride (i mol.) acts upon a primary amine (3 mols.) in ethereal solution (Michaelis A. 274, 187) : 3CH 3 NH 2 -f SOC1 2 = CH 3 N = SO + 2CH 3 NH 2 . HC1. The members of the series with low boiling points are liquids with penetrating odor, and fume in the air. Water decomposes them into SO 2 and the primary amine. Thionyl-methylamine, CH 3 NSO, boils at 58-59. Thionyl-ethylamine boils at 70- 75. Thionyl-isobutylamine, (CH^CH . CH 2 . N : SO, boils at 117. 4. Thionyl Dialkylamines, Thionyl Tetralkyldiamines, are formed when thionyl chloride acts upon the ethereal solution of the dialkylamines. Thionyl Diethy 'la mine, OS[N(C 2 H 5 ) 2 ] 2 , boiling at 118 (27 mm.), corresponds in its composition to tetra- ethyl urea (B. 28, 1016). 5. Thionamic Acids are the products resulting from the interaction of sulphur dioxide and primary amines : C 2 H 5 NH . SO 2 H, ethyl thionamic acid, a white hygro- scopic powder. 6. Alkyl Sulphamides and Alkyl Sulphaminic Acids. Sulphamides, e. g. , are formed by the action of sulphuryl chloride, SO 2 C1 2 , upon the free secondary amines, whereas their chlorides, SO 2 CH 3 N(NO 2 )CO 2 CH 3 - > CH 3 . NH . NO 2 . The imide hydrogen atom of the monoalkyl nitramines can be replaced by metals. Simple and mixed dialkyl nitramines result from the transposition of the potassium alkyl nitroamine derivatives with alkylogens. By reduction of the dialkyl nitramines with zinc dust and acetic acid, unsymmetrical dialkyl hydrazines are produced. ALKYLAMINES AND ALKYL AMMONIUM DERIVATIVES. I 71 Methyl-nitramine, CH 3 . NH(NO 2 ), melts at 38. Ethyl-nitramine, C 2 H 5 . - MI NO 2 ), melts at 3. Propyl-nitramine boils at 128 (40 mm.). Butyl - nitramine, see B. 28, R. 1058. Simple Dialkyl-nitramines : Dimethyl-nitramine, (CH 3 ) 2 N . NO 2 , melts at 58, boils at 187, and is produced, together with an isomeride, boiling at 112, by the distillation of mono-methyl-nitramine (B. 29, R. 910), as well as upon treating dimethylamine and nitric acid with acetic anhydride (B. 28,402). Dielhyl-nitraniine boils at 206. Dipropyl-nitramine boils at 77 (10 mm.). Mixed Nitramines : Methyl-ethyl-nitramine boils at 190. Methyl-propyl-nitramine boils at 115 (40 mm.). Methyl-butyl-nitramitu melts at +0.5 (B. 29, R. 424). Methyl-allyl- nitramine, boiling at 95 (18 mm.), is obtained, together with an isomeride, boiling at 51 (18 mm.), by the interaction of potassium methyl-nitramine and allyl bromide. (g) Alkyl-hydrazines. Just as the amines are derived from ammonia, NH 3 , so the hydra- zines are derived from hydrazine or diamide, H 2 N NH 2 , an analogue of liquid hydrogen phosphide, H 2 P PH 2 . Long before hydrazine in a free state was obtained from diazo-acetic acid (see this), its derivatives had been prepared by a variety of methods. They hold an important place in the benzene series (see phenylhydrazine, C 6 H 5 . NH . NH 2 ) (E. Fischer, A. 99, 281). The mono-alkyl hydrazines are obtained from the mono-alkyl ureas, NH 2 . CO . - NH.R, and from the symmetrical dialkylureas by their conversion into nitroso- compounds, and the reduction of the latter to hydrazines of the ureas : CH 3 NH CQ - ld CH 3 .NH >C CH,.NH > CH,NH> CH 3 .N^ CH 3 .N^ \NO When the latter are heated with alkalies or acids they split up, like all urea deriv- atives, into their components, CO 2 , alkylamine and alkylhydrazine. They reduce Fehling's solution in the cold, while heat is necessary to effect this when using the dialkyl hydrazines. In this respect they differ from the amines, which they so closely resemble in properties. Methyl Hydrazine, CH 3 . NH . NH 2 , is a very mobile liquid, boiling at 87. Its odor is like that of methylamine. In the air it absorbs moisture and fumes (B. 22, R. 670). Ethyl Hydrazine, (C 2 H 5 )HN. NH 2 , boils at 100. When ethyl hydrazine is acted upon by potassium disulphate, potassium ethyl hydrazine siilphonate, C 2 H 5 . NH NH . SO 3 K, is formed. Mercuric oxide changes this to potassium diazo-ethyl sulphonate, C 2 H 5 . N = N. SO 3 K. This is the only well-known representative in the fatty-series of a numerous and highly important class of derivatives of the benzene series the diazo-compounds. They are charac- terized by the diazo group, N=N , which is in union with carbon radicals. *- Dialkyl hydrazines result, through the action of hydrochloric acid, from the cor- responding diformyl compounds, which are the reaction products of alkyl iodides and lead diformyl-hydrazine. *-Diethyl hydrazine, C 2 H 5 NH NH . C 2 H 5 , boils at 85 (B. 27, 2279\ The uns-Dialkylhydrazines, like (CH 3 ) 2 N . NH 2 , are formed by the reduction of nitroso-amines and dialkyl nitramines (B. 29, R. 424), in aqueous and alcoholic solu- tion, by zinc dust and acetic acid : (CH 3 ) 2 N. NO + 2H 2 = (CH 3 ) 2 N. NH 2 + H 2 O. uns-Dimethyl Hydrazine, (CH 3 ) 2 N.NH 2 , and uns-Diethyl Hydrazine. (C,H 5 ) 2 N . NH 2 , are mobile liquids, of ammoniacal odor, and readily soluble in 172 ORGANIC CHEMISTRY. water, alcohol, and ether. Diethyl hydrazine boils at 97, and the dimethyl com- pound at 62. Thionyl Diethylhydrazine, (C 2 H 5 ) 2 N . NSO, boils at 73 under 20 mm. (B. 26, 310). Diethylhydrazine unites with ethyl iodide and yields the compound (C 2 H 5 ) 2 . - v NR X . XII 2 . C 2 H 5 I, which is to be viewed as the ammonium iodide, (C 2 H 5 ) 3 N< 2> as it is not decomposed by alkalies, and moist silver oxide converts it into a strong alkaline hydroxide. Nascent hydrogen (zinc and sulphuric acid) decomposes this iodide into triethylamine, ammonia, and hydrogen iodide. This reaction is an additional proof that the ammonium compounds represent atomic derivatives of quinquivalent nitrogen (A. 199, 318). (//) Tetra-alkyl-tetrazones. When mercuric oxide acts upon diethylhydrazine, tetraethyl-tetrazone, (C 2 H 5 ) 2 N . - N : N . N(C 2 H 5 ) 2 , is formed. This is a strong basic liquid with an alliaceous odor. Methyl-bitty l-tetrazone boils at 121 (19 mm.) (B. 29, R. 424). (/) Alkyl Hydroxylamine Derivatives. The entrance of one alkyl group into hydroxylamine produces two isomeric forms : NH 2 . O . CH 3 and CH 3 . NH . OH. a-Methyl-hydroxylamine. /3-Methyl-hydroxylamine. The derivatives of both varieties are obtained from the isomeric benzaldoximes (see these). The ^-compounds are formed from syn-meta-nitrobenzaldoxime by alkylization with sodium alcoholate and an alkyl iodide, together with the subsequent splitting-off of the ether by means of concentrated hydrochloric acid (B. 23, 599 ; 26, 2377, 2514). a-Derivatives result from the breaking down of alkyl benzhydrox- amic esters, and the /3-bodies are intermediate products in the reduction of the nitro- paraffins with stannous chloride, or, better, with zinc dust and water (B. 27, 1350). a-Methylhydroxylamine, NH 2 . O . CH 3 , Methoxylamine, yields an HCl-salt, which melts at 149. It differs from hydroxylamine in that it does not reduce alkaline copper solutions. a-Ethylhydroxylamine, NH 2 . . C 2 H 5 , Ethoxylamine, boils at 68. $-Methylhydroxylamine, CH 3 .NH.OH, melts at 41-42, and boils at 61-62 (i6mm.) (B. 23, 3597; 24, 3528; 25, 1716; 26, 2514). (3 -Ethylhydro xylamine melts at 59-60. The action of ethyl bromide upon ethoxylamine produces Diethylhydroxylaminc, C 2 H 5 . NH . O . C 2 H 5 , and Triethylhydroxylamine , (C 2 H 5 ) 2 . N . O . C 2 H 5 , boiling at 98 (B. 22, R. 590). Triethylamine Oxide, (C 2 H-) 3 N :O, an isomeride of the latter, has been prepared by the interaction of zinc ethide and nitroethane. It boils (/) Phosphorus Derivatives of Secondary Alkylamines (B. 29, 710). 1. Dialkylamine Chlorphosphines are formed when phosphorus trichloride acts upon dialkylamines. They are liquids having a sharp, penetrating odor ; they fume in the air. Diethylamine Chlorphosphine, (C 2 H 5 ) 2 N . PC1 2 , boils at 100 (14 mm.). Di-isobutylamine Chlorphosphine melts at 37 and boils at 1 1 6 (16 mm.). 2. Dialkylamine Oxychlorphosphines. These result when phosphorus oxychloride acts upon secondary amines in ethereal solution. They are stable in the air, and possess an aromatic odor resembling that of camphor or pepper. Dialkylamine Oxychlorphosphine, (C 2 H 5 ) 2 N . POC1 2 , boils at loo (15 mm.). Di-n-propylamim Oxychlorphosphine boils at 170 (80 mm.). Di-isobiitylamine Oxychlorphosphine melts at 54. PHOSPHORUS DERIVATIVES OF THE ALCOHOL RADICALS. 173 3. Dialkylamine Snlphochlorphosphines result from the interaction of phosphorus sulphochloride and the dialkylamines. They are volatile in steam. Their odor is like that of camphor. Diethylamine Siilphochlorphosphine, (C 3 H 5 ) 2 NPSC1 2 , boils at 100 (15 mm.). Dipropylamine Siilphochlorphosphine boils at 133 (15 mm.). Di-isolnitylamine Sulphochlorphosphine boils at 150 (IO mm.). (/) (w) (;/) Arsenic, Boron, and Silicon Derivatives of Secondary Amines (B. 29, 714). (/) Di-isobulylamine Chlorarsine, (C 4 H 9 ^ a N . AsCl 2 , boils at 125 (15 mm.). (m) Diethylamine Chlorborine, (C 2 H 5 ) 2 N . BC1 2 , boils at 142, and fumes very strongly in the air. Dipropylamine Chlorborine boils at 99 (45 mm.). Di- isobuiylamine Chlorborine boils at 93 (17 mm.). () Diethylamine Chlorsilicide, (C 2 H 5 ) 2 N . Sid 3 , boils at 104 (80 mm.). Di- isobutylamine Chlorsilicide boils at 122 (30 mm.). The chlorarsines, chlorborines, and chlorsilicides are prepared from their corresponding chlorides. 6. PHOSPHORUS DERIVATIVES OF THE ALCOHOL RADICALS. A. PHOSPHORUS BASES OR PHOSPHINES AND ALKYL PHOSPHONIUM COMPOUNDS. Hydrogen phosphide, PH 3 , has slight basic properties. It unites with HI to phosphonium iodide, which is resolved again by water into its components. The phosphorus bases or phosphine s, obtained by the replacement of the hydrogen of PH 3 by alkyls, have more of the basic character of ammonia and approach the amines in this respect. The basic character increases with the number of alkyl groups. (1) They oxidize very energetically on exposure to the air, usually with spontaneous ignition; hence they should be prepared away from air contact. Moderate oxidation with nitric acid converts the primary phosphines into alkyl phosphoric acids, 'the secondary phosphines into alkyl phosphinic acids, while the tertiary phosphines, in -the presence of air, pass into alkyl phosphinic oxides : Ethyl Phosphine: C 2 H 5 PH, - > C 2 H 5 PO(OH) 2 Ethyl Phosphoric Acid Diethyl Phosphine: (C,Hj,PH > (C 2 H 5 ) 2 PO(OH) Diethyl Phosphinic Acid Triethyl Phosphine: (C 2 H 5 ) 3 P - -> (C 2 H 5 ) 3 PO Triethyl Phosphine Oxide. (2) They combine readily with sulphur and carbon disulphide (B. 25, 2436) ; also with the halogens. (3) The primary phosphines, e. g., PH 3 , are feeble bases. Their salts, like PH 4 I, are decomposed by water. Caustic potash is required for the decomposition of the salts, of the secondary and tertiary phosphines. (4) The tertiary phosphines combine with the alkyl iodides to form tetra-alkyl phosphonium iodides. These are just as little decomposed by caustic potash as the tetra-alkyl ammonium iodides. Moist silver oxide liberates tetra-alkyl phosphonium hydroxides from them ; these, like the tetra-alkyl ammonium hydroxides, are stronger bases than the alkalies : P(CH 3 ) 3 ; > P(CH 3 )J -^ P(CH 3 ) 4 OH. 174 ORGANIC CHEMISTRY. Thenard (1846) discovered the tertiary phosphines, and A. W. Hofmann (1871) first prepared the primary and secondary phosphines (B. 4, 430). Formation. (I) By letting the alkyl iodides act upon phosphonium iodide for six hours in the presence of certain metallic oxides, chiefly zinc oxide, at 150. The product is a mixture of P(C 2 H 5 )H 2 . HI and P(C 2 H 5 ) 2 H . HI, the first of which is decomposed by water. The Hi-salt of the diethyl phosphine is not affected, but by boiling the latter with sodium hydroxide, diethyl phosphine is set free (A. W. Hof- mann) : 2PHJ -f 2C 2 H 3 I + ZnO = 2[P(C 2 H 5 )H 2 . HI] + ZnI 2 .+ H 2 O PHJ + 2C 2 H 5 I -f ZnO = P(C 2 H 5 ) 2 H . HI + ZnI 2 + H 2 O. P(C 2 H 5 )H 2 HI 5^0 ^ P(C 2 H 5 )H 2 + HI. (2) Tertiary phosphines and phosphonium iodides are produced by heating phos- phonium iodide with alkyl iodides (methyl iodide) to 150-! 80 without the addi- tion of metallic oxides. They can be separated by means of caustic potash : PHJ + 3 CH 3 I = P(CH 3 ) 3 . HI + 3 HI P(CH 3 ) 3 HI + CH 3 I = P(CH 3 ) 4 . I + HI. (3) Tertiary phosphines result when alkylogens act upon calcium phosphide (Thenard), and (4) in the action of zinc alkyls upon phosphorous chloride: 2PC1 3 + 3 Zn(CH 3 ) 2 = 2P(CH,) 8 + 3 ZnCl 2 . The phosphines are colorless, strongly refracting, extremely powerful-smelling, volatile liquids. They are scarcely soluble in water, but dissolve readily in alcohol and ether. They oxidize very readily and show neutral reaction. (1) Primary Phosphines: Methyl Phosphine, P(CH 3 )H 2 , condenses at 14 to a mobile liquid. Ethyl Phosphine, P(C 2 H 5 )H 2 , boils at 25. Isopropyl Phosphine, P(C 3 H t )H 2 , boils at 41, and the isobutyl derivative, P(C 4 H 7 )H 2 , at 62. Fuming nitric acid oxidizes the primary phosphines to alkyl phospho-acids ; their Hi-salts are decomposed by water. (2) Secondary Phosphines : Dimethyl Phosphine, P(CH 3 ) 2 H, boils at 25 C. Diethyl Phosphine, P(C 2 H 5 ) 2 H, boils at 85. Di-isopropyl Phosphine, P(C 3 H 7 ) 2 H, boils at 118. Di-isoamyl Phosphine, P(C 5 H n ) 2 H, boils at 2IO-2I5, but is not self-inflammable. Fuming nitric acid oxidizes this class of phosphines to dialkyl phosphinic acids. Water does not decompose the Hi-salts of the secondary phosphines. (3) Tertiary Phosphines : Trimethyl Phosphine, P(CH 3 ) 3 , boils at 40. Triethyl Phosphine, P(C 2 H 5 ) 3 , boils at 117. Both tertiary phosphines form phosphine oxides by the absorption of oxygen (B. 29, 1707). They also combine with S, C1 2 , Br 2 , the halogen hydrides, and the alkylogens. Carbon disulphide also combines with triethyl phosphine, and the product is P(C 2 H 5 ) 3 . CS 2 , crystallizing in red leaflets. It is insoluble in water, fuses at 95, and sublimes without decomposition. Its production will answer for the detec- tion of carbon disulphide. According to almost all of these reactions, triethyl phosphine resembles a strongly positive bivalent metal for example, calcium. By the addition of three alkyl groups, the quinquivalent, metalloidal phosphorus atom acquires the character of a bivalent alkaline earth metal. By the further addition of an alkyl to the phosphorus in the phosphonium group, P(CH 3 ) 4 , the former acquires the properties of a univalent alkali metal. Similar conditions manifest themselves with sulphur, with tellurium, with arsenic, and also with almost all the less positive metals. (4) Phosphonium Bases. The tetra-alkyl phosphonium bases resemble, in a very high degree, both in formation and properties, the tetra-alkyl ammonium bases. ARSENIC ALKVL COMPOUNDS. 175 Tetra-methyl- and Telra-ethyl-phosphoniitm Hydroxide, P(C 2 H 5 ) 4 . OH, are crystal- line masses which deliquesce on exposure to the air. They show a strong alkaline reaction. When they are heated they show the great affinity of phosphorus for oxygen, for, unlike the corresponding ammonium derivatives, they break down into a trialkyl phosphine oxide and a paraffin. Thus tetra-niethyl-phosphonintn hydroxide yields trimethyl phosphine oxide and methane : P(CH 3 ) 4 . OH = P(CH 3 ) 3 O -f- CH 4 . Tetramethyl- and Tetra-ethyl phospkonium iodide, P(C 2 H 5 ) 4 I, are white, crystal- line bodies. Heat decomposes them into trialkyl phosphines and alkyl iodides. B. ALKYL PHOSPHO-ACIDS. These acids result, as previously mentioned, from the moderated oxidation of the primary phosphines with nitric acid. They are derived from unsymmetrical phos- phorous acid, HPO(OH) 2 . Methyl Phospho-acid, CH 3 PO(OH) 2 , melts at 105. PC1 5 converts it into CH 3 POC1 2 , melting at 32 and boiling at 163. The ethyl phospho-acid, C 2 H 5 (OH) 2 PO. melts at 44. C. ALKYL PHOSPHINIC ACIDS. These are derived from hypophosphorous acid, H 2 PO(OH). They are produced, as described, by oxidizing the secondary phosphines with fuming nitric acid. Dimethyl Phosphinic Acid, (CH 3 ) 2 PO(OH), resembles paraffin. It melts at 76 and volatilizes without decomposition. See B. 25, 2441, for diethyl-dithio-phosphinic acid, (C 2 H 5 ) 2 - PSSH. D. ALKYL PHOSPHINE OXIDES. arise when the tri-alkyl phosphines are oxidized in the air, or by mercuric oxide ; also in the decomposition of the letra-alkyl phosphonium hydroxides by heat. Triethyl Phosphine Oxide, P(C 2 H 5 ) 3 O, melts at 53 and boils at 243. It forms, for example, P(C 2 H 5 ) 3 C1 2 , with haloid acids, from which Na regenerates triethy I phosphine when aided by heat. The corresponding tri-ethyl phosphine sulphide, P(C 2 H 5 ) 3 S, from triethyl phosphine and sulphur, melts at 94. Derivatives of PC1 3 , corresponding to the alkyl chloramines, are known (B. 13, 2174). 7. ARSENIC ALKYL COMPOUNDS. Arsenic is quite metallic in its character ; its alkyl compounds con- stitute the transition from the nitrogen and phosphorus bases to the so-called metallo-organic derivatives /. e., the compounds of the alkyls with the metals (p. 182). The similarity to the amines and phosphines is observed in the existence of tertiary arsines, As(CH 3 ) 3 , but these do not possess basic properties, nor do they unite with acids. They show in a marked degree the property of the tertiary phosphines, in their uniting with oxygen, sulphur, and the halogens to form com- pounds of the type As(CH 3 ) 3 X 2 . Mono- and dialkyl arsines are not known. Tri-alkyl derivatives exist. These are, however, not so im- 176 ORGANIC CHEMISTRY. portant as the cacodyl compounds have been in the development of organic chemistry. In 1760 Cadet discovered the reaction which led to the study of the arsenic alkyls. He distilled arsenious acid together with potassium acetate, and obtained a liquid which was subsequently named, after its discoverer, Cade '/' 's fuming, arsenical liquid. From 18371843 Bunsen carried out a series of splendid investigations (A. 37, I ; 42, 14; 46, l), and demonstrated that the chief constituent of Cadet's liquid was " alkarsine," or cacodyl oxide, whose radical "cacodyl" Bunsen also succeeded in preparing. Berzelius proposed the name cacodyl (from /ca/cwJ^c, stinking] for this very poisonous body with an extremely disgusting odor. Bunsen showed that it conducted itself like a compound radical. Together with the cyanogen of Gay- Lussac, and the benzoyl of Liebig and Wohler, assumed to be present in the benzoyl derivatives, it formed a strong support for the radical theory. But later it was found that cacodyl was no more a free radical than was cyanogen, but that, in accordance with the doctrine of valence, it was rather a compound of two univalent radicals As(CH 3 ) 2 As(CH 3 ) 2 , combined to a saturated molecule : | As(CH 3 ) 2 . Valuable contributions have been made to the chemistry of the arsenic alkyls by Cahours and Riche (A. 92, 361), by Landolt (A. 92, 370), and particularly by Baeyer, who discovered the monomethyl arsenic derivatives, and made clear the connection existing between the alkyl-arsenic derivatives (A. 107, 257). The following reactions give rise to arsenic alkyl compounds : (1) Cacodyl Oxide, or Alkarsine, is produced by the distillation of potassium acetate and arsenious acid. This is a delicate test, both for arsenic and for acetic acid : 4CH 3 . CO 2 K -f As 2 O 3 = [(CH 3 ) 2 As] 2 O + 2CO 3 K 2 -f 2CO 2 . (2) By the action of zinc alkyls upon arsenic trichloride, and (3) by the action of the alkyl iodides upon sodium arsenide : 2AsCl 3 + 3Zn(CH 3 ) 2 = 2As(CH,) 8 + 3 ZnCl 2 AsNa 3 + 3 C 2 H 5 I = As(C 2 H 5 ) 3 + 3 NaI. (4) The transposition of trisodium arsenite by alkyl iodides gives rise to the sodium salts of alkyl arsonic acid (A. 249, 147) : , AsO 3 Na 3 + CH 3 T = CH 3 AsO(ONa) 2 -f Nal. Table of the Alkyl- (Methyl-'] Derivatives of Arsenic. CH 3 AsCl 2 , - CH aAsO, e . CH 3 . AsO(OH) 2 , (CH,) f AsCl, Cacodyl Chloride. [(CH 3 ) 2 As] 2 O, Q (CH 3 ) 2 AsO.OH, C ^ l (CH 3 ) 3 As, Trimethyl Arsine. (CH 3 ) 3 AsO, Trimethyl Arsine Oxide. (CH 3 ) 4 AsI, ^on^^odide (CH s ) 4 AsOH, Tetramethyl Arsonium Hydroxide. (CH 3 ) 2 -As * | , Cacodyl. (CH 3 ) 2 -As MONO-ALKYL ARSINE COMPOUNDS. 177 MONO-ALKYL ARSINE COMPOUNDS. The formation of monomethyl arsenic chloride, As(CH 3 )Cl 2 , is due to the property, possessed by the derivatives of the type AsX,,, of adding two halogen atoms (C1 2 ) and passing into compounds of the form AsX-. The more chlorine atoms these bodies contain, the more readily do they split off methyl chloride. Thus As(CH 3 )Cl 4 breaks down, at o, into AsCl 3 and CH' 3 C1, and As(CH 8 ) t CL, at 50, into As(CH.)CL and CH,C1 : As(CH 3 ) 3 -^-^ As(CH 3 ) 3 Cl 2 - > CH 3 C1 + As(CH 3 ) 2 Cl As(CH 3 ) 2 Cl - -^- > As(CH 3 ) 2 Cl 3 ^-^ CH 3 C1 + As(CH 3 )Cl 2 As(CH 3 )Cl 2 + C ' 3 -> As(CH 3 ) C1 4 > CH 3 C1 -f AsCl 3 . Methylarsen-dichloride, As(CH 3 )Cl 2 , results in the decomposition of cacodylic acid, and of As^CH 3 ) 2 Cl 3 , with hydrochloric acid : As(CH 3 ) 2 . OH + 3 HC1 = As(CH 3 )Cl 2 -f CH 3 C1 + 2H 2 O. It is a heavy liquid, soluble in water, and boils at 133. At IO it unites with chlorine, forming As(CH 3 )Cl 4 . From the alcoholic solution hydrogen sulphide pre- cipitates the sulphide, As(CH 3 )S, melting at llo. When sodium carbonate acts upon the aqueous solution of the dichloride methyl- arsenoxide, As(CH 3 )O, is formed. It melts at 95, and distils along with steam. The oxide is basic, and may be converted by the haloid acids and H 2 S into the halogen derivatives, AsCH 3 X 2 , and the sulphide, AsCH 3 S. Silver oxide, acting upon the aqueous solution of the above oxide, changes it into the silver salt of monomethyl arsonic acid, (CH 3 )AsO(OH) 2 , an analogue of methyl phospho-acid (p. 175). When ethyl iodide acts upon sodium arsenite, AsO 3 Xa 3 , sodium monoethyl arsonate, C 2 H 5 . AsO(OXa) 2 , is produced. Dimethyl Arsine Derivatives. Cacodylic oxide or alkarsine, /j. \ 2 \ S '-- > O, is the starting-out material for the preparation of the dimethyl compounds. Its formation from potassium acetate and arsenic trioxide has already been given on p. 176. The crude oxide ignites spontaneously in the air. This is due to the presence in it of a slight amount of free cacodyl. When prepared from cacodyl chloride by caustic potash it does not inflame spontaneously, and is a liquid with a stupefying odor. It solidifies at 25. It boils at 120, and at 15 has a specific gravity of 1.462. It is insoluble in water, but readily solu- ble in alcohol and in ether. Dimethyl Arsine, Cacodyl Hydride, (CH 3 ),AsH, boils at 36. It is produced when zinc and hydrochloric acid act upon cacodyl chlo- ride in alcoholic solution. It is a colorless, mobile liquid, with the characteristic cacodyl odor. It inflames spontaneously in the air (B. 27, 1378). Cacodyl Chloride, As(CH 3 ) 2 Cl, is formed by heating trimethyl arsen-dichloride. As(CH 3 V,Cl 2 (see above) and by acting upon cacodyl oxide with hydrochloric acid, as well as from C1 2 and cacodyl. It is more readily obtained by heating the corro- sive sublimate compound of the oxide with hydrochloric acid. It boils at 100. It unites with chlorine to form the trichloride, As(CH 3 ) 2 Cl 3 , which renders possible the transition from the dimethyl compounds to the monomethyl derivative^. u* ^\ TTKIVERSITT 178 ORGANIC CHEMISTRY. Cacodyl Sulphide, A S >^Tr 3 ( 2 >S,from cacodyl chloride and barium sulphide, in- As^n 3 j 2 flames in the air. Cacodyl Cyanide, As(CH 3 ) 2 . CN, is formed by heating cacodyl chloride with mercuric cyanide. It fuses at 33 and boils at 140. Cacodylic Acid, (CH 3 ) 2 AsO . OH (see p. 175), corresponds in its composition to dimethyl phosphinic acid. Cacodyl oxide, by slow oxidation, passes into cacodyl cacodylate, which breaks down, when distilled with water, into cacodylic oxide and cacodylic acid : As(CH 3 ) As(CH 3 ) As(CH 3 ) 2 > -OAs(CH 3 ) 2 > 2 OA S S (CH 3 3 J 2 > + H * = [ As (CH 3 ) 2 ] 2 + 20As(CH 3 ) 2 . OH. It is also obtained by the action of mercuric oxide upon cacodylic oxide : > + 2H S + H ' = 2As (CH 3 ) 2 . OH + 2Hg. As(CH 3 ) It is easily soluble in water, is odorless, and melts at 200, with decomposition. Hydriodic acid reduces it to cacodyl iodide, As(CH 3 ) 2 I. Hydrogen sulphide changes it to cacodyl sulphide. PC1 5 converts it into dimethyl arsentrichloride, (CH 3 ) 2 Asd 3 , which, like an acid chloride, regenerates cacodylic acid with water. As(CH 3 ) 2 Cacodyl, As 2 (CH 3 ),=| , diarsentetramethyl, is formed by heating the . As(CH 3 ) 2 chloride with zinc filings in an atmosphere of carbon dioxide: As(CH 3 ) 2 2 HC1^ Cl . As(CH 3 ) 2 Zn As(CH 3 ) 2 ^ Cl . As(CH 3 ) 2 ^ As(CH 3 ) 2 ' It is a colorless liquid, insoluble in water. It boils at 170, and solidifies at 6. Its odor is frightfully strong, and may induce vomiting. . Cacodyl takes fire very readily in the air and burns to As 2 O 3 , carbon dioxide and water. It yields cacodyl chloride with chlorine and the sulphide with sulphur. Nitric acid converts it into a nitrate, 'As(CH 3 ) 2 . O . NO 2 . As(C 2 H 5 ) 2 Ethyl Cacodyl, | , diethylarsine, is formed together with triethylarsine As(C 2 H 5 ) 2 on heating sodium arsenide with ethyl iodide. It boils at 185-190, and takes fire in the air. It oxidizes to diethyl arsinic acid, (C 2 H 5 ) 2 AsO . OH. TERTIARY ARSINES. The tertiary arsines are formed by the action of the zinc alkyls upon arsenic trichloride and by heating the alkyl iodides with sodium arsenide. Cacodyl, formed simultaneously, is separated by fractional distillation. Trimethylarsine, (CH 3 ) 3 As, and Triethylarsine, (C 2 H 5 ) 3 As, are liquids with very disagreeable odor. With oxygen they yield Trimethyl arsenoxide, (CH 3 ) 3 AsO, and Triethyl arsenoxide, (C 2 H 5 ) 3 AsO. These bodies correspond to triethylamine oxide (p. 172) and triethyl phosphine oxide (p. 175) ; with sulphur they yield trimethyl- and triethyl arsine sulphide, As(C 2 H 5 ) 8 S; and with Br 2 and I 2 they form trinuthyl arsine bromide, As(CH 3 ) 3 Br 2 , and triethyl arsine iodide, As(C 2 H 5 ) 3 I 3 . Quaternary Alkyl Arsonium Derivatives. Tetramethyl Arsonium Iodide, As(CH 3 )J, and tetra-ethyl arsonium iodide, As(C 2 H 5 )J, are obtained by the union of trimethyl arsine and triethyl arsine with methyl iodide and ethyl iodide. Both bodies crystallize, and correspond to the tetra-alkyl ammonium and phosphonium ALKYL COMPOUNDS OF BISMUTH. 179 (pp. 1 68, 174). Like the latter, they are changed by moist silver oxide to hydroxides : Tetramethyl Arsonium Hydroxide, As(CH 3 ) i OH, and Tetra-ethyl Arsonium Hydroxide, As(C 2 H 5 ) 4 OH. These are crystalline, deliquescent bodies. They show a strong alkaline reaction. 8. ALKYL DERIVATIVES OF ANTIMONY. The derivatives of antimony and the alkyls are perfectly analogous to those of arsenic ; but those containing one and two alkyl groups do not exist. We are indebted to Lowig and to Landolt for our knowledge of them. Tertiary Stibines are produced like the tertiary arsines : (1) By the action of alkyl iodides upon potassium or sodium antimonides ; (2) By the interaction of zinc alkyls and antimony trichloride. Trimethylstibine, Sb(CH 3 ) 3 , antimony trimethyl, boils at 81; its sp. gr. at 15 is 1.523, and Triethylstibine or Stibethyl, Sb (C 2 H 5 ) 3 , boiling at 159, are liquids which take fire in the air, and are insoluble in water. In all their reactions they manifest the character of a bivalent metal, perhaps calcium or zinc. With oxygen, sulphur, and the halogens, they combine energetically and decompose the concen- trated haloid acids, expelling their hydrogen : Sb(C 2 H.) 3 + 2HC1 = Sb(C 2 H 5 ) 3 Cl 2 + H 2 . Triethyl Stibine Oxide, Sb(C 2 H 5 ) 3 O, is soluble in water, which is also true of Triethylstibine Sulphide, Sb(C 2 H 5 > 3 S, consisting of shining crystals. Its solution behaves somewhat like a calcium sulphide solution. It precipitates sulphides from solutions of the heavy metals with the formation of salts of triethylstibine. Quaternary Stibonium Compounds, prepared from tertiary stibines by the addition of alkyl iodides, are changed by moist silver oxide into tetra-alkyl stibonium hydrox- ides. Tetramethyl and Tetraethyl stibonium iodide, Sb(C 2 H 5 )J, as well as Tetra- methyl and Tetraethyl stibonium hydroxide, (C 2 H 5 )^SbOH, resemble the corres- ponding arsenic derivatives very much in their properties. 9. ALKYL COMPOUNDS OF BISMUTH. These arrange themselves with those derived from antimony and arsenic ; but in accordance with the complete metallic nature of bismuth, we do not meet any com- pounds here analogous to stibonium or arsonium. Further, in trialkyl derivatives the alkyl groups are less intimately united with the bismuth than they are with arsenic and antimony in their corresponding derivatives. Tertiary bismuthides result from (i) the action of alkyl iodides upon potassium bismuthide ; (2) the interaction of zinc alkyls and bismuth tri-bromide. Bismuth-Trimethyl, Bi(CH 3 ) 3 , and Bismuth-Triethyl, Bi(C 2 H 5 ) 3 , are liquids. They can be distilled without decomposition under diminished pressure. They ex- plode when heated at the ordinary pressure (B. 20, 1516; 21, 2035). Bismuth trimethide is changed by hydrochloric acid to BiCl 3 and methane. The tri-ethide is spontaneously inflammable. It unites with iodine to Bismuth Diethyl Iodide, Bi- (C 2 H 5 ) 2 I ; and with mercuric chloride to Bismuth-ethyl Chloride, Bi(C 2 H 5 )Cl 2 : Bi(C 2 H 5 ) 3 + 2HgCl 2 =Bi(C 2 H 5 )G 2 + 2Hg(C 2 H 5 )Cl. l8o ORGANIC CHEMISTRY. From the alcoholic solution of the iodide the alkalies precipitate Bismuth-ethyl oxide, Bi(C 2 H 5 )O an amorphous, yellow powder, which takes fire readily in the air. The nitrate, Bi(C 2 H 6 )<^Q'.,^-Q 2 , is produced by adding silver nitrate to the iodide. 10. BORON ALKYL COMPOUNDS. These are formed by the action of zinc alkyls upon (l) boron trichloride, (2) boric ethyl ester (p. 147) (Frankland, A. 124, 129) : 2B(O.C 2 H 5 ) 3 + 3 Zn(C 2 H 5 ) 2 . 2B(C 2 H 5 ) 3 + 3 (C 2 H 5 . O) 2 Zn. Trimethyl Borine is a gas. Triethylborine, or Borethyl, B(C 2 H 5 ) 3 , boils at 95. Both ignite in contact with the air and possess an extremely penetrating odor. When heated together with hydrochloric acid, ethyl borine decomposes into diethylborine chloride and ethane : B(C 2 H 5 ) 3 + HC1 = B(C 2 H 5 ) 2 C1 + C 2 H 6 . Slowly oxidized in the air, triethylborine passes into the diethyl ester of ethyl boric acid or Boron Etho-diethoxide, B(C 2 H 5 )(O.C 2 H 5 ) 2 , boiling at 125; water de- composes it into ethyl boric acid, C 2 H 5 . B(OH) 2 . II. SILICON ALKYL COMPOUNDS. Silicon is the nearest analogue of carbon. Its similarity to the latter shows itself very strongly in its -derivatives with the alcohol radicals, which in many respects resemble the correspondingly constituted paraffins (Friedel ; Crafts; Ladenburg, A. 203, 241). As early as 1863 Wohler directed attention to the analogy existing between the carbon and silicon compounds. Silicon Tetramethide, Si (CH 3 ) 4 , corresponds to Tetramethyl Methane, C(CH 3 ) 4 . Silicon Tetraethide, Si(C 2 H 5 ) 4 , corresponds to Tetraethyl Methane, C(C 2 H 5 ) 4 . They are produced like the alkyl borines when zinc alkyls act upon (1) Silicon halogen compounds; (2) Upon esters of silicic acid. Silicon-methyl, Si(CH 3 ) 4 , from SiCl 4 and zinc methyl, boils at 30. Silicon-ethyl, Silicon-tetraethide, Si(C 2 H 5 ) 4 , Silicononane, from SiCl 4 and Zn(C 2 H 5 \, by the action of chlorine, forms a substitution f fp TT \ product, Si \ ^ IT p?, silicononyl chloride. Potassium acetate changes TIN ALKYL COMPOUNDS. l8l this to the acetic ester of silicononyl alcohol, which alkalies decom- pose into acetic acid and silicononyl alcohol : Silicononane, Silicononyl Chloride, Silicononyl Alcohol. B. P. 153 B. P. 185 B. P. 190. Silicon Hexethyl, or Hexethyl-silicoethane, Si 2 (C 2 H 5 ) 6 , from zinc ethyl and Si 2 I 6 , boils from 250-253. IV Triethylsilicon Ethylate, (C 2 H 5 ) 3 Si.O.C 2 H 5 , boils at 153. Diethylsilicon-diethylate, (C 2 H 5 ) 2 Si.(O.C 2 H 5 ) 2 , boils at 155.8. Ethylsilicon-triethylate, (C 2 H 5 )Si(O.C 2 H 5 ) 3 , is a liquid with a camphor-like odor, boiling at 159. These three compounds are produced when zinc ethide acts upon silicic ethyl ester, Si(OC 2 H 5 ) 4 (p. 147). Acetic anhydride converts triethyl silicon ethyl ester into an acetic ester. When this is saponified by caustic potash, it yields Triethylsilicon hydroxide or Triethyl silicol, (C 2 H 5 ) 3 Si OH, corresponding in constitution to Triethyl carbinol. Acetyl chloride changes diethyl silicon diethyl ester into Diethylsilicon chloride, (C 2 H 5 ) 2 SiCl 2 , boiling at 148. Water transposes it into dietJiylsilicon oxide, (C 2 H-) 2 - Si . O, corresponding to diethyl ketone in composition. With acetyl chloride ethyl silicon triethyl ester forms ethyl silicon trichloride, (C 2 H 5 )SiCl 3 . This liquid fumes strongly in the air, boils at about 100, and when treated with water passes into ethyl silicic acid, (C 2 H 5 )SiO.OH (Silico-propionic acid), which is analogous to propionic acid, C 2 H 3 .CO.OH, in constitution. It is a white, amorphous powder, which becomes incandescent when heated in the air. With the corresponding propionic acid it only shares the property of being an acid. TABLE. (C 2 H 5 ) 3 SiOH, Triethyl Silicol corresponds to (C 2 H 5 ) 3 C . OH, Triethyl' Carbinol. (C 2 H 5 ) 2 SiO, Diethyl Silicon Oxide corresponds to (C 2 H 5 ). 2 CO, Diethyl Ketone. C 2 H 5 . SiO . OH, Silico-propionic Acid corresponds to C 2 H 5 . COOH, Propionic Acid. 12. GERMANIUM ALKYL DERIVATIVES. The compounds of germanium form the transition from those of silicon to those of tin. Germanium-Ethide, Ge(C 2 H 5 ) 4 , is formed when zinc ethide acts upon ger- manium chloride. It is a liquid with a leek-like odor. It boils at 160 (Cl. Winkler, J. pr. Ch. [2] 36, 204). 13. TIN ALKYL COMPOUNDS. In addition to the saturated derivatives with four alkyls, tin is also capable of uniting with three and two alkyls, forming : Sn(C 2 H 6 ) 3 Sn(C 2 H 5 ) 2 Sn(C 2 H 5 ) 4 | || or Sn(C 2 H 5 ),. Sn(C 2 H 5 ) 3 SnfC 2 H 5 ) 2 Tin Tetraethyl Tin Triethyl Tin Diethyl. 1 82 ORGANIC CHEMISTRY. The alkyl derivatives of tin were studied by Lowig, Cahours, Ladenburg, and others. The reactions resorted to in order to combine tin with alkyls are the same as were employed with arsenic, antimony, and other elements. (l) The action of zinc alkyls upon stannic chloride, when Sn(CH 3 ) 4 and Sn(C 2 H 5 ) 4 are produced. (2) The action of alkyl iodides upon tin-sodium (tin alone or tin-zinc). When the alloy con- tains a great deal of sodium, Sn(C 2 H 5 ) 3 is produced, but when comparatively little sodium is present the chief product is Sn(C 2 H 5 ) 2 T 2 . Sodium abstracts iodine from both of the primarily formed iodides with the formation of Sn 2 (C 2 H 5 ) 4 and Sn 2 (C 2 - H 5 ) 6 . These can be separated by means of alcohol, in which the latter is insoluble. Tin Tetramethyl, Sn(CH 3 ) 4 , boils at 78. Tin Tetraethyl, Stannic Ethide, Sn(C,H 5 ) 4 , boils at 181 and possesses a specific gravity of 1.187 a * 2 3- Both are colorless, ethereal smelling liquids, insoluble in water. By the action of the halo- gens the alkyls are successively eliminated. Hydrochloric acid acts similarly: Sn(C 2 H 5 ) 4 + I, =Sn(C 2 H 5 ) 3 I + C 2 H 5 I, etc. Sn(C 2 H 5 ) 4 -f HC1 = Sn(C 2 H 5 ) 3 Cl -f- 2C 2 H 6 , etc. The alkyl groups are not so firmly united in the zinc alkyls as they are in the alkyls of silicon. Tin Triethyl Iodide, Sn(C 2 H 5 ) 3 T, boils at 231, and has a specific gravity of 1.833 at 22 - Ti H triethyl chloride, Sn(C 2 H 5 ) 3 Cl, boils at from 208-210, and has a specific gravity of 1.428. Alcohol is a solvent for both. When either one is acted upon by silver oxide or caustic potash, there is produced : Tin Triethyl Hydroxide, Sn(C 2 H 5 ) 3 . OH, melting at 66 and boiling at 272. It volatilizes along with the steam. It is sparingly soluble in water, but dissolves readily in alcohol and ether. It reacts strongly alkaline, and yields crystalline salts with the acids, e. g., Sn(C 2 H 5 ) 3 . O . NO 2 . When the hydroxide is heated for some time to almost the boiling temperature, it breaks down into water and tin triethyl oxide, n } r , 2 ri 5 N 3 ^O, an oily liquid, which in the presence of water at once regenerates the n^ 2 ri 5 j 3 hydrate. Tin Triethyl, Sn 2 (CoH 5 ) 6 (see above), is a liquid, of mustard-like odor, insolu- ble in alcohol, but readily soluble in ether. It distils with slight decomposition at 265-270. It combines with oxygen, forming tin-triethyl oxide, c/r^u \ 3 !>O, sn(L, 2 n 5 ) 3 and with iodine yields tin-triethyl iodide, 2Sn(C 2 H 5 ) 3 I. Tin Diethyl, Sn 2 (C 2 H 5 ) 4 , or Sn(C 2 H 5 ) 2 , is a thick oil, decomposing when heated into Sn(C 2 H 5 ) 4 and tin. It combines with oxygen and the halogens. Tin Diethyl Chloride, Sn(C 2 H 5 ) 2 Cl 2 , melts at 85 and boils at 220. The iodide, Sn;C 2 H 5 ) 2 T 2 , fuses at 44.5, and boils at 245. Ammonium hydroxide and the alkalies precipitate from aqueous solutions of both the halogen compounds : Tin Diethyl Oxide, Sn(C 2 H 5 ) 2 O, a white, insoluble powder. It is soluble in excess of alkali, and forms crystalline salts with the acids, e. g., Sn(C 2 H 5 ) 2 C<^_ might be expected, then, except in very rare instances, water separates, an anhydride is produced, and double union between carbon and oxygen follows, with the production of the carbonyl group >C O. Ethers, however, of diacid alcohols, of the orf ho- aldehydes and ortho- ketones, can exist, e. g.: CH 3 . CH(O . C 2 H,) 2 and CH 3 . C(O . C,H 5 ) 2 . CH 3 . ' The following principal methods of formation are common to alde- hydes and ketones : (i) Oxidation of the alcohols, whereby the primary alcohols change to aldehydes and the secondary to ketones (p. in). I 88 ORGANIC CHEMISTRY. In this oxidation an oxygen atom pushes itself between a hydrogen atom and the carbon atom to which the hydroxyl group is joined. In the moment of formation the expected diacid alcohol splits off water, and its anhydride results, an alde- hyde or ketone : CH 8 -CH 2 OH -- -> (CH 3 . CH<) _ _^ CH3 , C ^O + ^ Primary Alcohol Cannot exist Aldehyde Sec. Propyl Alcohol Cannot exist Acetone. By further oxidation the aldehydes become acids the hydrides of the acid radicals, while the ketones are decomposed. Conversely, aldehydes and ketones again become primary and secondary alcohols by an addition of hydrogen : CH 3 . CHO + H 2 = CH 3 . CH 2 . OH Aldehyde Ethyl Alcohol 8 Acetone Isopropyl Alcohol. Because the aldehydes and ketones manifest an additive power with reference to hydrogen, they may be compared with compounds con- taining doubly linked carbon atoms, which also, by a dissolution of their double union, can add hydrogen. Compounds of this class having in their molecules carbon atoms which are doubly (or trebly) united, are in the more restricted sense called " unsaturated carbon derivatives" (p. 79). This idea may be extended, and all carbon derivatives having atoms of other elements in double or treble union with carbon, may be considered as " unsaturated" From this stand- point the aldehydes and ketones are unsaturated bodies (p. 38), and in fact most of the reactions of these two classes are due to the addi- tive power of the unsaturated carbonyl group. (2) The dry distillation of a mixture of the calcium, or better, barium salts of two monobasic fatty acids. Should in this case one of the acids be formic acid, aldehydes are produced : H . COO, r , CH 3 . OXX r CH, . COH , H . COO >Ca + CHJJ . COO> Ca = CH 3 . COH Calcium Formate Calcium Acetate Acetaldehyde. It is the hydrogen of the formate which reduces the acid. In all other instances ketones result, and they are either simple, with two similar alkyls, or mixed, with two dissimilar alkyls : . r ~ p 3 ^ u * ca Acetone CH 3 CH . COO CH 3 . ^p i 25 ^p _ | 8 ^fyN , CH 3 . COO> Ca + C 2 H 5 COO >Ca - 2 CH 3 > Calcium Propionate Ethyl Methyl Ketone. On extending this reaction to the calcium salts of adipic, pimelic and suberic acids, cyclo-paraffin ketones are produced. ALDEHYDES OF THE LIMIT SERIES. 189 2A. ALDEHYDES OF THE LIMIT SERIES, PARAFFIN ALDE- HYDES, Cn The aldehydes exhibit in their properties a gradation similar to that of the alcohols. The lower members are volatile liquids, soluble in water, and have a peculiar odor, but the higher are solids, insoluble in water, and cannot be distilled without decomposition. In general they are more volatile and dissolve with more difficulty in water than the alcohols.^ In chemical respects the aldehydes are neutral sub- stances. Formation. (i) By the oxidation of primary alcohols, when the CH 2 . OH group becomes CHO (p. 188). The above oxidation may be effected by oxygen ; or air in presence of platinum sponge. It takes place more readily on warming the alcohols with potassium dichro- mate (or MaO 2 ) and dilute sulphuric acid (B. 5, 699). Chlorine acts similarly in that it first oxidizes the primary alcohols, but then substitutes the alkyl groups of the alde- hydes which have been formed (p. 197). (2) By heating the calcium salts of fatty acids with calcium formate. This operation, when working with aldehydes which volatilize with difficulty, should be carried out under diminished pressure (p. 63) (B. 13, 1413). (3) By the action of nascent hydrogen (sodium amalgam, or, better, sodium upon the moist ethereal solution, B. 29, R. 662) upon the chlorides of the acid radicals or their oxides, the acid anhydrides : CH 3 .COC1 + 2H = CH 3 .COH-f HC1 Acetyl Chloride Acetaldehyde CH 3 CO> + 4 H = 2CH 3 COH + H 2- Acetic Anhydride Acetaldehyde. In accordance with methods 2 and 3 the aldehydes may be viewed as hydrides of the acid radicals. (4) By heating the aldehyde chlorides with water alone, or with water and lead oxide. (5) By the saponification of the ethereal and ester-derivatives, e. g. , acetal, CH, . CH<' / ^ r v Z TT 5 > and ethidene diacetate. CH, . CH-^,-. ' ^^ ' r-rr 3 , with sulphuric Ui.*2"5 vJ . \~\J . L^rlo acid or alkalies. From methods 4 and 5 dihydroxyl derivatives should be at first produced. These are the glycols, which, however, immediately pass into aldehydes with the simultaneous exit of water (p. 188) : CH,, (6) When the sodium salts of mononitro-parafBns, having the nitro-group attached to a terminal carbon atom, are treated with acids, paraffin aldehydes are produced (B. 29, 1223) (p. 156). (7) Aldehydes can also be obtained from many addition products (p. 191), par- ticularly the aldehyde ammonias and the alkali sulphite derivatives. 190 ORGANIC CHEMISTRY. (8) When the o-mono-carboxylic acids are treated with sulphuric acid aldehydes are formed, with a simultaneous splitting-off of formic acid or its decomposition products water and carbon monoxide : CH 3 . CH(OH)CO 2 H = CH 3 . CHO + H . COOH. Lactic Acid Acetaldehyde Formic Acid. Note. Quite frequently aldehydes occur among the decomposition products of complex carbon compounds, as the result of their oxida- tion with MnO 2 and dilute sulphuric acid, or by means of a chromic acid solution. Nomenclature and Isomerism. Empirically, the aldehydes are dis- tinguished from the alcohols by possessing two atoms less of hydrogen hence their name, suggested by Liebig (from Alkohol dehydroge- na/us), e. g., ethyl aldehyde, propyl aldehyde, etc., etc. On account of their intimate relationship to the acids, their names are also derived from the latter, like acetaldehyde, propionic aldehyde, etc. In the " Geneva nomenclature" the names of the aldehydes are formed from the corresponding saturated hydrocarbons by the addition of the suffix al ; thus ethyl- or acetaldehyde would be termed [ethanal] (p. 57). As there is an aldehyde corresponding to every primary alcohol, the number of isomeric aldehydes of definite carbon content equals the number of possible primary alcohols having the same carbon content (p. 109). The aldehydes are isomeric with the ketones, the unsatu- rated allyl alcohols, and the anhydrides of the ethylene-glycol series, containing an equal number of carbon atoms, e. g. : CH 3 .CH 2 .CHO isomeric with CH 3 .CO.CH 3 CH 2 = CHCH 2 OH CH a <*>O. Propionic Aldehyde Acetone Allyl Alcohol Trimethylene Oxide. Transformations of the Aldehydes : A. Reactions in which the carbon nucleus of the aldehydes remains the same. (i) Aldehydes, by oxidation, yield monocarboxylic acids with a like carbon content. They are powerful reducing agents : CH 3 C/ H + O = CH 3 C/ OH . Their ready oxidation gives rise to "important reactions serving for the detection and recognition of aldehydes. On adding an aqueous aldehyde solution to a weak ammoniacal silver nitrate solution, silver separates on the sides of the vessel as a brilliant mirror. Alkaline copper solutions are also reduced. A very delicate reac- tion of the aldehydes is their power of imparting an intense violet color to a fuchsine solution previously decolorized by sulphurous acid. The following is more sensitive : Add an aldehyde and a little sodium amalgam to the sodium hydroxide solution of diazobenzene sulphonic acid and a violet-red coloration is produced. (Compare further B. 14, 675, 791, 1848; 15, 1635, 1828; 16, 657; 17, R. 385.) When oxygen or air is conducted through the hot solution of an aldehyde (like paraldehyde) in alcoholic potash, an intense light-display is observed in the dark ; many aldehyde derivatives, and even grape sugar, deport themselves similarly (B. 10, 321). Aldehydes absorb oxygen from the air. The oxygen in this solution, like ozone, can liberate iodine from, a potassium iodide solution (B. 29, 1454). ALDEHYDES OF THE LIMIT SERIES. 19! (2) Nearly all the aldehydes are converted into resin by the alkalies; some are transformed into acids and alcohols (this is especially true of the aromatic aldehydes), and others into acids and glycols (see these) by alcoholic alkali solutions : 2C 4 H 9 . COH + KOH =C 4 H 9 . CO . OK + C 4 H 9 . CH 2 . OH. Amyl Aldehyde Pot. Valerate Amyl Alcohol. The ease with which the double union of the carbon -oxygen atoms is broken is the cause of a large number of addition reactions, which are in part followed by an exit of water. (3) Aldehydes, by the addition of nascent hydrogen, become pri- mary alcohols, from which they are obtained by oxidation : CH 3 . CHO + 2H = CH 3 . CH 2 OH. (4) Deportment of the aldehydes toward water and alcohols, (a) Ordinarily, aldehydes do not combine (compare p. 195 ; CH 2 (OH) 2 ) with water. The polyhalide aldehydes, e. g., chloral, bromal, butyl chloral (pp. 197, 198) do, however, have this power, and yield feeble and readily decomposable hydrates, representatives of diacid alcohols or glycols, both hydroxyl groups of which are attached to the same carbon atom : CC1 3 CH<^ CBr 3 CH<^ CH 3 . CHC1 . CC1 2 CH<^- Chloral Hydrate Bromal Hydrate Butyl Chloral Hydrate. Trichlor-ethidene Glycol (&) It is also only the polyhalide aldehydes, e.g,, chloral, which unite with alco- hols, forming aldehyde-alcoholates : CC1 3 H<^^2 A1 5 Chloral Alcoholate. (c) The ordinary aldehydes yield acetals with the alcohols at 100 (p. 200): CH 3 . CHO + 2C 2 H 5 . OH = CH 3 . CH< ' 25 -f H 2 O. Acetal or Ethidene-diethyl Ether. ($) Behavior of the aldehydes with hydrogen sulphide and mercaptans : (a] hydro- gen sulphide and hydrochloric acid convert the aldehydes into trithioaldehydes : (b) with the mercaptans the aldehydes enter into an acetal synthesis after the addition of hydrochloric acid (p. 204). (6) Aldehydes and acid anhydrides unite to esters of the diacid alcohols or gly- cols, which are not stable in an isolated condition. Indeed, the aldehydes maybe regarded as their anhydrides (pp. 188, 189) : O.C 2 H 3 Ethidene Diacetate. (7) Aldehydes unite in a similar manner with acid alkaline sul- phites, forming crystalline compounds : CH 3 . CHO + S0 3 HNa = CH 3 . CH< > 192 ORGANIC CHEMISTRY. which may be regarded as salts of oxysulphonic acids. The aldehydes may be released from these salts by distillation with dilute sulphuric acid or soda. This procedure permits of the separation and purifica- tion of aldehydes from other substances. (8) Behavior of aldehydes with ammonia, primary alkylamines, hydroxylamine, and phenylhydrazine (C 6 H 5 . NH . NH 2 ). (a) They unite directly with ammonia to form crystalline compounds, called aldehyde ammonias. These are readily soluble in water but not in ether, hence ammonia gas will precipitate them in crystalline form from the ethereal solution of the aldehydes. They are rather unstable, and dilute acids again resolve them into their components. Pyridine bases are produced when the aldehyde-ammonias are heated. (^) Aldehydes and primary amines combine, with the exit of water, to form aldehyde-imides (p. 161). (c} By an exit of water the aldehydes unite with hydroxylamine to >form the so-called aldoximes (V. Meyer, B. 15, 2778). It is very evident that at first, in these cases, there is formed an unstable intermediate product (compare chloral hydroxylamine, p. 206) corresponding to aldehyde-ammonia: - ~ H2 (d) The aldehydes deport themselves similarly with phenylhydrazine ; water separates and hydrazones (E. Fischer) result : CH 3 . CHO -f H 2 N . HN . C 6 H 5 = CH 3 . CH : N . NH . C 6 H 5 + H 2 O. These serve admirably for the detection and characterization of the aldehydes. The aldoximes and hydrazones, when boiled with acids, absorb water and revert to their parent substances. They yield pri- mary amines when reduced (p. 161). (e] The aldehydes also unite with p-amido dimethyl aniline (B. 17, 2939), with the amido-phenols and other aromatic bases (Schiff, B. 25, 2020). (9) Compounds are formed by the action of phosphorus trichloride upon aldehydes, which are converted by water into oxyalkyl-phosphinic acids, e. g., CH 3 . CH(OH)- PO(OH) 2 (B. 18, R. in). (10) Phosphorus pentachloride and phosphorus trichlor-dibromide replace the aldehyde oxygen by chlorine or bromine and yield dichlo- rides and dibromides, in which the two halogen atoms are linked to a terminal carbon atom (p. 102): CH 3 . CHO + PC1 5 = CH 3 CHC1 2 -f POC1 3 . (u) The hydrogen atoms of the alkyl groups of the aldehydes may be replaced by chlorine and bromine, as well as by iodine and iodic acid. (12) The lower members of the homologous series of the aldehydes ALDEHYDES OF THE LIMIT SERIES. 193 polymerize very readily. The polymerization of the aldehydes and thio- aldehydes depends upon the union of several aldehyde radicals, CH 3 .- CH:=, through the oxygen or sulphur atoms (A. 203, 44). This phe- nomenon will be fully treated under formaldehyde and acetaldehyde (p. 194). B. Nucleus synthetic Reactions of the Aldehydes, (i) Aldol Conden- sations. Two (or more) aldehyde molecules may unite, under proper conditions, by means of carbon linkings. Thus, aldehyde alcohols are formed from acetaldehyde : Aldol (Wiirtz) or /?-oxybutyraldehyde, CH 3 . CHOH . CH 2 . CHO (see this). Similarly, aldehyde or chloral and acetone (p. 213), aldehyde and malonic ester, unite with one another. But almost invariably the resulting oxy-derivatives split off water and pass into unsaturated bodies : aldol into crotonaldehyde, CHoCH = CH.CHO. These are nucleus-syntheses and are' often termed condensation reactions. The reagents suitable for the production of such reactions are mineral acids, zinc chloride, caustic alkalies, a sodium acetate solution, etc. Condensation reactions, in which an aliphatic aldehyde plays the role of one of the component or parent substances, will be frequently encountered. A reaction discovered by Perkin, Sr., when working with aromatic aldehydes, has been employed quite frequently to unite aldehydes and acetic acid, as well as mono-alkyl acetic acids, in such a manner that the products are unsaturated monocarboxylic acids (see nonylenic acid}. The aldehydes unite in like manner with succinic acid, forming y-lactone carboxylic acids the paraconic acids (see these). (2) Aldehydes can also unite with zinc alkyls. This union is accompanied by the breaking down of the double union between carbon and oxygen. The action of water on the addition product produces a secondary alcohol (p. 114). Olefine alcohols result by the use of allyl iodide and zinc (p. 131). (30) Aldehydes also combine with hydrogen cyanide, yielding oxy- cyanides or cyanhydrins the nitriles of a oxy-acids (see these), which will be discussed after the a-oxy-acids, and which can be obtained from them by means of hydrochloric acid : CN HC1 C0 2 H CH, . CHO + CNH = CH, . CH( iOr->- CH, CH^ X OH Lactic Acid X OH (6} Aldehydes and ammonium cyanide combine ; water separates, and the nitriles NH of a-aniido-acids, e g , CH 3 . CH<^^ 2 , result. When treated with hydrochloric acid they yield amido-acids (see these). The same amido-nitriles are produced by the action of CNH upon the aldehyde ammonias, and from the oxy-cyanides and ammo- nia. Cyanides of a-anilido- and a-phenyl hydrazido-acids are formed by the addi- tion of prussic acid to the aliphatic aldehyde-anilines and aldehvdepkenylhydrazones (B. 25, 2020). Formic Aldehyde, Methyl Aldehyde [Methanal] H - C ^H, was dis- covered by A. W. Hofmann, and was until recently only known in aque- ous solution and in vapor form. It may, as was shown by Kekule, be condensed by strong cooling to a colorless liquid, boiling at 21, and having at 80 the sp. gr. 0.9172 ; at 20, the sp. gr. 0.8153. 17 194 ORGANIC CHEMISTRY. Liquid formaldehyde changes slowly at 20, rapidly at the ordi- nary temperature, with a snapping noise, into trioxymethylene (CH 2 O) 3 (B. 25, 2435). This polymeric modification was known before the simple formaldehyde. It resolves itself into the latter on the applica- tion of heat. Formaldehyde possesses a sharp, penetrating odor, and destroys bacteria of the most varied sort. It is applied under the name of formaline, either in solution or as a gas, for disinfecting purposes (B. 27, R. 757, 803; 28, R. 938; 29, R. 178, 288, 426). Methods of Formation. (i) It is produced if the vapors of methyl alcohol, mixed with air, are conducted over an ignited platinum spiral or ignited copper gauze (J. pr. Ch. 33, 321; B. 19, 2133; 20, 144; A. 243, 335). Lamps have been constructed for the production of formaldehyde. Methyl alcohol is oxidized in them in the presence of a platinum wire gauze. Compare B. 28, 261. (2) When chlorine and bromine act upon methyl alcohol, formic aldehyde is produced (B. 26, 268), and is converted by them in sunlight into haloid acids and carbon dioxide (B. 29, R. 88). (3) It also arises in small quantity in the distillation si calcium formate. (4) By the digestion of methy/al, CH 2 (OCH 3 ) 2 (p. 200) with sulphuric acid (B. 19, 1841). Mercklin and Losekann, in Seelze, near Hannover, manufacture formaldehyde tech- nically from methyl alcohol by a method not well known, and offer its 40 per cent, solution to trade, together with numerous other derivatives of formaldehyde. The quantity of formic aldehyde is determined by its conversion into hexamethyleneamine, (CH 2 ) 6 N 4 (B. 16, 1333; 22, 1565, 1929; 26, R. 415). In the presence of lime formaldehyde condenses to a-acrose or (d -j- 1) fructose (see this). It yields penta- erythrite C(CH 2 OH) 4 (see this) (B. 26, R. 713) with acetaldehyde. Formic alde- hyde condenses in like manner with ketone-like bodies. In the various reactions of formaldehyde its oxygen unites with two hydrogen atoms of the reacting body to yield water. It is immaterial whether the hydrogen is in union with carbon, nitrogen, or oxygen. The products are diphenylmethane deriv- atives, methylene aniline, and formals of polyhydric alcohols (A. 289, 20). Polymeric Modifications of Formaldehyde. The concentrated aqueous solution of formic acid not only contains volatile CH 2 O, but also the hydrate CH 2 <^QTT i. CH 3 . CH< H - --3 .<-- II IV (CH 3 . CH< | ' &{Ja) a> CH.C1 . CH< &H ft - HC1 > CH 2 C1 . CH< ' C * H * U -S H 5 I U.JJjtli CHC1,.CH HCC1, + CCl 3 CHC Chloralide. Chloral Hydrate, Trichlorethidene Gfycol, CC1 3 .CH<^, results from the union of chloral with water. It is technically prepared on a very large scale. It consists of large monoclinic prisms, fusing at 57 and distilling at 96-98. The vapors dissociate into chloral and water. Chloral hydrate dissolves readily in water, possesses a peculiar odor and a sharp, biting taste ; when taken internally it produces sleep, which fact was discovered in 1869 by Liebreich (B. 2, 269). It occurs in urine as urochloralic acid (see this). Concentrated sulphuric acid resolves the hydrate into water and chloral. It reduces ammoniacal silver solutions and when oxidized with nitric acid yields trichloracetic acid. In chloral hydrate we encounter the first example of a body which, contrary to the rule, contains two hydroxyl groups attached to the same carbon atom, without having the immediate spontaneous exit of water. Chloral Alcoholate, CC1 3 . CH CH 2 C1.CH 2 .CHO ^^> CH 2 C1.CH 2 .CO 2 H Acrolein /3-Chlorpropionic Aldehyde /3-Chlorpropionic Acid TT/^J .- CH..CH = CH.CHO - -> CH 3 .CHC1.CH 2 CHO -> CH 3 .CHC1.CH 2 .CO 2 H Crotonaldehyde 0-Chlorbutyraldehyde 0-Chlorbutyric Acid CH 3 .CH = CC1.CHO -^> CH 3 .CHC1.CC1 2 .CHO - > CH 3 .CHC1.CC1 2 CO 2 H a-Chlorcrotonaldehyde Butylchloral Trichlorbutyric Acid. 2. ETHERS AND ESTERS OF METHYLENE AND ETHIDENE GLYCOLS. In the introduction to the aldehydes (p. 188) it was explained that these bodies could be regarded as anhydrides (see chloral hydrate, p. 198) of glycols, only capable of existing in exceptional cases. In the latter the two hydroxyl groups were linked to the same terminal carbon atom. Stable ethers and esters of these hypo- thetical glycols are, however, known. These hypothetical glycols might also be designated orthoaldehydes, because they bear the same relation to the aldehydes that the hypothetical orthocarbonic acids sustain to the carboxylic acids : /OH .OH CH 2 CH 3 CH(O.C 2 H 5 ) 2 + 2H 2 O. (2) When aldehydes are heated with the alcohols alone to 100 ; and from tri- oxymethylene and alcohols on the addition of ferric chloride (1-4 per cent.) (B. 27, R. 506). (3) By the action of gaseous HC1 upon a mixture of alcohol and aldehyde, chlor- hydrin (see ethylene glycol) being the first product : CH 3 CHO+C 2 H 5 OH (4) By the action of alcoholates upon the corresponding chlorides, bromides and iodides. On heating the acetals with alcohols, the higher alkyls are replaced by the lower (A. 225, 265). When the acetals are digested with aqueous hydrogen chloride they are resolved into their constituents. They dissolve readily in alcohol and in ether, but with difficulty in water. Methylal, Methylene-dimethyl Ether, Formal, CH 2 (OCH 3 ) 2 , boils at 42 and has the sp. gr. 0.855. It ' s an excellent solvent for many carbon compounds. Methylene-dimethyl Ether, CH 2 (OC 2 H 5 ) 2 , boils at 89. For the higher methylals see B. 20, R. 553 ; 27, R. 507. Ethidene-dimethyl Ether, Dimethyl Acetal, CH 3 CH(OCH 3 ) 2 , boils at 64. Acetal, ethidene-diethyl ether, CH 3 CH(OC 2 H 5 ) a , boils at 104. Its 'sp. gr. is 0.8314 at 20. It is produced in the process of brandy distillation. It is quite stable towards the alkalies, while dilute acids readily break it down into aldehyde and alcohol (B. 16, 512). Chlorine acting upon acetal produces (1) Monochloracetal, CH C1 . CH(O . C 2 H 5 ) 2 , boiling at 157 (B. 24, 161). It also results from Dichlor- ether', CH 2 C1 . CHC1 . OC 2 H 5 , and alcohol or sodium ethyl- ate (B. 21, 617). (2) Dichloracetal, CHC1 2 . CH(O. C 2 H 3 ) 2 , boiling at 183-184. Alcohol and chlorine yield Trichloracetal, CC1 S . CH(OC 2 H 5 ),, boiling at 197. Monobromacetal, CH 2 BrCH(()C 2 H 5 ), 2 , boiling at 170, is produced from acetal, bromine and CaCO 3 (B. 25, 2551). Sulphuric acid decomposes the chlorinated acetals into alcohol and chlorinated aldehydes (p. 198). DIHALOGEN ALDEHYDES AND ALDEHYDE HALOHYDRINS. 2OI B. Dihalogen Aldehydes and Aldehyde Halohydrins, their Alkyl Ethers and Anhydrides. In describing the dihalogen substitution products of the paraffins it was indicated that compounds in which two halogen atoms occur joined to the same terminal carbon atom bear an intimate genetic relation to the aldehydes, and are therefore called aldehyde dihaloids. If these compounds be referred to the glycols containing two hydroxyl groups attached to the same terminal carbon atom, i.e., the hypothetical ortho-aldehydes, i hen the aldehyde haloids are the neutral haloid esters of these glycols. Between the ortho-aldehydes and the aldehyde haloids stand the monohaloid esters, the aldehyde halohydrins, isomeric with the monohaloid esters of the true glycols, the glycol halohydrins, but only known in the form of their alkyl ethers, the a-mono- haloids, ordinary ethers and their anhydrides, the symmetrical a-disubstituted, ordinary ethers : (CH / QH CH 3 (CH 2 < H ) .OR (CH( ) I X C1 ' CH 3 OCH CH / I CH 3 OC 2 H 5 Cl ^CHCl.CH, CHCL \ I X CHC1 . CH 3 CH 3 The genetic relations of the aldehyde haloids to the aldehydes consist in the formation of aldehyde chlorides from the aldehydes by means of PC1 5 , and the transposition of the aldehyde chlorides when heated to 100 with water. I. Aldehyde Dihaloids. The boiling points, melting points and specific gravities of some of the simple aldehyde dihaloids are given in the appended table. The inclosed numbers after the boiling points indicate diminished pressure: Name. Formula. M. P. B. P. Sp. Gr. Methylene Chloride, . . CH 2 C1 2 _ 4 I i-37 ( o) Methylene Bromide, . . CH 2 Br 2 98 2.54 ( o) Methylene Iodide, . . . CH 2 I 2 + 4 150 (330) 3-28 (15) Ethidene Chloride, . . . CH 3 CHC1 2 5 8 1.17 (20) Ethidene Bromide, . . . CH 3 CHBr 2 110 2.02 (20) Ethidene Iodide, .... Propidene Chloride, . . CH 3 CHI 2 CH 3 . CH 2 CHC1 2 I2 7 (I 7 I) 86 2.84 ( o) 1. 16 (14) Methylene Chloride is formed from CH 3 C1 and Cl, and by the reduction of chloroform by means of zinc in alcohol. Methylene Bromide results on heating CH 3 Br with bromine to 180, and by the action of trioxymethylene upon aluminium bromide. Methylene Iodide is produced when iodoform is reduced with HI, or better, with arsenious acid and sodium hydroxide (Klinger). It is characterized by a high specific gravity; chlorine and bromine change it to methylene chloride and bromide (compare ethylene, p. 90). Ethidene Chloride, Aldehyde Chloride, is produced (l) from aldehyde by the action of PC1 5 , (2) from vinyl bromide by means of hydrogen bromide, and (3) by treating copper acetylide with concentrated hydrochloric acid (A. 178, ill) (compare ethylene, p. 90). Ethidene Bromide is obtained by the action of PCl 3 Br 2 upon aldehyde (B. 5, 289). Ethidene Iodide is obtained from acetylene and hydrogen iodide (B. 28, R. 1014). 202 ORGANIC CHEMISTRY. 2. Alkyl Ethers of the Aldehyd Halohydrins, a-Monohaloid Ethers These result from the action of alcohols and haloid acids upon the aldehydes. Alcohols or alcoholates readily convert them into acetals. Monochlortnethyl Ether, CH,- CH 2 SO 2 , and Trimethylene Disulphone-sulphide, CH 2 S, do not melt at 340. This is also true of Triethidene Trisulphone! [CH,CHSO 2 ] 3 (B. 25, 248). The two isomeric trithioacetaldehydes yield Triethidene Disulphone-sulphide, CH 3 . CH . S ' melting at228 ~ 2 3 l0 - " The isomerism of the trithio- aldehydes vanishes in their oxidation products" (B. 26, 2074; 27, 1667). Thialdin, CH, CH<| ' CH(CH 3 )> NH ' meltin g at 43' is P roduced b 7 the action of NH 3 upon a-trithioacetaldehyde (B. 19, 1830), and of H 2 S upon aldehyde- 204 ORGANIC CHEMISTRY. ammonia (A. 61, 2). It yields ethidene disulphonic acid (see below) by oxidation. Methyl Thialdin, (C 2 H 4 ) 3 S 2 (NCH 3 ), melts at 79 (B. 19, 2378). B. Mercaptals or Thioacetals and their Sulphones. The thioacetals, corresponding to the acetals, are called mercaptah. They are formed (l) from alkyl iodides and alkali mercaptides ; (2) by the action of HC1 upon the aldehydes and mercaptans. They are oils with very unpleasant odors, and are oxidized by KMnO 4 to sulphones : Methylene Mercaptal, CH 2 (SC 2 H 5 ) 2 , boils at about 180. Ethidene Mercap- tal, ethidene dithioethyl, dithioacetal, CH 3 . CH . (SC 2 H 5 ) 2 , boils at 186. Propi- dene Mercaptal, CH 3 . CH 2 . CH(SC 2 H 5 ) 2 , boils at 198. In the sulphones of the mercaptals the methylene hydrogen (see above) is replace- able by alkali metal. Mono- and dialkylized sulphones can be prepared from these alkali derivatives. Again, the dialkylized sulphones may be obtained from the mer- captols (p. 218); sulphonal belongs to this class. Methylene Diethyl Sulphone, CH 2 (SO 2 C 2 H 5 ) 2 , melting at 104, is readily soluble in water and in alcohol. It is formed in the oxidation of orthothioformic ethyl ether (see this). Ethidene Diethyl Sulphone, CH 3 CH(SO 2 C 2 H 5 ) 2 , melts at 75 and boils without decomposition at about 320. C. Oxysulphonic Acids and Disulphonic Acids of the Aldehydes. The alkali salts of the oxysulphonic acids crystallize well. They decompose quite easily and are formed by the action of the alkali bisulphites upon the aldehydes. Acids decompose them into aldehydes and SO 2 . The only stable acid is Methylenehydrin Sulphonic Acid, Oxymethylene Sulphonic Acid, CH 2 (OH)SO 3 H, which is formed together with Oxymethylene Disulphonic Acid, CH(OH)(SO 8 H) 1 , and Methine Trisulphonic Acid, CH(SO 3 II) 3 , by the action of fuming sulphuric acid upon methyl alcohol and subsequent boiling of the product with water. Methionic Acid, of the disulphonic acids of the aldehydes, has long been known : Methylene Disulphonic Acid, CH 2 . (SO 3 H) 2 , Methionic Acid, is produced when fuming sulphuric acid acts upon acetamide, acetonitrile, lactic acid, etc. It is most conveniently made by saturating fuming sulphuric acid with acetylene (from calcium carbide) . In this instance it is most certainly due to the decomposition of acetaldehyde-disulphonic acid, an intermediate product : CH : CH 3 > OCH . CH(SO 3 H) 2 - -> CH a (SO 3 H) 2 f CO. There is simultaneously formed another sulpho-acid, richer in carbon. It can easily be separated from this by means of its sparingly soluble barium salt. (Privately communicated by G. Schroeter.) Methionic acid crystallizes in deliquescent needles. It is not decomposed by boiling nitric acid. CH 2 (SO 3 ) 2 Ba-(- 2H 2 Oconsists of pearly leaflets, dissolving with difficulty in water. Ethidene Disulphonic Acid, CH 3 . CH(SO 3 H) 2 , is produced when thialdin is oxidized with KMnO 4 (B. 12, 682). The hydrogen of the methine group in Ethidene Disulphonic Acid Ethyl Ester, CH 3 . CH(SO 3 C 2 H 5 ) 2 , can be replaced by sodium by means of sodium alcoholate, and then by alkyls, just as was done in the case of the sulphones (p. 203) and the alkyl malonic esters (see these) (B. 21, 1550). 4. NITROGEN DERIVATIVES OF THE ALDEHYDES. A. Nitro-Compounds. Brom-nitrometkane, and l,l-brom-nitroethane and propane, as well as 1,1-dinitro-paraffins, which have been previously described, must be regarded as nitrogen-containing aldehyde derivatives. NITROGEM DERIVATIVES OF THE ALDEHYDES. 205 B. Ammonia- and Monalkylamine Aldehyde Derivatives (p. 192). While ammonia adds itself to acetaldehyde and its homologues, forming aldehyde ammonias or amido-alcohols, e. g., CII 3 . CH^^rr 2 , when it comes in contact with formalde- hyde it immediately produces Hexamethylenetetramine, (CH 2 ) 6 N 4 , discovered in 1860 by Butlerow. Under the name of formin it is used as a solvent for uric acid. It is very soluble in water. It crystallizes from alcohol in brilliant rhombohedra. It sublimes without decom- position in a vacuum. It is again resolved into CH 2 O and ammonia when distilled with sulphuric acid. It is a monacid base, but shows no reaction with litmus (B. 22, 1929). It combines with the alkyl iodides (B. 19, 1840). (Consult further B. 26, R. 238.) Efforts have been made to ascertain its molecular weight by the analysis of its salts, by an approximate determination of its vapor density, and by the lowering of the freezing point of its aqueous solution (B. 19, 1842; 21, 1570). Nitrous acid first converts hexamethylenetetramine into dinitrosopentamethylenetetramine, and this then into trinitrosotrimethylenetriamine. When it is considered that trimethylene- trimethyltriamine is formed by the interaction of methylamine and formaldehyde, it is obvious that the reaction must cease at this point, because the imide-hydrogen atoms have been replaced by methyl groups. Ammonia and formaldehyde yield at first trimethylenetriamine, corresponding to trimethylenetrimethyltriamine, which absorbs ammonia and formaldehyde, splits off water and becomes pentamethylene- diamine. The latter is converted by formaldehyde into hexamethylenetetramine The following constitutional formulas aim to represent this deportment (compare Roscoe-Schorlemmer (1884), vol. in, 646; Duden and Scharff, A. 288, 218) : Trimethylenetriamine Pentamethylenetetramiire Hexamethylenetetramine. The following bodies are produced when primary amines act upon formaldehyde (B. 28, R. 233, 381, 924; 29, 2110) : Methylmethyleneamine, [CH 2 = N . CH 3 ] 3 , boiling point, 166 ; sp. gr., 0.9215 (187). Ethylmethyleneamine, [CH 2 N -C 2 H 5 ] 3 , boiling point, 207 ; sp. gr. , 0.8923 (18.7). w-Propylmethyleneamine, [CII 2 = N. C 3 H 7 ] 3 , boiling point, 248; sp. gr., 0.880 (18.7). By the use of aldehydes with higher molecular weight, the tendency to poly- merization on the part of the reaction products of primary amines and aldehydes diminishes : Methylisobutyleneamine, (CH 3 ) 2 CH . CH = N . CH 3 , boils at 68. Secondary amines and formaldehyde yield Tetramethylmethylenediamine, CH. CH 3 . CII(OH)NII, ? 4H --^ CH 3 CHO -f SO 4 H . NH 4 . 2O6 ORGANIC CHEMISTRY. In contact with water it passes into amorphous Hydracetamide, C 6 H, 2 N 2 . Sodium nitrite, added to a slightly acidulated solution of aldehyde-ammonia, produces Nitrosoparaldimine, C 6 H 12 O 2 (N . NO), which by reduction becomes amido paraldimine, C 6 H 12 O 2 (N . NH 2 ), and this in turn, by the action of dilute sulphuric acid, splits off Hydrazine, NH 2 . NH 2 (B. 23, 740). Paraldimine should be viewed as paraldehyde in which an oxygen atom has been replaced by the imido group. Hydrogen sulphide changes aldehyde-ammonia to Thialdin (p. 203), while with prussic acid it becomes the nitrile of a-amidopropionic acid (see this). A rather re- markable reaction occurs when aldehyde-ammonia acts upon aceto-acetic ester. It is the formation of I, 3, 5- Trimethyldihydropyridine-dicarbonic ester (see this). Chloral-ammonia, CCl 3 CH<;;Jj 2 , melts at 63. For the chloralimides, (CC1 3 . CH : NH) 3 , and Dehydrochloralimides, C 6 H 4 C1 9 N S , consult B. 25, R. 794; 24, R. 628. The isomerism of the former is very probably dependent upon the same causes as that of the polymeric thioaldehydes (p. 203). C. Aldoximes, R'. CH = N . OH (V. Meyer, 1863). The aldoximes are formed when hydroxylamine, an aqueous solu- tion of the hydrochloride (i mol.), mixed with an equivalent quantity of soda (^ mol.) acts in the cold upon aldehydes. At first there is very evidently formed an unstable addition product, corresponding to aldehyde-ammonia, which in the case of chloral may be obtained in stable form, but which passes readily into the oxime : \H CCI c NOH . The aldoximes are colorless liquids which boil without decomposition. The first members of the series dissolve readily in water. When boiled with acids they are again changed to aldehyde and hydroxylamine. By the action of acetic anhydride or acetyl chloride the aldoximes become nitriles : CH 3 CH = NOH -f (CH 3 CO) 2 O = CH 3 CN -f 2CH 3 CO 2 H. Acetoxime Acetonitrile. The oximes and hydrazones (p. 207), like the aldehydes, take up prussic acid ; the products are amidoxyl- or hydrazino-nitriles (B. 29, 62) Formoxime, Formaldoxime^ CH 2 = N . OH, boils at 84, and passes spontane- ously into polymeric triformoxime, CH 2 <^|^j ' CH 2 > N ' OH ( R 29 ' R " 6 ^' Formoxime yields hydrocyanic acid when it is boiled with water (B. 28, R. 233). Acetaldoxime, CH 3 . CH : NOH, melting at 47 and boiling at 115, also exists in a second modification, melting at 12, which readily reverts to the first form (B. 26, R. 610; 27, 416). Chloralhydroxylamine, CC1 3 . CH(OH)NH(OH), melts at 89 (B. 25, 702), and even upon standing in the air becomes Chloraloxime, CC1 3 CH = NOH, melting at 39-40. Propionaldoxime, C 2 H 5 . CH = N . OH, boils at 130-132. Isobutyraldoxime, (CH 3 ) 2 CH . CH = NOH, boils at 139. Isovaleraldoxime, (CH 3 ) 2 CH . CH 2 . CH = NOH, boils at 164-165. CEnanthaldoxime, CH 3 (CH 2 ) 5 - CH : NOH, melts at 55.5 and boils at 195. Myristinaldoxime melts at 82 (B. 26,2858). The aldoximes of the fat series resemble the aromatic synaldoximes in their deportment (B. 28, 2019). OLEFINE ALDEHYDES. 207 D. Diazoparaffins are produced, as shown by v. Pechmann in 1894, by the action of alkalies upon nitrosamines. Diazomethane alone has been carefully studied. Diazomethane, Azimet/iylene, CH 2 N 2 , is at the ordinary temperature a yellow, odorless, but very poisonous gas, which strongly attacks the skin, the eyes, and the lungs. It is best made by the action of alkalies upon nitrosomethylurethane : NO N CH,N X -f NaOH = CH.,( || -f H 2 O -f NaO . CO 2 C 2 H 5 . X C0 2 C 2 H 5 X N Diazomethane exhibits the reactivity of diazoacetic ester (see this). Water con- verts it into methyl alcohol. Iodine changes it to methylene iodide. Inorganic and organic acids are changed into their methyl esters : hydrochloric acid into methyl chloride; prussic acid into acetonitrile ; phenols into anisols ; toluidine into methyl toluidine. Diazomethane and fumaric methyl ester unite to pyrazolindicarboxylic ester (B. 28, 1624, 2377). E. Aldehyde Hydrazones (E. Fischer, A. 190, 134; 236, 137). The aldehyde hydrazones correspond to the aldoximes. They are the transposition* products of aldehydes and hydrazines (see these), which are formed when their constituents are mixed in ethereal solution. The water produced in the reaction is removed by K 2 CO 3 , and the hydrazones then purified by distillation under diminished pressure : CH 3 CHO -f H 2 N . NHC 6 H 5 = CH 3 CH = N . NHC 6 H 5 -f H 2 O. Acetaldehyde Hydrazone, Ethidene Phenylhydrazine, CH 3 . CH = NNH- C 6 H 5 , boils at 140 (20 mm.). Crystals, melting at 63-65, separate from the cold solution of the freshly distilled preparation, dissolved in 75 per cent, alcohol. If the liquid, after the addition of 4 c.c. of cone, sodium hydroxide, be heated to boiling for three minutes, a second modification, melting at 98-101, will separate out upon cooling. When azophenylethyl (see this) is dissolved in cold, concentrated sulphuric acid, it changes to acetaldehydephenylhydrazone (B. 29, 793). Aldehyde precipi- tates the body CH 3 .CHO. 2(C 6 H 5 NHNH 2 ), melting at 77.5, from the solution of phenylhydrazine bitartrate (B. 29, R. 59'6). Propylaldehydephenylhydratone^ CH 3 . CH 2 .CH = N 2 C 6 H 5 , boils at 205 (180 mm.). These hydrazones take up prussic acid and pass into the nitriles of hydrazido-acids (B. 25, 2020). Formaldehyde differs from the higher homologues in that with phenylhydrazine it yields Trimethylene Phenylhydrazine, (C 6 H 5 N 2 ) 2 (CH 2 ) 3 , melting at 183-184 (B. 29, 1473 ;R. 777). Formalazine, CHj = N N = CH 2 (?), from formaldehyde and hydrazine, is a white, amorphous, somewhat hygroscopic mass (B. 26, 2360). aB. OLEFINE ALDEHYDES, C a U ZTri . CHO. The unsaturated aldehydes, having a double carbon union, bear the same relation to the olefine alcohols (p. 130) that the paraffin alde- hydes sustain to their corresponding alcohols. Their aldehyde group shows the same reactive power as the group in the ordinary aldehydes. In addition, the unsaturated residue, C n H 2n !, gives rise to addition- reactions similar to those shown by the olefines. Some of the olefine aldehydes are connected with the saturated aldehydes by condensation reactions; e.g., crotonaldehyde, tiglic aldehyde, methyl acrolein, etc. 208 ORGANIC CHEMISTRY. Acrolein, C 3 H 4 O = CH 2 : CH . CHO, boils at 52. It is produced by the oxidation of allyl alcohol and by the distillation of glycerol or fats (i pt.) with potassium bisulphate (2 pts.) (B. 20, 3388; A. Sup. 3, 1 80): CH 2 OH CHOIl CHO CHO CHOH -~ H2 -->CH CH 2 OH CH 2 OH CH 2 OH Acrolein is a colorless, mobile liquid, possessing a sp. gr. of 0.8410 at 20. It has a pungent odor and attacks the mucous membranes in a frightful manner. It is soluble in 2-3 parts water. It reduces an ammoniacal silver solution, with formation of a mirror-like deposit, and when exposed to the air it oxidizes to acrylic acid. It does not combine with primary alkaline sulphites. Nascent hydrogen converts it into ally I alcohol ($. 130). Phosphorus pentachloride converts acrolein into propylene dichloride, CH 2 : CH .- CHC1 2 , boiling at 84 C. With hydrochloric acid it yields /3-chlorpropionic alde- hyde (p. 199). With bromine it yields a dibromide, CH 2 . Br. CHBr . CHO, which becomes ,/3-dibrompropionic acid upon oxidation with nitric acid. Baryta water converts it into a-acrose or (d -)- l)-ftuctose_(see this). When preserved, acrolein passes into an amorphous, white mass (disacryl). On warming the HC1 compound of acrolein (see above) with alkalies or potassium car- bonate metacroleln is obtained. The vapor density of this agrees with the formula (C 3 H 4 O) 3 . It fuses at 45-46. Ammonia changes acrolein to the so-called acrolein- ammonia, 2C 3 H 4 O -|- NH 3 = C 6 H 9 NO -|- H 2 O. This is a yellowish mass that on drying becomes brown, and forms amorphous salts with acids. It yields picoline, C 6 H 7 N (methylpyridine, C 5 H 4 - N.CH 3 ), when distilled. Hydrazine changes acrolein to pyrazoline, and phenyl- hydrazine converts it into l-phenylpyrazoline (B. 28, R. 69). Crotonaldehyde, C 4 H 6 O = CH 3 . CH : CH . CHO, boils at 104 (Kekule, A. 162, 91). It is obtained by the condensation of acetal- dehyde (p. 195) from the primarily formed tf/<7^/when heated with dilute hydrochloric acid, with water and zinc chloride, or with a sodium acetate solution, to 100 C. (B. 14, 514 ; 25, R. 732). When aldol is heated or treated with dilute hydrochloric acid it splits off water and becomes crotonaldehyde : 2CH 3 .CHO - -- CH 3 .CH(OH).CH 2 .CHO - --->- CH 3 .CH =CH.CHO. Crotonaldehyde is a liquid with irritating odor; at o it has a sp. gr. of 1.033 and boils at 104. On exposure to the air it oxidizes to crotonic acid ; it reduces silver oxide (B. 29, R. 290). It combines with hydrochloric acid to form fi-chlorbutyr- aldehyde (p. 199) ; on standing with hydrochloric acid it unites with water and becomes aldol. Iron and acetic acid change it to croton-alcohol, butyraldehyde and butyl atcohoL When the alcoholic solution of acetaldehyde-ammonia is heated to 120, Cro- tonal-ammonia, C 8 H 13 NO (Oxtetraldine), is produced. It is a brown, amorphous mass. When heated it breaks up into water and collidine, C 8 H n N (see this). Tiglic Aldehyde, guaiacol, CH 3 CH = C(CH 3 ) . CHO, boils at 116. It may OLEFINE ALDEHYDES. 2OQ be obtained by the distillation of guaiacol resin and by the condensation of ethyl- and propyl-aldchydes. Methyl-ethyl Acrole'in, C 2 H 5 . CH : C(CH 3 ). CHO, is produced by the con- densation of propionic aldehyde (p. 196), and boils at 137 C. Citronellal and its isomeride Rhodinal are olefine aldehydes, and Geranial or Citral belongs to the class of diolefine aldehydes. These will be duly considered under the olefine terpenes. 2C. Acetylene Aldehydes, C n H 2n _ 3 . CHO. Propargylic Aldehyde, CH | - C.CHO, boils at 59. It is produced when the acetal, CH j C . CH (OC 2 H 5 ) 2 , boiling at 140, from dibrom-acrolein acetal and alcoholic potash, is boiled with dilute sulphuric acid. It is a very mobile liquid, which provokes tears. Its silver salt is very explosive Sodium hydrate at the ordinary temperature decomposes propargylic aldehyde instantly into acetylene and sodium formate : CH j C . CHO + NaOH =: CH : CH + NaO . CHO (L. Claisen, privately communicated). 3 A. Ketones of the Limit Series, Paraffin Ketones, In the introduction to the aldehydes and ketones (p. 187) atten- tion was directed to the great similarity between these two classes of compounds, which finds expression in their most important methods of formation and in their transposition reactions. It was also there stated that two different kinds of ketones were known : 1. Simple ketones, containing two similar alkyls. 2. Mixed ketones, having two different alkyls. Methods of Formation. i. Oxidation of secondary alcohols, whereby the = CH . OH-group is transposed to the = CO-group (p. 187). 2. A variety of ketones, the pinacolines, is obtained from the ditertiary glycols the pinacones (see these) by the withdrawal of water. This is effected by means of hot hydrochloric acid or hot dilute sulphuric acid. The simplest ditertiary glycol is tetramethyl glycol, or pinacone. It might be expected that when this lost water, tetramethyl-ethylene oxide would be produced. However, by the occurrence of a remarkable intramolecular atomic rearrangement it yields the simplest pinacoline, tertiary butyl-methyl ketone : (CH 3 ) 2 C(OH) (CH 3 ) 2 C\ 1 V - I O - ->(CH 3 ) 3 C.CO.CH 3 2 C(OH) (CH 3 ) 2 C/ Tetramethyl Glycol Tertiary Butyl-methyl Ketone, Pinacbne Pinacoline. 3. By heating the ketone chlorides with water: (CH 3 )CC1 2 -"*- (CH 3 ) 2 CO. 4. By action of acids (B. 29, 202) upon the sodium salts of the mononitro- paramns (pp. 156, 157), .in which the nitro-group is attached to a terminal carbon atom : 2(CH s ) a C<*J* + 2 HC1 = 2(CH 3 ) 2 CO -f N 2 + 2NaCl -f H 2 O. Nucleus-synthetic Methods of Formation. 5. By the distillation of calcium or barium acetates and their higher homologties. Such a salt, when heated alone, yields a simple ketone. The distillation of a mixture 18 210 ORGANIC CHEMISTRY. of equimolecular quantities of the salts of two acids results in the formation of mixed ketones (p. 188). In making ketones with high molecular weight it is best to carry out the distillation under diminished pressure. Some normal fatty acids have yielded ketones on treatment with P 2 O 5 (B. 26, R. 495). 6. The action of the zinc alkyls upon the chlorides of the acid radicals (Freund, 1860). The reaction is similar to that occurring in the formation of the tertiary alcohols (p. 114). At first the same intermediate product is produced (A. 175, 361; 188, 104): rCH 3 CH 3 . COC1 + Zn(CH 3 ) 2 = CH 3 . C j O . Zn . CH 3 , which (with a second molecule of the acid chloride) afterwards yields the ketone and zinc chloride : rCH. CIL . C \ O . Zn . CH 3 + CH 3 . COC1 = 2 CH 3 . CO . CH 3 + ZnCl 2 . lei In many cases, especially in the preparation of pinacolines from trimethyl-acetyl chloride and zinc methide, it is more advantageous to immediately decompose the addition product of zinc methide and acid chloride with water, when the zinc hydroxide will be transposed by the hydrochloric acid into zinc chloride : /O ZnCH 3 CH 3 C CH 3 + 2H 2 = CH 3 . CO . CH 3 + Zn(OH) 2 + HC1 -f- CH 4 . \C1 7. By the action of anhydrous ferric chloride upon the acid radicals. Hydro- chloric acid is evolved, and chlorides of /3-ketone carboxylic acids are produced. From these water liberates the free /3-ketone carboxylic acids. The latter break down readily into carbonic acid and ketones (compare method of formation 8) : CH 3 CH 3 Fe 2 Cl 6 H 2 -C0 2 2C 2 H 5 COC1 H3 2 H 5 . CO. CH. COC1 ^C 2 H.CO. CH. CO 2 H ^C 2 H 5 . CO. C 2 H 5 8. By the oxidation of dialkyl acetic acids, and the a-oxydialkyl-acetic acids corresponding to them ; the latter are simultaneously formed as intermediate products in the oxidation of the former compounds, e.g. : (CH 3 ) 2 CH . C0 2 H -% (CH 3 ) 2 C(OH) . C0 2 H --> (CH 3 ) 2 CO + CO 2 + H 2 O. 9. By the breaking down of /3-ketone mono- and dicarboxylic acids e. g.: CH 3 . CO . CH 2 . CO 2 H < Acetoacetic Acid CH 3 COCH 3 . C0 2 HCH 2 COCH 2 C0 2 H - - <:. Acetone Dicarboxylic Acid. "'* _ Compare acetoacetic ester, and also acetone dicarboxylic acid. OLEFINE ALDEHYDES. 211 The ketones are produced in the dry distillation of citric acid, sugar, cellulose (wood), and many other carbon compounds. Nomenclature and Isomerism. The term ketone is derived from the simplest and first discovered ketone acetone. The names of the ketones are obtained by combining the names of the alky Is with the syllable ketone e. g., dimethyl ketone, methyl-ethyl ketone, etc. A. Baeyer regards the ketones as keto-substitution products of the hydrocarbons, and the group CO, uniting two alkyl groups, he terms the keto-group. As one carbon atom in the name ketopropane would, in consequence of this suggestion, be twice designated, Kekule has suggested that the oxygen linked doubly to carbon be called "oxo "-oxygen. Then acetone, CH 3 COCH 3 , would be 2-oxopropane, pro- pionic aldehyde, CH 3 . CH 2 . CHO, would be \-oxopropane. The " Geneva names " are obtained by adding the suffix "on" to the name of the hydrocarbon: acetone is called [Propanon], and methyl-ethyl ketone is [Butanon]. As there 'is a ketone for every secondary alcohol, the number of isomeric ketones of definite carbon content is equal to the number of possible secondary alcohols containing the same number of carbon atoms. The simple ketones are isomeric with the mixed ketones having a like carbon content. The isomerism of the ketones among them- selves is dependent upon the homology of the alcohol radicals united with the CO-group. Consult the isomerism of the aldehydes (p. 190) for the isomerism of the ketones with other compounds. Properties and Transformations. The ketones are neutral bodies. The lower members of the series are volatile, ethereal-smelling liquids, while the higher members are solids. In enumerating the transpositions possible with ketones, it will be best to present acetone, the most important and most thoroughly in- vestigated member of this class of bodies. i. Ketones differ chiefly from aldehydes in their behavior when oxidized. They are not capable of reducing an alkaline silver solution. They are not so easily oxidized as the aldehydes. When more powerful oxidants are employed, the ketones almost invariably break down at the union with the CO-group. Carboxylic acids are produced, and in some cases ketones with a lower carbon content : CH 3 . CO . CH 3 - > CH 3 . C0 2 H and H . CO 2 H - -4- CO 2 -f H 2 O. C 2 H 5 . CO . C 2 H. ~ -> C 2 H 5 . CO 2 H and CH 3 . CO 2 1I. In the case of mixed ketones, when both alcohol radicals are primary in character, the CO-group does not, as was formerly supposed, remain exclusively with the lower alcohol radical, but the reaction proceeds in both possible directions, e. g.: I 3 . CO 2 H and CO 2 H . CH 2 . CH 2 . CH 3 1 3 . CH 2 . CO 2 H When a secondary alcohol radical is present it splits off as ketone, and is then 212 ORGANIC CHEMISTRY. further oxidized, whereas in the case of a tertiary alcohol radical the CO-group remains combined as carboxyl. The direction in which the oxidation proceeds is dependent less upon the oxidizing agent than upon the oxidation temperature (A. 161, 285 ; 186, 257; B. 15, 1194; 17, R. 315; 18, 2266, R. 178; 25, R. 121). It is remarkable that pinacoline (p. 209) was successfully oxidized by potassium permanganate to the corresponding a-ketone carboxylic acid of like carbon content : trimethyl pyroracemic acid : (CH S ),C . CQ . CH 3 3 -> (CH 3 ) 3 C . CO . CO 2 H. Pinacoline Trimethyl-pyroracemic Acid. 2. Concentrated nitric acid breaks the ketones down, and converts them in part into dinitro-paraffins (p. 159) : (C 2 H.) 2 CO --> CH 3 CH(N0 2 ) 2 (CH 3 . CH 2 . CH 2 ) 2 CO - *- CH 3 . CH 2 CH(NO 2 ) 2 . 3. Amyl nitrite, in the presence of sodium ethylate or hydrochloric acid, converts the ketones into isonitroso- ketones : CH 3 . CO . CH 3 NQQC5Hn > CH 3 . CO . CH(NOH) CH 3 CO . CH 2 . CH 3 - CH 8 .CO.C(NOH).CH 3 . The isonitroso-ketones will be discussed later as the monoximes of a-kelo-alde- hydes or a-diketones. Many of the addition reactions possible with ketones are due, as in the case of the aldehydes, to the ready destruction of the double union between carbon and oxygen. These reactions are partly followed, even with the ketones, by an immediate exit of water. 4. Nascent hydrogen (sodium amalgam) converts the ketones into secondary alcohols (p. 113), from which they are produced by oxida- tion. Pinacones, or di tertiary glycols, are simultaneously formed (p. 209) : (CH 3 ) 2 CO -f 2H = (CH 3 ) 2 CH . OH. 5. The ordinary ketones, like the ordinary aldehydes, are little disposed to com- bine with water. Acetones, containing numerous halogen atoms, unite with 4H 2 O and 2H 2 O, forming hydrates. The ketone derivatives, corresponding to the acetah (p. 200), are produced when the /3-dialkyloxycarboxylic acids split off CO 2 , and by the interaction of ketones and orthoformic ether (Claisen). 6. The ketones resemble the aldehydes in their deportment a. With hydrogen sulphide ; b. With mercaptans in the presence of hydrochloric acid. The products are po lymeric thioketones (p. 218), and the mercaptols, e. g., (CH 3 ) 2 - C(SC 2 H 5 ) 2 , corresponding to the mercaptals (p. 204). 7. The ketones, unlike the aldehydes, do not combine with the acid anhydrides. Pinacoline alone unites with acetic anhydride to form a diacetate, melting at 65 (B. 26, R. 14). 8. Only those ketones, which contain a methyl group, form crys- OLEFINE ALDEHYDES. 213 talline compounds with the alkaline bisulphites. These can be con- sidered as salts of oxysulphonic acids : (CH,),CO + S0 3 HNa - (CH 3 ) 2 C<* Na . These double salts serve well for the isolation and purification of the ketones, which can be liberated from them by dilute sulphuric acid or a soda solution. 9. Behavior of ketones with ammonia, hydroxylaminc and phenyl- hydrazine. (a) Acetone behaves differently toward ammonia from the aldehydes. Nucleus-synthetic reactions occur, with the formation of diacetonamine and triacetonamine (p. 219). With hydroxylamine, however, the ketones yield (ti) ketoximes (p. 219) and (c) with phenyl- hydrazine they form hydrazones (p. 220). In these respects they re- semble the aldehydes (p. 207). 10. When phosphorus trichloride acts upon acetone hydrochloric PC1_0 acid is evolved, and there results the compound CH 3 . CO . CH_C (CH 3 ) 2 (B. 17, 1273; 18,898). 11. Phosphorus pentachloride, phosphorus trichlor-dibromide, and phosphorus tribromide replace the oxygen of the ketones by two chlo- rine or two bromine atoms. This reaction answers for the preparation of dichlor- or dibrom-paraffins in which an intermediate C-atom carries the two halogen atoms. As these ketone chlorides readily exchange their chlorine for hydrogen, they constitute a means of converting the ketones into the corresponding paraffins. 12. The hydrogen atoms of the alkyl groups present in the ketones can be re- placed by chlorine and bromine. 13. The lower members of the series of aldehydes showed a great tendency to polymerize, but no ketone has been known to do this. Ketones, in contrast to aldehydes, are symmetrically constructed. 14. By the action of amyl nitrite and sodium ethylate or hydrochloric acid upon the ketones, isonitrosoketones result ; these contain the CH or CH 2 groups, together with the CO-group. Nucleus-synthetic Reactions of the Ketones. Reactions of this class were observed in the action of ammonia and of phosphorus trichloride, in the presence of aluminium chloride, upon acetone (compare 9 and 10). The latter is capable of such deport- ment. The following are, however, more important : (i) Just as two aldehyde molecules condense to aldol, so aldehyde or chloral will unite with acetone, forming hydracetyl acetone and trichlorhydracetyl acetone (see this) : CH 3 . Acetone will also condense with other aldehydes, e.g. , benzaldehyde. But it is impossible to fix the ketone-alcohols which form at first. There is an exit of water, and unsaturated derivatives are produced, just as in the condensation of two mole- cules 'of aldehyde to crotonaldehyde. Thus, two molecules of acetone, in the presence of ZnCl 2 , HC1, SO 4 H 2 , unite directly with the exit of water and the formation of 214 ORGANIC CHEMISTRY. mesityl oxide (p. 219), which in turn condenses with a third molecule of acetone to phorone (p. 219). The ketone alcohols, first formed, were not tangible: (CH 3 ) 2 CO + CH 3 .CO.CH 3 = CH 3 > C = CH.CO.CH 3 + H 2 O Mesityl Oxide 3 > c = CH. CO. CH 3 + CO(CH 3 ) 2 = c^ 3 >C = CH. CO. CH = C<^ + H 2 O. Phorone. (2) Acetone and other ketones, having a suitable constitution, pass over, under the influence of concentrated sulphuric acid, into sym- metrical trialkyl benzenes. It is very probable that there is an inter- mediate formation of alkylized acetylenes (p. 98). Acetone yields mesitylene : CH 3 CH 3 /CH 3 SO 4 H / ' \ /CH=Cx 3 CO L > (.) -> CH - C H - CH 3 CH - \CH, Acetone Allylene Mesitylene. (3) Acetone condenses with lime or sodium ethylate to isophorone, a trimethyl oxo-cyclo-hexene (see this). (4) The ketones, like the aldehydes, unite with hydrogen cyanide to form oxycy- anides or cyanhydrins, the nitriles of the a-oxyacids. They will be described after the a-oxyacids, into which they pass when treated with hydrochloric acid : (CH 3 ) 2 CO > (CH 3 ) 2 C< 2 o -> (CH,),. C<. a-Oxyisobutyric Acid. (5) Acetone in the presence of caustic soda combines with chloroform, yielding acetone chloroform. It is a derivative of a-oxyisobutyric acid. The latter can be obtained from it : (CH 3 ) 2 CO s *- (CH 3 ) 2 C<^ - -> (CH,) a Caurone Myristone, . Stearone 2l6 ORGANIC CHEMISTRY. Diethyl kelone is produced from carbon monoxide and potassium ethide (p. 184). Tetramethyl- and tetraethyl-acetone have been obtained as decomposition products of penta-methyl &t\& penta- ethyl phloroglucin, when these bodies were oxidized by air (B. 25, R. 504). (b] Mixed Ketones. Most of the members of this class are made by the distilla- tion of the barium salts of the corresponding acids with barium acetate (p. 209). Name. Methyl Ethyl Ketone [Butanon], . . Methyl Propyl Ketone [2-Pentanon], Methyl Isopropyl Ketone [Methyl Butanon], Pinacoline, Methyl Tertiary Butyl Ketone, Methyl Oenanthone, Methyl Hexyl Ketone, Methyl Nonyl Ketone, Methyl Decyl Ketone, Methyl Undecyl Ketone from Laurie Acid, Methyl Dodecyl Ketone, Methyl Tridecyl Ketone from Myristic Acid, Methyl Tetradecyl Ketone, .... Methyl Pentadecyl Ketone from Pal- mitic Acid, Methyl Hexadecyl Ketone from Mar- garic Acid, Methyl Heptadecyl Ketone from Stearic Acid, Formula. CH a CH 3 CH 3 . CH 3 . CH 3 CH 3 CH, . CO . C 3 H, .CO.CH(CH 3 ) 2 CO.C(CH 3 ) 3 .CO.C n H 23 CH 3 CH 3 . co . . CO . C 13 H 27 .CO.C U H 29 CH 3 CH 3 CH 3 CH, CH 3 .CO.C 17 H 35 . M. P. B. P. 28 34 39 43 48 52 55 81 102 1 06 I 7 I 225 247 263 (207) (22 4 ) (23I ) (244) (252) (265) The boiling points, inclosed in parentheses, were determined under loo mm. pressure. Pinacoline is obtained by the withdrawal of water from pinacone, called hexylene gly col, from tetramethyl glycol (CH 3 ) 2 C(OH) . C(OH)(CH 3 ) 2 , and from trimethyl acetyl chloride and zinc methide (p. 209). When oxidized with chromic acid, it breaks down into trimethyl acetic acid and formic acid. Potassium permanganate converts it into trimethyl pyroracemic acid (see this). Pinacolyl alcohol fp. 129) is the product of its reduction. Homologous pinacones yield homologous pinacolines ; thus, methyl ethyl pinacone, ( ?^ 3 >C(OH) . C(OH)<^^| , yields ethyl tertiary (CH,) f , amyl ketone, ^C . CO . C 2 H 5 , boiling at 150. 2 tic Methyl-nonyl Ketone is the chief constituent of oil of rue (from Ruta grave- olens] ; it may be extracted from this by shaking with primary sodium sulphite. I. HALOGEN SUBSTITUTION PRODUCTS OF THE KETONES, PARTICU- LARLY ACETONE. Monochloracetone, CH 3 . CO . CH 2 C1, boiling at 119, is obtained by conduct- ing chlorine into cold acetone (A. 279, 313), in the presence of marble (B. 26, 597). Its vapors provoke tears. There are two possible Dichloracetones, C 3 H 4 C1 2 O : (a] CH 3 . CO. CHC1 2 and (/3) CH 2 C1 . CO . CH 2 C1. The first is formed on treating warmed acetone with KETONE HALOIDS. 21 7 chlorine, and is obtained from dichloraceto-acetic ester (B. 15, 1165). It boils at 120. The /3-dichloracetone is obtained by the chlorination of acetone and in the oxidation of a-dichlorhydrin, CH 2 C1 . CH(OII) . CH 2 C1 (see glycerol), with potas- sium dichromate and sulphuric acid. It melts at 45, and boils at I72-174. Symmetrical Tetrachloracetone, CHC1 2 . CO. CHC1 2 -f 2H 2 O, is readily ob- tained by the action of potassium chlorate and hydrochloric acid upon chloranilic acid (B. 21, 318) and triamidophenol (B. 22, R. 666), or of chlorine upon phloro- glucin (B. 22, 1478). It melts at 48. Unsymmetrical Tetrachloracetone, CH 2 C1 . CO . CC1 3 , boiling at 183, is produced by the action of chlorine upon isopropyl alcohol (B. 28, R. 61). Pentachloracetone, CHC1 2 . CO . CC1 3 , boiling at 193, is obtained from chlorine and acetone (A. 279, 317)- Monobromacetone, CH 2 Br . CO. CH 3 , boils at 31 (8 mm.) (B. 29, 1555). Perbromacetone, CBr s . CO . CBr 3 , melting at I io-i 1 1, is obtained from triamido- phenol (B. 10, 1147), and bromanilic acid (B. 20, 2040; 21, 2441) by means of bromine and water. lodoacetone, CH 3 .CO.CH 2 I, boiling at 58 (ll mm.) is produced when potassium iodide in methyl alcohol solution acts upon mono-chloracetone (B. 29, 1557). It is a heavy oil with a disagreeable odor (B. 18, R. 330). /3-Di-iodoacetone, CH 2 I . CO. CH 2 I, forms when iodine chloride acts upon acetone. fi-Chlorisobutyl-methyl Ketone, (CH 3 ) 2 . CC1 . CH 2 . CO . CH 3 , and Di-$-chloriso- butyl Ketone, (CH 3 V 2 CC1 . CH 2 . CO . CH 2 CC1(CH 3 ) 2 , are the readily decomposable addition products of mesityl oxide and phorone with hydrochloric acid. u-Brombutyl- methyl Ketone ', see Acetobutyl alcohol. y-Dibrom-kettnus are prepared from the oxetones (see these) by the addition of 2HBr. e.g. : y-Dibrombutvl Ketone, (CH 3 CHBr . CH 2 . CH 2 ) 2 CO, is formed from dimethyl oxetone and 2HBr, or by the addition of 2HBr to diallyl acetone (p. 221). a-Dichlor~ketones are discussed with the diketones. a. ALKYL ETHERS OF THE ORTHO-KETONES. The ketones maybe regarded as the anhydrides of hypothetical glycols, which bear the same relation to the ketones that the orthocarbonic acids sustain to the carbonic acids. In this sense it is then permissible to speak of ortho-ketones. Their alkyl ethers, corresponding to the acetals. are produced by heating the /?-diethoxy-carbonic acids, and also from acetone by means of orthoformic ester (Claisen, B. 29, 10x37) : CH 3 . C(O . C 2 H 5 ) CH 2 . CO 2 H >. CH 3 . C(O . C 2 H 5 ) 2 . CH 3 + CO 2 CH 3 .-CO . CH 3 -f HC(0 . C 2 H 5 ) 3 -> CH 3 . C(O . C 2 H 5 ) 2 CH 3 + HCO 2 C 2 H 5 . Ortho-acetone Methyl Ether, (CH 3 ) 2 C(O . CH 3 ) 2 , boils at 83. Ortho-acetone Ethyl Ether, boiling at 114, is a liquid with an odor resembling that of camphor. These substances are stable when alone. Water or a trace of mineral acid causes them to break down into ketones and alcohols. 3. KETONE HALOIDS Are produced, as mentioned on page 213, by the action of PC1 5 , PCl 3 Br 2 , and PBr 5 upon ketones. Acetone chloride, Chloracctol, CH 3 . CC1 2 . CH 3 , boils at 70 ; sp. gr. 1.827 at 16. Bromacetol boils at 114; sp. gr. 1.8149 ()- Methyl-ethyl dichlor- methane, CH 3 . CC1 2 . C 2 H 5 , boils at 96. Methyl-ethyl dibrommethane boils at 144. Methyl tertiary butyl dichlormethane, CH 3 . CC1 2 . C(CH 3 ) 3 , boils at 151. 19 2l8 ORGANIC CHEMISTRY. 4. SULPHUR DERIVATIVES OF THE PARAFFIN KETONES. A. Thioketones and their Sulphones. When hydrogen sulphide acts upon a cold mixture of acetone and concentrated hydrochloric acid, the first product is a volatile body with an exceedingly disagreeable odor, which disseminates itself aston- ishingly rapidly. It is probably simple thio-acetone, which has not been further investigated. The final product of the reaction is /S /C(CH 3 ) 2 Trithioacetone, (CH 3 ) 2 C S ' , melting at 24, and boiling at 130 \S__^C(CH 3 ) 2 (13 mm.). Potassium permanganate oxidizes it to Trisulphone Acetone, [(CH 3 ) 2 CSO 2 ] 3 , melting at 302. When distilled at the ordinary pressure it is converted into Dithioacetone, (CH 3 ) 2 CC(CH 3 ) 2 , boiling at 183-185. This is also formed in the action of phosphorus trisulphide upon acetone. It is converted, by oxidation, into Disulphone Acetone, [(CH 3 ) 2 CSO 2 ] 2 , melting at 220-225. B. Mercaptols and their Sulphones. Although the ketone derivatives corre- sponding to the acetals can not be derived from ketones and alcohols by the with- drawal of water, it is possible to obtain the mercaptols faz ketone derivatives corre- sponding to the mercaptals in this manner, but best, however, by the action of hydrochloric acid upon ketones and mercaptans : TT(~M (CH 3 ) 2 CO + 2C 2 H 5 SH -> (CH 3 ) 2 qSC 2 H 5 ) 2 + H 2 O. Like the mercaptals, they are liquids with unpleasant odor. Acetone Ethyl Mercaptol, Dithioethyl dimethyl methane, (CH 3 ) 2 C(SC 2 H 5 ) 2 , boiling at 190-191, may be prepared from mercaptan. However, to avoid the very intolerable odor of the latter, sodium ethyl thiosulphate and hydrochloric acid are used (p. 153). It combines with methyl iodide (B. 19, 1787; 22, 2592). By this means, from a series of simple and mixed ketones, corresponding mercaptols have been made, and in nearly all instances they have been oxidized to the corresponding sulphones, some of which possess medicinal value. Sulphonal, Acetone Diethyl Sulphone, (CH 3 ) 2 C(SO 2 C 2 H 5 ) 2 , melting at 126, was discovered by Baumann, and introduced into medicine, as a very active sleep- producing agent, by Kast in 1 888. Acetone mercaptol is oxidized to it by potas- sium permanganate : (CH 3 ) 2 ; C(SC 2 H 5 ) 2 &- -> (CH 3 ) 2 C(S0 2 C 2 H 5 ) 2 . Sodium hydroxide and methyl iodide (A. 253, 147) acting upon ethidene diethyl sulphone (p. 204) produce it : CH 3 CH(S0 2 C 2 H 5 ) 2 Trional, Methyl-ethyl ketone-diethyl sulphone, diethyl-sulphone-methyl- ethyl- /"ITT methane, c H 3 >C(SO 2 C 2 H 5 ) 2 , melting at 75 ; Tetronal, Propione-diethyl sit/- phone, (C 2 H 5 ) 2 C(SO 2 C 2 H 5 ) 2 , melting at 85; Propione-dimethyl Sulphone, (C 2 H 5 ) 2 C(SO 2 CH 3 ) 2 , melting at I32-I33, and other "sulphonah" are prepared similarly to sulpJional, and act in like manner. However, Acetone-dimethyl Sulphone, (CH 3 ) 2 C(SO 2 CH 3 ) 2 , not containing an ethyl group, no longer acts like sulphonal. C. Oxysulphonic Acids of the Ketones. The alkali salts of these acids are the addition compounds produced by the union of the ketones with the alkaline bisulphites, e. g., sodium acetone -oxysulph^n ate, (CH 3 ) 2 C<'QT| i & (p. 2I 3)- NITROGEN DERIVATIVES OF THE KETONES. 2 19 5. NITROGEN DERIVATIVES OF THE KETONES. A. Nitro-compounds. Pseudonitrols (p. 157) and Mesodinitroparaffins (p. 158) have already been discussed after the mononitroparaffins. B. Ammonia and Acetone (Heintz, A. 174, 133; 198, 42). Two bases result from the action of ammonia upon acetone : diacetonamine and triacetonamine. It may be supposed that the ammonia causes the acetone to condense, just as the alkalies and alkaline earths do, and that acetone ammonia, an intermediate product, combines with the ammonia, or ammonia with mesityl oxide, to yield diacetonamine, which by further treatment with acetone is changed to triacetonamine, or when acted upon by aldehydes passes into vinyldiacetonamine (B. 17, 1788), or into a d-lactam through the agency of cyanacetic ester (B. 26, R. 450) : SJ! 3 >C r= CH . CO . CH 3 -f- NH, = SS 3 >C CH 2 . CO . CH 3 3 NH 2 Mesityl Oxide Diacetonamine O.CH, + CO C CH 2 .CO.CH 2 .CH.CH S + H 2 O NH Vinyldiacetonamine. Diacetonamine is a colorless liquid, not very soluble in water. When distilled it decomposes into mesityl oxide and NH 3 ; conversely, mesityl oxide and NH 3 com- bine to form diacetonamine (B. 7, 1387). It reacts strongly alkaline and is an amide base, forming crystalline salts with one equivalent of acid. If potassium nitrite be allowed to act on the HCl-salt, diacetone alcohol, (CH,) 2 C(OH) . CH 2 . CO . CH 3 , results ; this loses water and becomes mesityl oxide. For the urea derivatives of acetone, consult B. 27, 377. A chromic acid mixture oxidizes diacetonamine to amidoisobutyric acid, (CH 3 ) 2 . - C(NH 2 ) . CO 2 H(Propalanine),and amidoisovaleric acid,(CH 3 ) 2 C(NH 2 )CH 2 . CO 2 H. Triacetonamine crystallizes in anhydrous needles, melting at 39.6. With one molecule of water it forms large quadratic plates, fusing at 58. It is an imide base (p. 167) with feeble alkaline reaction ; potassium nitrite converts its HCl-salt into the nitroso-amine compound, C 9 H 16 (NO)NO, which fuses at 73 and passes into phorone when boiled with caustic soda. Hydrochloric acid regenerates triaceton- amine from the nitroso-derivative. By the addition of 2H to triacetonamine, converting the CO group into CH . OH, there results an alkamine, C 9 H 19 NO, which may be viewed as hydroxy-tetramethyl piperidine. By the abstraction of water from this, the base C 9 H, 7 N, triacetonine, boiling at 146, results. This approaches tropidine, C 8 H 13 N, very closely (B. 16, 2236; 17, 1788). TfMetkyl-trutcetonaminevoA allied bases (B. 28, R. 160) are formed when phorone is treated with primary amines. C. Ketoximes (V. Meyer). In general, the ketoximes are formed with greater difficulty than the aldoximes. It is usually best to apply the hydroxylamine in a strongly alkaline solution (B. 22, 605 ; A. 241, 187). They are also produced when the pseudonitriles are re- 220 ORGANIC CHEMISTRY. duced by free hydroxylamine or potassium sulphydrate (B. 28, 1367 ; 29, 87, 98). They are very similar in properties to the aldoximes. Acids resolve them into their components, while sodium amalgam and acetic acid convert them into primary amines (p. 161). They are charac- teristically distinguished from the aldoximes by their deportment toward acid chlorides or acetic anhydride, yielding in part acid esters, and, again, by the same reagents, as well as by HC1 in glacial acetic acid, being changed to acid amides (Beckmann's transposition, B. 20, 506, 2580 ; compare also B. 24, 4018) : CH CH CH 3 > CH = NOH ~~ ~~^ CH 3 ' CO ' NHCH 2 CH 2 CH 3- Methyl Propyl Ketoxime Acetpropylamide. Nitrogen tetroxide converts the ketoximes into pseudonitroh (p. 158). Ketoximes combine with hydrocyanic acid to form nitriles of a-amidoxyl carboxylic acids (B. 29, 62). Acetoxime, (CH 3 ) 2 C: NOH, melting at 59-60 and boiling at 135, smells like chloral. It dissolves readily in water, alcohol, and ether (B. 20, 1505). Hypochlorous acid converts acetoxime into hypochlorous ester, (CH 3 ) 2 C : N . OC1, a liquid with an agreeable odor. It boils at 134. It explodes, however, when rapidly heated (B. 20, 1505). The hydroxyl hydrogen present in acetoxime may be replaced by acid radicals through the agency of acid chlorides or anhydrides (B. 24, 3537). With sodium alcoholate, the sodium derivative results, which yields the alkyl ethers, (CH 3 ) 2 - C : N . OR, when acted upon by the alkylogens. On boiling these ethers with acids, acetone and alkylized hydroxylamines, NH 2 OR (B. 16, 170), are produced. The higher acetoximes show a perfectly analogous deportment. Methyl-ethyl-ketoxime boils at 152-153. Methyl-n-propyl Ketoxime is an oil with agreeable odor. Methyl-isopropyl Ketoxime boils at 157-158. Methyl-n-butyl Ketoxime boils at 185. Methyl tertiary butyl Ketoxime melts at 74 75' "R-Butyronoxime boils at 190195. Isobutyronoxime melts at 68 and boils at 181-185. Methylnonyl Ketoxime melts at 42. Caprylonoxime melts at 20. Nonyloxime melts at 12. Lauronoxime, (C 11 H 23 ) 2 C : N . OH, melts at 39-40. Myristonoxime, (C 13 H 27 ) 2 C: N , OH, melts at 51. Palmitonoxime, (C ]5 H 31 ) a - C : N . OH, melts at 59. Stearonoxime, (C 17 H 35 ) 2 C : N . OH, melts at 62-63. D. Ketazines (Curtius and Thun). An excess of hydrazine acting upon the ketones produces the unstable, secondary unsymmetrical hydrazines, which even in the cold readily become ketazines, quite stable toward alkalies (B. 25, R. 80). Dimethylketazine in contact with maleic acid changes to the isomeric trimethyl pyrazoline (B. 27, 770) : (CH 3 ) 2 C = N N = CCH 8 (CH 3 ) 2 C = N *" HN CH 2 C(CH,V Bisdimethylazimethylene, dimethylketazine, [(CH 3 ) 2 C: N ] 2 , boils at 131; Bismethylethylazimethylene boils at 168-172 ; Bismethylpropylazimethyl- ene boils at 195-200.; Bismethylhexylazimethylene boils at 290 ; Bisdiethyl- azimethylene boils at 190-195. E. Ketone-phenylhydrazones (E. Fischer, B. 16, 66i; 17, 576; 20, 513; 21, 984). These compounds result by the action of phenylhydrazine upon the ketones. The phenylhydrazine is added to the ketone until a sample of the mixture no longer reduces an alkaline copper solution. They behave like the aldehyde phenylhydrazones (p. 207). OLEFINE AND DIOLEFINE KETONES. 221 Acetone-phenylhydrazone, (CH 3 ) 2 C: N 2 HC 6 H 5 , melts at 16 and boils at 165 (91 mm.). Methyl-n-propylketone-phenylhydrazone, (CH 3 )(C S H 7 )C: N 2 HC 6 H 5 , boils at 205-208 (loo mm.). 36. OLEFINE AND DIOLEFINE KETONES. Such bodies have been obtained by the direct condensation of acetone : mesityl oxide and phorone (p. 214). They have also resulted from i,3-ketone alcohols by the elimination of water. Ethidene Acetone, CH 3 CH = CH . CO . CH 3 , boils at 122. It has a pene- trating odor like that of crotonaldehyde. It is formed when hydracetylacetone (see this) is boiled with acetic anhydride (B. 25, 3166). Heptachlorethidene Acetone, CHC1 2 CC1 = CC1 . CO . CC1 3 , boils at 182-185 (13-15 mm.). It results when trichloracetyl tetrachloracetone is heated with water (B. 25, 2695). Mesityl Oxide, (CH 3 ) 2 C = CH . CO. CH 3 , boiling at 130, is a liquid smelling like peppermint. Phorone, (CH 3 ) 2 C = CH . CO . CH = C(CH 3 ) 2 , melts at 28 and boils at 196. These are formed simultaneously-on treating acetone with dehydrating agents, e.g., ZnCl 2 , H 2 SO 4 , and HC1. Hydrochloric acid is best adapted for this purpose, the acetone being saturated with it, while it is cooled. The hydrochloric acid addition products, (CH 3 ) 2 CC1 . CH 2 . COCH 3 and (CH 8 ) 2 CC1 . CH 2 . CO . CH 2 .- CC1(CH 3 ) 2 , are decomposed by caustic alkalies, and the mesityl oxide and phorone then separated by distillation. When acetone is condensed by lime or sodium ethylate there is produced along with the mesityl oxide a cyclic ketone isomeric with phorone. It is called isophorone. Camphor-phorone is also isomeric with these two phorones. Mesityl oxide combines with ammonia to diacetonamine (p. 219), and with hydrazine to trimethyl pyrazoline. Mesityl oxide is also produced when diacetone alcohol (see this) and diacetonamine (p. 2\g] are heated alone ; also to- gether with acetone when phorone is heated with dilute sulphuric acid, which eventually causes it to break down into two molecules of acetone, as the result of water absorptioa(A. 180, l) ; also by the action of isobutylene upon acetic anhy- dride in the presence of a little ZnCl 2 (B. 27. R. 942). Mesityl oxide takes up two and phorone four bromine atoms ; both yield oximes with hydroxylamine. Historical. Kane discovered mesityl oxide in 1838, when he obtained it, together with mesitylene, by the action of concentrated sulphuric acid on acetone. At that time he regarded acetone as alcohol, and called it mesitalcohol. In mesityl oxide and mesitylene, Kane thought he had discovered bodies which bore the same relation to mesityl alcohol or acetone that ethyl ether or ethyl oxide and ethylene bore to ethyl alcohol. Kekule developed the formula (CH 3 ) 2 . C = CH . CO . CH 3 for mesityl oxide, which had been suggested by Claisen. Baeyer discovered phorone, and Claisen assigned to it the formula (CH 3 ) 2 C CH . CO . CH = C(CH 3 ) 2 (A. 180, i). Methylheptenone, (CH 3 ) 2 C =CH . CH 2 . CH 2 . CO . CH 3 , boiling at 173, occurs in many ethereal oils, e. g. y citral, geranium oil, etc. It is produced in the distillation of cineolic anhydride. It has been synthesized by treating the reaction- product resulting from sodium acetonylacetone and amylene dibromide, (CH 3 ) 2 CBr.- CM, . CH 2 Br, with caustic soda (B. 29, R. 590). It is a liquid with a penetrating odor resembling that of amyl acetate. Potassium permanganate decomposes it into acetone and laevulinic acid. Zinc chloride converts it into m-dihydroxylene (A. 258, 323; B. 28, 2115, 2126). Isoamylidene acetone, (CHACH . CH 2 . CH = CH- COCH,, boils at 180 (B. 27, R. 121). Diallylacetone, CH 2 = CH . CH 2 . CH 2 . CO . CH 2 . CH 2 . CH = CH 2 , boiling at 116 (70 mm.), is obtained from diallyl-acetone dicarboxylic ester (compare oxetones). Pseudoionone is a diolefine-ketone, and it will be described together with the olefine terpenes. 222 ORGANIC CHEMISTRY. 4. MONOBASIC ACIDS. The organic acids are characterized by the atomic group, CC3 . OH, called carboxyl. The hydrogen of this can be replaced by metals and alcohol radicals, forming salts and esters. These organic acids may be compared to the sulphonic acids, containing the sulpho-group, SO, . OH. The number of carboxyl groups present in them determines their basicity, and distinguishes them as mono-, di-, tri-basic, etc., or as mono , di- and tri-carboxylic acids : CH S .CO,H C Acetic Acid Malonic Acid Tricarballylic Acid. (Monobasic) (Dibasic) (Tribasic). We can view the monobasic saturated acids as combinations of the carboxyl group with alcohol radicals; they are ordinarily termed fatty acids. They correspond to the saturated primary alcohols and alde- hydes. The unsaturated acids of the acrylic acid and propiolic acid series, corresponding to the unsaturated primary alcohols and alde- hydes, are derived from the fatty acids by the exit of two and four hydrogen atoms. They are distinguished as : A. Paraffin monocarboxylic Acids, C n H 2n O 2 , formic acid or acetic acid series. B. Olefine monocarboxylic Acids, C n H 2n _ 2 O 2 , oleic or acrylic acid series. C. Acetylene monocarboxylic Acids, C n H 2n _ 4 O 2 , propiolic acid series. D. Diolefine carboxylic Acids, C n H 2n _ 4 O 2 . Nomenclature. The "Geneva nomenclature" deduces the names of the carboxylic acids, just like the alcohols (p. in), the aldehydes (p. 190), and the ketones (p. 211), from the corresponding hydro- carbons; thus formic acid is [methanic acid] and acetic acid is [ethanic acid], etc. The radical of the acid is the residue in combination with the hydroxyl group : CH 3 . CO CH 3 . CH 2 . CO CH 3 . CH 2 . CH 2 . CO Acetyl Propionyl Butyryl. The names of the trivalent hydrocarbon residues, which in the acid residues are united with oxygen, are indicated by the insertion of the syllable "en " into the names of the corresponding alcohol radicals: CH S . C= CH 3 . CH 2 . C= CH 3 . CH 2 . CH 2 . C= Ethenyl Propenyl n-Butenyl. The group CH=, however, is not only called the methenyl group, but also the methine group. MONOBASIC ACIDS. 223 Review of the Derivatives of the Monocarboxylic Acids. Numerous classes of bodies can be derived by changes in the car- boxyl group. In connection with the fatty acids mention will only be made of the salts. The other classes of derivatives will be con- sidered as such after the fatty acids. They are : (1) The esters, resulting from the replacement of hydrogen in the carboxyl group by alcohol radicals (p. 253). (2) The chlorides (bromides and iodides), which are compounds of the acid radicals with the halogens. (3) The acid anhydrides (p. 259), compounds of the acid radicals with oxygen. (4) The acid peroxides (p. 261). (5) The /to acids (p. 261), compounds of the acid radicals with SH. (6) The acid amides (p. 262), compounds of the acid radicals with NH 2 . (7) The acid nitriles (p. 266). Hence acetic acid yields the following : i. CH 3 .CO 2 .C 2 H 5 2. CH 3 .COC1 3. (CH 3 . CO) 2 O 4. (CH 3 .CO) 2 O 2 Acetic Ethyl Ester Acetyl Chloride Acetic 'Anhydride Acetyl Peroxide 5. CH 3 . COSH 6. CH 3 . CONH 2 7. CH 3 . C=N Thiacetic Acid Acetamide Acetonitrile. Associated with the acid haloids, acid amides, and nitriles are : (8) acid hydrazides (p. 265) ; (9) amide chlorides (p. 268) ; (10) imide chlorides (p. 268) ; (ll) imido- ethers (p. 269) ; (12) thioamides (p. 269); (13) amidines (p. 270) ; (14) hydroxamic acids (p. 270) ; (15) nitrolic acids (p. 270) ; (16) amidoximes (p. 271). 8. CIT 3 . CO . NH . NIT 2 9. CH 3 . CC1 2 . NH 2 10. CH 3 . CC1 : NH Acetylhydrazine Acetamide Chloride Acetimide Chloride (unstable) (unstable) O . C 2 H 5 - NH 2 NH ii. CH 3 .C< 12. CH 3 .C< 13. CH 3 .C Acetoimidoethyl Ether Thioacetamide Acetamidine /OH ,NO 2 .NH 2 14. CH 3 . C/ 15. CH 3 . C/ 16. CH 3 . C/ Ethyl Hydroxamic Acid Ethyl Nitrolic Acid Acetamidoxime. (P- 158) Numerous derivatives are also obtained by the replacement of the hydrogen atoms in the radical combined with hydroxyl by other atoms or groups. Only the halogen substitution products will be de- scribed under the fatty acids, after the discussion of the various classes mentioned in the preceding paragraphs. The fatty acids can be recovered from all of the above classes of derivatives by simple reactions. It has already been indicated, under the oxygen derivatives of the methane hydrocarbons, that: aldehydes, ketones, and carboxylic acids may be considered as anhydrides of non-existing diacid or triacid alcohols, in which the hydroxyl groups are attached to the same carbon atom (p. 108). In this exposition the alcohols and ketones 224 ORGANIC CHEMISTRY. were especially recalled, because there were, for example, under the acetals (p. 200) and under the orthoketone alkyl ethers (p. 217), ethers of just such glycols or ortho-aldehydes, non-existent ordinarily in the free state, and of orthoketones, while chloral hydrate itself was such a glycol. The trihydric alcohols, corresponding to the carboxylic acids, can not exist, but ethers of them are known. The hypothetical, trihydric alcohols, of which the carbonic acids may be considered anhydrides, have been called ortho acids, suggesting tribasic phosphoric acid as orthophosphoric acid (A. 139, 114; J. (1859) 152; B. 2, 115). This designation has also been conveyed to the orthoaldehydes and ortho- ketones. It is customary to speak of "hypothetical orthoformic acid" and of "orthoformic esters," the esters of tribasic formic acid, of formic acid, which, in reference to the relation of orthophosphoric to meta- phosphoric acid, PO(OOH), might be termed metaformic acid, and of formic acid esters : /OH /OC 2 H 5 .OH /OC,H, HC^-OH HC^OC 2 H 5 CH< CH< \OH \OCX ^ ^O Orthoformic Acid Orthoformic Ethyl Formic Acid Formic Ethyl Ester Ester. The chloride, bromide, and iodide corresponding to orthoformic acid are chloroform, bromoform, and iodoform. It is only in the case of formic acid that the ortho-acid derivatives require a special designation. They will be discussed immediately following the derivatives of the ordinary formic acid. A. MONOBASIC SATURATED ACIDS, PARAFFIN MONO- CARBOXYLIC ACIDS, C n H 2n+1 .C0 2 H. Formic acid, H . COOH, is the first member of this series. The radical HCO, in union with hydroxyl, is called formyl. This acid is distinguished from all its homologues and the unsaturated monocar- boxylic acids, in that it manifests not only the character of a mono- basic acid, but also that of an aldehyde. To express in a name its aldehyde character the acid might be designated oxyformaldehyde, From a chemical standpoint, this acid stands closer to glyoxylic acid, CHO . CO 2 H (see this) than to acetic acid. Therefore, formic acid and its derivatives will be treated before acetic acid and its homo- logues are discussed. FORMIC ACID AND ITS DERIVATIVES. It is not only the aldehyde character which distinguishes formic acid from acetic acid and its homologues, but it is also the absence of a chloride and anhydride, corresponding to acetyl chloride (see this) FORMIC ACID AND ITS DERIVATIVES. 225 and acetic anhydride (see this). The withdrawal of water from formic acid leads to the formation of carbon monoxide; this is a transformation manifested by none of the higher homologues. Prussic acid (hydrocyanic acid), the nitrile of formic acid, has an acid nature, and therein differs from the indifferent nitriles of the homologous acids. Formic acid is twelve times stronger than acetic acid. The affinity constants from the electric conductivity show this (Ostwald). To formic acid will be appended carbon monoxide, and its nitrogen- containing derivatives, the isonitriles or car by famines, C = N R', and fulminic acid. Formic Acid, HCO . OH (Acidum formicum), is found free in ants, in the case-worm of Bombyx processioned, in stinging nettles, in shoots of the pine, in various animal secretions (perspiration), and may be obtained from these substances by distilling them with water. It is produced artificially according to the usual methods: (1) By the oxidation of methyl alcohol and formaldehyde : o o H . CH 2 OH - > H . CHO >- H . CO 2 H. (2) By heating hydrocyanic acid with alkalies or acids : HCN + 2H 2 = HCO . OH -f NH 3 . (3) By boiling chloroform with alcoholic potash (Dumas) : CHC1 3 + 4 KOH = HCO . OK -f 3 KC1 -f 2H 2 O. (4) From chloral and (5) from propargylic aldehyde (p. 209) and caustic potash (Liebig) : CC1 8 . CHO + NaOH = HCOONa -f HCC1 3 . Worthy of mention is (6) the direct production of formates by the action of CO upon concentrated potash at 100. The reaction occurs more easily if soda-lime at 2oo-22o (Berthelot, A. 97, 125 ; Geu- ther, A. 202, 317 ; Merz and Tibirica, B. 13, 718) be employed : CO -f NaOH = HCO . ONa. (7) By action of acids upon isocyanides or carbylamines (p. 237) : CN . C 2 H 5 -f 2H 2 = H . C0 2 H + C 2 H 5 NH 2 . (8) From fulminic acid by means of concentrated hydrochloric acid (see formyl chloridoxime, p. 233). Hydroxylamine is formed simul- taneously : C = N . OH -f 2H 2 O + HC1 = H . CO 2 H + NH 2 OH . HC1. (9) By letting moist carbon dioxide act upon potassium : 3CO 2 -f 4K + H 2 O = 2HCO . OK -f CO 3 K 2 (Kolbe and Schmitt, A. 119, 251). Formates are also produced in the action of sodium amalgam upon a concentrated aqueous ammonium carbonate solution, or with the same reagent upon aqueous pri- mary carbonates ; likewise on boiling zinc carbonate with caustic potash and zinc dust. 226 ORGANIC CHEMISTRY. (10) The most practical method of preparing formic acid consists in heating oxalic acid. This decomposition is accelerated by the presence of glycerol (Berthelot). Oxalic acid treated alone decomposes into carbon dioxide and formic acid, or carbon monoxide and water ; the latter decomposition preponderates : COOH HCO 2 H + CO 2 COO H CO + H 2 + C0 2 . When, however, (C 2 O 4 H 2 -{- 2H 2 O) is added to moist concentrated glycerol and the whole heated to 100-110, oxalic acid parts with its water of crystallization and unites with the glycerol to form glycerol formic ester : rOH rOH C 3 H 5 j OH + C 2 4 H 2 = C 3 H 5 | OH + CO 2 + H 2 O. On further addition of crystallized oxalic acid the latter again breaks up into anhy- drous acid and water, which converts the glycerol formic ester into glycerol and formic acid : C $ H 5 (OH) 2 . (O . CHO) + H 2 = C 3 H 5 (OH) 3 -f CHO . OH. At first the acid is very dilute, but later it reaches 56 per cent. If anhydrous acid be employed at the beginning, a 95-98 per cent, formic acid is produced. To obtain anhydrous acid, the aqueous product is boiled with lead oxide or lead carbonate. The lead formate is then decomposed, at 100, by a current of hydrogen sulphide. Or, formic acid of high percentage is dehydrated by means of boric acid (B. 14, 1709). Formic acid is a mobile liquid with a specific gravity of 1.22 at 20 and boils at 100.6 (760 mm.). It becomes crystalline at o, and fuses at -j-8.6 . It has a pungent odor and causes blisters on the skin. It mixes in all proportions with water, alcohol and ether, and yields the hydrate 4CH 2 O 2 -f 3^0, which boils at 107.1 (760 mm.) and dissociates into formic acid and water. Concentrated, hot sul- phuric acid decomposes formic acid into carbon monoxide and water. A temperature of 160 suffices to break up the acid into carbon dioxide and hydrogen. The same change may occur at ordinary temperatures by the action of pulverulent rhodium, iridium and ruthenium, but less readily when platinum sponge is employed. According to its structure formic acid is also an aldehyde, as it con- tains the group CHO; this would account for its reducing property, its ability to precipitate silver from a hot neutral solution of silver nitrate, and mercury from mercuric nitrate, the acid itself oxidizing to carbon dioxide : /H o /OH HO . C< - - HO . C/ ^ C0 2 + H 2 0. ^O ^O Formates, excepting the sparingly soluble lead and silver salts, are readily soluble in water. Lead formate, (HCO 2 ) 2 Pb, crystallizes in beautiful needles and dissolves in 36 parts of cold water. Silver formate, HCO 2 Ag, rapidly blackens on exposure to light. FORMIC ACID AND ITS DERIVATIVES. 227 Decomposition of Formates. I. The alkali salts, heated carefully to 250, become oxalates with evolution of hydrogen : CO. OK 2CHO . OK = I + H 2 . CO. OK 2. By ignition of potassium formate with an excess of alkali it decomposes with the formation of a carbonate and the liberation of pure hydrogen, H . CO 2 K -f- KOH - K 2 C0 3 + H 2 . 3. The ammonium salt, heated to 230, passes into formamide : H . C0 2 NH 4 l!^_-^ H.COXH 2 . 230 4. The silver salt and mercury salt, when heated, decompose into metal, carbon dioxide and formic acid : 2CHO 2 Ag = 2Ag -f CO 2 + H . CO 2 H. 5. The calcium salt, when heated with the calcium salts of higher fatty acids, yields aldehydes (p. 18.8). Monochlorformic acid, CC1O . OH, is regarded as chlor-carbonic acid. It will be discussed after carbonic acid. Esters of Formic Acid. Liquids with an agreeable odor. They are prepared from (i) formic acid, alcohol and hydrochloric or sul- phuric acid; (2) from sodium formate and alkyl sulphates; (3) from glycerol, oxalic acid and alcohols. Methyl Formic Ester boils at 32.5. Perchlor-methyl formic ester, CC1O 2 . CU 3 , boils at 180-185. Heated to 305 it breaks up into carbonyl chloride, C 2 C1 + O 2 = 2COC1 2 . Aluminium chloride converts it into CC1 4 and CO 2 . Ethyl Formic Ester boils at 54.4. This ester serves in the manufacture of artificial rum and arrack, and for the union of the formyl group with organic radicals (see formyl acetone, etc.). The r\-propyl ester boils at 81. The n-butyl ester boils at 107. For higher esters consult A. 233, 253. The allyl ester boils at 82-83. Formamide, CHO . NH 2 , the amide of formic acid (compare acid amides) is obtained (i) by heating ammonium formate to 230 (B. 12, 973 j J 5 980), or (2) ethyl formic ester with alcoholic ammonia to 100; (3) by boiling formic acid with ammonium sulphocyanide (B. 16, 2291). It is a liquid, readily soluble, in water and alcohol, and boils with partial decomposition at i92-i95. Heated rapidly it breaks up into CO and NH 3 ; P->O 5 liberates HCN from it. It combines with chloral (p. 197) to form chloral formamide, CC1 3 . CH(OH)NHCHO, melting at 114-115, and finding use as a narcotic. Mercuric oxide dissolves in it with the formation of mercury formamide, (CHO . - NH) 2 Hg. This is a feebly alkaline liquid, sometimes applied as a subcutaneous injection. Ethyl Formamide, CHO . NH . C 2 H 5 , is obtained from ethyl formic ester; also by distilling a mixture of ethylamine with chloral : CC1 3 . CHO + NH 2 . C 2 H 6 = CHO . NH . C 2 II 5 + CC1 8 H. It boils at 199. 228 ORGANIC CHEMISTRY. Allyl Formamide boils at 109 (15 mm.) (B. 28, 1666). Formyl Hydrazine, HCONHNH.,, melting at 54, is obtained from formic ester and hydrazine. It yields triazole (B. 27, R. 801) when heated with formamide. Diformyl Hydrazine, HCONH . NH . COH, melting at 106, is ob- tained from an excess of formic ester and hydrazine, heated to 130 (B. 28, R. 242). Its lead salt and ethyl iodide yield Diformyl Diethyl- hydrazine (B. 27, 2278). Hydrocyanic Acid, Prussic Acid, Formonitrile, CNH, the nitrile of formic acid (see acid nitriles), is a powerful poison. It occurs free in an accumulated condition in all parts of the Java tree Pangium edule (B. 23, 3548). It is obtained (i) from amygdalin (see this), a glucoside contained in bitter almonds, which, under favorable conditions, takes up water and breaks down into prussic acid, grape sugar, and bitter almond-oil or benzaldehyde (Liebig and Wohler, A. 22, i). An aqueous solution, thus obtained, containing very little hydrocyanic acid, constitutes the officinal aqua amygdalarum amar- arum; its active ingredient is prussic acid. (2) By the action of phos- phorus pentoxide upon formamide ; (3) synthetically, by passing the electric spark through a mixture of acetylene and nitrogen (Berthelot) ; (4) from cyanogen and hydrogen under the influence of the silent electric discharge; (5) when chloroform is heated, under pressure, with ammonia; (6) upon boiling formoxime (p. 206) with water: I. C 20 H 27 NO n + 2H 2 = CNH + < Amygdalin B _ TTPONFT *~- /-xTtr i C 6 H 5 CHO 4- 2C 6 H 12 6 enzaldehyde Grape Sugar. H 2 f- 3 NH 4 C1 hH 2 0. ^. rx^v^xNjrio 3. CH=CH 4- 4. CN . CN + 5. HCC1, + 5: 6. H 2 C = N . OH f^ \-/J-^l -Li -T , N 2 = 2CNH H 2 = 2CNH NH 3 =CNNH 4 - = CNH - Hydrogen cyanide is prepared from metallic cyanides, particularly yellow prussiate of potash or potassium ferrocyanide, by the action of dilute sulphuric acid : 2Fe(CN) 6 K 4 + 3 S0 4 H 2 = Fe 2 (CN) 6 K 2 + 3 SO 4 K 2 + 6CNH. The aqueous prussic acid obtained in this way is dehydrated by distillation over calcium chloride or phosphorus pentoxide. Historical. Scheele discovered prussic acid in 1782. Gay-Lussac, in 1811, ob- tained it anhydrous, in the course of his memorable investigations upon the radical cyanogen. In hydrogen cyanide he recognized the hydrogen derivative of a radical, consisting of carbon and nitrogen, for which he suggested the name cyanogene (ttvavog, blue, yevvdu, to produce]. Properties. Anhydrous hydrocyanic acid is a mobile liquid, of specific gravity 0.697 at 18, and becomes a crystalline solid at 15. It boils at -f-26.5. Its odor is peculiar, and resembles that of oil of fitter almonds. The acid is extremely poisonous. FORMIC ACID AND ITS DERIVATIVES. 229 It is a feeble acid, and imparts a faint red color to blue litmus. Carbon dioxide decomposes its alkali salts. Like the haloid acids, it reacts with metallic oxides, producing metallic cyanides. From solu- tions of silver nitrate it precipitates silver cyanide, a white, curdy precipitate. Transpositions. (i) The aqueous acid decomposes readily upon standing, yielding ammonium formate and brown substances. The presence of a very slight quantity of stronger acid renders it more stable. When warmed with alkalies or mineral acids it breaks up into formic acid and ammonia: CNH + 2H 2 O = CHO . OH + NH 3 . (2) Dry prussic acid combines directly with the gaseous halogen hydrides (p. 232) to form crystalline compounds. With hydrochloric acid it probably yields Formimide chloride, (H . CC1 = NH) 2 HC1 (B. 16, 352). The acid also unites with some metallic chlorides, ^.,Fe 2 Cl 6 , SbCl 5 . (3) Nascent hydrogen (zinc and hydrochloric acid) reduces it to methylamine (p. 162). (4) When hydrogen cyanide unites with aldehydes and ketones, the double union between carbon and oxygen in the latter compounds is severed, and cyanhydrins, the nitriles of a-oxyacids, are produced. These, by this means, are obtained by a nucleus synthesis. This rather important synthesis has become especially interesting for the up- building of the aldoses, to which class of derivatives grape-sugar belongs. (5) Prussic acid, or potassium cyanide, adds itself to many a/5-unsat- urated carboxylic acids, producing thereby saturated nitrilo carboxylic acids (A. 293, 338). For further addition reactions of prussic acid, compare formimido ether (p. 232) and isouretine (p. 233). Constitution. The production of prussic acid from formamide on the one side, and its reconversion into ammonium formate, are proofs positive of its being the nitrile of formic acid (see acid nitriles). Its formation from chloroform and from acetylene argue also for the formula H . CEEN. The replacement of hydrogen, combined with carbon, by metals is shown also by acetylene (p. 97) and other car- bon compounds containing negative groups, e. g. , the nitro-ethanes (p. 154). How- ever, on replacing the metal atoms in the salts by alkyls, two classes of derivatives are obtained. The one series has the alkyls united to carbon, as required by the formula H . CEEN : nitriles of monocarboxylic acids, e. g., CH 3 . CN. In the other class the alkyls are joined to nitrogen : isonitriles or carbylamines, e. g., C = N . CH 3 . The latter are nitrogen-containing derivatives of carbon monoxide, and will be dis- cussed after this body. In many respects the deportment of prussic acid recalls that of the isonitriles, hence in recent years the formula HN C has also been brought forward for it, and many of the reactions of potassium cyanide conform better with the isonitrile formula, K . N C, than with K . CEEN, the formula usually assigned to this salt (A. 287, 263). The formation of acetonitiile from prussic acid and diazomethane argues for the nitrile formula of hydrogen cyanide (B. 28, 857). Detection. To detect small quantities of free prussic acid or its soluble^ salts, saturate the solution under examination with caustic potash, add a solution of a 230 ORGANIC CHEMISTRY. ferrous salt, containing some ferric salt, and boil for a short time. Add hydrochloric acid to dissolve the precipitated iron oxides. If any insoluble Prussian blue should remain, it would indicate the presence of hydrocyanic acid. The following reaction is more sensitive. A few drops of yellow ammonium sulphide are added to the prussic acid solution, and this then evaporated to dryness. Ammonium sulpho- cyanide will remain, and if added to a ferric salt, will color it a deep red. Polymerization of Prussic Acid. When the aqueous acid stands for some time in contact with caustic alkalies, or with alkaline carbonates, or if prussic acid made from the anhydrous acid be mixed with a small piece of potassium cyanide, not only brown substances separate, but also white crystals, soluble in ether, and having the same percentage composition as hydrocyanic acid. Inasmuch as they break down, on boiling, into glycocoll, NH 2 . CH 2 . CO 2 H, carbon dioxide and ammonia, they are assumed to be the nitrile of atnidotna Ionic acid, (CN) 2 CHNH 2 (B. 7, 767). They decompose at 180, wiih explosion and partial reformation of prussic acid. Salts of Hydrocyanic Acid. Cyanides and Double Cyanides The importance of the cyanides and double cyanides in analytical chemistry explains the reason for the discussion of prussic acid and its salts in inorganic text-books. In organic chemistry the metallic cyanides serve for the introduction of the cyanogen group into carbon compounds (compare acid nitrile -j, a-ketonic acids , etc.). The alkali cyanides may be formed by the direct action of these metals upon cyanogen gas ; thus, potassium burns with a red flame in cyanogen, at the same time yielding potassium cyanide, C 2 N 2 -f- K 2 = 2CNK. They are also produced when nitrogenous organic substances are heated together with alkali metals. The strongly basic metals dissolve in hydrocyanic acid, forming cyanides. A more common procedure is to act with the acid upon metallic oxides and hydroxides : CNH + KOH = CNK + H 2 O; 2CNH + HgO = Hg(CN), + H 2 O. The insoluble cyanides of the heavy metals are obtained by the double decomposition of the metallic salts with potassium cyanide. The cyanides of the light metals, especially the alkali and alkaline earths, are easily soluble in water, react alkaline, and are decomposed by acids, even carbon dioxide, with elimination of hydrogen cyanide; yet they are very stable, even at a red heat, and sustain no change. The cyanides of the heavy metals, however, are mostly insoluble, and are only decomposed, or not at all, by the strong acids. When ignited, the cyanides of the noble metals suffer decomposition, breaking up into cyanogen gas and metals. The following simple cyanides are especially important in organic chemistry : Potassium Cyanide, CNK. Consult v. Richter's " Inorganic Chemistry" for method of preparation, properties, and technical ap- plications of this salt. air Its aqueous or alcoholic solution becomes brown in color on exposure to the it decomposes rapidly, on boiling, into potassium formate and ammonia. When fused in the air, as well as with easily reducible metallic oxides, the salt absorbs oxygen and is converted into potassium isocyanate (see this). When acid haloids or alkyl sulphates are heated with potassium cyanide, acid nitriles with varying amounts of isomeric carbylamines or isonitriles are produced. Many organic halogen substi- FORMIC ACID AND ITS DERIVATIVES. 23! tution products are transposed into nitriles through the agency of potassium cyanide. Ethyl hypochlorite and potassium cyanide yield cyanimidocarbonic ester a reaction which argues for the isonitrile formula of potassium cyanide (A. 287, 274). Ammonium Cyanide, NH 4 CN, is formed by the direct union of CNH with ammonia, by heating carbon in ammonia gas, by the action of ammonia upon chloro- form (p. 228). by the action of the silent electric discharge upon methane and nitrogen, and by conducting carbon monoxide and ammonia through red-hot tubes. It is best prepared by subliming a mixture of potassium cyanide or dry ferrocyanicle with ammonium chloride. It consists of colorless cubes, easily soluble in alcohol, and subliming at 40, with partial decomposition into NH 3 and CNH. When pre- served it becomes dark in color and decomposes. It yields methylene amido-aceto- nitrile (compare glycocoll). Mercuric Cyanide, Hg(CN) 2 , is obtained by dissolving mercuric oxide in hydro- cyanic acid, or by boiling Prussian blue (8 parts) and mercuric oxide (I part) with water until the blue coloration disappears. It dissolves readily in hot water (in 8 parts cold water), and crystallizes in bright, shining, quadratic prisms. When heated it yields cyanogen and mercury. It forms acetyl cyanide with acetyl chloride (see pyroracemic acid). Silver Cyanide, AgCN, combines with alkyl iodides to yield addition products, which pass in{o isonitrile when they are heated (p. 236). The chief use of potassium cyanide is in the preparation of acid nitriles of various kinds. This is done by bringing it into double decompositions with alkylogens, alkyl sulphates, and halogen substitu- tion products of the fatty acids. In many instances mercury cyanide or silver cyanide is preferable, e.g., in the formation of a-ketonic nitriles from acid chlorides or bromides. It is interesting to note that by the interaction of alkyl iodides and silver cyanide isonitriles or carbylamines are formed ; in them the alcohol radical is joined to nitrogen. (See page 237 for the explanation.) Compound Metallic Cyanides. The cyanides of the heavy metals insoluble in water dissolve in aqueous potassium cyanide,, forming crystallizable double cyanides, which are soluble in water. Most of these compounds behave like double salts. Acids decompose them in the cold, with disengagement of hydrocyanic acid and the precipitation of the insoluble cyanides: AgCN . KCN + HN0 3 = AgCN + KNO 3 + CNH. In others, however, the metal is in more intimate union with the cyanogen group, and the metals in these cannot be detected by the usual reagents. Iron, cobalt, platinum, also chromium and man- ganese in their ic state, form cyanogen derivatives of this class. The stronger acids do not eliminate prussic acid from them, even in the cold, "but hydrogen acids are set free, and these are capable of pro- ducing salts : Fe(CN) 6 K 4 + 4HC1 Fe(CN) 6 H 4 + 4KC1. Potassium Ferrocyanide Hydroferrocyanic Acid. Many chemists refer these complex metallic acids to hypothetical, polymeric prussic acids : H_C=rN H_C=N C H II I II N=C_H N-CH-N Di-hydrocyanic Acid Tri-hydrocyanic Acid. 232 ORGANIC CHEMISTRY. p C 2 N 2 K C(N0 2 ) 3 H. It is a thick, colorless oil, solidifying below 15, and exploding with violence when rapidly heated. Formyl-trisulphonic Acid, Methine Trisulphonic Acid, CH(SO 3 H) 3 , is pro- duced by the action of sodium sulphite upon chloropicrin, CC1 3 (NO 2 ) (see this), and when fuming sulphuric acid acts upon calcium methyl-sulphonate (p. 204). The acid is very stable, even in the presence of boiling alkalies. In this connection may be mentioned also dibromnitroinethrtne (p. 157), nitro- methane disulphonic acid (A. 161, 161), and oxymethane disulphonic acid, CH(OH) (SO 3 H) 2 (B. 6, 1032) ; dichlormethane monosulphonic acid, dichlormethyl alcohol, known as acetic esters. Appendix. Carbon Monoxide, Isonitriles or Carbylamines, and Fulminic Acid. Carbon Monoxide, CO, a colorless, combustible gas, the product 236 ORGANIC CHEMISTRY. of the incomplete combustion of carbon, has already been discussed in the inorganic part of this book. The methods for its production and its transformations, which are of importance in organic chem- istry, will again be briefly reviewed. Carbon monoxide is obtained (i) from formic acid, (2) from oxalic acid and other acids, like lactic and citric, by the action of sulphuric acid. It is also made (3) from prussic acid, if, in preparing the latter from potassium ferrocyanide, K 4 Fe(CN) 6 . 3H 2 O, concentrated sulphuric acid be substituted for the more dilute acid, and in this manner the prussic acid be changed to formamide, and the latter immediately breaks down into ammonia and carbon monoxide. Formamide yields carbon monoxide upon the application of heat. Behavior. (i) Carbon monoxide and hydrogen exposed to the influ- ence of electric discharges yield methane (p. 80). Being an unsaturated compound, carbon monoxide unites (2) with oxygen, forming carbon dioxide; (3) with sulphur, yielding carbon oxysulphide ; and (4) with chlorine, to form carbon oxychloride or phosgene. It is rather re- markable that it also combines directly with certain metals. (5) With potassium it forms potassium carbon monoxide or potassium hexoxyben- zene (see this), C 6 O 6 K 6 ; (6) with nickel it yields nickel carbonyl, (CO) 4 Ni (Mono!, Quincke, and Langer, B. 23, R. 628). It forms alkali formates with the alkaline hydroxides (p. 225), and with (7) sodium methylate and sodium ethylate it yields sodium acetate and propionate. Carbon Monosulphide, CS, is not yet known (B. 28, R. 388). Isonitriles, Isocyanides, or Carbylamines are isomeric with the alky I cyanides or the acid nitriles, but are distinguished from these in that they have their alkyl group joined to nitrogen. The isonitriles were first prepared in 1866 by Gautier (A. 151, 239). He employed two methods. The first consisted in allowing alkyl iodides (i mol.) to act upon silver cyanide (p. 231) (2 mols.), while in the second method the addition products of silver cyanide and the alkyl isonitriles were decomposed by distillation with potassium cyanide: a. C 2 H 5 I -f 2AgCN = C 2 H 5 NC . AgCN -f Agl ib. C 2 H 3 NC . AgCN -f KCN = C 2 H 5 NC + AgCN . KCN. Shortly after A. W. Hofmann (A. 146, 107) found that isonitriles were produced by digesting chloroform and primary amines with alcoholic potash : 2. C 2 H 5 NH 2 + HCC1 3 + 3 KOH = C 2 H 5 NC + sKCl -f 3. The isonitriles are produced, too, as by-products, in the prepara- tion of the nitriles from alkyl iodides or sulphates and potassium cyanide (p. 266). Properties. The carbylamines are colorless liquids which can be distilled, and possess an exceedingly disgusting odor. They are sparingly soluble in water, but readily soluble in alcohol and ether. Transpositions. (i) The isocyanides are characterized by their ready decompo- FORMIC ACID AND ITS DERIVATIVES. 237 sition by dilute acids into formic acid and primary amines. This reaction proceeds readily by the action of dilute acids, or by heating with water to 180 C 2 H 5 . NC + 2H 2 = C 2 H 5 . NH 2 + CH 2 O 2 . Nitriles, on the other hand, by the absorption of water, pass into the ammonium salts of carboxylic acids : C 2 H 5 CN -f 2H 2 = C a H 5 COONH 4 . It is, therefore, concluded that in the nitriles the alkyl group is in union with carbon, while in the isonitriles it is linked to nitrogen. Three formulas have been suggested for the isonitriles : III II III IV V IV I. C 2 H 5 N=C II. C 2 H 5 N=C= III. C 2 H 5 N=C. Nef, who has studied several aromatic isonitriles exhaustively, gives formula I the preference (A. 270, 267). (2) The fatty acids convert isonitriles into alkylized fatty acid amides. (3) The isonitriles, like prussic acid (p. 228), form crystalline derivatives with HC1 ; probably these are the hydrochlorides of alkyl formimide chlorides, 2CH 3 . NC . 3HC1 = [CH 3 N = CHC1] 2 HC1, which water decomposes into formic acid and amine bases. (4) Mercuric oxide changes the isonitriles into isocyanic ethers, C 2 H 3 N = CO, with the separation of mercury, just as CO, by ab- sorption of oxygen, becomes CO 2 . Methyl Isocyanide, Methyl Carbylamine, hoacetonitrile, CH 3 NC, boils at 59. Ethyl Isocyanide, Ethyl Carbylamine, C 2 H 5 NC, boiling at 79, when heated at from 230 to 250, rearranges itself to propionitrile. It combines with chlorine to yield ethylisocyan chloride or ethylimidocarbonyl chloride, a derivative of carbonic acid ; with H. r S it forms thioformethylimide (p. 232), and with chloracetyl it produces ethylimidopyruvyl chloride, a derivative of pyroracemic acid (A. 280, 291). Fulminic Acid, Carbyloxime, C N. OH, is, according to Nef (A. 280, 303; B. 27, 2817), the oxime corresponding to carbon monoxide, and possesses the properties and characteristics of a strong acid. The fulminates have the same, percentage composition as the salts of cyanic acid : one of the first examples of isomeric compounds (Liebig, 1823). Free fulminic acid is but slightly known. Its odor is very similar to that of prussic acid, and the acid itself is not any less poisonous than that acid. The acid is formed when the fulminates are decomposed by strong acids. It combines quite readily with the latter, e.g., it yields formylchloridoxime with hydrochloric acid (p. 233), but this new body breaks down very easily with the formation of fulminic acid. The deportment of the fulminates toward hydro- chloric acid affords some insight into the constitution of fulminic acid itself. First, hydrochloric acid simply adds itself and salts of formyl- chloridoxime arise, from which, by the absorption of water, formic acid and hydroxylamine are formed : N . OAg C=NOAg -f HC1 = X C1 -f HC1 = HC -f AgCl C1 X C1 ,N.OH -f 2lI 2 O = H . CO 2 H -f NH 2 . OH . HC1. 23& ORGANIC CHEMISTRY. Mercury fulminate is the most important of the salts. It is applied, technically, as filling material in gun-caps. Mercury Fulminate, (C = N . O) 2 Hg -j- ^H,O (B. 18, R. 148), is formed (i) by heating a mixture of alcohol, nitric acid, and mercuric nitrate (B. 9, 787; 19, 993, 1370) ; (2) upon adding a solu- tion of sodium nitromethane to a solution of mercuric chloride : x ONa 2CH 2 =N/ + HgCl 2 = (C=N . 0) 2 Hg + 2 H 2 O + 2NaCl. There is always produced at the same time a yellow basic salt, := NO J 2 Hg, which is the sole product in pouring a solution of mercuric chloride into a solution of sodium nitromethane. Fulminating mercury crystallizes in shining, white needles, which are tolerably soluble in hot water. It explodes violently on percussion and also when acted upon by concentrated sulphuric acid. Con- centrated hydrochloric acid evolves CO 2 , and yields hydroxylamine hydrochloride and formic acid, a procedure well adapted for the preparation of hydroxylamine (B. 19, 993). Chlorine gas decomposes mercury fulminate into mercuric chloride, cyanogen chloride, and CC1 3 . NO 2 . Ammonia converts it into urea and guanidine (see acetyl isocyanate). Silver fulminate, C = NO Ag, is prepared after the manner of the mercury salt, and is even more explosive than the latter. Potassium chloride precipitates from hot solutions of silver fulminate one atom of silver as chloride and the double salt, C 2 AgKN 2 O 2 , crystallizes from the solution. Nitric acid precipitates from this salt acid silver fulminate, C 2 AgHN 2 O 2 , a white, insoluble precipitate. On boiling mer- cury fulminate with water and copper or zinc, metallic mercury is precipitated and copper and zinc fulminates (C 2 CuN 2 O 2 and C 2 ZnN 2 O 2 ) are produced. Sodium amalgam changes it to sodium fulminate, C = NONa. In the formation of salts and double salts fulminic acid conducts itself much like hydrocyanic acid. This is readily understood if prussic acid -be regarded as hydrogen isocyanide, C NH. Sodium ferrocyanide corresponds to sodium ferrofulminate, (C = NO) 6 FeNa 4 -)- i8H 2 O, which is produced by bringing together a solution of sodium fulminate and ferrous sulphate (A. 280, 335). It consists of yellow needles. Dibromnitroacetonitrile wDibromglyoximeperoxide^^^^ or 9 Br 2 NO 2 (?), melting at 50, is produced when bromine acts upon mercury fulminate. This body, when heated with hydrochloric acid, passes into BrH, NH 3 , NH 2 OH and oxalic acid. Aniline probably converts the dibromide into the dioxime of the oxanilide,- C 6 H 5 NHC=NOH C 6 H,NHC^NOH ' .OH Fulminuric Acid, Nitrocyanacetamide, C 3 N 3 O 3 H 3 = CN . CH(NO 2 )C<' , is a derivative of tartronic acid. Its alkali salts are obtained by boiling mercuric ful- minate with potassium chloride or ammonium chloride and water. The sodium salt is converted by a mixture of sulphuric and nitric acids, into trinitroacetonitrile. To obtain the free acid, decompose the lead salt with hydrogen sulphide. It deflagrates at 145. Especially characteristic is the Cuprammonium salt, C 3 N 3 O 3 H 3 (CuNH 3 ). It consists of glistening dark-blue prisms. (Compare Cyanuric acid.) ACETIC ACID AND ITS HOMOLOGUES. 239 Ethyl iodide converts the silver salt at 8o-9O into the Ethyl Ester, C 3 II 2 N 3 CH 3 [CH 2 ], 3 C0 2 H -f CH 3 . CO 2 H Pentadecylmethylketone from Pentadecylic Acid Acetic Acid. Palmitic Acid (10) Decomposition of unsaturated acids by fusion with caustic potash : KOH CH 3 . CH : C(CH 3 )CO 2 K - > CH 3 . CO 2 K and CH 3 . CH 2 . CO 2 K Potassium Angelicate Potassium Potassium Propionate. Acetate (n) Decomposition of acetoacetic ester, as well as mono- and dial- kylic acetoacetic esters, by concentrated caustic potash : CH 3 . CO . CH 2 . CO 2 C 2 H 5 -f 2KOH = CH 3 . CO 2 K + CH 3 . CO 2 K -f- C 2 H 5 OH Acetoacetic Ester CH 3 . CO .CH(R)CO 2 C 2 H 5 + 2KOH = CH, . CO 2 K -f CH 2 (R)CO 2 K -f C 2 H 5 . OH CH 3 . CO . C(R) 2 C0 2 C 2 H 5 + 2KOH = CH 3 . CO 2 K -f- CH(R) 2 CO 2 K + C 2 H 5 . OH. (12) Decomposition of ketoxime carboxylic acids, after their rear- rangement into acid amides. This reaction is valuable in determining the constitution of the olefine carboxylic acids, from which the ketoxime carboxylic acids can be prepared. (Compare oleic acid, p. 285.) (13) Decomposition of dicarboxyhc acids, in which the two carboxyl groups are in union with the same carbon atom. On the application of heat, these sustain a loss of carbon dioxide : /-ITT .^V^V^o-il t, rf^TT (~*C\ TT I C*r\ CH 2 CH 2 RC0 2 H + CO 2 C ( R )'CH_C0 2 H (CH,)oC . CO 9 H 4--2C 174 175 0.9470(0) 0.9410 (21) PROPION1C ACID, BUTYRIC ACIDS, VALERIC ACIDS. 247 Propionic Acid, Methylacetic Acid [Propan-acid], CH 3 . CH 2 . CO 2 H, may be prepared by the methods in general use in making fatty acids ; (I) by the oxida- tion of normal propyl alcohol and propylaldehyde with chromic acid ; (2) by reduc- tion of acrylic acid (p. 280) and propargylic acid (p. 287) ; (3) by reduction of lactic actd, CH g . CH(OH).CO,H, and glyceric acid; (4) (synthetically) from ethyl alcohol through its conversion, by means of ethyl iodide, into ethyl cyanide or pro- pionitrile ; (5) from sodium ethylate and carbon monoxide; (6) from sodium ethide and carbon dioxide; (7) ( by decomposition} in the oxidation of methyl-ethyl, methyl- propyl and diethyl-ketone ; (8) by the action of alcoholic potash upon methyl aceto- acetic ester with the simultaneous production of ethyl methyl ketone ; (9) from methylmalonic acid or isosuccinic acid by the application of heat. Its formation from malate and lactate of calcium by fermentation is worthy of note (B. 12, 479; 17, 1190). Gottlieb first discovered propionic acid in 1847, when he fused cane sugar with caustic potash. Dumas gave the acid its name, derived from 7Ty)wroc, the first, rriuv, fat, because when treated in aqueous solution with calcium chloride it separated as an oil. It is the first acid which in its behavior approaches the higher fatty acids. The barium salt, (C 3 H 5 O 2 ) 2 Ba -(- H 2 O, crystallizes in rhombic prisms. The silver salt, C 3 H 5 O 2 Ag, dissolves sparingly in water. Butyric Acids, C 4 H 8 O 2 . Two isomeric acids are possible : (i) Normal Butyric Acid, Ethyl Acetic Add \Butan acid], butyric acid of fermentation, occurs free and also as the glycerol ester in the vegetable and animal kingdoms, especially in the butter of cows (to the amount of five per cent., together with considerable of the glycerides of palmitic, stearic, and oleic acids), in which Chevreul found it, in the course of his classic investigations upon the fats. It exists as hexyl ester in the oil of Heracleum giganteum, and as octyl ester in Pastinaca sativa. It has been observed free in the perspira- tion and in the fluids of the flesh. It may be obtained by the usual methods employed for the preparation of fatty acids, and is produced in the butyric fermentation of sugar, starch and lactic acid, and in the decay and oxidation of albuminoid bodies. Ordinarily the acid is obtained by the fermentation of sugar or starch, induced by the previous addition of decaying substances, e.g., cheese, in the presence of calcium or zinc carbonate, intended to neutralize the acids, which are formed. According to Fitz, the butyric fermentation of glycerol or starch is most advantageously evoked by the direct addition of schizomycetes, especially Bacillus subtilis and Bacillus boocopri- cus (B. 11,49, 53; 29, 2726). Butyric acid is a thick, rancid-smelling liquid, which solidifies when cooled. It boils at 163. It dissolves readily in water and alcohol, and may be thrown out of solution by salts. The ethyl ester boils at The calcium salt, (C 4 H 7 O 2 ) 2 Ca -f- H 2 O (A. 213, 67), yields brilliant leaflets, and is less soluble in hot than in cold water (in 3.5 parts at 15 j ; therefore the latter grows turbid on warming. (2) Isobutyric Acid, (CH :i ) 2 . CH . CO 2 H, dimethyl acetic acid [Methyl Propan-acid], is found free in carobs (Ceratonia siliqua), 248 ORGANIC CHEMISTRY. as octyl ester in the oil of Pastinaca sativa, and as ethyl ester in croton oil. It is prepared according to the general methods (p. 239), while concentrated nitric acid converts it into dinitropropane($. 158). Potassium permanganate oxidizes it to a-oxyisobutyric acid. Isobutyric acid bears great similarity to normal butyric acid, but is not miscible with water. The calcium salt, (C 4 H 7 O 2 ) 2 Ca -f- 5H 2 O, dissolves more readily in hot than in cold water. Valeric Acids, C 5 H 10 O 2 . There are four possible isomerides (compare table, p. 246) : (1) Normal Valeric Acid, n-Propylacetic Acid [Pentan-acid], CH 3 . (CH 2 ) 3 . - CO 2 H, is formed according to the usual methods (p. 239). Ordinary valeric acid, or baldrianic acid, occurs free, and as esters in the animal and vegetable kingdoms, chiefly in the small valerian root (Valeriana officinalis), and in the root of Angelica A r change lie a, from which it may be isolated by boiling with water or a soda solution. It is a mixture of isovaleric acid with the optically active methyl-ethyl acetic acid, and is therefore also active. A similar artificial mixture may be obtained by oxidizing the amyl alcohol of fermentation (p. 127) with a chromic acid solution. Valeric acid combines with water and yields an officinal hydrate, C 5 H 10 O 2 -f- H 2 O, soluble in 26.5 parts of water at 15. (2) Isovaleric Acid, Isopropyl Acetic Acid [3 Methylbutan- acid], (CH 3 ) 2 .CH.CH 2 . CO 2 H, may be synthetically obtained by some of the methods described on p. 240. It is an oily liquid with an odor resembling that of old cheese. Potassium permanganate oxidizes isovaleric acid to /3-oxyisovaleric acid, (CH 3 ) 2 . - C(OH) . CH 2 . CO 2 H. Concentrated nitric acid attacks, in addition, the CH group, forming methyloxysuccinic acid, fi-nitroisovalericacid, (CH 3 ) 2 . C(NO 2 ) . CH 2 CO 2 H, and fi-dinitropropane, (CH 3 ) 2 C(NO 2 ) 2 (B. 15, 2324). The isovaleratrs generally have a greasy touch. When thrown in small pieces upon water they have a rotary motion, dissolving at the same time. Barium salt, (C 5 H 9 O 2 ) 2 Ba. The calcium salt, (C 5 H 9 O 2 ) 2 Ca -f 3H 2 O, stable, readily soluble needles. The zinc salt, (C 5 H 9 O 2 ) 2 Zn -j- 2H 2 O, crystallizes in large, brilliant leaflets ; when the solution is boiled a basic salt separates. (3) Methyl-ethyl Acetic Acid, [2-Methyl-butan-acid], ^> CH.CO 2 H, contains an asymmetric carbon atom, and, like its corresponding alcohol (p. 127), may exist in two optically active and one optically inactive modification. The optically inactive form has been synthesized, and has also been resolved by means of its brucine salts into its optically active components. The 1-salt dissolves with difficulty. The specific rotatory power of the optically active methyl -ethyl acetic acids is : [a] 5 = 17-85 (B. 29, 52). Calcium salt, (C ? H 9 O 2 ) 2 Ca -f 5H 2 O. An optically active methyl-ethyl acetic acid is present in the naturally occurring valeric acid, together with isopropyl-acetic acid, but in consequence of the slight crystallizing power of its salts it has not been isolated from the isopropyl-acetic acid (A. 204, 159), and is obtained by the oxidation of the amyl alcohol of fermenta- tion (see above). HIGHER FATTY ACIDS. 249 (4) Trimethyl Acetic Acid, (CH 3 ) 3 C . CO 2 H (Pivalic acid], [Dimethylpropan- acid], is formed from tertiary butyl iodide, (CH 3 ) 3 CI (p. 140), by means of the cyanide, also by the oxidation of pinacoline (p. 216). The acid is soluble in 40 parts H 2 O at 20, and has an odor resembling that of acetic acid. Barium salt, (C 5 H 9 O 2 ) 2 Ba -f- 5H 2 O. Calcium salt, (C 5 H 9 O 2 ^Ca -f 5H 2 O. HIGHER FATTY ACIDS. The subjoined table contains the melting and boiling points of the higher fatty acids, beginning with those containing six carbon atoms. The boiling points enclosed in parentheses were determined under 100 mm. pressure : Name. Formula. M. P. B. P. n-Hexoic Acid, n-Caproic Acid, CH 3 .(CH 2 ) 4 C0 2 H + 8 205 Isobutyl Acetic Acid (B. 27, R. 191), (CH 3 ) 2 CH[CH 2 ] 2 C0 2 H 198 Sec. Butyl Acetic Acid (B. 26, R- 93*)> / /~i T_T \ /"^T T \ /"~* TT /~' 1 F T /^"/^V TT I v^olT- ) ' V^JTAo )\^il. V_, 11 . v^vJrt 11 174 Diethylacetic Acid, 190 Methyl-n-propyl Acetic Acid, . \ 2 CtL, pTT /-Q TT Methyl-isopropyl Acetic Acid, /c 3 H 7 > - 2 I 9 I Dimethyl-ethyl Acetic Acid, . c H ^CC0 2 H -14 I8 7 n-Heptoic Acid, Oenanthylic 2 5 Acid, CH 3 (CH 2 ) 5 CO 2 H 10.5 22^ Methyl-n-butyl Acetic Acid, . 210 Ethyl-n-propyl Acetic Acid, . C 2 H 5 > CH CO 2 H 209 3 ru Methyl-diethyl Acetic Acid, . CH 3 \C.C0 2 H 208 n-Octoic Acid, Caprylic Acid, . n-Xonoic Acid, Pelargonic Acid, CH 3 ( 5 CH 2 ) 6 C0 2 H CH 3 (CH 2 ) 7 C0 2 H 16.5 12.5 237 254 n-Capric Acid, CH 3 (CH 2 ) 8 C0 2 H 3'-4 270 n-Undecylic Acid, CH 3 (CH 2 ) 9 C0 2 H 28.5 (212.5) n -Laurie Acid, CH 3 (CH 2 ) 10 C0 2 H 43-5 (225) n-Tridecylic Acid, CH 3 (CH 2 ) n C0 2 H 40-5 (236 ) n-Myristic Acid, . . .... CH 3 (CH 2 ) 12 C0 2 H 53-8 (220.5) n-Pentadecatoic Acid (B. 27, R. 191), CH 3 (CH 2 ) 13 C0 2 H 5 l0 (260) n-Palmitic Acid, CH^fCHJ^COoH 62 ( 27 8 c) n-Margaric Acid, ... ... 3v ^"^ 2/14 2 CH 3 (CH 2 ) ]5 CO 2 H CQ Q V /O / n-Stearic Acid, I)i-n-octyl Acetic Acid, . . . CH 3 (CH 2 ) ]6 C0 2 H [CH 3 (CH 2 ) 7 ] 2 CHC0 2 H J7' 7 6 9 .2 38.5 (29?) n-Arachidic Acid, C 20 H 40 O 2 20 40 2 yrO Behenic Acid o -o Cerotic Acid, r R o 2 78 Melissic Acid, . . . C'HO! / 00 ^30 * ' 60^2 y 250 ORGANIC CHEMISTRY. The normal fatty acids in the preceding list, having an even number of carbon atoms, occur almost exclusively in the natural oils and fats, which are chiefly glycerides of these acids. Palmitic and stearic acids possess great technical importance. Caproic Acid, n-Hexylic Acid, CH 3 (CH 2 ) 4 CO 2 H, occurs in the form of its glycerol ester in cow's butter, goat butter, and in cocoanut oil. It is produced, together with butyric acid, in the butyric fermentation. Oenanthylic Acid, n-Hepty lie Acid, CH 3 (CH 2 ) 5 CO 2 H, can easily be obtained as an oxidation product of oenanthol($. 196). Caprylic Acid, u-OctoicAcid, CH 3 (CH 2 ) 6 CO 2 H, occurs as glycerol ester in goat butter and in many fats and oils ; also in the fusel-oil of wine. Pelargonic Acid, u-nonoic acid, CH 3 (CH 2 ) 7 CO 2 H, is present in the leaves of Pelargonium roseum, and is prepared by the oxidation of oleic acid and oil of rue (methyl -n-nonyl ketone, p. 216). It may also be obtained by the fusion of undecyl- enic acid with potassium hydroxide. Capric Acid, n-Decylic Acid, CH 3 (CH 2 ) 8 CO 2 H, is present in butter, goat butter, in cocoanut oil and in many fats, and as amyl ester in fusel oil. It is the first normal acid that is solid at the ordinary temperature. n-Undecylic Acid, CH 3 (CH 2 ) 9 CO 2 H, is obtained by reduction of undecylenic acid from castor oil. Laurie Acid, \\-Dodecylic Acid, CH 3 (CH 2 ) 10 CO 2 H, occurs as glycerol- ester in the fruit of Laurus nobilis, and in pichurium beans. It is found as cetyl ester in spermaceti. Myristic Acid, \\-Tetradecylic Acid, CH 3 . (CH 2 ) 12 CO 2 H, occurs in muscat butter (from Myristica moschata], in spermaceti and oil of cocoanut, in myristin (B. 18, 201 1 ; 19, 1433), in earth-nuts (B. 22, 1743), in ox-bile (B. 25, 1829), and as free acid, as well as methyl ester, in iris root (B. 26, 2677). Palmitic Acid, n-Hcxadecylic Acid, CH 3 (CH 2 ) 14 CO 2 H. The glycerol ester of this acid and that of stearic acid and oleic acid con- stitute the principal ingredients of solid animal fats. Palmitic acid occurs in rather large quantities, partly uncombined, in palm oil. Spermaceti is the cetyl-ester of the acid, while the myricyl ester is the chief constituent of beeswax. The acid is most advantageously ob- tained from olive oil, which consists almost exclusively of the glycerides of palmitic and oleic acids (see latter) ; also, from Japanese beeswax, a glyceride of palmitic acid (B. 21, 2265). The acid is artificially made by heating cetyl alcohol with soda lime to 270 ; also by fusing together oleic acid and potassium hydroxide. Margaric Acid, C 17 H 34 O 2 , does not apparently exist naturally in the fats. It is made in an artificial way by boiling cetyl cyanide with caustic potash. Stearic Acid, n-Octodecylic Acid, CH 3 (CH 2 ) 16 CO 2 H, is associated with palmitic and oleic acids as a mixed glyceride in solid animal fats the tallows. Its name is derived from aria =. tallow. Arachidic Acid, CH 3 (CH 2 ) 18 CO 2 H, occurs in earth-nut oil (from Arachis hypogaa}. It has been obtained synthetically from aceto-acetic ester and octodecyl iodide (from stearyl aldehyde) (B. 17, R. 570). For products derived from arachidic acid, see B. 29, R. 852. Theobromic Acid, derived from cacao butter, melts at 72, and appears to be identical with arachidic acid. SYNTHESIS AND DECOMPOSITION OF THE FAT1Y ACIDS. 251 Behenic Acid, C., 2 H 44 O 2 , is found in the oil obtained from Moringa oleifera, and has been prepared by the reduction of iodobehenic acid from erucic acid (B. 27, R- 577)- Cerotic Acid, G^H M Q, (B. 29, R. 995), occurs, together with melissic acid, in a free condition in beeswax, and may be extracted from this on boiling with alcohol. As ceryl ester, it constitutes the chief ingredient of Chinese -wax. Its name is derived from cera = wax. Melissic Acid, C^H^O^ is formed from myricyl alcohol (p. 130) when the latter is heated with soda-lime. It is a waxy substance, melting at 88, and is really, as it appears, a mixture of two acids. The acids mentioned in the table, but not described here, have been prepared by the usual synthetic methods. Some of them will be encountered later in the form of oxidation or reduction products of complicated, complex aliphatic derivatives. SYNTHESIS AND DECOMPOSITION OF THE FATTY ACIDS. The synthetic methods presented for the production of the fatty acids are not equally well adapted for this purpose. Thus, methods 5, 6, and 7 (p. 240) are re- stricted to the 'synthesis of the simplest members of the series. Reactions more satisfactory than these, and especially fit for the synthesis of the higher monodialkylic acetic acids, are based on the deportment of acetoacetic ester and malonic ester (methods 10 and II). However, from the very nature of affairs, trialkylic acetic acids can not be synthesized in this way. It is only the fourth method of formation the synthesis of an acid cyanide from the iodide of an alcohol containing an atom less of carbon than the cyanide and the acid derived from it that will lead to the synthesis of not only mono- and di-, but also of trialkylic acetic acids. The nitriles of the latter e.g. , of trimethyl acetic acid, dimethylethyl acetic acid, and diethylmethvl acetic acid have been obtained from the iodides of the corresponding tertiary alco- hols. The nitrile synthesis renders the formation of acids from alcohols possible, and inasmuch as acids can be reduced to aldehydes and alcohols by the fourth trans- position method (p. 243), the synthesis of these two classes of bodies is made possible. Lieben, Rossi, and Janecek (A. 187, 126), beginning with methyl alcohol, system- atically prepared the normal acids and corresponding alcohols up to oenanthic acid, according to the following scheme : CH 3 . OH > CH 3 I > CH 3 . CN ^ CH 3 . CO 2 H > CH 3 . CHO Methyl Alcohol Methyl Iodide Methyl Cyanide Acetic Acid Acetaldehyde OH CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 Ethyl Alcohol Ethyl Iodide Ethyl Cyanide Propionic Acid Propionic Aldehyde. Three reactions come into consideration in the breaking-down or decomposition of the normal fatty acids : (1) The method of formation 8 (p. 243) of cnrboxylic acids: oxidation of mixed methyl-n-alkyl ketones, in which the CO-group continues in combination with the methyl group. (2) The transformation 10 (p. 243) of acid amides by bromine and caustic potash. (3) The action of iodine upon the silver salts. The first of these three reactions F. Krafift employed in a systematic way for the breaking-down of stearic acid into normal fatty acids of known constitution, from which it was concluded that stearic acid and the lower homologues derived from it possessed normal constitution. Upon distilling barium stearate, (C,-H 3 -CO 2 ) 2 Ba, and barium acetate, (CH 3 . CO. 2 ) 2 Ba, heptadecylmethyl ketone, C 7 HCOCH 8 , results. When this is oxidized it breaks down into margaric acid, C 16 H 33 CO 2 H, and acetic acid. Barium margarate and barium acetate yield hexadecylmethyl ketone, 252 ORGANIC CHEMISTRY. C 16 H 33 . CO. CH 3 , and this, by oxidation, passes into palmitic acid, C 15 H 31 CO 2 H, and acetic acid, etc. : C 17 H 35 CO(X , (CH 3 C0 2 ) 2 Ba Cr0 3 C 17 H^COO> Ba Barium Stearate Barium Margarate Palmitic Acid. A. W. Hofmann (B. 19, 1433) discovered the second method. It will be treated more fully in connection with the acid amides and nitriles (p. 266). The presenta- tion of its course by diagram will only be given here. When the acid amides are treated with bromine and caustic potash they split off CO in the form of CO 2 and pass into the next lower primary amines, which by further treatment with the same reagents become the nitrile of a carboxylic acid containing an atom less of carbon, and its amide is still capable of a like transformation. By this method the higher, more easily obtained normal fatty acids can be transposed into lower acids : C ]3 H 27 CONH 2 - > Ci 3 H 27 NH 2 - > C 12 H 25 CN - ** C 12 H 25 CONH 2 Myristamide Tridecylamine Tridecylnitrile Tridecylamide. (4) Action of iodine upon silver salts : silver acetate yields, in addition to CO 2 , the acetic methyl ester; silver capronate yields CO 2 and caproic amyl ester (B. 25, R. 581; 26, R. 237): 2CH 3 CO 2 Ag -f I 2 = CH 3 CO 2 CH 3 -f CO 2 + 2AgI. TECHNICAL APPLICATION OF THE FATS AND OILS. Animal fats, especially sheep-tallow and beef-tallow, the nature of which was made clear by the classic researches of Chevreul in the begin- ning of this century, consist mainly of a mixture of glycerol esters of palmitic, stearic, and oleic acids, which are commonly called palmitin, stearin, and olein. They have been used in the preparation of arti- ficial butter (margarine), in the manufacture of stearin candles, soaps, and plasters from the acid residues present in them, and for the isola- tion of glycerol, which is used in part as such and in part in the form of nitroglycerin. Palm fat, cocoanut oil, and olive oil are also used as raw material. The so-called stearin of candles consists of a mixture of stearic and palmitic acids. For its preparation, beef-tallow and suet, both solid fats, are saponified with calcium hydroxide or sulphuric acid, or with superheated steam. The acids which separate are distilled with super- heated steam. The yellow, semi-solid distillate, a mixture of stearic, palmitic, and oleic acids, is freed from the liquid oleic acid by pressing it between warm plates. The residual, solid mass is then fused to- gether with some wax or paraffin, to prevent crystallization occurring when the mass is cold, and molded into candles. When the fats are saponified by potassium or sodium hydroxide, salts of the fatty acids soaps are produced, e.g., sodium palmitate, according to the equation : DERIVATIVES OF THE ACIDS. 253 CH 2 . CO(CH 2 ) U . CH 3 CH 2 . OH CHO . CO(CH 2 ) U . CH 3 -}- 3 NaOH = CH . OH + 3CH 3 (CH 2 ) u CO 2 Na. CH 2 . CO(CH 2 ) U . CH 3 CH 2 . OH Palmitin Glycerol + Sod. Palmitate. The sodium salts are solids and hard, while those with potassium are soft. Salt water will convert potash soaps into sodium soaps. In small quantities of water the salts of the alkalies dissolve com- pletely, but with an excess of water they suffer decomposition, some alkali and fatty acid being liberated. The action of soap depends on this fact (B. 29, 1328). The remaining metallic salts of the fatty acids are sparingly soluble or insoluble in water, but generally dissolve in alcohol. The lead salts, formed directly by boiling fats with litharge and water, constitute the so-called lead plaster. The natural fats almost invariably contain several fatty acids (frequently, too, oleic acid). To separate them, the acids are set free from their alkali salts by means of hydrochloric acid and then fractionally crystallized from alcohol. The higher, less soluble acids separate out first. The separation is more complete if the acids be fractionally precipitated. The free acids are dissolved in alcohol, saturated with ammonium hydroxide, and an alcoholic solution of magnesium acetate added. The magnesium salt of the higher acid will separate out first ; this is then filtered off and the solution again precipitated with magnesium acetate. The acids obtained from the several fractions are subjected anew to the same treatment, until, by further frac- tionation, the melting point of the acid remains constant an indication of purity. The melting point of a mixture of two fatty acids is usually lower than the melting points of both acids (the same is the case with alloys of the metals). Lanoline, or wool fat, is used in medicine. DERIVATIVES OF THE ACIDS, i. ESTERS OF THE FATTY ACIDS. The esters of organic acids resemble those of the mineral acids in all respects (p. 136), and are prepared by analogous methods. Methods of Formation. (i) By direct action of acids and alcohols, whereby water is formed at the same time : C 2 H 5 . OH -f C 2 H 3 . OH = C 2 H 5 . O . C 2 H 3 O + H 2 O. This transposition, as already stated, only takes place slowly (p. 137) ; heat hastens it, but it is never complete. If a mixture of like equivalents of alcohol and acid be employed, there will occur a time in the action when a condition of equilib- rium will prevail, when the ester formation will cease, and both acid and alcohol will be simultaneously present in the mixture. This ensues because the heat modulus of the reaction is very slight, and hence, in accordance with the principles of thermo- chemistry, and under slightly modified conditions, the reaction pursues a reverse course i. CH 3 G^ ^O . H \C1 We practically have from the above the following methods of preparation : (#) Distil the mixture of the acid or its salt with alcohol and sulphuric acid. (^) Or, when the esters volatilize with difficulty, the acid or its salt is dissolved in excess of alcohol (or the alcohol in the acid), and while applying heat, HC1 gas is conducted into the mixture (or H 2 SO 4 added), and the ester precipitated, by the addition of water, (c) The acid nitriles can be directly converted into esters by dissolving them in alcohol and heating them with dilute sulphuric acid (p. 267). In the case of many acids, a low percentage of al< o- holic hydrochloric acid has shown itself as particularly well adapted for esterification purposes (B. 28, 3201, 3215, 3252; compare esters of aromatic carboxylic acids). Berthelot has executed more extended investigations upon the ester formation. These are of great importance to chemical dynamics. Proceeding from the simple assumption that the quantities of alcohol and acid combining in a unit of time (speed of reaction) are proportional to the product of the reacting masses, whose quantity regularly diminishes, Berthelot has proposed a formula (Annalen chitn. phis., 1862) by which the speed of the reaction in every moment of time, and its extent, can be calculated, van't Hoff has deduced a similar formula (B. 10, 669), which Guldberg- Waage and Thomsen pronounce available for all limited reactions (ibid., 10, 1023). For a tabulation of the various calculations relating to this matter, see B. 17, 2177 ; 19, 1700. Of late, Menschutkin has extended the investigations upon ester forma- tions to the several homologous series of acids and alcohols (A. 195, 334, and 197, 193 ; B. 15, 1445 and 1572 ; 21, R. 41). It has been found that the normal, primary alcohols (methyl alcohol excepted) possess the same speed of reaction. The excep- tion is more reactive than the others. The secondary alcohols are esterified more slowly, and in the case of the tertiary alcohols this process proceeds very sluggishly. Formic acid is more reactive than acetic, and the latter more so than the succeeding homologues, with which the speed of esterification diminishes as the molecule grows larger. In acids where a primary alkyl is in union with carboxyl, the initial velocity is the greatest, those with secondary alkyls are less, and the lowest initial velocity is observed with acids having a tertiary alkyl. The following are noteworthy methods of formation : (2) Rearrangement of the alkyl esters of mineral acids with salts of the organic acids : (a) By the action of the alkylogens (I) upon salts (Ag) of the acids : ^ C 2 H 5 I -f CRJO . OAg == S F 1?>O -f Agl. ESTERS OF THE FATTY ACIDS. 255 () By the dry distillation of a mixture of the alkali salts of the fatty acids and salts of alkyl sulphates : S0 *<0 .' K 2 " 5 + CH 3 OK = S 4 K * + CH I 3 b>- (3) By the action of acid chlorides (p. 257) or acid anhydrides (p. 25 7) on the alcohols or alcoholates : a. CHgt) . Cl + C 2 H 5 . OH = f >O + HC1 ^ 2 rl 5 b. C 2 H 5 OH + (CH 3 CO) 2 = CH 3 COOC 3 H 5 + CH 3 COOH. (4) Electrosyntheses of monocarboxylic esters (p. 240). Properties. Usually, the esters of fatty acids are volatile, neutral liquids, soluble in alcohol and ether, but generally insoluble in water. Many of them possess an agreeable fruity odor, are prepared in large quantities, a4id find extended application as artificial fruit essences. Nearly all fruit-odors may be made by mixing the different esters. The esters of the higher fatty acids occur in the natural varieties of wax. Consult B. 14, 1274; A. 218, 337 ; 220, 290, 319 ; 223, 247, upon the boiling points, the specific gravities and specific volumes of the fatty acid esters. Transformations. (i) When the esters are heated with water they sustain a partial decomposition into alcohol and acid. This decom- position (saponification) (p. 112) is more rapid and complete on heat ing with alkalies in alcoholic solution : C 2 H 3 . O . C 2 H 5 -f KOH = C 2 H 3 . OK + C 2 H 5 . OH. Consult A. 228, 257, and 232, 103; B. 20/1634, upon the velocity of saponifica- tion by various bases. (2) Ammonia changes the esters into amides (p. 262) : C 2 M 3 . O . C 2 H 5 -f NH 3 = C 2 H 3 . O . NH 2 -f C 2 H 5 . OH. (3) The haloid acids convert the esters into acids and haloid-esters (A. 211, 178) : C 2 H 3 . O . C 2 H 5 + HI = C 2 H 3 . OH + C 2 H 5 L (4) By the action of PC1 5 the extra-radical oxygen is replaced by chlorine, and both radicals are converted into halogen derivatives. Compare oxalic ester for the course of this reaction : C 2 H 3 . O . C 2 H 5 + PC1 5 = C 2 H 3 . Cl -f C 2 H 5 C1 + POC1.. (5) The esters, containing alcohol radicals with high molecular weight, break down, when heated or distilled under pressure, into fatty acids and olefines (p. 92). Esters of Acetic Acid. The Methyl Ester, Methyl Acetate, C 2 H 3 O 2 . CH 3 , occurs in crude wood-spirit, boils at 57-5, and has a specific gravity of 0.9577 at o. Wlu-n chlorine acts upon it the alcohol radical is first substituted : C 2 H 3 O 2 . CH 2 C1 boils at 150; C 2 H 3 O 2 . CHC1 2 boils at 148. The Ethyl Ester, Ethyl Acetate Acetic Ether C 2 H 3 O 2 . C 2 IT 5 , boils at 77. At o its sp. gr. equals 0.9238. It is technically prepared from acetic acid, alcohol, and sulphuric acid. It is the officinal . Ether aceticus. It is the starting-point for the 256 ORGANIC CHEMISTRY. production of acetoacetic ester, CH 8 . CO . CH 2 . CO 2 . C 2 H 5 , a factor in the formation of antipyrine. Chlorine produces substitution products of the alcohol radicals. The \\-propyl ester boils at 101. The isopropyl ester boils at 91. \\-Bntyl ester boils at 124. The isobutyl ester boils at 116, the secondary butyl ester at ill , and the tertiary at 96. The Amyl Ester boils at 148 ; n-propyl -methyl carbinol acetate, (CH 3 CH 2 CH 2 )- (CH 3 )CHO. CO . CH 3 , at 133, and isopropyl methyl carbinol acetate at 125. At 200 it splits up into amylene and acetic acid. Isobutyl carbinol acetate, the acetic ester of amyl alcohol of fermentation, boils at 140. A dilute alcoholic solution of it has the odor of pears, and is used as pear oil. Acetic-n-ffexyl Ester occurs in the oil of Heracleum giganteum. It boils at 169- 170 and possesses a fruit-like odor. Acetic-n. -octyl ester is also present in the oil of Heracletim giganteum. It boils at 207 and has the odor of oranges. The allyl-ester boils at 98-100. For higher acetic esters, see A. 233, 260. Orthoacetic Ester, CH 3 . C(O . C 2 H 5 ) 3 , boiling at 132, is produced on warming a-trichlorethane or methyl chloroform, CH 3 . CC1 3 (p. 103), with sodium ethylate in ethereal solution. Furthermore, the addition products of the aldehydes and acetic anhydride are the acetic esters (p. 191) of those glycols not capable of existing in a free condition. The aldehydes are probably the anhydrides of these bodies. Later, in the presentation of the polyhydric alcohols their acetic esters will always be mentioned, for by their saponification a clue can be obtained as to the number of hydroxyl groups present in the alcohol. Esters of Propionic Acid. The methyl ester boils at 79.5. The ethyl ester boils -at 98.8. The n-propyl ester boils at 122 ; the isobtttyl ester at 137 ; and the isoamyl ester at 160 ; the latter has an odor like that of pine-apples. (See A. 233, 2530 Esters of n-Butyric Acid. Methyl Ester boils at 102.3, and has an odor like that of rennet. The ethyl ester boils at 120.9, nas a pine-apple-like odor, and is employed in the manufacture of artificial rum. Its alcoholic solution is the artificial pine-apple oil. The n-propyl ester boils at 143; the isopropyl ester at 128. The isobutyl ester boils at 157. The isoamyl ester boils at 178, and its odor resembles that of pears. The n-hexyl ester, boiling at 205, and n - octyl ester, boiling at 244, are found in the oil obtained from various species of Heracleum (see above) and the octyl ester in Pastinaca sativa (A. 163, 193; 166, 80 ; 233, 272). Methyl Isobutyric Ester boils at 92.3. Ethyl Isobutyric Ester, C 4 H 7 O 2 . C 2 H 5 , boils at 110. n-Propyl Ester boils at 135 (A. 218, 334). Esters of the Valeric Acids. n- Valeric Ethyl sterbo\h at 144 (A. 233, 274). i- Valeric Ethyl Ester boils at 135. i- Valeric Isoamyl Ester boils at 194. Methyl-ethyl Acetic Ethyl Ester boils at 133.5 (A. 195, 120). Trimethyl Acetic Ethyl Ester boils at Il8 (A. 173, 372). Esters of the Hexoic Acids. n-H. -ethyl ester boils at 167. Isobutylacetic Ethyl Ester boils at 161. n-Heptoic Ethyl Ester boils at 187-188. n-Octoic Ethyl Ester boils at 207-208 (A. 233, 282). n-Nonoic Ethyl Ester boils at 227-228. n-Caproic Ethyl Ester boils with decomposition, at 275-290 ; it is the principal constituent of the fusel oil of wine. Laurie Ethyl Ester boils at 269. Myristic Ethyl Ester melts at 10-11, and boils at 295. Spermaceti and the Waxes. Some of the esters with high molecular weights occur already formed in spermaceti and the waxes. This fact has been noted in ACID HALOIDS. 257 connection with the corresponding alcohols and acids. The waxes are distinguished from the fats in that they consist of esters of mono- hydric alcohols with high molecular weight, whereas the fats are the esters of the trihydric alcohol, glycerol. Spermaceti belongs to the wax variety. Spermaceti (Cetaceum, Sperma Ceti*) occurs in the oil from pecu- liar cavities in the heads of whales (particularly Physeter macro- cephalus), and upon standing and cooling it separates as a white crys- talline mass, which can be purified by pressing and recrystallization from alcohol. It consists of Cetyl Palmitic Ester, C 16 H 31 O 2 .- C 16 H 33 , which crystallizes from hot alcohol in waxy, shining needles or leaflets, and melts at 49. It volatilizes undecomposed in a vacuum. Distilled under pressure, it yields hexadecylene &&& palmitic acid. When boiled with alcoholic caustic potash it becomes palmitic acid and cetyl alcohol. Ordinary beeswax is a mixture of cerotic acid, C 27 H 54 O 2 , with Myricyl Palmitic Ester, C I6 H 3] O 2 . C^H^. Boiling alcohol extracts the cerotic acid and the ester niyricin remains (A. 224, 225). Consult A. 235, 106, for other constituents of beeswax. Carnaiiba wax, from the leaves of the carnuba tree, melts at 83. It contains free ceryl alcohol and various acid esters (A. 223, 283). Chinese wax is Ceryl Cerotic Ester, C 27 H 53 O 2 . C 27 H 55 . Alcoholic potash de- composes it into cerotic acid and ceryl alcohol. a. ACID HALOIDS, OR HALOID ANHYDRIDES OF THE FATTY ACIDS. The haloid anhydrides of the acids (or acid haloids) are those derivatives which arise in the replacement of the hydroxyl of acids by halogens; they are the halogen compounds of the acid radicals. They have been termed haloid anhydrides, because they can be viewed as mixed anhydrides (p. 259) of the fatty acids and the haloid acids, corresponding to the method of formation (i) of the acid chlorides. Acid Chlorides. (i) From fatty acids and hydrochloric acid, by means of P 2 O 5 : P 2 5 CH 3 . COOH + HC1 - > CH 3 . COC1 -f H 2 O. (2) By the action of hydrochloric acid gas upon a mixture of an acid nitrile and a carboxylic acid or an anhydride at o. The hydro- chloride of the acid amide is produced at the same time (B. 29, R. 87): CH 3 CN -f CH 3 . COOH -f 2HC1 = CH 3 . CONH 2 . HC1 -f CH 3 . COC1. (3) By the action of chlorine upon aldehydes: CH 3 . COH -f C1 2 = CH 3 . COC1 + HC1. (4) A far more important method of formation consists in letting 22 258 ORGANIC CHEMISTRY. the phosphorus haloids act upon the acids or their salts just as the alkylogens are produced from the alcohols (p. 139) : CH 3 . COOH -f PCL = CH 3 . COC1 4- POCL -f HC1 }CH 3 . COOH + PC1 3 = 3 CH 3 . COC1 + PO 3 H S i 3 . COONa + POC1 3 ^ 2CH 3 . COC1 -f PO 3 Na + NaCl. (a) (b] 3 CH 3 .^, (e) 2CH 3 .COON Should there be an excess of the salt, the acid will also act upon it and acid anhydrides result (p. 259). The action, particularly upon the salts, is very violent. (5) Carbon oxychloride and thionyl chloride (see malonyl chloride) act upon the free acids and their salts the same as the chlorides of phosphorus. Acid chlorides and anhydrides are produced. This method has met with technical application (B. 17, 1285; 21, 1267): C 2 H 3 . OH -f COC1 2 = C a H 8 OCl + CO 2 + HC1. (6) Acid chlorides are also produced by the interaction of phosgene and zinc alkyls (p. 240). Historical. Liebig and Wohler obtained the first acid choride in 1832, when they treated benzaldehyde, C 6 H 5 COH, with chlorine. It was benzoyl chloride. C 6 H 5 - COC1, the chloride of the simplest aromatic acid benzoic acid. In 1846, Cahours discovered the method of producing aromatic acid chlorides by the action of phos- phorus pentachloride upon monocarboxylic acids. Acetyl chloride was first prepared in 1851 by Gerhardt (A. 87, 63) by treating sodium acetate with phosphorus oxy- chloride. Acid Bromides. (l) The phosphorus bromides act like the corresponding chlorides upon the fatty acids or their salts. A mixture of amorphous phosphorus and bromine may be employed as a substitute for the prepared bromide. (2) An interesting method for preparing the acid bromides consists in letting air act upon certain bromide derivatives of the alkylens, whereby oxygen will be absorbed. An intramolecular atomic rearrangement (p. 52) takes place (B. 13, 1980; 21,3356): ' O Unsym. Dibromethylene, CH 2 = CBr 2 > CH 2 Br . COBr, Bromacetyl Bromide. O Tribromethylene, CHBr = CBr 2 > CHBr 2 . COBr, Dibromacetyl Bromide. Acid Iodides. Phosphorus iodide does not convert the acids into iodides of the acid radicals ; this only occurs when the acid anhydrides are employed. They are also produced by the interaction of acid chlorides and calcium iodide. Acid Fluorides. Acetyl Fluoride is a gas with an odor resembling that of phos- gene. It is formed in the action of AgF or AsF, ; upon acetyl chloride. A better procedure consists in allowing acid chlorides to act u on anhydrous zinc fluoride. Propionyl Fluoride, CH 3 . CH 2 . COF, boils at 44. Properties and Transpositions. The acid haloids are sharp-smelling liquids, which fume in the air. They are heavier than water, sink in it, and at ordinary temperatures (i) decompose, forming acids and halogen hydrides. The more readily soluble the resulting acid is in water, the more energetic will the reaction be. The acid chlorides act similarly upon many other bodies. (2) They yield compound ethers, or esters, with the alcohols or alcoholates (p. 253). (3) With salts or acids they yield acid anhydrides (p. 259), and (4) with ammonia, the amides of the acids, etc. (5) Sodium amalgam, or better, sodium and oxalic acid (B. 2, 98), will convert the acid chlorides into aldehydes and alcohols (pp. 190 ACID ANHYDRIDES. 259 and 113)- (6) They yield ketones and tertiary alcohols when treated with the zinc alkyls (pp. 209 and 113). (7) By the action of silver cyanide they pass into the acid cyanides, which are described as the nitriles of the a-ketone carboxylic acids. (8) Di- and poly carboxylic acids, having the power of forming anhydrides, pass when treated with acid chlorides (especially acetyl chloride) into their anhydrides. Acetyl Chloride [Ethanoyl Chloride], CH 3 . CO. Cl, boils at 55. It is formed according to the general methods applied in the production of acid chlorides, and by carefully distilling a mixture of acetic acid (3 parts) and PC1 3 (2 parts). Or, heat POC1 3 (2 molecules) with acetic acid (3 molecules), as long as HC1 escapes, then distil (A. 175, 378). The acetyl chloride is purified by again distilling over a little dry sodium acetate. It is a colorless, pungent smelling liquid which has a specific gravity of 1.130 at o. Water decomposes it very energetic- ally. For its transformations, consult the preceding paragraphs. Acetyl chloride forms chlorinated acetic acids with chlorine. Com- pare acetyl acetone. Acetyl Bromide boils at 8l. Acetyl Iodide boils at 108. Propionyl Chloride, CH 3 . CH 2 . CO . Cl, boils at 80; the bromide, at 104, and the iodide at 127. Butyryl Chloride, C 4 H 7 O . Cl, boils at 101. Aluminium chloride changes it to triethylphloroglucin (B. 27, R. 57)- The \\.-bromide boils at 128; the n-iodide at 146148. Sodium amalgam converts it into normal butyl alcohol. Isobutyryl Chloride, (CH,^ . CH . CO . Cl, boils at 92; the bromide at 116-118. Isovaleryl Chloride, C 5 H 9 O.C1, boils at 113.5-114.5; the bromide at 143, and the iodide at 168 Tri methyl Acetic Chloride, (CH 3 ) 3 C . COC1, boils at 105-106. n- Caproyl Chloride, CH 3 (CH 2 ) 4 COC1, boils at 151-153. Diethylacetyl Chloride, (CLHACHCOCl, boils at 134-137. Dimethyl-ethyl acetic chloride, (CH 3 ) 2 (C 2 H 5 )C . COC1, boils at 132. Consult B. 17, 1378; 19, 2982; 23, 2384, for the chlorides of the higher fatty acids. 3. ACID ANHYDRIDES. The acid anhydrides are the oxides of the acid radicals. In those of the monobasic acids two acid radicals are united by an oxygen atom ; they are analogous to the oxides of the univalent alcohol radicals the ethers. The simple anhydrides, those containing two similar radicals, can as a general thing be distilled, while the mixed anhydrides, with two dissimilar radicals, decom- pose when thus treated, into two simple anhydrides : CT_IO C T~T O fTTO Hence they are not separated from the product of the reaction by distillation, but are dissolved out with ether. Methods of Formation. (id) The chlorides of the acid radi- 260 ORGANIC CHEMISTRY. cals are allowed to act on anhydrous salts viz., the alkali salts of the acids : C 2 H 3 O . OK -f C 2 H 3 O . Cl = 2 H 3 o> + KCL (ib] The anhydrides of the higher fatty acids can be produced further by the action of acetyl chloride on the latter (B. 10, 1881). (2) Phosphorus oxychloride (i molecule) acts upon the dry alkali salts of the acids (4 molecules). The acid chloride which appears in the beginning acts immediately upon the excess of salt : I Phase : 2C 2 H 3 O . OK -f POC1 3 = 2C 2 H 3 O . Cl -f PO 3 K -f KC1 II Phase : C 2 H 3 O . OK -f C 2 H 3 O. Cl = (C 2 H 3 O) 2 O -f- KC1. (3) Phosgene, COC1 2 , acts like POC1 3 . In this reaction acid chlorides are also produced (p. 258). (4) A direct conversion of the acid chlorides into the corresponding anhydrides may be effected by permitting the former to act upon anhydrous oxalic acid (A. 226, 14) : 2C 2 H 3 OC1 + C 2 4 H 2 = (C 2 H 3 0) 2 + 2HC1 + CO 2 + CO. Historical. Charles Gerhardt (1851) discovered the acid anhydrides. The im- portant bearing of this discovery upon the type theory has already been alluded to in the introduction. Properties and Deportment. The acid anhydrides are liquids or solids of neutral reaction, and are soluble in ether. Their boiling points are higher than those of the corresponding acids, (i) Water decomposes them into their constituent acids : (C 2 H 3 0) 2 + H 2 = 2C 2 H 3 . OH. (2) With alcohols they yield the esters: (C 2 H 3 0) 2 + C 2 H 5 . OH =: C2 0 + C 2 H 3 . OH. (3) Ammonia and primary and secondary amines convert them into amides and ammonium salts : (CH 3 CO) 2 + 2NH 3 = CH 3 . CONH 2 -f CH 3 . COONH 4 . (4) Heated with hydrochloric acid, hydrobromic and hydriodic acids, they decompose into an acid haloid and free acid : (C 2 H 3 O) 2 O + HC1 == C 2 H 3 O . Cl -f C 2 H 3 O . OH. (5) Chlorine splits them up into acid chlorides and chlorinated acidb : (C 2 H 3 0) 2 + C1 2 = C 2 H 3 . Cl -f Cl . CH 2 . COOH. (6) Sodium amalgam changes the anhydrides to aldehydes and primary alcohols. (7) Aldehydes and acid anhydrides combine to esters. THIO-ACIDS. 261 Acetic Anhydride [Ethan-acid Anhydride], (C 2 H 3 O) 2 O, is a mobile, pungent-smelling liquid boiling at 137. Its specific gravity equals 1.073 at - To prepare it, distil a mixture of anhydrous sodium acetate (3 parts) with phos- phorus oxychloride (l part) ; or, better, employ equal quantities of the salt and acetyl chloride. Propionic Anhydride, (C 3 H 5 O) 2 O, boils at 168. Butyric Anhydride boils at 191-193. hobntyric Anhydride boils at 181.5. n-Caproic Anhydride boils with decompo- sition at 241-243. CEnanthic Anhydride boils at 258 with partial decomposition. Pelargonic Anhydride melts at +5 wA. palmitic anhydride at 64. 4. ACID PEROXIDES. The peroxides of the acid radicals are produced on digesting the chlorides or anhydrides in ethereal solution with barium peroxide (Brodie, Pogg. Ann., 121, 382) or by the action of ice-cold chlorides upon hydrated sodium peroxide (B. 29, 1726) : 2C 2 H 3 O . Cl -j- BaO 2 = (C 2 H 3 O) 2 O 2 -f BaCl 2 . Acetyl Peroxide is a thick liquid, insoluble in water, but readily dissolved by alcohol and ether. It is a very unstable, strong, oxidizing agent, separating iodine from potassium iodide solutions and decolorizing a solution of indigo. Sun- light decomposes it, and when heated it explodes violently. With barium hydroxide it yields barium acetate and barium peroxide. 5. THIO-ACIDS. By the replacement of oxygen in a monocarboxylic acid by sulphur three cases are possible : 1. R/.CO. SH Thio-acids [Throlic Acids] 2. R/. CS .OH Thionic Acids, compare Thiamides 3. R'. CS . SH Dithionic Acids [Thionthiolic Acids]. Aliphatic acids of the first kind alone are known. The first thio-acid thiacetic acid, CH 3 . COSH, was obtained by Kekule (A. 90, 309) when phosphorus penta- sulphide acted upon acetic acid. It is advisable to mix the P 2 S 5 with half its weight of coarse pieces of glass : 5C 2 H 3 . OH + P 2 S 5 = 5C 2 H 3 . SH + P 2 O 5 . The thio-anhydrides arise in the same manner by the action of phosphorus sulphide upon the acid anhydrides. The thio-acids are produced by the action of acid chlorides upon potassium sulphydrate. The disagreeably-smelling thio-acids correspond to the thio-alcohols or mercaptans (p. 149), their sulphanliydrides to the acid anhydrides and the simple sulphides, and their disulphides to the peroxides and alkyl disulphides : CH 3 . CH 2 SH CH 3 . COSH CH 3 . CO 2 H Ethyl Mercaptan Thiacetic Acid Acetic Acid (CH 3 . CH^S (CH 3 . CO) 2 S (CH 3 CO) 2 Ethyl Sulphide Thiacetic Anhydride Acetic Anhydride (CH 3 . CH 2 ) 2 S 2 (CH 3 . CO) 2 S 2 (CH 3 . CO) 2 O 2 Ethyl Disulphide Acetyl Bisulphide Acetyl Peroxide. 262 ORGANIC CHEMISTRY. The esters are obtained when the alkylogens react with the salts of the thio-acids, and by letting the acid chlorides act upon the mercaptans or mercaptides. They also appear in the decomposition of alkylic isothio-acetanilides with dilute hydrochloric acid : /S.C 2 H 5 CH 3 . C^ -f H 2 O = CH 3 . CO . S . C 2 H 5 + NH 2 . C 6 H 5 . Ethyl-isothio-acetanilide Thio-acetic Ester Aniline. Concentrated caustic potash decomposes the esters into fatty acids and mercaptans. Thiacetic Acid [Ethaniol-add], CH 3 COSH, is a colorless liquid, boiling at 93. Its specific gravity at 10 is 1.074. Its odor resembles those of acetic acid and hydrogen sulphide. It dissolves with difficulty in water, but readily in alcohol and in ether. This acid has been recommended as a very convenient substitute for hydrogen sulphide in analytical operations (B. 28, R. 616). The lead salt, (C 2 H 3 - O . S) 2 Pb, crystallizes in minute needles, and readily decomposes with the formation of lead sulphide. The ethyl ester, C 2 H 3 O . S . C 2 H 5 , boils at 115. Acetyl Sulphide, (C 2 H 3 O) 2 S, is a heavy, yellow oil, insoluble in water. It boils at 157. Water gradually decomposes it into acetic and thiacetic acids (B. 24, 3548, 4251). Acetyl Bisulphide, (C 2 H 3 O) 2 S 2 , is formed when acetyl chloride acts upon potassium disulphide, or iodine upon the salts of the thio-acid. 6. ACID AMIDES. These correspond to the amines of the alcohol radicals. The hydro- gen of ammonia can be replaced by acid radicals, forming primary, secondary and tertiary acid amides : CH 3 . CO . NH 2 (CH 3 . CO) 2 NH (CH 3 . CO) 3 N Acetamide (primary) Diacetamide (secondary) Triacetamide (tertiary). Recently the idea has been expressed that the constitution of the primary acid OH amides might be represented by the formula R 7 . C<^ (compare benzamide), from which the imido-ethers (p. 269) are derived. The hydrogen of primary and secondary amines, like that of am- monia, can be replaced by acid residues, giving rise to mixed amides. General Methods of Formation. (i) The dry distillation of the ammonium salts of the acids of this series. A more abundant yield is obtained by merely heating the ammonium salts to about 230 (B. 15, 979), (Ktindig, 1858). (This method was first applied (1830) by Dumas to ammonium oxalate with the production of oxamide). This procedure is adapted to the preparation of volatile amides : C 2 H 3 . O . NH, = C 2 H 3 . NH 2 + H 2 O. Ammonium Acetate Acetamide. A mixture of the sodium salts and ammonium chloride may be substituted for the ammonium salts. Consult B. 17, 848, upon the velocity and limit of the amide production. (2) The action of ammonia, primary and secondary amines upon ACID AMIDES. 263 the esters (by this procedure Liebig, in 1834, obtained oxamide from oxalic ester) : CH 3 CO . O . C 2 H 5 + NH 3 = CH 3 CO . NH 2 + C 2 H 5 . OH Acetamide CH 3 CO . O . C 2 H 5 + C 2 H 5 . NH 2 = C 8 H S O > NH + C 2 H 5 . OH. Ethyl 5 Acetamide. This is a reaction that frequently takes place in the cold ; it is best, however, to apply heat to the alcoholic solution. It is one of the so-called reversible reactions, inasmuch as the action of alcohols upon acid amides again produces esters and ammonia (B. 22, 24). (3) By the action (#) of acid haloids, (U} of add anhydrides upon ammonia, primary and secondary alkylamines. (This method Liebig and Wohler first used in 1832 to prepare benzamide from benzoyl chloride.) : (30) CH 3 . COC1 + 2NH 3 = CH 3 . CONH 2 -f NH 4 C1 Acetamide CH 3 . COC1 + 2NH 2 C 2 H 5 = CH 3 . CONH . C 2 H 5 + N(C 2 H 5 )HC1 Ethyl Acetamide CH 3 . COC1 + 2NH(C 2 H 5 ) 2 = CH 3 . CON(C 2 H 5 ) 2 -f N(C 2 H 5 ) 2 H 2 C1. Diethyl Acetamide. This method is especially well adapted for obtaining the amides of the higher fatty acids (B. 15, 1728) : (3*) (CH 3 . CO) 2 O + 2NH 3 = CH 3 . CONH 2 -f CH 3 . CO 2 NH 4 (CH 3 . CO) 2 O -f 2NH 2 C,H 5 = CH 3 . CONHC 2 H 5 -f CH 3 . CO 2 NH 3 C 2 H 5 . (4) The addition of one molecule of water to the nitriles of the acids: CH 3 . CN -f H 2 (180) = CH 3 . CO . NH 2 . Acetonitrile Acetamide. This addition of water frequently occurs in the cold by the action of concentrated hydrochloric acid, or by mixing the nitrile with glacial acetic acid and concentrated sulphuric acid (B. 10, 1061). Hydrogen peroxide in alkaline solution also converts the nitriles, with liberation of oxygen, into amides (B. 18, 355). For the action of hydrochloric acid upon a mixture of nitrile and fatty acid see (2) formation of acid chlorides. (5) The distillation of the fatty acids with potassium sulphocyanide : 2C 2 H 3 O . OH + CN . SK = C 2 H 3 O . NH 2 -f C 2 H 3 O . OK + COS. Simply heating the mixture is more practical (B. 16, 2291 ; 15, 978). In making acetamide glacial acetic acid and ammonium sulphocyanide are heated together for several days. In this reaction the aromatic acids yield nitriles. (6) By the interaction of fatty acids and carbylamines (p. 236) : 2CH 3 . COOH + C : N . CH 3 = H . CONHCH 3 + (CH 3 CO) 2 O. Methyl Formamide. (7) By the action of the fatty acids upon isocyanic acid esters (see these) : CH 3 . COOH -f CON . C 2 H 5 = CH 3 . CONHC 2 H 5 -f CO 2 . 264 ORGANIC CHEMISTRY. Secondary and tertiary amides are obtained (l) by heating primary acid amides (B. 23, 2394), the alkyl cyanides or nitriles with acids, or acid anhydrides, to 200: CH 3 . CONH 2 + (CH 3 CO) 2 O = (CH 3 . CO) 2 NH -f CH 3 . COOH CH 3 CN + CH 3 . COOH = (CH 3 CO) 2 NH Diacetamide CH 3 . CN -f (CH 3 CO) 2 O = (CH 3 CO) 3 N. Triacetamide. (2) The secondary amides can also be prepared by heating primary amides with dry hydrogen chloride : 2C 2 H 3 O . NH 2 + HC1 = (C 2 H 3 O) 2 NH -f NH 4 C1. Diacetamide. (3) Mixed amides are further produced by the action of esters of ordinary isocyanic acid upon acid anhydrides : CO : N . C 2 H 5 + (C 2 H 3 0) 2 = > Ethyl Diacetamide. Properties and Behavior. The amides of the fatty acids are usually solid, crystalline bodies, soluble in both alcohol and ether. The lower members are also soluble in water, and can be distilled without decomposition. As they contain the basic amido-group they are able to unite directly with acids, forming salt-like derivatives (V. g., C 2 H 3 O . NH 2 . NO 3 H and (CH 3 CO . NH 2 ) 2 . HC1), but these are not very stable, because the basic character of the amido-group is strongly neutralized by the acid radical. Furthermore, the acid radical imparts to the NH 2 -group the power of exchanging a hydrogen atom with metals, e.g., mercury or sodium (B. 23, 3037), forming metallic derivatives, e.g., (CH 3 . CO . NH) 2 . Hg-^-mercury acetamide, analo- gous to the isocyanates (from isocyanic acid, CO : NH), and the salts of the imides of dibasic acids. The union of the amido-group with the acid radicals (the group CO) is very feeble in comparison with its union with the alkyls in the amines (p. 159). The amides, therefore, readily absorb water and pass into ammonium salts, or acids and ammonia, (i) Heating with water effects this, although it is more easily accomplished by boiling with alkalies or acids. This is a reaction which is not infre- quently termed saponification (p. 239). CH 3 . CO . NH 2 + H 2 = CH 3 . CO . OH + NH 3 . Acid amides, saponifying with difficulty, are dissolved in sulphuric acid, and to this cold solution sodium nitrite is added (B. 28, 2783). (2) Nitrous acid decomposes the primary amides similarly to the primary amines (p. 166) : C 2 H 3 . NH 2 + N0 2 H = C 2 H 3 . OH + N 2 + H 2 O. (3) Bromine in alkaline solution changes the primary amides to bromamides (B. 15, 407 and 752) : C 2 H 3 . NH 2 + Br 2 = C 2 H 3 O . NHBr -f HBr, ACID HYDRAZIDES. 265 which then form amines (p. 163). (4) On heating with phosphorus pentoxide, or with the chloride, they part with one molecule of water and become nitriles (cyanides of the alcohol radicals) : CH 8 . CO . NH 2 = CH 3 . CN -f H 2 O. In this action a replacement of an oxygen atom by two chlorine atoms takes place; the resulting chlorides, like CH 3 . CC1 2 . NH 2 , then lose, upon further heating, two molecules of C1H with the formation of nitriles. Formamide, H . CONH 2 . See p. 227. Acetamide [Ethanamide], CH 3 CO . NH 2 , crystallizes in long needles, melts at 82-83, and boils at 222 undecomposed. It dis- solves with ease in water and alcohol. In explaining the methods of producing the amides, and in illustrating their deportment, acetamide was presented as the example. Dumas, Leblanc, and Malaguti first prepared it in 1847, by allowing ammonia to act upon acetic ester. Acetmethylamide, CH 3 . CONHCH 3 , melts at 28 and boils at 206 ; acetdim ethyl- ami Je, CH 3 .CO. N(CH 3 ) 2 , boils at 165.5; acetethylamid'e boils at 205; acet- diethylamide boils at 185-186. Mefhylene diacetamide, CH 2 (NHCOCH 3 ) 2 , melts at 196 and boils at 288 (B. 25, 310). Chloralacetamide, CC1 3 CH(OH)NHCOCH 3 , melts at 117 (B. 10, 168). Acetamide and butylchloral yield two isomeric com- pounds melting at 158 and 170 respectivejy (B. 25, 1690). Diacetamide, (C 2 H 3 O) 2 NH, is readily soluble in water, fuses at 77, and boils at 222.5-223.5. (Preparation, p. 264.) Methyidiacetamide, (CH 3 CO) 2 N . CH 3 , boils at 192. Ethyldiacetamide boils at 185-192. Triacetamide, (C 2 H 3 O) 3 N, melts at 78-79. (Preparation, p. 264.) Acetchloramide, CH 3 CONHC1, melts at 110. Acetbromamide ', CH 3 CONHBr-|- H 2 O, forms large plates, and melts in an anhy- drous condition at 108 (B. 23, 2395). Higher homologous primary Acid Amides : Propionamide melts at 75 and boils at 210. n-Butyramide fuses at 115 and boils at 216. Isobutyramide fuses at 128 and boils at 216-220. n-Valeramide fuses at 114-116. Trimethylacetamide melts at 153-154 and boils at 212; n-Capronamide melts at 100 and boils at 225; Methyl-n-propylacetamide melts at 95; Methyl-isopropylacetamide melts at 129; Isobutylacetamide melts at 120; Diethylacetamide melts at 105 and boils at 230-235 ; (Enanthamide melts at 95 and boils at 250-258; n-Caprylamide melts at 105-106; Pelargonamide melts at 92-93 ; n-Caprinamide melts at 98. Lauramide fuses at 102 and boils at 199-200 (12.5 mm.); Tridecylamide melts at 98.5 ; Myristamide, at 102, and boils at 217 (12 mm.) ; Palmitamide, at 106, and boils at 235-236 (12 mm.); Stearamide melts at 108.5-109 and boils at 250-251 (12 mm.) (B. 15, 977, 1729 ; 19, 1433 ; 24, 2781 ; 26, 2840). 7. ACID HYDRAZIDES. Acethvdrazide, CH 3 CO . NH . NH 2 , melts at 62. Acetbenzalhydrazine, CH 3 .- O ) . NH . N : CH . C 6 H 5 , melts at 134 (B. 28, R. 242). 23 266 ORGANIC CHEMISTRY. 8. THE FATTY ACID NITRILES OR ALKYL CYANIDES. These are compounds in which one carbon atom, combined with an alkyl group R'.CEE, a residue present in every fatty acid, replaces the three hydrogen atoms of ammonia, e. -.,CH 3 C = N, acetonitrile. It is true that in the nitrile bases (tertiary amines and amides) the nitrogen atom is also joined with three valences to carbon, but three alkyl residues are in union with three different carbon atoms. The acid nitriles are also called alkyl cyanides, because they can be viewed as alkyl ethers of hydrogen cyanide, H . C = N. Being intermediate steps in the synthesis of the fatty acids from the alcohols, these nitriles merit especial consideration. The following general methods answer for their preparation : (i) Nucleus-synthesis from the alcohols : (a) by heating the alkyl- ogens with potassium cyanide in alcoholic solution to 100; (^) by distillation of a potassium alkyl sulphate with potassium cyanide (hence the name alkyl cyanides} : (la) C 2 H 5 I -f CNK = C 2 H 5 . CN -f KI (16 ) SO 4 <^ H 4- CNK = C 2 H 5 . CN + K 2 SO 4 . Isocyanides (p. 235) form in slight amount in the first reaction. For their re- moval shake the distillate with aqueous hydrochloric acid until the unpleasant odor of the isocyanides has disappeared, then neutralize with soda and dry the nitriles with calcium chloride. (2) By heating alkyl isocyanides or alkyl carbylamines (p. 237) : 2 S CH 3 . CH 2 . NC - -- fe- CH 3 CH 2 CN. (3) The dry distillation of ammonium salts of the acids with P. 2 O 5 , or some other dehydrating agent : CH 3 . CO . O . NH 4 2H 2 O = CH 3 . CN. Ammonium Acetate Acetonitrile. This method of production explains why these cyanides are termed acid nitriles. The corresponding acid amide is an intermediate product. (4) By the removal of water from the amides of the acids when these are heated with P 2 O 5 , P 2 S 5 or phosphoric chloride (see amid- chlorides, p. 268) : CH 3 . CO . NH 2 4- PC1 5 == CH 3 . CN + POC1 3 4 2HC1 5CH 3 . CO . NH 2 -f P 2 S 5 = 5CH 3 . CN -f P 2 O 5 + sH 2 S. (5) Primary amines, containing more than five carbon atoms, are converted, by caustic potash and bromine, into nitriles : C 7 H 15 CH 2 NH 2 4- 2Br 2 -f 2KOH = C 7 H ]5 CH 2 NBr 2 4- 2KBr + 2lI 2 O C 7 H 15 CH 2 NBr 2 4. 2KOH = C 7 H 15 CN + 2KBr 4- 2lI 2 O. THE FATTY ACID NITRILES OR ALKYL CYANIDES. 267 As the primary amines can be obtained from acid amides containing a carbon atom more, these reactions will serve for the breaking- down of the fatty acids (p. 243). (6) Nitriles result when aldoximes are heated with acetic anhydride or with thionyl chloride (B. 28, R. 227): CH 3 CH = N. OH 4- (CH 3 CO) 2 O = CH 3 C=N + 2CH 3 . COOH. (7) On the application of heat to cyanacetic acid and alkylized cyanacetic acid nitriles result : CN . CH 2 . CO 2 H = CN . CH 3 4- CO 2 . The nitriles occur already formed in bone-oils. Historical. Pelouze (1834) discovered propionitrile on distilling barium ethyl sulphate with potassium cyanide (A. 10, 249). Dumas (1847) obtained acetonitrile by distilling ammonium acetate alone, or with P 2 O 5 ; the same occurred with the latter reagent and acetamide (p. 265). Dumas, Malaguti and Leblanc (A. 64, 334) on the one hand, and Frankland and Kolbe (A. 65, 269, 288, 299) on the other, demonstrated (1847) th e conversion of the nitriles into their corresponding acids by means of caustic potash or dilute acids, and thus showed what importance the acid nitriles possessed for synthetic organic chemistry. Properties and Behavior. The nitriles are liquids, usually insoluble in water, possessing an ethereal odor, and distilling without decompo- sition. Their reactions are based upon the easy disturbance of the triple union between nitrogen and carbon. They are mostly additive reac- tions. Acid nitriles may be viewed as unsaturated compounds, in the same sense as aldehydes and ketones (pp. 38, 187). Their neutral char- acter distinguishes them from prussic acid, the nitrile of formic acid. In respect to this transposition of their C=N-group they resemble the nitrile of formic acid. (1) Nascent hydrogen converts them into primary amines (Mendius). This reduc- tion is most easily accomplished by means of metallic sodium and absolute alcohol (B. 22, 812). (2) The nitriles can unite with the halogen hydrides, forming amide and imide haloids. (3) Under the influence of concentrated sulphuric acid they take up water and become acid amides (p. 262). When heated to 100 with water the acid amides first formed absorb a second molecule of water and change to the fatty acid and ammonia. The nitriles are more readily saponified by heating them with alkalies or dilute acids (hydrochloric or sulphuric acid). Esters are produced when the acids, in a solution of absolute alcohol, act upon the nitriles. (4) The nitriles form thiamides with H 2 S (p. 269). (5) They combine with alcohols and HC1 to imido-ethers (p. 269). 268 ORGANIC CHEMISTRY. (6) With monobasic acids and acid anhydrides they yield secondary and tertiary amides (p. 264). (7) The nitriles become amidines with ammonia and the amines (p. 270). (8) Hydroxylamine unites with them to form amidoximes (p. 271). Metallic sodium induces in them peculiar polymerizations. In ethereal solution, dimolecular nitriles result : imides of fi-ketonic nitriles. All these reactions depend upon the additive power of the nitriles, the triple carbon-nitrogen union being broken. If, however, sodium acts upon the pure nitriles at a temperature of 150 the products are trimolecular nitriles , so-called cyanethines (see \hese] t pyrimidine derivatives: 2CH 3 CN - > CH 3 . C(NH) . CH 2 . CN Imido-acetic Nitrile N C(CH,)=:N 3CHXN - > CH 3 . C CH =C . NH 2 . Cyanethine (see this). Acetonitrile, Methyl Cyanide [Ethan-nitrile], CH 3 . CN, melts at 41 C., boils at 81.6, has a specific gravity of 0.789 (15), and is a liquid with an agreeable odor. It is usually prepared by distilling acetamide with P 2 O 5 . Consult the general description of acid nitriles for its methods of formation, its history and its transposition reac- tions. It may, however, be mentioned here that acetonitrile can be produced from prussic acid and diazomethane (B. 28, 857). Higher Homologous Nitriles. Propionitrile, Ethyl Cyanide [Propan- nitrile], C 2 H 5 . CN, boils at 98. Its specific gravity equa's 0.801 (o). n-Butyronitrile boils at 118.5, an d has the odor of bitter-almond oil. Iso- butyronitrile boils at 107. n-Valeronitrile boils at 140.4; isopropylacetonitrile boils at 129; methyl-ethylacetonitrile boils at 125 ; trimethylacetonitrile melts at 15-16 and boils at 105-106. Isobutylacetonitrile boils at 154; diethyl- acetonitrile boils at 144-146; dimethyl-ethylacetonitrile boils at 128-130; n cenanthylnitrile boils at 175-178 ; n-caprilonitrile boils at 1 98-200 ; pelar- gonitrile boils at 214-216; methyl-n-hexylacetonitrile boils at 206; lauro- nitrile boils at 198 (100 mm.); tridecylonitrile boils at 275; myristonitrile melts at 19 and boils at 226.5 ( Io mm.) ; palmitonitrile melts at 29 and boils at 251.5 (100 mm.) ; cetyl cyanide melts at 53 ; stearonitrile melts at 41 and boils at 274.5 (100 mm.). Several classes of compounds bear genetic relations to the acid amides and nitriles, but these will be considered after the nitriles. 9. AMID-CHLORIDES and 10. IMID-CHLORIDES (Wallach, A. 184, i). The amid-chlorides are the first unstable products arising in the action of PC1 5 upon acid amides. They part with hydrochloric acid and become imid- chlorides, which by a further separation of hydrochloric acid yield nitriles : _HC1 >CH 3 C~N C1 Acetamide (Acetamid-chloride) (Acetimid-chloride) Acetonitrile. THIAMIDES. 269 The addition of HC1 to the nitriles produces the imid-chlorides. Hydrogen bromide and hydrogen iodide add themselves more readily than hydrogen chloride to nitriles (B. 25,2541): ,NH NH NH , 3 - X Br \Br Acetimid-bromide Acetamid-bromide Acetamid-iodide. If a hydrogen atom of the amid-group be replaced by an alcohol radical, the imid- chlorides will be more stable. On heating, however, they lose hydrochloric acid in part and pass into chlorinated bases. (i) Water changes the imid-chlorides back into add amides. The chlorine atom of these bodies is as reactive as the chlorine atom of the acid chlorides. (2) Am- monia and the primary and secondary amines change the imid-chlorides to amidines (see below). (3) Hydrogen sulphide converts the imid-chlorides into thiamides. ii. IMIDO-ETHERS* (Pinner, B. 16, 353, 1654; 17, 184, 2002). The imido-ethers may be regarded as the esters of the imido-acids, R'. a formula which has, in recent times, been proposed for the acid amides (p. 262 ); compare also the thiamides. The hydrochlorides of the Imido-ethers are produced by the action of HC1 upon an ethereal mixture of a nitrile with an alcohol (in molecular quantities) : .NH . HC1 CH 3 . CN + C 2 H 5 . OH -f HC1 = CH 3 . C^ \0 . C 2 TI 5 . Acetimido-ether. Formimido-ether (p. 232), Acetimido-ethyl Ether, when liberated from its HCl-salt by means of NaOH, is a peculiar-smelling liquid. Ammonia and the amines convert the imido-ethers into amidines, 12. THIAMIDES. As in the case of the acid amides (p. 262), so here with the thiamides two formulas are possible : V NH 2 .NH 2 /NH ,NH R'.CC R'.C< and R'.Cf R'.CT . ^O ^S X)H X SH The thiamides are formed (i) by letting phosphorus sulphide act upon the acid amides (p. 262) ; (2) by the addition of H 2 S to the nitriles: CH 3 . CN -f H 2 S = CH 3 . CS . NH 2 . Acetonitnle Thiacetamide. (1) The thiamides are readily broken up into fatty acids, SH 2 , NH 3 and amines. (2) They yield thiazole derivatives with chloracetic ester, chloracetone, and similar bodies. (3) Ammonia converts them into amidines. (4) The action of hydroxylamine results in the production of oxamidines. Thiacetamide melts at 108 (A. 192, 46; B. 11,340). Thiopropionamide melts at 42-43 (A. 259, 229). * The Imido-ethers and their Derivatives, A. Pinner, 1892. 270 ORGANIC CHEMISTRY. ,NH 13. AMIDINES, R.C< (A. 184, 121 ; 192,46). X NH 2 The amidines, containing an amid- and imid-group, whose hydrogen atoms are replaceable by alkyls, may be considered derivatives of the acid amides, in which the carbonyl oxygen is replaced by the imid-group : CH 3 . CONH 2 CH 3 C(NH )NH 2 . Acetamide Acetamidine. They are produced : (1) From the imid-chlorides and thiamides, by the action of ammonia or amines. (2) From the nitriles by heating them with ammonium chloride. (3) From the amides of the acids when treated with HC1 (B. 15, 208) : NH (4) From the imido-ethers (p. 269) when acted upon with ammonia and amines (B. 16, 1647; 17, 179). The amidines are mono-acid bases. In a free condition they are quite unstable. The action of various reagents on them induces water absorption, the imid-group splits off, and acids or amides of the acids are regenerated. /3-Ketonic esters convert them m\.o pyrimidines , -e. g., acetamidine hydrochloride and aceto-acetic ester yield dimethyl-ethoxypyrimidine, melting at 192 (compare polym. acetonitrile, p. 268) : ,NH COCH 3 ^~ C ^ ~ CH 3 CH 3 C^ -f . = CH 3 C^ ^CH -f 2H 2 O. X NH 2 CH 2 . CO . OC 2 H. X N=C/ __ OC 2 H 5 Formamidine (p. 232). Acetamidine (Acediamine), Ethenylamidine , CH 3 C(NH 2 )NH. Its hydrochloric acid salt melts at 163. The acetamidine, separated by alkalies, reacts strongly alkaline and readily breaks up into NH 3 and acetic acid. ,N.OH 14. HYDROXAMIC ACIDS, R . C^ X OH These are produced when free hydroxylamine, or its hydrochloride, is allowed to act upon acid amides, esters and acid chlorides. They contain the isonitroso group in the place of the carbonyl oxygen (B. 22, 2854) : /N. OH CH 3 . CO . NH 2 -f NII 2 . OH = CH 3 . CH 2 O, melts at 59. It dissolves very easily in water and alcohol, but not in ether. ,N.OH 15. NITROLIC ACIDS, R . C^ (p. 157). X N0 2 As these bodies are genetically related to the mononitro-paraffins, they have already been discussed immediately after them. HALOGEN SUBSTITUTION PRODUCTS OF THE FATTY ACIDS. 271 ,N . OH 16. AMIDOXIMES or OXAMIDINES, R . C^ X NH 2 These compounds may be regarded as amidines, in which an H atom of the amid- or imid-group has been replaced by hydroxyl. They are formed : by the action of hydroxylamine on the amidines (p. 270); by the addition of hydroxylamine to the nitriles (B. 17, 2746) : NH 2 CH 3 . CN -f NH 2 . OH = CH 3 . C^ Acetonitrile Ethenylamidoxime. and by the action of hydroxylamine upon thiamides (B. 19, 1668) : /NH 2 CH 3 . CS . NH 2 -f NH 2 OH = CH 3 . C^ -f H 2 S. The amidoximes are crystalline, very unstable compounds, which readily break down into hydroxylamine, and the acid amides or acids. Methenyl-amidoxime, Formamidoxime or Isuretine (p. 233). Ethenyl-amidoxime, CH 3 . C/ , melts at 135. Hexenyl-amidoxime melts at 48. Heptenyl-amidoxime melts at 48-49 (B. 25, R. 637). Laurin- amidoxime melts at 92-92.5. Myristin-amidoxime melts at 97. Palmitin- amidoxime melts at 101.5-102. Stearin-amidoxime melts at 106-106.5 (B. 26, 2844). When the aromatic derivatives are discussed we shall again meet with bodies be- longing to the classes which have just been considered, viz., the imid-chlorides, imido- ethers, thiamides, amidines, hydroxamic acids and amidoximes. The aromatic primary amines, e.g., aniline and toluidine, are not only prepared techni- cally on a large scale, but they are more readily accessible than the primary, aliphatic bases, and are more easily handled because of their slighter volatility. Beginning with them, phenylated, etc. , derivatives of the aliphatic imid-chlorides have been prepared. On the other hand, benzoic acid and its homologues are excellent material for the study of the carboxyl derivatives of a monocarboxylic acid. This acid im- parts the power of crystallization to many of its compounds, and that, again, renders easy the work with them. Hence, the corresponding aromatic derivatives supple- ment the aliphatic imid-chlorides, etc. HALOGEN SUBSTITUTION PRODUCTS OF THE FATTY ACIDS. The reactions leading to the substituted fatty acids are partly the same as those employed in the formation of the halogen substitution products of the paraffins. (i) Direct substitution of the hydrogen of the hydrocarbon residue, joined to car- boxyl, by halogens. (a) Chlorine in sunlight, or with the addition of water and iodine, or sulphur (B. 25, R. 797), or phosphorus (B. 24, 2209). 272 ORGANIC CHEMISTRY. (b] Bromine in sunlight, or with the addition of water in a closed tube at a more elevated temperature, or with the addition of sulphur (B. 25, 3311), or phos- phorus (B. 24, 2209). (c} Iodine with iodic acid, or brom-fatty acids with potassium iodide. The acid chlorides, bromides, or acid anhydrides are more readily substituted than the free acids. When chlorine or bromine, in the presence of phosphorus, acts upon the fatty acids (method of Hell-Volhard) , acid chlorides and bromides result ; these then are subjected to substitution. The final products are halogen-acid chlo- rides or halogen-acid bromides : 3CH 3 . CO 2 H + P -f 1 1 Br = 3CH 2 Br . COBr -f HPO 3 + 5HBr. However, substitution only takes place in a mono-alkyl or dialkyl-acetic acid at the a-carbon atom. Hence, trimethylacetic acid cannot be chlorinated or brominated. Consequently the deportment of a fatty acid towards chlorine or bromine and phos- phorus indicates whether or not a trialkyl-acetic acid is present (B. 24, 2209). (2) Addition of Haloid Acids to Unsaturated Monocarboxylic Acids. The halogen enters at a point as far as possible from the carboxyl group, e. g. : ( - --> CH 2 C1 . CH 2 . CO 2 H /3-Chlor- ) CH 2 : CH . CO 2 H 1 JUl^. CH 2 Br . CH 2 . CO 2 H /3-Brom- \ propionic acid. Acrylic Acid ( HI > cp^j ^ Q^ /Modo- J (3) Addition of Halogens to Unsaturated Monocarboxylic Acids. Whenever possible the chlorine is allowed to act in a CC1 4 solution. Bromine often adds itself without the help of a solvent, and also in the presence of water, CS 2 , glacial acetic acid and chloroform. (4) Action of the haloid acids (a) upon oxymonocarboxylic acids : CH 2 (OH)CH 2 C0 2 H -^> CH 2 C1 . CH 2 . CO 2 H -Pg TT TJ.. Lactic Acid : CH 3 CH (OH)CO 2 H > CH 3 CHBrCO 2 H a-Brompropionic Acid Glyceric Acid : CH 2 (OH)CH(OH)CO 2 H ^-^- CHJ . CH 2 . CO 2 H ^ Iod A P c^d P101 (4(5) Upon lactones, cyclic anhydrides of y- or d-oxyacids : f HBr ^ CH 2 Br . CH 2 . CH, . CO 2 H v^rij . Urljj J y-Brombutyric Acid CH 2 .CO^ ( HJ ^ CH 2 I.CH 2 .CH 2 .C0 2 H y-Iodobutyric Acid. (5) Action of the phosphorus haloids, particularly PC1 5 , upon oxymonocarboxylic acids. The product is the chloride of a chlorin- ated acid, which water transforms into the acid : CH 3 . CHOH . COOH -f 2PC1 5 = CH 3 . CHC1 . COC1 + 2POC1 3 -f 2HC1. Lactic Acid a-Chlorpropionyl Chloride. Furthermore, halogen fatty acids are obtained like the parent acids (6) by the oxidation of chlorinated alcohols or aldehydes (p. 197) with nitric acid, chromic acid, potassium permanganate or potassium chlorate (B. 18,3336): ojS-Dichlorhy- r . rwrl rH nM . rw r , rMri rn drin : CH 2 C1 . CHC1 . CH 2 OH - ,H 2 C1 . CHC1 . LO 2 rl propionic Acid Chloral: CC1 3 . CHO - > CC1 3 . COOH HALOGEN SUBSTITUTION PRODUCTS OF THE FATTY ACIDS. 273 (7) By the action of halogen hydrides upon diazo-fatty acid esters (see glyoxylic acid) : (8) When the halogens act upon diazo-fatty acid esters : CHN 2 CO 2 C 2 H 5 -f I 2 = CHI 2 CO 2 C 2 H 5 -f N 2 . Isomerism and Nomenclature. Structurally, isomeric halogen sub- stitution products of the fatty acids are first possible with propionic acid. To indicate the position of the halogen atoms, the carbon atom to which the carboxyl group is attached is marked a, while "the other carbon atoms are successively called /?, f, d, e, etc. The Jrwo monochlorpropionic acids are distinguished as a- and /3-chlorjropi- onic acids, while the three isomeric dichlorpropionic acids are the aa-, ftp- and a/3 dichlorpropionic acid, etc. Deportment. The introduction of substituting halogen atoms in- creases the acid character of the fatty acids. The halogen fatty acids, like the parent acids, yield, by analogous treatment, esters, chlorides, anhydrides, amides, nitrites, etc. Transpositions. (i) Nascent hydrogen causes the halogen substitu- tion products of the fatty acids to revert to the parent acids retro- gressive substitution. The transpositions of the monohaloid fatty acids, which bear the same relation to the alcohol acids or oxyacids as the alkylogens sustain to the alcohols, are especially important. In both classes the halogen atoms enter the reaction under similar conditions. (2) Boiling water, caustic alkali, or an alkaline carbonate solution generally brings about an exchange of hydroxyl for the halogen atom. However, in monohalogen products, the position of the halogen atom, with refer- ence to carboxyl, will materially affect the course of the reaction: a-halogen acids yield a-oxyacids, /3-haloid acids split off the haloid acid and become unsaturated acids ; y-halogen acids, on the contrary, yield y-oxyacids, which readily yield lactones (B. 219, 322) : TT f*\ CH 2 C1.COOH ! ^ -^ CH 2 (OH)C0 2 H CH 2 C1 . CH 2 . COOH CH 2 C1 . CH 2 . CH 2 . COOH - > CH 2 O . CH 2 . CH 2 CO. (3) Ammonia converts the halogen fatty acids into amido-acids. Nucleus- synthetic Reactions. (4) Potassium cyanide produces cyan- fatty acids half-nitrile fatty-acids, which hydrochloric acid changes to dibasic acids. They will be considered after the latter : KCN .C0 2 H 2H.O.HC1 ru ,C0 2 H ,H 2 C1.CO 2 H _. ^ CH 2 < CN 2 - _^ CH 2 first prepared by Dumas (1839) when he allowed chlorine to act in the sunlight upon acetic acid (A. 32, 101). Without essentially changing the chemical character, three hydrogen atoms of the acetic acid were replaced by chlorine a fact upon which Dumas then erected the type theory (p. 35). Kolbe (1845) made the acid by the oxidation of chloral with concentrated nitric acid (A. 54, 183), and demonstrated how it could be prepared synthetically from its elements : do Heat CC1 2 cio, 2H.,0 COOH C 2S _ _-_ _^cci- -> , The carbon disulphide resulting from carbon and sulphur is converted by the chlorine into carbon tetrachloride, which on the application of heat becomes per- chlorethylene, CC1 2 = CC1 2 (p. 105), and it, in turn, by the action of chlorine and water, aided by sunlight, yields trichloracetic acid. This was the first synthesis of HALOGEN SUBSTITUTION PRODUCTS OF THE FATTY ACIDS. 275 acetic acid, for Melsens had previously shown that potassium amalgam in aqueous solution reduced trichloracetic acid to acetic acid (p. 244). When digested with ammonia or alkalies, the acid breaks down into chloroform (p. 234) and a carbonate. The methyl ester boils at 152.5, and the ethyl ester at 164. They are obtained from the acid and alcohols (B. 29, 2210). Trichloracetyl chloride , Perchloracetaldehyde, boiling at Ii8, is formed when ozonized air acts upon perchlorethylene (B. 27, R. 509) ; compare synthesis of trichloracetic acid from CS 2 . The bromide boils at 143 ; the anhydride at 224; the amide melts at 141 and boils at 239; the nitrile boils at 83. Perchloracetic methyl ester, CC1 3 . CO 2 CC1 3 , melts at 34 and boils at 192 (A. 273, 61). Bromacetic Acids. Monobromacetic Acid, CH 2 Br.CO 2 H, melts at 50-51 and boils at 208 ; the ethyl ester boils at 159 ; the chloride boils at 134 ; the bro- mide, CH 2 Br. COBr, boils'at 150 (pp. 105, 258) ; the anhydride boils at 245; the amide melts at 91, and the nitrile boils at 148-150. Dibromacetic Acid, C 2 H 2 Br 2 O 2 , melts at 54-56, and boils at from 232-235. The ethyl ester boils at 192; the bromide, CHBr 2 .COBr (pp. 105, 258), boils at 194, and the amide melts at 156. Tribromacetic Acid, C 2 HBr 3 O 2 , melts at 135, and boils at 245, with decompo- sition. Its ethyl ester boils at 225; the bromide at 22O-225 ; the amide melts at 120-121; the nitrile boils at 170. It is a dark red liquid, which HC1 changes to the polymeric trinitrile, melting at 129 (B. 27, R. 730). lodoacetic Acids. Moniodoacetic Acid, C 2 H 3 IO 2 , melts at 82. Di-iodoacetic Acid, CHI 2 . CO 2 H, melts at Iio. Tri-iodoacetic Acid melts at 150. The last two compounds have been obtained from malonic acid and iodic acid (B. 26, R. 597)- Compare iodoform, page 235. Substitution Products of Propionic Acid. The a-monohaloid propionic acids contain an asymmetric carbon atom; hence their esters are known, for example, in an active form. They are prepared according to the methods 4^ and 5 (p. 272). The /3-monohalogen acids are derived from acrylic acid by method 3 (p. 272), and /3-iodopropionic acid from glyceric acid by method 40. a-Chlorpropionic Acid, CH 3 . CHC1 . CO 2 H , boils at 1 86. Its ethyl ester boils at 146; its chloride at 109-110; its amide at 80; its nitrile at 121-122. a-Brompropionic Acid melts at 24.5 and boils at 205. Its ethyl ester boils at 162; its bromide at 153 (A. 280, 247); its anhydride at .120 (5 mm.) (B. 27, 2949). a-Iodopropionic Acid is a thick oil. Dextrorotatory a-Chlor- and a-Brompropionic Esters have been prepared from sarcolactic acid (B. 28, 1293). /i-Chlorpropionic Acid, CH 2 C1 . CH 2 . CO 2 H, melts at 41.5 and boils at 203- 204. Its methyl ester boils at 156; its ethyl ester boils at 162; its chloride at 143-145. /3-Brompropionic Acid melts at 61.5; its ethyl ester boils at 69-70 (10 mm.); its bromide boils at 154-155. /3-Iodopropionic Acid melts at 82; the methyl ester boils at 188 ; the ethyl ester at 202; and the amide melts at 100 (B. 21, 24, 97). Dihalogen Propionic Acids. aa- Acids, from the chlorination and bromination of propionic acid (B. 18, 235) ; a/?-acids, by the addition of chlorine and bromine to acrylic acid, by the addition of a halogen hydride to rc-halogen acrylic acids, and by the oxidation of the corresponding alcohols (p. 272) ; /3/3-acids, by the addition of a halogen hydride to /3-halogen acrylic acids. aa-Dichlorpropionic Acid, CH 3 . CC1 2 . CO 2 H, boils at l85-i9O. The ethyl ester boils at I56-I57 ; its chloride, from pyroracemic acid and PC1 5 , boils at 105- 115, and the amide melts at Il6 (B. II, 388). The nitrile boils at 105 (B. g, 1593). The silver salt changes to CH 3 . CO . CO 2 H (pyroracemic acid), and ca-dichlor- propionic acid (see B. 18, 1227). aa-Dibrompropionic Acid melts at 6l and boils at 220. The ethyl ester boils at 190. a3 Dichlorpropionic Acid, CH 2 C1 . CHC1 . CO 2 H, melts at 50 and boils at 210. The ethyl ester boils at 184. 276 ORGANIC CHEMISTRY. a/3-Dibrompropionic Acid is capable of existing in two allotropic modifications, which can be readily converted one into the other. The one form melts at 51, the oilier, more stable, at 64. The acid boils at 227, with partial decomposition. The ethyl ester boils at 21 1-2I4. /3/3-Dibrompropionic Acid, from /3-bromacrylic acid and HBr, melts at 71 (B. 27, R. 257). Substitution Products of the Butyric Acids. a-Chlor-n-butyric Acid, CH 3 . CH 2 . CHC1 . CO 2 H, is a thick liquid. Its ethyl ester boils at 156-160. Its chloride^ boiling at 129-132, is obtained from butyryl chloride (A. 153, 241). a-Brombutyric Acid, from butyric acid, boils at 215. /3-Chlor-n-butyric Acid is obtained from allyl cyanide. /3-Brom-n-butyric Acid and /?-Iodo-n-butyric Acid (melting at 110) (B. 22, R. 74 1 ) have been obtained from crotonic acid. y-Chlor-n-butyric Acid, CH 2 C1 . CH 2 . CH 2 . CO 2 H, melts at 10. Trimethy- lene Chlorobromide, CH 2 C1 . CH 2 . CH 2 Br, and KCN, yield the y-chlorbutyric nitrile, boiling at 195-197 (B. 23, 1771). The acid is obtained from this, and when distilled at 200 it yields HC1 and butyro-lactone (see this). y-Brom- and y-Iodobutyric acids result from butyro-lactone (see this) by the action of HBr and HI ; the first melts at 33, -the second at 41 (B. 19, R. 165). a/3-Dichlorbutyric Acid, CH 3 . CHC1 . CHC1 . CO 2 H, melts at 63. a/3-Di- brombutyric Acid melts at 85. Both are obtained from crotonic acid. aa^-Trichlorbutyric Acid, C^HgClgOjj, appears in the oxidation of trichlorbutyr- aldehyde and by the action of chlorine upon chlorcrotonic acids (B. 28, 2661). aa/?-Tribrombutyric Acid melts at 105. The solutions of the sodium salts of both acids break down when warmed into CO 2 , sodium halide, and oa-dichlor- and aa-dibrompropylene (B. 28, 2663). a-Bromisobutyric Acid, (CH 3 ) 2 . CBr . CO 2 H, melts at 48 and boils at 198- 200. Its anhydride melts at 63 (B. 27, 2951). Halogen Substitution Products of Higher Fatty Acids. rt-Monobrom-acids of some of the higher fatty acids have been prepared by direct bromination, or by the action of bromine in the presence of phosphorus (B. 25, 486), Furthermore, such derivatives arise from the addition of halogen hydrides and halogens to unsaturated acids. The dibrom-addition-products of the unsaturated acids have been exhaustively studied. Water almost invariably sets the COOH free from the a/3-dibromides with the formation of brominated hydrocarbons, etc., whereas carbon is never split off from the /3y- and yd- derivatives, but the first products are brominated lactones, from which oxylactones and y-ketonic acids are simultaneously obtained (A. 268, 55). B. OLEIC ACIDS, OLEFINE MONOCARBOXYLIC ACIDS, C n H 2n - 1 C0 2 H. The acids of this series, bearing the name Oleic Acids, because oleic acid belongs to them, differ from the fatty acids by containing two atoms of hydrogen less than the latter. They also bear the same relation to them that the alcohols of the allyl series do to the normal alcohols. We can consider them derivatives of the alkylens, C n H 2n , produced by the replacement of one atom of hydrogen by the car- boxyl group. Some of the methods employed for the preparation of the unsatu- rated acids are similar to those used with the fatty acids. Others OLEIC ACIDS, OLEFINE MONOCARBOXYLIC ACIDS. 277 correspond to the methods' used with the defines, and others, again, are peculiar to this class o"f bodies. From compounds containing a like carbon content : (1 ) Like the fatty acids, they are produced by the oxidation of their corresponding alcohols and aldehydes; thus, allyl alcohol and its alde- hyde afford acrylic acid : CH 2 :CH.CH 2 .OH > CH 2 : CH . CHO >CH 2 : CH . CO 2 H. Allyl Alcohol Acrolei'n Acrylic Acid. (2) The action of alcoholic potash (p. 272) upon the monohalogen derivatives of the fatty acids : CH 3 . CH 2 . CHC1 . C0 2 H and CH 3 . CHC1 . CH 2 . CO 2 H yield CH 3 . CH : CH . CO 2 H a-Chlorbutyric Acid /3-Chlorbutyric Acid Crotonic Acid. The /3-derivatives are especially reactive, sometimes parting with halogen hydrides on boiling with water (p. 272), whereas the y-halogen acids yield oxy-acids and lactones. (3) Similarly, the a/3-derivatives of the acids (p. 274) readily lose two halogen atoms, (a) either by the action of nascent hydrogen CH 2 Br . CHBr . CO 2 H + 2H = CIT 2 : CH . CO 2 H + 2HBr, a/J-Dibrompropionic Acid Acrylic Acid. or (i>] even more readily when heated with a solution of potassium iodide, in which instance the primary di-iodo-compounds part with iodine (p. 131): CH 2 I . CHI . CO 2 H = CH 2 : CH . CO 2 H + T 2 . (4) The removal of water (in the same manner in which the alky- lens C n H 2n are formed from the alcohols) from the oxy-fatty acids (the acids belonging to the lactic series) : CH 3 . CH(OII) . C0 2 H and CH 2 (OH) . CH 2 . CO 2 H yield CH 2 : CH . CO 2 H. a-Oxypropionic Acid /3-Oxypropionic Acid Acrylic Acid. Here again the /3-derivatives are most inclined to alteration, losing water when heated. The removal of water from a-derivatives is best accomplished by acting on the esters with PO 3 . The esters of the unsaturated acids are formed first, and can be saponified by means of alkalies. (5) From the amido-fatty acids by the splitting off of the amido-group after the previous introduction of the methyl group. (6) By the addition of hydrogen to acetylene carbonic acids : Tetrolic Acid, CH 3 .C : C . CO 2 H + 2H=rCH 3 . CH : CH . CO 2 H, Crotonic Acid. Nucleus-synthetic Methods. (7) Some may be prepared synthetically from the halogen derivatives, C n H^^X, aided by the cyanides (see p. 240) ; thus allyl iodide yields allyl cyanide and crotonic acid, and the point of double union is changed : CH 2 = CHCH 2 T - ^ CH 3 CH = CHCN - > CH 3 CH = CHCO 2 H. The replacement of the halogen by CN in the compounds C n H 2n +]X is conditioned by the structure of the latter. Although allyl iodide, CH 2 : CH . CH 2 I, yields a cyanide, ethylene chloride, CH 2 : CHC1, and /3-chlorpropylene, CH 3 . CC1 : CH 2 , are not capable of this reaction. (8) Some acids have been synthetically prepared by Perkin's reaction. This is readily executed with benzene derivatives. It proceeds with difficulty in the fatty 278 ORGANIC CHEMISTRY. series. It consists in letting the aldehydes act upon a mixture of acetic anhydride and sodium acetate (compare Cinnamic Acid) : C 6 H 13 CHO -f CH 3 . CO a Na = C 6 H 13 . CH = CH . CO 2 Na -f H 2 O. CEnanthol Nonylenic Acid. /3-Dimethylacrylic acid is obtained from acetone, malonic acid and acetic anhy- dride (B. 27, 1574). Pyroracemic acid acts analogously with sodium acetate ; carbon dioxide splits off and crotonic acid results (B. 18, 987). Methods of formation, dependent upon the breaking-down of long carbon chains : (9) The decomposition of unsaturated fi-ketonic acids, synthetically prepared by the introduction of unsaturated radicals into aceto-acetic esters. Allyl aceto-acetic ester yields allyl acetic acid (p. 284). 1 lo) Decomposition of unsaturated malonic acids, containing the two carboxyl groups attached to the same carbon atom (p. 241) : CH 3 . CH : C(CO 2 H) 2 = CH 3 . CH : CH . CO 2 H -f CO 2 . Ethidene-malonic Acid Crotonic Acid. (11) Unsaturated /3y-acids are prepared by distilling y-lactone /3-carboxylic acids, alkylized paraconic acids (B. 23, R. 91). In the same manner yd-unsaturated acids result from the cMactone-y-carbonic acids (B. 29, 2367) : CO 2 H _ CQo -y p a Methyl para- CH 3' CH . CH . CH 2 - -^ CH, . CH : CH . CH 2 . CO 2 H conic Acid, O -CO Ethidene-propionic Acid C 2 H 3 y p * S-Caprolactone- CH. . CH . C . CH 2 . CH 2 > CH. . CH : CH . CH 2 . CH, . CO,H y-carboxylic Acid, O CO yfi-Hexenic Acid. Isomerism. An isomeride of acrylic acid is not known, or possible. The second member of the series has three structurally isomeric, open- carbon chain modifications : (i)CH 3 .CH = CH.C0 2 H; (2)CH 2 = CH . CH 2 . CO 2 H ; (3) CH 2 = In fact, there are three crotonic acids the ordinary solid crotonic acid, isocrotonic acid and methylacrylic acid. Formerly, formula 2 was ascribed to isocrotonic acid. There is, however, much favoring the view that both acids the ordinary solid crotonic acid and iso- crotonic acid have the same formula. Hence it is assumed that cro- tonic and isocrotonic acids are merely geometric, stereo- or space-isomer- ides. Compare crotonic acids, p. 282. Numerous pairs of isomerides, where differences may be similarly indicated, attach themselves to crotonic and isocrotonic acids an- gelic and tiglic acids; oleic and ela'idic acid ; erucic and brassidic acids. The monocarboxylic acids of tri-, tetra-, penta-, and hexamethy- lene are structurally isomeric with the acids C 3 H 5 . CO 2 H, C 4 H 7 CO 2 H, OLEIC ACIDS, OLEF1NE MONOCARBOXYLIC ACIDS. 279 C 5 H 9 CO. 2 H, C 6 H H CO. 2 H. Further, the trimethylene carboxylic acid, /-IT >CH . CO 2 H, is isomeric with the three crotonic acids, and Crl 2 CH tctramethylene carboxylic acid, CH 2 <^ H 2 >CHCO 2 H, etc., with the acids C 4 H 7 CO 2 H. Compare p. 89. Properties and Transpositions. Like the saturated acids in their en- tire character, the unsaturated derivatives are, however, distinguished by their ability to take up additional atoms. They unite the proper ties of a fatty acid with those of an olefine. (1) On combining with two hydrogen atoms they/ ^Become fatty acids. The lower members, as a general thing, combine readily with the H 2 evolved in the action of zinc upon dilute sulphuric acid ; while the higher remain unaffected. Sodium amalgam apparently only reduces those acids in which the carboxyl group is in union with the doubly-linked pair of carbon atoms (B. 22, R. 376). All 'may be hydrogenized, however, by heating with hydriodic acid and phosphorus. (2) They, combine with halogen hydrides, forming monohalogen fatty acids. In so doing the halogen atom attaches itself as far as possible from the carboxyl group (p. 274). (3) They unite with the halogens to form dihalogen fatty acids (p. 274). All these transformations have already been given as methods of forming fatty acids and their halogen derivatives. (4) Ammonia converts the olefine carboxylic acids into amido-fatty acids ; crotonic acid yields /3-amidobutyric acid. Hydrazine and phenylhydrazine deport themselves similarly with the same compounds. (5 ) Diazoacetic ester combines with the olefine carboxylic esters to produce pyra- zoline carboxylic ester; acrylic ester and diazoacetic ester yield 3.4-pyrazoline car- boxylic ester (see this) (Buchner, A. 273, 222). (6) The behavior of unsaturated acids toward alkalies is especially noteworthy. (a) When heated to 100, with KOH or NaOH, they frequently absorb the ele- ments of water and pass into oxy-acids. Thus, from acrylic acid we obtain a-lactic acid (CH 2 : CH . CO 2 H -f H 2 O "= CH 3 . CH(OH) . CO 2 H), and .malic from fumaric acid, etc. (b] /?/- Unsaturated acids rearrange themselves to a/?-unsaturated acids (Fittig, A. 283, 47, 269; B. 28, R. 140) when they are boiled with caustic alkali; the double union is made to take a new position : CH 3 . CII 2 . CH = CH . CH 2 . COOH > CH 3 . CH, . CH 2 . CH : CH . COOH. Hydrosorbic Acid n-Butylidene Acetic Acid. (?) When fused with potassium or sodium hydroxide their double union is severed and two monobasic fatty acids result : CH 2 : CH . CO 2 H -f 2H. 2 O = CH 2 O 2 -f CH 3 . CO 2 H -f H 2 Acrylic Acid Formic Acid Acetic Acid CH 3 CH : CH . CO. 2 H -(- 2H 2 = CH 3 . CO 2 H -f CH 3 . CO 2 H -f H 2 . Crotonic Acid Acetic Acid Acetic Acid. (CH 3 ) 2 C : CH . CH 2 CO 2 H - > (CH 3 ) 2 C . CH 2 . Pyroterebic Acid Isocaprola 280 ORGANIC CHEMISTRY. The decomposition occasioned by fusion with alkali is not a reaction which can be applied in ascertaining constitution, because under the influence of the alkali there may occur a displacement or rearrange- ment of the double union. (7) Oxidizing agents like chromic acid, nitric acid and permanganate of potash have the same effect as alkalies, (a) The group linked to carboxyl is usually further oxi- dized, and thus a dibasic acid results. (^) When carefully oxidized with permanganate, the unsaturated acids sustain an alteration similar to that of the defines ; dioxy-acids result (Fittig, B. 21, 1887). CH 3 .CH : C(C 2 H 5 )C0 2 H + O + H 2 O = CH 3 CH(OH)_C(OH)(C 2 H 5 )CO 2 H a-Ethyl Crotouic Acid a-Ethyl-/3-methyl Glyceric Acid. (8) /9^-Unsaturated acids when heated with dilute sulphuric acid change to ^-lactones : C . CH 2 . CH 2 . COO Isocaprolactone. i. Acrylic Acid \_Propen- A cid~\, CH 2 : CH . CO 2 H, melting at 7 and boiling at 139-140, is obtained according to the general methods: (1) From /S-chlor-, /2-brom-, or /9 iodo-propionic acid by the action of alcoholic potash or lead oxide. (2) From a/3-dibrompropionic acid by the action of zinc and sul- phuric acid, or potassium iodide. (3) By heating /9-oxypropionic acid (hydracrylic acid). The best method consists in oxidizing acrolei'n with silver oxide, or by the transposition of acrole'in, by successive treatment with hydro- chloric and nitric acid, into /?-chlorpropionicacid, and the subsequent decomposition of this acid by caustic alkali (B. 26, R. 777). Acrylic acid is a liquid with an odor like that of acetic acid. It is miscible with water. If allowed to stand for some time, it is trans- formed into a solid polymeride. By protracted heating on the water- bath with zinc and sulphuric acid it is converted into propionic add. This change does not occur in the cold. It combines with bromine to form afl dibrompropionic acid, and with the halogen hydrides to yield /? substitution products of propionic acid (p. 275). If fused with caustic alkalies, it is broken up into acetic and formic acids. The silver salt, C 3 H 3 O 2 Ag, consists of shining needles. The lead salt, (C 3 H 3 - O 2 ). ; Pb, crystallizes in long, silky, glistening needles. The ethyl ester, C 3 H 3 O 2 . C 2 H 5 , obtained from the ester of a/?-dibrompropionic acid by means of zinc and sulphuric acid, is a pungent-smelling liquid boiling at 101-102. The methyl ester boils at 85, and after some time polymerizes to a solid mass. Acryl chloride, CH 2 : CH.CO.C1, boils at 75-76; acrylic anhydride [CH 2 :- CH .CO]. 2 O, boils at 97 (35 mm.) ; a cry I amide, CH 2 : CH . CONH.,, melts at 84- 85, and acrylnitrile, vinyl cyanide, CH 2 : CH . CN, boils at 78 (B."a6, R. 776). Substitution Products. There are twoisomeric forms of mono- and di-substituted acrylic acids. rt-Chloracrylic Acid, CH 2 : CC1 . CO 2 H, results when a/3- and also aa-dichlor- propionic acids are heated with alcoholic potash. It melts at 64-65. It combines with HC1 at 100 to produce n/3-dichlorpropionic acid (B. 10, 1499 ; 18, 244). /9-Chloracrylic Acid is produced together with dichloracrylic acid in the reduc- OLE1C ACIDS, OLEFINE MONOCARBOXYL1C ACIDS. 281 tion of chloralide with zinc and hydrochloric acid (A. 203, 83; 239, 263), also from propiolic acid, C 3 H 2 O 2 (p. 287), by the addition of HC1. It melts at 84 (A. 203, 83). It unites with HC1 to /?$-dichlorpropionic acid. The ethyl ester boils at 146. a-Bromacrylic Acid melts at 69-70. /3-Bromacrylic Acid melts at 115-116. ft lodoacrylic Acid, C 3 H 3 IO 2 , is known in two modifications, one melting at 139-140, the other at 65 (B. 19, 542). a/3-Dichloracrylic Acid melts at 87. /3/3-Dichloracrylic Acid melts at 76-77. a/3-Dibromacrylic Acid and /3/3-Dibromacrylic Acid both melt at 85-86. a/3 Di-iodo-acrylic Acid melts at 106 ; /2/3-Di-iodo-acrylic Acid melts at 133 (B. 18,2284). Trichloracrylic Acid melts at 76. Tribromacrylic Acid melts at 117-118. 2. Crotonic Acids, C 3 H 5 .CO 2 H. In the introduction to the olefine carboxylic acids the isomerism of the crotonic acids was made evident, and it was shown that the cause of the difference between crotonic and isocrotonic or quartenylic acid was sought in the different arrangement of the atoms in the molecules of the two acids, in the sense of the following formulas (A. 248, 281) : HCC0 2 H HC.C0 2 H HC . CH 3 CH 3 CH Crotonic Acid Isocrotonic or Quartenylic Acid. (Plane Symmetric Config.) (Axial Symmetric Config.) The ordinary solid crotonic acid is the m-crotonic acid, because it can be reduced by means of sodium amalgam to tetrolic acid (B. 22, 1183) ; and isocrotonic acid would then be the cis-trans- crotonic acid (p. 51). (However, the experimental basis for the determination of the so-called configurations are very uncertain ; compare B. 25, R. 855, 856; J. pr. Ch. [2] 46, 402. Furthermore, the unitary nature of isocrotonic acid has again been thrown in doubt; compare B. 26, 108 ; and also A. 268, 16 ; 283, 47 ; B. 29, 1639). The melting and boiling points of both crotonic acids and their monochlor- and dichlor-substitution products are presented below in a tabular form : (I ) Crotonic Acid CI ^{>C : C<^ O 2 H m. p. 72; b. p. 180. (la) a-Chlorcrotonic Acid (i) /3-Chlorcrotonic Acid j>C : C< 2 " 94; " 200. (if) a-Bromcrotonic Acid CI J| >C : C<^ H " 106.5. (irf)/?-Bromcrotonic Acid C gp>C : C^ ^ " 95. (2 ) Isocrotonic Acid C ^>C : C<^ 2H liquid "75 (23 mm.). (20) a-Chlorisocrotonic Acid CI ^>C : C<^ H m. p. 66.5. (2l>) /3-Chlorisocrotonic Acid c ^>C:C<^ iU 59; "195. TT PO M (2r) a-Bromisocrotonic Acid CI j >C:C C = C C(OH) . CO 2 H (its ester). Tiglic acid melts at 64.5 and boils at 198. Its ethyl ester boils at 152. Bro- mine converts it into two dibromides (A. 250, 240 ; 259, I ; 272, I ; 273, 127 ; 274, 99). For their constitution, compare B. 24, R. 668. The three possible acids, C 4 H 7 CO 2 H, with normal structure are also known (Fittig, A. 283, 47; B. 27, 2658). Propili- dene Acetic Acid, a/3-pentenic acid, CH 3 . CH 2 . CH : CH . CO 2 H., m. p. 10, b. p. 201, is formed together with y-oxyvaleric acid on boiling ethidene propionic acid with soda, as well as with malonic acid, propionic aldehyde and acetic anhydride, together with /3y-pentenic acid. Its dibromide melts at 56. Ethidene propionic 284 ORGANIC CHEMISTRY. acid, /?y-pentenic acid, CH 3 . CH : CH . CH 2 CO 2 H, b. p. 194, is best prepared by the distillation of methyl paraconic acid. Its dibromide melts at 65. Allyl-acetic Acid, yd-Pentenic Acid, CH 2 : CH . CH 2 . CH 2 . CO 2 H, obtained on heating allyl malonic acid, boils at 187. Dimethyl Acrylic Acid, (CH 3 ) 2 C : CH . CO 2 H,is obtained (i) from /3-oxy-isova- leric acid, (CH 3 ) 2 . C(OH) . CO 2 H, by distillation ; (2) from acetone and malonic acid by means of acetic anhydride (B. 27, 1574) ; (3) from its ester, produced when a-brom isovaleric acid ester is heated with diethylaniline (A. 280, 252). See B. 29, R. 956, for its derivatives. It melts at 70. (4) Hexenic Acids, C 6 H 10 Cy The normal acids belonging in this class are Hydro- and Isohydrosorbic. Hydrosorbic Acid, Propylidene-propionic Acid, /3y-hexenic acid, CH 3 . CH 2 . - CH : CH . CH 2 . CO 2 H, boiling at 208, is obtained from ethyl-paraconic acid, CH 3 . - CH 2 .CH.CH(CO 2 H)CH 2 Co6, according to method 10 (p. 278); hence it is probably a /3y-unsaturated acid. It is the first reduction product of sorbic acid, CH 3 CH : CH . CH : CH . CO 2 H. During the reduction a shifting of the double union occurs. On boiling hydrosorbic acid with caustic soda, it passes into the isomeride whose formation one might expect in the reduction of sorbic acid into isohydrosorbic acid, or butylidene-acetic acid, afi-hexenic acid, CH 3 CH 2 CH 2 CH :- CHCO 2 H, melting at 33 and boiling at 216 (B. 24, 83). When its bromine addi- tion product is boiled with water, oxycaprolactone and homolaevulinic acid result (A. 268, 69). y6-Hexenic acid, CH 3 . CH : CH . CH 2 . CH 2 . CO 2 H, melts at o. Consult method of formation 10, page 278. See B. 29, R. 667 for a/3- and /ty- isohexenic acids. Pyroterebic Acid, (CH 3 ) 2 C : CH . CH 2 . CO 2 H, and Teracrylic Acid, C 3 H 7 .- CH : CH . CH 2 . CO 2 H, b. p. 218 (A. 208, 37, 39), belong to the acids C 6 H ]0 O 2 and C 7 H 12 O 2 . They deserve notice because of their genetic connection with two oxi- dation products of turpentine oil terebic acid and terpenylic acid which will be considered later. See A. 283, 129 ; 288, 176, for /3y- and aft-isoheptenic acids. Pyroterebic acid is changed by protracted boiling or by HBr to isomeric isocapro- lactone : (CH 3 ) 2 .C.CH 2 .CH 2 O CO Teracrylic Acid is converted by HBr into the isomeric lactone of y-oxyheptoic acid, C 7 H 13 (OH)O 2 heptolactone. Nonylenic Acid, CH 3 (CH 2 ) 6 CH : CH . CO 2 H, from cenanthol by general method of formation 7, page 277. Decylenic Acid, C 6 H 13 . CH = CH. CH 2 . CO 2 H, formed from hexylparaconic acid according to general method of formation 10, page 278. Undecylenic Acid, CH 2 = CH(CH 2 ) 8 CO 2 H, is produced by distilling castor oil under reduced pressure. It yields sebacic acid, (CH 2 ) 8 (CO 2 H^ 2 (see this) (B. 19, R- 338 ; I9 2224), upon oxidation. It melts at 24.5, and boils at 165 (15 mm ). When its dibromide, melting at 38, is incompletely decomposed by alcoholic potash, Dehydroundecylenic Acid, CH = C[CH 2 ] 8 CO 2 H, melting at 43, is obtained, which, fused at 180 with caustic potash, changes ioUndecolicAcid, CH 3 . C : C[CH 2 ] 7 CO 2 H, melting at 59 (B. 29, 2232). Higher Olefine Monocarboxylic Acids. To ascertain the point of the doubly linked carbon atoms in the higher olefine monocarboxylic acids, the latter are converted into their corresponding acetylene monocarbonic acids (p. 287), which, in turn, are oxidized and split open at the point of triple carbon union, or they are changed to ketone carboxylic acids, and these are then broken down. Thus, oleic acid yields stearolic acid, which may be oxidized to azelaic acid, C 7 H 13 (CO 2 H) 2 , and pelargonic acid, C 8 H 17 CO 2 H. This would mean that in stearolic acid the carbon atoms 9 and 10 are united by three bonds, and that OLEIC ACIDS, OLEFJNE MONOCARBOXYLIC ACIDS. 285 they are the atoms which in oleic acid are in double union. This conclusion is con- firmed by the conversion of stearolic acid, by means of concentrated sulphuric acid, into ketostearic acid, whose oxime undergoes the Beckmann rearrangement at 400, as the result of the action of concentrated sulphuric acid. Two acid amides result, which are decomposed by fuming hydrochloric acid, the one into octylamine and sebacic acid, the other into pelargonic acid and 9-aminononanic acid (B. 27, 172) : Oleic Acid C 8 H 17 CH : CH[CH 2 ] 7 CO 2 H > C 8 H 17 CHBr.CHBr[CH 2 ] 7 CO 2 H Stearolic Acid C 8 H 17 C=C[CH 2 ] 7 CO 2 H > C 8 H 17 CO . CH 2 [CH 2 ] 7 CO 2 H / Ketostearic Acid VL Ketoxime- C 8 H 17 CN(OH)[CH 2 ] 8 CO 2 H stearic Acid " V )L /\ C 8 H 17 NHCO[CH 2 ] 8 C0 2 H C 8 H 17 CO . NH[CH 2 ] 8 CO 2 H C 8 H 17 NH 2 [CH 2 ] 8 (C0 2 H) 2 C 8 H 17 CO 2 H NH 2 [CH 2 ] 8 CO 2 H Octylamine Sebacic Acid Pelargonic Acid g-Aminononanic Acid. The constitution of hypogaeic and erucic acids has been determined in the same manner. Hypogaeic Acid, CH 3 [CH 2 ] 7 CH : CH[CH 2 ] 5 CO 2 H, found as glycerol ester in earthnut oil (from the fruit of Arachis hypogcea], crystallizes in needles, and melts at 33 and boils at 236 (15 mm.). It results when stearolic acid is fused with KOH at 200 (B. 27, 3397). Oleic Acid, OleinAdd, 8 H> C:C <[CH 2 ] 7 CO 2 H = C i8 H 34O2, melt- ing at 14 and boiling at 223 (10 mm.), occurs as glycerol ester (triolein) in nearly all fats, especially in 'the oils, as olive oil, almond oil, cod-liver oil, etc. It is obtained in large quantities as a by- product in the manufacture of stearin candles (p. 253). In preparing oleic acid, olive or mandel oil is saponified with potash and the aqueous solution of the potassium salts precipitated with sugar of lead. The lead salts which separate are dried and extracted with ether, when lead oleate dissolves, leaving as insoluble the lead salts of all other fatty acids. Mix the ethereal solution with hydrochloric acid, filter off the lead chloride, and concentrate the liquid. To purify the acid obtained in this way, fractionate it under strongly diminished pressure. Oleic acid in a pure condition is odorless, and does not redden litmus. On exposure to the air it oxidizes, becomes yellow, and acquires a rancid odor. Nitric acid oxidizes it with formation of all the lower fatty acids from capric to acetic, and at the same time dibasic acids, like sebacic acid, are produced. A permanganate solution oxidizes it to azelaic acid, C 9 H 16 O 4 . Moderated oxidation produces dioxystearic acid (see this). It unites with bromine to form liquid dibromstearic acid, C 18 H 34 Br. 2 O 2 , which is converted by alcoholic KOH into monobromoleic acid, C^H^BrO-j, and then into stearoleic acid (p. 288). Nitrous acid changes oleic into the isomeric crystalline 286 ORGANIC CHEMISTRY. Elaidic Acid, *>C:C<*, melting at SI G and boil . ing at 225 (10 mm.). With bromine it yields the dibromide, C 18 H 34 Br 2 O 2 , which melts at 27, and when acted upon with sodium amalgam, passes back into elaidic acid. Iso-oleic acid, C 18 H 34 O 2 , melting at 44-45, is obtained from the Hi-addition pro- duct of oleic acid iodostearic acid when it is treated with alcoholic potash, or from oxystearic acid, formed from oleic acid by the action of cone, sulphuric acid, when it is distilled under reduced pressure (B. 21, R. 398; 21, 1878; 27, R. 576). Hydriodic acid reduces oleic and elaidic acids to stearic acid. Oleic, elaidic, and iso-oleic acids, when fused with caustic potash, break down into palmitic acid and acetic acid. This is, however, a reaction that can not be accepted as proving that the double union in the three acids holds the same position. The common view is that oleic and elaidic acids are stereo-isomerides, and that iso-oleic is a structural isomer- ide of the other two acids. Bromine converts the three acids into three different dibrom- stearic acids. Care- fully oxidized with potassium permanganate, they yield three different dioxy stearic acids. Erucic Acid, C 8 H i?>C: C Brassidic Acid, rw H >C:CCH . OH. It combines with bromine to a solid dibromide. When heated with HI (iodine and phosphorus), it is transformed into iodoleic acid, C 18 H 33 IO 2 , which yields stearic acid when treated with zinc and hydrochloric acid (B. 29, 806). ACETYLENE CARBOXYLIC ACIDS. 287 The point of double union between the carbon atoms in ricinoleic acid is ascertained as in the case of oleic acid : (l) By transposition into ricinstearolic acid, melting at 53; (2) and this into keto-oxystearic acid, melting at 84 ; (3) finally, the breaking-down of the oxime of the latter acid (B. 27, 3121). Nitrous acid converts ricinoleic acid into isomeric ricinelaldic acid. This melts at 53 C. (see B. ax, 2735 ; 27, R. 629). Rapinic Acid, C 18 H 34 O 2 , occurs as glycerol ester in rape oil (B. 29, R. 673). Unsaturated Acids, C n H 2n _ S CO 2 H. The acids of this series contain either a trebly linked pair of carbon atoms, e.g., like acetylene (p. 95), or two doubly linked pairs of carbon atoms, as in the diolefines. They are, therefore, distinguished as acetylene monocarboxylic acids : propiolic acid series and diolefine monocarboxylic acids. C. ACETYLENE CARBOXYLIC ACIDS. Methods of Formation. i. (a) By the action of alcoholic potash upon the brom-addition products of the oleic acids, and () the mono- halogen substitution products of the oleic acids. This Js similar to the formation of the acetylenes from the dihalogen addition products and the monohalogen substitution products. 2. From the sodium derivatives of the mono-alkyl acetylenes by the action of CO 2 : CH 3 . C = CNa-f CO 2 = CH 3 C = C . CO 2 Na. Like the acetylenes, they are capable of saturating 2 and 4 univalent atoms. Propiolic Acid, CH i C.CO 2 H, Propargylic Acid [Propin-Acid], melting at -\- 6 and boiling with decomposition at 144 (p. 132), corresponds to propargyl alcohol. The potassium salt, C 3 HKO 2 -f- H 2 O, is produced from the primary potassium salt of acetylene dicarboxylic acid, when its aqueous solution is heated: C . COoH CH + C0 2 . C . CO 2 K C . CO 2 K Acetic acid results in like manner from malonic acid (p. 244). The aqueous solution of the salt is precipitated by ammoniacal silver and cuprous chloride solutions, with formation of explosive metallic derivatives. By prolonged boiling with water the potassium salt is decomposed into acetylene and potassium carbonate. Free propiolic acid, liberated from the potassium salt, is a liquid with an odor resembling that of glacial acetic acid. The acid dissolves readily in water, alcohol, and ether, and reduces silver and platinum salts. Exposed to sunlight (away from air contact) it polymerizes to trimesic acid, 3C 2 H . CO 2 H = C 6 H 3 (CO 2 H) 3 . Sodium amalgam converts it into propionic acid. It forms /3-halogen acrylic acids with the halogen acids (p. 281) (B. 19, 543), and with the halogens yields a/3-dihalogen- aciylic acids. The ethyl ester boils at 119. With ammoniacal cuprous chloride it unites to a stable yellow-colored compound. Zinc and sulphuric acid reduce it to ethyl propar- gylic ester (p. 136) (B. 18, 2271). Chlorpropiolic Acid, CC1 = C.CO 2 H, and Brompropiolic Acid, C 3 BrHO 2 , have been obtained as barium salts from dichloracrylic and mucobromic acids, 288 ORGANIC CHEMISTRY. C 3 H 2 C1 2 O 2 and C 4 H 3 Br 2 O 3 . lodopropiolic Acid is obtained by saponifying its ethyl ester, melting at 68. It melts at 140. The ethyl ester may be prepared from the Cu derivative of propiolic ester (see above) by the action of iodine. The three acids decompose readily into carbon dioxide and spon- taneously inflammable chloracetylene, CC1 = CH, bromacetylene and iodoacetylene. The addition of haloid acids leads to /5/9-dihalogen- acrylic acids, while the halogens form trihalogen-acrylic acids. Carbon dioxide converts the sodium compounds of the correspond- ing alkyl acetylenes into the following homologues of propiolic acid (B. 12, 853; J. pr. Ch. [2] 37, 417): M. P. B. P. Tetrolic Acid, Methyl- acetylene Carboxylic Acid CH 3 C = C . CO 2 H 76 203 Ethyl - acetylene Carboxylic Acid CH 3 .CH 2 .C = C.CO 2 H 80 n-Propyl -acetylene Carbox- ylic Acid CH 3 .CH 2 .CH 2 .C = C.C0 2 H 27 125 Isopropyl-acetylene Carbox- (20 mm.) ylic Acid (CH 3 ) 2 CH.C==C.C0 2 H 38 107 n - Butyl - acetylene Carbox- (20 mm. ) ylic Acid CH 3 . [CH 2 ] 3 C==C . CO 2 H liquid 136 ^ (20 mm.) Of these, Tetrolic Acid has been the most thoroughly investigated, and is obtained from ft chlorcrotonic acid and /3-chlorisocrotonic acid when these are boiled with potash. At 210 the acid decomposes into CO 2 and allylene, C 3 H 4 (B. 27, R. 751). Potassium permanganate oxidizes it to acetic and oxalic acids. It combines with HC1 and HBr, forming /3-chlorcrotonic acid and /3-bromcrotonic acid (B. 22, R. 51; 21, R. 243). With bromine, in sunlight, it yields dibromcrotonic acid, melting at 120, whereas in the dark the halogen produces a dibrom-acid, melting at 94 (B. 28, 1877). a/5/3-Trichlorbutyric acid (p. 276) upon the loss of HC1 yields two dichlorcrotonic acids, one melting at 75 and the other at 92 (B. 28, 2665). These are two acids which are produced when chlorine acts upon tetrolic acid. Several higher homologues of propiolic acid have been prepared by the action of alcoholic potash upon the brom-addition products of the higher olefine monocarboxylic acids (p. 278) : Undecolic Acid, C U H 18 O 2 , obtained from undecylenic acid (p. 284), fuses at 59.5. Stearolic Acid, C 18 H 32 O 2 (constitution, see p. 285), is obtained from oleic and elaidic acids. It melts at 48. Behenolic Acid, C 22 H 40 O. 2 (constitution, see p. 286), from the bromides of erucic and brassidic acids, melts at 57-5. On warm- ing the last two acids with fuming nitric acid they yield the monobasic acids : stear- oxylic, or y.io-dioxystearic acid, CH 3 [CH 2 ] 7 CO. CO[CH 2 ] 7 CO 2 H, melting at 86, and behenoxylic, or l^.l^-dioxobehenic acid, CH 3 [CH 2 ] 7 CO . CO . [CH 2 ] U CO 2 H, melting at 96 (B. 28, 276). Sulphuric acid con verts stearolic acid into ketostearic acid, and behenolic acid into ketobrassidic acid (B. 26, 1867), whose oximes are then transposed by the sulphuric acid into C 8 H 17 CO . NH[CH 2 ] 8 CO 2 H (p. 285). (Oxidation, compare erucic and brassidic acids, p. 286.) D. DIOLEFINE CARBOXYLIC ACIDS. Butdiene Carboxylic Acid, CH 2 : CH . CH : CHCO 2 H, melting at 102, is formed, together with ethidene propionic acid (p. 283), by the reduction of perchlorbutdiene carboxylic acid, CC1 2 : CC1 . CC1 : CC1 . CO 2 H, melting at 97, and perchlorbutine DIHYDRIC ALCOHOLS OR GLYCOLS. 289 carboxylic acid, CC1 3 . C \ C . CC1 2 . CO 2 H, melting at 127. These are products of decomposition resulting from the two hexa-chlor-R-pentenes upon treatment with alkali (B. 28, 1644). Sorbic Acid, CH 3 CH : CH . CH : CH . CO 2 H, is obtained from sobinol, a lactone of parasorbic acid (see this), occurring, together with malic acid, in the juice of unripe mountain-ash berries (from Sorbus aucuparia] (A. no, 129), on boiling with caustic soda, or with hydrochloric acid (B. 27, 351). Potassium permanganate oxidizes it to aldehyde and racemic acid (see this), which establishes the constitution of the acid (B. 23,2377; 24, 85): CH 3 .CH:CH.CH:CH.CO 2 H -f H 2 O + 4O = CH 3 .CHO + CO 2 H.(CH.OH) 2 .CO 2 H. Sorbic Acid Racemic Acid. The ethyl ester boils at 195.. Nascent hydrogen converts the acid into hydro- sorbic acid. Diallylacetic Acid, (CH 2 : CH . CH 2 ) 2 CH . CO 2 H, is obtained from ethyl diallyl- aceto-acetate and diallyl malonic acid. It boils at 227. Nitric acid oxidizes it to tricarballylic acid, (CO 2 H . CH 2 ) 2 CHCO 2 H). Geranic Acid belongs to the class of olefine dicarboxylic acids. It will be de- scribed together with the olefine terpene bodies. IV. DIHYDRIC ALCOHOLS OR GLYCOLS, AND THEIR OXIDATION PRODUCTS. The monohydric alcohols, with their oxidation products, the alde- hydes, the ketones, and the monocarboxylic acids, with their deriva- tives, were discussed in the preceding section. Closely allied to these are the dihydric alcohols or glycols, and such compounds as may be considered oxidation products of the glycols. The glycols are derived from the hydrocarbons by the replacement of two hydrogen atoms attached to two different carbon atoms by two hydroxyls. In the case of the monohydric alcohols we distinguished three classes primary, secondary, and tertiary alcohols. With the glycols the classes are twice as numerous. The compounds, which may be considered as oxidation products of the glycols, contain either two similar, reactive, atomic groups e. g. : the dialdehydes (glyoxal, CHO.CHO), the dikctones (diacetyl, CH 3 . CO . CO . CH 3 ), the dicarboxylic acids (oxalic acid, COOH . COOH), and therefore manifest double the typical properties of the oxidation products of the monohydric alcohols compounds of double function ; or they contain two different reactive atomic groups in the same molecule, and have, therefore, the typical properties of different 25 290 ORGANIC CHEMISTRY. families of compounds. The following bodies have such a mixed function : Aldehyde Alcohols (Glycolylaldehyde, CH a OH. CHO) Ketone Alcohols (Acetylcarbinol, CH 2 OH . CO . CH 3 ) Aldehyde Ketones (Pyroracemic Aldehyde, CH 3 . CO . CHO) Alcohol Acids or Oxydtids (Gly collie Acid, CH 2 . OH . COOH) Aldehydic Acids (Glyoxylic Acid, CHO. CO 2 H) Ketonic Acids (Pyroracemic Acid, CH 3 CO . COOH). Four families alcohols, aldehydes, ketones, and monocarboxylic acids occur with the monohydric alcohols and their oxidation products, while in the case of the dihydric alcohols and their oxidation products ten classes of derivatives are known. The successive series in which these ten classes will be discussed readily follow, if their systematic interdependence be developed similarly to that of the univalent alcohols and their oxidation products. MONOHYDRIC ALCOHOLS AND THEIR OXIDATION PRODUCTS. la. Primary Alcohols, 2. Aldehydes, 4. Monocarboxylic Acids. \b. Secondary " 3. Ketones, ic. Tertiary " DIHYDRIC ALCOHOLS AND THEIR OXIDATION PRODUCTS. la. Diprimary Glycols, 2a. prim. Oxyaldehydes, 4. Dialdehydes, CH 2 . OH Glycol \b. Prim. sec. Glycols, \c. Prim. tert. Glycols, id. Disecond. Glycols, le. Sec. tert. Glycols, I/. Ditert. Glycols. CHO CH 2 OH Glycolylaldehyde CHO CHO Glyoxal 2b. sec. Oxyaldehydes, 30. prim. Oxyketones, 5. Aldehydketones, 2.c. tert. Oxyaldehydes, 3/>. sec. Oxyketones, 6. Diketones, 3O Ethylene Oxide I ' I 2 Diethylene Oxide, CH 2 CH 2 . O . CH 2 and also sulphur- and nitrogen- compounds corresponding to diethylene oxide : 'CH 2 . S . CH 2 CH 2 . NH . CH 2 CH 2 . NH . CH 2 iH 2 .S.(:H 2 CH 2 . O. (*:H 2 CH 2 .NH.CH 2 Diethylene Bisulphide Diethyleneimide Oxide Diethyleneimide. Methods of Formation. The first three methods proceed from the defines, and lead, according to the constitution of the latter, to glycols of every description. The halogen addition products of the olefines the alkylen haloids may be regarded as the haloid acid esters of the glycols. When these are acted upon by alkalies, with the purpose of exchanging hydroxyl for their halogen, they split off a halogen hydride and pass first into monohalogen olefines and then into acetylenes. It was Wurtz who observed that it was only necessary to treat the alkylen haloids with acetates in order to reach the acetic esters of the glycols, and then, by saponification with alkalies, to obtain the glycols. DIHYDRIC ALCOHOLS OR GLYCOLS. 293 (1) By heating the alkylen haloids (p. 102) with silver acetate (and glacial acetic acid), or with potassium acetate in alcoholic solution : C 2 H J 2 + 2C 2 H 3 2 . Ag = C 2 H 4 < ; J + 2Agl. Ethylene Diacetate. Inasmuch as the alkylens are made from monohydric alcohols by the withdrawal of water, and are transformed by the addition of halogens into alkylen haloids, the preceding reaction may be regarded as a method of converting monohydric alcohols into dihydric alcohols or glycols. The resulting acetic esters are purified by distillation, and then saponified by KOH or baryta water : C * H *<0'. C 2 H 3 3 + 2KOH = C * H *CH 2 CH 2 Br CH 2 CN CH 2 .CH 2 .NH 2 CH 2 CH 2 . OH Trimethylene Trimethylene Pentamethylene Pentamethylene Bromide Cyanide Diamine Glycol. (5) Some glycols have been prepared by the reduction of the cor- responding aldehydes or ketones ; thus, ay-butylene glycol by the reduc- tion of a Idol ; ad-hexylene glycol from Y-acetobutyl-alcohol}, etc. Nucleus-synthetic Methods. (6) Disecondary glycols are produced on treating certain aldehydes with alcoholic potash, when two aldehyde molecules are reduced to a disecondary glycol, and one is 294 ORGANIC CHEMISTRY. oxidized to the corresponding carboxylic acid (B. 29, R. 350). Iso- butyraldehyde yielded symmetrical di-isopropyl ethylene glycol : f (~*~\j \ C^T 3 (CH 3 ) 2 CH . CHO + KOH = (CH 3 ) 2 . CHCOOK + ( CH *)* C H . CHOH. (7) Ditertiary glycols result, together with secondary alcohols, in the reduction of ketones (p. 212). In this manner pinacone or tetra- methyl-ethyl glycol (p. 296) was made from acetone (Friedel) : 2(CH,) 2 CO -f 2H = (CH 3 ) 2 .COFT Properties. The glycols are neutral, thick liquids, holding, as far as their properties are concerned, a place intermediate between the monohydric alcohols and trihydric glycerol. The solubility of a compound in water increases according to the accumulation of OH groups in it, and it will be correspondingly less soluble in alcohol, and especially in ether. There will be also an appreciable rise in the boiling temperature, while the body acquires at the same time a sweet taste, inasmuch as there occurs a gradual transition from the hydro- carbons to the sugars. In accord with this, the glycols have a sweetish taste, are very easily soluble in water, slightly soluble in ether, and boil much higher (about 100) than the corresponding monohydric alcohols. Behavior. (i) With dehydrating agents, see alkylen oxides: cyclic esters of the glycols. 2d Method of formation, page 298. (2) Many glycols, when oxidized, especially the primary, pass into the corresponding oxidation products ; see ethylene glycol ; others break down with the splitting-off of carbon chains. (3) Conduct toward the haloid acids, nitric acid, concentrated sulphuric acid, acid chlorides and acid anhydrides; see esters of the glycols, page 300. i. Ethylene Glycol, [i.2-Ethandiol], CH 2 OH . CH 2 OH, melt- ing at 11.5, boiling at 197.5, with a specific gravity of 1.125(0), is miscible with water and alcohol. Ether dissolves but small quanti- ties of it. It may be obtained from ethylene through ethylene bromide (ethy- lene chloride) [general method of formation, p. 293] or by direct oxidation, and also from ethylene oxide by the absorption of water : 9 H 2>0 + FLO = C H S ' OH . CH, CH 2 . OH Preparation, Boil 188 grams ethylene bromide, 133 grams K 2 CO 3 and I liter of water, with a return condenser, until all the ethylene bromide is dissolved (A. 192, 240 and 250). It would be more advantageous to take a little water and add ethylene bromide and the carbonate in portions, filtering from time to time from the separated potassium bromide. Deportment (i) On heating ethylene glycol with zinc chloride DIHYDRIC ALCOHOLS OR GLYCOLS. 295 water is eliminated and acetaldehyde (and crotonaldehyde) formed. (2) Nitric acid oxidizes glycol to glycollic acid and glyoxal, glyoxylic acid and oxalic acid. The first oxidation product, glycolaldehyde (see this), is further oxidized too rapidly : CH 2 .OH COOH CHO COOH COOH CH 2 .OH~ "^CH 2 OH CHO ~ "^CHO "^COOH* Glycol Glycollic Acid Glyoxal (see this) Glyoxylic Acid Oxalic Acid. (3) And when glycol is heated, together with caustic potash, to 250, it is oxidized to oxalic acid with evolution of hydrogen. (4) Heated to 160 with concentrated hydrochloric acid, glycolchlor- hydrin results; which at 200 is converted into ethylene chloride. (5) The latter is also produced when PC1 5 acts upon glycol. (6) Nitric-sulphuric acid changes glycol to glycol dinitrate. (7) Concentrated sulphuric acid and glycol yield glycol sulphate. (8) The acid chlorides or acid anhydrides produce mono- and di- esters of glycol. Gly 'collates : Metallic sodium dissolves in glycol, forming sodium glycollate, C 2 H * boils at C 2 H 5 . CO . COC 2 H 5 C 3 H 7 . C . CO . C 3 H 7 io8(lomm.). Di-n-propylacetylene Glycol Dibutyrate, DibutyryUp ^ p ~Q p ^ , boils at 119-130 (12 mm.). Di-isobutyl Acetylene Glycol Di-isovalerate, Di-isovaleryl, (CH 3 ) 2 . CH . CH 2 . C OCOC 4 H 9 fe u 145-155 (12 mm.). Butyroin and (CH 3 ) 2 . CH . CH 2 . C O . COC 4 H 9 ' isovaleroin, the corresponding a-ketone alcohols (see this), are produced, and not the alkyl acetylene glycols, when these three compounds are saponified. Hexa-di-indiol, CH 2 (OH)C C C C . CH 2 . OH, melting at 1 11, is a diacetyl- ene glycol. It is formed by the oxidation of the precipitate from propargyl alcohol and ammoniacal cupric chloride with potassium ferricyanide (Ch. C. 1897, I, 281). GLYCOL DERIVATIVES. 1. ALCOHOL ETHERS OF THE GLYCOLS. A. The alcohol-ethers are obtained from the metallic glycollates by the action of the alkyl iodides. The monoalkyl ethers of the glycols arise also in the union of ethylene oxide with alcohol : c i H 4 Ethyl Ether. (First Ether of Glycol)i <-tt 2 ^ H s B. Cyclic Ethers of the Glycols, Alkylen Oxides. By assuming the exit of a second molecule of water from diethylene glycol, the CH CH first ether of glycol, there arises Diethylene Oxide, CX^r jj 2 CH 2 -^^' me ^ tm S at 9 and boiling at 102; a polymeric ethylene oxide (compare polymeric aldehydes), the second ether of glycol. It is obtained from the red, crystalline brom- addition product of ethylene oxide, (C 2 H 4 O) 2 Br 2 , melting at 65 and boiling at 95, when it is y^TT (~\ treated with mercuric oxide. Ethylene Methyl Ether, 2 ' >CH 2 , boiling at 78, {-s Aln " is obtained from trioxymethylene, ethylene glycol and ferric chloride (B. 28, R. 109). f^T~T O Ethylene Ethidene Ether, 2 ' ^CH . CH 3 , boiling at 82.5, results from the union of ethylene oxide and acetaldehyde. It is isomeric with diethylene oxide. The latter is a cyclic double ether. But ethylene oxide, 2 >O, the third ether of CH 2 glycol (Wiirtz), is the simpler cyclic ether of glycol. The simple cyclic ethers of the glycols, the alkylen oxides, are readily produced in various ways, depending upon whether the two OH-groups are attached to adja- cent carbon atoms or not. Alkylen oxides, in which the O-atoms are in union with adjacent carbon atoms, are termed the a-alkylen oxides, while the others are the /?-, y-, ^-alkylen oxides, (i) Ethylene oxide itself and the ethylene oxides, as well as the /3-alkylen oxides (trimethylene oxide), are prepared by the action of caustic potash upon the chlor- or brom-hydrins, the monohaloid esters of the respective glycols : CHCI KOH = 2 KC1 (2) The y- and J-alkylen oxides (y-pentylene oxide, pentamethylene oxide] are formed when the glycols are heated with sulphuric acid (B. 18, 3285 ; 19, 2843) : CH 2 .CH 2 OH 7 CH 2 .CH 2 CH / H2SO * > CH ' X CH 2 . CH 2 OH The a-glycols, under like treatment, lose water and yield either unsaturated alcohols, aldehydes, or pinacolines, depending upon their constitution (p. 214). The ethylene oxide ring is easily ruptured, hence ethylene oxide enters into addition reactions quite as freely as its isomeride acetaldehyde. The rings of tetra- and pentamethylene oxides, however, are far more stable. These can only be broken up by the haloid acids. (~*TT Ethylene Oxide, H 2 > boiling at 12.5, sp. gravity 0.898 (o), isomeric with acetaldehyde, CH 3 .CHO, is a pleasantly smelling, ethereal, mobile liquid, with a neutral reaction, yet able to gradually precipitate metallic hydroxides from many metallic salts (Magn, Rot. und Refract., see B. 26, R. 497) : CH 2 CH 2 . OH OH MgCl 2 + 2 C - H >0 + 2H 2 = 2 tH ^ cl + Mg< QH GLYCOL DERIVATIVES. 299 Ethylene oxide is characterized by its additive power. (l) It combines with water and slowly yields glycol. (2) Nascent hydrogen converts it into ethyl alcohol. (3) The halogen hydrides unite with it to form halohydrins, the monohaloid esters of the glycols. (4, a) With alcohol it yields glycol monoethyl ether ; (b] with glycol it forms diethylene glycol ; (c) and with the latter it combines to triethylene glycol. (5) It forms ethylene ethidene ether (see above) with aldehyde. (6) Acetic acid and ethylene oxide form glycol monacetate, and (7) with acetic anhydride the product is glycol diacetate. (8) Sodium bisulphite changes it to sodium isethionate. (9) Ammonia changes ethylene oxide to oxethylamine. (lo) With hydrocyanic acid it forms the nitrile of ethylene lactic acid or hydracrylic acid, from which hydrochloric acid produces the ethylene lactic acid itself. Caustic potash polymerizes ethylene oxide at 50-60 (B. 28, R. 293). For comparison , the following additive reactions of ethylene oxide and aldehyde are arranged side by side : S0 3 HK ^ C H 2 . OH S0 3 HK , OH '*vc. < S03K NH 3 ^ OH -f ^H 3 . L.fK^TT CNH CH 2 . OH CHoCH a-Propylene Oxide, >O, boils at 35, Isobutylene Oxide, i CH 2 CH 2 at 51-52, sym. Dimethyl-ethylene Oxide at 82; trimethylethylene oxide at 75-76; tetramethyl-ethylene oxide, boiling at 95-96, combines with water, with the evolution of much heat, and yields pinacone (p. 296). CFT Trimethylene Oxide, CH 2 O, boils at 50. Preparation, p. 205. y~iTT |^T-T Tetramethylene Oxide, Tetrahydro-furfurane, i 2 >O, boils at 57 (B. CH 2 . CH, /-iTT f'HYr''Fr \ 25, R. 912). y-Pentylene Oxide, H * ' CR >O* boils at 77 (p. 296; B. 22, 2571). prj pTir Pentamethylene Oxide, CH 2 <^ 2 ' CH>' boils at 82 ( B ' 2 7 R ' J 97)' /--Hexylenc Oxide, CH 2 < a ">O 3 , boiling at 104, does not combine with ^H-o . Vvxirt ammonia (B. 18, 3283). Adaendum. Fur fur ane corresponds to tetramethylene oxide. It may be con- sidered as the cyclic ether of an unknown, unsaturated glycol. It is not probable that this glycol could exist; it would be more probable that it would rearrange itself to succindialdehyde, and this in turn to y-butyrolactone (see this) : CH 2 .CH 2 OH CH 2 .CH 2 CH = CHOH CH = CH CH 2 OH CH 2 .CH 2 { CH = CHOH CH = CH 2 CH 2 Tetramethylene Tetramethylene Unknown Furfurane. Glycol Oxide Acetpropyl alcohol, furthermore, has yielded i-methyldihydrofurfurane the 300 ORGANIC CHEMISTRY. alcohol corresponding to it would very probably at once rearrange itself into acetyl- propyl alcohol (p. 52) : CH 2 .CO.CH 8 CH = C(OH).CH 3 CH = C-CH S CH 2 . CH 2 OH CH 2 CH 2 OH CH 2 CH 2 Acetopropyl Alcohol Unknown i-Methyldihydrofurfurane. By the substitution of sulphur and again of the NH-group for oxygen in furfurane the products are thiofurfurane, which, from its remarkable resemblance to benzene, has been called Thiophene, and Pyrrol. Notwithstanding that the manner of union in the rings of these heterocyclic com- pounds is not definitely known, it is possible to refer many bodies to them : CH = CH CH = CH CH = CH tH = CH> fcH = CH> S fcH = CH Furfurane Thiophene Pyrrol. All of them contain rings, and they will be discussed later in conjunction with related classes of heterocyclic derivatives. 2. ESTERS OF THE DIHYDRIC ALCOHOLS OR GLYCOLS. A. Esters of Inorganic Acids. (a] Haloid Esters of the Glycols. The glycols and monobasic acids yield neutral and basic esters. The dihalogen substitution products of the paraffins are the neutral or secondary haloid esters of the glycols. The halogen atoms in them are attached to different carbon atoms. They are isomeric with the aldehyde haloids (p. 201) and the ketone haloids (p. 2 1 6), having an equally large carbon content : CH 2 C1 CH 2 C1 CHC1 2 CH 3 CHC1 S CH 2 are isomeric with CH 2 and CC1 2 CH 3 CH 2 C1 CH 3 CH 3 Propylene Trimethylene Propidene Chloracetol Chloride Chloride Chloride (p. 217). (p. 201) The basic or primary haloid esters of the glycols are the halohydrins. These are obtained : (I) When the glycols are treated with hydrochloric and hydrobromic acids: H When heated with HI, a more extensive reaction occurs. Ethyl iodide (p. 142) is obtained from ethylene glycol. (2) They can be obtained, too, by the direct addition of hypochlorous acid to the alkylens (B. 18, 1767, 2287) : II C + C10H = (CH 3 ) 2 (3) By the action of haloid acids upon ethylene oxide and its homologues : ESTERS OF THE DIHYDRIC ALCOHOLS OR GLYCOLS. 301 Glycolchlorhydrin, Ethylene chlorhydrin, CH 2 C1 . CH 2 OH, boils at 128. Glycolbromhydrin boils at 147. Trit!iethyleneglycolchlorhydrin,Ctt\ . CH 2 . - CH 2 OH, boiling at 160, is obtained by means of HC1 from trimethylene glycol. a-Propylene glycol-a-chlorhydrin, CH 3 . CH(OH)CH 2 C1, boiling at 127, is prepared from allyl chloride by the action of dilute sulphuric acid. a-Propylene glycol-$-chlor- hydrin, CH 3 . CHC1 . CH 2 OH, boiling at 127, is formed when C1OH adds itself to propylene. hobutylene glycol-$-chlorhydrin, Cl . C(CH 3 ) 2 . CH 2 OH, boils at 128- 130. Ethyl chlor-ethe r, ft-ethoxy-a-chlorbutane, boiling at 141, is formed by the interaction of a, ft -dick lorether and zinc ethide (B. 28, 3111). The primary haloid esters can also be considered as substitution products of the monohydric alcohols. Glycol chlorhydrin would be chlor-ethyl alcohol, (i) Nas- cent hydrogen converts them into primary alcohols. (2) Oxidizing agents convert them into halogen fatty acids, e. g., glycol chlorhydrin yields monochloracetic acid ; trimethylene-glycol chlorhydrin yields fi-chlorpropionic acid ; a-propylene glycol-/3- chlorhydrin yields a-chlorpropionic acid, and isobutylene glycol-/?-chlorhydrm yields a-chlorisobutyric acid. (3) They change to alkylen oxides under the influence of alkalies. (4) Basic esters of the glycols are produced when they combine with salts of organic acids; e.g., glycol chlorhydrin and potassium acetate yield glycol mono- acetate, CH 3 . COO . CH 2 . CH 2 OH. (5) Potassium cyanide changes them to nitriles of the oxyacids. Neutral ffaloid Esters of the Glycols are very important starting- points in the preparation of the glycols; compare methods i and 4 for the formation of glycols, p. 293. Methods of Formation. (i) By the addition of halogens to the olefines e. g., ethylene ethylene chloride, bromide and iodide result : CH 2 CH 2 C1 CH 2 CH 2 Br CH 2 CH 2 I II 2 + C1 2 = | ; || 2 + Br 2 = | ; || 2 + I 2 = | 2 . CH 2 CH 2 C1 CH 2 CH 2 Br CH 2 CH 2 I (2) By the substitution of paraffins and monphalogen paraffins : CH 3 cu CH 2 C1 Clg CH 2 C1 CH 3 " L ^'. CH 3 (Fe) ' CH 2 Cl' (3) By the addition of halogen hydrides to monohalogen olefines. In this instance much will depend on the temperature, concentration, and other conditions, as te whether both or only one of the two possible isomerides is formed : /- TTT... CH 2 Br CH 2 Br' (4) By the action of HC1, HBr or HI upon glycols and glycol chlorhydrins. The second OH will be replaced with more difficulty, and at a higher temperature, than the first. (5) When PC1 5 acts upon glycols. (6) From bromides, iodides can be obtained by KI, and chlorides by means of HgCl 2 . Properties. The simple dichlor- and dibrom-esters of the glycols, or olefine dichlorides and dibromides, volatilize without decom- position. The di-iodides decompose readily in the light, and when ^TTT) r^T-TT^*- itir 2 dil. HBr Cone. HBr 302 ORGANIC CHEMISTRY. distilled break down into olefines and iodine. The ethylene dihaloids have a very pleasant odor. Transformations. (i) The dihalogen paraffins are converted into olefines by sodium : CILC1 CHCL - 2Na and | 11^ ^ CH 2 C1 CH 3 CII 2 The production of trimethylene from trimethylene bromide and sodium or zinc is noteworthy : f~*\x T> v^irio (2) Nascent hydrogen converts both di and mono-halogen paraffins into paraffins. This is the reverse of substitution retrogressive substi- tution (p. 101). (3) When digested with alcoholic potash, a halogen hydride splits off, and monohalogen olefines and acetylenes result (p. 95). (4) Suitable reagents change dihalogen paraffins into the corre- sponding glycols (p. 293) or their esters. (5) Ammonia produces alkylen diamines. (6) Potassium cyanide converts them into the nitriles of monohalogen acids, and the nitriles of dicarboxylic acids. These are classes of bodies whose connection with the glycols is indicated by the dihalogen paraffins : CH 2 Br ^ CH 2 . OH CiH 2 .OH CH 2 . CN i "^ CH 2 Br CH 2 . CN Ethylene Cyanide CH 2 2 CH 2 .COOH " CH 2 . COOH Ethylene Succinic Acid. Ethylene Haloids Ethylene Chloride, Elayl Chloride, Oil of the Dutch chemists, CH 2 C1 . CH 2 C1, boiling at 84, can be prepared (A. 94, 245) by conducting ethylene into a gently heated mixture of 2 parts of manganese dioxide, 3 parts of salt, 4 parts of water and 5 parts of sulphuric acid. It is insoluble in water, has an agreeable odor, sweet taste, and the sp.gr. 1.2808 (at 4). Ethylene Bromide, CH 2 Br . CH 2 Br, melting at -j- 9 and boiling at 131, is formed when ethylene is introduced into bromine, contained in a wide condenser bent at right angles, and covered with a layer of water (A. 168, 64). It is also produced when ethyl bromide, bro- mine and iron wire are heated to 100 (B. 24, 4249). Ethylene Iodide, CH 2 I . CH 2 I, melting at 81, is formed on con- ducting ethylene into a paste of iodine and ethyl alcohol (J. 1864, 345)- ESTERS OF THE DIHYDRIC ALCOHOLS OR GLYCOLS. 303 History of the Alkylen Haloids. The four Dutch chemists, Deiman, Pacts van Troostwyk, Bondt and Lauwerenburgh, while studying the action of chlorine upon ethylene, first obtained ethylene chloride in 1795 as an oil-forming reaction product. Hence they called ethylene "gas huileux," oily gas, a name which Fourcroy altered to " gas olefiant," " oil-forming gas" (see Roscoe and Schorlemmer, Org. Ch., i, 647). This phrase subsequently gave the name " olffines" to the series. Balard, the discoverer of bromine, obtained ethylene bromide in 1826 on allowing bromine to act upon ethylene (A.chim. phys. [2] 32, 375). Faraday, in 1821, prepared ethylene iodide by acting on ethylene with iodine in sunlight. Propylene Haloids. \.2-Dihalogen propanes, CH 3 .CHX. CH 2 X, and Tri- methylene Haloids, \.-$-Dihalogen propanes, CH 2 X . CH 2 CH 2 X. The propylene lialoids are produced by the addition of the halogens to propylene, and of halogen hydrides to allyl haloids at 100. Trimethylene bromide results from allyl bromide and hydrogen bromide at 20. HgCl 2 and KI convert the bromide into the chloride and trimethylene iodide. Propylene chloride, b. p., 97 ; Trimethylene chloride, b. p., 119. " bromide, " 141; * bromide, " 165. " iodide decomposes; ' iodide decomposes. Higher Homologous Polymethylene Bromides (J. pr. Ch. [2] 39, 542 ; B. 27, R. 735). Tetramethylene Bromide, l.4-Dibrombutane, CH 2 Br[CH 2 ] 2 CH 2 Br, boils at 189. Pentamethylene Bromide, 1.5-Dibrompentane, CH 2 Br[CH 2 ] 3 CH 2 Br, boils at 205. Hexamethylene Bromide, 1.6-Dibromhexane, CH 2 Br[CH 2 ] 4 CH 2 Br, boils at 243. Sodium converts these compounds into cycloparaffins, just as sodium and tri- methylene bromide yield trimethylene. Sodium malonic esters, sodium acetoacetic esters, and polymethylene bromides produce cycloparaffin carboxylic esters (see these). Mixed, neutral haloid esters of the glycols, containing two different halogen atoms, are also known. Ethylene Nitrate, C 2 H 4 (O , NO 2 ) 2 , is produced on heating ethylene iodide with silver nitrate in alcoholic solution, or by dissolving glycol in a mixture of concen- trated sulphuric and nitric acids : C 2 H 4 (OH) 2 + 2N0 2 . OH = C 2 H 4 (0 . NO 2 > 2 + 2H 2 O. This reaction is characteristic of all hydroxyl compounds (the poly hydric alcohols and polyhydric acids} ; the hydrogen of hydroxyl is replaced by the NO^ group. The nitrate is a yellowish liquid, insoluble in water, and has a specific gravity of 1.483 at 8. It explodes when heated (like the so-called nitroglycerol). The alkalies saponify the esters with formation of nitric acid and glycol. OH Glycol or Ethylene hydroxy sulphuric Acid, C 2 H 4 <^ ^0 Q^J, is produced on heating glycol with sulphuric acid. It is perfectly similar to ethyl sulphuric acid (p. 145), and decomposes, when boiled with water or alkalies, into glycol and sul- phuric acid. B. Esters of Carbonic Acids. In studying the fatty acids we learned the method of forming esters with mono- hydric alcohols. The same methods serve for the production of esters of the fatty acids with dihydric alcohols or glycols. (i) From the haloid esters of the glycols: halohydrins and alkylen haloids with fatty-acid salts : CH 2 C1 CH 5 .C0. 2 K = C ^' -f KC1. CH 2 .OCOCH 3 ^ (2) From glycols by means of free acids, acid chlorides or acid anhydrides. 304 ORGANIC CHEMISTRY. (3) There also remains that ester formation resulting from the addition of acids and acid anhydrides to alkylen oxides, just as acid anhydrides add themselves to aldehydes : CH 2 CH 2 .O.COCH 3 CH 3 . CHO + (C 2 H 3 0) 2 = CH 3 . CH (OCOCH 3 ) 2 . Glycol Mono-acetate, C 2 H 4 S, melting at 112 and boiling at 200, is formed from ethylene mercaptan, ethylene bromide, and sodium ethylate. When ethylene bromide is digested with alcoholic sodium sulphide, a polymeric ethylene sulphide, (C 2 H 4 S) n , melting at 145, is produced at first. This is a white, amorphous powder, insoluble in the ordinary solvents. Pro- tracted boiling with phenol changes it to diethylene disulphide (A. 240, 305 ; B. 19, 3263; 20, 2967). (e) Ethylene Mercaptals and Ethylene Mercaptols are similarly produced from ethylene mercaptan by the action of aldehydes, ketones, and HC1, just as the mer- captals (p. 218) and the mercaptols (p. 204) are obtained from mercaptans (B. 21, I473) ' CH S Ethylene-dithioethidene, i ,>CH . CH 3 , boils at 173. CH 2 S C. Diethylene Tetrasulphide, C 2 H 4 C 2 H 4 , is produced by the action of the halogens, upon ethylene thiohydrate (or sulphuryl chloride or hydroxylamine. It is a white, amorphous powder, melting at 150 (B. 21, 1470). D. Sulphine Derivatives. Ethyl iodide and diethylene disulphide unite to sulphiniodide, (C 2 H 4 S) 2 C 2 H 5 I. r~* T T ^ (~* T~T Ethyl Sulphurane, i 5 , is produced on distilling this iodide with CH 2 . S . C 2 H 5 sodium hydroxide. The closed ring of diethylene disulphide is broken. The union of the derivatives of diethylene disulphide with the higher alkyl iodides yields homologous compounds known as sulphuranes. They are the alkyl vinyl ethers of thioethylene (B. 20, 2967 ; A. 240, 305). E. Sulphones. The disulphones are produced when the open and the cyclic disulphides are oxidized by potassium permanganate. All sulphones, in which sulphone groups are attached to two adjacent carbon atoms, can be saponified (Stuffer's law, B. 26, 1125). CH, . SO 2 . C,H (a) Open Sulphones : Ethylene-diethylsulphone, i ^ , has been CH 2 . SO 2 . C 2 H 5 obtained (i) from ethylene dithioethyl; (2) from ethylene bromide by the action of 2 molecules of sodium ethyl sulphinate, and (3) from sodium ethylene disulphinate by the action of 2 molecules of ethyl bromide. The sexivalence of sulphur in the sulphones is thus proved (B. 21, R. 102). It yields colorless needles, melting at 137. r^T-T QC\ (b} Cyclic Sulphones : Trimethylene Disulphone, i 2 >CH 2 , melts at CH 2 . SO 2 204-205. SO Diethylene Disulphone, C 2 H 4 C 2 H 4 (B. 26, 1124; 27, 3043), results from the oxidation of diethylene disulphide. F. Sulphone-sulphinic Acids and Disulphinic Acids. Oxethylsulphone methylene-sttlphinic Acid, HO . CH 2 . CH 2 . SO 2 . CH 2 . SO . OH, is a syrup-like mass. Its barium salt is formed when trimethylene disulphone is de- composed by baryta water. When the solution is evaporated below 40, a cyclic ester results, which recalls the lactones, the cyclic esters of the oxycarboxylic acids : Oxethyhulphomethylene Sulphinic Lactone, i 2 ' ' 2 >CH 2 , melts at 164 (B. L^lTn * ^ * OVJrt 26 306 ORGANIC CHEMISTRY. CH 2 . SO . OH 27, 3043). Ethylene Disulphinic Acid, ^ , is formed by the reduction of CH 2 . SO . OH ethylene disulphonic acid (p. 307). G. Sulphonic Acids. Isethionic Acid, u , Ethylene Hydrinsulphonic Acid, CH 2 . SO 3 H Oxyethylsulphonic Acid, is isomeric with ethyl sulphuric acid, SO H 4>S0 2 . 3 Elhionic Acid, The constitution of this acid would indicate it to be both a sulphonic acid and primary sulphuric ester. It is therefore dibasic, and on boiling with water readily yields sulphuric and isethionic acids. It results when carbyl sulphate takes up water. Carbyl Szdphate, C 2 H 4 S 2 O 6 (A. 223, 210), is formed when the vapors of SO 3 are passed through anhydrous alcohol. It is also produced in the direct union of ethy- Ethylene Disulphonic Acid, TT , is easily soluble in water, melts, when anhydrous, at 94, and is formed in the oxidation of glycol mercaptan and ethylene sulphocyanide with concentrated nitric acid; by the action of fuming sulphuric acid upon alcohol or ether, and by boiling ethylene bromide with a concentrated solution of potassium sulphite (compare ethylene disulphinic acid, p. 306). 4. NITROGEN DERIVATIVES OF THE GLYCOLS. A. Nitroso-compounds. The addition-products from the defines and nitrosyl chloride belong in this group (compare the terpenes). 308 ORGANIC CHEMISTRY. Tetramethyl-ethylene-nitrosylchloride, (CH 3 ) 2 C(NO) . CC1(CH 3 ) 2 , melting at 121, has a blue 'Color, and a somewhat penetrating camphor-like odor. The hydrocarbon in hydrochloric-alcoholic solution is mixed, while cooling, with sodium nitrite (B. 27, 455 ; R- 467). B. Nitro-compounds. Only one nitro-derivative of glycol the primary body is known. Nitro-ethyl Alcohol, glycolnitrohydrin, CH 2 (NO 2 ) . CH 2 . OH, results from the interaction of glycoliodhydrin and silver nitrite. It is a heavy oil. Nitro-isopropyl Alcohol, CH 3 . CH(OH)CH 2 NO 2 , boiling at 112 (30 mm.), sp. gr. 1.191 (18), is a colorless liquid. It is formed in the condensation of equimolecular quantities of acetaldehyde and nitromethane by means of alkali (B. 28, R. 606). i.^-Dinitropropane, NO 2 CH 2 . CH 2 . CH 2 NO 2 , is the only known secondary nitro- body. It is obtained from trimethylene iodide. All other dinitro-paraffins contain the two nitro-groups joined to the same carbon atom. They are derivatives of the alde- hydes or ketones (p. 158). C. Amines and Ammonium Compounds of the Glycols. There are two series of amines, derived from the glycols, and corre- sponding to the two series of glycollates, esters, mercaptans, etc. : HO. CH 2 .CH 3 .OH, HO . CH 2 . CH 2 . NH 2 , and NH 2 CH 2 . CH 2 . NH 2 Glycol Oxyethylamine Ethylene Diamine. Therefore the amines of the glycols break down into two classes: (i) The oxyalkylamines and their derivatives ; (2) thealkylendiamines and their derivatives. (a) Oxalkyl Bases, or Hydramines and their derivatives. Methods of forma- tion: (i) Action of ammonia upon the halohydrins ; (2) by the union of ammonia and alkylen oxides. In these two reactions the products are primary, secondary and tertiary oxyalkyl bases, e.g. : CH 2 CH 2 . OH i >O -j- NH 3 = i Oxyethylamine or Amidoethyl alcohol (p. 124) CH 2 CH 9 . NH 9 f^TJ 2 i TT 2 >0 -f NH 3 == r2' 2 |S5) ' rS 2 > NH Dioxyethylamine or Imidoethyl Alcohol CH 2 ^H-v^ 1 *) ^"2 CH 2 CH 2 (OH).CH 3 I TT >O -f NH 3 = CH 2 (OH) . CH 2 _1N Trioxyethylamine or Azoethyl Alcohol. CH 2 CH 2 (OH) . CH 2 / (3) By the action of sulphuric acid upon allylamine with addition of water (B. 16, 532), or by evaporation with nitric acid, when vinylamine, for example, yields oxethylamine. (4) By the application of the phthalimide reaction (p. 162). Alkylen haloids are allowed to act upon potassium phthalimide, the reaction- product being heated with sulphuric acid to 200-230 : The dialkylic Oxyethylamine bases are also called alkamines ; their carboxylic esters, the alke'ines (see tropein) (B. 15, 1143). NITROGEN DERIVATIVES OF THE GLYCOLS. 309 The oxyethylamine bases are separated by fractional crystallization of their HC1- salts, or platinum double salts. They are thick, strongly alkaline liquids, which de- compose upon distillation. Oxy-ethylamine, CH 2 OH . CH 2 . NH 2 , A mido- ethyl Alcohol [2-Aminoethanor], is produced by the usual methods. Oxy-ethylmethylamine, CH 2 OH . CH 2 . NH . CH 3 , results from ethylene chlor- hydrin and methylamine when they are exposed to a temperature of no . It is a liquid, boiling at 130-140. Oxy-ethyldimethylamine, CH 2 OH . CH 2 . N(CH 3 ) 2 , has been obtained from ethylene chlorhydrin and NH(CH 3 ) 2 (B. 14, 2408); also by the breaking-down of methyl morphimethine (B. 27, 1144). For homologues and alkamines of cyclic secondary bases, see B. 14, 1876, 2406; 15, 1143; 28, 3111 ; 29, 1420. The bases obtained from the tertiary amines are especially interesting. Choline is one of them. It is quite important physiologically. Choline, Oxyethyl-trimethyl Ammonium Hydroxide, Bilineurine, C\ T T Sincalin, C 2 H * I - " > I \ CH 2 N(CH 3 ) 3 OH CH 2 N(CH 3 ) 3 OH CH 2 N(CH 3 ) 3 . Its hydrochloride is obtained directly by synthesis, when trimethyl- amine is heated with monochloracetic acid (B. 2, 167 ; 3, 161) : (CH 3 ) 3 N + CH 2 C1 . CO . OH = (CH 8 ),N< H CO OH , and on heating amidoacetic acid (glycocoll), NH 2 . CH 2 . COOH, with methyl iodide, caustic potash and wood spirit. Betaine occurs already formed in the sugar-beet (Scheibler, B. 2, 292 ; 3, 155), Beta vulgaris, hence is present in the molasses from the beet, and makes the latter valuable for the obtainment of trimethyl- amine. It is also found in the leaves and stalks of Lycium barbarum, in cottonseed, and in malt and wheat sprouts (B. 26, 2151). It crystal- lizes with one molecule of water in deliquescent crystals, in which there is present the acid HO . N(CH 3 ) 3 . CH 2 . CO 2 H. At 100 this ammo- nium hydroxide loses one molecule of water, and the cyclic ammo- COO nium salt, | \ , is produced. CH 2 N(CH 3 ) 3 ' Diethyleneimide Oxide, Morpholine, O< 2 ' 2 >NH, is produced when dioxyethylamine is heated to 160 with hydrochloric acid, and upon distillation with caustic potash. See B. 22, 2081, for homologous morpholines. It is assumed that the same atomic grouping exists in morphine as in morpholine, hence the name. Diacetone Alkamine, (CH 3 ^ 2 C(NH 2 )CH 2 . CH . OH . CH 3 , boiling at 174-175, is formed in the reduction of diacetonamine (p. 219) (A. 183, 290). () Halogen Alkylamines, or Haloid Esters of the Oxyalkylamines. In the free state these bodies are soluble in water and not very stable. They easily change to salts of the cyclic imides, e. g. , chloramylamine, C1CH 2 (CH 2 ) 4 NH 2 , become penta- methyleneimide- or piperidine chlorhydrate, CH 2 . (CH 2 ) 4 NH . HC1. Methods of Formation : (i) The addition of a halogen hydride to unsaturated amines, like vinyl - or allylamine, p. 169 (B. 21, 1055 ; 24, 2627, 3220). (2) By the action of halogen hydrides upon oxyalkylamines, see neurine, p. 309 ; NITROGEN DERIVATIVES OF THE GLYCOLS. 3! I (3) when the halogen alkyl phthalimides are heated with haloid acids (B. 21, 2665 ; 22, 2220; 23, 90), e.g. : (2)CO> N ' CH 2CH 2 Br - %- C 6 H 4 Bromethyl-phthalimide o-Phthalic Acid. (4) Or the nitriles of the halogen substituted acids are transposed with sodium phenoxide, reduced, and then heated with an haloid acid (B. 24, 3231 ; 25, 415) : C1CH 2 . CH 2 CH 2 CN -f NaOC 6 H 5 = C 6 H 5 O . CH 2 . CH 2 . CH 2 CN + NaCl 4H 2HC1 C 6 H 5 OCH 2 [CH] 2 CN -^ C 6 H 5 OCH 2 [CH 2 ] 2 CH 2 NH 2 -^C1CH 2 [CH 2 ] 3 NH 2 . HC1. The following are known : Chlor-, l>rom-, and iodoethylamine, ICH 2 .CH 2 NH 2 ; y-Brompropylamine, Br .- CH 2 . CH 2 . CH 2 NH 2 ; $-Brombutylamine, CH 3 CH 2 CHBrCH 2 NH 2 ; y-Chlorbutyl- amine, CH 3 . CHC1 . CH 2 . CH 2 NH 2 (B. 28, 3111); 6-Chlorbutylamine, C1CH 2 [CH 2 ] 3 - NH 2 ; t-Chloramylamine, C1CH 2 (CH 2 ) 4 NH 2 ; $-Methyl-t-chlor-n-amylamine, CH 2 - C1[CH 2 ] 2 CH(CH 3 )CH 2 NH 2 ; fi-n-Propyl-t-chlor-n-amylamine, CH 2 C1[CH 2 ] 2 CH- (C 3 H 7 )CH 2 NH 2 (B. 27, 3509 ; 28, 1197). The four last bodies split off hydrochloric acid and yield tetramethylene and pentamethylene imides (p. 314), or piperidine, /3-pipecoline and /3-propylpiperidine. (c) Oxyethylamine Derivatives Containing Sulphur. Aminoethyl mercap- tan chlorhydrate, HC1 . NH 2 . CH 2 . CH 2 SH, melts at 70-72. Thioethylamine, (NH 2 . CH 2 .CH 2 ) 2 S, boils at 231-233. Diaminofthyl disulphide chlorhydrate, (NH 2 . CH 2 . CH 2 S) 2 2HC1, melts at 253. Diaminoethylsulphone, (NH 2 CH 2 CH 2 ) 2 SO 2 , has been prepared from bromethylphthalimide as the starting-out substance (B. 22, 1138; 24, HI2, 2132, 3101). Taurine, Amidoisethionic Acid, NH 2 . CH 2 . CH 2 . SO 3 H, has already been discussed under isethionic acid (p. 306). (d] Alkylen Diamines. The di-, like the mono-valent alkyls, can replace two hydrogen atoms in two ammonia molecules and produce primary, secondary, and tertiary diamines. These are di-acid bases, and are capable of forming salts by direct union with twcx equivalents of acids. Some of them have been detected with the ptomaines or alkaloids of decay (B. 20, R. 68) and are therefore worthy of note, e. g. , tetramethylene diamine or putrescine, and pentamethylene diamine or cadaverine. Formation: (i) They are prepared by heating the alkylen bromides with alco- holic ammonia to 100 (p. 161) in sealed tubes : C 2 H 4 Br 2 + 2NH 3 = C 2 H 4 <^ . 2H Br Ethylene Bromide v^ ^ T$- Ethylene Diamine 2C 2 H 4 Br 2 + 4NH 3 = NH< 2 ' 2 >NH . 2HBr + 2NH 4 Br Diethylene Diamine C* TT 3 C 2 H 4 Br 2 + 6NH, == N ^ C 2 H* \ N . 2 HBr + 4 NH 4 Br. 24 Triethylene Diamine. To liberate the diamines, the mixture of their HBr-salts is distilled with KOH and the product then fractionated. (2) Another very convenient method for the preparation of diamines is the reduc- 312 ORGANIC CHEMISTRY. tion of (a) alkylen dicyanides or nitriles (see these) with metallic sodium and absolute alcohol (see p. 162 and B. 20, 2215): CN CH 2 NH 2 CH 2 .CN CH 2 .CH 2 .NH 2 I + 8H = |' ; |' + 4 H 2 = I CN CH 2 .NH 2 CH 2 .CN CH 2 .CH 2 .NH 2 Dicyanogen Ethylene Ethylene Tetramethylene Diamine Cyanide Diamine. (b) By the reduction of the oximes, (c] reduction of the hydrazones of the dial- dehydes and diketones, and (d] by the reduction of the dinitroparaffins. In some of these reductions cyclic imides have been observed ; thus, in the reduc- tion of ethylene cyanide in the presence of tetramethylene diamine, tetramethylene imide is formed. (3) From dicarboxylic amides, bromine and caustic potash (B. 27, 511) (p. 163). (4) From dicarboxylic azides ; see hexamethylene diamine, p. 313. (5) From alkylene diphthalimides on heating with HC1 : d)C ^ - H 2)3N< CO(2 / ) )C 6 H 4 4H2Q > HC1.NH 2 .CH 2 .CH 2 .CH 2 NH 2 HC1 Trimethylene Diphthalimide Trimethylenediamine Chlorhydrate. Properties. The alkylen diamines are liquids or low melting solids of peculiar odor, which in the case of those that are volatile is very much like that of ammonia, and recalls piperidine. They fume slightly in the air, and attract carbonic acid. Behavior. Alcohol and acid radicals can be introduced into the amido-groups of the diamines in the same manner as in the amido-groups of the monamines. The production of the dibenzoyl derivatives, e. g. y C 2 H 4 (NH CO . C 6 H 5 ) 2 , upon shaking with benzoyl chloride and caustic soda, is well adapted for the detection of the diamines (B. 21, 2744). Nitrous acid converts them into glycols, at the same time unsaturated alcohols and unsaturated hydrocarbons arise (B. 27, R. 197) Further, the diamines unite directly with water, forming very stable ammonium oxides, which only give up water again when they are distilled over caustic potash (compare pentamethylene diamine) : e aiamine By the exit of ammonia they pass into cyclic imides. Ethylene Diamine, C 2 H 4 < NH 2 , melting at +8.5, boiling at 116.5, com- bines with water to ethylene diamine hydrate, melting at -|-IO and boiling at 118. It reacts strongly alkaline, and has an ammoniacal odor. Nitrous acid converts it into ethylene oxide. Ethylene Dinitramine, NO 2 NHCH 2 . CH 2 NHNO, (B. 22, R. 295). Ethylene diamine and a/3-propylene diamine, like the ortho-diamines of the benzene series, combine with ortho-diketones, e. g., phenanthraquinone and benzil, to form pyrazine derivatives, similar in structure to the quinoxalines. They also unite with the benzaldehydes and benzoketones (B. 20, 276; 21, 2358). Consult B. 27, 1663. for the action of CSC1 2 upon ethylene diamine. Diacetyl-ethylene Diamine consists of colorless needles, melting at 172, When this compound is heated beyond its melting point, water splits off, and there follows an inner condensation that leads to the formation of a cyc\\camidine base, closely allied to the glyoxalines. It is ethyl-ethenyl amidine or methyl glyoxalidine, which under the name Lysidine, m. p. 105 and b. p. 223, has been recommended as a NITROGEN DERIVATIVES OF THE GLYCOLS. 313 solvent for uric acid (B. 28, 1176). The corresponding propylene- and trimethylene- diamine derivatives react similarly : CH 2 . NH . CO . CH 3 CH 2 . NR | = | J>C.CH 8 + CH 3 .C0 2 H. CH 2 .NH.CO.CH 3 CH 2 .N^ Diacetyl-diethylene Ethylene-ethenyl Diamine Amidine. CH, . CH . NH 2 Propylene Diamine, i , boiling at 119-120 (B. 21,2359), has CH 2 . NH 2 been split up by means of d-tartaric acid. 1-Propylene Diamine, [a] D = 19. n, forms a d-tartrate, which is sparingly soluble (B. 28, 1180). Trimethylene Diamine, CH 2 <^ 2 ' ^ 2 , boils at 135-136 (B. 17, 1799 ; 21, 2670). It has been prepared by general methods I and 3 ; also (2d) by reduction of l-3-dinitro-propane (p. 159). Tetramethylene Diamine, \\.\-Diaminobutane\ Putrescine, C 4 H 8 (NH 2 ) 2 , melting at 27, is obtained from ethylene cyanide by general method 2a, and from succinaldehyde dioxime (p. 327) (B. 22, 1970). It is identical with \\\eputrescine (B. 21, 2938), which has been isolated from decaying matter. [i.4-Diaminopentane], CH 3 CH(NH 2 ) . CH 2 . CH 2 . CH 2 . NH 2 , boiling at 172, is formed from the nitrile of pyroracemic acid according to method of formation 2a. (j>- and / r-[2.5-Diaminohexane], CH 3 CH(NH 2 )CH 2 . CH 2 CH(NH 2 )CH 3 , boiling at 175, are formed together from the diphenyl-hydrazone of acetonyl acetone (p. 324) according to method of formation 2c. They sustain a relation to each other similar to that shown by racemic acid and mesotartaric acid (B. 28, 379). [1.4 Diamino-2-Methyl Pentane], CH 3 CH(NH 2 )CH 2 . CH(CH 3 )CH 2 NH 2 , boiling at 175, is obtained from a methyl -levulindialdoxime (p. 298) according to method of formation 2b (B. 23, 1790). Pentamethylene Diamine, Cadaverine, \l.$-Diaminopentane\, J-.TT ^CH 2 . CH 2 . NH, CH 2 S S NH NH NH Diethylene Oxide Diethylene Diethylene-imide Oxide Diethylene-diamine Disulphide Morpholine Piperazine. Diethylene Diamine, Piperazine, Hexahydropyrazine, melting at 104 and boiling at 145-146, was first prepared by the action of ammonia upon ethylene chloride. It is produced by heating ethylene-diamine hydrochloride (B. 21, 758), and by the reduction of (~TJ _ (""TT pyrazine, N \ r ~pt.X N ^' 2 ^> 7 24 )' It is technically made from diphenyl diethylene diamine, the reaction- product of aniline and ethylene bromide, when it is transposed into the p-dinitroso-compound, and the latter then broken down into p-dinitrosophenol and diethylene dia- mine : ^ Diethylene diamine, or piperazine, is a strong base, soluble in water, which upon distillation with zinc dust, changes to pyrazine (see this) (B. 26, R. 441). It is interesting to note that piperazine unites with uric acid to form a salt even more readily soluble than the lithium salt. Hence its strongly alkaline, dilute solution has been recommended as a solvent for uric acid (B. 24, 241). Trimethylene Imide, CH 2 NH, boils from 66-70 (B. 23, 2727). r^i-T /^TT Tetramethylene Imide, Tetrahydropyrrol, Pyrrolidine, ( '' >NH, boil- CH a . CI1 2 ing at 87, is obtained from tetramethylene diamine according to method of ALDEHYDE ALCOHOLS. 315 formation I ; from rf-chlorbutylamine and caustic potash by method 2 (B. 24, 3231), and by the reduction of pyrroline, the first reaction-product of pyrrol (B. 18, 2079), and of succinimide (see succinic acid) (B. 20, 2215) : =CH _^1^ CH, . CH 2>NH _ J H_ > CH 2 . CH CH=CH CH = CH CH 2 .CH 2 Pyrrol Pyrroline Pyrrolidine, Tetramethylene Imide. .Tetramethylene imide has an odor resembling that of piperidine. Tttramethylene-nitrosamine, C 4 H 8 NNO, boils at 214 (B. 21, 290). CH 3 . CH . CH 2 /3-Methyl Pyrrolidine, I >N, boils at 103 (B. 20, 1654). CH, . CH 2 CH 2 .CH(CH 3 ) a-Methyl Pyrrolidine, ( >NH, is obtained fiom y-valerolactam. CH 2 . CH 2 ^^-" It boils at 97. i.4-Dimethyl Pyrrolidine boils at 107 (B. 22, 1859). Pentamethylene Imide, Piperidine, Hexahydropyridine, boiling at 106, is obtained according to methods i, 2 (B. 25, 415) and 3 (p. 314) ; also from piperine (see this), and by the reduction of pyri- dine, into which it passes when it is oxidized : 6H /CH CH V -> X CH 2 .CH 2V CH^ ^N 3 o CH 2 ( 2 \NH. X CH=CH X -^ X CH 2 . CH/ Pyridine Piperidine. Piperidine bears the same relation to pyridine that is sustained by pyrrolidine to pyrrol. Therefore, tetramethylene imide and penta- methylene imide link the pyrrol and pyridine groups to the simple aliphatic substances, the diamines, and their parent bodies, theglycols. The pyrrol and pyridine derivatives will be discussed later in connection with the heterocyclic ring systems, together with allied bodies, and then we shall again return to pyrrolidine and piperidine. 2. ALDEHYDE ALCOHOLS. These contain both an alcoholic hydroxyl group and the aldehyde group CHO, hence their properties are both those of alcohols and aldehydes (p. 189). The addition of 2 H-atoms changes them to glycols, while by oxidation they yield the oxy-acids, containing a like number of carbon atoms. (I) Glycolyl Aldehyde, CH 2 (OH) . CHO, may be considered the first aldehyde of glycol, and glyoxal (p. 320) the second or dialdehyde. It is produced when brom-acetaldehyde is treated with cold baryta water, or when chloracetal is heated with very dilute acids; probably also from dioxymaleic acid (?), an oxidation product of tartaric acid, when it is digested with water at 50-60 (B. 29, R. 919). It is only known in aqueous solution. Bromine water oxidizes it to glycollic acid (see this), and dilute caustic soda condenses it to tetrose (see this) (B. 25, 2552, 2984) ; see aldol. Phenylhydrazine acetate produces the osazone of glyoxal (p. 328). 316 ORGANIC CHEMISTRY. The following bodies, which have been already discussed, are derivatives of glycol aldehyde : CHO CH(OC 2 H 5 ) 2 CHC1 2 CHC1 2 CH 2 Cl(BrI), CH 2 Cl(Br) CH 2 OH CH 2 C1 Monochlor-(brom-, iodo-) Monochlor- Dichlorethyl i.2-Trichlor-ethane Acetaldehyde (p. 198) acetal (p. 200) Alcohol (p. 125) (p. 103). Glycol Acetal, CH 2 OH . CH (O . C 2 H 5 ) 2 , boiling at 167, is obtained from brom- acetal (B. 5, 150). Ethyl Glycol Acetal, C 2 H 5 O . CH 2 . CH(O . C 2 H 5 ) 2 , boils at 168 and is obtained from i.2-dichlorether (p. 135) (B. 5, 150). Phenyl Glycol Acetal, C 6 H 5 O . CH 2 . CH- (O . C 2 H 5 ) 2 , boils at 257 (B. 28, R. 295). Isotriethylin, CH 3 . CH(OC 2 H 5 ) . CH- (O . C 2 H 5 ) 2 , boiling at 85 (ll mm.), is formed when acrolein is digested several days with alcohol at 50 (B. 24, R. 89), and by the action of orthoformic ether upon acrolein (B. 29, 2933). (2) Aldol, CH 3 . CH(OH) . CH 2 . CHO, /?- Oxybutyr aldehyde, boiling at 60-70 (12 mm.), and discovered by Wiirtz in 1872, is obtained by the condensation of acetaldehyde by means of dilute cold hydrochloric acid, and other condensation agents, e.g., CO 3 K 2 (B. 14, 2069 ; 24, R. 89 ; 25, R. 732). Aldol freshly prepared is a colorless, odorless liquid, with a specific gravity of 1.120 at o, and is miscible with water. Aldol distils in a vacuum un decomposed at 100 ; but under atmospheric pressure it loses water and becomes crotonaldehyde. As an aldehyde it will reduce an ammoniacal silver nitrate solu- tion. Heated with silver oxide and water it yields /9-oxybutyric acid, CH 3 .CH(OH).CH 2 .C0 2 H. On standing it polymerizes into para Idol, (C 4 H 8 O 2 ) n , which melts at 80-90. Should the mixture of aldehyde and hydrochloric acid used for the preparation of aldol stand for some time, water separates, and we obtain the so-called dialdan, C 8 H U O 3 . This is a crystalline body which melts at 139 and reduces ammoniacal silver solutions. NITROGEN-CONTAINING DERIVATIVES OF THE ALDEHYDE ALCOHOLS. Ammonia converts aldol in ethereal solution into aldol-ammonia, C 4 H 8 O 2 . NH 3 , a thick syrup, soluble in water. When heated with ammonia we get the bases, C 8 H 15 NO 2 , C 8 H 13 NO (oxytetraldin, see this) and C 8 H n N (collidine). With aniline aldol forms methyl quinoline. (Compare alkylide anilines.) Amidoaldehydes: (i) Amidoacetaldehyde, [Ethanalamine], [2-Amino-et/ianal~\, NH 2 . CH 2 . CHO. This is obtained as a deliquescent hydrochloride when amido- acetal, NH 2 . CH 2 (O . C 2 H 5 ) 2 , boiling at 163, is treated with cold, concentrated hydro- chloric acid. Amido-acetal is produced when chloracetal is treated with ammonia * / f~* TT f '" T T v (B. 25, 2355; 27,3093). Amidoacetaldehyde yields pyrazine, N ^N \CH = CH/ (B. 26, 1830, 2207), when it is oxidized with sublimate. Hydrazide Acetaldehyde (B. 27, 2203). Betalne Aldehyde, (CH 3 ) 3 N . CH 2 . CHO . OH (?) (B. 27, 165), is different from Muscarine (p. 309), which occurs in fly agaric (A^arifus tnusfartus). Isomnscarine, HO. CH 2 . CH(OH)N(CH 3 ) 3 CH (?), is obtained from the addition product of C1OH and neurine (p. 309) with silver oxide (A. 267, 253, 291). SATURATED KETOLS. 317 rf Amidovaleraldehyde, NH 2 . CH 2 . CH 2 . CH 2 . CH 2 . CHO, melting at 39, is obtained from piperidine by the action of H 2 O 2 , and condenses to tetrahydropyridine (B. 25, 2781) when it is heated. Homologous amidoaldehydes are obtained from conine, a- and /3-pipecoline, as well as copellidine, when treated with hydrogen peroxide (B. 28, 2273) : CH 2 NH CH 3 i-Methyl-dihydropyrrol /CH, . CO . CH, NH 3 CH = C\, CH '< -> CH < Tetrahydropicoline. B. UNSATURATED KETOLS, OXYMETHYLENE KETONES. Compounds of this class are obtained from the ketones R . CO . CH 3 and R . CO .- CH 2 R X , together with formic ester in the presence of sodium ethylate. It is very prob- able that at first the sodium compound of diethyl orthoformic acid is formed (p. 233), which is transposed by the ketone, and water is split oft": O . C 2 H 5 C 2 H 5 ONa /OC 2 H 5 (CH 3 ) 2 CO HC< > HOU)C,H, - ^ CH, . CO . CH=CHONa. ^O \ONa These bodies were at first thought to be /3-ketoaldehydes. However, their pro- nounced acid character has shown that they should be regarded as oxymethylene ketones, acivinyl alcohols (Claisen, B. 20, 2191 ; 21, R. 915; 22, 533, 3273 ; 25, 1781). They dissolve in alkaline carbonates, forming stable salts, and give green colored precipitates with copper acetate (B. 22, 1018). Acetic anhydride and UNSATURATED KETOLS. 319 benzoyl chloride converts them as readily in a free state as the phenols into neutral acetates and benzoates, insoluble in alkalies. Their alkali derivatives and ethyl iodide yield oxyethyl ethers, which are saponified by alcoholic alkalies, like the ethers of organic carboxylic acids. These compounds, CO.CH = CH. OH, are the first exceptions to the rule of Erlenmeyer (p. 53), according to which the complex ^>C = CHOH present in open chains must invariably rearrange itself into the aldehyde form ^>CH . CHO. It is shown, on the contrary, that when an hydrogen atom of the methyl or methylene group in acetaldehyde or its homologues, R . CH 2 . CHO, is replaced by an acid radical, a rearrangement of the aldehyde form into the vinyl alcohol form is sure to follow (B. 25, 1781). In conjunction with this explanation it may be mentioned that the alkyl oxy- methylene group e. g. , C 2 H 5 O.CH= may be introduced by means of ortho- formic ester and acetic anhydride into compounds which contain the atomic grouping, CO . CH 2 . CO (B. 26, 2729), e. g., into acetyl acetone, acetoacetic ester and malonic ester. The compounds which result will be described subsequently in their proper places. Oxymethylene Acetone (formerly called formy I acetone, acetoacetic aldehyde], CH 3 - CO.CH = CHOH, boils at about 100, and readily condenses in solution to [I-3-5]- triacetyl benzene, C 6 H 3 [i.3.5-](CO . CH 3 ) 3 (see this). Hydrazine converts it into 3-methyl pyrazole, and phenylhydrazine into i-phenyl-3-methyl pyrazole (see this). Oxymethylene-diethyl ketone, C 2 H 5 CO . C(CH 3 ) = CHOH, melts at 40 and boils at 164-166. NITROGEN-CONTAINING DERIVATIVES OF THE KETONE ALCOHOLS. (l A) Amidoketones of the paraffin series are obtained by the reduction of isoni- troso-ketones with stannous chloride (B. 27, 1037). Amidoacetone, CH 3 . CO . CH 2 - NH 2 , is a brown, thick oil. Amidopropylmethyl ketone, CH 3 COCH(NH 2 )C 2 H 5 , is an oil which solidifies to a crystalline mass. Diacetonamine, (CH 3 ) 2 C(NH 2 )CH 2 . CO . CH 3 . Compare p. 219. These com- pounds, oxidized with sublimate, yield pyrazine derivatives ; thus, amido-acetone / r* { c*\3 \ _ f TT\ passes into N ~7 N > dimethylpyrazine (B. 27, R. 928). The pyra- zines, ketines or aldines will be treated along with the heterocyclic compounds. The hydrochlorides of the a-amidoketones are easily transposed by potassium cyanate into imidazolones, and by potassium sulphocyanide into imidazoly Inter capta us (B. 27, 1042, 2036). Dialkylamidokefones have been prepared in great number by the interaction of chloracetone and secondary amines : Dimethylamido-acetone, (CH 8 ) 2 N . CH 2 . CO . - CH 3 . boils at 123, while Diethylamidoacetone boils at 155 (B. 29, 866). (l B) Unsaturated 8- Amidoketones have been obtained from acetyl acetone (p. 323) by the action of ammonia, primary and secondary alkylamines (B. 26, R. 290). Acetylacetonamine, CH 3 . CO . CH = C(NH 2 )CH 3 , melts at 43 and boils at 209. Acetyl-acetone-ethylamine CH 3 . CO . CH = C(NHC 2 H 5 )CH 3 , boils at 210-215. Acetyl-acetone diethylamine, CH 3 . CO. CH = CN(C,H 5 ) 2 . CH 3 , boils at 155 (24 mm.). (2) Isoxazoles, the anhydrides of the oximes of unsaturated /3-oxyketones and /3-oxyaldehydes will be subsequently treated together with the oximes of the alde- hyde ketones and the diketones (p. 325). (3) a-Halogenketoximes are produced by the action of hydroxylamine upon mono- halogen acetones (p. 216). Chloracetoxime, CH 2 C1. C: N(OH) . CH 3 , boils at 71 (9 mm.); bromaceloxime melts at 36, while iodoacetoxime melts at 64 (B. 29, 550). (4) Alkylen Nitrosates and Nitrosites, produced by the action of nitrogen tetroxide and trioxide upon alkylens, are nitrogen-containing derivatives of the a-ketols (A. 241, 288; 245, 241 ; 248, 161 ; B. 20, R. 638; 21, R. 622), e. g. : 320 ORGANIC CHEMISTRY. -^ ( CH 3)*C N,Q 4 (CH 3 ) 2 C . ON0 2 N 2 3 (CH 3 ) 2 CONO CH CH CH,C: ^-Isoamylene Isoamylene Nitrosate, Isoamylene Nitrosite. Trimethyl Ethylene m. p. 97 When amines act upon these bodies the O . NO 2 group is replaced by the NHR group with the formation of nitrolamines, from which ketoamines can be obtained : (CH 3 ) 2 C ONO 2 C 6 H 5 NH 2 (CH 3 ) 2 C NHC 6 H 5 H 2 O (CH 3 ) 2 C NHC 6 H 5 Amylene Nitroaniline Amylene Ketoanilide. m. p. 131 Potassium cyanide introduces the cyanogen group for the ONO 2 group of the amylene nitrosate, and from the nitrile an oxime acid may be prepared. The latter melts at 97 and breaks down into CO 2 , and methyl isopropyl ketoxime, which would clear up the constitution of these bodies : (CH 3 ) 2 C . ON0 2 (CH 3 ) 2 C . CN (CH 3 ) 2 C . CO 2 H CH 3 C=rNOH~ " CH S C = NOH. > CH S C = NOH /3-Ispamylene Isoamylene Ketoxime-dimethyl Methylisopropyl Nitrosate Isonitrosocyanide Acetoacetic Acid Ketoxime. The nitrosate and nitros'te reactions are important for some of the terpenes (see these). (5) Pyrazoles (see these) are heterocyclic nitrogen-containing derivatives of the unsaturated /?-oxyketones (p. 318), which are obtained from these and hydrazine or phenylhydrazine (see above). 4. DIALDEHYDES. The only known dialdehyde of the fatty series is glyoxal, discovered in 1856 by Debus. Glyoxal, Oxalaldehyde [Ethandial], Diformyl, CHO . CHO, is the dialdehyde of ethylene glycol and oxalic acid, while glycolyl aldehyde (p. 315) represents the first or half aldehyde of ethylene glycol and the aldehyde of glycollic acid : CH 2 OH CH 2 OH CHO CH 2 OH CHO CHO Glycol Glycolyl Aldehyde Glyoxal. Glyoxal, glycollic acid and glyoxylic acid are formed in the careful oxidation of ethylene glycol, ethyl alcohol (B. 14, 2685 ; 17, R. 168), or acetaldehyde with nitric acid. It may also be prepared by trans- posing its sodium salt with sodium bisulphite (B. 24, 3235). On evaporating the solutions the glyoxal is obtained as an amorphous, non-vola- tile mass. It deliquesces in the air. It is very soluble in both alcohol and ether. In this condition it probably represents a hydrate, because methylglyoxal (p. 321) and dimethyl glyoxal (p. 322) are very volatile (B. 21, 809). Deportment : The alkalies convert it, even in the cold, into glycollic acid. In DIKETONES. 32! this change the one CHO group is reduced, while the other is oxidized (compare benzil and benzilic acid) : CHO CH 2 OH tHO +H '= glyoxal, pyroracemic acid, glyoxylic acid, alloxan, dioxytartaric acid, etc., react similarly with the o-phenylenediamines. (2) The glyoxalines are the products of the union of the a-diketones with ammonia and the aldehydes : CH 3 .CO CH 3 C NH. (3) Nucleus-synthetic reactions : a-Diketones, containing a CH 2 -group, together with the CO-group, sustain a rather remarkable condensation when acted upon by the alkalies. Aldols are first produced, and later the quinones (B. 22, 2215 ; 28, 1845) : CH 3 .CO.CO.CH 3 CH 3 .C(OH).CO.CH 3 CH 3 .C.CO.CH yield | and || \ CH 3 .CO.CO.CH 3 CH 2 .CO.CO.CH 3 CH.CO.C.CH 3 . 2 Molecules Diacetyl Diacetyl Aldol p-Xyloquinone. (4) Diacetyl and prussic acid yield the nitrile of dimethyl racemic acid (see gly- oxal) (B. 22, R. 137). Diacetyl, CH 3 . CO . CO . CH 3 , Diketobutane, Dimethyl diketone, dimethyl glyoxal [Butandion], from isonitrosoethylmethylketone, has also been obtained from oxalyldiacetic acid (ketipic acid) by the splitting-off of the carboxyls upon the application of heat (B. 20, 3183), as well as by the oxidation of tetrinic acid (see this) with KMnO 4 (B. 26, 2220 ; A. 288, 27). It is a yellow liquid, with an odor like that of quinone. It boils at 87-89. Tetrachlor-diacetyl, CHC1 2 . CO . CO . CHC1 2 , results in the action of potassium chlorate upon chloranilic acid (together with tetrachloracetone, p. 217). It melts at 84 (B. 22, R. 809 ; 23, R. 20). Tetrabrom-diacetyl (CHBr 2 .CO) 2 (B. 23, 35) and Dibrom-diacetyl, (CH 2 Br . CO) 2 , are produced by the action of bromine upon diacetyl. Acetyl-propionyl, C 2 H 5 . CO . CO . CH 3 , Methyl-ethyl-diketone, [2.3-pentan- dion], from isonitroso-ethylacetone, condenses to duroquinone. It boils at 108. Acetyl-butyryl, [2 3-Hexandion], C 3 H 7 . CO . CO . CH 3 , boils at 128. Acetyl- iso-butyryl, (CH 3 ) 2 CHCO . CO . CH 3 , boils at 115. Acetyl isovaleryl, (CH,),- CHCH 2 COCOCH 3 , boils at 138. Acetyl Iso-caproyl, (CH 3 ) 2 CHCH 2 CH 2 CO- COCH 3 , boils at 163 (B. 22, 2117; 24, 3956). DIKETONES. 323 a-Diketone Dichlorides result in the action of hypochlorous acid upon alkylized acetylenes (p. 97), according to the equation : C 2 II 5 . C : C . CH S -f 2C1OH = C 2 H 5 . CC1 2 . CO . CH 3 + H 2 O. Methyl-a-dichlorpropyl Ketone, C 2 H 5 . CC1 2 . CO . CH 3 , boiling at 138, yields methyl-n-propyl ketone on reduction ; with a potash solution it forms duroquinone, angelic acid (p. 283), and a-ethyl acrylic acid. The two acids result from an intra- molecular atomic rearrangement which recalls that of the formation of benzilic acid from benzil (p. 54). (2) ft- or i.3-Diketones are produced according to two nucleus-synthetic reac- tions: (l) Like the oxymethylene ketones, by the interaction of acetic esters and ketones in the presence of sodium ethylate, or, better, metallic sodium (Claisen, B. 22, 1009 ; 23, R. 40). It is very probable that the formation of a sodium derivative of orthoacetic acid precedes the condensation. Compare oxymethylene ketones (p. 318) and acetoacetic ester (see this) : OC 2 H 5 /OC 2 H 5 CH 3 C^ + C 2 H 5 ONa = CH 3 C^OC 2 H 5 /OC 2 H 5 ' CH 3 ^OC 2 H 5 -f >CHCOCH 3 = CH 3 C(ONa) = CH . CO . CH 3 -f 2 C 2 H 5 OH. (2) By the action of A1C1 3 upon acetyl chloride and the subsequent decomposition of the aluminium derivative. This reaction was discovered by Combes, but correctly interpreted by Gustavson (B. 21, R. 252; 22, 1009): 3 CH 3 COC1 -f A1C1 3 = 3>CH ' CC1 2 ' A1C1 a + 2HC1 Constitution. The /3-diketones, like the oxymethylene ketones, (p. 318), have an acid character. Although the formyl ketones are regarded as oxymethylene deriva- tives, the disposition generally is to assign the salts of the /3-diketones, e.g. , CH 3 . - CO . CH = C(ONa)CH 3 , the vinyl alcohol formula, retaining for the free ketones, however, the diketo- formula. Compare also acetoacetic ester (see this), and formyl- acetic ester (see this) (A. 277, 162). The molecular refraction is an argument in favor of this view (B 25, 3074). Deportment. Their alkali salts are precipitated by copper acetate. Ferric chloride imparts an intense red color to their alcoholic solution. See pp. 327, 328 for their remarkable behavior with hydroxylamine and phenylhydrazine. Acetyl-acetone, CH 3 . CO . CH 2 . CO . CH 3 , boils at 137. See above for its formation. It can be produced by electrolyzing an alcoholic solution of sodium acetyl acetone. Tetraacetylethane is formed by the action of iodine upon the same salt (B. 26, R. 884). S 2 C1 2 and SC1 2 produce dithio- and monothio-acetyl acetone (B. 27, R. 401, 789). See p. 328 for the action of hydrazine and phenyl- hydrazine. Copper Acetyl Acetone, (C 5 H 7 O 2 ) 2 Cu. Beryllium Acetyl Acetone (C 5 H ? - O 2 ) 2 Be, melts at 108 and boils at 270. Aluminium Acetyl Acetone, (C 5 H 7 O 2 ) 3 A1, melts at 193 and boils at 314. The vapor densities of these bodies indicate the bivalent nature of ^lucinum, and the trivalent character of aluminium (Combes, B. 28, R. 10). Octochloracetyl Acetone melts at 43. Octobromacetyl Acetone, CBr 3 . COC- Br 2 COCBr s , is formed when chlorine or bromine acts upon phloroglucin. It melts at "154 (B. 23, 1717). Alkylized acetyl acetones are produced when sodium and alkyl iodides act upon acetyl acetone (Combes, B. 20, R. 285 ; 21, R. u). 324 ORGANIC CHEMISTRY. Acetyl-methylethyl Ketone, CH 3 . CO . CH 2 . CO . C 2 H 5 , acetylpropionyl methane, boils at 158. Acetyl-methylpropyl Ketone, acetyl-butyryl methane, boils at 175 (B. 22, 1015). (3) Y- or i-4-Diketones. These correspond to the paraquinones of the aromatic series (see these). They are not capable of forming salts, hence are not soluble in the alkalies. They form mono- and di-oximes with hydroxylamine, and mono- and di-hydrazones with phenylhydrazine; these are color- less. The readiness with which the f-diketones form pyrrol, furfurane, and thiophene derivatives is characteristic of them. Acetonyl Acetone, s Diacetylethane, [2.5-Hexandion], CH 3 .- CO . CH 2 . CH 2 . CO . CH 3 , is obtained from pyrotritartaric^ acid, C 7 H 8 O 3 (see this), and from acetonyl acetoacetic ester (see this), upon heating to 160 with water (B. 18, 58), and from isopyrotritartaric acid and diacetylsuccinic ester, when they are allowed to stand in contact with sodium hydroxide (B. 22, 2100). A liquid with an agreeable odor. It is miscible with water, alcohol, and ether. It boils at 194 C. Conversion of Acetonyl Acetone into i.4-Dimethyl-furfurane, -thio- phene, and -pyrrol (Paal, B. 18, 58, 367, 2251). (i) The direct removal of one molecule of water from acetonyl acetone (by distillation with zinc chloride or P 2 O 5 ) affords dimethyl furfurane (B. 20, 1085) : f~*T-T CH 2 . CO . CH 3 CH = C/ 3 Dimethyl Furfurane. Other p-diketone compounds react in a similar manner (Knorr, B. 17, 275 6 )- (2) When heated with phosphorus sulphide acetonyl acetone yields dimethyl thiophene : CH 2 .CO.CH 3 CH = C/ 3 Dimethyl Thiophene. All the Y diketones or (i.4)-dicarboxyl compounds, e. g., the ^-ketonic acids (see these), yield the corresponding thiophene derivatives upon like treatment (B. 19, 551). (3) Dimethyl pyrrol is produced on heating acetonyl acetone with alcoholic ammonia : CH 2 . CO . CH 3 _ CH = C< , 2H . O CH 2 . CO . CH 3 + ^ ^ CH - C CH Dimethyl Pyrrol. DIKETONES. 325 All compounds containing two CO-groups in the (1.4) position react similarly with ammonia and amines. Such are diaceto-succinic ester and laevulinic ester. All the pyrrol derivatives formed as above, when boiled with dilute mineral acids, have the power of coloring a pine chip an intense red. This reaction is, therefore, a means of recognizing all (i.4)-diketone compounds (B. 19, 46). These deriva- tives react similarly with amidophenols and amido-acids (B. 19, 558). In all these conversions of acetonyl acetone into pyrrol, thiophene, and furfurane derivatives it may be assumed that it first passes from the diketone form into the pseudo-form of the unsaturated diglycol (P. 57): CH ! CH 3 and from this, by replacing the 2OH groups with S, O, or NH, the corresponding furfurane, thiophene, and pyrrol compounds are pro- duced (B. 19, 551). 1.5- or J-Diketones are not known. If it is attempted to prepare them from the 6-diketone dicarboxylic esters, e. g., ao-diacetyl glutaric ester: resulting from the condensation of aldehydes and acetoacetic esters, by splitting off carboxyethyl groups, there results instead of, for example, diacetylpropane or 2.5- heptandion, CH 3 . CO . CH 2 . CH 2 . CH 2 . CO . CH 3 , a carbocyclic condensation pro- duct 3-Methyl-A 2 -R-hexene (A. 288, 321). C- Diketone (1.7). Diacetyl Pentane, CH 3 . CO(CH 2 ) 5 CO. CH 3 , belongs to this class. When this is reduced, it sustains an intramolecular pinacone formation and becomes dimethyldihydroxyheptamethylene, CH 3 . C(OH)(CH 2 ) 5 C(OH)CH 3 (B. 23, R. 249; 24, R. 634; 26, R. 316). NITROGEN-CONTAINING DERIVATIVES OF THE DIALDEHYDES, ALDE- HYDE KETONES, AND DIKETONES. 1. For the action of ammonia upon glyoxal and acetonyl acetone, consult pp. 321, 324- 2. Oximes. A. Monoximes. (a] Aldoximes of the a-aldehyde ketones and monoximes of tJie n-dikitones : isonitrosoketones or oximido-ketones. These bodies are formed (\a) by the action of nitrogen trioxide upon ketones (B. 20, 639). (i) When amyl nitrite in the presence of sodium ethylate or hydrochloric acid acts upon ketones. At times sodium ethylate and again hydrochloric acid gives the best yield (B. 20, 2194 ; 28, 1915) : CM 3 . CO . CII 3 + NO . O . C 5 H n = CH 3 . CO . CH(N . OH) -f C 5 H U . OH. An excess of amyl nitrite decomposes the oximido-body, in that the oximido-group is replaced by oxygen, with the production of a-diketo-derivatives (B. 22, 527). (2) Just as acetone is formed from acetoacetic ester, so can isonitroso- or oximido- 326 ORGANIC CHEMISTRY. acetone be prepared from the oximido-derivative of acetoacetic ester (B. 15, 1326). Nitrous acid decomposes acetoacetic acid into oximido-acetone and carbon dioxide : CH 3 . CO . CH 2 . CO 2 H -f NO . OH = CH 3 . COCH(N . OH) -f CO 2 -f H 2 O. Similarly, the oximido-compounds of the higher acetones can be directly derived from the monoalkylic acetoacetic acids and their esters by the exit of carbon dioxide (B. 20,531): CO . H + NO . OH = CH 3 . CO . C/ -f CO 2 + H 2 O, while the dialkylic acetoacetic acids do not react (B. 15, 3067). Properties. The isonitroso- or oximido-ketones are colorless, crystalline bodies, easily soluble in alcohol, ether and chloroform, but usually more sparingly soluble in water. They dissolve in the alkalies, the hydrogen of the hydroxyl group being replaced by metal, with the formation of salts having an intensely yellow color. They yield a yellow coloration with phenol and sulphuric acid, and not the blue coloration of the nitroso-reaction (B. 15, 1529). Deportment. (i) As in the keton-oximes, so also in the isonitroso-ketones, the oximido-group can be split off and be replaced by oxygen, which will lead to the formation of diketo bodies, CO . CO . Sodium bisulphite, and boiling the result- ing imidsulphonic acid with dilute acids will bring about this transposition (B. 20, 3162). The reaction also takes place when isonitroso-ketones are boiled directly with dilute sulphuric acid (B. 20, 3213). The decomposition is sometimes more readily effected by nitrous acid (B. 22, 532). (2) The aldoximido-ketones, like the aldoximes (p. 206), are converted by dehy- drating agents e. g. , acetic anhydride into acidyl cyanides or a-keton-carboxylic nitriles (see these) (B. 20, 2196). (3) Amido-ketones (p. 319) are produced in the reduction of isonitroso-ketones by means of stannous chloride. (4) Two molecules of phenylhydrazine acting upon the isonitroso-ketones produce osazones, e.g., CH 3 . C(N 2 H . C 6 H 5 )CH(N 2 H . C 6 H 5 )-acetonosazone (B. 22, 528). (5) By the further action of hydroxylamine or its hydrochloride (B. 16, 182) upon isonitroso-acetone, the ketone oxygen is replaced and ketoximic acids or dioxinies of the a-aldehyde ketones and o-diketones are produced. (6) The benzyl ether results from the action of sodium alcoholate and benzyl chloride upon nitroso-acetone. This is isomeric with the benzyl-isonitroso-acetone derived from benzyl-aceto-acetic acid : C 7 H 7 CH, . CO . CH : N . OC,H, and CH 3 . CO . C< ^N.OH. Isonitroso-acetone-benzyl Ether Benzyl-isonitroso-acetone. This is evidence that the oximide group, N.OH, is present in the isonitroso- compounds (B. 15, 3073). Consult B. 16, 835, for the salts of the isonitroso-ketones. Isonitroso-acetone, aldoxime of pyroracemic aldehyde, CH 3 .- CO.CH: (N . OH), is very readily soluble in water; crystallizes in silvery, glistening tablets or prisms; fuses at 65, and decomposes at higher temperatures, but may be volatilized in a current of steam. The aldehyde of pyroracemic acid, CH 3 . CO. CHO (p. 296), can be obtained from it by splitting off the isonitroso-group. Monoximes of the a-Diketones. Isonitrosomethyl-acetone, CH 3 .CO.C = NOH.CHg, melts at 74 and boils at 185-188. honitrosomethylpropyl-ketone, CH 3 CO . C = NOH . CH 2 . CH 3 , melts at 52-53 and boils at 183-187. Isonitroso- DIKETONES. 327 diethyl-kctone, C 2 H 5 . CO . C = N . OH . CH 3 , melts at 59-62. Isonitrosomethyl- butyl-ketone, CH 3 . CO . C= NOH . C 3 H 7 , melts at 49.5. honitrosomethyl-is bitty f- ketotie, CH 3 .CO . C = NOH . CH(CH 3 ) 2 , melts at 75. Isonitrosomcthyl-isoamyl- ketone, CH 3 . CO . C= NOH . CH 2 . CH(CH 3 ) 2 , melts at 42 C. honitrosomethyl- isocapryl-ketone, CH 3 . CO . C = NOH . CH 2 . CH 2 . CH(CH 3 ) 2 , melts at 38. B. Oxime-anhydrides of the /3-Diketones or Isoxazoles. Monoximes of the /3-formylketones and of the /3-diketones are not known. In the attempt to prepare them water splits off and an intramolecular anhydride formation takes place. The oxime-anhydrides are isomeric with the oxazoles, which also con- sist of five members; hence their name, isoxazoles (B. 21, 2178 ; 24, 390; 25, 1787). a-Methylisoxazole, CH 3 -a-C 3 H 2 NO, boiling at 122, and y-methylisoxazole, CH 3 -y-C 3 H 2 NO, boiling at 118, result from oxymethylene or formyl acetone. They are transparent liquids, having an intense odor, resembling that of pyridine. a-Methylisoxazole readily rearranges itself into cyanacetone (see this): CH=CHOH CH CH CH CO . CH 3 CH C.CH 3 I ^- || y II II > II y II CH 3 . CO NH 2 -H 2 CH 3 C a N CH . OH NH 2 -HO CH a N ay-Dimethylisoxazole (CH 3 ) 2 -ay-C 3 HNO, boiling at 141-142, has a very peculiar odor, and is obtained from acetylacetone and hydroxylainine hydrochloride. C. Dioximes. (a) Glyoximes or a-Dioximes. The monoxime of glyoxal is not known, but when it (pyroracemic aldehyde) and the a-diketones are treated with hydroxylamine hydrochloride, then the a-dioximes or glyoximes are formed. They can also be obtained from a-isonitroso-ketones or a-dichlorketones. Glyoxime, CH(=N . OH) . CH(=N . OH), melting at 178 (B. 17,2001; 25, 705 ; 28, R. 620), is prepared from trichlorlactic acid (p. 340). Methyl Glyoxime, Acetoximic Acid, CH 3 C(NOH) . CH(NOH), melts at 153. Dimethyl Glyox- ime, Diacetyldioxime, CH 3 C(NOH) . C(NOH)CH 3 , melts at 234 (B. 28, R. 1006). Methyl-ethyl Glyoxime, CH 3 C(NOH). C(NOH) . C 2 H 5 , melts with decomposition at 170. Methyl-propyl Glyoxime melts at 168. Methyl-isobutyl Glyoxime melts at 170-172. (b\ Glyoxime Peroxides (B. 23, 3496) result when NO 2 acts upon an ethereal CH 3 . C = N O solution of the glyoximes : dimethyl glyoxime peroxide, i I , boils at ^>1A^ . V-x JN \J 222-223. Methyl-ethyl Glyoxime Peroxide boils at 115-116 (16.5 mm.). (c) Furazanes, Azoxazoles, Furo-tsL.&^-diazoles are the anhydrides obtained from CFT N certain a-dioximes. Furazane, i ^O* itself is not known, while dimethyl- furazane, for example, from diacetyl dioxime, has been prepared. (d) /3-Dioximes are not known (see above) ; they would be oxime anhydrides of the ft -diketones or isoxazoles. (e) y-Dioximes, which may be systematically derived from the y-dialdehydes (y-butyrolactone, see this) and y-aldehyde-ketones, not known in a free condition and probably not capable of existing, as well as from known y-diketones, may be prepared (i) by the action of hydroxylamine upon pyrrol (B. 22, 1968) and alkyl pyrrols (B. 23, 1788) ; (2) from y-diketones and hydroxylamine. They are decom- posed by boiling alkalies into the corresponding acids, or y-diketones. Succinaldehyde-dioxime, HO . N : CH . CH 2 . CH 2 . CH : N . OH, melting at 173, passes upon reduction into tetramethylene diamine (p. 313). Ethyhiiccinal-dioxime, HO . N : CH . CH(C 2 H.) . CH 2 . CH : N(OH), melts at 134-135. Propionyl-pro- pional-dioxime, CH 3 . CH.C : N(OH) . CH 2 . CH ? . CH : N(OH), melts at 84-85. Methyl-lavtdinal-dioxime, CH 3 . C : N(OH) . CH 2 CH(CH 3 )CH : N(OH). Acetonyl- 328 ORGANIC CHEMISTRY. acetone-dioxime, CH 3 . C : N(OH)CH 2 . CH 2 C : N(OH) . CH 3 , melts at 134-135. uu-Diacetylpentan-dioxime, CH 3 C : N(OH)(CH 2 ) 3 C: N(OH)CH 3 , melts at 172. 3. Hydrazine and Phenylhydrazine Derivatives. Dimethylaziethane, 3 I i , melting above 270, and Dimethylbishydrazi- CH 3 C = N methylene, \ >C(CH 3 ) . C(CH 3 )< i , melting at 158, are obtained from di- acetyl and hydrazine (J. pr. Ch. [2] 44, 174). Monohydrazones. Hydrazone of Pyroracemic Aldehyde, CH 3 CO . CH : - N . NH . C 6 H 5 , melting at 148, is obtained by saponifying the reaction-product resulting from diazobenzene chloride and sodium acetoacetic ester with alcoholic caustic potash. Diacetyl-hydrazone, CH 3 . CO . C : N(NHC 6 H 5 )CH 3 , melting at 133, has been prepared from diacetyl- and methyl-acetoacetic ester (Japp and Klingemann) (A. 247, 190). Dihydrazones or Osazones. Glyoxal (p. 320), methyl-glyoxal (p. 322), the 0-diketones and the a-isonitroso-acetones, when treated with phenylhydrazine, lose two molecules of water and form: diphenyl-hydrazones or osazones, which can also be obtained from a-oxyaldehydes, a-oxyketones, a-amidoaldehydes and a-amido- ketones. The osazones have become especially important for the chemistry of the aldopentoses, and the aldo- and ketohexoses. The osazones are oxidized by potassium chromate and acetic acid to osoMrazones, which are converted by hydrochloric acid and ferric chloride into osotriazones : = N-NC 6 H 5 Fe 2 Cl 6 CH 3 C = N ^rN NC 6 H 5 HCl~^CH 3 C = N ' 6 5 iacetyl-osazone Diacetyl-osotetrazone Diacetyl-osotriazone. Glyoxal-osazone, C 6 H 5 NHN : CH . CH : N . NHC 6 H 5 , melts at 177. Glyoxal- CH:N.NC 6 H 5 osofetrazone, i i , melts at 145 (B. 17, 2001 ; 21, 2752 ; 26, 1045). Methyl-glyoxal-osazone, QH^NH . N : C(CH.) . CH : N . NHC 6 H,, melts at 145 (B. CH:N.N.C 6 H 5 26, 2203). Methyl-glyoxal-osotetrazone, \ \ , melts at io6-io7. v^-H-oV^ ^^ JNI . JNI . i^glric Methyl-glyoxal-osotriazone, \ ' >NC 6 H 5 , boils at 149-150 (60 mm.) (B. 21, v^ l~i o v^' J\ 2755). Diacetyl-osazone (formula above) melts with decomposition at 236 (B. 20, 3184; A. 249, 203). Diacetyl-osotetrazone (formula above) melts with decomposi- tion at 169. Diacefyl-osotriazone ( formula above) melts at 35 and boils at 255 (B. 21, 2759). a-Acetyl-propionyl-hydrazone, CH 3 C( : NNHC 6 H 5 )CO . C ? H 5 , from acetyl-propionyl, melts at 96-98. fi-Acetyl propionyl-hydrazonc, CH 3 . CO . C( : N- NHC 6 H 5 )C 2 H 5 , from ethyl acetoacetic acid, melts at 116-117. Acetyl-propionyl- osazone melts at 162 (B. 21, ,1414; A. 247, 221). The I.3-diketones and the 1.3-oxymethylene ketones (p. 319) unite with hydra- zine and phenylhydrazine, forming pyrazoles (see these), which may be regarded as derivatives of the i-3-olefine ketols (A. 279, 237) : e. g., oxymethylene acetone and N NH hydrazine yield 3-Methylpyrazole, I (B. 27, 954). CH 3 .C.CH:CH Acetonyl-acetone, a i.4-diketone, and phenylhydrazine yield: Acetonyl acetonosa- CH : C CH, zone, melting at 120, and phenylamido-dimethyl-pyrrol, \ >NNHC 6 H 5 , melt- CH : C CH 3 ing at 90 and boiling at 270 (B. 18, 60 ; 22, 170). a-Hydrazoximes. Methyl-glyoxal-phenyl hydrazoxime, CH 3 . C : N(NHC 6 H 5 ) . - ALCOHOL- OR OXY-AClDS. 329 CH : NOH, melting at 134, is prepared by the action of phenylhydrazine upon isonitroso-acetoacetic acid. It parts readily with water and becomes methyl-n- phenyl osotriazole, 'I > NC 6 H s ( A - 262 2 7 8 )- 7. ALCOHOL- or OXY-ACIDS, C n H 2n <^ H 2 Acids of this series show a twofold character in their entire deport- ment. Since they contain a carboxyl group, they are monobasic acids with all the attaching properties and transpositions of the latter; the OH group linked to the radical bestows upon them all the properties of the monohydric alcohols. As already indicated in the introduction to the dihydric compounds, these alcohols must be dis- tinguished as primary, secondary, and tertiary, according as they con- tain, in addition to the carboxyl group, the group CH 2 OH, char- acteristic of primary alcohols, the radical CHOH, peculiar to the secondary alcohols, or the tertiary alcohol group =C . OH. This difference manifests itself in the deportment of these bodies when subjected to oxidation. However, the manner in which the alcoholic hydroxyl group in an alcohol-acid acts upon the carboxyl group present in the same molecule depends greatly upon the position of these two groups with reference to each other. It is just this differentiating, opposing position of the two reactive groups which induces class differences of a distinctly new type, which are there- fore made prominent because the oxidations manifested by primary, secondary and tertiary alcohols are already known to us. At present they are mostly termed oxy- or hydroxy-fatty acids, because of their origin from the fatty acids by the replacement of an hydrogen atom by OH. The " Geneva names" are formed by the insertion of the syllable "ol," charac- teristic of alcohols, between the name of the hydrocarbon and the word acid : CH 2 OH . COOH, oxyacetic acid, or \ethanol acid}. Glycollic and ordinary or lactic acid of fermentation are the best known and most important representatives. General Methods of Formation. (i) Careful oxidation (a) of dipri- mary, primary secondary and primary tertiary glycols with dilute nitric acid, or platinum sponge and air : CH,OH = CH..OH + ^ . CH 3 .CH.OH = CH,CH.OH + CH 2 .OH COOH CH 2 OH COOH Glycol Glycollic Acid a-Propylene Glycol a-Lactic Acid. (b} By the oxidation of oxyaldehydes. (2) The action of nascent hydrogen (sodium amalgam, zinc and hydrochloric or sulphuric acid) upon the aldehyde acids, the ketonic 28 33 ORGANIC CHEMISTRY. acids (pyroracemic acid, CH 3 . CO . CO 2 H) and dicarboxylic acids (oxalic acid, CO 2 H . CO 2 H) : CH 3 . CO . CO 2 H -f 2H = CH 3 . CH(OH) . CO 2 H COOH . COOH + 4H = COOH . CH 2 OH -f H 2 O. This reaction has been repeatedly used in preparing /?-, y- and d-oxy-acids from (3-, f- and <5-ketone carboxylic esters. (3) Some fatty acids have OH directly introduced into them. This is accomplished by oxidizing them with KMnO 4 in alkaline solution. Only acids containing the tertiary group CH (a so-called tertiary H-atom) are adapted to this kind of transposition (R. Meyer, B. n, 1283, 1787; 12, 2238; A. 208, 60 ; 220, 56). Nitric acid effects the same as MnO 4 K (B. 14, 1782; 16, 2318). (4) By heating unsaturated fatty acids with aqueous caustic potash or soda to 100 (A. 283, 50). (5) The transposition of the monohalogen fatty acids with silver oxide, boiling alkalies, or even water. The conditions of the reaction are perfectly similar to those observed in the conversion of the alkyl- ogens into alcohols. CH 2 C1 . C0 2 H -f H 2 = CH a <** H + HC1. The tt-derivatives yield a-oxy-acids ; the /3-derivatives are occasionally changed to unsaturated acids by the splitting-off of a haloid acid, while the y-compounds form y-oxy-acids, which subsequently pass into lactones. y-Halogen acids are converted directly into lactones by the alkaline carbonates. (6) By the action of nitrous acid upon amido-acids: CH 2 (NH 2 ) . CO 2 H -f NO 2 H == CH 2 (OH) . CO 2 H + N 2 -f H 2 O. Amido-acetic Acid' Oxyacetic Acid. (7) The oxy-acids can be obtained from the diazo-fatty acids, on boiling them with water or dilute acids. (8) From the a. keton-alcohols e. g , butyroin and isovaleroin (p. 317) on treating them with alkalies and air. Nucleus-synthetic Methods of Formation. (9) By allowing hydrocy- anic acid and hydrochloric acid to act upon the aldehydes and ketones. At first oxycyanides, the nitriles of oxy-acids (see these), are produced, after which hydrochloric acid changes the cyanogen group into car- boxyl : 1 . Phase : CH 3 . CHO + NCH = CH 3 . CH<^ 2. Phase : CH 3 . CH<^ -f 2H 2 O == CH 3 . CH<** n -f NH 3 . a-Oxypropionic Acid. In preparing the oxycyanides, the aldehydes or ketones are treated with pure hy- drocyanic acid, or we can add pulverized potassium cyanide to the ethereal solution ALCOHOL- OR OXY ACIDS. 33! of the ketone, and follow it with the gradual addition of concentrated hydrochloric acid (B. 14, 1965; 15,2318). The concentrated hydrochloric acid changes the cyanides to acids, the amides of the acids being at first formed in the cold, but on boiling with more dilute acid they sustain further change to acids. Sometimes the change occurs more readily by heating with a little dilute sulphuric acid. Ethy- lene oxide behaves like acetaldehyde with prussic acid. (10) The glycol chlorhydrins (p. 302) undergo a like alteration through the action of potassium cyanide and acids : 1. Phase: CH 2 . (OH) . CH 2 C1 -f CNK = CH 2 (OH) . CH 2 . CN -f KC1, 2. Phase : CH 2 . (OH) . CH 2 CN -f 2H 2 O = CH 2 (OH) . CH 2 . CO 2 H + NH 3 . /3-Oxypropionic Acid. (n) A method of ready applicability in the synthesis of oxyacids consists in permitting zinc and alkyl iodides to act upon diethyl oxalic ester (Frankland and Duppa). This reaction is like that in the formation of tertiary alcohols from the acid chlorides by means of zinc ethyl, or of the secondary alcohols from formic esters (p. 114) i and 2 alkyl groups are introduced into one carboxyl group (A. 185, 184): ,O . C 2 H 5 Zn(CH 3 ) 2 /O . C 2 H 5 Cx. > C CH 3 ^O I \0 . ZnCH 3 C0 2 C 2 H 5 C0 2 C 2 H 5 C0 2 C 2 H 5 CO 2 C 2 H 5 Oxalic Ester Dimethyl-oxalic Ester. If we employ two alkyl iodides, two different alkyls may be intro- duced. The acids obtained, as indicated, are named in accordance with their derivation from oxalic acid, but it would be more correct to view them as derivatives of oxy- acetic acid or glycollic acid, CH 2 (OH) . CO 2 H, and designate, e. p., dimethyl-oxalic acid, as dimethyl-oxyacetic acid. (12) When sodium or sodium ethylate acts upon the acetic esters and propionic esters it converts them into /3-ketone carboxylic esters, but in the case of butyric and isobutyric esters it produces the ether esters of /3-oxy-acids, such as ethoxycaprylic ester, (CH 3 ) 2 CH . CH(OC 2 H 5 ) . C(CH 3 ) 2 . CO 2 . C 2 H 5 , from isobutyric ester (A. 249, 54)- Reactions in -which Groups are Split off. (13) The fatty acids are formed from alkyl-malonic acids, CRR / (CO 2 R) 2 , by the withdrawal of a carboxyl group (p. 241), and the oxy-fatty acids are obtained in a similar manner from alkyl oxymalonic acids or tartronic acids : CR(OH)<^ = CRH(OH) . CO 2 H -f CO 2 . Alkyl-tartronic Acid Alkyl-oxy-acetic Acid. The tartronic compounds are synthetically prepared from malonic acid esters, t. g. , CH 2 <' ( > 2 Cli 5 ' ky ^ rst i ntr ducing the alkyl group (see malonic acid), then replacing the second hydrogen of CH 2 by chlorine, and finally saponifying the alkylic monochlor-malonic ester with baryta (B. 14, 619). Isomerism. The possible cases of isomerism with the oxy-acids are most simply deduced by considering the oxy-acids as the mono-hydroxyl 33 2 ORGANIC CHEMISTRY. substitution products of the fatty acids. Then the isomerides are the same as the mono- halogen fatty acids, which may be regarded as the haloid esters of the alcoholic acids corresponding to them. Oxyacetic or glycollic acid is the only acid which can be obtained from acetic acid : CH 3 . COOH CH 2 OH . COOH Acetic Acid Glycollic Acid (p. 334). Propionic acid yields two oxypropionic acids : CH 3 . CH 2 . COOH CH 3 . CH(OH) . COOH CH 2 (OH) . CH 2 . COOH Propionic Acid a-Oxyprppionic Acid /3-Oxypropionic Acid ord. Lactic Acid (p. 335) Hydracrylic Acid (p. 341). These are distinguished as a- and /3-oxypropionic acids respectively. The a-acid contains an asymmetric carbon atom. Theoretically, it should yield an inactive variety, which can be decomposed, and two optically active modifications. These, in fact, exist. Normal butyric acid yields three and isobutyric acid two mono-carboxylic acids : CH 3 .CH 2 .CH 2 CO 2 H CH 3 .CH 2 .CH(OH).CO 2 H a-Oxybutyric Acid (p. 337) n-Butyiic Acid CH 3 .CH(OH).CH 2 .CO 2 H /3-Oxybutyric Acid (p. 342) CH 2 OH.CH 2 .CH 2 .COOH y-Oxybutyric Acid (p. 342) 2 H . . a-OxyisobutyricAcid(p. 337) obutyricAcid. HOCHp> OT ' ' ' /3-Oxyisobutyric Acid (unknown). These alcohol -acids are themselves divided into Primary acids : Glycollic acid, hydracrylic acid, y-oxybutyric acid, /3-oxyisobutyric acid. Secondary acids : a Oxypropionic acid, a-oxybutyric acid. Tertiary acids : a- Oxy isobutyric acid. Properties. The oxy- fatty acids containing one OH group are, in consequence, more readily soluble in water, and less soluble in ether than the parent acids (p. 245). They are less volatile and, as a .general thing, can not be distilled without undergoing a change. Deportment. (i) The alcohol-acids behave like the mono-carboxylic acids, in that like these they yield, through a change in the carboxyl group, normal salts, esters, amides and nitriles : COOK COOC 2 H 5 CONH 2 CN CH 2 OK CH 2 OH CH 2 OH CH 2 OH. (2) The remaining OH-group deports itself like that of the alco- hols. Alkali metals and alkyls may replace its hydrogen. Acid radicals and NO 2 are substituted for it by the action of chlorides of monobasic acid radicals (like C 2 H 3 O . Cl), and a mixture of concen- trated nitric and sulphuric acids : . C 2 H 3 O , r TT ^O . NO 2 2 H 3 and C ' H <C(OH) . C0 2 H + O = CH (6) The a-oxy- acids undergo a like decomposition when heated with dilute sulphuric or hydrochloric acid (or by action of concentrated H 2 SO 4 ). Their carboxyl group is removed as formic acid (when concentrated H 2 SO 4 is employed, CO and H 2 O are the products) : (CH,) 2 C(OH) . CO 2 H = (CH 3 ) 2 CO -f HCO 2 H CH 3 . CH(OH) . CO 2 H = CH 3 . CHO + HCO 2 H. Another alteration is sustained by the a-oxy-acids at the same time ; it, however, 334 ORGANIC CHEMISTRY. does not extend far. Water is eliminated and unsaturated acids are produced. This change is easily effected when PC1 3 is allowed to act on the esters of a-oxy- acids (p. 277). (7) Especially interesting is the deportment of the a-, /?-, y,- or 6 oxy-acids in respect to the exit of water from carboxyl and alcoholic hydroxyl groups. (a) The a-oxy-acids lose water when they are heated and become cyclic double esters the lactides in the formation of which two molecules of the a-oxy-acid have taken part : COOH HO . CH . CH 3 CO . O . CH . CH 3 CH 3 CHOH HOCO = CH 3 CHO CO ' 2 , a-Oxypropionic Acid or Lactic Acid Lactide. (b] When the fi-oxy-acids are heated alone, water is withdrawn and unsaturated acids are the products (p. 277) : CH 2 (OH) . CH 2 . CO 2 H = CH 2 : CH . CO 2 H -f H 2 O. /3-Oxypropionic Acid Acrylic Acid. Hydracrylic Acid (^) The f- and $ oxy-acids lose water at the ordinary temperature, and change more or less completely into simple cyclic esters the y- and ( 2 ) nucleus-synthetic, from aldehydes and prussic acid, and subsequent saponification of the nitriles of the oxy-acids by means of hydrochloric acid (method 9) . (^) The tertiary oxy-acids result (1) From the oxidation of dialkyl-acetic acid (general method 3). (2) Upon treating a-ketone alcohols with alkalies and air (method 8, p. 330). (3) By the action of prussic acid and hydrochloric acid upon ketones (method 9)- (4) When zinc and alkyl iodides react with oxalic ester (method II, p. 331). Oxybutyric Acids. Four of the five possible isomerides are known; two of these are a-oxy-acids : (i) a-Oxybutyric Acid, CH 3 . CH 2 . CH(OH)CO 2 H, melting at 43, has been resolved by brucine into its optically active components (B. 28, R. 278, 325, 725). (2) a-Oxyisobutyric Acid, Butyl-lactinic Acid, Acetonic Acid, Dimethyl-oxalic Acid [2-Methyl-2-propanol Acid], (CH 3 ^ 2 C(OH)COOH, melting at 79 and boiling at 212, is obtained from dimethyl-acetic acid, from acetone and from oxalic ester (see above) ; hence the names acetonic acid and dimethyl-oxalic acid. It is produced when /3-isoamylene glycol is oxidized by nitric acid, and is obtained from a-brom- and a-amidobutyric acid, as well as from acetone chloroform. Acetone Chloroform, (CH 3 ) 2 CC(OH) . CO 2 H (A. 204, 18). Oxycaproic Acids, C 6 H 12 O 3 = C 5 Hio( OH ) . CO 2 H. a-Oxycaproic Acid, CH 3 . (CH 2 ) 3 . CH (OH) . CO 2 H, is probably the so-called leucic acid, obtained from leucine by the action of nitrous acid. It melts at 73 (Strecker, 1848). a-Oxyisobutyl-acetic Acid, (CH 3 ) 2 CH . CH 2 CH(OH)CO 2 H, melting at 54, is obtained from inactive a-amidoisobutyl-acetic acid, or isoleucine (B. 26, 56). a-Oxy- diethy I- acetic Acid, Diethyl-oxalic Acid, (C 2 H 5 ) 2 C(OH)CO 2 H, melts at 80 (A. 200, 21). a-Oxytertiary-butyl-acetic Acid, (CH 3 ) 3 C . CH(OHjCO 2 H, by the reduction of trimethyl-pyroracemic acid, melts at 87 (see this). 29 338 ORGANIC CHEMISTRY. a-Oxycaprylic Acids, a-Oxy-n-caprylic Acid, CH 3 (CH 2 ) 5 CH(OH)CO 2 H, from cenanthol, melts at 69.5. Di-n-propyl Glycollic Acid, a-Oxy-di-n-propyl-acetic Acid, (C 3 H 7 ) 2 C(OH) .CO 2 H, from butyroin (p. 317), melts at 72 (B. 24, 1273). Di-isopropyl Oxalic Acid, a-Oxy-di-isopropyl-acetic Acid,(C 3 H 7 ) 2 C(OH)CO 2 H, melts at in (B. 28, 2463). Di-isobutyl Glycollic Acid (C 4 H 9 ) 2 C(OH)CO 2 H, melts at 114. a-Brom-fatty acids have yielded the following: a-oxymyristic acid, C 13 H 26 (OH) .- CO 2 H, melting at 51 (B. 22, 1747); a-Oxypalmitic Acid, C 15 H 30 (OH)CO 2 H, melting at 82 (B. 24, 939) ; a-Oxystearic Acid, C 17 H 34 (OH)CO 2 H, melting at 84-86 (B. 24, 2388). In the following pages those a-oxy-acid derivatives will be described which belong to glycollic and lactic acids. Alkyl Derivatives of the a-Oxy-acids. A single a-oxy-acid yields three kinds of alkyl derivatives : ethers, esters and ether-esters : COOH COOH COOC 2 H 5 COOC 2 H 5 CH 2 OH CH 2 .O.C 2 H 5 CH 2 OH CH 2 .O.C 2 H 5 . Glycollic Ethyl Glycollic Glycollic Ethyl Ethyl Glycollic Acid Acid Ester Ethyl Ester. (1) The alkyl ethers of the a-oxy-acids are obtained (l) by the action of sodium alcoholates upon salts of the a-halogen substitution products of the fatty acids ; (2) by the saponification of the dialkyl-ether esters of the a-oxy-acids. Methyl-ether Glycollic Acid, CH 3 OCH 2 COOH, boils at 198. Ethyl Glycollic Acid boils at 206-207. a-Ethoxyl-propionic Acid, CH 3 CH(OC 2 H 5 ) . CO 2 H, boils with partial decomposition from 195-198. (2) Alkyl Esters of the a-oxy-acids result (l) on heating the free acids with abso- lute alcohol; (2) when the cyclic double esters, the lactides, are heated with alcohols. Glycollic Methyl Ester, CH 2 (OH)COOCH 3 , boils at 151. Glycollic Ethyl Ester boils at 160. Lactic Methyl Ester, CH 3 CH(OH)CO 2 CH 3 , boils at 145. Lactic Ethyl Ester boils at 154.5. (3) The dialkyl-ether esters of the a-oxy-acids are produced (l) when sodium alco- holates act upon the esters of a-halogen fatty acids ; (2) by the interaction of alkyl- ogens and the sodium derivatives of the alkyl esters of the a-oxy-acids. Methyl Glycollic Methyl Ester, CH 2 (OCH 3 ) . COOCH 3 , boils at 127. Ethyl Ester boils at 131. Ethyl Glycollic Methyl Ester, CH 2 (O. C 2 H 5 )CO . OCH 3 , boils at 148. Ethyl Glycollic Ethyl Ester boils at 152 (B. 17, 486). Methyl Lactic Methyl Ester, CH 3 - CH(OCH 3 )COOCH 3 , boils at 135-138. Ethyl ester boils at 135.5. Ethyl Lactic Ethyl Ester, CH 3 . CH(OC 2 H 5 ) . COOC 2 H 5 , boils at 155 (A. 197, 21). Anhydride Formation of the a-Oxy-acids. The ethers of the alcohols may be considered as their anhydrides, for they sustain the same relation to the alcohols as the anhydrides of the mono-carboxylic acids bear to the latter. When in the an- hydride formation one molecule of an alcohol and a molecule of a carboxylic acid combine, the product is an ester. As the a-alcohol acids exhibit both the character of a carboxylic acid and that of an alcohol, it is possible to have all these varieties of anhydride forma- tions occurring with an a-oxy-acid. Glycollic acid has been most thoroughly studied in this direction. ANHYDRIDES. LACTIDES. 339 Ia O GI y collic anhydride is not known. 3- O<^S 2 ro> Alcohol- and acid-anhydride of glycollic acid : Diglycollic Anhydride. 4< HO co 2< cH. > Open ester acid : Gly lcoll -s l y ' collic Acid - 5- O O Closed > C 7 clic double ester of glycollic acid: Glycollide, simplest Lactide. Diglycollic Acid, C 4 H 6 O 5 , the alcohol anhydride of glycollic acid is formed on boiling monochloracetic acid with lime, baryta, magnesia, or lead oxide (also with glycollic acid), and in the oxidation of diethylene glycol, O<^ 2 ' ^ 2 ' Q^ (p. 295). Diglycollic acid crystallizes with water in large rhombic prisms, which melt at 148. /-'FT r*r\ Diglycollic Anhydride, OO, melting at 86, is produced when polyglycollide is distilled under greatly reduced pressure. When heated at the ordinary pressure, or if preserved, it reverts to polyglycollide, from which it differs by its lower melting point and ready solubility in chloroform. It combines readily with water (A. 279, 45)- Polyglycollide, (C 2 H 2 O 2 )x, melting at 223, is formed on heating glycollic acid, and when dry sodium chloracetate is heated alone to 150. It passes into glycollic esters when heated with alcohols in sealed tubes (A. 279, 45). Lactide, o CH 2 , boils at 153 (B. 28, R. 180). CH-CHO COO Lactic Ethidene Ester, i >CH . CH 3 , boiling at 151, is produced when lactic acid and acetaldehyde are heated to 160. Its hexachlor-derivative is chloralide (p. 340). Acid Esters of the a-Oxyacids (pp. 144, 300). Nitric Lactic Ester, Nitrolactic acid, CH 3 . CHO(NO 2 ) . COOH, is a yellow liquid, decomposing at the ordinary temperature into oxalic and prussic acids (B. 12, 1837). 340 ORGANIC CHEMISTRY. Acetyl Glycollic Add, CH 2 O(COCH 3 )COOH, is obtained from glycollic acid and acetic anhydride. The ethyl ester, CH 2 O(COCH 3 )COOC 2 H 5 , boils at 179. Acetyl Lactic Acid, CH 3 CH(OCOCH 3 )COOH, is present in beef extract (B. 22, 2713). The ethyl ester, CH 3 . CH(OCOCH 3 )COOC 2 H 5 , boils at 177. Halogen a-Oxyacids. /5-Monohalogen Ethidene Lactic Acids. $-Chlorlactic Acid, CH 2 C1 . CH- (OH).CO 2 H, melts at 78. fi-Bromlactic Acid, CH 2 Br. CHOH . CO 2 H, melts at 89. $-IodolacticAcid, CH 2 I . CH(OH)CO 2 H, melts at 100. These three acids have been prepared by adding hydrogen chloride, bromide or iodide to epihydrinic or glycidic acid, (tH 2 CH(o')C0 2 H. /3-Chlorlactic acid is also formed from monochloraldehyde by the action of hydro- cyanic acid and by the oxidation of epichlorhydrin, CH 2 CH(O)CH 2 C1, and a-chlor- hydrin, CH 2 C1 . CH(OH) . CH 2 . OH, with concentrated HNO 3 ; as well as by the addition of hypochlorous acid to acrylic acid (together with a-chlorhydracrylic acid). Silver oxide converts it into glyceric acid ; when reduced with hydriodic acid it becomes /3-iodpropionic acid. Heated with alcoholic potash it is again changed to epihydrinic acid (see above), just as ethylene oxide is obtained from glycolchlor- hydrin (p. 298). Higher halogen substitution products of the a-oxyacids have been prepared by the gradual treatment of halogen aldehydes, like dichlor- aldehyde, chloral, bromal, and trichlorbutyric aldehyde with hydro- cyanic acid and hydrochloric acid. Trichlorlactic acid has been the most thoroughly studied. /3-Dichlorlactic Acid, CHC1 2 . CH(OH) . CO 2 H, melts at 77. /?-Trichlorlactic Acid, CC1 3 . CH(OH) . CO 2 H, melts at 105- 110, and is soluble in water, alcohol and ether. Alkalies easily change it to chloral, chloroform and formic acid. Zinc and hydrochloric acid reduce it to dichlor- and mono-chloracrylic acids (p. 281). Its ethyl ester melts at 66-67, and boils at 235. The best method of preparing it consists in heating chloralcyanhydrin with alcohol and sulphuric acid or HC1 (B. 18, 754). Because trichlorlactic acid yields chloral without difficulty, it is converted quite readily, by different reactions, into derivatives of chloral and glyoxal. It forms glyoximes with hydroxylamine, and glycosin with ammonia (p. 321, and B. 17, 1997). Chloralide, Tricklorethidene-trichlorlactic Ester, CC^.CH^ >CH . CC1 3 , was first prepared by heating chloral with fuming sulphuric acid to 105, and subsequently when trichlorlactic acid was heated to 150 with excess of chloral. It melts at. 114 and boils at 272. When heated to 140 with alcohol, it breaks up into trichlor- lactic ester and chloral alcoholate (Wallach, A. 193, i). Chloral also unites with lactic and other oxyacids, like glycollic, malic, salicylic, etc., forming the so-called chloralides (A. 193, l). Perchlorethidene-trichlorlactic Ester, CC1 3 CH< C ^>CC1 . CC1 3 , boiling at 276, is obtained by the action of PC1 5 upon chloralide (A. 253, 121). Tribromlactic Acid, CBr 3 . CH(OH) . CO 2 H, melts at I4i-i43 and unites with chloral and bromal to corresponding chloralides and bromalides. HYDRACRYLIC ACID. 34* Trichlorvalerolactinic Acid, CH 3 . CCl a . CHCl.CH(OH) . CO. 2 H, melts at 140 (\. 179 99). /9-Oxycarboxylic Acids. Generally the /3-oxycarboxylic acids, when heated, part with water and become unsaturated olefine carboxylic acids : CH 2 OH . CH 2 . C0 2 H - ~ H2 > CH 2 = CHCO 2 H Ethylene Lactic Acid or Hydracrylic Acid Acrylic Acid. In the case of the higher homologues of ethylene lactic acid, when water is eliminated, both a/9- and /fy-olefine carboxylic acids (B. 26, 2079) result. The o.-dialkyl-$ oxybutyric acids, resulting from the reduction of dialkyl acetoacetic esters, decompose with difficulty on the application of heat : the products being aldehyde and dialkyl acetic acids : CH 3 CH(OH)CButanol Acid], CH 3 . CH(OH) . CH 2 . CO 2 H (compare p. 332 for the isomerism), is formed by the action of sodium amalgam upon aceto- acetic ester (see this), by the oxidation of aldol (p. 321) with silver oxide, and from a-propylene chlorhydrin, CH 3 . CH(OH) . CH 2 C1, by the action of CNK and subsequent saponification of the cyanide. It is a thick, non-crystallizable syrup, which volatilizes with steam. When heated the acid decomposes (like all /3-oxy-acids, p. 334) into water and crotonic acid, CH 3 . CH : CH . CO 2 H. An opti- cally active /3-oxybutyric acid has been isolated from diabetic urine (B. 18, R. 451). R-Oxyisobutyric Acid, HOCH,^ /-TT/^/-\ TT L i CH 2 >CHCO 2 H, is not known. $-Oxy-n-valeric Acid, CH 3 3 CH 2 . CH(OH) . CH 2 . CO 2 H (A. 283, 74, 94). a-Methyl-$-oxybutyric Acid, CH 3 .CH(OH) . CH(CH 3 ) . CO 2 H (A. 250, 244). $-Oxyisovaleric Acid, (CH 3 ) 2 C(OH)CH 2 . CO 2 H, results when isobutyl formic acid is oxidized with KMnO 4 (A. 200, 273). $-Oxy-n-Caproic Acid, CH 3 . CH 2 . CH 2 . CH(OH)CH 2 CO 2 H, is formed on boil- ing hydrosorbic acid with caustic soda (A. 283, 124). a-Ethyl-fi-oxybutyric Acid, CH 3 .CH(OH).CH(C 2 H 5 ).CO 2 H (A. 188, 240). a-Methyl-B-oxyvaleric Acid, CH 3 . CH 2 CH(OH)CH(CH 3 ). C0 2 H (B. 20, 1321). p-Oxyisocaproic Acid, (CH 3 ) 2 CH . CH(OH) . CH 2 . CO 2 H (B. 29, R. 667). p-Oxyisoheptylic Acid, (CH 3 ) 2 CH . CH 2 . CH(OH) . CH 2 . CO 2 H, melts at 64 (A. 283, 143). fi-Methyl-propyl-ethylene Lactic Acid, (CH 3 ) (C 3 H 7 )C(OH)CH 2 CO 2 H, is produced in the oxidation of methyl allyl propyl carbinol ( J. pr. Ch. [2] 23, 267). ' H, >1 (J. pr. Ch. [2] 23,201) (i )H) . C(CH 3 )(C 2 H 5 )CO 2 H (A i 3 ) 2 C(OH)C(CH 3 ) 2 CO 2 H, melti yields CO 2 and dimethyl isopropyl carbinol when heated. fi-Oxyisoctylic Acid, (CH 3 ) 2 CH . CH 2 . CH 2 CH(OH)CH 2 C0 2 H, melts at 36 (A. 283, 287). $-Diethyl-ethylene Lactic Acid, (C 2 H 5 ) 2 C(OH)CH 2 CO 2 H, results from the oxida- tion of diethyl -allyl carbinol (J. pr. Ch. [2] 23,201) (p. 132). a-Methyl-ethyl-fi- oxybutyric Acid, CH 3 CH(OH) . C(CH 3 )(C 2 H 5 )CO 2 H (A. 188, 266). Tetramethyl- ethylene Lactic Acid, (CH 3 ) 2 C(OH)C(CH 3 ) 2 CO 2 H, melting at 152 (B. 28, 2839), ^nV^V/,CH 3 .CH(OH).C(CH 3 )(C 3 H 7 )C0 2 H(A. 226, 288). a-Diethyl-^-oxybutyric Acid, CH 3 CH(OH)C(C 2 H 5 ) 2 CO 2 H (A. 201, 65 ; 266, 98). a-Dimethyl-fi-isopropyl-ethylene Lactic Acid, (CH 3 ) 2 CH . CH(OH) . C(CH 3 ) 2 .- CO 2 H, melts at 92 (B. 28, 2843). The f- and <5-Oxyacids and their Cyclic Esters, the y- and <5-Lactones. The y- and d-oxyacids are distinguished from the a- and /3-oxyacids ,by the fact mentioned (p. 334) that they are capable of forming simple cyclic esters, when the carboxyl group enters into reaction with the alcoholic hydroxyl group. This is a reaction that is accelerated by mineral acids in the case of the formation of the ordinary fatty acid esters. The cyclic esters of the f- and <5-oxyacids are called f-Lactones and d Lactones. In the first we have a chain of four, in the second a chain of five carbon atoms closed by oxygen. They sustain the same relation to the oxides of the Y~ and <5-glycols, and to the anhydrides of the Y- and S-dicarbonic acids, that the open carboxylic esters bear to the ethers of the alcohols and fatty acid anhydrides. Suppose, for example, that a hydrogen atom has been removed from each methyl group in the formulas of ethyl ether, acetic ethyl ester and acetic anhydride, and the methylene residues are then joined to each other, we then arrive at the formulas LACTONES. 343 of tetramethylene oxide, ^-butyrolactone and succinic anhydride. The following scheme represents these relations : CH 3 .CH Q CH 3 CO , Q CH 3 CO Q CH 3 . CH 2 ^ CH 3 . CH 2 > CH 3 CO> Elhyl Ether Acetic Ethyl Ester Acetic Anhydride CH 2 .CH 2 aCH 2 CO CH 2 CO CH 2 . CH 2 > /3CH 2 CH 2 y' > CI^CO^ Tetramethyleiie Oxide y-Butyrolactone Succinic Anhydride. This lactone formation occurs more or less easily, depending upon the constitution of the ^-oxyacids. The very same causes which influence the anhydride formation with saturated and unsaturated dicarboxylic acids (see these), exert their power with the ^-oxyacids. It has been seen " that increasing magnitude or number of hydrocarbon residues in the carbon chains closed by oxygen favors the intramo- lecular splitting-off of water with the ^-oxyacids" (B. 24, 1237). When the f-oxyacids are separated from their salts by mineral acids they break down, especially on warming, almost immediately into water and lactones. It is only when the latter are boiled with alkaline carbonates that they are converted into salts of the oxyacids. This is more readily accomplished through the agency of the caustic alkalies. The 7"-lactones are characterized by great stability. They are partially converted into oxy-acids by water, but this only occurs after pro- tracted boiling, whereas those of the d- variety gradually absorb water at the ordinary temperature and soon react acid (B. 16, 373). History. The first (1873) discovered aliphatic lactone was butyrolactone, obtained by Saytzeff, who, however, regarded it as the dialdehyde of succinic acid. Erlen- meyer, Sr. (1880), expressed the opinion that lactones could only exist when they contained the group C C C COO, which is present, as is well known, in the anhydrides of succinic acid (B. 13, 305). Almost immediately afterwards J. Bredt demonstrated that isocaprolactone, from pyroterebic acid, was in fact a y-lactone (B. 13, 748). Fittig, as the result of a series of excellent investigations, established the genetic relations of the lactones to the oxyacids and unsaturated acids, and taught how this class of bodies could be produced by new methods. E. Fischer has shown that polyoxylactones play an especially important role in the synthesis of the various varieties of sugar. The following methods answer for the formation of the f-oxycar- boxylic acids and their cyclic esters the f -lactones : (1) By the reduction of the f-ketone carboxylic acids with sodium amalgam : CH 3 . CO . CH 2 . CH 2 . COOH + 2H = CH 3 . CH(OH) . CH 2 . CH 2 . CO 2 H Lsevulinic Acid y-Oxyvaleric Acid. (2) From the y -halogen fatty acids: (a) by distillation, when the lactones are immediately produced : C1CH 2 . CH 2 . CH 2 CO 2 H - - CH 2 CH 2 CH 2 COO -f HC1 ; by boiling them with water, or with caustic alkalies, or alkaline 344 ORGANIC CHEMISTRY. carbonates. In the latter case ^-lactones are even produced in the cold. (3) From unsaturated acids in which the double union occurs in the fr- or ^-position, and from the Afr- or J^-unsaturated acids : (#) by distillation ; () by digesting them with hydrobromic acid, when an addition and separation of hydrogen bromide occur ; (V) by digesting them with dilute sulphuric acid (B. 16, 373; 18, R. 229; 29, 1857): CH 2 = CHCH 2 CH 2 CO 2 H - ^ CH 3 . CH . CH 2 . CH 2 CC6 Allyl Acetic Acid y-Valerolactone. (4) By the distillation of y-lactone carboxylic acids (splitting-off of CO 2 and the formation of /-lactones), whereby the isomeric unsaturated acids are also produced (pp. 278, 284) : CH 3 > CH(COOH) . CH 2 COO Terebic Acid Isocaprolactone. The following reactions have been applied in special instances : (5) The reduction of the chlorides and anhydrides of dibasic acids e.g., the production of y-butyrolactone from succinyl chloride and from succinic anhydride (B. 29, 1192). (6) The decomposition of the reaction-products resulting from the action of halohydrins upon (a) Sodium acetoacetic ester, (3) Sodium malonic ester. Nucleus- synthetic Methods of Formation : (7) The action of zinc alkyls upon the chlorides of dibasic acids. (8) CNK upon y-halohydrins, and subsequent saponification of the resulting nitriles. The less known t-oxy acids have been prepared by the distillation of 5-chlorcarboxylic acids, or by the reduction of 0-ketone carboxylic acids. Nomenclature. ^-Lactones may be viewed as a-, /?-, and f-alkyl substitution products of butyrolactone, and may be named accord- ingly ; thus, /-methyl butyrolactone for valerolactone : CH 2 .CO CH 2 .CO >0 CH 8 . CH, CH 2 . CH CH 3 . Y ft y The "Geneva names" terminate in " olid " ; thus, butyrolactone = \_Butanolid] ; valerolactone = \\.\-pentanotid~\. Properties of the f- and 5-Lactones. They are usually liquid bodies, easily soluble in water, alcohol, and ether. They show neutral reaction, possess a faintly aromatic odor, and can be distilled without decom- position. The alkaline carbonates precipitate them from their aqueous solution in the form of oils. LACTONES. 345 Deportment. (t) They are partially converted into the correspond- ing oxyacids when boiled with water. A state of equilibrium arises here, which is much influenced by the number of alcohol radicals contained in the ^-lactones. (2) The lactones are changed with difficulty by the alkaline carbonates into salts of the corresponding oxyacids (B. 25, R. 845), whereas the caustic alkalies and baryta water effect this more readily. (3) Many ^-lactones combine with the haloid acids, forming the corresponding /-halogen fatty acids; others do not do this. In the latter the lactone union is easily severed on allowing hydrochloric or hydrobromic acid to act upon the lactones in the presence of alcohol. Then the alky I ethers of the correspond- ing f-chlor- and f-brom-fatty acids are formed (B. 16, 513). (4) The y-lactones unite with ammonia, but there is no separation of water (P- 348). (5) The lactones condense under the influence of metallic sodium and sodium alcoholate. When treated with acids, an exit of water occurs, and bodies are pro- duced which consist of the combined residues of two molecules of lactone. When these condensation products are boiled with bases, oxycarboxylic acids result, which by loss of carbon dioxide pass into oxetones (see these), derivatives of dioxyketones: 2 CH 3 . CH . CH 2 . CH 2 . C0( CH,CH(OH)CH 3 -CO, CH 3 .CHO(CH 2 ) 2 C:C< co * H /'-Lactones. Butyrolactone [Butanolid], CH 2 . CH 2 . CH 2 . COO, boiling at 206, Y P a has been obtained (i) by letting sodium amalgam and glacial acetic acid act on succinyl chloride (A. 171, 261); (2) from butyrolactone carboxylic acid (see this), by the splitting-off of CO 2 (B. 16, 2592); (3) by the distillation of y chlorbutyric acid (B. 19, R. 13); (4) from oxethyl acetoacetic ester, the reaction product of ethylene chlorhydrin and acetoacetic ester by decomposing it with baryta (B. 18, R. 26) ; (5) by treating p-phenoxybutyric acid with hydrobromic acid (B. 29, R. 286). y-Valerolactone [1.4 Pentanolid], CH 3 . CH . CH 2 . CH 2 . COO, boiling at 206, 8 -y ft a. occurs in crude wood vinegar, and may be prepared (l) by the reduction of laevulinic acid, CH 3 CO . CH 2 . CH 2 . CO 2 H (A. 208, 104) ; (2) by boiling allyl acetic acid with dilute sulphuric acid; (3) when y-bromvaleric acid is boiled with water; (4) on heat- ing y-oxypropyl malonic lactone to 220 C. (A. 216, 56) ; (5) and in small quantities whenmethyl-paraconic acid, CH 3 . CH . CH(CO 2 H) . CH 2 . COO, is distilled (A. 255, 25). Dilute nitric acid oxidizes y-valerolactone to ethylene succinic acid, while HI converts it into n- valeric acid. a-Methyl butyrolactone, CH 2 . CH 2 CH(CH 3 ) . COO, boils at 201 (B. 28, 10; 29, 1194). 346 ORGANIC CHEMISTRY. Caprolactones. y-n-Caprolactone, y-ethyl butyrolactone, [i.4-Hexanolid], CH 3 . CH 2 . CH . CH 2 . CH 2 . COO, boiling at 220, is formed by the general methods 2, 3, and 4. It also appears in the reduction of gluconic acid, metasaccharic acid and galactonic acid by hydriodic acid (B. 17, 1300; 18, 642, 1555)- /3-Methyl valerolactone, J3 y - Dimethyl butyrolactone, CH 3 . CH . CHCH 3 )- CH 2 COO, boiling at 209, is obtained from /3-acetobutyric acid. a-Ethyl-butyro- lactone, CH 2 . CH 2 . CH(C 2 H 5 )COO, boiling at 215, is formed from ethoxy-ethyl i I acetoacetic ester. ay-Dimethyl-butyrolactone, CH 3 . CH . CH 2 . CH(CH 3 )COO, boil- ing at 206, is prepared from j3 aceto-isobutyric acid. Isocaprolactone, (CH 3 ) 2 C. CH 2 . CH 2 . COO, melting at 7 and boiling at 207, is produced together with pyroterebic acid in the distillation of terebic acid. (See general method 4, p. 343.) Pyroterebic acid itself passes on long boiling into isocaprolactone. It can also be obtained from isobutyric aldehyde, malonic acid, and acetic anhydride (B. 29, R. 667). Heptolactones. y-n-Heptolactone, y-n-Propylbutyrolactone, CH 3 . CH 2 . CH 2 - CHCH 2 CH 2 COO, boiling at 235, is obtained from y-bromcenanthic acid, from n-propylparaconic acid, and from dextrose-carboxylic acid, as well as from galactose carboxylic acid on treatment with hydriodic acid (B. 21, 918). y-Isopropylbutyrolac- tone, (CH 3 ) 2 CH . CHCH 2 CH 2 COO, boiling at 224, is formed, along with isoheptylic acid, from isopropylparaconic acid, a- Ethyl Valerolactone, CH 3 .- CH . CH 2 . CH(C 2 H 5 )COO, boiling at 219, is obtained from a-ethyl-/3-acetopropionic acid and from allyl ethyl acetic acid by general method 3 (B. 29, 1857). ^-Dimethyl Valerolactone, CH 3 . CH . CH 2 . C(CH 3 ) 2 COO, melting at 52 and boiling at 86 (15 mm.), may be obtained from a-dimethyl-lsevulinic acid or mesitonic acid (see this). Octolactones. y-Isobutylbutyrolactone, (CH 3 ) 2 CHCH 2 CHCH 2 CH 2 COO, is ob- tained from isobutylparaconic acid. a-Propylvalerolactone boils at 233. a-Isopro- pylvalerolactone boils at 224 ( B. 29, 1857, 2001). a-Ethyl-fi-methylvalerolactone, CH 3 CH . CH(CH 3 )CH(C 2 H 5 )COO, boiling at 226-227, is obtained from a-ethyl-/3- methylacetopropionic acid. y-Diethylbntyrolactone, C(C 2 H 5 ) 2 CH 2 CH 2 COO, boiling from 228-233, has been prepared from succinyl chloride and zinc ethide. a-Methyl- y-isobutylbutyrolactone, (CH 3 ) 2 CH . CH 2 . CH . CH 2 . CH(CH 3 ) . COO, has been obtained from a-methylisobutylparaconic acid. y-Hexylbutyrolactone, CH 3 - (CH 2 ) 5 . CHCH 2 CH 2 COO, boils at 281 C. d-Lactones. Certain aliphatic (Mactones are known. They have been prepared by the distilla- tion of the corresponding d-chlor-acids, or by the reduction of d-ketone carboxylic acids (see these) : 6- Valerolactone, CH 2 . CH 2 . CH 2 . CH 2 . COO, boils at 230 (B. 26, 2574). 6-Caprolactone, CH 3 . CH . CH 2 . CH 2 . CH 2 . COO, melts at 13 and boils at 275. y-Ethyl-capro-b-lactone, CH 3 . CHCH(C 2 H 5 )CH 2 . CH 2 COO, boils at 254-255 (A. 216, 127; 268, 117). SULPHUR DERIVATIVES OF OXY-ACIDS. 347 Sulphur Derivatives t of the Oxy-acids : Glycollic and Lactic Acids. Only the mercaptan carboxylic acids and their transposition products will be considered here. These are acids which at the same time possess the nature of a mercaptan. They are obtained as oils, with a disagreeable odor. They are miscible with water, alcohol and ether. (1) a- Mercaptan Carboxylic Acids. Thioglycollic Acid, CH 2 <^ H [Ethanthiol Acid], is obtained from mono- chloracetic acid and potassium sulphydrate, and from thiohydantom, when heated with alkalies (A. 207, 124). On adding ferric chloride to its solution, we obtain an g indigo-blue coloration. It is a dibasic acid. The barium salt, CH 2 <^Q >Ba -f- 3H 2 O, dissolves with difficulty in water. a-Thiolactic Acid, CH 3 . CH(SH)CO 2 H, is obtained from pyroracemic acid and hydrogen sulphide. (2) a-Alkyl Sulphide Carboxylic Acids are obtained from the interaction of a-halogen fatty acids and sodium mercaptides. (3) a-Mercaptal Carboxylic Acids result from the action of a-thio-acids and alde- hydes. Ethidene-dithioglycollic Acid, CH 3 . CH : (SCH 2 . COOH) 2 , melts at 107. (4) a-Mercaptol Carboxylic Acids result from a-thio-acids and ketones in the pres- ence of zinc chloride or HC1. Dimethylene-dithioglycollic Acid, (CH 3 ) 2 C : (SCH 2 COOH) 2< melts at 126. (5) a- Sulphide Dicarboxylic Acids are produced when K 2 S acts 'upon a-halogen fatty acids. y-^TT C*C\ TT Thiodiglycollic Acid, S melts at 129. In composition it cor- responds to diglycollic acid (p. 339), and under like conditions forms a cyclic anhydride, which is both a sulphide and a carboxylic anhydride. Thiodiglycollic /-TT r^r\ Anhydride, S<^ 2 ^>O, melts at IO2, and boils at 158 (10 mm.) (B. 27, 3059). a- Thiodilaciyl Acid, S[CH(CH 3 ) . CO 2 H] 2 , melts at 125. y- Thiodibutyric Acid melts at 99 (B. 25, 3040). Unsymmetric'al Sulphide dicarboxylic acids are obtained from the disodium salts of the mercaptan carboxylic acids and sodium halogen fatty acids in aqueous solution (B. 29, 1139). (6) a-Disulphide Dicarboxylic Acids are readily produced in the oxidation of the a-mercaptan carboxylic acids in the air, or with ferric chloride or iodine. Dithio- diglycollic Acid, (SCH 2 CO 2 H) 2 , melts at loo. a-Dithiodilactic Acid, [SCH(CH 3 ) .- CO 2 H] 2 , melts at 141. /SH \ Cystem is probably an amido-thiolactic acid, CH 3 .C( NH j .CO 2 H. It is obtained from cystin by reduction with tin and hydrochloric acid. A crystalline powder, very soluble in water, and yielding an indigo-blue color with ferric chloride. In the air it rapidly oxidizes to cystin (B. 18, 258, and 19, 125). Cystin, C fi H 12 N 2 O 4 S 2 , probably dithio-diamido-dilactic acid, ^^CfCHHNH) CO 2 H' occurs in some ca l cu li and urinary sediments. It forms colorless leaflets. It is insoluble in water and alcohol, but dissolves in acids and alkalies. (7) Sulphin-oxide Carboxylic Acids. The free bodies e. g., CH 2 S(CH 3 ) 2 OH, are unstable. They split off water and yield cyclic sulphinates, which are constituted similarly to the cyclic ammonium compounds, and are called thetines. This name, 34^ ORGANIC CHEMISTRY. from the contraction of thio and betaine, is intended to express the analogy between their derivatives and betaine (B. 7, 695 ; 25, 2450; 26, R. 409) : co-o coo Thetine ' C^ACH,)., betaine, p. 310. The thetines are feeble bases. Their hydrobromides are produced when methyl sulphide, ethyl sulphide, and sodium thio-diglycollate are brought into action with a-halogen fatty acids e. g. , chloracetic acid and a-brompropionic acid. Dimethyl Thetine, (CH 3 ) 2 S . CH 2 . CO . O, is deliquescent. Dimethyl Thetine Dicarboxylic Acid, (HO. CO. CH 2 ) 2 S. CH 2 .COO, melts at I57-I58 . Selenetines, see B. 27, R. 801. (8) Sulphone Carboxylic Acids are produced by the action of alkyl sulphinates upon esters of halogen fatty acids. They recall the ketone carboxylic acids (see these). Ethyl Sulphone Acetic Acid, C 2 H 5 . SO 2 . CH 2 . CO 2 H . Ethyl Sulphone Propioni<~, Acid, C 2 Hg . SO 2 . CH 2 . CH 2 . CO 2 H (B. 21, 89, 992). By oxidizing the sulphide, corresponding to the sulphones with KMnO 4 we obtain : Sulphone Diacetic Acid, O 2 S(CH 2 CO 2 H) 2 , melting at 182. a-Sulphone Dipropionic Acid, O 2 S[CH(CH 3 ) .- CO 2 H] 2 , melts at 155 (B. 18, 3241). Sulphone diacetic acid resembles aceto- acetic ester in many respects. For mixed sulphone-di-fatty acids see B. 29, 1141. (9) a-Sulpho-carboxylic Acids. The sulpho-acids of the fatty acids are pro- duced by methods similar to those employed with the alkyl sulphonic acids : (1) By the action of sulphur trioxide upon the fatty acids, or by acting with fuming sulphuric acid on the nitriles, or amides of the acids. (2) By heating concentrated aqueous solutions of the salts of the monosubstituted fatty acids with alkaline sulphites. (3) By the addition of alkaline sulphites to unsaturated acids (B. 18, 483). (4) By oxidizing the thio-acids corresponding to the oxy-acids with nitric acid. (5) Upon oxidizing glycol sulphonic acids, e. g., isethionic acid, with nitric acid. These sulpho-acids are dibasic acids. They correspond to the dicarboxylic acids, like malonic acid. The sulpho-group in them is not so intimately combined as in the sulphonic acids of the alcohol radicals. Boiling alkalies convert them into oxy- acids. Sulpho-acetic Acid, CH 2 <^ 2 ^ OHl ^ H 2, fuses at 75. Pentachloride of SO Cl phosphorus converts it into a chloride, CH 2 NH, melting at 142. It deports itself like the imides of the dicarboxylic acids, e. g., succinimide (see this) and n-glutarimide. The readily decomposable additive products, arising from ammonia and the y-lactones (A. 56, 147), are viewed as y-oxyacid amides. Yet they are said to have a constitution similar to aldehyde- ammonia (A. 259, 143). The additive product from ammonia and y-valerolactone may have one of the following formulas : CH 3 CHCH 2 CH 2 CONH 2 or CH 3 . CH . CH 2 . OH 6 2. Hydrazides of the Oxyacids : Glycol Hydrazide, HO . CH 2 . CO . NH . NH 3 , melting at 93, has been prepared from benzoyl or oxalyl glycollic ester and hydrazine hydrate (J. pr. Ch. [2] 51, 365). 3. Azides of the Oxyacids : Glycol Azide, HO . CH 2 . CON 3 , is formed when sodium nitrite acts upon the hydrochloride of glycol hydrazide. It crystallizes from ether (J. pr. Ch. [2] 52, 225). 4. Nitriles of the Oxy-acids. The nitriles of the a-oxy-acids are the additive products obtained from hydrocyanic acid and the aldehydes, and ketones. The aldehydes yield nitriles of secondary oxy-acids. Formaldehyde is an exception in this respect, for it affords the nitrile of a primary oxy-acid, glycollic acid. The ketones yield nitriles of tertiary oxy-acids. CH 3 . CH : O + CNH = CH 3 . CH< nitrile of lactic acid (p. 335). f-vr (CH 3 ) 2 C : O + CNH = (CH 3 ) 2 C C H 4CO> V-H 2 siTo^N^ Potassium Phthalimide Phthalylglycocoll Ester. (3) The reduction of nitro- and isonitroso-acids (p. 350) with nascent hydrogen (Zn and HC1) : CH 2 N0 2 . CO . O . C 2 H 5 "--> CH 2 NH 2 . COOH Nitro-acetic Ester Amido-acetic Acid CH 3 . C : (NOH) . COOH - >- CH 3 . CH(NH 2 )COOH a-Oximidopyroracemic Acid Alanine, a-Amidopropionic Acid. 352 ORGANIC CHEMISTRY. (4) Transposition of the cyan-fatty acids (see these) with nascent H (Zn and HC1, or by heating with HI), in the same manner that the amines are produced from the alkyl cyanides (p. 266) : CN . CO . OH -f 2 H 2 = CH 2 (NH 2 ) . CO 2 H Cyanformic Acid Amido-acetic Acid. This reaction connects the amido-fatty acids with the fatty acids containing an atom less of carbon, and also with the dicarboxylic acids of like carbon content, whose half nitrites are the cyan-fatty acids. (5) The nitriles of the a-amido-acids are prepared by allowing a calculated quantity of ammonia, in alcoholic solution, to act upon the hydrocyanic acid additive products of the aldehydes and ketones, and then setting free the hydrochlorides of the a-amido-acids from these by means of hydrochloric acid (B. 13, 381 ; 14, 1965) : CHs . CHO (CH 3 ) 2 CO (6) Nitriles of a-amido-acids can also be synthetically obtained (a) from the aldehyde ammonias by means of hydrocyanic acid ; (^) from aldehydes by means of ammonium cyanide (B. 14, 2686) : CNNH 4 -H 3 .C. Prussic acid attaches itself similarly to the oximes (B. 25, 2070), to the hydra- zones, and to the Schiff bases, with the production of nitriles (B. 25, 2020). The 5th and 6th methods are only suitable for the production of a-amido-fatty acids, while the remaining methods serve also for the preparation of/?-, p-, and <5-amido-fatty acids, which are also produced : (7) By the addition of ammonia to unsaturated acids, as well as (8#) by the oxidation of amido-ketones, e. g., diacetonamine (p. 219), and (8<) by the breaking down of the cyclic imides of glycols upon oxida- tion, see piperidine. Properties. The amido-acids are crystalline bodies with usually a sweet taste, and are readily soluble in water. As a general thing, they are insoluble in alcohol and ether. Constitution. As the amido-acids contain both a carboxyl and an amido-group, they are acids and bases. Since, however, the carboxyl and amido-groups mutually neutralize each other, the amido-acids show neutral reaction, and it is very probable that both groups com- bine to produce a cyclic ammonium salt : NITROGEN DERIVATIVES OF THE OXY-ACIDS. 353 The existence and method of producing trimethyl glycocoll or betaine would indicate this. A separation of the two groups would again occur in the formation of the salts. Deportment. The amido-acids form (i) metallic salts with metallic oxides, and (2) ammonium salts with acids. (3) The hydrogen of the carboxyl group can be replaced by alcohol radicals with for- mation of esters, which are, however, unstable. On the other hand, the hydrogen of the arnido-group can be replaced by both acid and alcohol radicals. (4) The acid derivatives appear when acid chlorides act upon the amido-acids or their esters : C2H3 + HC1 ' Acetyl Amido-acetic Acid. whereas (5) the alcohol derivatives are obtained by the action of the amines on sub- stituted fatty acids : CH 3 C1 . C0 2 H + NH(CH 3 ) 2 = CH 2 <3 2 + H C1. Dimethyl Glycocoll. (6) By continuing the introduction of methyl into the amido-acids it is possible to entirely split off the amido-group. Unsaturated acids result. Thus, a-amidopro- pionic acid yields acrylic acid, and a-amido-butyric acid yields crotonic acid (B. 21, R. 86), while a-amido-n- valeric acid yields propylidene acetic acid (B. 26, R. 937). (7) When the amido-acids are heated to 200 with hydriodic acid they exchange their amido-group for hydrogen and become fatty acids (B. 24, R. 900). They are not affected by boiling alkalies, but (8) when fused they decompose into salts of the fatty acids and into amines or ammonia. (9) By dry distillation (with baryta especially) they yield amines and carbon dioxide : CH 3 . CH0 ^ rw >NH LH 2 . CH 2 CH 2 . CH 2 Butyrolactone -y-Butyrolactam, Pyrrolidone 6-Valerolactone fi-Valerplactam , a-Oxopiperidine. a-Amido-acids. Glycocoll, Glycin, Amido-acetic Acid {Amino-ethan CH 2 (NH 2 ) . CO 2 H, melting at 232-236, is obtained synthetically (p. 352) : (i) By heating monochloracetic acid with ammonia (di- and triglycolamidic acids are formed at the same time) or by warming monochloracetic acid with dry ammonium carbonate (B. 16,2827); (2) from phthalylglycocoll ester (B. 22, 426) ; (3) by the reduction of nitro-acetic acid; (4) of cyan-formic acid; (5) by heating methylene amido-acetonitrile with alcoholic hydrochloric acid, when it changes to the hydrochloride of glycin ester (B. 29, 762); (6) from methylene cyanhydrin, the product obtained by the union of formaldehyde and prussic acid. Ammonia converts it into glyco- coll nitrile, which is altered to glycocoll by boiling baryta water (A. 278, 229): CH 2 _ 2 Glycocoll may be prepared by methods 2, 5, and 6, or by the de- composition of hippuric acid (see below). A rather striking forma- tion of glycocoll is observed (7) by conducting cyanogen gas into boiling hydriodic acid : and, finally, (8) by letting ammonium cyanide and sulphuric acid act upon glyoxal, when the latter probably at first yields formaldehyde (B. 15, 3087). History and Occurrence. Braconnot (1820) first obtained glycocoll by decom- posing glue with boiling sulphuric acid. It owes its name to this method of forma- tion and to its sweet taste : y/,i>/crc, sweet, /cd/Ma, glue. Dessaignes (1846) showed that glycocoll was formed as a decomposition product when hippuric acid was boiled with concentrated hydrochloric acid : COOH COOH iH,NH . CO. C 6 H 6 + H > + HQ = iH.NH.Ha + C H * COOH - Hippuric Acid Glycocoll Benzoic Acid. Benzoyl Glycocoll Hydrochloride NITROGEN DERIVATIVES OF THE OXY-ACIDS. 355 Strecker (1848) observed that glycocoll appeared from an analogous decomposi- tion of the glycocholic acid occurring in bile. Compare taurine, p. 306 : COOH COOK Glycocholic Acid Potassium Potassium Amido-acetate Cholate. Glycocoll was first (1858) prepared artificially by Perkin and Duppa, when they allowed ammonia to act upon bromacetic acid. Properties. Glycocoll crystallizes from water in large, rhombic prisms, which are soluble in 4 parts of cold water. It is insoluble in alcohol and ether. It possesses a sweetish taste, and melts with de- composition. Heated with baryta it breaks up into methylamine and carbon dioxide; nitrous acid converts it into glycollic acid. Ferric chloride imparts an intense red coloration to glycocoll solutions; acids discharge this, but ammonia restores it. Metallic Salts. An aqueous solution of glycocoll will dissolve many metallic oxides, forming salts. Of these, the copper salt, (C 2 H 4 NO 2 ) 2 Cu -\- H 2 O, is very char- acteristic. It crystallizes in dark blue needles. The silver salt, C 2 H 4 NO 2 Ag, crys- tallizes on standing over sulphuric acid. The combinations of glycocoll with salts, e. g., C 2 H 5 NO 2 . NO 3 K, C 2 H 5 NO 2 . NO 3 Ag, are mostly crystalline. Ammonium Salts. Glycocoll yields the following compounds with hydrochloric acid : C 2 H 5 NO 2 . HC1 and 2(C 2 H 5 NO g ) . HC1. The first is obtained with an excess of hydrochloric acid. It crystallizes in long prisms. The nitrate, C 2 H 5 NO 2 . HNO 3 , forms large prisms. Esters. The glycocoll esters claim special mention, as they are the starting-out material for the preparation of diazo-acetic esters (p. 365). The ethyl ester, CH 2 <^pQ 2 p TJ is an oil with an odor resembling that of cacao, and boiling at 149. See glycin anhydride or diglycoldi-imide. On leading HC1 gas into glycocoll and absolute alcohol, the HCl-salt is formed ; this melts at 144 (B. 21, R. 253). It is also produced when HC1 is conducted into alcohol and aceturic acid (p. 356) (B. 29, 760), or by the action of alcoholic hydrochloric acid upon methylene amido- acetonitrile (p. 356). Silver nitrite produces the nitrite salt, NOOH . NH 2 COOC 2 H 5 , which readily passes quantitatively into diazo-acetic ester, CH : N 2 CO 2 C 2 H 5 . Amides. Glycocollamide, CH 2 , is betaine, described p. 310. " Ethylamine, diethylamine and triethylamine, acting upon chloracetic acid, pro- duce the ethylated glycocolls in the form of hydrochlorides : CO O Ethyl-glycocoll, Diethyl-glycocoll and Triethyl-glycocoll, i i C H 2 . N(C 2 H 5 ) 3 . The latter boils with decomposition at 210-220, and differs from the ethyl ester COOC 2 H 5 of diethylamidoacetic acid, \ boiling at 177, and resulting from the CH 2 N(C 2 H 5 ) 2 , action of ethyl iodide upon silver amido-acetate (A. 182, 176). Methylene Amido acetonitrile, CH 2 = N . CH 2 CN, melting at 129 with decom- position, is formed from formaldehyde and ammonium cyanide (B. 27, 59). Aceto-glycocoll, CH 2 acetamido- acetic acid, aceturic acid, is obtained by the action of acetyl chloride upon glycocoll silver, and of acetamide upon monochloracetic acid. It dissolves readily in water and alcohol, and melts at 206. It conducts itself like a monobasic acid (B. 17, 1664). Hippuric acid or benzoyl glycocoll (see this) and glycocholic acid (see this), already mentioned under glycocoll, are far more important and will be discussed later. They are constituted like aceturic acid. Diglycolamidic and triglycolamidic acids bear the same relation to glycocoll that di- and trioxyethylamine sustain to oxethylamine : rw rn T-T /CH 2 CO 2 H NH 2 . CH 2 . C0 2 H NH<"2 ' ~X 2 w N^-CH 2 . CO 2 H \CH 2 .C0 2 H \CH 2 .C0 2 H. NH 2 CH 2 . CH 2 OH NH(CH 2 . CH 2 OH) 2 N(CH 2 . CH 2 OH) 3 . These compounds are formed on boiling monochloracetic acid with concentrated aqueous ammonia (A. 122, 269; 145, 49 ; 149, 88). Diglycolamidic Add, NH(CH 2 CO 2 H) 2 , melts at 225, and forms salts both with acids and bases, while Triglycolamidic Acid, N(CH 2 CO 2 H) 3 , cannot unite with acids. Imidoacetonitrile, NH(CH 2 CN) 2 , melting at 75, and Nitriloacetonitrile, N(CH 2 - CN) 3 , melting at 126, are obtained from methylene cyanhydrin and ammonia (A. 278, 229; 279,39). q-Amidopropionic Acid, CH 3 . CH(NH 2 ) . CO 2 H, or CH 3 .CH.- (NH 3 )COO, Alanine, is derived from a-chlor- and a-brom-propionic acid by means of ammonia, and from aldehyde ammonia by the action of CNNH 4 and HC1 (p. 193). Aggregated, hard needles, with a sweetish taste. The acid dissolves in 5 parts of cold water and with more difficulty in alcohol ; in ether it is insoluble. When heated it NITROGEN DERIVATIVES OF THE OXY -ACIDS. 357 commences to char at about 237, melts at 255 and then sublimes. It is partially decomposed into ethylamine and carbon dioxide and in part into aldehyde, carbon monoxide and ammonia (B. 25, 3502). Nitrous acid converts it into a-lactic acid. Isomeric /?-amido-propionic acid will be treated as the first /9-amido- carboxylic acid, p. 358. Higher homologous a-amido- acids have been mainly prepared by the general methods: (i) By the action of ammonia upon the a-halogen fatty acids, or (2) upon the nitriles of the a-oxy-acids. a-Amido-n-butyric Acid, CH 3 . CH 2 . CH(NH 2 ) . CO 2 H. a-Amidoisobutyric Acid, (CH 3 ) 2 C(NH 2 ) . CO 2 H, is also produced in the oxida- tion of diacetonamine sulphate. a- Amido- valeric Acid, CH 3 . CH 2 . CH 2 CH(NH 2 ) . CO 2 H, is also produced by the oxidation of conine (B. 19, 500). a-Amido-isovaleric Acid, (CH 3 ) 2 . CH. CH(NH 2 ) . CO 2 H, Butalanine, occurs in the pancreas of the ox. a-Amidocaproic Acids, Leucines. Different a-amido-caproic acids have been described under the name leucine. Leucine (from Aeuxo?, glistening white, referring to the appearance of the scaly crystals) occurs in different animal fluids. Its occurrence is physiologically very important. It is present in the pancreas, in the spleen, in the lymph-glands, and in typhoid it is found in the liver. It is formed by the decay of albuminoids, or when they are boiled with alkalies and acids. Fibrin is converted into it by pancreatic digestion (B. 27, 2727). Horn or dried neck-band of oxen, when treated with dilute sulphuric acid to 100 yields animal leucine. Strecker (1848) showed that when it was treated with nitrous acid it passed into an oxy-caproic acid, melting at 73 probably a-oxy-n-caproic acid leucic acid, P- 337- Animal leucine crystallizes in shining leaflets, which have a fatty feel, melt at 270 and sublime undecomposed when carefully heated. Rapid heating breaks it up into amylamine and CO 2 . It is soluble in 48 parts of water at 12 and in 800 parts of alcohol. Vegetable leucine from conglutin, the globulin substance of the lupines^ different from the preceding body. It is optically active ; the free amido-acid is Isevo-rotatory in solution, while its hydrochloride is dextro-rotatory. This leucine becomes optically inactive when it is heated to 160 with baryta water. It is then identical with a-amido-isocaproic acid, (CH 3 ) 2 . CH . CH 2 .CH(NH 2 ) . COOH, prepared syntheti- cally from isovaleric aldehyde, (CH 3 ) 2 . CHCH 2 . CHO. Nitrous acid converts both acids into a-oxy-isocaproic acid, (CH 3 ) 2 . CHCH 2 CH(OH)CO 2 H, melting at 54 (P- 337)- Penicillium glaucum converts inactive a-amido-isocaproic acid into opti- cally active dextro-le uc ine ; the free amido-acid being dextro-rotatory in solution and its hydrochloride lasvo-rotatory (B. 24, 669 ; 26, 56). Therefore, the three modifica- tions of a-amido-iso caproic acid are known. a-Amhlo-cenanlkic Acid, CH 3 (CH 2 ) 4 CH(NH 2 )CO 2 H (B. 8, 1168). a Amido- caprylic Acid, CH 3 (CH 2 ) 6 CH(NH 2 )CO 2 H (A. 176, 344). a-Amidopalmitic Acid, CH;(CH 2 \ 3 CH(NH 2 )C0 2 H (B. 24, 941). a-Amidostearic Acid, CH 3 (CH 2 ) 15 CH- (NH 2 ) .CO 2 H, melts at 221 (B. 24, 2395). Cyclic Double-acid amides of the a-Amido Carboxylic Acids, a^-Diacipiperazines. In the formation of esters of the 35 8 ORGANIC CHEMISTRY. a-oxyacids by the action of the carboxyl group and the alcoholic hydroxyl group two molecules enter the reaction. This is also the case in the amide-formation between the carboxyl group and the amido-group of the a amido-acids. Cyclic double-acid amides corre- spond to the cyclic double esters or lactides. Diethylenediamine, Piperazine or Hexahydropyrazine (p. 314), is the starting-out substance from which such bodies can be obtained as oxygen substitution products. Hence we have names such as ay-diketo-, ay-diaci-, ay-dioxypiperazine, by means of which we can distinguish the four carbon atoms of the piperazine ring, as a -,/?-, y-, and d-carbon atom : HN NH HN NH y S Diglycollide Diglycolyldiamide, Diethylenediamine, ay-Diacipiperazine Piperazine. The aromatic piperazine derivatives are particularly numerous (B. 25, 2941). fl-T (~"O Diglycolyldiamide, Glycin Anhydride, ay-Diacipiperazine, HN<^Q 2 Urj >NH, turns brown at 245, melts at 275, and is formed when amido-acetic ethyl ester is evaporated with water (B. 23, 3041). Diglycolyldimethylamide, Sarcosine Anhydride, CH 3 N<^ 2 ' C ( J^ ) >N . CH 3 , melting at 150 and boiling at 350, is produced by heating sarcosine (B. 17, 286). Dilactyldiamide, Lactimide, H N<%9>NH, melting at 275, is formed when alanine is heated with hydrochloric acid gas at 180-200 (A. 134, 372). /3-Amido-carboxylic Acids. Neither cyclic double-acid amides, such as are obtained from the a-amidocar- boxylic acids, nor cyclic simple acid amides or lactams, such as are obtained from the y- and d-amidocarboxylic acid, can be prepared from the poorly studied /3-amido- carboxylic acids. ^-Amidopropionic Acid, /3-Alanine, CH 2 (NH 2 ) . CH 2 . CO 2 H, melts at 196 and breaks down into ammonia and acrylic acid. It is isomeric with alanine (p. 356) and is obtained from /3-iodpropionic acid with ammonia from /3-nitropro- pionic acid, and also from succinimide and succinbromimide by means of bromine and caustic potash (B. 26, R. 96). /3-Amidobutyric Acid, CH 3 . CH(NH 2 ) . CH 2 . CO 2 H(?), is produced when crotonic acid is heated with ammonia (B. 21, R. 523). /3-Amido-isovaleric Acid, (CH 3 ) 2 C(NH 2 ) . CH 2 . CO 2 H, is obtained by the re- duction of the corresponding nitro-acid (p. 350). Y- and <5-Amido-carboxylic Acids. The most important characteristic of the Y~ and ^-amido-carboxylic acids is that when heated they part with water and yield cyclic, simple acid amides or lactams, the y-tactams and the ^-lactams. Piperidine derivatives, when oxidized, have yielded some of these acids (Schotten). Potassium phthalimide affords a general synthetic method. Ethylene bromide or tri- methylene bromide acted upon by it changes to w-bromethyl-phthalimide and w-brom- propyl-phthalimide (Gabriel). These bodies, as is known, have also been utilized in the preparation of oxalkylamines (p. 309). In order to get y- and J-amido-carboxylic acids by their aid they are transposed with sodium malonic ester and sodium alkyl- NITROGEN DERIVATIVES OF THE OXY-ACIDS. 359 malonic ester. The condensation product resulting in this manner is decomposed, on heating it with hydrochloric acid, into phthalic acid, y-, or J-amido carboxylic hydrochloride, carbon dioxide and alcohol (B. 24, 2450) : { [2]CO> NCH ' ' CH ' ' CH * Br w-Bromethyl-phthalimide , w-Brompropyl-phthalimide 6 i , N H < I f 2 lC0 2 H I [2jUJ 2 rl C 6 H 4 NH 2 [CH 2 ] 3 C0 2 H C 6 H 4 ' + NH 2 (CH 2 ) 4 CO 2 H Y -Amidobutyric Acid llpAV 1 6-Amido-valeric Acid. y-Amidobutyric Acid, Piperidic Acid, melts at 183-184 andjoses water. It is formed (i) when piperidylurethane, CH 2 < 2 ' ^ 2 >N . CO 2 C 2 H 5 , is oxidized with nitric acid (B. 16, 644) ; (2) by means of potassium phthalimide ; either (a) by the double decomposition of brom-ethyl phthalimide with sodium malonic ester (see above), or (b) by transposing w-brompropyl-phthalimide with potassium cyanide, and decomposing the phthalyl-y-amidobutyric nitrile (B. 23, 1772). 7-Amidovaleric Acid, CH 3 . CH(NH 2 ) . CH 2 . CH 2 . CO 2 H, results from the decomposition of phenylhydrazone-laevulinic acid by sodium amalgam (B. 27, 2313). It melts at 193. Both y-amido-acids, when heated, pass into lactams. (5-Amido-n-valeric Acid, NH 2 (CH 2 ) 4 . CO 2 H (Homopiperidic Acid), melts at 158. Its benzoyl derivative and sulpho-b-amido-valeric acid, SO 2 [NH(CH 2 ) 4 - CO 2 H] 2 , melting at 163, are formed when benzoyl 'piperidine, CH 2 and sulphopiperidine are oxidized with KMnO 4 (B. 21, 2240). The acid results from phthalyl propyl malonic diethyl ester (B. 23, 1769). In the latter manner the follow- ing acids have been prepared: a-Methyl-J-amido-n-valeric acid, NH 2 . CH 2 . CH 2 . - CH 2 . CH(CH 3 )CO 2 H, melting at 168; a-Ethyl-(J-amido-n-valeric acid, NH 2 . CH 2 . - CH 2 . CH 2 .CH(C 2 H 5 )CO 2 H, melting at 200-200.5; a-Propyl-d-amido-n-valeric acid, NH 2 .CH 2 .CH 2 .CH 2 .CH(C 3 H 7 )CO 2 H, melting at 186 (B. 24, 2444). 6-Amido n-Odanic Acid, Homoconinic acid, C 3 H 7 . CH(NH 2 ) . CH 2 . CH 2 . CH 2 . - CO 2 H, melts at 158. Its benzoyl derivative is produced when benzoyl conine is oxidized with potassium permanganate (B. 19, 502). r- and ^-Lactams : Cyclic Amides of the Y- and 5-Amido- carboxylic Acids. These bodies are formed when the f- and (5-amido-acids are heated to their point of fusion. They then lose water, and suffer an intra- molecular condensation. Some of them have been obtained by the reduction of the anilchlorides of dibasic acids e.g., dichlormalein anilchloride. They correspond to the ^- and <5-lactones. The names Hactams and ^-lactams have been given them to recall the lactones. They are cyclic acid-amides. Just as the lactones, under the influence of the caustic alkalies, yield oxy-acid salts, so the lactams, when digested with alkalies or acids, pass into salts of the amido-acids, from which they can be formed on the application of heat. Further, the Y~ and d-lactams bear the same relation to the imides of the f- and d-alkylen diamines as the lactones sustain to the oxides 3 6o ORGANIC CHEMISTRY. of the Y- and <5-glycols (p. 343). following arrangement : CH 2 . CH 2 OH CH 2 . CH 2 . NH 2 CH 2 . CH 2 OH CH 2 . CH 2 . NH 2 Tetramethylene Tetramethylene Glycol Diamine CH 2 . CH 2 CH 2 . CH 5 These relations are apparent in the . CH 2 OH Pentamethylene Glycol T .CH 2 .CH 2 .NH, 1 2 O 6*;.CH> NH y-Butyrolactone -y-Butyrolactam, a-Pyrrolidone Pentamethylene Oxide 2\PH flT .- \^in . ^n. 2 5-Valerolactone Pentamethylene Imide, Piperidine 6-Valerplactam, a-Oxopiperidine, a-Piperidone. y-Lactams : y-Butyrolactam, a-Pyrrolidone, I 2 ' >NH, melting at 25 to 28 and boiling at 245, unites with water to a crystalline hydrate, C 4 H 7 ON -f H 2 O, melting at 35. n-Phenyl-y-butyrolactam is produced in the reduction of di- chlormalem anilchloride (B. 28, "58). y- Valerolactam* d-methyl pyrrolidone, CH 2 - CH(CH 8 ) . MH i ^> INri > melting at 37 and distilling without decomposition, is re- CH 2 CO duced by amyl alcohol and sodium to a-methyl pyrrolidine (p. 315) (B. 22, 1860, 3338, 2364; 23, 708). d-Lactams : 6- Valeroladam , n-Ketopiperidine, a-Oxopiperidine, a-Piperidone, CH 2 NH ' melts at 39-4 and boils at 2 5 6 ( B - 2I 22 4 2 )- --^^- >iperidone,CH 2 <(^CO >NH) meltgat53 50to550 a-Ethyl-6-valerolactam, ^-Ethyl Piperidone, CH 2 <5>NH, melts at 68 and boils at 140-142 (42 mm.) (B. 23, 3694). a-Propyl-8-valerolactam, / 8-PropylPiperidone,CH 2 <^(^3^^C^ > NH, melts at 59 and boils at 274. /~NH , melts at 84. CH 2 . CH C 3 H T The amido-acids are not poisonous, but their y- and J-lactams are violent, strych- nine-like poisons, affecting the spinal cord and producing cramps. We shall again meet these bodies under the pyrrol and pyridine derivatives, where they will appear as tetrahydropyrrol and piperidine compounds. 9. Fatty Acid Nitramines, Nitramine- acetic Acid, CO 2 H . CH 2 . NH . NO 2 (?), melting at 103, is prepared by saponifying its ethyl ester (melting at 24), which results on treating nitrourethane acetic ester, CO 2 C 2 H-. CH 2 N(NO 2 )CO 2 C 2 H 5 , with ammonia (B. 29, 1682). 10. Isonitramine Fatty Acids are obtained in the form of their sodium salts when sodium isonitramine acetoacetic esters and sodium isonitramine-mono-alkyl aceto- acetic esters are acted upon by the alkalies (B. 29, 667). They are converted into amidoxy-fatty acids by dilute mineral acids (p. 350). Acid reducing agents change them to amino-fatty acids, while alkaline reducing agents produce diazo-acids (p. 365) and hydrazino-acids (see below). UNSATURATED OXY-ACIDS, OXY-OLEKINE CARBOXYLIC ACIDS. 361 O honitrci mine-acetic Acid, CO 2 H . CH,N< i , and its homologues are syrupy, easily decomposable liquids. Their lead salts dissolve with difficulty. II (a). Hydrazino-fatty Acids are obtained, together with the diazo-acids, when the isonitramine-fatty acids are acted upon with alkaline reducing agents. Their carbamide derivatives are obtained in the form of nitriles when prussic acid adds itself to the ketone semicarbazides. a-Hydrazino-propionic Acid, Amido-alanine, NH 2 ,- NH . CH(CH 3 )CO 2 H, melting at 180, is formed from a-isonitramine propionic acid (B. 29, 670). a-Hydrazinobutyric Acid, NH 2 . NH . C(CH 3 > 2 CO 2 H, melts, with de- composition, at 237. It is formed when steam acts upon its benzal derivative. The latter is made by acting on acetone semi-carbazide, NH.CO . NH . N = C(CH 3 ) 2 , with prussic acid, when carbonamid-hydrazino-isobutyronitrile is produced. This is then decomposed with hydrochloric acid, and benzaldehyde is added (A. 290, 15). s-Phenylhydrazino-acetic Acid, C 6 H 5 NH . NH . CH 2 . CO 2 H, melting at 158, is produced by the careful reduction of phenylhydrazone-glyoxylic acid, and when chloracetic acid acts upon phenylhydrazine (B. 28, 1230). \\r\sym.-Phenylhydrazino- acetic Acid, C 6 H 5 N(NH,)CH 8 . CO 2 H, melts, with decomposition at 167 (B. 28, 1226). II (). Hydrazo-fatty Acids. When ahydrazino-fatty acid is treated with acetone and potassium cyanide, ahydrazo-nitrile acid results : thus, from a-hydrazino-isobutyric acid we get hydrazo-isobutyro-nitrilic acid, (CH 3 ) 2 C<^^,Q ^ pvf^>C(CH 3 ) 2 , melting at 100. When hydrazine sulphate (l mol.), acetone (2 mols. ), and potassium cyanide (2 mols.) react, the product is Hydrazo-hobntyronitrik, (CH 3 ) 2 C

C(CH 3 ) 2 , melting at 223 (A. 290, l). 12. Azo-fatty Acids. Bromine water oxidizes hydrazo-estersand hydrazonitriles M- AT to the corresponding azo bodies. Azo-isobutyronitrile, (CH 3 ) 2 C< C ^ ^>C- (CH 8 ) 2 , melting at 105, when heated alone, or, better, with hot water, passes into tetramethyl succinic nitrile (A. 290, l). B. UNSATURATED OXY-ACIDS, OXY-OLEFINE CARBOXYLIC ACIDS. The a-acids are formed when their nitriles, the additive products arising from hydrocyanic acid and unsaturated aldehydes, are treated with cold hydrochloric acid. When boiled with dilute hydrochloric acid, the a-oxy-A/?y-unsaturated acids are rearranged into y-ketone carboxylic acids (Fittig, B. 29, 2582) e. g., crotonaldehyde yields : CH 3 . CH : CH . CH boiling at 156, and possessing an odor like that of X CH= CH X pyridine (B. 24, 3144). Pseudohttidostyril, [3.5] -dimethyl-a-pyridone, viesitene lactam , CO )NH, CH=:C(CH 3 )/ melting at 180 and boiling at 305, is formed when ammonia acts upon mesitene lactone, and from the two monocarboxylic acids of this lactam by the elimination of CO 2 (A. 259, 1 68). 8. ALDEHYDE ACIDS. These are bodies which show both the properties of a carboxylic acid and of an aldehyde. Formic acid is the simplest representative of the class, and it is also the first member of the homologous series of saturated aliphatic monocarboxylic acids. But it and its derivatives 364 ORGANIC CHEMISTRY. have been, with repeated reference to its aldehydic nature, discussed before acetic acid and their higher homologues. The best known alde- hyde carboxylic acid, a compound of the aldehyde group CHO with the carboxyl group COOH, is glyoxylic acid, which is an oxidation product of ethylene glycol. Glyoxylic Acid, Glyoxalic Acid [Ethanal Acid] (HO) 2 . CH .- CO 2 H, was found by Debus (1856) among the products resulting from the oxidation of alcohol with nitric acid. It occurs in the unripe gooseberries. Just as chloral hydrate is to be considered as trichlorethi- dene glycol, CC1 3 CH(OH) 2 , so crystallized glyoxylic acid can be re- garded as the glycol corresponding to the aldehydo-acid, CHO . CO 2 H. All the salts are derived from the dihydroxyl formula of glyoxylic acid ; hence it may be designated dioxy-acetic acid. Like "chloral hydrate, glyoxylic acid in many reactions deports itself like a true aldehyde (B. 25, 3425)- Methods of Formation. Glyoxylic acid is obtained by(i) oxidizing glycol, alcohol and aldehyde together with glyoxal and glycollic acid ; (2) by heating dichlor- and dibrom-acetic acid to 230 with water (B. 25, 714); (3) by boiling silver dichlor-acetate with water (B. 14, 578); also from hydrazi-acetic acid (p. 366). Properties. It is a thick liquid, readily soluble in water, and crys- tallizes in rhombic prisms by long standing over sulphuric acid. The crystals have the formula C 2 H 4 O 4 . It distils undecomposed with steam. Salts. When dried at 100, the salts have the formula C 2 H 3 MeO 4 . The ammo- nium salt alone has the formula C 2 H(NH 4 )O 3 . The calcium salt, (C^O^Ca, crystallizes with one and two molecules of water (B. 14, 585), and is sparingly solu- ble in water. Deportment. Glyoxylic acid manifests all the properties of an aldehyde. It re- duces ammoniacal silver solutions with formation of a mirror, and combines with pri- mary alkali sulphites (p. 191), with phenylhydrazine (B. 17, 577), with hydroxylamine, thiophenol and hydrochloric acid (B. 25, 3426). When oxidized (silver oxide), it yields oxalic acid ; by reduction it forms glycollic acid and racemic acid, CO 2 H .- CH(OH) . CH(OH)COOH. On boiling the acid with alkalies, glycollic and oxalic acids are produced (B. 13, 1931). This reaction is extramolecular. It completes itself by the intramolecular rear- rangement of the glyoxal, under like conditions, into glycollic acid : COOH COOH COOH CHO 2 + H 2 = + Glyoxylic Glycollic Oxalic Acid Acid Acid. When hydrocyanic and hydrochloric acids act upon glycollic acid, a like transpo- sition ensues. See conversion of urea into allantoin. The acids obtained by the condensation of formic ester with acetic ester and mono-alkyl acetic esters are unsaturated /3-oxy-acids. They were formerly thought to be /3-aldehydo-acids. Formyl Acetic Acid,' CHO . CH 2 /COOH, is of this class. Oxy-methylene Acetic Acid, HO . CH : CH . CO 2 H, is another. These oxy-methylene fatty acids have been already described in connection with the oxy-paraffin carboxylic acids (p. 361). NITROGEN DERIVATIVES OF THE ALDEHYDO-ACIDS. 365 UNSATURATED ALDEHYDO-ACIDS. Mucochloric Acid, the half-aldehyde of dichlormaleic acid, CHO.CC1 = CC1.CO,H, melting at 125, and mucobromic acid, CHO. CBn=CBr. CO 2 H, melting at 122 (15 28, 1886), produced in the action of chlorine and bromine upon pyromucic acid, are probably substitution derivatives of the unknown acid CHO . CH = CH . CO 2 H (Beilstein, L. Jackson and Hilh. Furthermore, the following constitutional formula XC CH OH has been proposed for these acids: \i' m >O ( A - 2 39. l?7)- This would seem to indicate that the acids are y-oxylactones (compare y-ketone carboxylic acids). BrC.CHO.CO.CH 3 Acetyl Mucobromic Acid, >O , melts at 50. BrC.CO. NITROGEN DERIVATIVES OF THE ALDEHYDO-ACIDS. Diazoacetic acid, N 2 CH . CO 2 H, is the most remarkable derivative of glyoxylic acid. As it contains two doubly-linked nitrogen atoms, it maybe compared to the aromatic diazo-bodies (see diazobenzene). However, in the latter the extra affinities of the diazo-group N=N or =N=N are combined to two atoms, while in diazoacetic acid N they are joined to a single carbon atom, n^CH.CO 2 H. Separated by acids from its salts, it undergoes an immediate decomposition, but it is quite stable in its esters and its amides. The sodium salts of the diazo-acids have been prepared by reducing the isonitramine fatty acids (p. 360) with sodium amalgam (W. Traube, B. 29, 667): HO 2 N 2 CH 2 CO 2 H + 2H = 2H 2 O -f N 2 : CH . CO 2 H. The esters of the diazo-acids result when potassium nitrite acts upon the hydrochlorides of the amido-fatty acid esters (p. 355) (Curtius, 1883, B. 29, 759): HC1 . (H 2 N)CH 2 . CO 2 C 2 H 5 -f NO 2 K = N 2 : CH . CO 2 C 2 H 5 -f KC1 + 2H 2 O. Glycocoll Ester Diazoacetic Ester. Hydrochloride The diazo-acids are very volatile, yellow-colored liquids, with peculiar odor. They distil undecomposed with steam, or under reduced pressure. They are slightly soluble in water, but mix readily with alcohol and ether. Like acetoacetic ester, they are feeble acids ; the hydrogen of their CHN 2 -group can be replaced by alkali metals. This change may be effected by the action of alcoholates. Aqueous alkalies gradually saponify and dissolve them, with the formation of salts, CHN 2 . - CO 2 Me. Acids decompose these at once with the evolution of nitrogen. Sodium amalgam reduces them to hydrazino-acids (B. 29, 667). Sodium diazoacctate, yellow in color, dissolves with extreme ease in water. The reaction of its solution is alkaline. Ethyl Diazoacetate, CHN 2 . CO 2 . C 2 H 5 , boils "at 143-144 (under 120 mm. pressure); itssp.gr. is 1.073 at 22 - V\ hen chilled it solidifies, forming a leafy, crystalline mass, melting at 24. It explodes with violence when brought in con- tact with concentrated sulphuric acid. A blow does not have this effect. It is a 366 ORGANIC CHEMISTRY. feeble acid. Its mercury salt, Hg(CN 2 . CO 2 . C 2 H-) 2 , melts with foaming at 104. It results when yellow mercuric oxide acts upon diazoacetic ester. The mixture should be well cooled. It separates from ether in transparent, sulphur-yellow, rhombic crystals. Concentrated ammonia converts it, like all other esters, into an amide, diazoacetamide, CHN 2 .CO.NH 2 , melting at 114 with decomposition. When diazoacetic ester is reduced it breaks down into ammonia and glycocoll. NH Hydrazi-acetic acid, I T >CH . CO 2 H, stable only in the form of its salts, is an inter- mediate product. Acids decompose it into hydrazine and glyoxylic acid (B. 27, 775). The diazo compounds of the marsh- gas series are especially reactive. They split off nitrogen, and its place is taken either by two univalent atoms or radicals. (i) The diazo-esters are converted, by boiling water or dilute acids, into esters of the oxy-fatty acids (glycol acids, p. 330) : CHN 2 . CO 2 . C 2 H 5 -f H 2 O = CH 2 (OH) . CO 2 . C 2 H 5 + N 2 Ester of Glycollic Acid. This reaction can serve for the quantitative estimation of the nitrogen in diazo- derivatives. (2) Alkyl glycollic esters are produced on boiling with alcohols : CHN 2 . C0 2 . C 2 H 5 -f C 2 H 6 . OH = CH 2 (O . C 2 H 5 ) . CO 2 . C 2 H 5 -f N 2 ; Ethyl Glycollic Ethyl Ester. a small quantity of aldehyde is produced at the same time. (3) Acid derivatives of the glycollic esters are obtained on heating the diazo-com- pounds with organic acids : CHN 2 . CO 2 . C 2 H 5 -f C 2 H 3 O . OH = CH 2 (O . C 2 H 3 O) . CO 2 . C 2 H 5 + N 2 . Acetic Acid. Aceto-glycollic Ester. (4) The haloid acids act, even in the cold, upon the diazo-compounds. The products are haloid fatty acids : CHN 2 . C0 2 . C 2 H 5 -f HC1 = CH 2 C1 . CO 2 . C 2 H 5 + N 2 . (5) The halogens produce esters of dihaloid fatty acids : CHN 2 . CH 2 . C 2 H 5 -f I 2 = CHI 2 . CO 2 . C 2 H 5 -f N 2 . Di-iodo-acetic Ester. Diazo-acetamide is changed, in a similar manner, to di-iodo-acetamide, CHI 2 . CO. NH 2 . By titration with iodine it is possible to employ this reaction for the quantitative estimation of diazo-fatty compounds (B. 18, 1285). (6) The esters of anilido-fatty acids, C 6 H 5 . NH . CH 2 . CO 2 R, result from the union of the anilines with diazo esters. (7) They revert to the amido-acids upon reduction (with zinc dust and glacial acetic acid). Hydrazine-fatty acids are inter- mediate products. These are not very stable (B. 17, 957)- (8) The esters of the diazo-fatty acids unite with aldehydes to form esters of the ketonic acids, e. g., benzoylacetic ester, C 6 H 5 . CO . CH 2 . CO 2 . C 2 H 5 (B. 18, 2379). (9) Diazo-acetic ester produces a peculiar ester by its union with benzene. This compound is isomeric with phenyl-acetic ester, C 6 H 5 . CH 2 . CO 2 C 2 H 5 (B. 18,2377). It probably has one of the following constitutional formulas : ,CH / CH v CH X I ^CH CH^ X CH. || HCX || . or | | >CHX, CH, I ,CH CH, in which X represents the group CO 2 C 2 H 5 (B. 29, 108). NITROGEN DERIVATIVES OF THE ALDEHYDO-ACIDS. 367 (10) The diazoacetic esters and the esters of the unsaturated acids (acrylic, cinnamic, fumaric) combine to additive products, which crystallize well : || -f N 2 CH.C0 2 R = | R O 2 C . CH N NH CH . CO 2 R Acrylic Ester Diazoacetic Ester 3. 4-Pyrazoline Dicarboxylic Ester. On the application of heat nitrogen is split off, and an ester of trimethylene dicarboxylic acid results : CH CH I )N 2 :CH.C0 2 R= I )CH.C0 2 R RO.CCH / Trimethylene-dicarboxylic Ester. Starting with diazoacetic esters Curtius obtained diamide or hydra- si/ie, NH a NH 2 (B. 27, 775) and from the latter hydronitric acid, N 3 H, hydrazoic acid. Triazo-acetic Acid, Triazo-trimethylene-tricarboxylic acid, .N 2 CHC0 2 H C0 2 H.CH( >N 2 , X N 2 CHCOjH a polymerization product of diazo-acetic acid, is the starting-out material for the preparation of diamide. Its sodium salt is formed when concentrated sodium hydroxide acts upon diazo-acetic ester; it crystallizes with 3H 2 O in brilliant, orange-yellow plates, which melt at 152 when rapidly heated (B. 22, R. 133, 196). The acid is almost insoluble in cold water, ether and benzene, b NH 2 OH, C 6 H 5 NH . NH 2 , consult " Nitrogen derivatives of the a-ketonic acids." It combines with CNH to form the nitrile of a-oxyisosuccinic acid. The change of pyroracemic acid on boiling with baryta water into uvitic acid, C 6 H 3 - [l. 3. 5](CH 3 )(CO 2 H) 2 , and uvic acid or pyrotritartaric acid, is most interesting., The uvitic acid formation is due to a condensation of pyroracemic acid with acet- aldehyde. This is a reaction capable of wider generalization. For the condensation of the acid with formaldehyde consult tetramethylene dioxalic acid. Halogen Substitution Products of Pyroracemic Acid. Trichlorpyroracemic Add, Isotrichlor-glyceric Acid, CC1 3 . CO . CO 2 H + H 2 O = CC1 3 . C(OH) 2 COOH, melting at 102, is produced (i) when KC1O 3 and HC1 act upon gallic acid and salicylic acid ; (2) by the action of chlorine water upon chlorfumaric acid (B. 26, 656) 5 (3) from trichlor-acetyl cyanide. Substitution products result by heating the acid with bromine and water to 100 ; dibrom-pyruvic acid, CBr 2 H . C(OH) 2 CO 2 H -f H 2 O, melts at 89, anhydrous. Tribrom-pyruvic acid, CBr 3 . C(OH) 2 . CO 2 H -f H 2 O, fuses at 90 , anhydrous. When heated with water or ammonia, it breaks up into bromoform, CHBr 3 , and oxalic acid. Homologues of Pyroracemic Acid. Propionyl-carboxylic Acid, C 2 H 5 ,CO. CO 2 H, boils at 74-78 (25 mm.). Butyryl-carboxylic Acid, C 3 H 7 . CO . CO 2 H, boils at 185 (82-84 mm.). Trimethyl-pyroracemic Acid, (CH 3 ) 3 . C . CO . CO 2 H, results from the oxida- tion of pinacoline with potassium permanganate. It melts at 90 and boils at 185 (B.2 3 , R. 21). Nitrogen Derivatives of the a-Ketonic Acids. (l). a-Ketone amides are produced by the action of cold concentrated hydro- chloric acid upon the a-ketone nitriles. Pyroracemamide, CH S . CO . CO . NH 2 , melts at 124. Propionyl Formamide, C 2 H 5 CO.CO. NH 2 , melts at 116 (B. 13,21211. (2) a-Ketone Nitriies. result on heating acid chlorides or bromides with silver cyanide : C 2 H 3 OC1 + AgCN = C 2 H 3 O . CN -f AgCl ; and when the aldoximes of the a-aldehyde ketones are treated with dehydrating agents, such as acetic anhydride (p. 326; B. 20, 2196) : CH 3 . CO . CH : NOH = CH 3 . CO . CN -f H 2 O. The acid cyanides are not very stable, and, unlike the alkyl cyanides, are con- verted by water or alkalies into their corresponding acids and hydrogen cyanide, CH 3 . CO . CN + H 2 O = CH 3 . CO . OH + CNH. With concentrated hydrochloric acid, on the contrary, they sustain a transposition similar to that of the alkyl cyanides (p. 266), i, e., carboxyl derivatives of the acid radicals the so-called -ketonic acids (see these) are produced. Water is absorbed, and the amides of the a-ketonic acids are intermediate products (Claisen) : CH 3 . CO . CN 3 -M;H 8 . CO . CONH 2 -gg->CH 3 COCOOH + NH 4 C1. Acetyl Cyanide, CH 3 . CO . CN, boils at 93. When preserved for some time, or by the action of KOH or sodium, it is transformed into a polymeric, crystalline CH, compound, (C 2 H S OCN) 2 , diacetyl cyanide, probably CH 3 . CO . C C . CN (B. 26, N O R. 780). This melts at 69 and boils at 208. Diacetyl cyanide is also produced by the action of potassium cyanide upon acetic anhydride (B. 18, 256). See Isomalic Acid. PARAFFIN KETONE CARBOXYLIC ACIDS. 371 Propionyl Cyanide, CH 3 . CII 2 . CO . CN, boils at 108-110. Dipropionyl Cyanide, (C 3 H 5 O . CN) 2 , melts at 59, and boils at 200-210 (B. 18, R. 140). Butyryl Cyanide, C 3 H 7 . CO . CN, boils at 133-137; isobutyryl cyanide, C 3 H 7 .- (_'O.('N. at 118120. These polymerize readily to dicyanides, which pass into alkyltartronic acids on treatment with hydrochloric acid. (3) Ethylimidopyrmyl chloride, CH 3 C< ) . CC1 : N. C 2 H 5 , is a yellowish oil pro- duced by the union of chloracetyl with ethylisocyanide (A. 280, 298). (4) Chlorisoniirosoacetone, CH 3 COC(NOH)C1, melting at 105, is formed: (1) By the action of nitric acid upon chloracetone ; (2) By the action of chlorine upon isonitrosoacetone ; (3) \\henhydrochloric acid acts upon acetyl-methyl nitrolic acid, CH 3 . CO . C- (= NOH)ONO or CH 3 . CO . C( = NOH)NO 2 the product resulting from the action of nitric acid upon acetone (A. 277, 318). The oxime, CH 3 . C : NOH . C(: NOH)- O . NO, of this acid melts at 97 with decomposition. (5) Imictopyroracetiiic Acid, CH 3 C(NH)CO 2 H, is formed when ammonia acts upon pyroracemic acid, and when it decomposes a picoline dicarboxylic acid results uvi- tonic acid ; by the action of aniline the products are Anilpyruvic Acid, CH 3 . C(: N .- C B H 5 )CO 2 H, which fuses at 126 with decomposition (B.' 27, R. 508) and a quino- line carboxylic acid, aniluvitonic acid. (6) a-Oximido-fatty Acids, or oximes of the a-ketonic acids, result (l) by the action of hydroxylamine upon a-ketonic acids, and (2) when nitrous acid acts upon mono- alkyl acetoacetic esters (B. 15, 1527). In the latter case the acetyl-group is displaced (B. n, 693). Acetic anhydride changes these acids to acid nitriles ; carbon dioxide being eliminated. a-O.\imido-propionic Acid, Isonitroso-propionic Acid, CH 3 . C = N(OH) . CO 2 H, decomposes at 177. a-Oximido-propionic Ethyl Ester, CH 3 C = N(OH)CO 2 C 2 H 5 , melts at 94 and boils at 238 (B. 27, R. 470). a-Oximido-propionamide, CH 3 . - C: N(OH)CONH 2 , melts at 174 (B. 28, R. 766). n-Oximido-propion-acetic Acid, CH 3 C : NiO . CH 2 CO 2 H)CO,,H, melts at 131 (B. 29, R. 169). a-Oximido-butyric Acid, CH 3 . CH 2 C = (NOHJCOjH, and other rz-oximido-acids are known. a-Ox- imido-dibrom-pyroracemic Acid has been obtained in two modifications (B. 25, 904). NH (7) Hydrazipropionic Ethyl Ester, i >C(CH 3 )CO 2 C 2 H 5 , melting at 115-117 NH (T- pr. Ch. [2] 44, 554), results from pyroracemic acid and hydrazine. Mercuric oxide converts its methyl ester into a-diazopropionic methyl ester. N \ (8) a-Diazopropionic Ester, ^)C(CH 3 )CO 2 C 2 H 5 , is a yellow oil, obtained from the hydrochloride of alanine ethyl ester. (9) Phenylhydrazone-pyroracemic Acid, CH 3 C(N = NHC 6 H 5 )CO 2 H, melts with decomposition about 192, and is not only formed by the action of phenylhydrazine upon pyroracemic acid (B. 21, 984), but also in the saponification of the reaction- product from diazobenzene chloride and methyl acetoacetic ester (B. 20, 2942,3398; 21, 15 ; A. 278, 285). (10) a-Amidothiolactic Acid, CH 3 C(SH)(NH 2 ) . CO 2 H (see p. 347). /9-Ketonic Acids. In the /5-ketonic acids the ketone oxygen atom is attached to the second carbon atom, counting from the carboxyl group forward. These compounds are very unstable when free and when in the form of salts. Heat decomposes them into carbon dioxide and ketones. Their esters, on the other hand, are very stable, can be distilled with- out decomposition, and serve for various and innumerable syntheses. The /?-, f-, and 5-ketonic acids can also be considered as ketones in which an hydrogen atom has been replaced by carboxyl. In the 372 ORGANIC CHEMISTRY. /9-acids, which lose CO 2 readily, the carbonyl (CO) group and the CO 2 H group are attached to the same carbon atom (compare malonic acid). Acetoacetic Acid, Acetone-monocarboxylic Acid, CH 3 .CO.- CH 2 .CO 2 H, /5-Ketobutyric Acid [Butanon Acid]. To obtain the acid, the esters are saponified in the cold by dilute potash, or the barium salt is decomposed with sulphuric acid, and the solution shaken with ether (B. 15, 1781; 16, 830). Concentrated over sulphuric acid, acetoacetic acid is a thick liquid, strongly acid, and miscible with water. When heated, it yields carbon dioxide and acetone : CH 3 . CO . CH 2 . C0 2 H = CH 3 . CO . CH 3 -f CO 2 . Nitrous acid converts it at once into CO 2 and isonitroso-acetone (p. 326). Its salts are not very stable. It is difficult to obtain them pure, and they sustain changes similar to those of the acid. Ferric chloride imparts to them, and also to the esters, a violet-red coloration. Occasionally the sodium or calcium salt is found in urine (B. 16, 2314). The stable acetoacetic esters, CH 3 . CO . CH 2 CO 2 R, are produced by the action of metallic sodium upon acetic esters. In this reaction the sodium compounds constitute the first product. The free esters result upon treating their sodium compounds with acids, e. g., acetic acid. They are obtained pure by distillation. The acetoacetic esters are liquids, dissolving with difficulty in water. They possess an ethereal odor. They can be distilled without decomposition. The esters of acetoacetic acid, contrary to expectation, possess an add-like character. They dissolve in alkalies, forming salt-like com- pounds in which an hydrogen atom is replaced by metals. Constitution. Many reactions of acetoacetic ester are more simply explained by granting that it or its sodium compound has the constitution of [3 oxycrotonic ester, CH, . C(OH) : CH . CO 2 C 2 H 5 and CH 3 C(ONa) = CHCO 2 C 2 H 5 . However, in studying the oxymethylene bodies we learned to know derivatives possessing the atomic arrangement C(OH) : CH as represented in the /3-oxycrotonic ester formula and were then convinced that their deportment was much different from that shown by acetoacetic ester. The physical properties of the ester, its refraction (p. 65\ its molecular rotation and its behavior toward the electric waves (p. 69) have also been determined, and it has been found that they harmonize with the ketone formula, CH 3 . CO . CH 2 . CO 2 - C 2 H 5 , alone (compare, however, B. 29, 1723). The conduct of acetoacetic ester to- ward orthoformic ether is strong proof of its ketone nature. It reacts like the ketones with it, forming /3-diethoxybutyric ester and formic ester (Claisen, B. 29, 1006) : CO 2 C 2 H. . CH 2 CO 2 C 2 H 5 CH 2 2 2 a 2 I TTrVOC TT "\ 225 2 CH S CO " CH 3 C(OC 2 H 5 ) 2 -f- H . COOC 2 H 5 . However, the question whether the sodium salt does not probably have the formula CH 3 . C(ONa) : CH . CO 2 C 2 H 5 instead of CH 3 . CO . CHNa . CO 2 . C 2 H 5 , is at present still unanswered (A. 277, 162). Historical. In 1863 Geuther investigated the action of sodium upon acetic ester. Simultaneously and quite independently of Geuther, Frankland and Duppa, in con- cluding their studies upon the action of zinc and alkyl iodides upon oxalic ether (p. 331), investigated the action of sodium and alkyl iodides upon acetic ester. J. Wislicenus has contributed very materially to the explanation of the reactions here involved (1877), A. 186, 161. PARAFFIN KETONE CARBOXVLIC ACIDS. 373 As the /3-ketonic acids are so very unstable, their more stable esters are employed in their study. These can be made according to the following reactions: Formation of Acetoacetic Ester and its Homologues. (i) By the action of sodium or sodium alcoholate upon acetic ester. These reagents act similarly upon propionic ester, with the formation of a-propionyl propionic ester, CH 3 . CH 2 . CO . CH(CH 3 ).CO 2 . C 2 H 5 . However, when sodium acts upon normal butyric ester, isobutyric ester and isovaleric ester, it is not the analogous bodies which result, but oxyalkyl derivatives of higher fatty acids (B. 22, R. 22). The formation of acetoacetic ester from acetic ester is due to the elimination of alcohol from two molecules of acetic ester by the action of sodium ethylate. Claisen considers that the addition of sodium ethvlate to a molecule of acetic ester precedes the splitting-off of alcohol. A derivative of ortho-acetic acid is formed at first (p. 224) : 0,C 2 H 5 /OC 2 H 5 1CH 3 . C/ + C 2 H 5 ONa = CH 3 C^OQH 5 , which rearranges itself with a second molecule of acetic ester to sodium acetoacetic ester and alcohol : /OC 2 H 5 CH 3 . C<-OC 2 H. + CH 3 . COOC 2 H 5 = CH 3 C(ONa) : CHCO 2 C 2 H- -f 2C 2 H 5 OH. This view is based on the following facts: (i) The condensation of the two mole- cules of acetic ester can be effected, if less completely, by sodium ethylate (instead of sodium). ( 2) It has been shown in regard to certain acid esters, e.g., benzoic ethyl ester, that they really combine with sodium ethylate to yield ortho-derivatives of the kind mentioned. (3) In other condensations, manifestly analogous to the ester for- mation, "* ' OH ' Methyl Acetone 2KOH = CO V OH - Dimethyl Acetone. (i) At the same time another splitting-off takes place, by which the alkylic acetic acids, /. e. t the higher fatty acids are produced along with acetic acid (acid decomposition) : co /CH 3 _ (CH 3 )CH 2 .C0 2 K CHNa + 2NO + C 2 H 50Na = cH 3 C2 CO> C Na) : CH . CO 2 C 2 H 5 , should be ascribed to sodium acetoacetic ester (compare P- 346). (7) Aldehydes, e. g., acetaldehyde, and acetoacetic ester unite to ethidene-mono- and ethidene bisacetoacetic esters. The latter y-diketones especially are important', because by an intramolecular exit of water from CO and CH 3 they condense to keto- hydrobenzene derivatives (A. 288, 323), and with ammonia yield hydropyridine bodies. (8) Acetoacetic ester condenses similarly with orthoformic ester to the ethoxy- methylene derivative (C 6 H g O.,) : CHOC 2 H 5 , on the one hand, and on the other to the methylene derivative (CgHgOg) : CH . (C 6 H 9 O 3 K(B. 26, 2729). (9) Resorcinol and acetoacetic ester condense to /3-methylurnbelliferone (B. 29, 1794). Ethyl Acetoacetic Ester, CH 3 . CO . CH 2 . CO 2 . C 2 H 5 = C 6 - H 10 O 3 , Acetoacetic Ester, boiling at 181 (760 mm.) and 72 (12 mm.), is a pleasantly smelling liquid, of sp. gr. 1.0256 at 20. It distils over with steam. The ester is only slightly soluble in water. Ferric chlo- ride colors it violet. Boiling alkalies or acids convert the ester into acetone, carbon dioxide and alcohol. In addition to its formation by the action of sodium or sodium ethylate upon ethyl acetic ester, it results by the par- tial decomposition of acetone dicarbonic ester (see this), CO 2 C 2 H 5 CH 2 - COCH 2 CO 2 C 2 H 5 . The sodium salt, CH 3 COCHNaCO 2 C 2 H 5 or CH 3 (CONa) : CHCO 2 C 2 H 5 , crystal- lizes in long needles. The copper salt, (C 6 H 9 O 8 ) 2 Cu, is produced when a copper ace- tate solution is mixed with an alcoholic solution of acetoacetic ester and a sufficient quantity of ammonia is added. The following are some of the numerous (3 ketonic esters : Methyl Acetoacetic 32 378 ORGANIC CHEMISTRY. Ester, boiling at 169 (760 mm.). Methyl Acetoacetic Methyl Ester, CH 3 COCH- (CH 3 )CO 2 CH 3 , boils at 177 ; the ethyl ester at 187 ; Ethyl Acetoacetic Methyl Ester, CH 3 .GO. CH(C 2 H 5 )CO 2 CH 3 , boiling at 190; ethyl ester at 198. Dimethyl Acetoacetic Ester, C H 3 COC(CH 3 ) 2 CO 2 C S H 5 , boils at 184. Diethyl Acetoacetic Ester boils at 218. \\-Propyl Acetoacetic Ester boils at 208. Methyl Ethyl Acetoacetic Ester boils at 198. Propionyl Propionic Ester, Methyl Propionyl Acetic Ester, CH 3 CH 2 COCH(CH 3 ). CO 2 C 2 H 5 , boils at 196. $-Diethoxybutyric Acid, CH 3 . C(O . C 2 H 5 ) 2 CH 2 CO 2 H, is a syrupy liquid, which decomposes on the application of heat into CO 2 and acetone ortho-ethyl ether (p. 219). Its sodium salt is obtained by means of alcoholic sodium hydroxide frum /3-diethoxy-butyric ester, CH 3 . C(O . C 2 H 5 ) 2 CH 2 CO 2 C 2 H 5 , the product of the trans- position of acetoacetic ester and ortho-formic ester (B. 29, 1006). /3-Diethoxybutyric ester decomposes upon distillation into alcohol and /3-ethoxycrotonic ester (p. 363). fi-Dithioethyl-butyric Ester, CH 3 C(SC 2 H 5 ) 2 CH 2 CO 2 C 2 H 5 , see B. 19, 2810; 29, 1648. Derivatives of the /3-Ketonic Acids, containing Nitrogen. 1. Amides. Ammonia converts acetoacetic esters into /3-Amidocrotonic Esters, while the monomethyl- and monoethyl-acetoacetic ester, with the same reagent, yield the amides: Methyl Acetoacetamide, CH 3 . CO . CH(CH 3 )CO . NH 2 , melting at 73 ; Ethyl Acetoacetamide, melting at 96 (A. 257, 243). 2. Cyanacetone, Acetoacetic Nitrile, CH 3 . CO . CH 2 . CN, boiling at 120 to 125, results from the interaction of chloracetone and potassium cyanide (B. 25, 2679) ; from imidoacetonitrile and hydrochloric acid, and from a-methyl isoxazole (p. 327). 3. Imidoacetoacetic Nitrile, CH 3 . C(: NH)CH 2 CN, melting at 52, H produced by the polymeiization of acetonitrile with metallic sodium i J. pr. Ch. [2] 52, 81). For the action of aniline, hydrazine, phenylhydrazine andsemi-carbazide, hydroxyl- amine, nitrous acid, nitric oxide, diazomethane, benzene diazosalts, urea and amidines upon 3-ketonic esters, compare the reactions 5-12, pp. 375, 376. 4. Dinitrocaproic Acid, a-Dimethyl-/?-dinitrobutyric Acid, CH 3 . C(NO 2 ) 2 . C- (CH,) CO 2 H, melts with decomposition at 215 C. It results from the prolonged boiling of camphor with nitric acid (B. 26, 3051). Halogen Substitution Products of the /3-Ketonic Esters. Chlorine alone or in the presence of sulphuryl chloride acting upon acetoacetic ester replaces the hydrogen atoms both of the CH 2 and CH 3 groups by chlorine. The hydrogen of the CH 2 group is first substituted, but in the case of bromine the substitution begins with the CH 3 group (A. 278, 61). a-Chlor-acetoacetic Ester, CH 3 . CO . CHC1 . CO 2 . C 2 H 5 , with a very pene- trating odor, boils at 109 (10 mm.). a-Brom-acetoacetic Ester, CH 3 . CO . CHBr. CO 2 . C 2 H 5 , boils at 9O-ioo (20 mm.). It is formed when bromine acts upon copper acetoacetic ester. HBr gradually (B. 27, 3168) changes it to y-brom-acetoacetic ester, CH 2 Br.CO. CH 2 . - CO 2 C 2 H 5 , melting at 125 (8-10 mm.) (B. 29, 1042). The constitution of these two bodies has been established by condensing them with thiourea to the corresponding thiazole derivatives. aa-Dichlor-acetoacetic Ester, CH 3 . CO . CC1 2 . CO 2 . C 2 H 5 , is a pungent-smelling liquid, boiling at 205. Heated with HC1 it decomposes into o-dichloracetone, CH 3 . CO . CHC1 2 , alcohol and CO 2 ; with alkalies it yields acetic and dichloracetic acids. aa-Dibrom- acetoacetic Ester is a liquid. It yields a dioxime, CH 3 C(NOH)- C(NOH)CO 2 C 2 H 5 , melting at 142. ay-Dibrom-acetoacetic Ester, CH 2 Br.CO.- CHBr. CO 2 C 2 H 5 , melts at 45-49- Bromine converts the mono-alkylic acetoacetic esters into monobrom- and dibrom- derivatives. According to Demarcay (B. 13, 1479, l8 7) tne rnonobrom-bodies, when heated alone or with water, split off ethyl bromide and yield peculiar acids; thus, brom-methyl acetoacetic ester gave Tetrinic Acid or Methyl Tetronic Acid, L.tVULlNIC ACID. 379 while brometbyl acetoacetic ester yielded Pentinic Acid or Ethyltetronic Acid (L. WoliT, A. 291/226): CO . CH 2 Br -C 2 H 5 P.r COCH 2 C(OII)CH 2 CH 3 . CH . CO . O . C 2 II 5 ~ *~ CH 3 . CH . CO > * CH 3 . CH - CO > Tetrinic Acid = Methyl-tetronicAcid. These acids will be discussed later as lactones of oxy-ketonic acids, together with the oxidation products of triacid alcohols. The dibrom-derivatives treated with alcoholic potash yield oxy-tetrinic acid, oxy- pentinic acid, etc. Gorbow (B. 21, R. 180) found them to be homologues of fumaric acid. Oxy-tetrinic acid is mesaconic acid (see thisj ; while oxypentinic acid is ethyl fumaric acid (see this), etc. f-Ketonic Acids. These acids are distinguished from the acids of the /3-variety by the fact that when heated they do not yield CO 2 , but split off water and pass into unsaturated ^-lactones. They form ^-oxyacids on reduction, which readily pass into saturated ^-lactones. An interesting fact in this connection is that they yield remarkably well crystallized acetyl deriva- tives when treated with acetic anhydride. This reaction, as well as the production of unsaturated ^-lactones, on distillation, argue for the view that the f-ketonic acids are f-oxylactones : CH 3 .CO.CH 2 .CH 2 CH 3 .C(OH).CH,.CH 2 CH 3 COO O - CO CH 3 .C:CH.CHj 1 |8 | or - $- \/ I - > I COOH O CO CH 3 .C.CH 2 .CH 2 O - CO. Lsevulinic Acid Acetyl-laevulinic a-Angelica Acid Lactone. Laevulinic Acid, /2-Aceto-propionic Acid, C 5 H 8 O 3 = CH 3 . - CO . CH 2 . CH 2 . CO 2 H, or CH 3 . C(OH) . CH 2 . CH 2 COO, melts at 32.5; boils at 144 (12 mm,), 239 at the ordinary pressure, when slight decomposition ensues. ^-Ketovaleric Acid, or ^-Oxovaleric Acid [4-Pentanon Acid] is isomeric with methyl acetoacetic acid, which may be designated a-aceto-propionic acid. Laevulinic acid can be obtained from the hexoses (see these) on boiling them with dilute hydrochloric or sulphuric acid. It is more easily obtained from laevulose hence the name than from dextrose. It is prepared on heating cane-sugar or starch with hydrochloric acid (B. 19, 707, 2572; 20, 1775; A. 227, 99). Its constitution is evident from its indirect synthesis: sodium acetoacetic ester and chloracetic ester yield aceto-succinic ester, which, on boiling with hydrochloric acid or baryta water, loses CO 2 and passes into laevulinic acid (Conrad, A. 188, 223): CH 3 .CO.CHNa ciCH 2 cOvCoH 5 CH3.CO.CH.CHo.CO,QH 5 HCI CO.C.H co.cH 5 co 2 380 ORGANIC CHEMISTRY. It is furthermore obtained by the action of concentrated H 2 SO 4 upon CO 2 H O CO methyl-glutolactonic acid, I ; by the oxidation of its CH 3 -C-CH 2 CH 2 corresponding /9-acetopropyl alcohol (p. 318), and by the oxidation of methyl heptenone (p. 221), of linalol and geraniol, two bodies belong- ing to the group of olefine terpenes. Laevulinic acid dissolves very readily in water, alcohol and ether, and sustains the following transformations: (i) By slow distillation under the ordinary pressure it breaks down into water and a- and /?- angelica lactones (p. 362). (2) When heated to 150-200 with hydri- odic acid and phosphorus, laevulinic acid is changed to n-valeric acid. (3) By the action of sodium amalgam sodium ^-oxyvalerate is pro- duced. The acid liberated from this becomes ^-valerolactone. (4) Dilute nitric acid converts laeviilinic acid partly into acetic and malonic acid and partly into succinic acid and carbon dioxide. (5) Bromine converts the acid into substitution products, p. 381. (6) lodic acid changes it to bi-iodo-acetacrylic acid. (7) P 2 S 3 converts it into thioto- lene, C 4 H 3 S . CH 3 . For the behavior of Isevulinic acid with hydroxylamine and phenylhydrazine consult the paragraph relating to the nitrogen derivatives of the y-ketonic acids. Nucleus- synthetic Reactions ; (8) Prussic acid and laevulinic acid yield the nitrile of lactonic acid: CH 3 . C(CN)CH 2 . CH 2 COO, see methyl oxyglutaric acid. (9) Benzaldehyde and laevulinic acid condense in acid solution to fi-benzal-ltzvulinic acid, and in alkaline solution to &-benzal-lcemdinic acid (A. 258, 129 ; B. 26, 349). Lsevulinic Acid Derivatives. The calcium salt, (C 5 H 7 O 3 ) 2 Ca -f- 2H 2 O. The silver salt, C 5 H 7 O 3 Ag, is a characteristic, crystalline precipitate, dissolving in water with difficulty. The methyl ester, C 5 H 7 (CH 3 )O 3 , boils at 191, the ethyl ester at 200. CH 3 COO, .O . CO Acetyl Lcevulinic Acid, y-Acetoxyl-y-valerolactone, \^""^ i^ , is particularly noteworthy. It melts at 78, and is formed from laevulinic acid and acetic anhydride; from silver Isevulinate and acetyl chloride; from laevulinic chloride and silver acetate, as well as from a-angelica lactone and acetic acid. The last method of formation, as well as the formation of - and /3-angelica lactone by aceto- laevulinic acid are most easily understood upon the assumption that the constitution is really as indicated in the formula shown above (A. 256, 314). __ _ ( Lavulinic Chloride, y-Chlorvalerolactone, CH 3 . CC1 . CH 2 . CH 2 . COO, boiling at 80 (15 mm.), is produced by the addition of HC1 to a-angelica lactone, and by the action of acetyl chloride upon laevulinic acid (A. 256, 334). Lavulinamide, y-Amidovalerolactone, CH 3 . C(NH 2 ) . CH 2 . CH 2 COO, has been obtained from loevulinic ester, and from a-angelica lactone and ammonia (A. 229, 249). Homologous Laevulinic Acids are obtained from the homologues of aceto- succinic ester : $-Methyl-lCH .- CO 2 H, boils at 248. a-Ethyl Leeuuiinic Acid, CH 3 CO . CH 2 CH(C 2 H 6 ) S . CO 2 H, boils at 250-252. HOMOLOGOUS UEVULINIC ACIDS. 381 Mesitonic Add, a- Dimethyl Uevulinic acid, CH 3 . CO . CH 2 C(CH 3 ) 2 CO 2 H, melting at 74 and boiling at 138 (15 mm.), results when the addition product of hydrochloric acid and mesityl oxide is treated with potassium cyanide, and the nitrile then saponified with hydrochloric acid (A. 247, 99), as well as by heating mesitylenic acid with hydrochloric acid (B. 25, R. 905). Nitric acid oxidizes mesitonic acid to dimethyl malonic acid. 6 -Dimethyl Lavulinic Add, (CH,) 2 CH . CO . CH 2 . CH 2 . CO 2 H, melting at 40, is produced when sodium malonic ester, from the transposition product of y-brom- dimethyl acetoacetic ester, is heated with dilute sulphuric acid (B. 30, 864). Ilomolimulinic Add, d-methyl laevulinic acid, CH 3 . CH 2 . CO . CH 2 . CH 2 . CO 2 H, melting at 32, is obtained, together with an oxycaprolactone, from /8; -dibromcaproic ac.d (A. 268, 69). 6-Dim(th>l LavuKnu Add, (CH 3 ),CH . CO . CH 2 . CH 2 . CO 2 H, melting at 41, is prepared by the action of a soda solution upon isoheptenic dibromide (p. 284) (A. 288, 183). Halogen > -Ketonic Jkc.\&s.a-Brom-lCC1 : CC1 . CO 2 H, melting at 83-84 (B. 26, 511), and other chlorinated ace'yl-acrylic, and acetyl methyl acrylic acids (B. 26, 1670), are formed from the decomposition of benzene derivatives which have previously been chlorin ated. fi-Acetyl-dibrom-acrylic Acid, CH 3 . COCBr : CBr. COOH, or CH 3 . C(OH)CBr: CBrCOO, melting at 78, results upon treating a tribromthiotolene with nitric acid. Its remarkably low conductivity bespeaks its lactone formula (B. 24, 77; 26, R. 16). j Ketonic Acids. Chlorinated (?-ketonic acids have been obtained from the ketochlorides of resorcinol and orcinol, e. g., trichloracetyl-trichlorcrotonic acid, CV1 3 . CO . CC1 : CH . CC1 2 . CO a H, see B. 26, 317, 504, 1666. CARBONIC ACID AND ITS DERIVATIVES. The acid only exists in its salts and esters, and may be regarded as oxy formic acid, HO. CO. OH. Its symmetrical structure d s- tinguishes it, however, from the other oxy-acids containing three atoms of oxygen. It is a weak dibasic acid and constitutes the transition to the true dibasic dicarboxylic acids hence it will be treated separately. On attempting to liberate the hydrated acid from carbonates by a stronger acid, it breaks down, as almost always happens, when two hydroxyl groups are attached to the same carbon atom. A molecule of water separates, and carbon dioxide, CO 2 , the anhydride of carbonic acid, is set free. The carbonates recall the sulphites in their deport- ment, and carbon dioxide reminds us of sulphur dioxide or sulphurous anhydride. Every carbon compound, containing an atom of carbon in double union with an oxygen atom, may be regarded as the anhydride of a dihydroxyl body corresponding to it. The hydrate formula, C = O- (OH),, of carbonic acid may be viewed as the formula of an anhydride of the compound C(OH) 4 . Of course a compound of this form will be as unstable as orthoformic acid, HC(OH) 3 (p. 224). However, esters derived from the formula C(OH\, can actually be prepared; they are the orthocarbonic esters. In a broader sense, all methane derivatives, in which the four hydrogen atoms have been replaced by four univalent elements or residues, must be considered as derivatives of orthocarbonic acid, e. g., tetrachlor-, tetrabrom-, tetra-iodo-, and tetrafluormethane. From this point of view tetrachlormethane is the chloride of orthocarbonic acid. These compounds, together with chloropicrin, CC1 3 NO 2 , bromopicrin, CBr 3 NO ? , brom-nitroform, CBr- (XO 2 ) 3 , and tetranitromethane, C(NO,) 4 , will be discussed later as derivatives of orthocarbonic acid. The carbon tetramide is not known. Ammonia appears most frequently in the reactions where it might well be expected, and also guanidine, which sustains the same 384 ORGANIC CHEMISTRY. relation to the hypothetical carbon tetramide the amide of ortho- carbonic acid, as metacarbonic acid bears to the ortho-acid : OH ,011 "\OH ~\ZS \ru* OH C CO 2 and CH 3 . CO 2 H. 2 The /9-ketonic acids deport themselves similarly (p. 371), e.g. : Acetoacetic Acid, CH 3 . CO . CH 2 . CO 2 H > CO 2 and CH 3 . CO . CH 3 . Monocarboxylic acids or their alkali salts can be deprived of CO 2 upon heating them with NaOH, when it disappears as CO 3 Na 2 (p. 81): CH 3 . C0 2 Na + NaOH = CO 3 Na 2 -f CH 4 . The electric current acting upon concentrated solutions of the alkali salts of carboxylic acids splits off carbon dioxide (p. 83), e. g.: 2CH 8 . CO 2 K - > O-lgH+jCO^ and 2K. DERIVATIVES OF CARBONIC ACID. 385 The calcium salts of many carboxylic acids are decomposed by heat with the production of calcium carbonate and ketones (p. 188), e. g. : (CH 3 CO 2 ) 2 Ca > CO 3 Ca + CH 3 . CO . CH 3 . These and similar reactions, in which CO 2 is easily split off from organic compounds, are of the first importance in the production of the different classes of compounds. In contrast to the splitting-off of CO 2 in certain reactions we have its absorption by certain organic alkali derivatives: nucleus-syntheses, in which carboxylic acids are produced : CH 3 Na + CO 2 = CH 3 . CO 2 Na (p. 240). C 6 H 5 ONa + C0 2 = C 6 H 4 <2 Na (compare salicylic acid). Esters of Metacarbonic Acid, or ordinary Carbonic Acid. The primary esters of carbonic acid are not stable in a free con- dition. Dumas and Peligot obtained the barium salt of methyl carbonic acid on conduct- ing carbonic acid into a methyl alcohol solution of anhydrous baryta (A. 35, 283). x~v /" TT The potassium salt of Ethyl Carbonic Acid, CO^Q^r 2 5 > separates in pearly scales on adding CO 2 to the alcoholic solution of potassium alcoholate. Water decomposes it into potassium carbonate and alcohol. The neutral esters appear (i) when the alkyl iodides act on silver carbonate : C0 3 Ag 2 + 2C 2 H 5 I = C0 3 (C 2 H 5 \ + 2AgI ; also (2) by treating esters of chlorformic acid with alconols, whereby mixed esters may also be obtained : C0 <0. CH 3 + C * H 5 ' OH = C0 <8 : CH 1 . 6 + HCL Methyl-ethyl Carbonate. It is also true, that, with application of heat, the higher alcohols are able to expel the lower alcohols from the mixed esters : C0 <0 i CH, 5 + C ' H 5 OH = C0 <0 '. C 2 H 6 5 + CH 3H. Methyl Ethyl Ester Diethyl Ester. Hence, to obtain the mixed ester, the reaction must occur at a lower temperature. As regards the nature of the product, it is immaterial as to what order is pursued in introducing the alkyl groups, i, e., whether proceeding from chlorformic ester, we let ethyl alcohol act upon it, or reverse the case, letting methyl alcohol act upon ethyl chlorformic ester; the same methyl ethyl carbonic acid results in each case (B. 13, 241 7). This is an additional confirmation of the like valence of the carbon affinities, already proved by numerous experiments made with that direct object (with the mixed ketones) in view. The neutral carbonic esters are ethereal smelling liquids, dissolving readily in water. Excepting dimethyl and the methyl-ethyl ester, all 33 386 ORGANIC CHEMISTRY. are lighter than water. With ammonia they first yield carbamic esters and then urea. When they are heated with phosphorus pentachloride, an alkyl group is eliminated, and in the case of the mixed esters this is always the lower one, while the chlorformic esters constitute the product : C0 <0 : C 2 H 3 5 + PC1 ' = C0 <0. C 2 H 5 + PC1 ' + CH * C1 - Methyl Carbonic Ester, CO 3 (CH 3 ) 2 , is produced from chlorformic ester by heat- ing with lead oxide. It boils at 91. The methyl ethyl ester, CO 3 <~ T| , boils ^2^5 at 109. The ethyl ester, CO 3 (C 2 H 5 ) 2 , is obtained from ethyl oxalate, C 2 O 4 (C 2 H 5 ) 2 , on wanning with sodium or sodium ethylate (with evolution of CO 2 ). It boils at 126. The methyl propyl ester, CO 3 (CH 3 )(C 3 H 7 ), boils at 131. The ethylene ester, CO 3 C 2 H 4 , glycol carbonate, obtained from glycol and COC1 2 , melts at 39 and boils at 236. Derivatives of Orthocarbonic Acid (p. 383). Orthocarbonic Ester, C(O. C 2 H 5 ) 4 (1864 Bassett, A. 132, 54), may be regarded as the ether of the tetrahydric alcohol or normal carbonic acid, C(OH) 4 . It is produced when sodium ethylate acts on chloropicrin : CC1 3 (N0 2 ) + 4 C 2 H 5 . ONa = C(O . C 2 H 5 ) 4 + 3 NaCl + NO 2 Na. It is a liquid with an ethereal odor, and boils at 158-159. When heated with ammonia it yields guanidine and alcohol. The propyl ester, C(O.C 3 H 7 ) 4 , boils at 224, the isobutyl ester at 250, and it seems the methyl ester can not be prepared (A. 205, 254). The tetrahalogen substitution products of methane appear to be the halides corresponding to Orthocarbonic acid. They bear the same relation to the Orthocarbonic esters that chloroform, bromoform and iodoform sustain to the orthoformic esters. However, the ortho- carbonic acid esters have not yet been prepared from the tetrahalogen substitution products of methane. Several nitrohalogen methanes and tetranitro-methane will be described here. Methane Tetrahalogen Substitution Products : Tetraftuormethane, Carbon Tetrafluoride, CF 4 , is a colorless gas, condensable by pressure. It is remarkable that this body belongs to that small class of carbon derivatives which can be directly prepared from the elements. Finely divided carbon, e. g. , lamp black, combines directly with fluorine, with production of light and heat, and yields CF 4 . Tetrachlormethane or Carbon Tetrachloride, CC1 4 , is formed (i) by the action of chlorine upon chloroform in sunlight, or upon the addition of iodine, and (2) by action of Cl upon CS 2 at 20-40, C 2 C1 4 and C 2 C1 6 being formed at the same time (B. 27, 3160); (3) upon heating CS 2 with S 2 C1 2 in the presence of small quantities of iron : CS 2 -f 2S 2 C1 2 = CC1 4 -f 6S (D. R. P. 72999). It is a pleasant-smelling liquid, boiling at 76. Its specific gravity is 1.631 at o. At 30 it solidifies to a crystalline mass. It is an excellent solvent for many substances, and is made upon a technical DERIVATIVES OF CARBONIC ACID. 387 scale. Heated with alcoholic KOH, it decomposes according to the following equation : CC1 4 + 6KOH = K 2 C0 3 + 3H 2 + 4KC1. CC1 4 sustains the same relation to carbonic acid that chloroform does to formic acid. When the vapors are conducted through a red-hot tube, decomposition occurs; C 2 C1 4 and C 2 C1 6 are produced. This is an interesting reaction because, as we learned under acetic acid (p. 274), it plays a part in the first synthesis of this long-known acid. When carbon tetra- chloride is digested with phenols and sodium hydroxide, phenol carboxyhc acids are produced. Tetrabrommethane, CBr 4 , obtained by the action of brom-iodide upon bromo form or CS 2 , crystallizes in shining plates, melting at 92.5, and boiling, with but little decomposition, at 189. Tetraiodomethane, CI 4 , carbon iodide, is formed when CC1 4 is heated with aluminium iodide. It crystallizes from ether in dark red, regular octahedra, of specific gravity 4.32 at 20. On exposure to air it decomposes into CO 2 and I. Heat accelerates the decomposition. Nitro-derivatives of Orthocarbonic Acid. Nitrochloroform, C(NO 2 )C1 3 Chloropicrin, trichlor-nitrome- thane, is frequently produced in the action of nitric acid upon chlor- inated carbon compounds (chloral), and also when chlorine or bleach- ing powder acts upon nitro-derivatives (fulminating mercury, picric acid and nitromethane; also from fulminating mercury, p. 238). In the preparation of chloropicrin, 10 parts of freshly prepared bleaching powder are mixed to a thick paste with cold water and placed in a retort. To this is added a saturated solution of picric acid, heated to 30. Usually the reaction occurs with- out any additional heat, and the chloropicrin distils over with the aqueous vapor (A. 139, "I). Chloropicrin is a colorless liquid, boiling at 112, and having a spe- cific gravity of 1.692 at o. It possesses a very penetrating odor that attacks the eyes powerfully. It explodes when rapidly heated. When treated with acetic acid and iron filings it is converted into methyl- amine : CC1 3 (N0 2 ) + 6H 2 = CH,.NH a + 3HC1 + 2H 2 O. Alkaline sulphites change it to formyl trisulphonic acid, ammonia to guanidine, and sodium ethylate to orthocarbonic ester (p. 386). Bromopicrin, CBr 3 (NO 2 ), melting at -(- 10, can be distilled under greatly re- duced pressure without decomposition, and is formed, like the preceding chloro-com- pound, by heating picric acid with calcium hypobromite (calcium hydroxide and bromine), or by heating nitromethane with bromine (p. 157). It closely resembles chloropicrin. Brom-nitroform, C(NO 2 ) 3 Br, Brom-trinitromethane, is produced by permitting bromine to act for several days upon nit reform exposed to sunlight. The reaction takes place more rapidly by adding bromine to the aqueous solution of the mercury salt of nitroform. In the cold it solidifies to a white crystalline mass, fusing at -f-l2. It volatilizes in steam without decomposition. 388 ORGANIC CHEMISTRY. Tetranitromethane, C(NO 2 ) 4 , results on heating nitroform with a mixture of fuming nitric acid and sulphuric acid. It is a colorless oil that solidifies to a crystalline mass, fusing at 13. It is insoluble in water, but dissolves readily in alcohol and ether. It is very stable, and does not explode on application of heat, but distils at 126. CHLORIDES AND AZIDES OF CARBONIC ACID. Two series of salts, two series of esters, and two chlorides can be obtained theoretically from a dibasic acid : rr> ..OH rn .-O . C 2 H 5 pp-^OCgHg ro^^ rn^-'d as, light, and yewdw, to produce. It is also formed by conducting CO into boiling SbCl 5 , and by oxidizing chloroform by air in the sunlight or with chromic acid : 2CHC1 3 + CrO 3 -f 2O = 2COC1 2 -f H 2 O -f CrO 2 Cl 2 . Phosgene is most conveniently prepared from carbon tetrachloride (100 c.c.), and 80 per cent. " Oleum " (120 c.c.), a sulphuric acid con- taining SO 3 (B. 26, 1990), when the SO 3 is converted into pyrosul- phuryl chloride, S 2 O 5 C1 2 . SULPHUR DERIVATIVES OF ORDINARY CARBONIC ACID. 389 Technically it is made by conducting CO and C1 2 over pulverized and cooled bone charcoal (Paternd). Instead of condensing the gas it may be collected in cooled benzene. Carbonyl chloride is a colorless gas with suffocating odor, and on cooling is condensed to a liquid. Transpositions : (i) Water at once breaks it up into CO 2 and 2HC1. (2) Alcohols convert it into chlor- carbonic and carbonic esters. (3) With ammonium chloride it forms urea chloride. (4) Urea is produced when ammonia acts upon it. Phosgene has been employed in numerous nucleus-synthetic reactions, e. -., it has been used in the technical way for the preparation of di- and tri-phenylmethane dye-stuffs (see tetra-methyl-diamido-benzo- phenone). Carbon Oxychlorbromide, COClBr, boiling at 35~37, and carbon oxybromide, COBr 2 , boiling at 63-66, are formed when COC1 2 and PBr 3 interact at 150 (B. 28, R. 148). The nitrogen carbonic esters and nitrogen carbon monoxide correspond to the chlorcarbonic esters. Nitrogen Carbonic Methyl Es/er, Azide Carbonic Ester, N 3 . CO 2 C 2 H 5 , boiling at 102, is a transparent liquid, produced by the action of chlorcarbonic ester upon ammonium hydronitride (J. pr. Ch. [2] 52, 461). Nitrogen Carbon Monoxide, CO(N 3 ) 2 , consists of explosive crystals, very volatile, with a penetrating and stupefying odor, recalling both hydronitric acid and carbon oxychloride. It is produced when sodium nitrite acts upon the hydrochloride of carbohydrazide : CO(NH . NH 2 . HC1) 2 -f 2N0 2 Na = CO(N 3 ) 2 + 2 NaCl + 4 II 2 O. Its aqueous solution decomposes into carbon dioxide and hydrazoic acid (B. 27, 2684 ; J. pr. Ch. [2] 52, 282). SULPHUR DERIVATIVES OF ORDINARY CARBONIC ACID. By supposing the oxygen in the formula CO(OH) 2 to be replaced by sulphur, there result : Thiocarbonic Acid ,, rQ ^OH Sulphocarbonic Acid Carbon-monothiol Acid 2 ' ^ b \QH Thion-carbonic Acid Dithiocarbonic Acid r c^SH Sulphothiocarbonic Acid Carbondithiol Acid ^OH Thion-carbon-thiol Acid OTT 5. CS is obtained (i) from xanthic esters and alcoholic potash (p. 392), and (2) in the union of carbon dioxide with potassium mercaptide. It crystallizes in needles and prisms, which Teadily dissolve in water and alcohol. l"V ^ T T With ethyl iodide the potassium salt forms ethyl thioxy carbonate, COC 2 H 4 , melts at 39.5. When oxidized with dilute nitric acid the ester becomes ethylene- dithiocarbonic ester, COS 2 :C 2 H 4 (A. 126, 269). Chlorides of the Sulpho-carbonic Acids : Thiophosgene, Thiocarbonyl Chlo- ride, CSC1 2 , boiling at 73, sp. gr. 1.508 (15), is produced when chlorine acts upon carbon disulphide, and when the latter is heated with PC1 5 in closed tubes to 200 : CS., + PC1 5 = CSC1 8 -f PC1 3 S. It is most readily obtained by reducing perchlormethylmercaptan, CSC1 4 (p. 393), with stannous chloride, or tin and hydrochloric acid (B. 20, 2380; 21, 102) : CSC1 4 4- SnCl 2 = CSC1 2 -f SnCl 4 . This is the method employed for its production in large quantities. It is a pungent, red-colored liquid, insoluble in water. On standing exposed to sunlight it is converted into a polymeric, crystalline compound, C 2 S 2 C1 4 = Cl . CS . - S . CC1 3 , methyl perchlor-dithioformate, which melts at 116, and at 180 reverts to the liquid body (B. 26, R. 600). Water decomposes thiophosgene and 2HC1, while ammonia converts it into ammonium sulphocyanide (p. 422). AMIDE DERIVATIVES OF CARBONIC ACID. 393 Thiocarbonyl chloride converts secondary amines (i molecule) into dialkyl sulpho- carbamic chlorides : CSC1, + NH(C 2 H 5 )C 6 H. = A second molecule of the amine produces tetra-alkylic thioureas (B. 21, 102). Benzene, in the presence of A1C1 3 , yields thiobenzophenone. Phosgene and thiophosgene, when acted upon by alcohols and mercaptans, yield sulphur derivatives of chlorcarponic ester (p. 389). Chlorcarbon-thiol Ethyl Ester, Chlorthiocarbonic Ethyl Ester, Chlorperthiocarbonic Ethyl Ester, ....... C1.CSSC 2 H 5 Perchlorsulpho-thiocarbonic Methyl Ester, . . , . Cl . CSSCC1 3 (see thiophosgene). SULPHUR DERIVATIVES OF ORTHOCARBONIC ACID. Perchlormethyl Mercaptan, CC1 8 . SCI, boiling at 147, results from the action of chlorine upon CS 2 . It is a bright yellow liquid. Stannous chloride reduces it to thiophosgene. Nitric acid oxidizes it to Trichiormethyl Sulphonic Chloride, CC1 3 . SO 2 C1, melting at 135 and boiling at 170, which can be made by the action of moist chlorine upon CS 2 . It is insoluble in water, but dissolves readily in alcohol and ether. Its odor is like that of camphor, and excites tears. Water changes the chloride to Trichiormethyl Sulphonic Acid, CC1 3 . SO 3 H -f- H 2 O, consisting of deliquescent crystals. By reduction it yields CHC1 2 . SO 3 H, dichlormethyl sulphonic acid, CH 2 - Cl . SO 3 H, monochlormethyl sulphonic acid, and CH 3 . SO 3 H (p. 152). Diethyl Sulphone Dibrom- methane, CBr 2 (SO 2 C 2 H 5 ) 2 , melting at 131, x&&diethyl- sulphone di-iodomethane, CI 2 (SO 2 C 2 H 5 ) 2 , melting at 176, are formed when bromine 'acts upon diethyl sulphone methane, and iodine in potassium iodide, or iodine alone upon diethyl sulphone methane potassium (B. 30, 487). Potassium Di-iodomethane Disulphonate, CI 2 (SO 3 K) 2 , and Potassium lodomethane Disulphonate, CHI(SO 3 K) 2 , are produced when potassium diazomethane disulpho- nate is decomposed with iodine and with hydrogen iodide. Sodium amalgam reduces both bodies to methylene disulphonic acid (p. 204). Potassium Methanoltrisulphonate, HO . C(SO 3 K) 3 . H./3, results when the addition product of acid potassium sulphite and potassium diazomethane disulphonate is boiled with hydrochloric acid. A like treatment of potassium sulph-hydrazimethylene tri- sulphonate will also yield it (B. 28, 2378). AMIDE DERIVATIVES OF CARBONIC ACID. Carbonic acid forms amides which are perfectly analogous to those of a dibasic acid e. g., oxalic acid (p. 432) : NH NH NH NH Carbamic Acid Urethane, Urea Chloride, Urea, Carbamic Ester Carbamic Chloride Carbamide CONH, CONH 2 CO.NH 2 COOH CO . O . C 2 H 5 CO . NH 2 Oxamic Acid Oxamic Ester Oxamide. Carbamic Acid, H. 2 N . CO . OH, Amidoformic Acid, is not known in a free state. It seems its ammonium salt is contained in commercial 394 ORGANIC CHEMISTRY. ammonium carbonate, and is prepared by the direct union of two molecules of ammonia with carbon dioxide. It is a white mass which breaks up at 60 into 2NH 3 andCO 2 , but these combine again upon cool- ing. Salts of the earth and heavy metals do not precipitate the aqueous solution ; it is only after warming that carbonates separate, when the carbamate has absorbed water and becomes ammonium carbonate. When ammonium carbamate is heated to 130-140 in sealed tubes, water is withdrawn and urea, CO(NH 2 ) 2 , formed. The esters of carbamic acid are called urethanes ; these are obtained (i) by the action of ammonia at ordinary temperatures upon carbonic esters : C0 <0 .' C 2 H 5 5 + NH 3 = C0 <0 H C 2 H 3 + C * H 5 ' OH ' and (2) in the same manner from the esters of chlorcarbonic and cyan- carbonic acids : C0 <0 . C 2 H 5 + 2NH = CO CO < N C 2 H 5 + 2NH = CO yl ester melts at 53 and boils at 195. The ally! ester, CO(NH 2 ) . O . C 3 H 5 , is a solid, melting at 21 and boiling at 204. Acetyl Urethane^ CH 3 . CON H . CO 2 C 2 H 5 , is obtained from acetyl chloride and urethane. It melts at 78 and boils at 130 (72 mm. ). Hydrogen in it can be re- URETHANE. 395 placed by sodium. Alkyl iodides acting upon the sodium compound produce : alkylic acetyl urethanes (B. 25, R. 640). When heated to 150 with urea, acetyl urethane ;nto acetguanamide, or methyl dioxytriazine, and with hydrazine it yields the triazolones (A. 288, 318). The esters of these alky lized carbamic acids are formed, like the ure- thanes, by (i) the action of carbonic or (2) chlorcarbonic esters upon amines; and (3) on heating isocyanic esters (p. 418) with the alcohols to 100 : CO : N . C 2 H 5 + C 2 H. . OH = CO<*J H C ' > H 5 ; also (4) by the interaction of the chlorides of alkyl urea and the alco- hols; (5) when alcohols act upon acid azides (p. 163). Methyl Etho-carbamic Ester, CH 3 . HN . CO . O . C 2 H 5 , boils at 170 (B. 28, 855). Ethyl Etho-carbamic Ester, (C 2 H 5 )HN . CO . O . C 2 H 5 , boils at 175. Ethylene Urethane, C 2 H 5 . OCO . NHCH 2 . CH 2 NHCO. O . C 2 H 5 , from ethy- lene diamine and C1CO 2 C 2 H 5 (B. 24, 2268), melts at 113. Derivatives of carbamic acid with divalent radicals are produced by the union of esters of the acid with aldehydes : Ethidene Diurethane, CH 3 . CH(HN . CO. O . C 2 H 5 ) 2 , from urethane and acetaldehyde, crystallizes in shining needles, melting at 126 C. (B. 24, 2268). - Chloral Urethane, CC1 3 . CH<^jj^ PQ Q r u > from urethane and chloral, melts at 103. Acid anhydrides convert it into Trichlorethidene Urethane, CC1 3 .- CH : N . COOC 2 H 5 , melting at 143 (B. 27, 1248). Urethane Acetic Acid, CO 2 H . CH 2 NHCO 2 C 2 H 5 , is produced on evaporating urethane acetic ester, C 2 H 5 OCO . CH 2 . NH . CO 2 C 2 H , with hydrochloric acid. The acid melts at 68 ; the ester melts at 24.5-27 and boils at 45 (22 mm.) ; see nitra- mine acetic acid, p. 361 (B. 29, 1681). Nitrosourethane, NO . NH . CO 2 C 2 H 5 , melts at 51 with decomposition. It forms on reducing ammonium nitrourethane with glacial acetic acid and zinc dust (A. 288, 34)- Nitrosomethyl Urethane, CO 2 C 2 H 5 N<^ T Q 3 , from methyl urethane and nitrous acid, is a liquid which yields diazomethane when it is digested with methyl alcoholic potash (B. 28, 855). Nitrocarbamic Acid, NO 2 . NH . CO 2 H, when liberated by sulphuric acid from its potassium salt, surrounded by ice, breaks down into nitramide, NO 2 . NH 2 , melting at 72-85. and carbon dioxide. The nitramide is extracted by ether. Potassium Nitrocarbamate, NO 2 . NH . CO 2 K, consisting of delicate, white needles, is produced when methyl alcoholic potash is allowed to act upon potassium nitrourethane. Nitroureihane, NO 2 \HCO 2 C 2 H 5 , melting at 64, is produced when ethyl nitrate acts upon a cooled sulphuric acid solution of urethane. It dissolves readily in water, and very easily in ether and alcohol, but very sparingly in ligroine. It has a strong acid reaction. Its salts are neutral in their reaction. Ammoniiim Nitrourethane, NO 2 N(NH 4 )CO 2 C 2 H 5 . Potassium Nitrourethane, NO 2 NKCO 2 C 2 H 5 (J. Thiele and A. Lachmann, A. 288, 267). Methyl ^ 7 it>-o^lrethane, XO. 2 N(CH 3 )CO 2 C 2 H 5 , is a colorless oil with an agreeable odor. It is formed when methyl iodide and silver nitrourethane interact, and also from methyl urethane. Ammonia decomposes it into methyl nitramine, p. 171. Urea Chlorides, Carbamic Acid Chlorides, are produced by the interaction of phosgene gas and ammonium chloride at 400 (B. 20, 396 ORGANIC CHEMISTRY. 858 ; 21, R. 293) ; by action of COC1 2 upon the hydrochlorides of the primary amines at 260-270, and also upon the secondary amines in benzene solution : COC1 2 + NH 3 . HC1 = Cl . CO . NH 2 -f 2HC1. Urea Chloride, Carbamic Acid Chloride, Chlorcarbonic Amide, Cl . CONH 2 , melts at 50 and boils at 61-62, when it dissociates into hydrochloric acid and iso- cyanic acid, HCNO. The latter partly polymerizes to cyameltde. Urea chloride suffers a like change on standing. Carbamazide, (p. 405) and nitrous acid. Water decomposes it into CO 2 , NH 3 , and N 3 H (J. pr. Ch. [2] 5 2, 467). Mono-alky I Urea Chlorides : Cl Ethyl Urea Chloride, CO<^jj r H ' a ^ so obtained from ethylisocyanate and Cl hydrochloric acid, boils at 92. Methyl Urea Chloride, CO^^rr r-^r , melts about 90 and boils at 93-94. These compounds boil apparently without decomposition, yet they suffer dissocia- tion into hydrochloric acid and isocyanic acid esters, which reunite on cooling: CO . NR + HC1 = Dialkyl Urea Chlorides : Dimethyl Urea Chloride, CO< t boils at 167 C. Diethyl Urea Chloride, CO melting at 132-133, was discovered by v. Rouelle in urine in 1773, and was first synthesized from isocya- nate of ammonium by Wohler in 1828 (Pogg, A. (1825) 3, 177; (1828) 12, 253). This was a brilliant discovery, which showed that organic as well as inorganic compounds could be built up artificially from their elements (p. 17). It occurs in various animal fluids, chiefly in the urine of mammals, and can be separated as nitrate from concentrated urine on the addition of nitric acid. It is present in small quantities in the urine of birds and reptiles. A full-grown man voids upon an average about 30 grams of urea daily. The formation of this substance is due to the decomposition of albuminoid substances. It may be prepared artificially: (i) by evaporating the aqueous solu- CARBAMIDE. 397 tion of ammonium isocyanate, when an atomic transposition occurs (Wohler): CO : N . NH 4 yields Mixed aqueous solutions of potassium cyanate and ammonium sulphate (in equiva lent quantities) are evaporated ; on cooling, potassium sulphate crystallizes out and is filtered off, the filtrate being evaporated to dryness, and the urea extracted by means of hot alcohol. This is also a reversible process. On heating y^n urea solution for some time to 100, four to five per cent, of the urea will be changed to ammonium cyanate (B. 29, R. 829). It is also formed by the methods in general use in the preparation of acid amides : (2) by the action of ammonia (#) upon carbamic esters or urethanes, () upon alkylic carbonic esters, (V) upon fused phenyl carbonate (B. 17, 1286), and (//) upon chlorcarbonic esters. The bodies mentioned under b, c and d first change to carbamic esters : NH 2 . CO 2 C 2 H 5 -f NH 3 == NH 2 CONH 2 -f C 2 H 5 OH CO(OC 2 H 5 ) 2 -j- 2NH 3 = NH 2 CONH 2 -f- 2C 2 H 5 OH C6(OC 6 H 5 ) 2 -|- 2NH 3 = NH a CONH, + 2C 6 H 5 OH C1(CO 2 C 2 H.) -f 3NH, = NH 2 CONH 2 + C 2 H 5 OH + NH 4 C1. (3) By the action of ammonia upon phosgene and urea chloride : COC1 2 -f 4NH 3 = CO(NH 2 ) 2 + 2NH 4 C1 C1CONH 2 -f 3 NH 3 = CO(NH 2 ) 2 + NH 4 C1. (4) By heating ammonium carbamate or thiocarbamate to 130- 140. The two following methods of formation show the genetic relation of urea with thiourea, cyanamide and guanidine : (5) Potassium permanganate oxidizes thiourea to urea. (6) Small quantities of acids convert cyanamide into urea : CN . NH 2 -f H 2 O = OO K - Methyl Acetyl Urea Methyl Urea. Ureas of this class are perfectly analogous to ordinary urea so far as properties and reactions are concerned. They generally form salts with one equivalent of acid. They are crystalline salts, with the exception of those containing four alkyl groups. On heating those with one alkyl group, cyanic acid (or cyanuric acid) and an amine are produced. The higher alkylized members can be distilled without decomposition. Boiling alkalies convert them all into CO 2 and amines : NH ' CH3 + H 2 = C 2 + NH 3 + NH 2 ' CH 3' (4) By desulphurizing the alkylic thio-ureas with an alcoholic silver nitrate solu- tion (B. 28, R. 915). Methyl Urea, CO^^Tj ' 3 , results on heating methyl aceto-urea (from aceta- mide by the action of bromine and caustic potash) with potassium hydroxide. It melts at 102. Ethyl Urea, CO< ' melts at 9 2 - a Diethyl Urea, CO< ' 25 , melts at 112 and boils at 263. -Diethyl Urea, CO< 2 ^ , melts at 70. Triethyl Urea, CO<:Kfr'w 2 ^ 5 > melts at 63 and boils at 223. i>H^ 2 n 5 ) 2 Tetraethyl Urea, CO5H K boils at 210-215, arj d ha s an odor resem- m H Ji bhng that of peppermint. Allyl Urea, CO<^[{ ' C;jH5 , melts at 85, and is converted by hydrogen fT-T r^TT-- f~\ bromide into prbpylene-^-urea (p. 404), 3 ' ( . >C : NH (B. 22, 2990). CH 2 NH Diallyl Urea, c OCH 2 , consists of white, granular crystals (B. 29, 275i)- Ethidene Urea, CO<^>CH. CH 3 , melts at 154. Ethylene Urea, CO< NHCH 2 , isomeric with ethidene urea, is produced on beating ethyl carbonate to 180, together with ethylene-diamine. Needles, melting at 131. Dinitro-ethylene Urea, CO< Trimethylene Urea, CO<^ * 2 >CH 2 , melts at 260 (A. 232, 224). Ethylene Diurea, -^JT >C 2 H 4 , is produced upon heating ethylene dia- CO CO(?), is obtained from glyoxal and urea, as well as by the reduction of allantoin (B. 19, 2477). Nitric acid converts it into Dinitroglycoluril, Acetylene-dinitro-diurei'ne, NH . CH . N(NO 2 ) CO<^ i ^>CO, decomposes at 217, and when boiled with water JN .H. . \^ il . JN ( IN Oo J NH.CH.OH passes into glycolurelne, CO< i^ , isomeric with hydantoic acid. Con- NH . CH . OH suit B. 26, R. 291, for the action of urea upon acetyl acetone. DERIVATIVES OF UREA WITH ACID RADICALS, OR UREIDES. The urea derivatives of the monobasic acids are obtained in the action of acid chlorides or acid anhydrides upon urea. By this pro- cedure, however, it is possible to introduce but one radical. The compounds are solids; they decompose when heat is applied to them, and do not form salts with acids. Alkalies cause them to separate into their components. Formyl Urea, NH 2 . CO . NH . CHO, melts at 167 (B. 29, 2046). NH C 1 H O Acetyl Urea, COCO, CO NH melting at 165, can be prepared from cyanacetyl cyanide, by transposing it to diethylcyanacetyl cyanide, and then letting bromine and caustic potash act upon the latter. The non-tangible intermediate product, (C 2 H 5 ) 2 C<^-^ 2 , rearranges itself into a-diethyl-hydantom (B. 29, R. 517). fi-LactylUrea, i : i , melting at 275 (B. 29, R. 509), is analogously CH 2 .NH.CO CIL . CO . NH 2 obtained from the unstable intermediate product, i , resulting from the ^x-ITlo -^ ^V-J action of bromine and caustic potash upon succinamide. The ure'ides of glyoxylic acid, acetoacetic acid, oxalic acid, malonic acid, tartronic acid and mesoxalic acid will receive attention under the uric acid derivatives. Di- and Tricarboxylamide Derivatives. Ureldes of Carbonic Acid. Free dicarbamidic or imidodicarbonic acid cannot exist. Some of its derivatives are rather remarkable. They sustain the same relation to carbamic acid that diglycola- midic acid bears to glycocoll. A derivative of tricarbamidic acid is known : 1M1DODICARBON1C ESTER. 403 NH CH,.00,H N'CH -Urea. Ethylene-pseudo-Urea, i ^>C : NH, or CH 2 NH CH 2 Ox. I, ^C.NH 2 , is produced by the action of brom-ethylamine hydrobromide v- Aio JN/'^ upon potassium cyanate. It is a basic oil, which solidifies with difficulty. Propylene-i/>-Urea, C 3 H 6 : CON 2 H 2 , results from HBr-propylamineand potassium cyanate, as well as from allyl urea, by a molecular rearrangement induced by hydro- bromic acid (B. 22, 2991). Diamide- or Hydrazine, and Di-imide Derivatives of Carbonic Acid. Hydrazine Carbonic Ester, NH 2 . NH . CO 2 . C 2 H 5 , is formed by reducing nitro- urethane with zinc and acetic acid. Its benzol derivative, C 6 H 5 . CH : N . NH .- CO 2 . C 2 H 3 , melts at 135 (A. 288, 293). SEMICARBAZIDE. AZOD1CARBONIC ACID. 405 Semicarbazide, Carbamic Ilydrazide, NII a . CO . NH . NH 2 , melting at 96, is formed (i) by heating urea and hydrazine hydrate to 100 (J. pr. Ch. [2], 52, 465) ; (2) from hydrazine sulphate and potassium cyanide ; (3) from amido-guamdine (B. 27, 31, 56) ; (4) from nitro-urea (A. 288,311). With benzaldehyde it yields benzal- semicarbazide, NH 2 . CO . NHN = CH . C a H 5 , melting at 214. Acetone Semicar- bazone, NH 2 . CO. NH . N :C(CH 3 ) 2 , melting at 187, passes into bisdimethylazi- methylene (p. 220) (B. 29, 61 1). Acetoacetic Ester Carbazone, NH, . CO . NH . N : C(CH 3 ) . CH 2 . CO 2 C 2 H 5 , melt- ing at 129 (A. 283, 18), readily passes into a lactazam. Semicarbazide condenses with benzil to l.2-diphenyl oxytriazine. Semicarbazide is a reagent for aldehydes and ketones. Carbohydrazide, NH 2 . NH . CO . NH . NH 2 , melting at 152-153, is obtained from carbonic ester and hydrazine hydrate on heating to IOO (J. pr. Ch. [2] 52, 469). Dibenzal Carbohydrazide, CO(NH . N = CH . C 6 H 5 ) 2 , melts at 198. Hydrazo-dicarbonic Ester, Hydrazi-carbonic Ester, C 2 H 5 O . CO . NH . NH . CO .- O . C 2 H 5 , melting at 130, boils with decomposition about 250, and is prepared from hydrazine and Cl . CO 2 C 2 H 5 (B. 27, 773; J. pr. Ch. [2] 52, 476). Hydrazo-dicarbonamide, Hydrazo-formamide, NH 2 . CONH . NH . CONH 2 , melts with decomposition at 244-245. It is obtained from potassium cyanate 'and salts of diamide or hydrazine : NH 2 . NH 2 . It also results upon heating semicarba- zide (B. 27, 57), and from Azodicarbonamide, NH 2 . CON = N . CONH 2 , by reduction. It yields the latter upon oxidation (A. 271, 127; B. 26, 405). Cyclic Hydrazine Derivatives of Urea. Urazole, Hydrazo-dicarbonimide, NH . CO I T >NH, melting at 244, forms on heating hydrazo-dicarbonamide to 200 NH . CO (A. 283. 16), or from urea and hydrazine sulphate heated to 120 (B. 27, 409). See also triazole. It is a strong, monobasic acid. Methylene Carbohydrazide, CO CO ' meltin S at 2 7 from hydrazine carbonic ester and hydrazine hydrate at IOO (B. 27, 2684; T. pr. Ch. [2], 52, 482). Azodicarbonic Acid, Azoformic Add, CO 2 H . N = N . CO 2 H. Its potassium salt explodes when heated above 100. It consists of small yellow needles. It is formed when azodicarbonamide is boiled with concentrated caustic potash. It readily decomposes in aqueous solution, giving off CO 2 , potassium carbonate, diamide and nitrogen. The isolation of the unknown di-imide NH = NH, present in it, has not yet proved successful. The diethyl ester, boiling at 106 (13 mm.) is an orange- yellow-colored oil, and is formed when nitric acid acts upon the hydrazoester. Azodicarbonaniide, Azoformamide, NH 2 CON = NCONH 2 , is an orange-red- colored powder. It is produced (i) on oxidizing hydrazodicarbonamide with chromic acid ; (2) by boiling the aqueous solution of the nitrate of azodicarbonaniidme, NH NH Potassium Azimethane Disulphonate , \ ' . 2H 2 O, is formed on boiling N : C(SO 3 K) 2 N potassium diazomethane-disulphonate, \\ >C(SO 3 K) 2 , in xylene solution. Orange- yellow-colored needles, which result when a solution of potassium nitrite acts upon primary potassium amino-methane disulphonate, NH 2 . CH(SO 3 K) 2 the addition product of prussic acid and monopotassium sulphite (B. 29, 2161). Hydroxylamine Derivatives of Carbonic Acid. Oxyurethane, HO . NH . - ORGANIC CHEMISTRY. O C TT CO 2 . C 2 H 5 , or HON : C^QJ-J 2 5 , is a colorless liquid. It is produced when an hydroxylamine solution acts upon chlorcarbonic ester (B. 27, 1254). Hydroxyl Urea, NH 2 . CO. NH . OH, melting at 128-130, dissolves readily in water and alcohol, but with difficulty in ether. It is obtained from hydroxylamine nitrate and potassium isocyanate (A. 182, 214). SULPHUR-CONTAINING DERIVATIVES OF CARBAMIC ACID AND OF UREA. The following compounds correspond to urethane and urea : rn , 2 r<; . 2 r c^2 rc/ 2 r/ 2 C 2 H 4 , is obtained from ethylene-diam- ine and carbon disulphide (B. 5, 242). It melts at 195. Pinacolyl Sulphocarbamide, Tetramethyl-ethylene-sulphocarbamide, Carbothiace- tonine, CS[NHC(CH 3 ) 2 ] 2 , melts at 24O-243,and is formed by the action of ammonia upon carbon disulphide and acetone (B. 29, R. 669). Derivatives of Pseudosulphocarbamide. In the preceding derivatives (immaterial whether they are derived from the sym. or unsym. Sulphocarbamide formula) the alkyl groups were in all cases joined to nitrogen, whereas the compounds about to be described must be considered as derivatives of pseudosulphocarbamide. The alkylic psendosidphocarbamides result upon the addition of alkyl iodides to the thioureas. The alkyl groups contained in them are united with sulphur because, when they are acted upon with ammonia, they are changed to guanidines and mer- captans (B. n, 492 ; 23, 2195). 35 410 ORGANIC CHEMISTRY. Alkylen Derivatives of Pseudosulphourea. c (~*FT Ethylene-pseudothiourea, NH . C< i * or, more probably, NH . CH 2 i 2 , is obtained from HBr-ethyleneamine and potassium thiocyanate. - V^IJ It is a base with strong basic properties. Its salts crystallize well. It melts at 85 (B. 22, 1141, 2984; 24, 260). Propylene-pseudothiourea, C 3 H 6 : CSN 2 H 2 , from brompropylamine and potas- sium thiocyanate, is perfectly similar. It also results from allyl thiourea by action of hydrobromic acid : CH 2 = CH ^LHBr_^ CHs CHBr ^__+ CH 3 CH-S X CH 2 NH . CSNH 2 H H CH 2 N^ Acetyl Pseudosulphocarbamide, HN = CNH, melts at about 245 with decomposition, and is NH . CS GUANIDINE AND ITS DERIVATIVES. 411 formed on heating hydrazodicarbonthiamide with hydrochloric acid. The hydro- chloride of imidothiourazole, i ^>NH, is produced at the same time (B. 28, 949). GUANIDINE AND ITS DERIVATIVES. Guanidine is, upon the one hand, very closely related to orthocar- bonic ester, urea and sulphocarbamide, and, upon the other, to cyana- mide (p. 426). The carbonic acid derivatives just mentioned are united by a series of reactions. Guanidine belongs to the amidines, and may be regarded as the amidine of amidocarbonic acid : NH r /NH 2 r /NH 2 1 H 2 ' %0 ' H 2 ' S.S Urea Sulphocarbamide Guanidine. The pseudo-forms of urea and thiourea ' HO C XNH ' HS U 'Ss,NH b ' (Pseudourea) (Pseudosulphocarbamide) . known in the form of various derivatives, are the amidines of carbonic and thiocarbonic acids. Guanidine, HN : C<^ 2 , was first obtained (A. Strecker, 1861) by the oxidation of guanine (a substance closely related to uric acid, and found in guano) with hydrochloric acid and potassium chlorate. It is found in certain seeds and in beet-juice (B. 29, 2651). It is also important as the substance from which creatine is derived. It is formed synthetically (i) by heating cyanogen iodide and NH 3 , and from cyanamide (p. 426) and ammonium chloride in alcoholic solu- tion at 100: /NH 2 . HC1 CN . NH 2 This is analogous to the formation of formamidine from HCN. (2) It is also produced by heating chloropicrin or (3) esters of ortho carbonic acid, with aqueous ammonia, to 150 : CC1 3 (N0 2 ) + 3 NH, = NH 2 C 2 + 3 HC1 + NO 2 H C(0. C a H 6 ) 4 + 3 NH 3 = NH 2 C<^ 2 + 4 C 2 H 5 OH. (4) It is most readily prepared from the sulphocyanate, which is made by prolonged heating of ammonium sulphocyanate to 180-190, and the further transposition of the thio-urea that forms at first (B. 7, 92) : 2 H 2 N >CS = H 2 N >C ' NH ' CNSH + H ' S ' 412 ORGANIC CHEMISTRY. The crystals of guanidine are very soluble in water and alcohol, and deliquesce on exposure. Baryta water changes it to urea. Salts. It is a strong base, absorbing CO 2 from the air and yielding crystalline salts with I equivalent of the acids. The nitrate, CN 3 H 5 . HNO 3 , consists of large scales, which are sparingly soluble in water. The HCl-salt, CN 3 H 5 . HC1, yields a platinum double salt, crystallizing in yellow needles. The carbonate, (CN 3 H 5 ) 2 . - H 2 CO 3 , consists of quadratic prisms, and reacts alkaline. The sulphocyanate, CN 3 - H 5 . HSCN, crystallizes in large leaflets, that melt at Il8. The alkyl guanidines result (l) on heating cyanamide with the HCl-salts of the primary amines e g., Methyl Guanidine; (2) by boiling sym. dialkylic thio-ureas (p. 408) with mercuric oxide and ethylamine in alcoholic solution (B. 2, 601) : Tri- ethyl Guanidine. Vice versa, the alkylic guanidines, when heated with CS 2 , have their imid-group replaced by sulphur, with formation of thio-ureas. Guanidine also forms salts with the fatty acids. When these are heated to 220- 230, water and ammonia break off", ancl the guanamines result. These are pecu- liar heterocyclic bases (Nencki, B. 9, 228). They are produced by the union of I molecule of acid and 2 molecules of guanidine. Formoguanamine is also produced when chloroform and caustic potash act upon N = C X biguanide (p. 419) (B. 25, 535). These bases contain the ring C <^ ">N, ^N C^ assumed to be present in the cyanuric compounds. N = C(NH 2 ) For moguanaii line, HC\ /N, melts with decomposition at high tem- N = C(NH 2 ) peratures. Acetgttanannne, CHoC^ /N, melting at 265, when heated ^N = C(NH 2 )^ with concentrated H 2 SO 4 to 150 passes into acetguanamide ; see acetylurethane. Guaneides of the Oxyacids. The guanidine derivatives corre- sponding to the ureides of glycollic acid, hydantoi'c acid, and hydan- toin are known. Creatine and creatinine, important from a physio- logical standpoint, belong to this class. Glycocyamine, guanidoacetic acid, NH = C< jjCH CQ H' is obtained b y the direct union of glycocoll with cyanamide : p-vr -VTT-T _i_ pir ^-NHg p NH L^IN . IN rl 2 -f- v^-Ti2 \(~"O TT V-^=l> A A Cyanamide Glycocoll Glycocyamine. On mixing the aqueous solutions it separates after a time in granular crystals. It dissolves with difficulty in cold water and rather readily in hot water ; while it is insoluble in alcohol and ether. It forms crystalline compounds with acids and bases. /3-Guanidopropionic Acid, Alacreatine, CN 3 H 4 . CH 2 . CH 2 . CO 2 H, consists of crystals which decompose at 205. Isomeric a-guanidopropionic acid melts at 180. Glycocyamidine, glycolyl guanidine, NH = C< I , bears the same relation to glycocyamine as hydantoin to hydantoi'c acid : GUANIDINE AND ITS DERIVATIVES. 413 NIL, NHCO Mi., NHCO C + = NH : C< " - CH, - co 2 H. Creatine crystallizes with one molecule of water in glistening prisms. Heated to 100, they sustain a loss of water. It reacts neutral, has a faintly bitter taste, and dissolves rather readily in boiling water; it dissolves with difficulty in alcohol, and yields crystalline salts with one equivalent of acid. (i) When digested with acids, creatine loses water and becomes creatinine (see above), and (2) with baryta water it falls into urea and sarcosine : NH 2 NH 2 NH(CH 3 ) < N(CH 3 ) CH 2 C0 2 H + H2 < NH 2 + CH 2 . CO 2 H. Ammonia is liberated at the same time, and methyl hydantoin is formed. (3) When its aqueous solution is heated with mercuric oxide, creatine becomes oxalic acid and methyl guanidine. (4) With acetic anhydride it yields diacetyl creatine, NH CO CH NH . C melting at 165 (A. 284, 51). IS ^v^rl 3 j . l^ri2 v-'Vj . U . L^iJv-rl^ Creatinine, methyl glycocyamidine, NH = C< i , occurs N(CH 3 )CH 2 constantly in urine (about 0.25 per cent.), and is readily obtained from creatine by evaporating its aqueous solution, especially when acids are present. It crystallizes in rhombic prisms, and is much more soluble than creatine, in water and alcohol. It is a strong base, which can expel ammonia from ammonium salts and yields well crystallized salts with acids. Its compound with zinc chloride, (C 4 H 7 N 3 O) 2 . ZnCl 2 , is particularly characteristic. Zinc chloride pre- cipitates it from creatinine solutions as a crystalline powder, dissolving with difficulty in water. (i) Bases cause creatinine to absorb water and become creatine again. (2) Boiled with baryta water it decomposes into methyl hydantoin and ammonia : " NH : C< I + H 2 = OX I + NH,. ^ T T 414 ORGANIC CHEMISTRY. (3) When boiled with mercuric oxide it breaks up like creatine into methyl -guanidine and oxalic acid. When creatinine is heated with alcoholic ethyl iodide, the ammonium iodide of ethyl creatinine, C 4 H 7 (C 2 H 5 )N 3 O . I, is produced. Silver oxide converts this into the ammonium base, C 4 H 7 (C 2 H 5 )N 3 O . OH. Guanei'des of Carbonic Acid. Guanoline, guanyl urea, biguanide, and proba- bly dicyandiamide, corresponding to allophanic ester (p. 403), biuret (p. 403), and cyanurea (p. 403), are derivatives of the guaneide of carbonic acid. This is not known, and probably cannot exist : co NH 2 CO^ NH ' CO n 2 ^ ^ s f rme d (l) on heat- ing guanidine hydrochloride to 180-185; (2) when cyanguanidine is heated with ammonium chloride. It is a strongly alkaline base, forming a copper derivative with characteristic red color. Chloroform and caustic alkali convert it m\.o fonnoguanamine (p. 412). Dicyandiamide, Param, Cyanguanidine, NH : CC : NH, was ascribed to this compound. Its behavior with piperidine, with which it combines to form a biguanide derivative, indicates the cyanamidine formula (B. 24, 899 ; 25, 5 2 5)- See guanazole, p. 415. NITRO-GUANIDINE AND ITS TRANSPOSITION PRODUCTS. Nitroguanidine is the starting-out material for the preparation of a series of remark- able guanidine and urea derivatives (Thiele, A. 270, I; 273, 133; B. 26, 2598, 2645). Nitroguanidine, NH : C< NH 2 , melting at 240, results on treating guanidine with a mixture of nitric and sulphuric acids. It dissolves with difficulty in cold NITRO-GUANIDINE AND ITS TRANSPOSITION PRODUCTS. 415 water, more readily in hot water, and very copiously in alkalies, because of its feeble acid character. Xitroso-gnanidine, NH : C<\,TT * (?)> * s produced by reducing nitroguanidine with zinc dust and sulphuric acid. It consists of yellow needles, exploding at 160- 165. Amido-guanidine, NH:C<^ir 2 , results when nitro- and nitroso-guanidine are reduced with zinc dust and acetic acid. Amido-guanidine decomposes readily when in a pure condition, and when boiled with acids it breaks down, with the tem- porary production of semicarbazide (p. 405), into carbonic acid, ammonia, and hydra- zine, which can therefore be conveniently prepared in this manner : r NH . NH 2 H 2 / NHNH 2 \ H 2 O NH 2 NH 2 H ' C ( CO C0 ' + NH*. Amido-guanidine forms well-crystallized compounds with dextrose, galactose, and lactic acid (B. 28, 2613). /NH N Amidomethyl-triazole, NH 2 C<^ II (?) } melting at 148, is produced \ JN \^ . \-s 1"1 g when acetylamido-guanidine nitrate is treated with soda. NH XH Gnanazole, NH : C<[,. i , melting at 206, results when dicyandiamide (see above) is heated with hydrazine hydrochloride in alcoholic solution to 100 (B. 27, R. 583)- NH NH 2 Azodicarbondiamidine, \C N = N C\ , is obtained as nitrate when NH * ^NH amido-guanidine nitrate is oxidized with KMnO 4 . The azonitrate forms a yellow, sparingly soluble, crystalline powder, exploding at 180-184. It passes into azodi- carbonamide (p. 405) when boiled with water. NH NH 2 Hydrazodicarbonamidine, ;C NH NH - C\ , results as nitrate when NH * ^NH azodicarbonamidine nitrate is reduced with H 2 S. - Diazoguanidine Dinitrate, NH : C con . sists of colorless crystals, readily soluble in water and alcohol, but insoluble in ether. It is obtained when potassium nitrite acts on the nitric acid solution of amidoguani- dine nitrate. Caustic soda converts it into cyanamide and hydronitric acid, and by acids in addition in part into amidotetrazotic acid, melting at 203. This acid, with its decomposition products, will be mentioned after tetrazole : /N _N0 3 H /NH-N=N-N0 3 _N0 3 H /N N CNNH 2 +HNC N N CCO, is formed (A. 249, 27). These heterocyclic bodies, derived from the products of the interaction of ammo- nium sulphocyanide with a-chlorketones and a-chlor-fatty acids, belong to the class of thiazoles. Mustard Oils, Esters of Isothiocyanic Acid, Alkyl Thiocarbimides. The esters of isothiocyanic acid, CS : NH, not known in a free con- dition, are termed mustard oils, from their most important representa- tive. They may also be considered as sulphocarbimide derivatives. They are produced (i) by the rearrangement of the isomeric alkyl sulphocyanides on the application of heat (p. 422) : CNS.C 3 IL ^^ 'OF T UNIVE 424 ORGANIC CHEMISTRY. (2) By mixing carbon disulphide with primary amines in alcoholic or, better, ethereal solution. By evaporation we get amine salts of alkyl carbamic acids (B. 23, 282). On adding silver nitrate, mercuric chloride (B. 29, R. 651) or ferric chloride (B. 8, 108) to the aqueous solution of these salts, formed with primary amines, and then heating to boiling, the metallic compounds first precipitated decompose into metallic sulphides, hydrogen sulphide and mustard oils, which distil over with steam. S . NH 3 (C 2 H 5 ) Hofmann's mustard oil test for the detection of primary amines (p. 1 66) is based on this behavior (B. i, 170). Iodine, too, forms mustard oils from the amine salts of the dithiocarbamic acids, but the yield is small. (3) By distilling the dialkylic thio-ureas (see these) with phosphorus pentoxide (B. 15, 985), and (4) by heating the isocyanic esters with P 2 S 5 (B. 18, R. 72). Properties. The mustard oils are liquids, almost insoluble in water, and possess a very penetrating odor, which provokes tears. They boil at lower temperatures than the isomeric thiocyanic esters. Transformations. (i) When heated with hydrochloric acid to 100, or with H 2 O to 200, they break up into amines, hydrogen sulphide, and carbon dioxide : CS : N . C 2 H 5 + 2H 2 = C0 2 + SH 2 + NH 2 . C 2 H 5 . (2) On heating with a little dilute sulphuric acid, carbon oxysulphide, COS, is formed, together with the amine. (3) When heated with car- boxylic acids they yield monoacidyl acid amides and COS ; and (4) with carbonic anhydrides, diacidyl amides and COS (B. 26, 2648). (5) Nascent hydrogen (zinc and hydrochloric acid) converts them into thio-formaldehyde and primary amines: CS: N . C 2 H 5 -f 2H 2 = CSH 2 + NH 2 . C 2 H 5 . (6) When the mustard oils are heated with absolute alcohol to 100, or with alcoholic potash, they pass into sulph-urethanes. (7) They unite with ammonia and amines, yielding alkylic thio-ureas (see these). (8) Upon boiling their alcoholic solution with HgO or HgCl 2 , a substitution of oxygen for sulphur occurs, with formation of esters of isocyanic acid. These immediately yield the dialkylic ureas with water (see p. 398). (9) Consult A. 285, 154, for the action of the halogens upon the mustard oils. Methyl Mustard Oil, CS : N . CH 3 , methyl isosulphocyanic ester, methyl sulpho- carbimide, melts at 34 and boils at 119. Ethyl Mustard Oil boils at 133, and has a specific gravity 1.019 at - Propyl Mustard Oil boils at 153. Isopropyl Mustard Oil boils at 137. n-Butyl Mustard Oil boils at 167. Isobutyl Mustard Oil boils at 162. ALLYL MUSTARD OIL. 425 Tertiary Butyl Mustard Oil boils at 142. n-Hexyl Mustard Oil boils at 212. Heptyl Mustard Oil boils at 238 (B. 29, R. 651). Secondary Octyl Mustard Oil boils at 232. The most important of the mustard oils is the common or Allyl Mustard Oil, CS : N. C 3 H 5 , Ally I Isosulphocyanic Ester. This is the principal constituent of ordinary mustard oil, which is ob- tained by distilling powdered black mustard seeds (from Sinapis nigra), or radish oil from Cochlearia armoracia, with water. Mustard seeds contain potassium myronate (see Glucosides), which in the presence of water, under the influence of a ferment, myrosin (also present in the seed), breaks up into grape sugar, primary potassium sulphate, and mustard oil. The reaction occurs even at o, and there is a small amount of allyl sulphocyanate produced at the same time : q o H 18 KNO 10 S, = C 6 H 12 O 6 + SO 4 KH -f CS . N . C 3 H 5 . Mustard oil is artificially prepared by distilling allyl iodide or bro- mide with alcoholic potassium or silver thiocyanate (Gerlich, A. 178, 80): CN . SK -f C 8 H 5 I = CS . N . C 3 H 5 -f KI ; a molecular rearrangement occurs here (p. 52). Pure allyl mustard oil is a liquid not readily dissolved by water, and boiling at 150.7; its specific gravity equals 1.017 at 10. It has a pungent odor and causes blisters upon the skin. When heated with water or hydrochloric acid the following reaction ensues : CS : N . C 3 H 5 -f 2H 2 O = CO 2 -f SH 2 -f NH 2 . C 3 H 5 . It unites with aqueous ammonia to form allyl thio-urea. When heated with water and lead oxide it yields diallyl urea. Acidyl thiocarbimides are produced by the action of fatty-acid chlorides, dissolved in benzene, upon lead sulphocyanide. Valeryl thiocarbimide, C 4 H 9 CO . N : CS (B. 29, K. 85), and Carboxethyl thiocarbimide', JA) . CO . N : CS, boiling at 66 (21 mm. ) (B. 29, R. 514), were obtained in this manner. T/iio- or sulphocyanuric Acid, C 3 N 3 (SH) 3 , corresponds to cyan uric acid. Isothio- cyanuric acid is as little known as i-ocyanuric acid. Thiocyanuric acid results from cyanuric chloride (p. 421) and potassium sulphydrate. It consists of small yellow needles, which decompose but do not melt above 200. Its esters result when cyanuric chloride and sodium mercaptides interact, and by the polymerization of the thiocyanic esters, CN . SR, when heated to 180 with a little HC1. More HC1 causes them to split up into cyanuric acid and mercaptans. Methyl Ester, C 3 N 3 (S . CH 3 ) 3 , melts at 188, and with ammonia yields mela- mine (p. 427). Isothiocyanuric Esters, C 3 S 5 (NR / ) 3 , appear to have been formed by the polymeriza- tion of mustard oils with potassium acetate (B. 25, 876). 36 426 ORGANIC CHEMISTRY. CYANAMIDE AND THE AMIDES OF CYANURIC ACID. Cyanamide, CN. NH 2 , the nitrile of carbamic acid, absorbs water and passes into urea, the amide of carbamic acid. It manifests certain reactions, which would rather point to its being NH = C = NH, car- bodiimide. A definite decision as to which of the two formula possi- bilities is the correct one cannot be given. It is formed (i) by the action of chlor- or brom-cyanogen upon an ethereal or aqueous solu- tion of ammonia (Bineau, 1838; Cloe'z and Cannizzaro, 1851) : CNC1 + 2NH 3 = CN . NH 2 -f NH 4 C1 ; and also (2) by the desulphurizing of thiourea by means of mercuric chloride or lead peroxide (mercuric oxide is preferable) (B. 18, 461) : CS CH ' + H ' a Glutaric Acid Glutaric Anhydride. When the carbon atoms, carrying the carboxyl groups, are separated by two carbon atoms from each other, e. g., adipic acid, CO 2 H . - CH 2 . CH 2 .CH 2 . CH 2 . CO. 2 H, they do not influence one another on the application of heat. Therefore, the numerous paraffin dicarboxylic acids are arranged in different groups, and after oxalic acid the malonic acid group, the succinic acid group, and the glutaric acid group will be discussed. Then will follow adipic acid, suberic acid, sebacic acid and others not belonging to any one of the three acid groups mentioned above. Formation. The most important general methods are (i) Oxidation of (a) diprimary glycols, () primary oxyaldehydes, (c) dialdehydes, (a) primary oxyacids, and (e) aldehyde acids (p. 363) : CO 2 H Glycollic Acid " Glyoxal Glyoxylrc Acid Oxalic Acid. The dibasic acids are also formed when the fatty acids and the acids of the oleic acid series, as well as the fats, are oxidized by nitric acid. Certain hydrocarbons, C n H 2n , have also been converted into dibasic acids by the action of potassium permanganate. (2) By the reduction of unsaturated dicarboxylic acids : CH . CO 2 H CH 2 . CO 2 H CH.C0. 2 H " ~CH 2 .C0 2 H Fumaric Acid Ethylene Succinic Acid. 43 ORGANIC CHEMISTRY. (3) When oxydicarboxylic acids and halogen dicarboxylic acids are reduced. Nucleus-synthetic Methods of Formation. These are very numerous with the dicarboxylic acids. (4) When silver in powder form (B. 2, 720) acts upon mono-iodo(or bromo-) fatty acids : /3-Iodopropionic Acid Adipic Acid. Consult trialkylic glutaric acids for the abnormal course of this reaction when a-bromisobutyric acid is used. (50) Conversion of monohalogen substituted fatty acids into cyan- derivatives, and boiling the latter with alkalies or acids (pp. 240 and 266): CO . OH Cyanacetic Acid Malonic Acid. Conversion of the halogen addition products of the alkylens, C n H 2n , into cyanides and the saponification of the latter : I +4H 2 0= | CH 2 .CN CH 2 CH 2 .C0 2 H C0 2 H +2NH S . Only the halogen products having their halogen atoms attached to two different carbon atoms can be converted into dicyanides. (6) In the synthesis of the mono- and dialkylic malonic acids it is of the first importance to replace the hydrogen atoms of the CH 2 group of the malonic acid in its esters by alkyl groups, just as was done in the case of acetoacetic ester (p. 373). This reaction will be more fully developed in the malonic acid group (p. 439). (7) By the electrolysis of concentrated solutions of alkyl ether potassium salts of the dicarboxylic acids (see electrolysis of the mono- carboxylic acids (pp. 76, 83, 243) : CH 2 . C0 2 . C 2 H 5 CH 2 . C0 2 . C 2 H 5 2 I + 2H 2 = \ + 2 C0 2 + 2KOH + 2 H. C0 2 K CH 2 . C0 2 . C 2 H 5 Potassium Ethyl Succinic Dietliyl Malonate Ester. (8) A very general method for the synthesis of dibasic acids is founded upon the transposition of acetoacetic esters. Acid residues are introduced into the latter and the products decomposed by con- centrated alkali solutions (p. 375). Thus, from acetomalonic ester we get malonic acid : CH 3 . CO . CH anc ^ glutarimide, V_-fl 2 ^-Aj 2 ' >NH. They have been previously mentioned. Q OXALIC ACID AND ITS DERIVATIVES. (1) Oxalic Acid, [Ethan-diacid], C 2 O 4 H a (Acidum oxalicutri), occurs in many plants, chiefly as potassium salt in the different varieties of Oxalis and Rumex. The calcium salt is often found crystallized in plant cells; it constitutes the chief ingredient of certain calculi. The acid may be prepared artificially (i) by oxidizing many carbon com- pounds, such as sugar, starch and others, with nitric acid. Frequent mention has been made of its formation in the oxidation of glycol, glyoxal, glycollic acid and glyoxalic acid (pp. 295, 429). (2) From cellulose : by fusing sawdust with caustic potash in iron pans at 200-220. The fusion is extracted with water, precipitated as cal- cium oxalate, and this then decomposed by sulphuric acid (technical method). (3) It is formed synthetically by (a) rapidly heating sodium formate above 440 (B. 15, 4507) : CHO . ONa __CO , CHO.ONa-io.ONa 4 " by (<) oxidizing formic acid with nitric acid (B. 17, 9). (4) By conducting carbon dioxide over metallic sodium heated to 350-360 (A. 146, 140): 2 CO 2 + Na 2 = C 2 O 4 Na 2 . (5) Upon treating their nitrites, cyancarbonic ester and dicyanogen, with hydrochloric acid or water: CN CO 2 H CN CO 2 C 2 H 5 " ^ CO 2 H "* ~CN ' OXALIC ACID. 433 History. In the very beginning of the seventeenth century salt of sorrel was known, and was considered to be a variety of argol.* Wiegleb (1778) recognized the peculiarity of the acid contained in it. Scheele had obtained the free oxalic acid as early as 1776 upon oxidizing sugar with nitric acid, and showed in 1784 that it was identical with the acid of the salt of sorrel. Gay-Lussac (1829) discovered that oxalic acid was formed by fusing cellulose, sawdust, sugar, etc., with caustic potash. This process was introduced into practical manufacture in 1856 by Dale. Constitution. Free oxalic acid crystallizes with two molecules of water of crystallization. The crystallized acid is probably ortho-oxalic acid, C(OH) 3 . C(OH) 3 (p. 224). Ortho-esters of the acid C 2 (OR') 6 are not known, but esters do exist, which are derived from the non- isolated half -ortho-oxalic acid, C(OH) 3 . CO 2 H. Properties and Transformations. Oxalic acid crystallizes in mono- clinic prisms, which effloresce at 20 in dry air. Large quantities of the acid, introduced into the system, are poisonous. It is soluble in 9 parts of water of medium temperature, and quite easily in alcohol. The hydrated acid melts at 101 if rapidly heated, and the anhydrous at 189 (B. 21, 1901). Anhydrous oxalic acid crystallizes from concen- trated sulphuric and nitric acid (B. 27, R. 80), and will serve as a con- densation agent for the splitting off of water (B. 17, 1078). When carefully heated to 150 the anhydrous acid sublimes undecomposed. (i) Rapidly heated it decomposes into formic acid and carbon dioxide and also into CO 2 , CO and water : C 2 H 2 O, = CH 2 O 2 -f CO 2 ; C 2 H 4 O 2 = CO 2 -f CO + H 2 O. (2) An aqueous oxalic acid solution under the influence of light decomposes into CO 2 , H 2 O, and with sufficient oxygen access, H 2 O 2 (B. 27, R. 496). (3) Oxalic acid decomposes into carbonate and hydrogen by fusion with alkalies or soda-lime : C 2 O 4 K 2 + 2KOH = 2CO 3 K 2 -f H 2 . (4) Heated with concentrated sulphuric acid it yields carbon monox- ide, dioxide and water. (5) Nascent hydrogen (Zn and H 2 SO 4 ) converts it into glycollic acid. (6) Concentrated nitric acid slowly oxidizes oxalic acid to CO 2 and water. However, permanganate of potash in acid solution rapidly oxidizes it. This reaction is used in volumetric analysis. (7) PC1 5 changes oxalic acid to POC1 3 , CO 2 , CO, and 2HC1. It has also been possible to replace 2C1 by O in certain organic dichlorides upon using anhydrous oxalic acid (p. 446). SbCl 5 , however, and ox- alic acid yield the compound (COOSbCl 4 ) 2 (A. 239, 285 ; 253, 112). The oxalates, excepting those with the alkali metals, are almost insoluble in water. The neutral potassium salt, C 2 O 4 K 2 -f- H 2 O, is very soluble in water. The acid salt y C 2 O 4 HK, dissolves with more difficulty, and occurs in the juices of plants (of Oxalis and Rumex]. Potassium quadroxalate, C 2 O 4 KH . C 2 O 4 H 2 -f- 2H 2 O. Neutral Ammonium Oxalate, C 2 O 4 (NH 4 ) 2 -+- H 2 O, consists of shining, rhombic prisms, which occur in left and right-hemihedral crystals (B. 18, 1394). The calcium oxalate, C 2 O 4 Ca -}- H 2 O, is insoluble in acetic acid, and serves for the 37 434 ORGANIC CHEMISTRY. detection of calcium and of oxalic acid, both of which are determined quantita- tively in this form. The silver salt, C 2 O 4 Ag 2 , explodes when quickly heated. Oxalic Esters. The acid and neutral esters of oxalic acid are formed simultane- ously when anhydrous oxalic acid is heated with alcohols. They are separated by distillation under reduced pressure (Anschiitz, A. 254, i). f~*(~\ f~* TJT Free Ethyl Oxalic Acid, i 2 2 5 , boils undecomposed at 117 under 15 mm. CO 2 H pressure. Its sp. gr. at 20 equals 1.2175. Norm. Propyl Oxalic Acid, CO 2 . C 3 H 7 . - CO 2 H, boils at 118 (13 mm.). Preserved in sealed tubes, the alkylic oxalic acids decompose into anhydrous oxalic acid, and the neutral esters. Distilled at the ordinary temperature, they break down mainly into oxalic ester, CO 2 , CO and H 2 O, and in part to CO 2 and formic esters. Oxalic Methyl Ester, C 2 O 2 (O. CH 3 ) 2 , melts at 54 and distils at 163. Oxalic Ethyl Ester boils at 186, and is formed upon heating oxomaionic ester (B. 27, 1304). See p. 385 for its conversion into carbonic ester. Oxalic ester, under the influence of sodium ethylate, condenses with acetic ester to oxalacetic ester, CO 2 C 2 H 5 . CO . CH 2 . CO 2 . C 2 H 5 , and with acetone to acetone oxalic ester (compare chelidonic acid] . Zinc and alkyl iodides convert the oxalic ester into dialkyl oxalic COOCH 2 esters (p. 33). Ethylene Oxalic Ester, i^ i , melts at 143 and boils at 197 (9 mm.) (B. 27, 2941). Half-ortho-oxalic Acid Derivatives. Dichloroxalic Esters : When PC1 5 acts upon the neutral oxalic esters, one of the doubly-linked oxygen atoms is replaced by 2C1 atoms : CO.O.C,H CC1 2 O.C 2 H CO.O.C 2 H 5 + C ' 5 -(k>.O.C 2 H 5 4 These products are called dichloroxalic esters (B. 28, 61 Anm.). When frac- tionated under greatly reduced pressure, they can be separated from unaltered oxalic ester. Distilled at the ordinary pressure, these esters decompose into alkyl chlorides and alkylic oxalic acid chlorides (see below). Dimethyl Dichloroxalic Ester, CC1 2 (OCH 3 ) . CO 2 CH 3 , boils at 72 (12 mm.); its sp. gr. is 1.3591 (20). Diethyl Dichloroxalic Ester boils at 85 (10 mm.). Di-n- Propyl Dichloroxalic Ester boils at 107 (lomm.). Half-ortho-oxalic Esters are produced by the transposition of dichloroxalic esters with sodium alcoholates in ether : CO 2 C 2 H 5 . CC1 2 . O. C 2 H 5 + 2C 2 H 5 ONa = CO 2 C 2 H 5 . C(O . C 2 H 5 ) 3 -f 2NaCl. Tetramethyl Oxalic Ester, C(OCH 3 ) 3 . CO . OCH 3 , boils at 76 (12 mm.) ; its sp. gr. is 1.1312. Tetraethyl Oxalic Ester boils at 98 (12 mm.) (A. 254, 31). The anhydride of. oxalic acid is not known. In attempting to prepare it CO 2 and CO are produced. However, the chlorides of the alkylic oxalic acids, and probably oxalyl chloride, are known. Chlorides of Alkylic Oxalic Acid are obtained by the action of POC1 3 upon potas- sium alkylic oxalates. It is most practically prepared by boiling dichloroxalic esters under the ordinary pressure until the evolution of the alkyl chlorides ceases (A. 254. 26). They show the reactions of an acid chloride (p. 257). With benzene hydro- carbons and A1 2 C1 6 they yield phenyl glyoxylic esters and their homologues (B. 14, 1689; 29, R. 511, 546). Methyl Oxalic Chloride, COC1 . CO 2 CH 3 , boils at 1 1 8- 120 ; sp. gr. 1.3316 (20). Ethyl Oxalic Chloride, COC1 . CO 2 . C 2 H 5 , boils at 135 ; sp. gr. 1.2223. n-Propyl Oxalic Chloride boils at 153. hobutyl Oxalic Chloride boils at 164. Amy I Oxalic Chloride boils at 184. These are liquids with a penetrating odor. Oxalyl Chloride, C 2 O 2 C1 2 (?), boils at 70. It has not been obtained free from POC1 3 . It is said to be formed when two molecules of phosphorus oxychloride act upon (CO . OC 2 H 5 ) 2 (B. 25, R. no). AMIDES OF OXALIC ACID. 435 AMIDES OF OXALIC ACID. Oxalic acid yields two amides : oxamic add, corresponding to ethyl oxalic acid, and oxamide, corresponding to oxalic ester. Oximide can be included with these : COOC 2 H 5 CO. MI, COOC 2 H 5 CONH 2 CO >NH(? x COOH CO. OH COOC 2 H 5 CONH 2 CO Ethyl Oxalic Oxamic Oxalic Oxamide Oximide. Acid Acid Ester Oxamic Acid, C 2 O 2 CC1 2 NH 2 ~^CC1 = NH~ -> C = N Oxamaethane Ethyl Oxamine Ethyl Oximide Cyancarbonic Chloride Chloride Ester. Oxamine Ortho-trimethyl Ether, CONH 2 . C(O . CH 3 ) 3 , melting at 115, is formed on heating half-ortho-oxalic methyl ester with anhydrous methyl alcoholic ammonia. Methyl Oxamic Acid, CONH(CH 3 ) . CO 2 H, melts at 146. VTT PH Ethyloxamic Acid, C 2 O 2 NH (?), is obtained from oxamic acid by the aid of PC1 5 or PC1 3 O (B. 19, 3229). The molecule is probably twice as large. Oxamide, C 2 O 2 (NH 2 ) 2 , separates as a white, crystalline powder, when neutral oxalic ester is shaken with aqueous ammonia (1817, Bau- hof). It is insoluble in water and alcohol. It is also formed on heating ammonium oxalate (1830, Dumas; 1834, Liebig), and when water and a trace of aldehyde act on cyanogen, C 2 N 2 , or by the direct union of hydrocyanic acid and hydrogen peroxide (2CNH -f- H 2 O 2 = C 2 O 2 N 2 H 4 ). Oxamide is partially sublimed when heated, the ORGANIC CHEMISTRY. greater part, however, being decomposed. When heated to 200 with water, it is converted into ammonium oxalate. P 2 O 5 converts it into dicyanogen. The substituted oxamides containing alcohol radicals are produced by the action of the primary amines upon the oxalyl esters e. g. : Sym. Dimethyl Oxamide Sym. Diethyl Oxamide. Tetrainethyl Oxamide, [CON(CH 3 ) 2 ] 2 , melting at 80, is obtained from dimethyl urea chloride by the action of ammonia (B. 28, R. 234). See also Oxanilide, later. PC1 5 converts these alkylic oxamides into amide chlorides, which lose 3HC1 and pass into glyoxaline derivatives (Wallach, A. 184, 33; Japp, B. 15, 2420): thus diethyl oxamidc yields chloroxalmethylin, and diethyl oximide yields chloroxal- ethylin : CONHCH saP ci 6 CC1 2 .NH.CH 3 _ 2H C1 CC1NCH 3 _ H C1 CH N(CH 3 ) - > II 3-CH CO . NH . CH 3 CC1 2 . NHCH 3 C C1NCH 3 CC1 N=^ Dimethyl Dimethyl Dimethyl Chloroxalmethylin. Oxamide Oxamide Oximide Tetrachloride Dichloride Hydrazide and Hydroxyamide of Oxalic Add. Oxalhydrazide, \ CO . NH . NH 2 ' turns brown and decomposes at 235. It is produced by the action of the hydrazine hydrate upon oxalic ester (J. pr. Ch. [2] 51, 194). CONH . OH Hydroxyl Oxamide, ' , melting at 159, is obtained from oxamaethane CONH 2 and hydroxylamine. Acetoxyloxamide, NH 2 . CO . CO . NHO . CO . CH 3 , melts at 173. When heated with acetic anhydride to 110, it is decomposed into cyanuric acid (p. 419), and acetic acid (A. 288, 314). NITRILES OF OXALIC ACID. I Two nitriles correspond to each dicarboxylic acid : a nitrilic acid, or a half-nitrile, and a dinitrile. The nitrilic acid of oxalic acid is Cyancarbonic^ cyanformic, or oxalnitrilic acid. It is only known in its esters. Dicyanogen is the dinitrile of oxalic acid. The kinship of these nitriles to oxalic acid is manifested by their formation from the oxamic esters and oxamide through the elimination of water, and their conversion into oxalic acid by the absorption of water and the splitting-off of ammonia: COOC 2 H 5 _H 3 o COOC 2 H 5 CONH 2 - 2 H 2 O CN CONH 2 "^CN CONH 2 CN Oxamaethane Cyancarbonic Ethyl Ester Oxamide Dicyanogen. Cyancarbonic Esters, Cyanformic Esters, Nitrilo-oxalic Esters, are produced in the distillation of oxamic esters with P 2 O 5 or PC1 5 (p. 435), as well as from cyan- imido-carbonic ether. Cyancarbonic Methyl Ester, CN . CO 2 . CH 3 , boils at 100. Cyancarbonic Ethyl Ester boils at 115- These are liquids with a penetrating odor. DICYANOGEN. 437 They are insoluble in water, which slowly decomposes them into CO 2 , prussic acid, and alcohols. Zinc and hydrochloric acid convert them into glycocoll (p. 354). Concentrated hydrochloric acid breaks them down into oxalic acid, ammonium chloride, and alcohols. Bromine or gaseous HC1 at 100 transforms the ethyl ester into a polymeric, crystalline body, melting at 165, and by the action of cold alkalies yielding salts oi paracyancarbonic acid e.g., (CN . CO 2 K)n. Cyanorthoformic Ester, Triethoxyacetonitrile, Ortho - oxalnitrilic Ethyl Ester, CN . C(OC 2 H 5 ) 3 , boils at 160 (A. 229, 178). Trinitroacetonitrile, CNC(NO 2 ) 3 , melts at 41.5 and explodes at 220 (see fulminuric acid, p. 238). Dicyanogen, Oxalonitrile, [Ethan Dinitrile], NC . CN, is present in small quantity in the gases of the blast furnace. It was obtained in 1815 by Gay-Lussac by the ignition of mercury cyanide. The transposition proceeds more readily by the addition of mercuric chloride : c Hg(CN 2 ) = C 2 N 2 + Hg. Hg(CN) 2 + HgCl 2 = C 2 N 2 + Hg 2 Cl 2 . Silver and gold cyanides deport themselves similarly. Dicyanogen is most readily prepared from potassium cyanide. To this end the concentrated aqueous solution of I part KCN is gradually added to 2 parts cupric sulphate in 4 parts of water. Heat is then applied. At first a yellow precipitate of copper cyanide, Cu(CN) 2 , is pro- duced, but it immediately breaks up into cyanogen gas and cuprous cyanide, CuCN (B. 18, R. 321): 2S0 4 Cu + 4CNK = Cu 2 (CN) 2 + (CN) 2 + 2SO 4 K 2 . Its preparation from ammonium oxalate and oxamide, through the agency of heat, is of theoretical interest. The same may be said of its formation upon passing the induction spark between carbon points in an atmosphere of nitrogen (1859, Morren). Cyanogen is a colorless, peculiar-smelling, poisonous gas. It may be condensed to a mobile liquid by cold of 25, or by a pressure of five atmospheres at ordinary temperatures. In this condition it has a sp. gr. 0.866, solidifies at 34 to a crystalline mass, and boils at 21. It burns with a bluish-purple mantled flame. Water dissolves 4 volumes and alcohol 23 volumes of the gas. On standing the solutions become dark and break down into ammonium oxalate and formate, hydrogen cyanide and urea, and at the same time a brown body, the so-called azulmic acid, C 4 H 5 N 5 O, separates. With aqueous potash cyanogen yields potassium cyanide and isocyanate. In these reactions the molecule breaks down, and if a slight quantity of aldehyde be present in the aqueous solution, only oxamide results. Oxalic acid is produced in the presence of mineral acids, C 2 N 9 -\- 4H 2 O = C 2 O 4 H 2 -{- 2NH 3 . Concentrated hydriodic acid converts it into glycocoll (p. 354). On heating mercuric cyanide there remains a dark substance, paracyanogen, a polymeric modification, (C 2 N 2 )n. Strong ignition converts it again into cyanogen. It yields potassium cyanate with caustic potash. With hydrogen sulphide cyanogen yields hydroflavic acid, C 2 N 2 . H 2 S = i CS .Nx~I 2 , and hydrorubianic acid, C 2 N 2 . 2H 2 S. These two compounds may be considered thioamides. 438 ORGANIC CHEMISTRY. Hydrorubianic acid dissolves with difficulty in chloroform, from which hydroflavic acid crystallizes in yellow, transparent, flat needles, melting with decomposition at 87-89 (A. 254, 262). Hydrorubianic acid consists of yellow-red needles. Primary bases replace the amido-groups by alkylic amido-groups (A. 262, 354). It combines with the aldehydes with the elimination of water (B. 24, 1027). Diamido-oxal ethers result from the action of ammonia upon dichloroxalic esters. They have not yet been obtained in a pure condition. Aniline and dichloroxalether in cold ethereal solution yield Dianilido-oxal ether, CO 2 C 2 H5C(NHC 6 H 3 ) 2 OC 2 H 5 , a thick liquid soluble in ether. At o hydrochloric acid precipitates from this ethereal solution the dichlorhydrate, CO 2 C 2 H 5 C(NHC 6 H 6 . HC1) 2 O . C 2 H 5 . Mixed diamido- ethers can be obtained by allowing anhydrous ammonia gas to act upon a cooled, ethereal solution of monophenylirnido-oxalic acid dimethyl ether. In this way Amido-anilido-oxalic methyl ester, CO 2 CH 3 . C(NH 2 )(NHC 6 H 5 )O . CH 3 , is obtained. It melts at 215. Imido-oxalic Ethers: Monoimido-oxalic Ether, CO 2 C 2 H 5 . C(: NH)- OC 2 H 5 , boiling at 73 (18 mm.), results from the action of a calculated amount of ^ n-hydrochloric acid upon di imido-oxalic ether (A. 288,289). Phenyl-imido-oxal- methyl Ether, CO 2 CH 3 . C( = N . C 6 H 5 )O . CH 3 . Di-imido-oxal- Ether, C 2 H 5 O . (NH)C C(NH) . OC 2 H 5 , melts at 25 and boils at 170. Its hydrochloride is obtained on conducting HC1 into an alcoholic solution of cyanogen (B. n, 1418) (compare pp. 232, 269). Oxalamidine, NH 2 (NH)C C(NH)NH 2 , results from the action of alcoholic ammonia upon the hydrochloride of oximido-ether (B. 16, 1655). HN : C . NH . NH 2 Carbohydrazidine, Oxaldi-imide-dihydrazide, i , white, flat HN: C. NH. NH 2 needles, which assume a reddish-brown color on heating and do not melt at 250. It results from the union of cyanogen with hydrazine. Dibenzal carbohydrazidine melts at 218 (J. pr. Ch. [2] 50,253). Cyanimido-carbonic Ether, Nitrilo-oxal-imido-ether, CN . C( : NH)O . C 2 H 5 , boiling at 50 (30 mm.), is obtained from chlorcyanogen or bromcyanogen, water, alcohol, and potassium cyanide, as well as from aqueous potassium cyanide and ethyl hypo- chlorite (p. 148), when the following intermediate products probably arise : KN:C.O.C 2 H 5 KN:C.OC 2 H 5 H 2 OHN:C.OC 2 H 5 This reaction certainly favors the formula K . N : C for potassium cyanide, because it can not be clearly understood with the formula KCN (A. 287, 273). Cyan-imido- carbonic ether is a yellowish oil, with a sweet and at the same time penetrating odor. Chlorethylimidoformyl Cyanide, Nitril-oxalo-ethyl-imide chloride, CN . C( : NC 2 - H 5 )C1, from chlorcyanogen and ethyl isocyanide (A. 287, 302), boils at 126. Oxaldihydroxamic Acid, [C : (NOH)OH] 2 , melting at 165, results from oxalic ester and hydroxylamine (B. 27, 799, 1105). Oxaldiamidoxime, [C(N. OH)NH 2 ] 2 , melts with decomposition at 196. It is formed when NH 2 OH acts (i) upon cyanogen (B. 22, 1931), (2) upon cyananiline (B. 24, 8oi), (3) upon hydrorubianic acid (B. 22, 2306). Its dibenzoyl derivative melts at 222 (B. 27, R. 736). Chloro-oximido-acetic Ester, Ethoxalo-oxime Chloride, CO 2 C 2 H 5 . C( : NOH)C1, melting at 80, is obtained from chloracetoacetic ester by means of fuming nitric acid, and when concentrated hydrochloric acid acts upon nitrol-acetic ester (B. 28, 1217). Nitrol-acetic Ester, Ethoxal-nitrolic Acid, CO 2 C 2 H 5 . C( : NOH) . NO 2 , from iso- nitroso-acetoacetic ester and nitric acid of sp. gr. 1.2 (B. 28, 1217), melts at 69. Formazyl Carbonic Acid, CO 2 H . C<^J ~ NHC^H ' melts ' whenra P idl y neated at 162. It is produced when its ester is saponified. The ester results from the action of diazo-benzene chloride (i) upon the hydrazone of mesoxalic ester, (2) upon sodium malonic ester, and (3) upon acetoacetic ester. Oxalic acid breaks down into MALON1C ACID. 439 formic acid and CO 2 , and formazyl carbonic acid decomposes into formazyl hydride (p. 233) and C0 2 (B. 25, 3175, 3201). Parabanic acid and oxaluric acid are ureides of oxalic acid. They will be con- sidered together with the derivatives of uric acid (see these). THE MALONIC ACID GROUP. Malonic Acid \Propan Diacid^ CH 2 (CO 2 H) 2 , melts at 132. It occurs as calcium salt in sugar-beets, (i) The acid was discovered in 1858, by Dessaignes, on oxidizing malic acid, CO 2 H. CH(OH) . CH 2 - CO 2 H, with potassium bichromate (hence the name, from malum, apple) and quercitol with potassium permanganate (B. 29, 1764). It is also (2) produced in the oxidation of hydracrylic acid, and (3) of propylene and allylene by means of KMnO 4 . . (4) Kolbe and Hugo Muller obtained it almost simultaneously (1864) by the conversion of chloracetic acid into cyanacetic acid, the nitrile acid of malonic acid, and then saponifying the latter with caustic potash. (5) By the de- composition of barbituric acid or its malonyl urea (see this). (6) Malonic ester and CO are formed in the distillation of oxalacetic ester (see this) under the ordinary pressure (B. 27, 795). Preparation. One hundred grams of chloracetic acid, dissolved in 200 grams of water, are neutralized with sodium carbonate (no grams), and to this 75 grams of pure, pulverized potassium cyanide are added, and the whole carefully heated, after solu- tion, upon a water-bath. The cyanide produced is saponified either by concentrated hydrochloric acid or potassium hydroxide (B. 13, 1358; A. 204, 225). To obtain the malonic ester directly, evaporate the cyanide solution, cover the residue with absolute alcohol and lead HC1 gas into it (A. 218, 131), or treat it with sulphuric acid and alcohol (C. 1897, I, 282). Properties. Malonic acid crystallizes in triclinic plates. It is easily soluble in water and alcohol. Above its melting point it decomposes into acetic acid and carbon dioxide. Bromine in aqueous solution converts it into tribromacetic acid and CO 2 , while iodic acid changes it to di- and tri-iodoacetic acid (p. 275) and CO 2 . Salts. Barium salt, (C 3 H 2 O 4 )Ba + 2H 2 O. The calcium salt, C 3 H 2 - O 4 Ca) -f- 2H 2 O, dissolves with difficulty in cold water. The silver salt, C 3 H 2 Ag 2 O 4 , is a white, crystalline compound. Ester. Potassium ethyl malonate, from the ester and caustic potash, yields ethylene succinic ester when it is electrolyzed (pp. 430, 443). The neutral malonic esters are made by treating potassium cyan- acetate or malonic acid with alcohols and hydrochloric acid. These compounds are of the first importance in the synthesis of the polycarboxylic acids, because of the replaceability of' the hydrogen atoms of the CH 2 -group by sodium. History. This property was first observed in 1874 by van t'Hoff, Sr. (B. 7, 1383), and the- possibility of obtaining the malonic acid homologues, by means of it, was indicated. The comprehensive, exhaustive experiments begun in 1879 by Conrad 44 ORGANIC CHEMISTRY. first demonstrated that malonic esters were almost as valuable as the acetoacetic esters in carrying out certain synthetic reactions (pp. 371, 376) (A. 204, 121). The methyl ester, CH 2 (CO 2 . CH 3 ) 2 , boils at 181. The ethyl ester boils at 198 ; its specific gravity at 18 is 1. 068. By the action of sodium ethylate upon it the Na- compounds, CHNa(CO 2 .C 2 H 5 ) 2 and CNa 2 (CO 2 . C 2 H 5 ) 2 (B. 17, 2783; 24, 2889 Anm.), result. Malonic ester is not soluble in aqueous alkalies. Iodine converts both sod-malonic esters into ethane and ethylene tetracarboxylic esters. Sodium malonic ester, when electrolyzed, yields ethane tetracarboxylic ester (B. 28, R. 450). Alkyl haloids convert the sodium malonic esters into esters of malonic acid homo- logues (B. 28, 2616). The malonic esters and diazobenzene chloride yield phenyl- hydrazone mesoxalic esters (see these). Upon heating sodium malonic ester to 145 a condensation of 3 molecules occurs, with a splitting-off of 3 molecules of alcohol, and there remains the ester of trisod-phloroglucin tricarboxylic acid (a derivative of benzene) (B. 18, 3458): 3 CHNa(C0 2 C 2 H 5 ) 2 = C 6 O 3 Na s (CO 2 . C 2 H 5 ) 3 + 3 C 2 H 5 OH. The malonic esters and diazobenzene chloride yield phenylhydrazone -mesoxalic esters (see these). Malonic Anhydride, CH 2 <^/-.Q>O, is not known (comp. p. 428). Malonic Acid Chlorides : Chloride of Ethyl Malonic Ester, CO 2 . C 2 H 5 . CH 2 COC1, obtained from potassium ethyl malonate by the action of PC1 5 , boils at 170-180 (B. 25, 1504). Malonyl Chloride, CH 2 (COC1) 2 . produced when SOC1 2 acts upon malonic acid (B. 24, R. 322), boils at 58 (27 mm.). Malonamic Ethyl Ester, CO 2 C 2 H 5 . CH 2 . CO . NH 2 , melting at 50, is formed upon heating the hydrochloride of mono-imido-malonic ester (B. 28, 479). Malonamide, CH 2 (CONH 2 ) 2 , melts at 170 (B. 17, 133). Imidomalonamide, NH 2 . CO. CH 2 .- C(:NH)NH 2 . Malonhydrazide, CH 2 (CO . NH . NH 2 ) 2 , melts at 152 (J. pr. Ch. [2] 51, 187). Nitriles of Malonic Acid: Cyanacetic Acid, Nitrilomalonic Acid, half nitrile of malonic acid, CN . CH 2 . CO 2 H (p. 439), melts at 70 (B. 27, R. 262). It dissolves very readily in water, and at about 1 65 breaks down into CO 2 and acetonitrile (p. 268). Cyanacetic Ethyl Ester, CN . CH 2 . CO 2 . C 2 H 5 , boiling at 207, forms sodium deriva- tives like malonic ester, by means of which the hydrogen of the CH 2 -groups can be replaced by alkyls (B. 20, R. 477) and acid radicals (B. 21, R. 353). Cyanacetam- ide, CN.CH 2 . CONH 2 , from the ester and ammonia, melts at 118. Cyanacethydra- zide, CNCH 2 CO . NHNH 2 , melts at 114 (J. pr. Ch. [2] 51, 186). Malononitrile, CH 2 < N , methylene cyanide, is obtained by distilling cyanacet- amide with P 2 O 5 (C. 1897, I, 32). It is soluble in water. Silver nitrate precipi- tates CAg 2 (CN) 2 from the aqueous solution (B. 19, R. 485). Hydrazineand malono- nitrile yield diamidopyrazole, C 3 N 2 H 2 (NH 2 ) 2 (B. 27, 690). See also cyanoform. Methenylamidoxime-acetic Acid, NH 2 (HON) : C . CH 2 . CO 2 H, melts at 144 (B. 27, R. 261). Nitrilomalonimidoxime, Cyanethenylamidoxime, CN . CH. 2 . C ( : N .- OH)NH 2 , melts at 124-127. Malondihvdroxamic Acid, CH 2 [C( : NOH)OH] 2 , melts at 154 (B. 27, 803). Malondiamidoxime , CH 2 . [C( : N . OH)NH 2 ] 2 , melts at 163-167 (B. 29, 1168). The ureides of malonic acid will be treated later in connection with uric acid (see this). Halogen Malonic Acids are produced when chlorine and bromine act upon malonic acid and malonic esters (B. 21, 1356). Chlormalonic Ester, CHC1(CO 2 . C 2 H 5 ) 2 , boils at 222. Brom-malonic Ester boils with decomposition at 235 (B. 24, 2993, 2997 ; compare also tartronic acid]. Brom-malononitrile melts at 65 (C. 1897, I, 32). Dichlormalonic Ester, CC1 2 (CO 2 - C-jH^, boils at 231-234. Dibrom-malonic Acid melts at 126. Dibrom-malono- nitrile melts at 109 (C. 1897,1,32). Dibrom-malonic Ester boils at 145 to 155 ALKYLIC MALONIC ACIDS. 441 (25 mm.) (B. 24, 3001 ; compare also mesoxalic acid). The mono- and dichlor- or brom malonic acids link malonic acid to tartronic (p. 485) and mesoxalic acids (P- 497)- Alkylic Malonic Acids. The general methods suitable for the preparation of alkylic malonic acids are (i) reaction 50 (p. 430), con- version of a-halogen fatty acids into a-cyan-fatty acids the half nitriles of the malonic acid homologues; and (2) reaction 6 (p. 430), the re- placement of the hydrogen atoms of the CH 2 group in the malonic esters by alkyls. First, with the aid of sodium ethylate, mono-sod- malonic esters are made, which alkyl iodides convert into mono-alkylic malonic esters. These are further able to yield monosodium alkylic malonic esters, which alkylogens change to dialkylic malonic esters e. g. : C0 2 C 2 H 5 - j(CH s ) t C0 2 C 2 H 5 Dimethyl Malonic Ester. It has been previously mentioned under acetoacetic ester (p. 373) that the reaction consisted in the addition of sodium ethylate to the carboxethyl group, with the split- ting-off of alcohol and the production of a double union, to which the alkylogen at- tached itself, and there then followed the elimination of a sodium halide (A. 280, 264): CO,C,H 5 C0 2 .C 2 H 5 CH 2 C0 2 .C 2 H 5 Malonic Ethyl Ester C0 2 C 2 H 5 ^CHNa C0 2 C 2 H 5 Sodium Malonic Ester C0 2 C 2 H 5 ->CH . CH 3 C0 2 C 2 H 5 Methyl Malonic Ester C0 2 C 2 H 5 ^CNa.CH 3 - C0 2 C 2 H 5 Sodium Methyl Malonic Ester Some of these dialkylic malonic acids are formed when complex carbon derivatives are oxidized e. g, , dimethyl malonic acid results from the oxidation of unsymmet- rical dimethyl ethylene succinic acid, mesitonic acid, camphor, etc. The production of dimethyl malonic acid in this manner proves the presence, in these bodies, of the atomic grouping All mono- and dialkylic malonic acids, when exposed to heat, split off CO* and pass into mono- (B. 27, 1177) and dialkylic acetic acids (p. 428). See Z. phys. Ch. 8, 452, for the affinity magnitudes of the alkylic malonic acids. Consult B. 29, 1864, upon the speed of saponification of the alkylic malonic esters. Iso-succinic Acid, Ethidene Succinic Acid, Methyl Malonic Acid [Methyl propan di-acid], melts at 130 with decomposition. It is isomeric with ordinary succinic acid or ethylene succinic acid (p. 431), and is obtained (i) from a-chlor- and a-brom-propionic acids through the cyanide (B. 13, 209), and (2) from sodium malonic ester and methyl iodide. 442 ORGANIC CHEMISTRY. When ethidene bromide, CH 3 . CHBr 2 , is heated with potassium cyanide and alkalies, we do not obtain ethidene succinic acid by the operation, but by molecular rearrangement, ordinary ethylene succinic acid. The acid is more soluble than ordinary succinic acid in water. If heated above 130, it breaks up into carbon dioxide and propionic acid (p. 246). The ethyl ester boils at 196 ; the methyl ester at 179. a-Cyanpropionic Ester, CH 3 . CH(CN)CO 2 C 2 H 5 , boils at 197-198. Bromisosuccinic Acid, CH 3 . CBr(CO 2 H) 2 , melts at 118-119 ( B - 2 3> R - II 4)- Methyl Brom-malonic Ester boils at 115-118 (15 mm.) (B. 26, 2356). Ethyl Malonic Acid, C 2 H 5 . CH(CO 2 H) 2 , melts at 111.5. The ethyl ester boils at 200. Ethylbrommalonic Ester boils at 125 (10 mm.) (B. 26, 2357). Dimethyl Malonic Acid, (CH 3 ) 2 C(CO 2 H) 2 , melts at 117 ; the ethyl ester boils at 195. The nitrile melts at 32 and boils at 64 (22 mm.). Compare the 3d method of formation as given above. Both acids are isomeric with pyrotartaric acid and ri-glutaric acid (see p. 431). In the case of the subjoined alkylic malonic acids, the boiling points of the ethyl esters (inclosed in parentheses) are given, together with the melting points of the acids. Propylmalonic Acid, CH 3 . CH 2 . CH 2 CH(CO 2 H) 2 , melts at 96 (219-222). Isopropylmalonic Acid, (CH 3 ) 2 . CH . CH(CO 2 H) 2 , melts at 87 (213-214). Methyl-ethyl Malonic Acid, CH 3 (C 2 H 5 )C(CO 2 H) 2 , melts at 118 (207-208). These three acids are isomeric with adipic acid, methyl glutaric acid, ethyl and dimethyl succinic acids (see p. 431). Norm. Bulylmalonic Acid, CH 3 (CH 2 ) 3 . CH(CO 2 H) 2 , melts at 101.5. Isobutyl- Malonic Acid melts at 107 (225). Sec. Butyl Malonic Acid, CH 3 (C 2 H 5 )CH . CH- (CO 2 H) 2 , melts at 76 (233-234). Propylmethyl Malonic Acid, CH 3 (CH 3 . CH 2 . CH 2 )C(CO 2 H) 2 , melts at 106-107 (220-223). Isopropylmetkyl Malonic Acid r&tfa at 124 (221). Diethylmalonic Acid melts at 1 21 (A. 292, 134). Diethy I malonic Nitrile melts at 44 and boils at 92 (24 mm.). Pentylmalonic Acid, CH 3 (CH 2 ) 4 CH(CO 2 H) 2 , melts at 82. Dipropylmalonic Acid, (CH 3 . CH 2 . CH 2 ) 2 C(CO 2 H) 2 , melts at 158. Cetylmalonic Acid, CH 3 (CH 2 ) 15 - CH(CO 2 H) 2 , melts at 121.5-122 (A. 204, 130; 206, 357 ; B. 24, 2781). THE ETHYLENE SUCCINIC ACID GROUP. Ethylene succinic acid and its alkylic derivatives, as mentioned in the introduction, are characterized by the fact that when heated they break down into anhydrides and water. The anhydride formation takes place more readily in the alkylic succinic acids, the more hydro- gen atoms of the ethylene residue of the succinic acid are replaced by alkyl radicals. The alkylic succinic acids form anhydrides more readily with acetyl chloride, and are more volatile in aqueous vapor than their isomeric alky 1-n -glutaric acids (A. 285, 212). The sym. dialkylic succinic acids show remarkable isomeric phenomena, which will be more fully explained under the symmetrical dimethylsuccinic acids (p. 444). The following are characteristics of a succinic acid : (i) the an- "hydride ; (2) the anilic acid, which appears in the chloroform, ethereal, or benzene solution of the anhydride ; (3) the anil produced by heat- ing the anilic acid, or by the action of phosphorus pentachloride or acetyl chloride upon it (A. 261, 145 ; 285, 226). ETHYL SUCCINIC ACID. 443 Ordinary Succinic Acid, or ethylene dicar boxy lie acid, CO 2 H .- CH,. CH 2 . CO 2 H, melting at 185, is isomeric with methylmalonic acid, or isosuccinic acid (p. 441). It occurs in amber, in some varieties of lignite, in resins, in turpentine oils, and in animal fluids. It is formed in the oxidation of fats with nitric acid, in the fermentation of calcium malate or ammonium tartrate (A. 14, 214), and in the alcoholic fermentation of sugar. In the general methods of formation given on p. 430, ethylene succinic acid has been in part the chosen example. It is produced (i) by the oxidation of f-butyrolactone. (2) By the reduction of fumaric and maleic acids with nascent hydrogen. (3) By reducing (a) malic acid (oxysuccinic acid) and tartaric acid (dioxysuccinic acid) with hydriodic acid, or by the fermentation of these bodies; (<) by the action of sodium amalgam upon halogen succinic acids. It is a nucleus-synthetic product obtained (4) by the action of finely divided silver upon brom-acetic acid. The yield is small. (50) By converting /9-iodpropionic acid (p. 275) into cyanide and decomposing the latter with alkalies or acids. (5^) M. Simpson, in 1861, was the first to prepare it synthetically from ethylene, by con- verting the latter into cyanide. Succinic acid is formed on boiling its dinitrile with caustic potash or mineral acids : CH 2 . OH CH 2 CH 2 Br CH 2 CN CH 2 . CO 2 H CH 3 ^CH 3 ~~ ^CH 2 Br~ ^ CH 2 CN~ ^ CH 2 . CO 2 H. Ethidene chloride and potassium cyanide also yield ethylene cyanide (p. 441). (6) The electrolysis of potassium ethyl malonic ester (p. 440) pro- duces succinic ester. (7) By the decomposition of aceto-succinic esters, (8) of ethane- tricarboxylic acid, (9) of sym. ethane tetracarboxylic acid. Succinic acid crystallizes in monoclinic prisms or plates, and has a faintly acid, disagreeable taste. It melts at 180 (185) and distils at 235, at the same sime decomposing partly into water and succinic anhydride. At the ordinary temperature it dissolves in 20 parts of water. Uranium salts decompose aqueous succinic acid in sunlight into propionic acid and CO 2 . The galvanic current decomposes its potas- sium salt into ethylene, carbon dioxide, and potassium (p. 90). Paraconic Adda, } -lactone carboxylic acids, are formed when sodium succinate is heated with aldehydes and acetic anhydride (Fittig, A. 255, i). When succinic acid, zinc chloride, sodium acetate, and acetic anhydride are heated to 200, small quantities of ou / -dimethyl-3-acetyl pyrrol (B. 27, R. 405) are produced. When calcium suc- cinate is distilled, p-diketo-hexamethylene is produced in small quantities (B. 28, 738). Salts, succinates : The calcium salt, C 4 H 4 O 4 Ca, separates with 3 molecules of H 2 O from a cold solution, but when it is deposited from a hot liquid it contains only 444 ORGANIC CHEMISTRY. lH 2 O. When ammonium succinate is added to a solution containing a ferric salt, all the iron is precipitated as reddish-brown basic ferric succinate (separation of iron from aluminium). When potassium ethyl succinate is electrolyzed, it yields adipic ester (p. 454). Methyl Succinic Ester, C 2 H 4 (CO 2 . CH 3 ) 2 , melts at 19, and boils at 80, under a pressure of 10 mm. Ethyl Succinic Ester boils at 216. Sodium converts them into succino-succinic ester : C0 2 . CH 3 ~CH CO . GH 2 CH 2 CO CHC0 2 CH S CO Ethylene Succinic Ester, C 2 H 4 <^Q 2 >C 2 H 4 , fuses at 90. Mono-alkylic Succinic Acids. Pyrotartaric Acid, Methyl .. CH 3 .CH.CO 2 H Succinic Acid, ' i . melts at 112. It was first obtained CH 2 . CO 2 H in (i) the dry distillation of tartaric acid. It may be synthetically prepared (2) by heating pyroracemic acid, CH 3 . CO . CO 2 H, alone to 170, or with hydrochloric acid to 100 ; (3) by the action of nascent hydrogen upon the three isomeric acids: ita-, citra-, and mesa-conic acids : C 5 H 6 O 4 -(- H 2 = C 5 H 8 O 4 ; (4) from /3-brombutyric acid and propylene bromide by means of the cyanide; (5) from a- and /9- methyl aceto-succinic esters; and (6) from a- and /3-methyl ethane tri- carboxylic acid. The acid dissolves readily in water, alcohol, and ether. When quickly heated above 200 it decomposes into water and the anhydride. If, however, it be exposed for some time to a tem- perature of 200-210, it splits into CO 2 and butyric acid. It suffers the same decomposition when in aqueous solution, if acted upon by sunlight in presence of uranium salts (B. 24, R. 310). Strychnine resolves it into its optically active components (B. 29, 1254). Potassium Salt, C 5 H 6 O 4 K 2 . The calcium salt, C 5 H 6 O 4 Ca -f- 2H 2 O, dissolves with difficulty in water. The methyl ester boils at 153 (20 mm. ). The ethyl ester boils at 160 (22 mm.). The dimethyl ester boils at 197. The diethyl ester boils at 218 (B. 26, 337 ). Ethyl Succinic Acid, CO 2 H . CH 2 . CH(C 2 H 5 )CO 2 H, melts at 98. n-Propyl Succinic Ester, CO 2 H . CH 2 . CH(C 3 H 7 )CO 2 H, melts at 91 (A. 292, 137). Pimelic Acid, Isopropy 'I Succinic Acid, (CH 3 ) 2 . CH . CH<^ CO 2 H , was first prepared by fusing camphoric acid and tanacetogen dicarboxylic acid (B. 25, 3350) with caustic potash. It may be synthetically obtained from acetoacetic or malonic esters (A. 292, 137), as well as from the products of the action of potassium cyanide upon isocaprolactone at 280 (C. 1897, I, 408). It melts at 114. Svmm. Dialkylic Succinic Acids, CO 2 H . CHR' CHR' . CO 2 H. Symmetrical dimethyl succinic acid exists, like the other symmetrical disubsti- tuted succinic acids, e.g., dibrom-succinic acid (p. 451), diethyl-, methyl-ethyl-, di- isopropyl-, and diphenyl-succinic acids, in two different forms, having the same struc- tural formulas. Dioxysuccinic acid or tartaric acid occurs in two active and two inactive forms (one is decomposable and the other is not), which are satisfactorily explained by van t' Hoff ' s theory of asymmetric carbon atoms (p. 49). The pairs of isomeric UNSYM. DIALKYLIC SUCCINIC ACID. 445 dialkylic succinic acids, also containing asymmetric carbon atoms, manifest certain analogies with para- tartaric acid (racemic acid), and anti- or 7^tt?-tartaric acid. Hence it is assumed that their isomerism is due to the same cause. The higher melting, more difficultly soluble modification is called the/>#rrt-form, while the meso- or anti-form is more readily soluble, and melts lower (Bischoff, B. 20, 2990; 21, 2106). However, this assumption is doubtful, inasmuch as not one of the constantly inactive dialkylic succinic acids has ever been converted into an active variety (B. 22, 1819). Bischoff has set forth a theory of dynamical isomerism (B. 24, 1074, 1085) in which he presents views in regard to the equilibrium positions of the atoms and radicals, joined to the two asymmetric carbon atoms, in the symmetrical dialkylic succinic acids. These (their esters) are produced as follows : By the saponification of dimethyl- ethane tricarboxylic esters with hydrochloric acid ; from dimethyl aceto-succinic ester by the elimination of the acetyl group ; by heating a-halogen fatty-acids with re- duced silver (B. 22, 60), or more readily by the action of potassium cyanide upon a-monohalogen fatty-acids (B. 21, 3160) ; by the reduction of dialkylic malei'c anhy- drides, pyrocinchonic acid (p. 466), with sodium amalgam or hydriodic acid (B. 20, 2 737 > 2 3. 644). Both symmetrical dimethyl succinic acids are produced in all of these syntheses. They are separated by crystallization from water. Sym. Dimethylsuccinic Acids, CO 2 H . CH(CH 3 ) CH(CIi 3 )CO 2 H. The /ar CH 2 . CO >Q PCI, > CH 2 . CCl 2 CH 2 .COOH CH 2 .CO CH 2 .CO This latter view would make succinyl chloride a dichlor-substitution product of butyrolactone , into which it passes on reduction. The behavior of succinyl chloride toward zinc ethide is in harmony with its lactone formula, for it then yields y-diethyl- butyrolactone (p. 345), and in the presence of benzene and aluminium chloride it chiefly affords y-diphenylbutyrolactone (B. 24, R. 320). Ten per cent, of sym. dibenzoyl ethane, C 6 H 5 CO . CH 2 . CH 2 . CO . C 6 H 5 , is produced at the same time. Probably succinyl chloride is also a mixture of much y-dichlorbutyrolactone and a little [butandiacid chloride], C1CO . CH 2 . CH 2 . COC1. Pyrotartryl Chloride, C 5 H 6 O 2 C1 2 , boils at 190-195 (B. 16, 2624). Unsym. Dimethylsuccinyl Chloride, C 6 H 8 O 2 . C1 2 , boils at 200-202 (A. 242, 138, 207). Anhydrides of the Ethylene Succinic Acid Group. The easy anhydride formation is characteristic of ethylene succinic acid and its alkylic derivative. It proceeds the more readily the more the hydrogen atoms of the ethylene group are replaced by alcohol radicals (p. 442). Formation. (i) By heating the acids alone. (2) By the action of P 2 O 5 (B. 28, 1289), PC1 5 or POC1 3 (A. 242, 150) upon the acids. (3) By treating the acids with the chloride or anhydride of a monobasic SUCCINIC ACID GROUP. 447 fatty acid, e. g., acetyl chloride or acetic anhydride (Anschiitz, A. 226, i) : CH 2 . COOH CH 2 CO CH 3 . CO cX. COOH + 2CH " COC1 - dH|co> + d H |. eo> + 2HC1 ' (4) When the chloride of a dicarboxylic acid acts (a) upon the acid, or (&) upon anhydrous oxalic acid (A. 226, 6) : CH 2 . CCL COOH CH 2 CO dnl.co > + dam " dH; C o> + 2HCI + co + co " CH 2 CO Succinic Anhydride, I ^>O, melts at 120 and boils at 261. Methyl CH 2 CO Succinic Anhydride, or pyrotartaric anhydride, melts at 31.5-32 and boils at 247. Ethyl Succinic Anhydride boils at 243. Isopropyl Succinic Anhydride boils at 250. Para- and Meso-s-dimethyl Succinic Anhydride melt at 38 and 87, respectively (B. 26, 1460). Meso-s-methyl-ethyl- and Meso-s-diethyl Succinic Anhydrides melt at 244-245 and 245-246. Unsym. Dimethyl Succinic Anhydride melts at 29 and boils at 219-220. Trimethyl Succinic Anhydride melts at 31 and boils at 231 (760 mm.); loi. (12 mm.). Tetramethyl Succinic Anhydride melts at 147 and boils at 230.5. Properties and Behavior. Succinic anhydride has a peculiar, faint, penetrating odor. It can be recrystallized from chloroform. It reverts to succinic acid in moist air. The conversion is more rapid if it is boiled with water. It yields succinic alkyl ester acids with alcohols. Ammonia and amines change it to succinamic and alkyl succinamic acids. PC1 3 changes it to succinyl chloride. Sodium amalgam reduces it to butyrolactone (B. 29, 1193). If the anhydride is boiled for some time it loses CO 2 and changes to the dilactone of acetone diacetic acid, CO(CH 2 . CH 2 .- CO 2 H) 2 (see this). P 2 S 3 converts succinic acid and sodium succinate into thiophene, CH =: CH S CH = CH (see this). The reactions of very few of the homo- logues of succinic anhydride have thus far been accurately studied. They are similar to those of the latter. 00 CH 2 .CO.O CH 2 .C\ Peroxides : Succinyl Peroxide, \ i or i }O, is a white, crys- CH 2 . CO . O CH 2 .CO/ talline body. It explodes below 100 if rapidly heated. It is formed by energeti- cally shaking equimolecular quantities of succinyl chloride and sodium peroxide (B. 29, 1724). NITROGEN-CONTAINING DERIVATIVES OF THE ETHYLENE SUCCINIC ACID GROUP. Ethylene succinic acid, like oxalic acid, yields an imide, a diamide, a nitrile acid and a dinitrile : CH 2 .C0 2 H CH 2 .CO CH 2 .CO.NH 2 CH 2 .CO 2 H CH 2 .CN CH 2 .CONH 2 CH 2 .CO CH 2 .CO.NH 2 CH 2 . CN CH 2 .CN Succinamic . Succitiimide Succinamide /3-Cyanpropionic Ethylene Acid Acid Cyanide. (a) Amic Acids. Most of these have been prepared by decomposing the imides with alkalies or baryta water. They are also formed on adding ammonia, primary 44 ORGANIC CHEMISTRY. aliphatic amines (and aromatic amines, e. g., aniline and phenylhydrazine) to acid anhydrides. They behave like oxamic acid (p. 435). When heated, or when treated with dehydrating agents, e.g., PC1 5 or CH 3 . COC1, they become imides, which bear the same relation to them that the anhydrides sustain to the dicarboxylic acids. Succinamic Add, CO 2 H . CH 2 . CH 2 . CONH 2 , is obtained from succinimide by the action of baryta water. Succinethylamic Add, CO 2 H . CH 2 . CH 2 . CONHC 2 H 5 (A. 251, 319). Succinalic Add, CO 2 H . CH 2 . CH 2 . CONHC 6 H 5 (B. 20, 3214). Unsym. Dimethyl Sucdnalic Add melts at 189. () Imides. These are produced (i) on heating the acid anhy- drides in a current of ammonia; (2) when the ammonium salts, cli- amides and amic acids are heated. They show a symmetrical structure, as will be explained in connection with succinanil. Succinimide, J *'^>NH, melting at 126 and boiling at 288, V-'Jtirt V^v/ crystallizes with water, and manifests the character of an acid, as the hydrogen of the NH-group can be replaced by metals. Potassium Succinimide, C 2 H 4 (CO) 2 NK ; Sodium Succinimide (B. 28, 2 353) j Silver Succinimide (A. 215, 200) ; Potassium Tetrasuccinimide- tri-iodo-iodide, (C 4 H 5 O 2 N) 4 I 3 . KI (B. 27, R. 478; 29, R. 298). The cyclic imides are readily broken down by alkalies and alkaline earths : CH 2 . CO T Ho CH 2 . CO 2 H CH 2 . C0 > "^C H 2 . CONH 2 * On distilling succinimide with zinc dust, oxygen is withdrawn and pyrrol (see this) is formed. Pyrrolidine, C 4 H 9 N (B. 20, 2215), is formed in the action of sodium upon succinimide dissolved in absolute alcohol : CH = CH Zn CH, . CO Na CH 9 . CH NH -te=r NH -*^ ck;.c H Pyrrol Succinimide Pyrrolidine. . Hypochlorous acid, and hypobromous acid acting on succinimide, and iodine upon silver succinimide produce : Sucdnchlorimide, C 2 H 4 (CO) 2 NC1, melting at 148 ; suc- dnbrominiide, C 2 H 4 (CO) 2 NBr, melting at 173-175 with decomposition, and suc- dniodo-imide (B. 26, 985). Phosphorus pentachloride converts succinimide into CC1 . CO dichlormaleln-imide chloride, II >NH ; pentachlorpyrrol, C 4 C1 5 N, and the V>\^1 . V^V^-lrt heptachloride, C 4 C1 7 O (A. 295, 86). Bromine and caustic potash convert succinimide into /3-amido-propionic acid (p. 358). Sodium methylate changes succinbromimide by a molecular rearrangement into carbmethoxy-$-amidopropionic ester, CH 3 O.- CO . NH . CH 2 . CH 2 . CO 2 . CH 3 , melting at 33.5 (B. 26, R. 935). Methyl Succinimide, C 2 H 4 <^>N .CH 3 , melts at 66.5 and boils at 234. It is obtained from the oxime of laevulinic acid (p. 379) by the action of concen- trated sulphuric acid (A. 251, 318). CO Ethyl Succinimide, C 2 H 4 <^>N. C 2 H 5 , melts at 26 and boils at 234. It is formed when ethyl iodide acts upon potassium succinimide. It yields ethyl pyrrol when it is distilled with zinc dust. Isopropyl Sucdnimide melts at 6l and boils at 230. Isobutyl Succinimide melts at 28 and boils at 247 (B. 28, R. 600). SUCCINO-NITRILE. 449 Phenyl Succinimide y Succinanil, C 2 H 4 (CO) 2 . N . C 6 H 5 , melting at 150, is con- CC1 CO verted by PCI. into dichlormaleic-anil-dichloride, \\ >NC 6 H 5 , the lactam of CC1 CCL CC1 = CC1 y-anilido-perchlorcrotonic acid and tetrachlorphenyl pyrrol, i >NC 6 H-. CCI = CC1 This last fact, and the reduction of dichlormaleic dichloride to y-anilido-butyrolactam or n-phenyl butyrolactam, i 2 ' >NC 6 H 5 , indicate that the symmetrical for- CH 2 . CH 2 mula properly falls to both succinanil and succinimide (A. 295, 39, 88). Unsym. Dimethyl Succinanil melts at 85. Trimethyl Succinanil melts at 129. Tetramethvl Succinanil melts at 88 (A. 285, 234; 292, 184, 176). v-Anilido-sticcinimide, C 2 H 4 (CO) 2 N NHC 6 H 5 , melts at 155 (J. pr. Ch. [2], 35, 293). r^w r^TT c*c\ Pyrotartrimide, ' i >NH, melts at 66. s-Dimethyl Succinimide (B. CH 2 . CO 22, 646). Unsym. Dimethyl Succinimide, melting at 106, is produced by oxidizing mesitylic acid (see this) (A. 242, 208 ; B. 14, 1075). Pimelimide melts at 60 (A. 220, 276). (c] Diamides and Hydrazides. Succinamide, C 2 H 4 <^Q ' NH 2 , is produced like oxamide. It crystallizes from hot water in needles. At 200 it decomposes into ammonia and succinimide. Succindibrom-diamide, NH 2 CO[CH 2 ] 2 CONBr 2 , is obtained from succinamide and BrOK (see also /Mactyl urea, p. 402). Pyrotartramide melts at 225 (B. 29, R. 509). 190). . y 509). Sucdnh y drazide ' melts at l6 7 (J- P r - Ch - y~iT_T (//) Cyclic Diamides. Succinyl Ethylene Diamide, \ ' v v-'irio CxV-'iN Jri . V-xJrlrt (B. 27, R. 589). Succinphenylhydrazide, i-Phenyl-3.6-orthopiperazone, L , melting at 199. is obtained from the hydrochloride Crl 2 . CO . iN hi of phenylhydrazine and succinyl chloride (B. 26, 674, 2181). (^) Nitriles. Nitrite acids have not been studied to any great ex- tent. Certain dinitriles have been prepared by the action of potassium cyanide upon alkylen bromides, the addition-products, formed by the union of bromine with the defines. By absorbing water these di- nitriles become the ammonium salts of the corresponding acids, the synthesis of which they thus facilitate. When reduced, they take up eight atoms of hydrogen and become the diamines of the glycols e. g. : 2 CH, CH 2 .C0 2 H _ _ > (^ CQ^ CHBr CH 2 . CN { _ CH 2 .CH 2 .NH 2 CH 2 . CH 2 .NH 2 Succino-nitrile, Ethylene Cyanide, CN . CH 2 . CH 2 . CN, melt- ing at 54.5, and boiling at 158-160 (20 mm.), is amorphous, trans- parent, readily soluble in water, chloroform and alcohol, but spar- 38 45 & ORGANIC CHEMISTRY. ingly soluble in ether. It is also obtained by the electrolysis of potas- sium cyanacetate (p. 76). It yields ethylene succinic acid when saponified, and tetramethylene diamine upon reduction. It combines with 4HI (B. 25, 2543). Paraformaldehyde, glacial acetic acid and sulphuric acid convert it into methylene succinimide, (C 2 H 4 . C 2 O 2 N) 2 CH 2 , melting above 270 (J. pr. Ch. [2], 50, 3). (/) Oximes.Succinylhydroxamic Add, CO 2 H . CH 2 . CH 2 . C( : N . OH) OH (B. 28, R. 999). Succinylhydroxamic Tetracetate, AcO(AcON : )C . CH 2 . CH 2 . - C( : N . OAc)OAc, melts at 130 (B. 28, 754). Hydroxylamine converts suc- CH 2 . C( : NOH) cinonitrile into succinimidoxime, \^ CQ >NH, melting at 197 (B. 24, CH 2 '. C( : NOH) 3427) and succinimide dioxime, \ ' >NH, melting at 207 (B. 22, CH 2 . C( : NOH) 2964). Pyrotartaronitrile melts at 12 (A. 182, 327 ; B. 28, 2952). Unsym. Dimethylsuccinonitrile, CN . CH 2 . C(CH 3 ) 2 . CN, boils at 218-220 (B. 22, 1740). HALOGEN SUBSTITUTION PRODUCTS OF THE SUCCINIC ACID GROUP. The monosubstitution products are obtained (l) by the direct action of halogens upon the acids, their esters, chlorides or anhydrides. In case of the acids, it is ad- visable to act upon them with amorphous phosphorus and bromine (B. 21, R. 5) ; (2) by the addition of an halogen hydride to the corresponding unsaturated dicar- boxylic acid of the fumaric and malelc group (A. 254, 161) ; (3) by the action of an halogen hydride and (4) of PC1 5 or PBr 5 upon the corresponding a-monoxyethylene dicarboxylic acids (A. 130, 21 ) ; (5) from amido-succinic acids by means of potas- sium bromide, sulphuric acid, bromine and nitric oxide (B. 28, 2769). Inactive chlorsuccinic acid, CO 2 H . CHC1 . CH 2 . CO 2 H, from fumaric acid and hydrochloric acid, melts at 151.5 to 152. The dimethyl ester boils at 106.5 (14 mm.). The diethyl ester boils at 122 (15 mm.). The anhydride melts at 40-41 and boils at 125-126 (12 mm.) (A. 254, 156; B. 23, 3757). d- Chlorsuccinic Acid melts with decomposition at 176. It is obtained from 1-malic acid by means of PC1 5 and water. Its silver salt becomes d-malic acid when it is boiled with water. The dimethyl ester boils at 107 (15 mm.) ; the chloride at 92 (II mm.); the anhydride at 138 (20 mm.) (B. 28, 1289). \-Chlorsuccinic Acid is prepared from 1-aspartic acid, which can be changed to 1-malic acid. Starting, therefore, with 1-aspartic acid, it is not only possible to pre- pare 1-chlorsuccinic acid and 1-malic acid, but with the aid of the latter we can obtain d-chlorsuccinic acid, which can be transposed into d-malic acid (p. 68) : 5*1 1-Chlorsuccinic Acid - d- Chlorsuccinic Acid. Inactive bromsuccinic acid, CO 2 H . CHBr . CH 2 . CO 2 H, from hydrobromic acid and fumaric acid, melts at 160. Its dimethyl ester boils at 110 (10 mm.). Its anhydride melts at 30-31 and boils at 137 (il mm.). ^.-Bromsuccinic Dimethyl Ester, from 1-malic acid and PBr 5 , boils at 124 (20 mm. ) (B. 28, 1291). \-Bromsuccinic Acid, from 1-aspartic acid (B. 28,2770; 29, 1699), melts with decomposition at 173. ISODIBROM-SUCCIN1C ACID. 45 I The free, inactive acids and their esters, when heated at the ordinary pressure, break down into an halogen hydride and fumaric acid and its ester, while the anhy- drides yield the halogen hydride and maleic anhydride (A. 254, 157). Moist silver oxide converts bromsuccinic acid into inactive malic add (see this), which can thus be synthesized in this way. The addition of an haloid acid to ita-, citra-, and mesaconic acids produces chlor- pyrotartaric acids, C 5 H-C1O 4 : (1) Itachlorpyrotartaric Acid, melting at 140-141 (compare paraconic acid, see this, and itamalic acid). (2) Mesa- or Chlorpyrotartaric Acid, melting at 129 (A. 188, 51). Brompyrotartaric Acids, C 5 H 2 BrO 4 : (1) Itabrompyrotartaric Acid, melting at 137. (2) Citrabrompyrotartaric Acid, melting at 148. Dihalogen Substitution Products are produced (l) by the direct action of bromine and water upon the acids ; (2) by the addition of halogen hydride to the monohalogen unsaturated acids of \^ fumaric and maleic series ; (3) by the addition of halogens particularly bromine to the unsaturated acids of the fumaric and maleic series. When hydrobromic acid is added to fumaric and maleic acids they yield the same monobromsuccinic acid, but with bromine, fumaric acid forms the sparingly soluble dibromsuccinic acid, while maleic acid and bromine yield the easily soluble isodibrom- succinic acid and fumaric acid. These two dibromsuccinic acids have the same structural formula, they are symmetrically constructed, and their isomerism is prob- ably due to the same cause prevailing with the s-dialkylic succinic acids (p. 444). Yet they are intimately related to racemic and mesotartaric acids, which were first synthetically prepared by means of the dibromsuccinic acids. Inasmuch as fumaric acid yields racemic acid when oxidized, therefore the sparingly soluble dibromsuccinic acid, the dibrom addition product of fumaric acid, should correspond to racemic acid, and isodibromsuccinic acid to meso-tartaric acid. However, the transposition reac- tions of the dibromsuccinic acids show many contradictions. Dichlorsuccinic Acid, from fumaric acid and liquid chlorine, melts at 215 with decomposition. The methyl ester melts at 32 (A. 280, 210). Isodichlorsuccinic Acid melts with decomposition at 170. It is obtained from the anhydride, melting at 95, the addition product of maleic anhydride and liquid chlorine. When heated, the 'anhydride changes to chlonnaleic anhydride (A. 280, 216). Dibrom-succinic Acid, C 2 H 2 Br 2 (CO 2 H) 2 , consists of prisms which are not very soluble in cold water. When heated to 200-235 it breaks up into HBr and brom- malelc acid, and with acetic anhydride it yields brom-maleic anhydride and acetyl bromide. The methyl ester melts at 62 ; the ethyl ester at 68. Isodibrom-succinic Acid, C 2 H 2 Br 2 (CO 2 H) 2 , is very soluble in water. It melts at 160 and decomposes at 180 into HBr and brom-fumaric acid (p. 464). Its anhydride, C 2 H 2 Br 2 (CO) 2 O, from maleic anhydride and bromine, melts at 42. At 100 it breaks down into HBr and brom-maleic anhydride (A. 280, 207). The anilic acid melts at 144. The anil melts at 177 (A. 292, 233 ; 239, 143). When reduced, both acids yield ethylene succinic acid ; when boiled with potassium iodide they change to fumaric acid, while boiling sodium hydroxide or baryta water converts them into acetylene dicarboxylic acid (A. 272, 127). The sparingly soluble dibrom acid, when boiled with water, passes into brom-maleic acid, while the readily soluble acid, under like treatment, becomes brom-fumaric acid. Two hun- dred parts of boiling water convert the difficultly soluble dibrom-acid, in the pres- ence of the brominated unsaturated acid, into mesotartaric acid, together with a little racemic acid, while the readily soluble acid yields much racemic acid and but little of the mesotartaric acid (A. 292, 295) The silver salt of the difficultly soluble dibrom-acid changes on boiling with water to mesotartaric acid (see this), while racemic acid is obtained under similar condi- tions from the easily soluble isodibromsuccinic acid (B. 21, 268). Much mesotar- taric acid with but little racemic acid is formed on boiling the barium or calcium salt 45 2 ORGANIC CHEMISTRY. of the difficultly soluble dibrom-succinic acid. The contradictions in these reac- tions are made clearer in the scheme which follows : KMnOj Fumaric Acid > Racemic Acid TVTalAir Arirl ?- mesoiananc .tt-ciu KMnC-4 1 Isodibromsuccinic Acid ?> Racemic Acid. Trichlor succinic Acid is a crystalline, exceedingly soluble mass, obtained on expos- ing chlormaleic acid, water and liquid chlorine to sunlight (A. 280, 230). Tetrachlorsuccinanil, melting at 157, is formed together with dichlormale'inanil chloride (p. 464), when PC1 5 acts upon dichlormale'inanil (A. 295, 33). Tribrom-succinic Acid, C 2 HBr 3 (CO 2 H) 2 , is produced when bromine (and water) acts upon brom-maleic acid and isobrom-malei'c acid ; it consists of acicular crystals, which melt at 136-137. The aqueous solution decomposes at 60 into CO 2 , HBr, and dibromacrylic acid, C 3 H 2 Br 2 O 2 , which melts at 85. Dibrompyrotartaric Acids. The addition of bromine to ita-, citra- and mesaconic acids gives rise to three dibrompyrotartaric acids, which upon reduction revert to the same pyrotartaric acid (p. 444) . The ita-, citra- and mesa-dibrompyrotartaric acids, C 5 H 6 Br 2 O 4 , are distin- guished by their different solubility in water. The ita- compound changes to aconic acid, C 5 H 4 O 4 , when the solution of its sodium salt is boiled ; the citra- and mesa- compounds, on the other hand, yield brom-methacrylic acid (p. 283). An excess of caustic potash will convert citradibrompyrotartaric acid into brom- mesaconic acid (p. 464). GLUTARIC ACID GROUP. Glutaric acid and its alkylic derivatives, like ethylene succinic acid, are characterized by the fact that when they are heated they break down into anhydride and water. The anhydrides readily yield anilic acids, from which anils can be obtained by the with- drawal of water. The glutaric acids resemble the ethylene succinic acids in deportment, but they are changed to anhydrides with greater difficulty by acetyl chloride, and are not so volatile with steam. /-"FT ff) IT Glutaric Acid, CH 2 < C pj 2 . CO 2 H' Normal Pyrotartaric Acid \_Pent- an diacid~\i is isomeric with monomethyl succinic acid or ordinary pyrotartaric acid, as well as with ethyl and dimethylmalonic acids (P- 437)- It was first obtained by the reduction of a-oxyglutaric acid with hydriodic acid. It may be synthetically prepared from tri- methylene bromide (p. 303), through the cyanide ; from acetoacetic ester by means of the aceto-glutaric ester (see this) ; from glutaconic acid (p. 467), and from propane tetracarboxylic acid or methylene dimalonic acid, C 3 H 4 (CO 2 H) 4 , by the removal of 2CO 2 . Glutaric acid crystallizes in large monoclinic plates, melts at 97, and distils ALKYL-GLUTARIC ACIDS. 453 near 303, with scarcely any decomposition. It is soluble in 1.2 parts water at 14. The calcium salt, C 5 H 6 O 4 Ca + 4H 2 O, and barium salt, C 5 H 6 O 4 Ba + 5_H 2 O (like calcium butyrate, p. 247), are easily soluble in water; the first more readily in cold than in warm water. The mo nomethyl ester boils at 153 (20 mm.) (B. 26, R. 276). The ethyl ester boils at 237. The anhydride, C 5 H 6 O 3 , forms on slowly heating the acid to 230-280, and in the action of acetyl chloride on the silver salt of the acid. It crystallizes in needles, melting at 56-57. Glutarimidc, C 3 H 6 (CO) 2 NH, results by the distillation of ammo- nium glutarate and by the oxidation of pentamethylene imide (p. 315), or piperidine with H 2 O 2 (B. 24, 2777). It yields a little pyridine when it is heated with zinc dust (B. 16, 1683). It melts at 152. CH CN Nitrile of Glutaric Acid, Trimethylene Cyanide, CH 2 C > CH A /^ /\ H S CCH 3 H 3 C CH 2 CH 3 CH 2 Br C0 2 C 2 H 5 C0 2 C 2 H 5 C0 2 C 2 H 5 CO 2 C 2 H 5 CH CH 2 Br '+ 2Ag -f CBr =CH CH 2 C + 2AgBr. /\ /\ CH 3 CH 3 CH 3 CH 3 CH 3 CH, In the second stage sodium methyl malonic ester attaches itself to methyl acrylic 454 ORGANIC CHEMISTRY. ester, and when the addition product is saponified it yields dimethyl glutaric acid (B. 24, 1041, 1923): C0 2 C 2 H 5 C0 2 C 2 H 5 C0 2 C 2 H 5 CO 2 C 2 H 5 C= =CH 2 -f NaC-C0 2 C 2 H 5 = CNa-CH 2 C CO 2 C 2 H 5 CH 3 CH 3 CH 3 CH 3 aa^-Dlmethyl Glutaric Acids, CH 2 [CH(CH 3 )CO 2 H] 2 , melting at 127 and 140 (A. 292, 146; B. 29, R. 421), also result from the action of methylene iodide upon sodium a-cyanpropionic ester. Bromine converts both acids into a brom-products, from which oxydimethyl glutaric acids and their lactones are obtained (B. 25, 3221; A. 292, 146). aa^-Diethyl Glutaric Acids (A. 292, 204). afi-Dimethyl Glutaric Acid (A. 292, 147 ; B. 29, 2058). Unsym. aa^-Dimethyl Glutaric Acid, CO 2 H . C(CH 3 ) 2 . CH 2 . CH 2 . CO 2 H, melts at 85, and its anhydride at 38. ^-Dimethyl Glutaric Acid, CO 2 H . CH 2 C(CH 3 ) 2 - CH 2 CO 2 H, from dimethyl acrylic ester with sodium or potassium malonic ester, and subsequent decomposition of the dimethyl propane tricarboxylic acid (A. 292, 145 ; C. 1897, I, 28), melts at 100, and its anhydride at 124. The anilic acid melts at 134. a, a, a^-Trimethyl Glutaric Acid, CO 2 H . CH(CH 3 )CH 2 C(CH 3 ) 2 . CO 2 H, melts at 97 (compare tetramethyl succinic acid). Its anhydride melts at 96 and boils at 262 (A. 292, 220). GROUP OF ADIPIC ACID AND HIGHER NORMAL PARAFFIN DICAR- BOXYLIC ACIDS. Adipic acid and its alkylic derivatives volatilize under reduced pressure without decomposition. They, together with normal pimelic acid and suberic acid, are characterized by the fact that when their calcium salts are heated cyclic ketones result (J. Wislicenus, A. 275, 309): CH 2 . CH 2 . C0 2 H .CH 2 . CH 2 . CO 2 H . CH 2 . C0 2 H Adipic Acid 2 \CH 2 .CH 2 .C0 2 H Normal Pimelic Acid ' 2 \ co J._ /CH 2 .CH 5 [ 2 . CH 2 . CH 2 C0 2 H Suberic Ac EL x co CH 2 .CH 2 .CH 2 X Oxo- or Ketopenta- Oxo- or Ketohexamethylene Suberone methylene [Cyclohexauon] [Cycloheptanon]. [Cyclopentanon] When adipic acid and the higher saturated dicarboxylic acids are boiled with acetyl chloride, anhydrides are also produced. It is not known whether they should receive the simple molecular formula'or a multiple of it (B. 27, R. 405 ; C. 1896, II, 1091). Adipic Acid [Hexan diacid], CO 2 H[CH 2 ] 4 CO 2 H, was first obtained by oxidizing fats with nitric acid. It is also produced (l) in the reduction of hydromucomc acid (p. 467). It is synthetically prepared (2) by heating /5-iodpropionic acid, with reduced silver, to 130-140, or with copper to 160 (B. 28, R. 466) ; (3) by the electrolysis of potassium ethyl succinic ester (A. 261, 117), and (4) from ethylene dimalonic acid or butane tetracarboxylic acid. Sodium converts adipic ester into /?-ketopentamethylene monocarboxylic ester (B. 27, 103). Cyclopentanon is pro- duced when the calcium salt is distilled. PIMELIC ACID. 455 a- Methyl Adipic Acid melts at 64. a-Ethyl Adipic Acid is a liquid, fi- Methyl Adipic Acid melts at 89 and boils at 210-212 (14.5 mm.). It results from the oxi- dation of pulegone and menthone (A. 292, 148). aa^Diethyl Adipic Acids have been prepared from the corresponding aaj-dialkylic ethylene dimalonic acids, aa^- Dim ethyl Adipic Acid (see B. 27, 1578). aa^Diethyl Adipic Acids (see B. 28, R. 300). a-Bromadipic Acid melts at 131 (B. 28, R. 466). Normal Pimelic Acid [Heptan diacid], CH 2 <2 H 2 . CO 2 H (A 2Q2j 150), first prepared by oxidizing suberone, and from salicylic acid through the action of sodium in amyl alcohol solution (A. 286, 259) ; by heating furonic acid, C 7 H 8 O 5 , with HI, and in the oxidation of fats with nitric acid, can be obtained synthetically from trimethylene bromide and malonic ester by heating pentamethylene tetracar- boxylic acid, which is the first product of the reaction (B. 26, 709). It melts at 105. When its lime salt is distilled [cyclohexanon] is produced (p. 454)- Alkylic Pimelic Acids : -, /:?-, and y-Methyl Pimelic Acids melt at 54, 49, and 56. They are formed when the o-, m-, and p-cresotic acids, or better their dibrom-derivatives, are reduced by amyl alcohol and sodium (A. 295, 173). The a-acid may also be prepared from the corresponding tetracarboxylic acid (B. 29, 729). aa^-Dimethvl Pimelic Acids melt at 8l and 76 (B. 28, R. 465). afid-Trimethvl Pimelic Acid boils at 214 (15 mm.) (B. 28, 2943). aa v Dib>ompimelic Acid melts at 141. Its diethyl ester, boiling at 224 (28 mm.), when acted upon .by sodium ethylate becomes A / -cyclopentene-dicarboxylic acid. Suberic Acid [Octan diacid], C 8 H U O 4 , is obtained by boiling corks (B. 26, 3089), or fatty oils, with nitric acid (B. 26, R. 814). It melts at 140. Its ethyl ester boils at 280-282. It has been synthesized by electrolyzing potassium ethyl glutarate. Suberone (p. 454) results when its calcium salt is distilled (A. 275, 356). Its anhy- dride melts at 62. The dihydrazide melts at 185. The diazide melts at 25 (B. 29, Il66). See also I.6-hexamethylene diamine, p. 313. Higher dibasic acids are produced by oxidizing the fatty acids or oleic acids with nitric acid. They always form succinic and oxalic acids at the same time. The higher acetylene carboxylic acids usually decompose into the acids C n H 2n O 4 , when oxidi/ed with fuming nitric acid. The mixture of acids that results is separated by fractional crystallization from ether; the higher members, being less soluble, separate out first (B. 14, 560). Such acids have also been produced by the breaking- down of ketoximic acids through the action of concentrated sulphuric acid, e. g. , sebacic acid from ketoxime stearic acid. See p. 285 for the importance of this reaction. Lepargylic Acid, C 9 H 16 O 4 , Azelaic Acid [Nonan diacid], is best prepared by oxidizing castor oil (B. 17, 2214). It melts at 106. It can be synthesized from pentamethylene bromide and sodium acetoacetic ester (B. 26, 2249). Its anhydride melts at 52. Sebacic Acid, C ]0 H 18 O 4 [Decan diacid], is obtained by the dry distillation of oleic acid, by the oxidation of stearic acid and spermaceti, from ketoxime stearic acid, and from heptane tetracarboxylic acid (B. 27, R. 413). The acid melts at 133. The anhydride melts at 78. Brassylic Acid, C U H 20 O 4 , obtained by oxidizing behenoleic and erucic acids, melts at 114 (B. 26, 639, R. 795, 811). Roccellic Acid, C 17 H 32 O 4 , occurs free in Rocdla tinctoria. It melts at 132. 45 6 ORGANIC CHEMISTRY. B. OLEFINE DICARBOXYLIC ACIDS, C n H 2n _ 4 O 4 . The acids of this series bear the same relation to those of the oxalic acid series that the acids of the acrylic series bear to the fatty acids. The free acid hydrates of all the acids of the oxalic series are known, but in the case of the unsaturated acids there are some, like carbonic acid, which only exist in the anhydride condition. When the attempt is made to liberate the acids from their salts, they imme- diately split off water and pass into the corresponding anhydrides, e. g., dimethyl and diethyl-malei'c anhydrides. The analogy of such acids with carbonic acid, to which reference has already been made (p. 290), manifests itself in the following constitutional formulas (A. 254, 169; 259, 137): s s-\*fr \. ^ O=C= O + H 2 O ON* CH 3 . C_C/10Na / / OH \ /CH 3 .C_C40H \ CH 3 . < il ) CH 3 . C_C=0 la, !c>S r \ CH 3 . C C=O / CH 3 .( Pyrocinchonate or Dimethyl maleate of Sodium Pyrocinchonic Acid (Does not exist) Pyrocin hyc Hence, dimethyl and diethyl-malei'c acids cannot contain two carboxyl groups any more than carbonic acid can contain them. Even in the salts and esters a ^-lactone ring would be present. The hypothetical acid hydrates would be unsaturated ^-dioxy-lactones. The cycloparaffin dicarboxylic acids, having a like carbon content and isomeric with the unsaturated dicarboxylic acids, will be discussed after the cycloparaffins, e. g. : CH Trimethylene Dicarboxylic Acid, \ 2 >C(CO. 2 H) 2 CH 2 . CH.C0 2 H Tetramethylene Dicarboxyhc Acid, \ \ CH CH . COH Pentametkylene Dicarboxylic Acid, . 2 2 ' 2 CH The lowest member of the series has two possible structural iso- merides : methyUne malonic acid, CH 2 : C(CO 2 H) 2 , and ethylene dicar- boxylic acid, CO 2 HCH : CH . CO 2 H. The first is only known in the form of its ester. However, there are two acids, fumaric and male'ic acids, which it is customary to regard as different modifications of ethylene dicarboxylic acid. (a) Alkylen Malonic Acids. Methylene Malonic Ester, CH 2 : C consists of prismatic crystals, which effloresce and when boiled with water change to C 4 H 2 O 4 Ba a salt that is practically insoluble in water. The esters are obtained from the silver salt by the action of alkyl iodides, and by leading HC1 into the alcoholic solutions of fumaric and maleic acids (B. 12, 228}). They are also produced in the distillation of the esters of brom-succinic acid, malic acid and aceto-malic acid (B. 22, R. 813). They are also obtained from maleic esters (see p. 459), and from diazoacetic esters on the application of heat (B. 29, 763). They unite 2Br, forming esters of dibromsuccinic acid. The methyl ester, C 2 H 2 (CO 2 . CH 3 ) 2 , melts at 102, and boils at 192. The ethyl ester is liquid, and boils at 218 (B. 12, 2283). Many other substances have the power of adding themselves to them, e.g., sodium acetoacetic ester, sodium malonic ester (B. 24, 309, 2887, R. 636), sodium cyan- acetic ester (B. 25, R. 579), diazoacetic ester (p. 365) phenyl azoimide, etc. Fumaryl Chloride, COC1 . CH : CH . CO . Cl, boiling at 160, is produced when PC1 5 acts upon fumaric acid (B. 18, 1947). Bromine converts it into dibromsuccinyl chloride (A. Suppl. 2, 86), and with sodium peroxide (hydrate) it yields Fumaric Peroxide, C 4 H 2 O 4 , a white powder, exploding at 80 (B. 29, 1726). Fumaramic Acid, CONH 2 . CH : CH . CO 2 H, melts at 217. It is formed when asparagine is acted upon with methyl iodide and caustic potash (A. 259, 137). Fumaramide, CONH^CH = CH . CONH 2 , melts at 266 (B. 25, 643). Fumarhydrazide, NH 2 . NH . CO . CH : CH . CO . NH . NH 2 , melts with de- coinposii ion at 220. Fumarazide is crystalline. It explodes easily, and when boiled with alcohol yields Fumarethyl urethane (B. 29, R. 231). MALEl'C ANHYDRIDE. 459 Fumaranilic Acid, CONHC 6 H 5 CH = CH.CO 2 H, from the corresponding chloride and water, melts at 230-231. Fumaranilic Chloride, CONH . C 6 H 5 . CH = CH . COC1, melting at 119-120, crystallizes from ether in transparent, strongly refracting, sulphur-yellow colored prismatic needles or plates. It is produced when aniline acts upon fumaryl chloride in excess. Fumardianilide , CONHC 6 H 5 CH = CHCONHC 6 H 5 (A. 239, 144). Malei'c Acid, C 4 H 4 O 4 , melting at 130, boils at 160 with decom- position into malei'c anhydride and water. Its anhydride is formed as mentioned under fu marie acid : (1) By the rapid heating of malic acid. (2) In the slow distillation of monochlor- and monobromsuccinic acid, as well as acetyl malic anhydride at the ordinary pressure. (3) By the action of PC1 5 upon malic acid (A. 280, 216). (4) Malei'c acid is formed synthetically, in small amount, when silver or sodium acts upon dichloracetic acid and dichloracetic ester. (5) Malei'c acid is obtained on decomposing trichlorphenomalic acid or /3-trichloracetoacrylic acid (p. 382) with baryta water. Chloroform is produced at the same time. (6) From .fu marie acid (see transformations of fumaric and male'ic acids). Male'ic acid crystallizes in large prisms or plates, is very easily soluble in cold water, and possesses a peculiar, disagreeable taste. Salts. QH 2 O 4 Ag 2 is a finely divided precipitate. It gradually changes to large crystals. C 4 H 2 O 4 Ba -}- laq is soluble in hot water, and crystallizes well. The esters result from the action of alkyl iodides upon the silver salt: The methyl ester, C 2 H 2 (CO 2 . CH 3 ) 2 , is a liquid, and boils at 205. The ethyl ester boils at 225. When heated with iodine they change for the most par into fumaric esters. Malei'c Anhydride, 11 >O, melting at 53 and boiling at 202, CHCO is produced (i) by distilling male'ic or fumaric acid alone, or more readily (2) with acetyl chloride; (3) by the distillation of mono- chlor- and monobromsuccinic acids, and also of aceto-malic an- hydride (A. 254, 155); (4) when PC1 5 , P 2 O 5 and POC1 3 act upon fumaric acid (A. 268, 255). It is purified by crystallization from chloroform (B. 12, 2281 ; 14, 2546). It consists of needles or prisms, having a faintly penetrating odor. It regenerates male'ic acid by union with water, and forms isodibromsuccinic anhydride when heated with bromine. Malelc Chloride (B. 18, 1947). /NH, CH . CONH 2 CH . C^-OH Malelnamic Acid, || or II /O (?), melts at 152-1 O , melting at III , is obtained from maleic CH . CO anhydride and hydrazine hydrate in alcohol. When its solution is heated it changes CH . CO . NH to Malelnhydrazide, I I , consisting of little, white crystals, which do not v-/ Ji * CvV-/ JN L melt at 250. It is a strong acid. BEHAVIOR OF FUMARIC AND MALEIC ACIDS. 1. Acetylene is formed when the alkali salts of these acids are electrolyzed (p. 96). 2. Sodium amalgam, or zinc, reduces them both to succinic acid. 3. When heated to 100 with caustic soda both acids change to inactive malic acid (A. 269, 76). 4. Fumaric and maleic esters react with sodium alcoholates to form alkylic oxy- succinic acids (B. 18, R. 536). 5. Bromine converts : Fumaric acid into dibromsuccinic acid. Fumaric ester " " " ester. Fumaryl chloride " " succinyl chloride. Maleic anhydride " isodibromsuccinic anhydride. 6. Potassium permanganate changes (B. 14, 713) : Fumaric acid into racemic acid. Maleic " " mesotartaric acid. CONVERSION OF FUMARIC AND MALEIC ACIDS INTO EACH OTHER. 1. When fumaric acid is heated, or treated with PG 5 , POC1 3 and P 2 O 5 (A. 268, 2 55 > 2 73> 3 1 ) it becomes maleic anhydride. 2. Maleic acid changes to fumaric acid : (a) When it is heated alone in a sealed tube to 200 (B. 27, 1365). () By the action of cold HC1, HBr, HI and other acids ; SO 2 and H 2 S (B. 24, R. 823), as well as by the action of bromine in sunlight (B. 29, R. 1 080). (c) On heating maleic ester with iodine fumaric esters result. (d) Alcoholic potash changes maleinamic and maleinanilic acids to fumaric acid. FUMARIC AND MALEIC ACIDS. 461 THE ISOMERISM OF FUMARIC AND MALEIC ACIDS. The view generally accepted as to the cause of the isomerism of these two acids was presented in the introduction, under the section relating to the geometrical isomerism, the stereoisomerism of the ethylene derivatives (p. 49). In conformity with this representation we find in maleic acid, readily forming an anhydride, an atomic grouping, which follows the plane-symmetric configuration, according to which the carboxyl groups are so closely arranged with reference to each other that the production of an anhydride follows without difficulty. Fumaric acid is not capable of forming an anhydride, hence it has the central or axial symmetric structure. These space-formulas satisfactorily represent the intimate connection existing, as shown by Kekule and Anschiitz, between fumaric and racemic acids, and maleic and inactive tartaric acids. According to the van t'Hoff-Le Bel view of these four acids, the oxidation of fumaric to racemic acid by means of potassium permanganate and maleic to mesotartaric acid, may be shown by the following formulas, which have a spacial significance (compare p. 49) : C0 2 H C0 2 H H C-C0 2 H H *C-OH HO *C-H 2. -f 20 + 2H 2 = | + | CO 2 H C H HO *C H H *C OH CO,H CO,H Fumaric Acid Dextro-tartaric Acid + Lsevo-tartaric Acid = Racemic Acid. CO 2 H H C CO 2 H H *C OH + O + H 2 = , j H C CO,H H *C-OH CO 2 H Maleic Acid Mesotartaric Acid. The oxidation of the two acids, based on stereochemical formulas, is so represented that upon severing the double linkage in fumaric acid by the addition of hydroxyl groups an equal number of mole- cules of dextro- and laevo-tartaric acid results, while by the rupture of the double linkage in maleic acid only mesotartaric acid is formed. Cognizant of this view, J. Wislicenus has sought to explain the conversion of maleic into fumaric acid by hydrochloric acid in the following manner : In these two acids the two doubly-linked carbon atoms cannot rotate independently of each other, consequently not in opposite directions, but when the double union is removed by the addition of two univalent atoms, then free rotation is restored. Accordingly, J. Wislicenus explains the conversion of maleic acid by means of hydrochloric acid into fumaric acid as follows: Considering the extreme ease with which maleic acid, in contrast to furaaric acid, lends itself to the formation of addition products (B. 12, 2282), it first absorbs the elements of the mineral acids (- I =^> II C H C C0 2 H H H H C0 2 H Malei'c Acid Monochlorsuccinic Acid Fumaric Acid. previous to after rotation rotation in the preferred position However, the intermediate product, monochlorsuccinic acid, is known in the free condition, that is, in the preferred configuration. It is stable toward hydrochloric acid at IO, and its anhydride unites with water to the original acid, instead of yield- ing fumaric acid, although in so doing the monochlorsuccinic acid, as predicted by J. Wislicenus, in the conversion of maleic into fumaric acid would change, through rotation, from the less favorable to the preferred configuration (Anschiitz, A. 254, 168). This is by no means the only fact with which the preceding explanation of the mechanism of the reactions showing the conversion of fumaric into maleic acid, and vice versa, clashes (compare B. 20, 3306; 24, R. 822; 24, 3620; 25, R. 418; 26, R. 177; A. 259, I ; 280, 226). In the introduction to the unsaturated dicarboxylic acids it was shown that at least some of these acids could only exist in the anhydride form, as their hydrate forms broke down in the moment of their liberation from salts into anhydrides and water. These acids are intimately related to maleic acid ; they are the dialkylic maleic acids. The monoalkylic acids are still capable of existing in hydrate form, although they change more easily than maleic acid to their anhydrides. Considering the analogy with carbonic acid, the salts of the dialkylic maleic acids may be viewed as derivatives of a hypothetical acid hydrate, in which the two hydroxyl groups are attached to the same carbon atom, and this view may be considered to prevail with maleic acid and with the monoalkylic maleic acids, so similar to the dialkylic maleic acids. The assumption that fumaric acid is symmetrical ethylene dicarboxylic acid and maleic acid the y-dioxylactone corresponding to this dicarboxylic acid in no wise renders a stereochemical formulation of the two acids impossible. Probably the stereochemical, different arrangemj|prt"and the different position, in the cherfiical struc- ture, of the atoms contained in both acids mutually influence each other (A. 254, 168): OH H . C . COOH H . C . C OH II II >0 C0 2 H.C.H H.C.CO Fumaric Acid Maleic Acid. However, even this view, as yet, does not afford a satisfactory explanation of the reactions by which these acids are converted into each other. Consult A. 239, 161, for the history of the isomerism of fumaric and maleic acids. The various ideas as to the cause of the isomerism of fumaric and maleic acids are connected with the question as to the nature of the double linkage (p. 51). Finally, attention may be directed to the difference in the heat of combustion of the acids. This would indicate that the energy present in the acids, in the form of atomic motion, is markedly different. "This fact suggests the possibility that the HALOID FUMARIC AND MALEIC ACID. 463 cause of the isomerisra is not to be sought exclusively in the varying arrangement of the atoms, nor in their different spacial positions, but that we should also consider the varying magnitude of the motion of the atoms (or atom complexes)." It is also pos- sible to imagine a case in which the isomerism would only be influenced by the differ- ence in energy content a case in which there might be perfect similarity in linkage and also in the spacial arrangement of the atoms." In addition to structural and spacial isomerism, we would have the hypothesis of an energy or dynamical isomerism (Tanatar, A. 273, 54; B. II, 1027; 29, 1300), which would vastly more deserve this name than the views to which attention has been drawn in connection with the sym. dialkylic succinic acids (p. 444). It is by no means established that fumaric acid is not a polymeric modification of maleic acid. That their vapor densities are the same proves nothing on this point, inasmuch as the vapor densities of racemic and tartaric esters are identical, and yet the molecule of solid racemic acid consists of a molecule each of dextro- and la^votartaric acid. The same remarks are true in regard to the results obtained by the freezing-point depressions. HALOID FUMARIC AND MALEIC ACIDS. Monochlorfumaric Acid, C 4 H 3 C1O 4 , melting at 192, results (i) from tartaric acid and PC1 5 or PC1 3 ; (2) from the two dichlorsuccinic acids ; (3) from acetylene dicarboxylic acid and fuming nitric acid. Mono- chlonnaleic Acid melts at 106 ; its anhydride melts at o and 34, and boils at 197 (760 mm.), 95 (25 mm.). It is produced when acetyl chloride acts upon chlorfumaric acid, and when isodichlorsuccinic anhydride is heated (A. 280, 222). Brom-malei'c Acid, C 4 H 3 BrO 4 , is produced by boiling dibromsuccinic acid with water. It melts at 128. Its anhydride, boiling at 215, results when isodibrom- succinic anhydride is heated alone, or by the action of acetic anhydride on dibrom- succinic acid. HBr converts it into dibromsuccinic acid and bromfumaric acid. Brom-fumaric Acid, C 4 H 3 BrO 4 , is formed by boiling isodibromsuccinic acid, or by the addition of HBr to acetylene dicarboxylic acid. It melts at 179. When heated alone, or upon boiling with acetyl chloride, both acids yield brom- maleic anhydride. Mono-iodo-fumaric Acid melts at 182-184 (B. 15, 2697). Dichlormaleu Acid, C 4 C1 2 H 2 O 4 , results when hexachlor-p-diketo-R-hexene, CO C0 ' and perchloracetylacrylic acid, CC1 3 CO. CC1 = CC1 . CO 2 H (p. 382), are decomposed by caustic soda (A. 267, 20 ; B. 25, 2230). On the applica- tion of heat it passes into the anhydride, C 2 C1 2 (CO) 2 O, melting at 120. PC1 5 con- verts succinic chloride into two isomeric dichlormaleic chlorides (B. 18, R. 184). CC1 . CO Its imide, \\ >NH, is obtained when succinimide is heated in a cur- CC1 . CO rent of chlorine. It melts at 179. One molecule of PC1 5 changes the imide to CC1 CC1 2 dichlormaleln imide-chloride, 1 1 >NH, melting at 147-148 ; this combines CC1-CO CC1 . C = N . C 6 H 5 with aniline to dichlormaleln imide-anil, \\ >NH , melting at 151-152. CC1 . CO Two molecules of PC1 5 convert dichlormaleln- imide into pentachlorpyrrol, C 4 C1 5 N, boiling at 90.5 (10 mm.). Dichlormaleln-anil, melting at 203, is produced when dichlormaleln anil chloride is boiled with glacial acetic acid or water. 464 ORGANIC CHEMISTRY. Dichlormalein anil chloride, melting at 123-124, boiling at 179 (u mm.) is CC1 = CC1 produced, together with tetrachlor-v-phenyl pyrrol, I _>N . C 6 H 5 , melting at 93, on treating succinanil with PC1 5 . By reduction it yields d-anilido butyric- lactam (see succinimide, p. 448). Alcohols convert it into dialkylic esters: dichlor- maleln- anil- dimethyl ester, melting at no ; while with aniline it yields dichlor- malemdianil, melting at 186-187 (A. 295, 27) : CH 2 .CO 4 p C l 6 CC1.CC1, IO H CH 2 -CH 2 | >N.C 6 H 6 - > || >NC 6 H 5 -- ->J >N.C 6 H 5 CH . CO CC1 . CO \ CH CO v,j.j. 2 . \^\j Succinanil .L *|- Trri rri Y CH 2 CO Dichlormaleinanil >^ y-Anilidobutyric Chloride \ Lactam CC1=CC1 T CC1 . C(OCH 3 ) 2 CC1 . C=NC 6 H 5 I >N.C 6 H 5 || >N.C 6 H 5 || >NC 6 H 5 CC1=CC1 CC1 . CO CC1 . CO n-Phenyltetrachlorpyrrol Dichlormalei'nanil Dichlormalei'ndianil. Dimethyl Ester Dibrom-maleic Acid, C 2 Br 2 (CO 2 H) 2 ,is obtained by acting on succinic acid with Br, or by the oxidation of mucobromic acid with bromine water, silver oxide or nitric acid. It is very readily soluble, melts at 120 125, and readily forms the anhydride, C 2 Br 2 (CO) 2 O, which melts at 115 (B. 13, 736). Chlorbrom-malelc Acid, see B. 29, R. 186. Dibrom-fumaric Acid, melting at 219-222, and Di-iodofumaric acid, decomposing at 192, are the additive products of bromine and iodine with acetylene dicarboxylic acid (B. 12, 2213; 24, 4118). Acids, C 5 H 6 O 4 = C 3 H 4 (CO 2 H) 2 . Eight dicarboxylic acids, having this formula, are known. There are four unsaturated acids isomeric with ethidene malonic acid described on p. 457 : (i) Mesaconic acid, (2) Citraconic acid, (3) Itaconic acid, (4) Glutaconic acid, and three trimelhylene dicarboxylic acids. Mesaconic and citraconic acids bear the same relation to each other as fumaric to male'ic acid. They show similar conversions of one into the other. These, however, occur less readily than in the case of the latter acids (B. 29, R. 412). The in- troduction of the methyl group increases the tendency of citraconic acid very considerably to break down into its anhydride and water. This takes place at 100 under diminished pressure (compare chloral hydrate). Mesaconic acid is more easily changed by acetyl chloride to citraconic anhydride than fumaric acid to male'ic anhydride. Furthermore, maleic anhydride combines more readily, and therefore more rapidly, with water than citraconic anhydride. (1) Mesaconic Acid, Methyl Fumiric Acid, Oxytetrinic Acid, C 3 H 4 (CO 2 H) 2 , is prepared by heating citra- and itaconic acid with a little water to 200 and by evapo- rating citraconic acid with dilute nitric acid, cone, haloid acids, or with concentrated sodium hydrate (B. 269, 82; B. 29, 412) (Compare a- and /?-methyl malic acid (p. 492) and from dibrommethyl acetoacetic acid (p. 378), Brommesaconic Acid melts at 220 (B. 27, 1851, 2130). It dissolves with difficulty in water and melts at 202. (2) Citraconic Acid, methyl maleic acid, melting at 80 and easily soluble in water, is obtained from its anhydride by heating the latter with water. Citraconic Anhy- CH 3 . CCO dride, || ^O, melting at 7 and boiling at 213-214, is also formed by heat- HCCO HOMOLOGUES OF MESA-, CITRA- AND ITACONIC ACIDS. 465 ing the acid and mesaconic acid, or on treating them with acetyl chloride, and is obtained by the repeated distillation of the distillate resulting from citric acid, due, probably, to a rearrangement of the itaconic anhydride produced at first. When boiled with a return condenser, it is changed in part to xeronic acid or di- ethylmaleic anhydride, p. 466. Bromcitraconic Anhydride melts at 99 (B. 27, 1855). Hydrogen converts citra- and mesaconic acids into pyrotartaric acid (p. 444). Their haloid acid and halogen addition products have been described_as halogen sub- stitution products of pyrotartaric acid (p. 451). Allylene, CH 3 C = CH, results in the electrolysis of both acids. Citraconanilic Add melts at 153 (A. 254, 135). Citraconanil melts at 98 (B. 23, 2979; 24, 314). y"T_T r* _ C*C\ TT (3) Itaconic Acid, methylene succinic acid, 2 i, , melting at CH 2 CO 2 H 161, is formed by the union of its anhydride with water, or when citraconic anhy- dride is heated with 3-4 parts of water to 150. Hydrogen causes it to revert to pyrotartaric acid, and when electrolyzed yields sym. allylene or allene, CH 2 :=- C = CH 2 (p. 99) . It forms psendoitaconanilic acid, the lactam of >'-anilidopyro- tartaric acid (p. 492) (A. 254, 129), when it is boiled with aniline. For the addition of HBr and Br 2 see p. 451. The itaconic esters readily polymerize to vitreous modifications, having high refractive power (B. 14, 2787 ; A. 248, 203). ^-iTT /"* C*C\ Itaconic Anhydride, i >O, melting at 68 and boiling at 139- CH 2 CO 140 (30 mm.), is probably the first decomposition product of aconitic acid, resulting from heating citric acid. The name aconitic acid gives rise to the name itaconic acid by syllable exchange. It has been obtained from its hydrate (B. 13, 1539), and from the silver salt by the action of acetyl chloride (B. 13, 1844). It has also been de- tected in the products formed in the distillation of citric acid (B. 13, 1542). It crystallizes from chloroform in rhombic prisms, melts at 68, and distils unaltered under diminished pressure, but at ordinary pressures changes to citraconic anhydride. It combines with water more readily than the latter. Itaconanilic Acid melts at 151.5 (A. 254, 140). Homologues of Mesa-, Citra- and Itaconic Acids. Before discussing glutaconic acid, the homologues of mesa-, citra-, and itaconic acids will be presented. The homologues of citraconic acid are produced when alkylic paraconic acids the condensation products resulting from aldehydes and suc- cinic acid, or pyrotartaric acid (p. 492) are heated alone (A. 255, I ; 283, 47). The monoalkylic maleic acids have yielded the homologues of mesaconic acid. HoT.vever, the dialkylic maleic acids onty exist as anhydrides in the free state, but can be converted, by boiling -with concentrated caustic soda, into the corresponding dialkylic fnmaric acids (B. 29, 1842). The conversion of certain itaconic acids into isomeric aticonic acids with caustic alkali is very remarkable. They seem to bear the same relation to each other that has been observed with fu marie and maleic acids. The products of the action of alcoholic potash upon the dibrom-derivatives of the mono- alkylic acetoacetic esters have been recognized as alkyl fumaric acids ; thus, oxytetrinic acid is mesaconic acid, oxypentinic acid is ethyl fumaric acid, etc. (p. 379). Further- more, monoalkylic fumaric acids have been obtained from monoalkylic ethane tricar- boxylic acids by the elimination of halogen hydride and CO 2 after the halogens have been introduced (B. 24, 2008). Mono-alkylic Fnmaric and Maleic Acids : M. P. M. P. B. P. Ethyl Fumaric Acid, 194 ; Ethyl Maleic Acid, 100 ; Anhydride, 229. n-Propyl Fumaric Acid, 174 ; n-Propyl Maleic Acid, 94 ; " 224. Isopropyl Fumaric Acid, 1 86. 466 ORGANIC CHEMISTRY. R'. C . C<\ Dialkylic Maleic Anhydrides : )O. R'. C . CQ / (1) Dimethylmaleic Anhydride, Pyrocinchonic Anhydride, melts at 96 and boils at 223. (2) Methylethylmaleu Anhydride is a liquid boiling at 236-237. (3) Diethylmaleic Anhydride, Xeronic Anhydride, is a liquid boiling at 242. Compounds I and 2 were obtained by heating the condensation product of succinic (or pyrotartaric) acid and pyroracemic acid to 130-140 with acetic anhydride until the evolution of CO 2 ceased (A. 267, 204). Xeronic anhydride results when citra- conic anhydride is heated with a return cooler. The three anhydrides are volatile in steam ; they do not combine with water. Their hydrates cannot exist. They, how- ever, form salts and esters (see p. 456). Dimethyl Maleic Anhydride, or Pyrocinchonic Anhydride, is obtained by oxidizing turpentine oil (together with terebic acid) with nitric acid ; also by heating cinchonic acid : CH 2 . CH (CO 2 H) . CH . CO 2 H CH 3 . C= =C . CH 3 io-o- -iH, io-o_C = c _ co c H i H I ^-"3 I CO CH 2 . CO ? Na Terebic Ester Sodium Teraconethyl Ester. They are also produced when the mono-alkylic citraconic acids are heated to 140- 150 with water (B. 25, R. 161 : A. 256, 99). CH CH _ C _ CO H y-Methylitaconic Acid, Ethidene Succinic Acid, i^ ' , melts at CH 2 . CO 2 H 165-166. a-Methylitaconic Acid melts at 150 (see pyrocinchonic acid). Ethyl- itaconic Acid melts at 164-165. ^-Propylitaconic Acid melts at 159. Isobutylita- conic Acid melts at 160-165. C*f~\ TT Teraconic Acid, y-Dimethylitaconic Acid, (CH~) 2 C : C< r ,TT 2 rnw is P ro ' V^lln \~\}<.^\- duced in small quantity (together with pyroterebic acid) (see this) in the distillation of terebic acid and by the condensation of succinic ester and acetone with sodium ethyl- ate (B. 27, 1122). It melts at 162, decomposing at the same time into water and its anhydride, C 7 H S O 3 . The latter boils near 275. Hydrobromic acid or heat and sulphuric acid cause it to change to isomeric terebic acid (A. 226, 363). y- Methyl- ethyl-itaconic Acid melts at 165 (A. 282, 283). Dimethylitaconic Acid, melting about 140, is isomeric with teraconic acid, to which it seems to sustain the same relation as citraconic acid to mesaconic acid. It HYDROMUCONIC ACIDS. DIOLEFINE DICARBOXYLIC ACIDS. 467 results on boiling teraconic acid with caustic soda (Fittig, B. 26, 2082). Methyl- ethylitaconic Acid melts at 141 (A. 282, 283). The following unsaturated dicarboxylic acids may also be mentioned : Glutaconic Acid, CH< CH 2 'QJ |j , melting at 132, is isomeric with ita,- citra,- and mesaconic acids, and ethidene malonic acid; it arises in the saponification of the dicarboxyl glutaconic esters with hydrochloric acid (A. 222, 249). It has also been obtained by the action of barium hydrate upon coumalic ester (p. 496) (A. 264, 301). Its zinc salt separates from boiling solutions. The ethyl ester, from the silver salt, boils at 237-238. The anhydride, produced by heating glutaconic acid and /3-oxyglutaric acid (Kekule), or by treating glutaconic acid with acetyl chloride, melts at 82-83 ( m - P- 87, K 2 7> 882 )- Tbe *'M* melts at 183-184. It is obtained (i) from glutaconamic acid, (2) from glutaconamide, and (3) from oxyglutaramide upon heating with sulphuric acid to 130-140. Sodium and methyl iodide convert it into glutaconmethyl imide ; nitrous acid produces an NO derivative ; distilled over zinc dust it forms pyridine, and when treated with PC1 5 , pcntachlorpyridine , C 5 C1 5 N (see constitution of pyridine) , results. fi-Chlorglutaconic Add melts at 195; it is formed from PC1 5 and acetone dicar- boxylic acid (see this") ; compare glutinic acid (p. 468). Tetrachlorglutaconic Acid melts at 109-110 (B. 25, 2697). Homologues of ghitaconic acid, see B. 23, 3179; B. 27, R. 193. . Hydromuconic Acids. 8 y ft a a/?-Acid : CO 2 H . CH 2 . CH 2 . CH = CH . CO 2 H, m. p. 169 stable form. ^7- Acid : CO 2 H . CH 2 . CH = CH . CH 2 . CO 2 H, m. p. 195 unstable form. The unstable modification is produced by the reduction of dichlormuconic acid, muconic acid (see below), and diacetylene dicarboxylic acid (p. 468). It dissolves with difficulty in cold water; potassium permanganate oxidizes it to malonic acid. It changes to the stable variety on boiling with sodium hydrate, and this permanga- nate oxidizes to succinic acid. Sodium amalgam reduces the unstable form, after its conversion into the stable variety, into adipic acid (p. 454). CH 2 :CH.CH 2 .CH.C0 2 H Allyl Succinic Acid, I ^ melts at 94. It is formed CH 2 . CO 2 H from allyl ethenyl tricarboxylic acid by the elimination of CO 2 (B. 16, 333). Allyl- Diethyl- and allylethyl succinic acids, see B. 25, 488. hwakralgbttaric Acid, (CH 3 ) 2 . CH . CH 2 . CH : C(CO 2 H)CH 2 . CH 2 . CO 2 H , formed together with di-isovaleral glutaric acid, melts at 75. C. DIOLEFINE DICARBOXYLIC ACIDS. Diallylmalonic Acid, (CH 2 = CHCH 2 ) 2 C(CO 2 H) 2 , melts at 133, and with CH 2 . CH 2 . CH 2 . C . CH 2 . CH . 2 CH 2 hydrobromic acid yields a dilactone, ] /\ .It O- -CO CO O breaks down into CO 2 and diallylacetic acid when heated (p. 289). CH = CH . CO 2 H Muconic Acid, j, , is formed when alcoholic potash acts upon CH = CH . CO 2 H the dibromide of /3}'-hydromuconic acid. It melts at 260. Dichlormuconic Acid, C 6 H 4 C1 2 O 4 , results when PC1 5 acts upon mucic acid (B. 24, R. 629). It yields /3)'-hydromuconic acid with sodium amalgam (B. 23, R. 232). 468 ORGANIC CHEMISTRY. (CH 3 ) 2 . CH . CH 2 . CH : C . CO 2 H Di-isovaleralglutaric Acid, CH 2 , melts (CH 3 ) 2 . CH . CH 2 . CH . C . CO 2 H at 220, and is obtained from glutaric acid and isovaleraldehyde with acetic anhydride, sodium ethylate or sodium (A. 282, 357). D. ACETYLENE- AND POLYACETYLENE DICARBOXYLIC ACIDS. C . CO 2 H -f 2H 2 O Acetylene Dicarboxylic Acid, III , is obtained when aqueous C . C0 2 H or alcoholic potash is allowed to act upon dibrom- and isodibrom-succinic acid (A. 272, 127). It effloresces on exposure. The anhydrous acid crystallizes from ether in thick plates, and melts with decomposition at 175. The acid unites with the haloid acids to form halogen fumaric acids. With bromine and iodine it yields dihalogen fumaric acids (p 463). Its esters unite with bromine and form dibrom- malei'c esters and dibromfumaric esters (B. 25, R. 855). With water they yield oxalacetic ester (B. 22, 2929). They combine with phenylhydrazine and hydrazine, forming the same pyrazolon derivatives as oxalacetic ester (B. 26, 1719). And with diazobenzene-imide they form phenyltriazole dicarboxylic ester (B. 26, R. 585). Oxalacetic ester and acetylene dicarboxylic ester are condensed by alcoholic potash to aconitic ester (B. 24, 127). See acetoxymaleiic anhydride (p. 495). The primary potassium salt, C 4 HKO 4 , is not very soluble in water, and when heated de- composes into CO 2 and potassium propiolate (p. 287). The silver salt breaks down readily into CO 2 and silver acetylide (A. 272, 139). The diethyl ester, boiling at 145- 148 (15 mm.), is obtained from dibromsuccinic ester with sodium ethylate (B. 26, R. 706). See also thiophene tetracarboxylic esters. C . CO 2 H Glutinic Acid, III , is obtained by the action of alcoholic potash (B. C.CH 2 C0 2 H 20, 147) upon chlorglutaconic acid (p. 467). It melts at 145-146 with evolution of carbon dioxide. /" p OO 1~F Diacetylene Dicarboxylic Acid, i \ 2 -f H 2 O, is made by the action of potassium ferricyanide upon the copper compound of propiolic acid (B. 18, 678, 2269). It assumes a dark red color on exposure to light, and at 177 explodes with a loud report. Sodium amalgam reduces it to hydromuconic acid, then to adipic acid and at the same time splits it up into propionic acid. The ethyl ester is an oil boiling at 184 (200 mm.). Zinc and hydrochloric acid decompose it and yield pro- pargylic ethyl ether. C=C . C=C . C0 2 H Tetra-acetylene Dicarboxylic Acid, | . Carbon dioxide C=C . C^C . CO 2 H escapes on digesting the acid sodium salt of diacetylene dicarboxylic acid with water, and there is formed the sodium salt of diacetylene monocarboxylic acid, CH=C.- CEECO 2 Na, which cannot be obtained in a free condition. When ferricyanide of potassium acts upon the copper compound of this acid, tetra-acetylene dicarboxylic acid is formed. This crystallizes from ether in beautiful needles, rapidly darkening on exposure to light and exploding violently when heated. Consult B. 18, 2277, for an experiment made to explain the explosibility of this derivative. TRIHYDRIC ALCOHOLS. 469 V. TRIHYDRIC ALCOHOLS: GLYCEROLS AND THEIR OXIDATION PRODUCTS. The trihydric alcohols, or glycerols, and those bodies which may be regarded as oxidation products of these, attach themselves to the dihydric alcohols (glycols) and their oxidation products. The glycerols are obtained from the hydrocarbons by the substitu- tion of three hydroxyl groups for three hydrogen atoms, linked to different carbon atoms. As the number of hydroxyl groups increases, the number of theoretically possible classes of glycerols, in contrast to the glycols, also becomes greater. These trihydric bodies are called glycerols after their most important representative. The number of possible classes of oxidation products also grows accordingly, and in the case of the trihydric alcohols that number is now 19. How- ever, this chapter of organic chemistry has been more irregularly developed than that pertaining to the dihydric derivatives, and it may be said that the glycerols serve, even to a less degree than the glycols, as starting-out material for the preparation of the various classes belong- ing here, some of which are : dioxymonocarboxylic acids, monoxy- dicarboxylic acids, diketone-mono-carboxylic acids, mono-ketone- dicarboxylic acids, tricarboxylic acids. Oxydialdehydes, oxydiketones, trialdehydes, aldehyde diketones and triketones are only slightly, if at all, represented. The same may be said of the oxyaldehyde ketones, oxyaldehydic acids, oxyketonic acids, aldehyde-carboxylic acids, and alde- hyde-ketone-carboxylic acids. i. TRIHYDRIC ALCOHOLS. Glycerol stands at the head of this, class, although it is not a triprimary alcohol, but rather a diprimary-secondary alcohol. The simplest imaginable triprimary alcohol would have the formula CH(CH 2 OH) 3 , and could be referred to trimethylmethane, CH(CH 3 ) 3 , whereas glycerol is derived from propane, and considering the struc- ture of the carbon nucleus, it is the simplest trihydric alcohol. Although it may appear unnecessary to develop all the possible kinds of trihydric alcohols and their oxidation products, as was done with the glycols, yet the oxidation products theoretically possible from glycerol will be deduced. By enlarging this scheme we really construct a comparative review of the oxygen compounds, obtainable from methane, ethane, and propane. It is also possible to tabulate the formulas of the oxygen derivatives of a hydro- carbon in such manner that the hydrogen atoms may be regarded as replaced, step by step, by hydroxyl groups, and we may indicate the number of hydrogen atoms attached to one carbon atom, which have been replaced by hydroxyl groups.* * This idea originated with A. v. Baeyer. It has the advantage that it facili- tates the deduction of the possible hydroxyl derivatives of higher hydrocarbons, and determines the degree of oxidation, etc. 47 ORGANIC CHEMISTRY. Thus, in compounds containing more than one hydroxyl attached to the same carbon atom, numbers are employed to express the formulas of ortho derivatives, usually only stable in the form of ethers. When a carbon atom, of a hydrocarbon, is joined to hydrogen, and no hydrogen atoms are replaced by hydroxyl, this is ex- pressed by a zero : Methane = CH 4 : o I II III IV oi 2 34 /H OH /OH OH .OH H ' H /OH 'OH OH \ -H. 11 v s~i * Oxi v Oil X H X H X H X H X OH Ethane = CH 3 . CH 3 : oo I II 00 10 20 CH 3 CH 3 OH CH(OH) 2 CH 3 CH CH,.OH III 30 21 C(OH) 3 CH(OH) 2 CH 2 OH IV 22 31 CH(OH) 2 CH(OH) 2 C(OH) 3 CH 2 OH V 32 C(OH) 3 CH(OH) 2 VI 33 C(OH) 3 C(OH) 3 Propane CH 3 . CH 2 . CH 3 : ooo I II III IV V VI VII VIII OOO IOO 2OO 3OO 310 32O 303 *322 323 010 020 *2IO 301 *302 321 313 110 *20I 220 311 *3I2 101 120 *202 *22I *222 III 211 *2I2 121 The following formulas correspond to these groups of numbers : 000 CH 3 . CH 2 . CH 3 Propane I: 100 CH 2 OH . CH 2 . CH 3 n-Propyl Alcohol 010 CH 3 . CHOH . CH 3 Isopropyl Alcohol II: 200 CH(OH) 2 .CH 2 .CH 3 Propionic Aldehyde O2O no CH 3 C(OH) 2 CH 3 CH 2 (OH)CH.OH.CH 3 Acetone Propylene Glycol IOI CH 2 OH.CH 2 .CH 2 OH Trimethylene Glycol III: 300 *2IO C(OH) 3 . CH 2 . CH 3 CH(OH) 2 .CH(OH)CH S Propionic Acid Unknown *20I 120 CH(OH) 2 CH 2 . CH 2 OH CH 2 OH . C(OH) 2 CH, Unknown Oxyacetone, Ketol III CH 2 OH . CHOH . CH 2 OH Glycerol IV: 310 C(OH) 3 .CHOH.CH 3 Lactic Acid 3 OI 22O *2O2 C(OH) 3 . CH 2 . CH 2 OH CH(OH) 2 .C(OH) 2 .CH 3 CH(OH) 2 .CH 2 .CH(OH) 2 Hydracrylic Acid Pyroracemic Aldehyde Unknown 211 CH(OH) 2 . CH . OH . CH 2 . OH Glycerose 121 CH 2 OH . C(OH) 2 . CH 2 OH Dioxyacetone Unknown. TRIHYDRIC ALCOHOLS. 47 1 V: 320 C(OH) 8 .C(OH)..CH, * 3 02 C(OH) 3 .CH 2 .CH(OH) 2 311 C(OH) 3 .CHOH. CH 2 OH *22i CH(OH) 2 .C(OHVCH,.OII *2I2 CH(OH) 2 . CH(OH) . CH(OH) 2 VI: 303 C(OH) 3 .CH 2 .C(OH) 3 321 C(OH) 3 . C(OH) 2 . CH,OH *3I2 C(OH) 3 .CHOH.CH(OH) 2 *222 CH(OH), . C(OH) 2 . CH(OH) 2 VII: 322 C(OH) 3 .C(OH) 2 .CH(OH) 2 313 C(OH) 3 . CH(OH) . C(OH) 3 VIII: 323 C(OH) 3 . C(OH) 2 .C(OH) 3 There are 29 imaginable hydroxyl substitution products of propane, and eleven of these should be regarded as oxidation products of glycerol, which will again be arranged together under their usual formulas that is, their ortho- formulas minus water: Pyroracemic Acid Unknown Glyceric Acid Unknown Unknown Malonic Acid Oxypyroracemic Acid Unknown Unknown Unknown Tartronic Acid Mesoxalic Acid CH 2 OH CH . OH CH 2 OH (in) Glycerol CHO CHOH CH 2 OH (2ir) Glycerose CHOH CHOH CH 2 OH CH 2 . OH (311) (i 21 ) Glyceric Acid Dioxyacetone CHO CHOH CHO (212) Unknown CO 2 H CO 2 H CHO CHOH CHOH CO CHO C0 2 H CHO (312) (313) (222) Unknown Tartronic Acid Unknown CHO CO 2 H I 1 CO CO 1 1 CH 2 .OH CH 2 . OH (221) (321) Unknown Oxypyro- racemic Acid. C0 2 H CO 2 H to C(OH) 2 I | CHO C0 2 H (322) (323) Unknown Mesoxalic Acid. Glyceric acid, tartronic acid, and mesoxalic acid are the only accurately known rep- resentatives of these eleven oxidation products of glycerol. The glyceroses and dioxyacetone have not been prepared in a pure state. Crude glycerose is a mixture of these two substances. Oxypyroracemic acid has received very little study. Three hydrogen atoms in glycerol can be replaced by alcohol or acid radicals ; the products are ethers and esters : OH OH O.C 2 H 3 Acetin row C 3 H 5 {0. OH C 2 H 3 C 2 H 3 Diacetin The haloid esters are the halohydrins : C 3 H 5 (OH) 2 C1 Monochlorhydi in C 3 H 5 (OH)C1 2 Dichlorhydrin O.C 2 H 3 O.C 2 H 3 IO.C 2 H 3 Triacetin. C 3 H 5 C1 3 Trichlorhydrin. Formation. The trihydric alcohols are obtained (i) by heating the bromides of the unsaturated alcohols with water ; or (2) Upon oxidizing the unsaturated alcohols with potassium per- manganate (B. 28, R. 927). Glycerol [Propantriol], CH 2 . OH . CH . OH . CH 2 OH, is pro- duced in small quantities in the alcoholic fermentation of sugar; hence 472 ORGANIC CHEMISTRY. is contained in wine. It is prepared exclusively from the fats and oils, which are glycerol esters of the fatty acids (p. 122). When the fats are saponified by bases or sulphuric acid, they decompose, like all esters, into fatty acids and the alcohol glycerol. Glycerol is also formed from synthetic glycerol trichloride by heat- ing it with water to 170, and from allyl alcohol when it is oxidized with potassium permanganate. Historical Scheele discovered glycerol in 1779, when he saponified olive oil with litharge, in making lead plaster. Chevreul, who recognized ester-like derivatives of glycerol in the fats and fatty oils, introduced the name glycerol, and in 1813 pointed to similarities between it and alcohol. The composition of glycerol was established in 1836, by Pelouze. Berthelot and Lucca (1853), and later Wtirtz (1855), explained its constitution, and proved that it was the simplest trihydric alcohol, the synthesis of which Friedel and Silva (1872) effected from acetic acid: CH 3 CH 3 CH 3 CH,C1 CILOH I ' (3) I (4) I (5) I (6) I CHOH > CH > CHC1 -> CHC1 > CHOH CH 2 CH 2 C1 CH 2 C1 CH 2 OH (l) Acetone is obtained from calcium acetate. (2) Acetope by reduction passes into isopropyl alcohol. (3) Propylene results when anhydrous zinc chloride with- draws water from isopropyl alcohol. (4) Chlorine and propylene yield propylene chloride. (5) Propylene chloride and iodine chloride unite to form propenyl trichlo- ride or allyl trichloride, the trichlorhydrin of glycerol. (6) Glycerol is produced when trichlorhydrin is heated with much water to 160 (B. 6, 969). Metallic iron and bromine convert propylene bromide into tribromhydrin, which silver acetate changes to triacetin. Bases saponify the latter and glycerol results (B. 24, 4246). Preparation. At present glycerol is produced in large quantities in the manufac- ture of stearic acid ; the fats are saponified by means of superheated steam, convert- ing them directly into glycerol and fatty acids. In order to obtain a pure product the glycerol is again distilled under diminished pressure. Properties. Anhydrous glycerol is a thick, colorless syrup, of spe- cific gravity 1.265 at 15. Below o it solidifies to a white, crystal- line mass, which melts at 4-17. Under ordinary atmospheric pressure it boils at 290 (cor.) without decomposition ; under 12 mm. at 170. With superheated steam it distils entirely unaltered. It has a pure, sweet taste, hence the name glycerol. It absorbs water very energetically when exposed and mixes in every proportion with water and alcohol, but is insoluble in ether. It dissolves the alkalies, alka- line earths and many metallic oxides, forming with them, in all prob- ability, metallic compounds similar to the alcoholates (p. 124). Transformations. (i) When glycerol is distilled with dehydrating substances, like sulphuric acid and phosphorus pentoxide, it decom- poses into water and acrolem (p. 208). It sustains a similar and par- tial decomposition when it is distilled alone. (2) When fused with caustic potash, it evolves hydrogen, and yields acetic and formic acids. (3) Platinum black, or dilute nitric acid, oxidizes it to glyceric and tartronic acids, while niter and bismuth nitrate change it to mesoxalic acid (B. 27, R. 666). Under energetic oxidation the products are oxalic acid, glycollic acid, glyoxylic and other acids. (4) Moderated GLYCEROL ESTERS OF INORGANIC ACIDS. 473 oxidation (with nitric acid or bromine) produces glycerose, which con- sists chiefly of glyceraldehyde and dioxyacetone, CO(CH 2 . OH). 2 . This unites with CNH and forms trioxybutyric acid (B. 22, 106; 23, 387): :MO !:HOH Glyceral- dehyde CH,OH ( ( } CH . OH C(OH) 2 CO 2 H CO 2 H Tartronic Mesoxalic Acid Acid. CH 2 OH Dioxy- acetone CH 2 .OH Glycerol Glycerose (5) Phosphorus iodide or hydriodic acid converts it into allyl iodide, isopropyl iodide, and propylene (p. 113). (6) In the presence of yeast at 20-30 it ferments, forming propionic acid. By schizomy- cetes fermentation, induced by Butyl bacillus (B. 30, 451), normal butyl alcohol (p. 125) and trimethylene glycol result (p. 295). ^ (7) When glycerol is distilled with ammonium chloride, ammonium phosphates and other ammonium salts, /3-picoline, as well as 2 5-dimethyl pyrazine, results. Under certain conditions it is only the latter which is produced (B. 26, R. 585 ; 24, 4105 ; 27, R. 436, 812). Uses. Glycerol is applied as such in medicine. It is also used as a lubricant in watches. Duplicating plates and hectographs consist of mixtures of gelatine and glycerol. The bulk of glycerol is consumed in the manufacture of "nitrogly- cerine" (p. 474). Glycerol Homologues. \.2.i>- Butyl glycerol, CH 3 . CH(OH) . CH(OH) . CH 2 OH, boiling at 172-175 (27 mm.), is prepared from crotonylalcohol dibromide (p. 131). [l.2.$-Pentantrior], C 2 H 5 . CH(OH) . CH(OH) . CH 2 . OH, boils at 192 (63 mm. ) ; [2.3.4- AnAm/rio/l, CH s CH(OH) . CH(OH) . CH(OH) . CH 3 , boils at 180 (27 mm.); j3- Ethyl 'glycerol, CH 3 . CH 2 C(OH)(CH 2 OH) 2 ,boils at 186-189 (68 mm.). These and other glycerols result upon oxidizing unsaturated alcohols with potassium permanganate (B. 27, R. 165; 28, R. 927). Penta-glycerol, CH 3 C(CH 2 . OH) 3 , melts at 199. It is obtained by the action of lime upon propyl aldehyde and form- aldehyde (A. 276, 76). \\4.$-Hcxantriol\, CH 3 . CH(OH) . CH(OH) . CH 2 . CH 2 . CH 2 OH, boiling at 181 (10 mm.), and some other isomerides and higher homologues have been ob- tained from the addition products of bromine and hypochlorous acid with the corre- sponding unsaturated alcohols. A. GLYCEROL ESTERS OF INORGANIC ACIDS. (a] Glycerol Haloid Esters. These are called halohydrins (p. 471). There are two possible isomeric mono- and di-halohydrins. They are distinguished as a-halo- hydrins and /3-halohydrins : CH 2 .C1 CH 2 .OH CH 2 C1 CH 2 OH CH.OH CH.C1 CH.OH CHC1 CH 2 .OH CH 2 OH CH 2 C1 CH 2 . Cl a-Chlorhydrin j3-Chlorhydi in a-Dichlorhydrin /3-Dichlorhydrin. 40 474 ORGANIC CHEMISTRY. The monohalohydrins may also be regarded as halogen substitution products of propylene and trimethylene glycol, while the dihalohydrins are probably the dihalogen substitution products of propyl and isopropyl alcohol (p. 125). a- Monohalohydrins are formed when the haloid acids act upon glycerol, and by the interaction of water and epihalohydrins. a-Chlorhvdrin, CH 2 OH . CH . OH . - CH a Cl, boils at 139 (18 mm.). a-Bromhvdrin boils at 180 (10 mm.). $-Chlor- hydrin, CH 2 OH . CHC1 . CH 2 OH, boils at 146 (18 mm.). It is obtained from allyl alcohol and C1OH. a-Dihalohydrins are produced when the haloid acids (A. 208, 349) act upon glycerol, and upon the epihalohydrins (p. 477) (^- IO 557)- Potassium iodide changes the chlorine derivative into the iodine compound (pp. 124, 126). a-Dichlorhydrin, CH 2 C1. CH . OH . CH 2 C1, is a liquid, with ethereal odor, of sp. gr. 1.367 at 19, and boils at 174. It is not very soluble in water, but dissolves readily in alcohol and ether. When heated with hydriodic acid it becomes isopropyl iodide; sodium amalgam produces isopropyl alcohol. When sodium acts on an ethereal solution of a-dichlorhydrin, we do not get trimethylene alcohol, but allyl alcohol as a result of molecular transposition (B. 21, 1289). Chromic acid oxidizes it to /3-dichloracetone (p. 216) and chloracetic acid. Caustic potash converts it into epicblorhydrin (p. 477). a-Dibromhydrin, CH 2 Br . CH(OH) . CH 2 Br, is an ethereal-smelling liquid, which boils at 219 ; its sp. gr. at 18 is 2. 1 1. a-Di-iodhydrin is a thick oil of specific gravity 2.4, and solidifies at 15. The $-dihalohydrins result from the addition of halogens to allyl alcohol. fi-Dichlorhydrin boils at 182-183; its sp. gr. = 1.379 at o. Sodium converts it into allyl alcohol. Hydriodic acid changes it to isopropyl iodide. Fuming nitric acid oxidizes it to o/3-dichlorpropionic acid. Both dichlorhydrins are changed to epichlorhydrin by the alkalies. fi-Dibromhydrin boils a,t 212-214. Trikalokytfrin* form when halogens are added to the allyl halides; also in the action of phosphorus haloids upon the dihalohydrins, and when iodine chloride acts upon propylene chloride, and bromine and iron upon propylene bromide and tri- methylene bromide (B. 24, 4246). Trichlorhydrin, Glyceryl Chloride, l.2.3-trichlorpropane, CH 2 C1 . CHC1 . CH 2 C1, boils at 158. Tribromhydrin fuses at 16, and boils at 220. Silver acetate converts it into glycerol triacetyl ester. When this is saponified it yields glycerol (p. 472). 0) Glycerol Esters of the Mineral Acids Containing Oxygen. The neutral nitric acid ester nitroglycerine (discovered by Sobrero in 1847) is tne most important member of this class. Nitroglycerine, glycerol nitrate, CH 2 (ONO 2 ) . CH,ONO 2 ) . CH 2 (ONO 2 ), is pro- duced by the action of a mixture of sulphuric and nitric acids upon glycerol. The latter is added, drop by drop, to a well-cooled mixture of equal volumes of concen- trated nitric and sulphuric acids, as long as it dissolves; the solution is then poured into water, and the separated, heavy oil (nitroglycerine) is washed with water and dried by means of calcium chloride. Nitroglycerine is a colorless oil, of sp. gr. 1.6, and becomes crystalline at 20. It volatilizes very energetically at 160 (15 mm. pressure) (B. 29, R. 41). It has a sweet taste, and is poisonous when taken inwardly. It is insoluble in water, dis- solves with difficulty in cold alcohol, but is easily soluble in wood spirit and ether. Heated quickly, or upon percussion, it explodes very violently (Nobel's explosive oil] ; mixed with kieselguhr it forms dynamite, and 'with nitrocellulose, smokeless powder. Alkalies convert nitroglycerine into glycerol and nitric acid ; ammonium sulphide also regenerates glycerol. Both reactions prove that nitroglycerine is not a nitro- compound, but a nitric acid ester. ULVCER1DES. 475 Glycerol- Nitrite i C 3 H 5 (O . NO) 3 , is formed by the action of N 2 O 3 upon glycerol. It is isoraeric with Tnnilropropane (B. 16, 1697). Glyicrol-SnJphnric Acid, C 3 H 5 \ L CQ T4' ls ^ ormec ^ by mixing I part gly- cerol with I part of sulphuric acid. Glycerol- Phosphoric Acid, C 3 H 5 <^x pj 2 , TT , occurs combined with the fatty acids and choline as lecithin (see this) in the yolk of eggs, in the brain, in the bile, and in the nervous tissue. It is produced on mixing glycerol with metaphosphotic acid. The free acid is a stiff syrup, which decomposes into glycerol and phosphoric acid when it is heated with water. It yields easily soluble salts wirh two equivalents of metal. The calcium salt is more insoluble in hot than in cold water ; on boiling its solution, it is deposited in glistening leaflets. Glycerol mercaptans are produced when chlorhydrins are heated with alcoholic solutions of potassium sulphydrate. B. GLYCEROL FATTY ACID ESTERS, GLYCERIDES. (a] Formic Acid Esters, Monoformin, C 3 H 5 (OH) 2 OCHO, is volatile under diminished pressure. It is supposed that it is formed on heating oxalic acid and glycerol. "When k is heated alone it breaks down into allyl alcohol (p. 130), -water, and carbon dioxide. Diformin is most certainly produced under these conditions. Mono- formin also results from the action of a-monochlorhydrin upon sodium formate. Diformin, C 3 H.(OH) . (O . CHO) 2 , boils at 163-166 (20-30 mm ). (b] Acetic Esters, or Acetins, result when glycerol and acetic acid are heated together: Monacetin at 100 ; at 200 : Diacetin, C 3 H 5 (O. COCH 3 ) 2 (OH), boil- ing at 259-260 (B. 24, 3466); at 250: Triacetin, C 3 H 5 (O . COCH 3 ) 3 , boiling at 258, occurs in small quantities in the seed of Evonymus europaus, and has also been obtained from tribromhydrin (p. 476). (c] Tributyrin, C 3 H 5 (OC 4 H 7 O) 3 , occurs in cow's butter (p. 247). (CH . OH, boils at 193 (A. 289, 29). Benzal glycerol melts at 66 (B. 27, 1536). Acetone Glycerol, (CH 3 ) 2 C< ' ^ CH2QH , or (CH 3 ) 2 CCH . OH, boils at 83 (11 mm.) (B. 28, 1169). CH . CH 2 OH Glycide Compounds : Glycide, Epihydrin Alcohol, O< I , boiling CH 2 at 162, sp. gr. 1.165 (o), is isomeric with acetyl carbinol. This body manifests the properties both of ethylene oxide and of ethyl alcohol. It is obtained from its acetate by the action of caustic soda or barium hydrate. Glycide and its acetate reduce ammoniacal silver solutions at ordinary temperatures. Glycerol also forms polyglycerols. Thus glycerol yields Diglycerol, (HO) 2 . C 3 - H 5 OCoH-(OH) 2 , when it is treated with chlorhydrin or aqueous hydrochloric acid at 130 DIOXYALDEHYDES. 477 results from the action of sodium acetate upon epichlorhydrin in absolute alcohol, and the subsequent saponification of diglycide acetate with caustic soda. /"^TT /~* T_T /~M Epichlorhydrin, O< I 2 , is isomeric with monochloracetone, and con- CH 2 stitutes the starting-out material for the preparation of the glycide compounds. It is obtained from both dichlorhydrins by the action of caustic potash or soda (analo- gous to the formation of ethyl ene oxide from glycolchlorhydrin (p. 298) : CH 2 C1 1 -HC1 CH 1 >o S- PIT ' ^' ma ^ ^ e cons idered tne anhydride of an unsatu rated dioxyketone. 4. OXYALDEHYDE KETONES. Oxypyroracemic Aldehyde, CHO . CO.CH 2 OH, is the simplest oxyaldehyde ketone. It is only known in the form of its osazone, melting at 134, and is pro- duced by the interaction of phenylhydrazine and dioxyacetone (B. 28, 1522). 5. OXYDIKETONES. a-Dibromethyl Ketole, CH 3 . CBr 2 COCH 2 OH, melting at 85, and formed from brom-tetrinic acid and bromine, is a derivative of the simplest oxydiketone, CH 3 . CO .- CO.CH 2 OH. Oxymethylene-Acetyl Acetone, (CH 3 CO) 2 C = CHOH, melting at 47 and boiling at 100 (20 mm.), 199 (ord. pressure), is a strong acid, stronger than acetic acid. It is soluble in aqueous alkaline acetates. It absorbs oxygen rapidly from the air, and when gently heated with water and mercuric oxide it decomposes into car- bonic acid and acetyl acetone. Its copper salt melts at 214. Etoxymethylene- Acetyl Acetone, (CH 3 . CO) 2 C = CHOC 2 H 5 (liquid, boiling at 141 under 16 mm.), results from the condensation of acetyl acetone with ortho- formic ether. Water decomposes it into alcohol and the preceding body. Ammonia converts it into aniido-methylene acetyl acetone, (CH 3 . CO) 2 C = CH . NH 2 , melting at 144. With acetyl acetone it forms niethenyl-bisacetyl acetone , (CH 3 . CO) 2 C := CH CH (CO.CH 3 ) 2 , melting at 118. Ammonia changes it to diacetyl-lutidine. By the withdrawal of water it becomes diacetyl metacresol. D1OXYMONOCARBOXYLIC ACIDS. 479 Oxymethylene-acetyl acetone, as well as the corresponding derivatives of aceto- acetic ester and malonic ester, can be considered as formic acid in which the intra- radical oxygen has been replaced by a carbon atom carrying two negative groups (X) : O = CH . OH *>C = CH . OH Formic Acid Oxymethylene Compounds. As these bodies are strong monobasic acids, the group X 2 C = would seem to exert an influence upon the carbon atom combined with it, or upon the hydroxyl in union with the carbon atom, just as is done by oxygen that is joined with two bonds. It is true that the influence may not be so great as in the latter case. The compounds just described are the first of the complex substances, containing only C, H, and O, which, without carboxyl, still approach the monocarboxylic acids (formic excepted) in acidity. Indeed, in some instances they surpass them in this respect (B. 26, 2731 ; privately communicated by L. Claisen). 6. ALDEHYDE DIKETONES. The following are derivatives of the dialdehydes corresponding to mesoxalic acid (see this) : (1) Diisonitrosoacetone, CH(N . OH) . CO . CH(N . OH), melts at 144 with decomposition. It results when nitrous acid acts upon acetone dicarboxylic acid. (2) Trioximidopropane, CH(N. OH)C(N . OH) . CH(N . OH), melting at 171, is the result of the action of hydroxvlamine upon diisonitrosoacetone (B. 21, 2989). (3) Propanon diphenyl hydrazone, C 6 H 5 NHN : CH . CO . CH : N . NHC 6 H 5 , melting at 175, with decomposition, is formed from acetone dicarboxylic acid and diazobenzene. (4) Propanon triphenylhydrazone, melts at 166. It consists of yellow leaf- lets. It results when the preceding body is treated at 120 with phenylhydrazine (B. 24, 3259; 27, 219). 7. TRIKETONES. Pentantrion, C H 3 . CO . CO . CO . CH S , is the simplest triketone. It is only known in the form of a phenylhydrazine derivative of benzene azoacetyl acetone, C 6 H 5 NH . - N : C(COCH 3 ) 2 , which is produced when diazobenzene salts act upon sodium acetyl acetone (B. 25, 74^), an d ln that of an oxime, isontirosoacetyl acetone, HO . N : - C(COCH 3 ) 2 (B. 27, R. 585). Diacetyl Acetone, [2.$.(>-Heptantrion'], z.^.^-Trioxoheptan, CO(CH 2 COCH 3 ) 2 , melting at 49, results when baryta water acts upon 2.6-dimethylpyrone, CO< - CfCH)^^' Hydrochloric acid separates it from the barium salt. It decomposes spontaneously into water and dimethylpyrone (A. 257, 276). Ferric chloride imparts a deep, dark red color to it. Its dioxime melts at 68, and readily passes into an anhydride (B. 28, 1817), melting with decomposition at 242. 8. DIOXYMONOCARBOXYLIC ACIDS. The acids of this series bear the same relation to the glycerols that the lactic acids sustain to the glycols. They can also be called dioxy- derivatives of the fatty acids (p. 329). They may be artificially pre- 480 ORGANIC CHEMISTRY. pared by means of the general methods used in the production of oxyacids, and also by the oxidation of unsaturated acids with potas- sium permanganate (p. 330) (B. 21, R. 660; A. 283, 109). Glyceric Acid, C 3 H 6 O 4 (dioxypropionic acid), [Propandiol Acid], is formed: (i) By the careful oxidation of glycerol with nitric acid (method of preparation, B. 9, 1902; 10, 267; 14, 2071), or by oxidizing glycerol with mercuric oxide and baryta water (B. 18, 3357), or with silver chloride and sodium hydroxide (B. 29, R. 545). The calcium salt is decomposed with oxalic acid (B. 24, R. 653) : CH 2 (OH) . CH(OH) . CH 2 (OH) -f O 2 = CH 2 (OH) . CH(OIl) . CO . OH -f H 2 O. (2) By the action of silver oxide upon /9 chlorlactic acid, CH 2 C1 . - CH(OH) . CO 2 H, and a-chlorhydracrylic acid, CH 2 (OH) . CHC1 . - CO 2 H (p. 341). (3) By heating glycidic acid with water (p. 481). Glyceric acid forms a syrup which cannot be crystallized. It is easily soluble in water, alcohol, and acetone. It is optically inactive, but as it contains an asymmetric carbon atom (p. 45), it may be changed to active laevo-rotatory glyceric acid by the fermentation of its ammonium salt, through the agency of Penicillium glaucum. Bacillus ethaceticus, on the other hand, decomposes inactive glyceric acid so that the laevo-rotatory glyceric acid is destroyed and the dextro-rotatory acid remains (B. 24, R. 635, 673). Transformations. When the acid is heated above 140 it decomposes into water, pyroracemic and pyrotartaric acids. When fused with potash it forms acetic and formic acids, and when boiled with it, yields oxalic and lactic acids. Phosphorus iodide converts it into /5-iodpro- pionic acid. Heated with hydrochloric acid, it yields a-chlorhydra- crylic acid and a/9-dichlorpropionic acid. When glyceric acid is preserved a while, it probably forms a lactide or anhydride. This is sparingly soluble, and crystallizes in fine needles. Its calcium salt, (C 3 H 5 O 4 ) 2 Ca -)- 2H 2 O, dissolves readily in water. The lead salt, (C 3 H 5 O 4 ) 2 Pb, is not very soluble in water. The ethyl ester is formed on heating glyceric acid with absolute alcohol. The rotatory power of the optically active glyceric esters increases with the molecular weight (B. 26, R. 540), and attains its maximum with the butyl ester (B. 27, R. 137, 138). The homologues of glyceric acid have been obtained (i) from the corresponding dibromfatty acids ; (2) from the corresponding glycidic acids on heating them with water (A. 234, 197) ; and (3) by oxidizing the corresponding unsaturated carboxylic acids (p. 281) with potassium permanganate (A. 268, 8; B. 22, K. 743). There are three dioxybutyric acids : (1) a/3-Dioxybutyric Acid, CH 3 . CH(OH) . CH(OH) . CO 2 H, /3-Methylgly- ceric Acid. It melts at 74-75. (2) /3y-Dioxybutyric Acid, CH 2 (OH) . CH(OH) . CH 2 . CO 2 H, is a thick oil. (3) Dioxyisobutyric Acid, CH 2^^>C(OH) . CO 2 H, a-methyl glyceric acid, melts at IOO. yrf-Dioxyvaleric Acid, CH 2 (OH) . CH(OH)CH 2 . CH 2 . CO 2 H, rapidly decom- poses into water and an oxylactone. Tigliglyceric Acid melts at 88, and Angli- glyceric Acid melts at III (A. 283, 109). a/3-Dioxyisoctylic Acid, (CH 3 X 2 CH . CH 2 . CH 2 . CH(OH)CH(OH)CO 2 H, GLYCIDIC ACIDS. 481 melts at 106 (A. 283, 291). a-Isopropyl-/3-isobutyl Glyceric Acid melts at 154 (B. 29, R. 508). Dioxyundecylic Acid, CnH M (OH) f C^, from undecylenic acid, melts at 84-86. Dioxystearic Acid, C 18 H 34 (OH) 2 O 2 , from oleic acid, melts at 136. Dioxybehenic Acid, C 22 H 42 (OH) 2 O 2 , from erucic acid, melts at 136. Glycidic Acids are obtained from the addition products of hypochlorous acid and unsaturated dicarLoxylic acids, through the agency of alcoholic potash (A. 266, 204). Like ethylene oxide, they take up the haloid acids, water, and ammonia, the products being chloroxyfatty acids or dioxy fatty acids, and amido-oxy fatty acids. CH . CO 2 H Glycidic Acid, Epihydrinic Acid, O<^ I , is isomeric with pyroracemic CH 2 acid. It is produced, like epichlorhydrin (p. 477), from a-chlorhydracrylic acid and /3-chlorlactic acid by means of alcoholic potash. Glycidic acid, separated from its salts by means of sulphuric acid, is a mobile liquid miscible with water, alcohol, and ether. It is very volatile and has a piercing odor. The free acid and its salts are not colored red by iron sulphate solutions (distinction from isomeric pyroracemic acid). It combines with the haloid acids to /3-halogen lactic acids, and with water, either on boiling or on standing, it yields glyceric acid. Its ethyl ester, obtained from the silver salt with ethyl iodide, melts at 162. It resembles malonic ester in its odor (B. 21, 2053). ^Methyl Glycidic Acid, O<^ i, ' , is known in two modifications. The CH . CH 3 one melting at 84 unites to a/3-dioxybutyric acid with water. The other modifica- /~-TT C*\\ PO \\ rion is a liquid. Epihydrin-carboxylic Acid, O< I " 2 , melting at 225, CH 2 is obtained from its nitrile, which results from the action of KCN upon epichlorhy- drin (p. 477). n- Methyl Glycidic Acid, O< I ' ' 2 , consists of shining leaf- CH 2 lets. The ethvl ester boils at 162-164 (B. 21, 2054). a/3-Dimethyl Glycidic CfCHOOXH Acid, O< I ' , melts at 62 (A. 257, 128). /?/3-Dimethyl Glycidic CHCH 3 Acid. See A. 292, 282. Oxylactones are obtained from some of the dioxyacids, which contain an hydroxyl group in the y-position with reference to the carboxyl group : HO . CH 2 . CH O Oxyvalerotactone, \ i , boiling at 300-301, results from the action of potassium permanganate (A. 268, 61) upon allyl acetic acid. Oxycaprolactone and Oxyisocaprolactone, C 6 H 10 O 3 , are colorless liquids, into which the oxidation pro- ducts of hydrosorbic acid, by means of KMnO 4 , rapidly pass on liberation from their barium salts (A. 268, 34). Oxyisoheptolactone, (CH 3 ) 2 CH . CH . CH(OH) . CH 2 . COO, melts at 112. Oxyisoctolactone, (CH 3 ^ 2 CH . CH 2 . CN . CH(OH)CH 2 . CO . O, melts at 33 (A. 283, 278, 291). Monamido-oxyacids : Serin, CH 2 (OH) . CH(NH 2 ) . CO. 2 H, a-amidohydra- crylic acid, is obtained by boiling serecin with dilute sulphuric acid. It forms hard crystals, soluble in 24 parts of water at 20, but insoluble in alcohol and ether. Being an amido-acid it has a neutral reaction, but combines with both acids and bases. Nitrous acid converts it into glyceric acid. Isomeric p-amido-lactic acid, CH ? (NH 2 ) . CH(OH) . CO 2 H, is obtained from /3-chlorlactic acid and glyciclic acid by the action of ammonia (B. 13, 1077). It dissolves with more difficulty in water than serin. Homologues of the monoamido-oxyacids have been prepared by the union of homologous glycidic acids with ammonia. Diamido-carboxylic te\te.Diamidopropionic Acid, CH 2 NH 2 CHNH 2 CO 3 H, 41 402 ORGANIC CHEMISTRY. has been obtained by the action of ammonia upon a/3-dibrompropionic acid. Other similar acids have been found in the decomposition products of the albuminoid bodies. 9. OXYKETONE CARBOXYLIC ACIDS. Oxypyroracemic Add, [Propanolon Acid], CH 2 OH. CO . CO 2 H, is formed when caustic soda acts upon collodion wool (B. 24, 401). Tribrotmnethylketol, CH 2 OH . - CO . CBr 3 . See tetronic acid. Ethoxyl-acetoacetic Ester, CH 2 . O . C 2 H 5 . CO . CH 2 . COOC 2 H 5 or CH 3 CO . CH- (OC 2 H 5 )CO 2 C 2 H 5 , boils at 105 (14 mm.). It is obtained by reducing ethoxyl chlor- acetoacetic ester, the condensation product from chloracetic ester and sodium. Demarcay acted with alcoholic caustic potash upon the y-mono-brom-mono-alkylic acetoacetic esters and obtained tetrinic acid and its homologues, which may be re- garded as y-lactones of the oxyketone carboxylic acids : COCH 2 Br COCH 2 v CH 8 CH . COOC 2 H 5 ~~ *~ CH 3 . CH . Tetrinic Acid. Michael was the first to declare that tetrinic acid was a lactone with the preceding formula. L. Wolff discovered the parent substance of tetrinic acid, and named it tetronic acid, after which tetrinic acid received the name a-methyl tetronic acid (A. 291, 226). The salts of tetronic acid and the a-alkylic tetronic acids are derived from the hydroxyl formula isomeric with the ketone formula. The latter is preferred for the free acids. C*C\ /^T T Tetronic Acid, i ' 2 >O, melting at 141, is produced when sodium amalgam x^ilov-'W CO CH 2 acts upon bromtetronic acid, i ^>O, melting at 183. This results when CHBr CO dibromacetoacetic ester is heated. Dibromtetronic Acid, i 2 ^>O, is formed CBr 2 CO when bromine acts upon bromtetronic acid. It consists of white, readily soluble plates. It slowly decomposes at 174 with CO 2 -evolution into tribrommethylketol, CBr 3 . CO . CH 2 . OH, and bromtetronic acid. C*C\ f T-T Tetrinic Acid, a- Methyl Tetronic Acid, i [ 2 >O, melting at 189, CH 3 CH . CO boils with partial decomposition at 292. It results on heating y-brom-metbylaceto- acetic ester or by treating it with alcoholic potash. Heated with water to 200, it breaks down into ethyl ketol (p. 317) and CO 2 , and when it is boiled with barium hydrate it yields glycollic acid and propionic acid. Chromic acid oxidizes it to diacetyl and CO 2 (A. 288, i). Pentinic Acid, a-Ethyltetronic Acid, melts at 128. Hexinic Acid, a- Propyltetronic Acid, melts at 126. Heptinic Acid, a- Isobrdyltetronic Acid, melts at 150. y-Methoxyldimethylacetoacetic Ester, CH 3 O . CH 2 . CO . C(CH,) 2 CO 2 C 2 H ft , melts at 70 and boils at 241. It is formed when methyl alcoholic sodium methylate acts upon y-brom-dimethylacetoacetic ester (B. 30, 856). The following are derivatives of a-oxy-/3-oxobutyric acid : Nitroinethylisoxazolon, N O \( I > decomposing at 123, results when oximidomethylisoxazolon CH . C ALDEHYDOKETONE CAKBOXYLIC ACIDS. 483 is oxidized with nitric acid (B. 28, 2093). a-Amidoaceloacetic Ester , CH 3 . CO . - CH . NH 2 . CO 2 . C 2 H., is produced in the reduction of isonitrosoacetoacetic ester with stannous chloride (B. 27, 1142). a-honitrainineacetoacetic Ester, CH 3 . CO. - CNa. (N 2 () 2 Xa)CO 2 . C 2 H 5 , is only known in the form of its sodium salt. This is produced when NO acts upon acetoacetic ester dissolved in alcohol in the presence of sodium ethylate ( B. 28, 1785) ; compare also isonitramine acetic acid, p. 361. a- Hydro. \vUerulinic Add, CH 3 . CO . CH 2 CH(OH)CO 2 H, melts at 103-104, and .\-Hydroxylcevulinic Acid, CH 3 . CO. CH(OH) . CH 2 . CO..H, is an oil. They are obtained from the corresponding bromlaevulinic acids (A. 264, 259). Oxymethylene-acetoacetic ester, HO . CH = ^COO^ 5 ' boilin at 95 ( 2I mm -) results, by the action of water, from Ethoxymethylene Acetoacetic Ester, C,H 5 O.- X-.TT f TT CH = C<(V) 2 CH 3 > boiling at 149-150 (15 mm.). This is produced on heat- ing the reaction product of orthoformic ester and acetoacetic ester with acetic anhydride (B. 26, 2730). Oxymethylene acetoacetic ester is a strong acid (see oxymethylene acetylacetone, p. 478). It is readily soluble in alkaline acetates and insoluble in water. The copper salt melts at 156. Ethoxymethylene acetoacetic ester and ammonia yield amidomethylene acetoacetic ester, (C 6 H g O 3 ) = CH . NH 2 , melting at 55, and it combines with acetoacetic ester to methenylbisacetoacetic ester, (C 6 H 8 O 3 ) : CH . (C 6 H 9 O 3 ), melting at 96. Ammonia changes the latter to lutidine dicarboxylic ester, while sodium methylate converts it into metaoxyuvitic acid (private communication from L. Claisen). Ketoxystearic Acid, CH 3 [CH 2 ] 5 CH[OH]CH 2 . CH, . CO[CH 2 ] 7 CO 2 H. See ricin- oleic acid, p. 286. a-Mesityloxide Oxalic Acid (see olefine diketone carboxylic acids, p. 485). 10. ALDEHYDOKETONE CARBOXYLIC ACIDS. Glyoxyl Carboxylic Acid, CHO . CO . CO 2 H, is not known. Uric Acid may be looked upon as the diurelde of this half- aldehyde of mesoxalic acid. Di-isonitroso- propionic Acid. HO . N : CH . C : N(OH) . CO 2 II, is the dioxime of glyoxyl car- boxylic acid. It is obtained from dibrompyroracemic acid. It is known in two modi- fications, the one melting at 143, the other at 172 (B. 25, 909). Fitrazancar- N c co \\ boxylic Acid, O<^ '. pjr 2 , melting at 107, is the anhydride of this dioxime. It results from the oxidation of furazan-propionic acid with KMnO 4 . Sodium hydrox- ide causes it to rearrange itself into cyanoximido-acetic acid (A. 260, 79 ; B.24, 1167). Muco-oxychloric acid and muco-oxybromic acid (A. 9, 148, 160) are probably de- rivatives of an aldehydo-ketonic acid, CHO . CH 2 . CO . CO 2 H, or of an unsatu- rated oxyaldehydic acid, CHO . CH = C(OH)CO 2 H. Glyoxylpropionic Acid, HCO . CO . CH 2 . CH 2 . CO 2 H, is formed, along with diacetyl, when /M-dibromlsevulinic acid is boiled with water. It is a yellow crust. It passes into succinic acid upon oxidation. Its oxime is yb-dioxiinido-valeric acid, HC : N (OH) . C :,N(OH ) . CH 2 . CH 2 . CO 2 H, meltingat 1 36. Concentrated sulphuric acid changes it into the anhydride, FiirazanpropiomcAcid, O<^ \ c^** 2 ' CH 2 CO 2 H > melting at 86. Sodium hydroxide converts this acid into cyanoximidobutyrit acid (see this), while with potassium permanganate it yields furazancarboxylic acid. CO l-J Glyoxylisobutyric Acid, I 2 , melting at 138, is obtained from 2 OH O CO the isomeric dioxyacetyldimethyl acetic acid lactone, \ / , melting at CH.CO.C(CH 3 ) 2 i6S, by repeated precipitation of its boiling alcoholic solution with water, or by its solution in soda and its immediate subsequent precipitation by hydrochloric acid. 44 ORGANIC CHEMISTRY. The lactone was obtained on treating y-methoxydimethyl acetoacetic ester with bromine, and then decomposing the mono-brom-substitution product with water (B. 30, 856). II. DIKETONE CARBOXYLIC ACIDS. Paraffin Diketone Dicarboxylic Acids, a/3-Diketo- or a/3- Dioxo- butyric Acid, CH 3 . CO . CO . CO 2 H. This acid is not known in a free condition. Two oximes are derived from it: Isonitroso-acetoacetic Ester, CH 3 . CO . C :N(OH)CO 2 - C 2 H 5 , melting at 53, results when nitrous acid acts upon acetoacetic ester and aceto- malonic ester (B. 20, 1327). For an isomeric isonitroso-acetoacetic ester, see B. 28, 2676 ; 29, R. 997. u/3-Di-isonitroso- or Dioximido-butyric Ester, CH 3 . C : N- (OH). C;N(OH)CO 2 C 2 H 5 , decomposes at 152. It results from the action of NH 2 OH upon isonitroso acetoacetic ester (B. 25, 2552). The free acid, known in two modifications, forms, with hydrochloric acid, a lactone-like anhydride Oximido- CH 3 .C.C:N(OH).CO methyl-isoxazolon, II I , decomposing at 132. N.O.O.N Peroxid-di-isonitrosobutyric Acid, II II , melting at 92, is iw/OgV^ ' V_/ . V^/vJolJ. produced when silver di-isonitrosobutyrate is oxidized with nitric acid (B. 28, 2683). C 6 H 5 . NH . N : C . CO 2 C 2 H 5 Phenylhydrazone-acetyl-glyoxylic Ester, I , melt- CO . CH 3 ing at 154, is produced by the interaction of sodium acetoacetic ester and diazo- C 6 H..NH.N:C.CO 2 H benzene salts. Osazone-acetyl-glyoxylic Acid, I , melt- CgH 5 NH . N ; C . CH 3 ing at 209, is obtained from phenylhydrazone-acetyl-glyoxylic acid and phenyl- hydrazine in alcoholic solution (A. 247, 205). /3y-Diketo- or /3y-Dioxy-valeric Acid, CH 3 . CO . CO . CH 2 . CO 2 H. /Msonitroso kevulinic Acid, CH 3 CO . C : N- (OH) . CH 2 . CO 2 H, may be referred to this acid, unknown in a free condition. It is obtained from acetosuccinic ester. It melts at 119, decomposing into CO 2 and methyl-/3-oximidoethyl ketone (p. 326). Stearoxylic Acid and Behenoxylic Acid, already described (p. 288), are a-diketone carboxylic acids. Acetyl Pyroracemic Acid Ester, Acetone Oxalic Ester, ay-diketo- or ay-dioxovaleri- anic ester, CH 3 . CO . CH 2 . CO . CO 2 C 2 H 5 , results from the action of sodium ethylate upon acetone and oxalic ester. Ferric chloride imparts a dark red color to it. The free acid condenses to sym. oxytoluic acid, CO 2 H [i] C 6 H 3 [3.5](OH)CH 3 (B. 22, 3271). Acetone oxalic ester and phenylhydrazine yield a phenylpyrazole carboxylic ester, melting at 133 (A. 278, 278). The hydrogen in the acetoacetic esters can also be replaced by acid radicals. This is accomplished by acting upon the dry sodium compounds (suspended in ether) with acid chlorides. The products are diketone-monocarboxylic esters. Thus acetyl chloride (B. 17, R. 604) produces: Acetyl Acetoacetic Ester, C 2 H 3 O . CH(C 2 H 3 O) . CO 2 . C 2 H 5 , or Diaceto- acetic Ester, boiling at 122-124 (50 mm.). Its ester is produced when alcohol acts upon the product obtained from A1C1 3 and acetyl chloride (CH 3 CO) 2 CH. CC1 2 OA1- CI 2 (p. 323) (Gustavson, B. 21, R. 252). It is broken up by water, even at ordinary temperatures, into acetic acid and acetoacetic ester. Sodium ethylate displaces an acetyl group in it, forming acetoacetic ester and sodium acetoacetic ester. Methyl diaeetoacetic ester and ethyl diacetoacetic ester are only volatile without decomposition under diminished pressure. Acetonyl Acetoacetic Ester, CH 3 . CO. CH 2 . CHCCH 5 ' is produced by the action of chloracetone. CH 3 . CO . CH 2 C1, upon acetoacetic ester. It forms pyro- OXYMALONIC ACID GROUP. 485 tritaric ester (B. 17, 2759) with fuming hydrochloric acid. On heating the ester with water to 160 C., acetonyl acetone results (p. 323). /^TT Unsaturated Diketone Carboxylic ^^^^^-Mesityloxidoxalic Acid,^?^>0,^= CH . CO. CH 2 . CO.CO 2 H, melts with decomposition at 166. Caustic potash liberates it from either its ethyl ether, melting at 59 and boiling at 143 (ll mm.), or its methyl ether, melting at 67. On allowing sodium in ether to act upon molec- ular quantities of mesityl oxide and oxalic ester, then acidulating with dilute sul- phuric acid and distilling, a mixture of a- and /3-mesityloxidoxalic esters results. It can be separated by means of a sodium carbonate solution, in which the a-ether alone is soluble. Ferric chloride turns this a blood red. a-Mesityhxidoxalic Add, J 3 >C = CH . CO . CH = C(OH)CO 2 H, melting at 92, is obtained by the action of aqueous potash on its ethyl ether, melting at 21, or its methyl ether, melting at 83 (A. 291, ill, 137). 12. MONOXYDICARBOXYLIC ACIDS. A. MONOXYPARAFFIN DICARBOXYLIC ACIDS, CnH 2 n-i(OH)(CO 2 H) 2 . Numerous saturated monocarboxylic acids are known : thus, the oxymalonic acid group corresponds to the malonic acid group, oxy- succinic acid group to the ethyl succinic acid group, oxyglutaric acid group to the glutaric acid group, etc. It may be mentioned here that there are many representatives of these acids in which the hydroxyl group occupies the ^-position with reference to the carboxyl group, and these acids, when separated from their salts, readily part with water and become lactones. In general, the alcoholic hydroxyl group is introduced into the dibasic acids, just as it is done in the case of the monobasic acids. The reaction leading to the alkylized paraconic acids (p. 492) i-s worthy of mention. It is a condensation reaction between aldehydes and succinic acid or mono- alkylic succinic acids (p. 444). OXYMALONIC ACID GROUP. Tartronic Acid, CH(OH)<**, Oxymalonic Acid {Propanol- diacid~\, is produced : (i) From glycerol by oxidation with potassium permanganate ; (2) from chlor- and brom-malonic acid by the action of silver oxide or by saponifying their esters with alkalies; (3) from trichlorlactic acid when the latter is digested with alkalies (B. 18, 754, 2852); (4) from dibrompyroracemic acid when digested with baryta water; (5) from mesoxalic acid by the action of sodium amalgam. (6) Nucleus synthesis : from glyoxylic acid by the action of CNH and hydrochloric acid, and by the spontaneous decomposition of nitro- tartaric acid and dioxytartaric acid. Its formation from nitro-tartaric acid, described in 1854 by Des- saignes, has given it the name tartronic acid. 486 ORGANIC CHEMISTRY. Tartronic acid is easily soluble in water, alcohol, and ether, and crystallizes in large prisms. When pure, it melts at 184, decomposing into carbon dioxide and polyglycollide, (C 2 H 2 O 2 )x (B. 18, 756). The calcium salt, C 3 H 2 O 3 Ca, and barium salt, C 3 H 2 O 5 Ba -f 2H 2 O, dissolve with difficulty in water, and are obtained as crystalline pre- cipitates. The ethyl ester, C 3 H 2 O 5 (C 2 H 5 ) 2 (see above), is a liquid boil- ing at 222-225. The acetate, CH 3 CO . OCH(CO 2 C 2 H 5 ) 2) boils at 158-163 (60 mm.) (B. 24, 2997). Nitromalonic Ester, NO 2 . CH(CO 2 C 2 H 5 ) 2 , is an oil (B. 23, R. 62). Dimethyl ni- tromalonamide, NO 2 CH(CONHCH 3 ) 2 , melts at 156 (B. 28, R. 912). Fulniinuric acid is also a derivative of nitromalonic acid (p. 238). Amidomalonic Acid, NH 2 . CH(CO 2 H) 2 , consists of glistening prisms. It results from the reduction of oximidomalonic acid (see this). When its aqueous solution is heated, this body breaks down into GO 2 and glycin (p. 354). Its amide, NH 2 OH- (CONH 2 ) 2 , warty crystals, is formed when alcoholic ammonia at 130 acts upon chlormalonic ester. Imidomalonylamide, NH[CH(CONH 2 ) 2 ]. 2 (B. 15, 607) is produced at the same time. Its nitrile, NH 2 CH(CN) 2 , is a polymeride of prussic acid (p. 230). Alkylic Tartronic Acids. Methyl Tartronic Acid, Isomalic Acid, o-oxyisosuc- cinic acid, CH 3 C(OH)(CO 2 H) 2 , is obtained (l) by the action of silver oxide upon bromisosuccinic acid; (2) when prussic acid acts upon pyroracemic acid; (3) from diacetyl cyanide (p. 370) by the action of fuming hydrochloric acid (B. 26, R. 7 ; 27, R. 510). The acid breaks down into CO 2 and lactic acid when it is heated to 140. Ethyl l^artronic Acid, C 2 H 5 C(OH)(CO 2 H) 2 , is formed (l) on boiling ethyl chlor- malonic ester with baryta water (p. 442); (2) from dipropionyl cyanide (p. 371) ; (3) by the action of ethyl iodide upon sodium acetartronic ester (B. 24, 2999). It melts at 98, and when heated higher breaks down into CO 2 and a-oxybutyric acid. Propyl Tartronic Acid, CH 3 . CH 2 . CH 2 . C(OH) . (CO 2 H) 2 -f H 2 O, melts at 52- 56, and Isopropyl Tartronic Acid decomposes at 149. They are formed by the saponification of dibutyryl and diisobutyryl dicyanide (p. 371). a-Amidoisosuccinic Acid, CH 3 . C(NH 2 )^COOH) 2 , results when pyroracemic acid is acted upon with CNH and alcoholic ammonia (B. 20, R. 507). fi-Oxyisosuccinic Acid, CH 2 OH . CH (CO 2 H ) 2 . Its ethyl ether, C 2 H 5 OCH 2 . CH- (CO 2 H) 2 , has been obtained from methylene malonic ester (p. 456) by the action of alcoholic potash (B. 23, R. 194). y-Oxyalkylic Malonic Acids. The following y-oxymalonic acids are only known in the form of alkali or alkaline earth salts. These are produced when the corresponding y-lactone carboxylic acids are treated with caustic alkalies or the hydrates of the alkaline earths. The y-lactonic acids can easily be got from these salts ; these salts are produced by treatment with carbonates. CH 2 . CH 2 . CH.CO 2 H Butyrolactone-a-Carboxyhc Acid, \ \ , is prepared from brom- ethyl malonic acid, BrCH 2 . CH 2 . CH(CO 2 H) 2 , melting at 1 17. This is the hydro- bromide addition product of vinaconic acid, the trimethylene-l-dicarboxylic acid, when it is heated with water ; also on digesting the latter with dilute sulphuric acid (A. 227, 13). Heated to 120, butyrolactone carboxylic acid breaks down into CO 2 and butyrolactone (p. 345). The phenyl ether of oxyethyltartronic acid, C 6 H 5 O.- CH 2 . CH 2 . CH melts at I42 o (B 2g> R 286) CH 2 . CH 2 . C(CH 3 )CO 2 H a-Methylbutyrolactone-a-carboxylic Acid, \ i, ' , melting at 98, results when brom ethyl isosuccinic ester, the reaction product of ethylene bromide and sodium isosuccinic ester, is treated with baryta water and then acidulated (A. 294,89). OXYSUCCINIC ACID GROUP. 487 a-Carbovalerolactonc Carboxytic Acid, y-Methylbutyrolactone-a-carboxylic Acid, CH..CH. CH 2 . CHCOJi i i ' , results when allyl malonic acid is acted upon with HBr. It breaks down at 200 into CO 2 and y-valerolactone (p. 345). OXYSUCCINIC ACID GROUP. Malic Acid, Oxyethylene Succinic Acid(Acidum malicuni), \_Butanol- HO.*CH. CO 2 H diacid\ \ _ ... Malic acid contains an asymmetric carbon CH 2 .CO 2 H atom; it can occur in three modifications: (i) a dextro-rotatory form, (2) a laevo-rotatory form, and (3) an inactive [d -j- 1] variety. This is a compound of equal molecules of the dextro- and laevo-rotatory modifications. The Isevo-variety occurs free or in the form of salts in many plant juices, hence it is frequently spoken of as ordinary malic acid. It is found free in. unripe apples, in grapes, and in gooseberries, also in mountain -ash berries (Sorbus aucuparia) and in Berberis vulgaris. It is obtained from the last two sources by means of the calcium salts (A. 38, 257; B. 3, 966). Acid potassium malate is contained in the leaves and stalks of rhubarb. Historical. Ordinary malic acid was discovered in 1785 by Scheele in unripe gooseberries. Liebig ascertained its composition in 1832. Pasteur, in 1852, ob- tained inactive malic acid from inactive aspartic acid, and Kekule (1861) made it from bromsuccinic acid. The dextro-acid was first obtained by Bremer in the reduc- tion of dextro-tartaric acid. Formation of Optically Inactive or [d -j- 1] Malic Acid, melting at 130 (B. 29, 1698) : 1. From the mono-ammonium salt of Isevo-, and dextromalic acid. 2. By heating fumaric acid to 150200 with water. 3. When fumaric or maleic acid is heated with caustic soda to 100 (B. 18, 2713). 4. By treating monobromsuccinic acid with silver oxide and water, with water alone, with dilute hydrochloric acid, or with dilute sodium hydroxide at 100 (B. 24, R. 970). 5. By the action of N 2 O 3 upon inactive aspartic acid. 6. By the reduction of racemic acid with hydriodic acid. 7. When oxalacetic ester is reduced with sodium amalgam in acid solution (B. 24, 3417; 25, 2448). 8. By the action of caustic potash upon the transposition-product of CNK and /3-dichlorpropionic ester. 9. By saponifying the esters of chlorethane tricarboxylic acid. 10. When caustic potash acts upon y-trichlor-/?-oxybutyric acid, CC1 3 CH . OH . - CH 2 . CO 2 H, the reaction-product of glacial acetic acid with chloral and malonic acid (B. 25, 794). The identity of the acids from I to 6 has been proved by means of the well-crystal- lized mono-ammonium salt, C 4 H 5 O 5 NH 4 -\- H 2 O, of the inactive acid (B. 18, 1949, 2170). Formation of the l&vo- and dextro- forms : Racemic acid can be reduced to inactive malic acid, which cinchonine will resolve into salts of the two acids (B. 13, 351 ; 18, R. 537). The dextro-acid has also been obtained by the reduction of ordinary or dextro-tartaric ORGANIC CHEMISTRY. acid with hydriodic acid, and by the action of nitrous acid upon dextro-aspartic acid, whereas 1-asparagine and 1-aspartic acid yield ordinary or 1-malic acid (B. 28, 2772). To convert the two optically active malic acids into each other it is only necessary to treat the chlorsuccinic acids, obtained from them, with moist silver oxide (Walden, B. 29, 133). Properties. Malic acid forms deliquescent crystals, which dissolve readily in alcohol, slightly in ether, and melt at 100. Deportment. Natural malic acid shows the following reactions: (i) When heated for some time to 140-150, the principal product is fumaric acid ; heated rapidly to 180, it decomposes into water, fumaric acid, and malei'c anhydride (p. 459). (2) Succinic acid is formed by the reduction of malic acid. This is accomplished by the fermenta- tion of the lime salt with yeast, or by heating the acid with hydriodic acid to 130 (p. 443). (3) When it is warmed with hydrobromic acid, it forms monobrom-succinic acid. PCI 5 at the ordinary tem- perature converts 1-malic acid into d-chlorsuccinic acid, which moist silver oxide changes to d-malic acid. (4) Coumalic acid (p. 496) is produced when malic acid is heated alone or with sulphuric acid or zinc chloride. (5) The coumarines are produced when the acid is heated with phenols and sulphuric acid. This result is probably to be explained by assuming that the malic acid first changes to the half- aldehyde of malonic acid, CHO . CH 2 . CO 2 H, and this then con- denses with the phenols (B. 17, 1646). Salts of the. Inactive Acid : Mono-ammonium malate, C 4 H 5 O 5 NH 4 -f- H 2 O (B. 18, 1949, 2170). The diethyl ester, C 2 H 3 (OHXCO 2 C 2 H 5 ) 2 , boils at 255 (B. 25, 2448). Salts of the lavo-acid, malates : The primary ammonium salt, C 4 H 5 (NH 4 )O 5 , when exposed to a temperature of 160-200, becomes fttmarimia'e, C 4 H 2 O 2 . NH (A. 239, 159 Anm.). Neutral Calcium Malate, C 4 H 4 O 5 Ca -|- H 2 O, separates as.a crystalline powder on boiling. The acid salt, (C 4 H 5 O 5 ) 2 Ca -f-6H 2 O, forms large crystals which are not very soluble in cold water (B. 19, R. 679). Sodium Brommalate (from the acid, C 4 H.BrO.) is formed when the aqueous solution of sodium dibromsuccinate is boiled ; milk of lime transforms it into tartaric acid. \-Malic Ethers and Esters : The dialkylic esters when slowly heated pass into fumaric esters (B. 18, 1952), while PC1 5 and PBr 5 changes them, in chloroform, to d-chlor- and d-brom-succinic esters (p. 451). The optical rotatory power of some of these esters has been determined. They are laevorotatory (B. 28, R. 725 ; 29, R. 164, C. 1897, I, 88) : 1-Malic Methyl Ester boils 122 (12 mm.); a 1-Malic Ethyl Ester " 129 (12 mm.) ; a 1-Malic-n-propyl Ester " 150 (12 mm.) ; a 1-Malic-n-butyl Ester " 170 (12 mm.); a D] == 6.883, M n] = 10.645, M n] = 11.601, M D] = 10.722, M D] -= 11.15 r>l = 20.22 D] = 25.29 D] =26.38 Triethyl Ester, C.,H^O . C 2 H,(CO a C 8 H0 2 , boilsat 118-120 (15 mm.) (B. 13, 1394). Acctyl Malic Acid, CH 3 CO. OC 2 H,(CO 2 H) ? . melts at 132. Acttyl Malic Dimethyl Ester, CH 3 CO . OC 2 H 3 (CO 2 CH 3 ) 2 , 'when carefully dis- tilled at the ordinary temperature, yields fumaric dimethyl ester. Acetyl Malic Anhy- AMIDO-SUCCINIC ACIDS. 489 dridt, CH 3 . CO . OC ? H 3 (C. 2 O 3 ), melting at 53-54 and boiling at 160-162 (14 mm.), decomposes when distilled at the ordinary temperature into maleic anhydride and acetic acid (A. 254, 166). Acetyl-1-malic methyl ester boils at 132 (12 mm.) ; a[o] 22.864, ^/[D] = 46.64. Acetyl-1-malic ethyl ester boils at 141 (12 mm.) ; a[n] = 22.601, yJ/[o] = 52.43- Propionyl-1-malic methyl ester boils at 142 (12 mm.) ; [D] = 23.08, J/[D] = (~"O "NTT-T Amides of Lavo-malic Acid: Ethyl Malamate, C 2 H 3 (OH)<^ ' ^-fa , is ob- tained by leading ammonia into the alcoholic solution of malic ester ; it forms a crys- talline mass. Malamide, C 4 H 8 O 3 N 2 , is formed by the action of ammonia upon dry ethyl malate. Sitlphosuccinic Acid, (SO 3 H)C 2 H 3 (CO 2 H) 2 . \-Chlormalic Ethyl Ester, melting at 162-165 ( X 5 mm.), and \-brommalic ethyl ester, boiling at 165-168 (15 mm.), are produced when PC1 5 and PBr 5 act upon d-tartaric acid (B. 28, 1291). AMIDO-SUCCINIC ACIDS. Aspartic acid bears the same relation to malic and succinic acids as glycocoll bears to glycollic acid and acetic acid ; hence, it may be called amido-succinic acid : NH 2 . CH 2 CO 2 H HO . CH 2 . CO 2 H CH 3 . CO 2 H Glycocoll Glycollic Acid Acetic Acid NH 2 . CH . CO 2 H HO . CH . CO 2 H CH 2 . CO 2 H CH, . C0 2 H CH, . C0 2 H CH 2 . CO 2 H Amidosuccinic Acid Malic Acid Succinic Acid. Amidosuccinic acid contains an asymmetric carbon atom. Like malic acid, it can appear in three modifications. The 1-amido-suc- cinic acid or laevo-aspartic acid is the most important of these. Inactive [d -f 1] Aspartic Acid, Asparacemic Acid, NH 2 C 2 H 3 (CO 2 H) 2 , is produced : (I) By the union of 1- and d-aspartic acids. ( 2 j On heating active aspartic acid (a] with water, (b) with alcoholic ammonia to 140-150, or (c) with hydrochloric acid to 170-180 (B. 19, 1694). (3) When fumarimide (p. 488) is boiled with hydrochloric acid. (4) On heating fumaric and maleic acids with ammonia (B. 20, R. 557; 21, R. 644). (5) By evaporating a solution of hydroxylamine fumarate (B. 29, 1478). (6) By reducing oximido-succinic ester with sodium amalgam (B. 21, R. 351). Like glycocoll, it combines with alkalies and acids yielding salts. Nitrous acid changes it to inactive malic acid. [A + \]-Dietkyl Aspartic Ester, NH 2 . C 2 H 3 (CO. 2 C 2 H 5 ) 3 , boiling at 150-154 (25 mm.), is produced on heating fumaric and maleic esters with alcoholic ammonia (B. 21, R. 86). fTT f O C* T-T Ethyl a- Aspartic Ester, NH 2 . i 5 , melting at 165 (decomposition), is CH 2 . CO. 2 H formed by the reduction of a-oximido-succinic monethyl ester and the diethyl ox- imido-oxalacetic e^ter. Ammonia converts it into inactive a-asparagine (constitution, compare p. 491). 49 ORGANIC CHEMISTRY. C* T-T C*C\ C* TT Ethyl ft- Aspartic Ester, i 2 ' ' , melts with decomposition at JN li 2 v-'O. . VvvJo^l about 200, and is also obtained from the oxime of oxalacetic ester by reduction with sodium amalgam. A partial saponification occurs at the same time. Ammonia converts it into the two optically active asfiaragines, which are therefore /3-amido- succinamic acids. NH 2 . CH . CONH 2 [d -f 1] a-Asparagine, i , decomposes at 213-215 without CH 2 . CO 2 H melting, and results from asparaginimide, aspartic diethyl ester, and a-aspartic mon- ethyl ester on treating them with concentrated ammonia. NH 2 . CH . CO Asparaginimide, i _ ^>NH (?), consists of needles, which char at CH 2 . CO about 250. It is produced when ammonia (B. 21, R. 87) acts upon bromsuccinic ester. Phenylaspartic Acid, C 6 H 5 NH . CH(CO 2 H)CH 2 . CO 2 H, melting at 131, is formed from the action of bromsuccinic acid upon aniline. Phenylasparaginanil ', C 6 H 5 NHC 2 H 3 C 2 O 2 . NC 6 H 5 , melts at 210. It results on adding aniline to'malem- anil (A. 239, 137). CH(NH 2 ) . CO 2 H 1-Aspartic Acid, i TT ' , occurs in the vmasse obtained CH 2 . CO 2 H from the beet root, and is procured from albuminous bodies in various reactions. It is prepared by boiling asparagine with alkalies and acids (B. 17, 2929). Naturally occurring aspartic acid is laevo-rotatory ; it crystallizes in rhombic prisms or leaflets, and dissolves with difficulty in water. Nitrous acid converts it into ordi- nary 1-malic acid (B. 28, 2769). ^-Aspartic Acid is produced when d-asparagine is boiled with dilute hydrochloric acid (B. 19, 1694). CH 2 . CONH 2 1- and d- Asparagine, NH ^ Hco H + H 2> are the monam- ides of the two optically active aspartic acids, and are isomeric with malamide. Historical. As early as 1805 Vauquelin and Robiquet discovered the laevo-aspara- gine in asparagus. Liebig, in 1833, established its true composition. Kolbe (1862) was the first to regard it as the amide of amidosuccinic acid. Piutti (1886) discov- ered dextro-asparagine in the sprouts of vetches, in which it occurs together with much laevo-asparagine. Lsevo-asparagine is found in many plants, chiefly in their seeds; in asparagus {Asparagus officinalis], in beet-root, in peas, in beans, and in vetch sprouts, from which it is obtained on a large scale, and also in wheat. The laevo- and dextro-asparagines not only occur together in the sprouts of vetches, but they are found together if asparaginimide, produced from bromsuccinic ester, is heated to 100 with ammonia, or by the action of alcoholic ammonia upon /9-aspartic ester (B. 20, R. 510; B. 22, R. 243). Dextro-asparagine, from the sprouts of vetches, has been produced on heating male'ic anhydride to 110 with alcoholic ammonia (B. 29, 2070). CONSTITUTION OF THE ASPARAGINES. 49! Both optically active asparagines crystallize in rhombic, right and left hemihedral crystals, which dissolve slowly in hot water, in alcohol and ether, but they are not easily soluble. It is not possible for them to combine in aqueous solution to an optically inactive asparagine. It is remarkable that the dextro-asparagine has a sweet taste, while the laevo-form possesses a disagreeable and cooling taste. Pasteur assumes that the nerve substance dealing with taste behaves toward the two asparagines like an optically active body, and hence reacts differently with each. Constitution of the Asparagines. When the oxime of oxalacetic ester is reduced with sodium amalgam, either a- or /3-ethyl-amido-succinic acid is formed with a par- tial saponification, depending upon the conditions of the reaction. The constitution of the a acid, melting at 165, follows from its formation by the reduction of the two probable, spacial isomeric oximidosuccinic ethyl ester acids, which split off CO 2 and yield a-oximidopropionic acid (p. 371). Hence, it may be inferred that the acid melting with decomposition at 200 contains the amido group in the /3-position with reference to the carboxethyl group (B. 22, R. 241). Ammonia converts both acids into their corresponding amido-acids. We obtain inactive a-asparagine from the a-acid, and from the /3-acid a mixture of the two optically active /3-asparagines results: | ' C=NOH iH, \ C0 2 C 2 H 5 CONH 2 C0 2 . C 2 H 5 CHNH 2 - > CHNH, i N(OH) CH 3 CH 2 iH, I I i CO 2 H CO 2 H CO 2 H m. p. 165 Inact.-a-Aspara- Ethyl Oximido- gine succinic Acid CO 2 H CO 2 H (W T H 2 CHNH 2 CH 2 >- 1 C0 2 C 2 H. CONH 2 ' m. p. 200 L4-D /3-Asparagine. C0 2 C 2 H 5 ^C^N(OH) a-Oximido-pro- pionic Ester fTT (~*f\ TT Isoasparagine, . I results from the action of aluminium amalgam NH 2 CH . CONH 2 upon potassium amidofumaramidate (C. 1897, I, 364). Malic Acid Homologues are formed : by the addition of hydrocyanic acid to /3-ketonic esters ; by the addition of C1OH to alkylic malelc acids and subsequent reduction ; and by the reduction of alkylic oxalacetic esters. CH 3 C(OH)CO 2 H a-Oxypyrotartaric Acid, Citramalic Acid, a-Methyl Malic Acid, ^ CH 2 . CO 2 H melting at 119, is produced (l) in the oxidation of isovaleric acid (p. 248) with nitric acid ; (2) from acetoacetic ester by means of CNH and HC1, and (3) by the reduction of chlorcitramalic acid, the addition product resulting from the union of C1OH to citraconic acid. It breaks down at about 200 into water and citraconic anhydride (B. 25, 196). fi-Aniidopyrotartaric Acid, [d -{- 1] homoaspartic acid, 1 i, * 2 -f H 2 O, melts when anhydrous at 166. Its diamide results CH 2 CO 2 H 492 ORGANIC CHEMISTRY. from the action of ammonia upon ita-, citra-, and rnesaconic esters (13. 27, R. 121). When it crystallizes it splits into the d- and 1-acids. CH S .C(NHC 6 H 5 )CO,H p-Amhdopyrotartanc Acid, \ ' , melting at 135, results CH 2 . CO 2 H from the rearrangement of the HCN-addition product of acetoacetic ester with aniline, and the subsequent saponification with caustic potash. When heated, it passes into /3-anilidopyrotartranil and citraconanil (A. 261, 138). CH 3 . CH . C0 2 H $- Methyl Malic Acid, ' L R / OT TX ro > is a colorless syrup, readily solu- ble in water, in alcohol, and in ether. It is formed when methyl oxalacetic ester is reduced with sodium amalgam, and in an active 1- form from a citraconic acid solu- tion by the action of a fungus (B. 27, R. 470). Mesaconic acid and citraconic anhy- dride (B. 25, 196, 1484) are produced when it is heated. a,$-Methyl Ethyl Malic Acid, \( " * , melts at 131.5-132 (B. 26, (^2 H - \^ n. (^ \J:],n. R. 190). Trimethyl Malic Acid melts at 155 (lO sec. 1), and is obtained from dimethyl acetoacetic ester with prussic acid, with subsequent saponification by hydrochloric acid (B. 29, 1543, 1619). (CH 3 ) 2 . CH . C(OH) . C0 2 H Isopropyl Malic Acid, i^ , from brom-pimelic ester (A. CH 2 . CO 2 H 267, 132), melts at 154. Paraconic Acids are y-lactonic acids. Like the y-oxyalkylic malonic acids, they are converted by alkalies and alkaline earths into salts of the corresponding oxy- succinic acids. When the latter are set free from their salts they immediately break down into water and lactonic acids. The alkylic paraconic acids are formed when sodium succinate or pyrotartrate and aldehydes (acetaldehyde, chloral, propionic aldehyde) are condensed by means of acetic anhydride at 100-120 (Fittig, A. 255, I): Succinic Acid Methyl Paraconic Acid. s*\ TT ^T-I.x^' 2 Paraconic Acid, i 2 ~ ^ CH 2 > is best prepared by boiling itabrom- - CO pyrotartaric acid with water and acidulating the calcium salt of the corresponding oxysuccinic acid itamalic acid, formed on boiling itachlorpyrotartaric acid with a soda solution. It melts at 57-58. When boiled with bases, it forms salts of itamalic acid; it yields citraconic anhydride when it is distilled (A. 216, 77). CH 2 . CH . C0 2 H Psendoitaconanilic Acid, y-anilidopyrotartro-lactamic acid, \ , C 6 H 5 N . CO . CH 2 melting at 190, is formed from itaconic acid (A. 254, 129), by the addition of ani- line, and the lactam formation. /"-TT pT-T _ CH CO H Methyl Paraconic Acid, 3 1 I ' , melts at 84.5. When dis- tilled, methyl paraconic acid yields valerolactone, ethidene propionic acid (p. 283), methylitaconic acid, and methyl citraconic acid (B. 23, R. 91). Trichlor methyl Paraconic Acid, 3< i I " 2 , melting at 97, is changed O . CO . CH 2 by cold baryta water into isocitric acid (see this). OXYGLUTARIC ACID GROUP. 493 Ethyl Paraconic Acid, ^CH 2 , melts at 85 C. When distilled, 6 CO it breaks up chiefly into carbon dioxide and caprolactone (p. 346). Isomeric hydro- sorbic acid is formed at the same time (B. 23, R. 93). (CH 3 ) 2 C - CHCO 2 H Terebic Acid, v J; i i , Terpenylic Acid, O . CO . CH 2 (CH 3 ) 2 C CH . CH 2 . CO 2 H 6 CO CH 2 (CH 3 ) a C - CH . CH, . CH 2 . CO 2 H and Homoterpenylic Acid, I I , are three oxidation O . CO . CH 2 products of turpentine oil. They will be discussed in connection with pinene, the principal ingredient of the oil. C 3 H 7 . CH . CH<2 H Propylparaconic Acid, | ^"2 , melts at 73.5. y-Heptolac- O - CO tone, heptylenic acid, C 7 H 12 O 2 , and propylitaconic acid, C 8 H 12 O 4 (B. 20, 3180), are produced by the distillation of propylparaconic acid. Isopropylparaconic Acid melts at 69, and when distilled decomposes into }-isoheptolactone and isoheptylenic acid. OXYGLUTARIC ACID GROUP. c Oxyglutaric Acid, CH,< ^* (A. 208, 66, and B. 15, 1157), is obtained by the action of nitrous acid upon glutaminic acid ; it occurs in molasses. It crystallizes with difficulty, and melts at 72. Heated with hydriodic acid, it yields glutaric acid (p. 452). When heated, it readily passes into its lactone, melting at 49-50 (A. 260, 129). Glutaminic Acid, a-Amidoglutaric Acid, CH 2

rr /-< (""(") II Aconic Acid, i i ! , melting at 164, which results on boiling ita- O . CO . CH 2 dibromtartaric acid with water (A. Spl. 1,347 ; B. 27,3440). The methyl ester melts at 84. Aconic acid bears the same relation to ethoxymethylene succinic ester that coumalic acid sustains to methyl methoxymethylene glutaconic ester. CH, . C = C . CO 2 C,H S c-Aminoethidene Succinic Ester, i i , melts at 72 (B. NH 2 . CH 2 . CO 2 C 2 H 5 20, 3058) and a-Aminoethidene Succinimide melts at 274. See acetosuccinic ester. (""tr r* (~]J-T P(~) IT MucolactonicAcid, i i 2 , is obtained by heating dibromadipic \J V^\-/ - X^llo acid, C 6 H 8 Br 2 O 4 (from hydromuconic acid, p. 467), with silver oxide. It melts at 122-125. 49^ ORGANIC CHEMISTRY. /3-Amidoglutaconic Ester, CO 2 C 2 H 3 . CH = C(NH 2 )CH 2 . CO 2 C 2 H 5 , boils at /CH . CO 157-158 (12 mm.). Glutazine, /3-amidoglutaconimide, NH 2 . C^ ^NH, X CH 2 . CCK melts with decomposition at 300 (compare acetone dicarboxylic ester). Lactams of y-amido unsaturated dicarboxylic acids result when ammonia and primary amines act upon acetoacetic ester (A. 260, 137) : CH 3 .CO . CH.CO 2 C 2 H 5 CH 3 .C = C.CO 2 C 2 H 5 CH 3 .C - C.CO 2 C 3 H 5 .CO.CH 2 ~ ^ NH. Lactams of d-amido unsaturated dicarboxylic acids are formed when ammonia and primary amines act upon a-acetylglutaric ester (B. 24, R. 661). C. OXYDIOLEFINE DICARBOXYLIC ACID. CH C . CO,H Coumalic Acid, i i > melts with decomposition at 206. O . CO . CH = CH It is isomeric with comanic acid (see this). It is produced when malic acid is heated with concentrated sulphuric acid or ZnCl 2 . Oxymethylene acetic acid, HO . CH = CH . CO 2 H (p. 361), is an intermediate product. Its condensation gives rise to the coumalic acid, since the latter is also formed when sulphuric acid acts upon oxy- methylene acetic ester (A. 264, 269). Like chelidonic and meconic acids, it forms yellow-colored salts with the alkalies. Coumalic acid is decomposed by boiling baryta water into glutaconic acid (p. 467) and formic acid. Boiling dilute sulphuric acid breaks it down into CO 2 and crotonaldehyde (p. 208). Ammonia converts it into the corresponding fi-lactam, the so-called B-oxynicotinic acid. It combines to CH.CH 2 pyrazolon, II . >CO (p. 367) (B. 27, 791), with a dilute hydrazifie solution. Oxymethylene Glutaconic Acid, HO . CH = C(CO 2 H) . CH = CH . CO 2 H. Coumalic acid might be regarded as the d-lactone of this oxy-acid. It is not known in a free state, but methoxymethylene ghttaconic methyl ester, CH 3 O . CH = C(CO 2 CH 3 ) . CH = CH . CO 2 CH 3 , melting at 62, is produced on treating coumalic acid with methyl alcohol and hydrochloric acid (A. 273, 164). C(CH 3 )=rrC. CO 2 H Isodehydracetic Acid, Dimethyl Coumalic Acid, i L, > O . COCH C.CH 3 melting at 155, is isomeric with dehydracetic acid (see this). It is produced (i) by the action of concentrated sulphuric acid upon acetoacetic ester; (2) from /3-chloriso- crotonic ester and sodium acetoacetic ester (A. 259, 179). It decomposes when heated to 200-205 i nt CO 2 and mesitene lactone. The methyl ester melts at 67-67 5 and boils at 167 (14 mm.). The ethyl ester boils at 166 (12 mm.). The latter takes up ammonia and yields an ammonium salt, which in a certain respect is simi- larly constituted to ammonium carbamate, T^TT* ^>C = O : IN rig O.C(CH 3 ) = C.C0 2 C 2 H 5 NH 2 ' 3 fi-Oxynicotinic Acid and /3-oxy-dimethyl nicotinic acid are cJ-lactams correspond- ing to coumalic and isodehydracetic acids. The ethyl ester of the second lactam the so-called carboxethyl pseudolutidostyril, melting at 137 results from the action of ammonia upon ethyl isodehydracetic ester at 100-140. The same cMac- tam is obtained in the condensation of /3-amidocrotonic ester (p. 363) (A. 259, I7 2 )- KETOMALONIC ACID GROUP. 497 13. KETONE DICARBOXYLIC ACIDS. Dibasic carboxylic acids, containing a ketone group in addition to the carboxyl groups, are mainly synthesized as follows : 1. By the introduction of acid radicals into malonic esters. 2. By introducing the residues of acid esters into acetoacetic ester. 3. By the condensation of oxalic esters with fatty acid esters. These methods of formation will be more fully considered under the individual groups of the monoketone carboxylic acids. The position of the two carboxyl groups is again the basis for their classification as the ketomalonic acid group, the ketosuc citric acid group, the ketoglutaric acid group, etc. KETOMALONIC ACID GROUP. Mesoxalic Acid, Dioxymalonic Acid, \Propandiol-diacid~\, melts at 115 without loss of water. It is assumed that in this acid as in glyoxylic acid, and oxalic acid crystallized from water, the water molecule is not present as water of crystallization, but that the double union between the carbon and oxygen has been severed, and that it has attached itself to the CO-group, hence two hydroxyl groups are produced, whence the name dioxymalonic acid : C0 2 H H0 \r nw H0 \rw HC O HQ >C-OH HCK^ 1 * H0 >( j HQ>C OH COOH C0 2 H Ortho-oxalic Acid Glyoxylic Acid Mesoxalic Acid. Furthermore, esters of mesoxalic acid derived from both forms are known. They are the oxo- and the dioxymalonic acid esters. Mesoxalic acid is formed from amidomalonic acid by oxidation with iodine in an aqueous solution of potassium iodide; from dibrom-malonic acid by boiling with baryta water or silver oxide ; by boiling alloxan (mesox- alyl urea) with baryta water ; and by oxidizing glycerol with nitric acid, nitre, and bismuth subnitrate (B. 27, R. 666). Mesoxalic acid crystallizes in deliquescent prisms. At higher tem- peratures it decomposes intoCO 2 and glyoxylic acid, CHO . CO 2 H. It breaks up into CO and oxalic acid by the evaporation of its aqueous solution. Mesoxalic acid deports itself like a ketonic acid, inasmuch as it unites with primary alkaline sulphites, and when acted upon by sodium amalgam in aqueous solution, it is changed to tartronic acid. It combines with hydroxylamine and phenylhydrazine. 42 49^ ORGANIC CHEMISTRY. Salts. Barium mesoxalate, C(OH) 2 <^pQ 2 >Ba, and calcium mesoxalate, are crys- talline powders, not very soluble in water. The ammonium salt, C(OH) 2 . (CO 2 .- NH 4 ) 2 , crystallizes in needles. The silver **//,C(OH) 2 . (CO 2 Ag) 2 , when boiled with water affords mesoxalic acid, silver oxalate, silver, and CO 2 . See B. 27, R. 667, for the bismuth salt. Esters. Two series of esters may be derived from mesoxalic acid the anhydrous or oxomalonic esters, CO(CO 2 R% and the di- oxymalonic esters, C(OH) 2 (CO 2 R') 2 . The first are produced when the reaction-product from bromine and acetotartronic ester is distilled, and also in the distillation of dioxymalonic ester under diminished pressure. The oxomalonic esters absorb water with avidity, and thereby change to their corresponding dioxymalonic esters. The two compounds bear the same relation to each other that chloral sustains to chloral hydrate : HoO CClg.CHO Chloral- >CC1 8 .CH(OH) 2 Chloral Hydrate CO(CO 2 C 2 H 5 ) Oxomalonic Ester ^-> C(OH),(CO 8 C a H 6 ) 2 Dioxymalonic Ester. Oxomalonic Ethyl Ester, CO(CO 2 C 2 H 5 ) 2 , boiling at 100-101 (14 mm.), sp. gr. 1.1358 (16), possesses a bright greenish-yellow color. It is a mobile liquid, with a faint but not disagreeable odor. When heated under ordinary pressure it breaks down partly into CO and oxalic ester (B. 27, 1305). Dioxymalonic Ethyl Ester, C(OH) 2 . (CO 2 C 2 H 5 ), melting at 57, dissolves easily in water, alcohol, and ether. Diethoxymalonic Ester, (C 2 H 5 O) 2 C(CO 2 C 2 H 5 ), melts at 43 and boils at 228 (B. 30, 490). Diacetdioxymalonic Ester, (CH 3 CO . O) 2 C(CO 2 C 2 H 5 ) 2 , melts at 145- Nitrogen Derivatives of Mesoxalic Acid. Isonitrosomalonic Acid, C(N . OH)(CO 2 H) 2 , is formed by the action of hy- droxylamine (B. 16, 608, 1621) upon violuric acid (see this) and mesoxalic acid, also from its ethyl ester, produced when nitrous acid is conducted into the solution of sodium malonic ester. It melts at 126, decomposing at the same time into hydro- cyanic acid, carbon dioxide, and water. Dimethyloximidomesoxalamide, N(OH) : - C(CONHCH 3 ) 2 , melts at 228 (B. 28, R. 912). Phenylhydrazidomesoxalic Acid, C 6 H 5 NH . N : C(CO 2 H) 2 , melts with decom- position at 163. It is obtained (l) from mesoxalic acid and phenylhydrazine ; (2) by the saponification of its ethyl ester. Ethyl Phenylhydrazidomesoxalic Acid, c 6 H 5 NH . N == c N . C 6 H 5 , melt- CH 3 . CH . CO' ing at 191-192, is formed from oxalic ester and propionanilide (B. 24, 1256). Ethyl Oxal- acetic Ester, CO 2 C 2 H 5 . CO.CH(C 2 H 5 )CO 2 C 2 H 5 (B. 20, 3394). Nitrogen Derivatives of Oxalacetic Acid (B. 24, 1198). Ammonia and oxal- acetic ester combine to a body which has one of the following formulas : CO 2 G,H 5 .- C(OH)NH 2 . CH 2 . CO 2 C 2 H 5 or CO 2 . C 2 H 5 . C(ONH 4 ) : CH . CO 2 C 2 H 5 (B. 28/788), see ethoxyfumaric acid, p. 495- Oxinies : fl-Oximidosttccinic Ethyl Ester, melting at 54, results from the oxime of oxalacetic ester. a-Oximidosuccinic Ethyl Ester Acid, melting at 107, is produced when water acts upon diisonitrososuccinyl succinic ester. Both bodies, when heated with water, yield CO 2 and a-oximidopropionic acid, CH 3 C: N(OH)CO 2 C 2 H 5 . Hence, both ester acids are given the structural formula, CO 2 H . CH 2 C : N(OH)CO 2 C 2 H 5 , and it is assumed that they are stereo-isomerides (B. 24, 1204). Oximidosuccinic Ester, CO 2 C ? H 5 . C : N(OH)CH 2 . CO 2 C 2 H 5 , is a colorless oil (B. 21, R. 351). Compare aspartic acid and asparagine, pp. 489, 490. Phenylhydrazine adds itself to oxalacetic ester just the same as ammonia. The addition product, melting at 105, is either a phenylammonium salt of oxyfumaric acid, or it is a compound similar to aldehyde ammonia. It readily passes into the phenylhydrazone-oxalacetic ester, C 6 H 5 NH . N : C<~2 2 2 5?A r , melting at 77. V^iln ^-'^225 The reaction products of hydrazine and phenylhydrazine upon oxalacetic ester are the lactazams (p. 363) or pyrazolon derivatives (A. 246, 320; B. 25, 3442), e.g. : CO . C0 2 C 2 H 5 N H 2 NH 2 NH . N = C . CO 2 C 2 H 6 CH 2 . C0 2 C 2 H 6 *" CO - - CH 2 Pyrazolon Carboxylic Ester. Phenylhydrazone-oxalacetic ester is also formed from acetylene dicarboxylic ester and phenylhydrazine (B. 26, 1721). Oximido-cyanpyroracemic Ester, CN . CH 2 . C = N(OH)CO 2 C 2 H 5 , melts at 104 (B. 26, R. 375). N O Ammonium Isoxazolonhydroxamate, NH.HO\ II I , decomposes at HONx^ c c CH 2 co 156-160. It is produced in the action of hydroxylamine and ammonia upon oxal- acetic ester. See also cyanoximidoacetic acid, p. 498. Alkali changes it to N : C . CH 2 . CO 2 H Oxyfurazan-acetic Acid, O<^ I , consisting of prisms, decompos- ing at 158. Potassium permanganate oxidizes it to oxyfurazan carboxylic acid (B. 28, 761). KETOGLUTARIC ACID GROUP. 50! Diazosuccinic Esters are formed when sodium nitrite acts upon the hydrochlo- rides of aspartic esters. The crude, yellow-colored, easily decomposable esters, when boiled with water, pass into fumaric esters. They revert to aspartic esters on reduc- tion. Methyl Diazosucdnamic Ester, CO 2 . CH ? . CN 2 . CH 2 .CONH 2 , melting at 84, is formed when ammonia acts upon methyl diazosuccinic ester (B. 19, 2460 ; 29, 763). Acetosuccinic esters and alkylic acetosuccinic esters are produced when sodium acetoacetic esters and their monoalkylic derivatives are acted upon by esters of the a-monohalogen fatty acids. CH 3 . CO . CH . CO 2 C 2 H 5 Aceto-succinic Ester, , is prepared from acetoacetic CH 2 . CO 2 C 2 H 5 _oA/^o TI, CO 2 C 2 H ester and chloracetic ester. It boils at 254-260. The hydrogen atom of the CH group, in the esters, can be replaced by alkyls, e.g., by methyl : CH 3 .CO.C(CH 3 ).C0 2 C 2 H 5 a-Methyl Aceto-succinic Ester, 5 , is formed from CH 2 .C0 2 C 2 H 5 methyl acetoacetic ester and chloracetic ester. It boils at 263. CH 3 .CO.CH.C0 2 C 2 H 5 (tH(CH 3 ).C0 2 C 2 H 5 V^J.J.Q . \_/\_x . V^AX . v^\_/ftVxoia - /3-Methyl Aceto-succinic Ester, i , from aceto- acetic ester and a-brom-propionic ester, boils at 263. By the acid decomposition these esters break down into acetic acid and succinic acid or alkylic succinic acids (pp. 443, 444) > ^7 ^ ne ketone decomposition the pro- ducts are CO. 2 and y-ketonic acids (p. 379). Ammonia and primary amines convert the acetosuccinic esters into y-amidodicarbonic acids, which readily part with alcohol and become y-lactams (A. 260, 137). Acetosuccinic ester and ammonia yield: a-amino-ethidene succinic ester (p. 495) and a-amino-ethidene succinimide. Hydro- C* I-T C^C\ C~* FT C*r\ chloric acid converts the latter into acetosucdnimide -, >NH, CH 2 .CO melting at 84-87 (C. 1897, I, 283). Nitrous acid converts acetosuccinic ester, with the alcohol and carbonic acid de- compositions, into isonitrosolsevulinic acid (compare isonitroso acetone, p. 326) : C0 2 C 2 H 5 NO. OH CO, . C,H 6 . CH, . iH . CO . CH,-!^-^ '" ' CH ' C = N < H > ' C ' CH " 0X0- OR KETOGLUTARIC ACID GROUP. a-Oxoglutaric Acid is not known, and the body formerly considered* as such is oxymeihylene succinic ester (p. 495). Cyan-oximidobutyric Acid, CO 2 H.CH 2 .- CHj. C = (NOH)CN, melting at 87, is a derivative of a-oxoglutaric acid. It is formed when cold sodium hydroxide acts upon furazan propionic acid (p. 483). When it is boiled with sodium hydroxide a-OximiJoglutaric Acid, CO 2 H . CH 2 . - CH 2 C = N(OH)CO 2 H, melting at 152, is the product (A. 260, 106). Acetone Dicarboxylic Acid, /5-keto- or /?-oxoglutaric acid, CO(CH 2 CO 2 H) 2 , melts at about 130, and decomposes into CCX, and acetone. It may be obtained by warming citric acid with concen- trated sulphuric acid (v. Pechmann, B. 17, 2542 ; 18, R. 468; A. 278, 63). Acetone dicarboxylic acid dissolves readily in water and ether. The 502 ORGANIC CHEMISTRY. same alteration which takes place on heating the acid alone occurs on boiling it with water, acids, or alkalies. The solutions of the acid are colored violet by ferric chloride. Hydrogen reduces the acid to /2-oxyglutaric acid (p. 494). PC1 5 converts the acid into /3-chlorglutaconic acid. Hydroxylamine changes it to oximidoacetone dicarboxylic acid, CO 2 H . CH 2 . - C(NOH)CH 2 CO 2 H -f H 2 O, melting at 53-54. In the anhydrous state it melts at 89 (B. 23, 3762). Nitrous acid converts acetone dicarboxylic acid into diisonitroso- acetone (p. 479) and CO, (B. 19, 2466 : 21, 2998). The acid is condensed by acetic CH 3 .CO.CH.CO.C.C0 2 H anhydride to dehydracetcarboxylic acid, I (A. 273,186). CO O CCH 3 The salts break down into acetone and carbonates. Esters : Dimethyl Ester boils at 128 (1 2 mm.). The diethyl ester boils at 138 (12 mm.) (B. 23, 3762; 24, 4095). The four H -atoms of the two CH 2 groups in it can be successively replaced by alkyls (B. 18, 2289), arj d they also readily condense with aldehydes (B. 29, 994; R. 93). Ammonia and the diethyl ester combine to form /3-oxyamidoglutaminic ester, which condenses further to glutazine (see this) a trioxypyridine derivative (B. 19, 2694). Alcoholic ammonia produces 8-amidoglufa- conic ester (B. 23, 3762). Nitrous acid converts the ethyl ester into the oximido- compound, CO 2 C 2 H 5 C: N(OH)CO .CH 2 . CO 2 C 2 H 5 , which then passes into oxyisoxa- zole-dicarboxylic ester, CO 2 . C 2 H 5 . C = (NQ)C(OH) : C. CQ 2 C 2 H 5 (B. 24, 857). Fuming nitric acid changes it to the peroxide, CO 2 . C 2 H 5 . C : N(O)CH 2 . C : N(O) . - CO 2 C 2 H 5 (B. 26, 997). The phenylhydrazones of the acid and of the ester readily change to a corresponding lactazam a pyrazolon derivative, (B. 24, 3253)- Acetyl-n-glutaric Acids are produced by the action of /5-iodo- propionic ester upon the sodium derivatives of acetoacetic ester and alkvlic acetoacetic esters : C0 2 C 2 H 5 a-Acetglutanc Ester, C H S . C OCH . CH 2 . CH 2 . CO 2 . C 2 H 5 ' boils at 2 7" 272. C0 2 . C 2 H 5 a-Ethyl-a-Acetglutaric Ester, . CH 2 . CO 2 C 2 H 5 ' d composes when it is distilled. By the elimination of carbon dioxide the free acids change into the corresponding d-ketonic acids (p. 383) (A. 268, 113). /?-Acet-glutaric Acid, CH 3 . CO . CH[CH 2 . CO 2 H] 2 , melting at CH 2 . COO 47-50, is obtained from its keto-dilactone, CH.C.CH,, melting at CH 2 .COO 102 and boiling at 205 (12 mm.), by prolonged boiling with water. The ketodilactone is produced on decomposing /J-acettricarballylic ester with boiling hydrochloric acid (A. 295, 94). THE URIC ACID GROUP. 503 Acetone-diacetic Acid, Hydrochelidonic Acid, CO<^ 2 ' CH* ' C^H ' lcevulin - acetic acid, HOCHHOOH' 1OSCS ^^ "^ beC meS tbe >" dilactone ' C 7 H 8 4 : ' CH 2 .CH 2 .C.CH 2 .CH 2 I /\ I CO - O O - CO This is formed when succinic acid is boiled for some time : 2 C 4 H 6 O 4 = C 7 H 8 4 -f C0 2 + 2H 2 0. It melts at 75, and distils without decomposition under reduced pressure. Boil- ing water, or, better, boiling alkalies cause it to become acetone diacetic acid, by absorption of water. This acid is identical with propion-dicarboxylic acid, and hydro- ihelidonic acid. The first is obtained by the action of HC1 upon furfur-acrylic acid, and the latter by the reduction of chelidonic acid. Acetone-diacetic acid melts at 143. Acetyl chloride or acetic anhydride will again convert it into the y-dilactone. Hydroxylamine changes it to the oxime, C(N. OH)(C 2 H i . CO 2 H) 2 , melting at 129 with decomposition. Its phenylhydra- zone, C(N 2 H . C 6 H 5 )(C 2 H 4 . CO 2 H) 2 , melts at 107 (A. 267, 48). Phoronic Acid, CO<^ 2 ' ScH*] 8 ' CO'H ( ? )' meltin at l8 4' is obtained from the dihydrochloride addition product of phorone (p. 221), by its successive treatment with potassium cyanide and hydrochloric acid (B. 26, 1173). The corre- sponding y-dilactone melts at 134 (A. 247, no). THE URIC ACID GROUP. Uric acid is a compound of two cyclic urea residues combined with HN CO a nucleus of three carbon atoms: OC C NH By its oxida- I II >CO. HN C NH tion the so-called urei'des of two dicarboxylic acids oxalic acid and mesoxalic acid were made known. The urei'de of a dicarboxylic acid is a compound of an acid radical with the residue, NH . CO . NH ; e. g., CO NH. ( i, f) >CO =ureide of oxalic acid, oxalyl urea, parabanic acid. They are closely related to the imides of dibasic acids, succinimide (p. 448), and phthalimide, and parabanic acid may, for example, be regarded as a mixed cyclic imide of oxalic and carbonic acids. Like the imides, they possess the nature of an acid, and form salts by the replacement of the imide hydrogen with metals. The imides of dibasic acids are converted by alkalies and alkaline earths into amino-acid salts, which split off ammonia and become salts of dibasic acids. Under similar conditions the urei'de ring is ruptured. At first a so- 504 ORGANIC CHEMISTRY. called wr-acid is produced, which finally breaks down into urea and a dibasic acid : CH 2 . COOH CH 2 .COOH +NH ' Succinic Acid. COOH NH 2 CH 2 CO CH 2 . CONH 2 CH 2 .CO > Succinimide CO NH 1 ^ PO CH 2 . COOH Succinamic Acid CO . NH . CO V^. 1 I CO-NH > Parabanic Acid C0 2 H NH 2 Oxaluric Acid Oxalic Urea. Acid The names of a series of ureides having an acid character end in "uric acids," e.g., barbituric acid, violuric acid, dilituric acid. These names were constructed before the definition of the ur-acids given above, and it would be better to abandon them and use the ureide names exclusively, e.g., malonyl urea, oximidomesoxalyl urea, nitromalonyl urea, etc. It is the purpose to discuss the urea derivatives of aldehyde- and keton-carboxylic acids, of glyoxalic acid and acetoacetic acid in connection with the ureides and " ur " acids of the dicarboxylic acids. These are allantoin and methyl uracil. The first can also be prepared from uric acid, while the methyl uracil constitutes the start- ing out material for the synthesis of uric acid. Xanthine, theobromine, theophylline, theine or caffeine, and guanine, hypoxanthine, adenine, etc., are related to uric acid. Ureides or Carbamides of Aldehyd- and Keto-mono-car- boxylic Acids. These bodies ally themselves with the ureides of the oxyacids, hydantoi'n, and hydantoic acid, which have already been discussed (p. 401). Glyoxyl Urea and Allanturic Acid, CO< i ' (?), and H . CO . NH 2 NH CH NH (50-NH >C ( ? )' aswellasAllanto ' in ' CO < NH C l O-N of glyoxylic acid. Allantoin is present in the urine of sucking calves, in the allantoic liquid of cows, and in human urine after the ingestion of tannic acid. It has also been detected in beet-juice (B. 29, 2652). It is produced artificially on heating glyoxalic acid (also mesoxalic acid, CO(CO 2 H) 2 ) with urea to 100. Allan to'in is formed by oxidizing uric acid with PbO 2 ,MnO 2 , potassium ferri- cyanide, or with alkaline KMnO 4 (B. 7, 227). Allanto'in crystallizes in glistening prisms, which are slightly soluble in cold water, but readily in hot water and in alcohol. It has a neutral reaction, but dis- solves in alkalies, forming salts. Sodium amalgam converts allantoin into glyco-uril, or acetylene urea. Allanturic acid is obtained from allantoin on warming with baryta water or with PbO 2 , and by the oxidation of glycolyl urea (hydantoin, p. 401). CARBAMIDES OF DICARBOXYLIC ACIDS. 505 Glyoxyl urea, stout needles dissolving readily in water, is a decomposition product of oxonic acid, C 4 H 6 N 3 O 4 , resulting from the oxidation of uric acid (A. 175, 234). Pyruvil, CO<^ i ( >CO(?), is formed when pyroracemic acid and NH 2 CO - NH urea are heated (A. chim. phys. [5] n, 373) together. Methyl Uracyl, CH. co, i s produced when urea acts upon acetoacetic ester. It is the starting-out material for the syn- thesis of uric acid. To convert it into the latter it is first changed into derivatives of the hypothetical uracyl, CH/ ~ NHX O> pare synthesis of uric acid, p. 513 (A. 251, 235). UREIDES OR CARBAMIDES OF DICARBOXYLIC ACIDS. The most important members of this class are parabanic acid and alloxan. They were first obtained by oxidizing uric acid with nitric acid. These cyclic ure'ides by moderated action of alkalies or alkaline earths are hydrqlyzed and become " ur "-acids. When the action of the alkalies is energetic, the products are urea and dicarboxylic acids e. g. : CO_NH H 2 C0 2 H NH 2 H 2 O CO 2 H NH 2 CO_NH > BatOH)^ CO NH > (KOH)~^ CO 2 H + NH 2 > Oxalyl Urea Oxaluric Oxalic Carbamide Parabanic Acid Acid Acid Urea. Oxalyl Urea, co< I , Parabanic Acid, is produced in the oxidation of uric acid and alloxan with ordinary nitric acid (A. 182, 74). It is synthetically prepared by the action of POC1 3 upon a mix- ture of urea and oxalic acid. It is soluble in water and alcohol, but not in ether. Its salt are unstable ; water converts them at once into oxalurates. Silver nitrate precipitates the crystalline disilver salt, C 3 Ag 2 N 2 O 8 , from solutions of the acid. Oxalylmethyl Urea, Methyl Parabanic Acid, C 3 H(CH 3 )N 2 O 3 , is formed by boiling methyl uric acid, or methyl alloxan, with nitric acid, or by treating tbeo- bromine with a chromic acid mixture. It is soluble in ether, and melts at 149.5. Oxalyldimethyl Urea, Dimethyl Parabanic Acid, C 3 (CH 3 ) 2 N 2 O 3 , Choles- trophane, is obtained from dimethyl alloxan and theine by oxidation, or by heating methyl iodide with silver parabanate. It melts at 145 and distils at 276. Oxaluric Acid, CO<^ : ' H , results from the action of bromine upon parabanic acid. Free oxaluric acid is a crystalline powder, dissolving with difficulty. When boiled with alkalies or water, it decomposes into urea and oxalic acid; heated to 200 with POC1 3 , it is again changed into parabanic acid. 43 506 ORGANIC CHEMISTRY. The ammonium salt, C 3 H 3 (NH 4 )N 2 O 4 , and the silver salt, C 3 H 3 AgN. 2 O 4 , crystal- lize in glistening needles. The ethyl ester, C 3 H 3 (C 2 H 5 )N 2 O 4 , is formed by the action of ethyl iodide on the silver salt, and has been synthetically prepared by letting ethyl oxalyl chloride act upon urea. It melts at 177. Oxaluramide, CO< ' C ' CO> NHa ' Oxalan, is produced on heating ethyl oxalurate with ammonia, and by fusing urea with ethyl oxamate. NHCO Oxalyl Guanidine, HN : C< I , is formed from oxalic ester and guanidine (B. 26, 2552; 27, R. 64). Malonyl Urea, CO<^ ' ^>CH 2 , Barbituric Acid, is obtained from allox- antin by heating it with concentrated sulphuric acid, and from dibrombarbituric acid by the action of sodium amalgam. It may also be synthetically obtained by heating malonic acid and urea to 100 with POC1 3 . It crystallizes with two mole- cules of water in large prisms from a hot solution, and when boiled with alkalies is decomposed into malonic acid and urea. The hydrogen of CH 2 in malonyl urea can be readily replaced by bromine, N0 2 , and the isonitroso-group. The metals in its salts are joined to carbon, and may be replaced by alkyls (B. 14, 1643; 15, 2846). When silver nitrate is added to an ammoniacal solution of barbituric acid, a white silver salt, C i H 2 Ag 2 N 2 O 3 , is precipitated. Methyl iodide converts this into a-Dimethylbarbituric Acid, CO<^ ' ^Q>C(CH 3 ) 2 . This forms shining laminae, does not melt at 200, and sublimes readily. Boiling alkalies decompose it into CO 2 , NH 3 , and dimethyl malonic acid. Its isomeride, /5-Dimethyl Bar- bituric Acid, CO CH 2' is P roduced from mal o nic acid and dimethyl urea through the agency of POC1 3 , or by the reduction of dichlormalonyl dimethyl urea (B. 27, 3084). It melts at 123. Malonyl Guanidine, NH : C< NH ' CQ >CH 2 , f r0 m malonic ester and guanidine (B. 26, 2553), affords derivatives analogous to those of malonyl urea, e. g., isonitrosomalony I guanidine, NH : C< NH ' Q>C : N . OH, which hydrogen sulphide reduces to amido- malonyl guanidine, NH: C< NH ' CO >CH . NH 2 . Potassium cyanate converts the latter into imidopseudo-uric acid, carbamidomalonyl guanidine, NH : C< ; >CH - NH . CO . NH 2 . Tartronyl Urea, CO CH ' OH ' Dialuric Add , is formed by the reduction of mesoxalyl urea (alloxan) with zinc and hydrochloric acid, and from dibrombarbituric acid by the action of hydrogen sulphide. On adding hydrocyanic acid and potassium carbonate to an aqueous solution of alloxan, potassium dialurate separates but potassium oxaluiate remains dissolved : 2C 4 H 2 N 2 O 4 -f 2KOH = C 4 H 3 KN 2 4 + C 3 H 3 KN 2 O 4 + CO 2 Potassium Dialurate Potassium Oxalurate. Dialuric acid crystallizes in needles or prisms, shows a very acid reaction, and forms salts with I and 2 equivalents of the metals. It becomes red in color in the air, METHYL URAMILS. 507 absorbs oxygen and passes over into alloxantin, 2C 4 H 4 N 2 O 4 -f O = C 8 H 4 N 4 O 7 -f Tartronyl Dimethyl Urea, CO< 3 ' >CH . OH, melts at about 170 with decomposition (B. 27, 3082). Nitromalonyl Urea, Nitrobarbituric Acid, Dilituric Acid : NHCC is obtained by the action of fuming nitric acid upon barbituric acid and by the oxidation of violuric acid (B. 16, 1135). It crystallizes with three molecules of water and can exchange three hydrogen atoms for metals. Nitromalonyl Dimethyl Urea melts at 148 (B. 28, R. 321). Amidomalonyl Urea, Amide-barbituric Acid, CO<^ ' ^Q>CHNH 2 (Uramil. Dialuramide, Murexan), is obtained in the reduction of nitro- and isonitroso- barbituric acid with hydriodic acid ; by boiling thionuric acid with water, and by boiling alloxantin with an ammonium chloride solution. Alloxan remains in solution, while uramil crystallizes out. It is only slightly soluble in water, and crystallizes in colorless, shining needles, which redden on exposure. Murexide (p. 510) is pro- duced when the solution is boiled with ammonia. Nitrous acid converts uramil into alloxan. Methyl Uramils. In order to indicate the positions of the methyl groups, the uramil carbon and nitrogen atoms are marked with the numbers I to 7, according to the following diagram, which shows the numbering of the uric acid nucleus (p. 511) : l.l-Dimtthyl Uramil, CHCH ' NH 2' melts with decom P osi - tion at 200. It is produced when hydrochloric acid acts upon ammonium dimethyl hionurate, CO[N(CH 8 )CO], . CH . NH . SO 3 NH 4 -f- 2H 2 O the product resulting from the action of ammonia, sulphur dioxide, and ammonium carbonate upon a solu- tion of dimethyl alloxan (B. 27, 3088). i.^T-Trimefhyl Uramil, COCH. NH . CH 3 , decomposes when rapidly heated at 200. It is formed from dimethyl alloxan by the action of methyl- amine sulphite, and then hydrochloric acid (B. 30, 564). Amidomalonyl Guanidine, see Methyl Guanidine, p. 506. Pseudouric Acid, Carbamidomalonyl 6r^,CO<^ ' o> CHNH CONH 2 - Uramil and urea heated to 180 yield the ammonium salt of this acid. The potassium salt is obtained from uramil or from murexide and potassium cyanate. Methyl Pseudouric Acids are obtained from the corresponding methyl uramils, which for this purpose need not be isolated, when they are treated with potassium cyanate. When heated to 150 with fusing oxalic acid, or when boiled with hydro- chloric acid, they lose water, and yield the corresponding uric acids. In this manner the following bodies have been prepared : 7 Monoiruthyl Pseudn-uric Acid, i.^-Dimcthylpseudo-uric Acid, l.T ) . f j-Trimethyf Pseudo-uric Acid (B. 30, 559), 2-Imidopseudo-uric Acid, Carbamidomalonyl Guani- dine, p. 506. Thiouramil, CONH 2 , /3-Thiopseudouric Acid CO< NH ' C(SH) / C - NHCaNH 2> is obtained from thiouramil and potassium cyanate (A. 288, 171). Alloxan, Mesoxalyl Urea, CO C C Violuric Acid Uramil. (l) Reducing agents, e. g. y hydriodic acid (SnCl 2 , H 2 S, Zn and hydrochloric acid), convert alloxan in the cold into alloxantin (p. 509); (2) on warming, into dialuric acid (p. 506). (3) Alloxantin digested with concentrated sulphuric acid becomes barbituric acid (p. 506) ; (4) fuming nitric acid changes it to dilituric acid ; (5) and with potassium nitrite it yields violuric acid. (6) (7) Uramil results from the reduction of dilituric acid and violuric acid. (8) Dilituric acid is formed when violuric acid is oxidized. (9) Hydroxylamine converts alloxan into its oxime violuric acid. (10) Boiling dilute nitric acid oxidizes alloxan to parabanic acid and C0 2 . The primary alkali sulphites unite with alloxan just as they do with mesoxalic acid, and we can obtain crystalline compounds, e. g., C 4 H 2 N 2 O 4 . SO 3 KH -f- H 2 O. Pure alloxan can be preserved without undergoing decomposition, but in the presence of even minute quantities of nitric acid it is converted into alloxantin. Alkalies, lime or baryta water change it to alloxanic acid, even when acting in the cold. Its aqueous solution undergoes a gradual decomposition (more rapid on heating) into alloxantin, parabanic acid, and CO 2 . For the action of o-diamines upon alloxan, see B. 26, 540; for that of pyrazolon derivatives, see A. 255, 230. Methyl Alloxan, CO<^^ H ^ ~ ^>CO, is produced by the oxidation of methyl uric acid. DIURElDES. 509 Dimethyl Alloxan, CO<^^(pi , a Q>CO, is produced when aqueous chlorine (hydrochloric acid and KC1O 3 ) acts on the'ine, and by the careful oxidation of tetramethyl alloxantin (B. 27, 3082). When it is boiled with nitric acid, methyl and dimethylparabanic acids are formed. Dibrommalonyl Urea, Dibrombarbituric Add, CO<^^>CBr 2 , results when bromine acts upon barbituric acid, nitro-, amido- and isonitroso-barbituric acids. Oximidomesoxalyl Urea, Isonitrosobarbituric Acid, Viol-uric Acid, the oxime of alloxan, the first known "ketoxime," is obtained by the action of potassium nitrite on barbituric acid, and of hydroxylamine upon alloxan. It unites with metals to form blue, violet, or yellow colored salts. When heated with the alkalies, it breaks down into urea and isonitrosomalonic acid (p. 498). Oximido- mewxalyl Dimethyl Urea melts at 141 (B. 28, 3142 ; R. 912). Alloxan phenyihydrazone melts with decomposition at 295-300 (B. 24, 4140). Alloxan semicarbazidc decomposes at 260 (B. 30, 131). Thionuric Acid, CO< ' Q>C<| i , sulphamidobarbituric acid, is ob- tained by heating isonitrosobarbituric acid or alloxan with ammonium sulphite. Di- methyl Thionuric Acid, see B. 27, 3086. Alloxanic Acid, CO<55 CO CO CO OH . If baryta water be added to a Att 2 . warm solution of alloxan, as long as the precipitate which forms continues to dissolve, barium alloxanate, C 4 H 2 BaN 2 O 5 -f- 4H 2 O, will separate out in needles when the solution cools. To obtain the free acid, decompose the barium salt with sulphuric acid and evaporate at a temperature of 30-40. A mass of crystals is obtained by this means. Water dissolves them easily. Alloxanic acid is a dibasic acid, inasmuch as both the hydrogen of carboxyl and of the imide group can be exchanged for metals. When the salts are boiled with water, they decompose into urea and mesoxalates (P- 497)- Diure'ides. Parabanic acid, alloxan, and dimethyl alloxan are ureides. Two molecules of each unite, and by reduction the diure'ides result. They are oxalantin, alloxantin, and amalic acid. These probably sustain the same relation to the simple ureides that tetra- methyl ethylene oxide (p. 299), the anhydride of pinacone, bears to acetone. Oxalantin, C 6 H 6 N 4 O 6 , Leucoturic Acid, is obtained by the reduction of para- banic acid. Alloxantin, CO<^ ' ^O>C -C CO + 3H 2 O (?;, is obtained by reducing alloxan with SnCl 2 , zinc and hydrochloric acid, or H 2 S in the cold; or by mixing solutions of alloxan and dialuric acid. It can also be obtained from convicin, a substance from Vicia Fnba minor and Viet a sativa, when they are heated with sulphuric or hydrochloric acid (B. 29, 2106). It is most readily prepared by wanning uric acid with dilute nitric acid (A. 147, 367). It crystallizes from hot H 2 O in small, hard prisms with 3H. 2 O and turns red in air containing ammonia. Its solution has an acid reaction ; ferric chloride and ammonia give it a deep blue color, and baryta water produces a violet precipitate, which on boiling is converted into a mixture of barium alloxanate and dialurate. On boiling alloxantin with dilute sulphuric acid, it changes to the ammonium salt of hydurilic acid, C 8 H e N 4 O 6 -|- 2H 2 O. It combines with cyanamide, forming isouric acid (B. 29, 2107). 5IO ORGANIC CHEMISTRY. Tetramelhyl Alloxantin, C 8 (CH 3 ) 4 N 4 O 7 , Amalic Acid, is formed by the action of nitric acid or chlorine water upon thei'iie, or, better, by the reduction of dimethyl alloxan (see above) with hydrogen sulphide (A. 215, 258). Its deportment is similar to that of alloxan. Purpuric Acid, C 8 H 5 N 5 O 6 , is not known in the free state, because as soon as it is liberated from its salts by mineral acids it immediately decomposes into alloxan and uramil. The ammonium salt, C 8 H 4 (NH 4 )N 5 O 6 -\- H 2 O, is the dye-stuff mur- exide. This is formed by heating alloxantin to 100 in ammonia gas ; by mixing ammoniacal solutions of alloxan and uramil ; and by evaporating uric acid with dilute nitric acid and pouring ammonia over the residue (murexide reaction). Murexide separates from the solution on cooling. It forms four-sided plates or prisms with one molecule of H 2 O, and has a gold-green color. It dissolves in water with a purple-red color, but is insoluble in alcohol and ether. It dissolves with a dark blue color in potash ; on boiling, NH 8 is disengaged and the solution decolorized. NH.C.Ntr" Uric Acid, C 5 H 4 N 4 O 3 ,CO G-NH j is a white, crystalline, I NH-CO sandy powder, discovered by Scheele in 1776 in urinary calculi. It occurs in the juice of the muscles, in the blood and in the urine, especially of the carnivorae, the herbivorse separating hippuric acid ; also, in the excrements of birds, reptiles and insects. When urine is exposed for a while to the air, uric acid separates ; this also occurs in the organism (formation of gravel and joint concretions) in certain abnormal conditions. History. Liebig and Wohler (1826) showed that numerous transposition products could be obtained from uric acid. Their relationships and constitution were chiefly explained by Baeyer in 1863 and 1864. In consequence of certain experiments of A. Strecker, Medicus (1875) proposed the structural formula given above for the acid. This was conclusively proven by E. Fischer in his investigation of the methy- lated uric acids. The results derived from analysis were confirmed by the synthesis made in 1888 by R. Behrend and O. Roosen. They proceeded from acetoacetic ester and urea (p. 513). Horbaczewski (1882-1887) had previously made syntheses of uric acid at elevated temperatures, but obtained poor yields. They consisted in melting together glycocoll, trichlorlactamide, etc., with urea. No clue as to the constitution of the acid could be deduced from these. In 1895 E. Fischer and Lorenz Ach showed how pseudouric acid, previously synthesized by A. Baeyer, could by fusion with oxalic acid be converted into uric acid. Preparation. Uric acid is best prepared from guano or the excrements of reptiles. Properties. Uric acid is a shining, white powder. It is odorless and tasteless, insoluble in alcohol and ether, and dissolves with difficulty in water; i part requires 15,000 parts water of 20 for its solution, and 1800 parts at 100. Its solubility is increased by the presence of salts like sodium phosphate and borate. Water precipi- tates it from its solution in concentrated sulphuric acid. On evap- URIC ACID. 511 orating uric acid to dryness with nitric acid, we obtain a yellow residue, which assumes a purple-red color if moistened with ammonia, or violet with caustic potash or soda (murexide reaction, p. 510). Uric acid heated with ammonium sulphide changes to thiouramil (P- 5?)- Heat decomposes uric acid into NH 3 , CO 2 , urea, and cyan- uric acid. Uric acid is a weak dibasic acid. It forms primary salts with the alkaline carbonates. The secondary alkali salts are obtained by dissolving the acid in the hydroxides of potassium and sodium; they are changed to the primary form by CO 2 and water. When CO 2 is conducted through the alkaline solution, the primary salts are pre- cipitated. The primary salt, C 5 H 3 KN 4 O 3 , dissolves in 800 parts of water at 2Q. The primary sodium salt is more insoluble. Ite primary ammonium salt is a sparingly soluble powder. The lithium salt (Lipowitz) is much more soluble (in 368 parts of water at 19) (A. 122, 241), hence lithium mineral waters are used in such diseases where there is an excessive secretion of uric acid. This salt is, however, greatly sur- ~ " passed by \hepiperazine salt, C 5 H 4 N 4 O 3 . NH< 2 ' |j >NH (Finzelberg), which dissolves in 56 parts of water at 17 (B. 23, 3718). The lysidine or the methyl- glyoxalidine salt (Ladenburg) is even more soluble (one part in 6 parts of water ; B. 27, 2952). Methyl Uric Acids. The four hydrogen atoms in uric acid can be replaced by methyl. In all methyl uric acids the methyl groups are linked to nitrogen ; this is also the case with tetramethyl uric acid, and in conjunction with the decompositions and NH CO CO C NH synthesis of uric acid, argues for the formula, i II ^>CO, without, how- NH C NH ever, in the light of our present representations, in any way attaching to formulas such as follow, or any like them : N = C.OH HO.C C NH V II II JxC.OH. N C N ^ To indicate the position of the methyl groups in the methyl uric acids and the con- stitution of other bodies containing the same hetero-twin ring, E. Fischer suggested that the carbon and nitrogen atoms of the nucleus contained in uric acid and bodies related to it be numbered, and that the hydrogen compound of the nucleus, C 5 N i H 4 , which could have two formulas, should be called "purin": N -- C N = CH N = CH C2 5 C N 8 HC C NH HC C N Purin. Methyl uric acids are obtained by treating urate and methyl urate of lead (also the potassium salts) with methyl iodide. The corresponding pseudouric acids (p. 507) 512 ORGANIC CHEMISTRY. split off water and yield them. Three mono-, four di-, and two tri-methyl uric acids are known in addition to tetramethyl uric acid. g-Afethyl Uric Acid ((3) is formed together with I- or -^-Methyl Uric Acid (a) when lead urate is treated with methyl iodide in ether at 150-160. The first is converted by nitric acid into alloxan, the second into methyl alloxan. When heated with hydro- chloric acid both pass into glycocoll. ^-Methyl Uric Acid (y-) is obtained from 7-methyl pseudouric acid (p. 507). i-9-or "$.<)- Dim ethyl Uric Acid (a-) is made from basic lead urate and methyl iodide. 7,*)- Dimethyl Uric Acid (ft-) see B. 17, 1780. 1.3- Dimethyl Uric Acid (y-) is obtained from 1.3-dimethyl pseudouric acid (p. 507); see also theophyllin (p. 515). $.7 -Dimethyl Uric Acid (6) is formed from 7-methyl uric acid; see also theobromine (p. 514). 3-7-9- Trimethyl Uric Acid (a-) is derived from 7-9-dimethyl uric acid. 1-3-7- 7 ^'im ethyl Uric Acid, from i.3.7-trimethyl pseudouric acid (a-), is identical with hydroxycaffein (B. 30, 567). Tetramethyl Uric Acid is made from trirnethyl urate of potassium and methyl iodide. OXIDATION OF URIC ACID. Mesoxalyl urea or alloxan and oxalyl urea or parabanic acid are produced when uric acid is oxidized with ordinary nitric acid. When the acid is carefully oxidized either with cold nitric acid or with potassium chlorate and hydrochloric acid, it yields mesoxalyl urea and urea. Allanto'in is produced when potassium permanganate, or iodine in caustic potash, acts upon the a'cid (B. 27, R. 902). When air or potassium permanganate acts upon the alkaline solution of uric acid (B. 27, R. 887; 28, R. 474), uroxanic acid, C 5 H 8 N 4 O 6 , is produced; this the alkali changes to oxonic acid, C 4 H 5 N 3 O 4 . These are two bodies whose constitution has not yet been made clear. These reac- tions suggest the following diagram, in which the breaking-down of alloxan and parabanic acid is considered : NH CO NH CO NH C NH NH-CO Parabanic Acid >co in-cio -'- NH CO Alloxan | Uric Acid I C 5 H 8 N 4 O 6 * NH CO * NH CO Uroxanic Acid I I CO CO CO C 4 H 5 N 8 O 4 I NH 2 CO 2 H i NH 2 Oxonic Acid Alloxanic Acid Oxaluric'Acid NH.CH.NH *NH 2 CO 2 H ^N] I I >CO II I CO CO.NH CO CO CO NH 2 NH 2 CO 2 H NH 2 CO 2 H Allantom Mesoxalic Acid Oxaluric Acid. One of the two isomeric monomethyl uric acids, when oxidized, yields monomethyl alloxan and urea, the other alloxan and mono- methyl urea. These reactions are readily understood if we assume the constitutional formula of uric acid to be as indicated above (E. Fischer, B. 17, 1785). SYNTHESIS OF URIC ACID. 513 Uric acid is the diureide of the hypothetical body, CO = C(OH) . CO 2 H, or C(OH) a = C(OH) CO 2 H the pseudo-form of the half- aldehyde of mesoxalic acid, CHO . CO . CO 2 H, which has not yet been prepared. SYNTHESIS OF URIC ACID: (i) FROM ACETOACETIC ESTER; (2) FROM MALONIC ACID. (i) From Acetoacetic Ester : f i) Acetoacetic ester and urea unite to $-uramido- crotonic ester. When this is saponified with alkali it yields an acid which, in a free state, splits off water and becomes a cyclic ureide methyl uracyl. (2) Nitric acid converts the latter into nitrouracyl carboxylic acid, (3) whose potassium salt when boiled with water loses a molecule of carbonic acid, and becomes the potassium salt of nitrouracyl. (4) The reduction of the latter with tin and hydrochloric acid gives in part amidouracyl, and in part oxyuracyl or isobarbituric acid. (5) Bromine water oxidizes the latter to isodiahtric acid, which when heated (6) with urea and sulphuric acid yields uric acid (A. 251, 235). CO,C 2 H 5 k CO . CH 3 Acetoacetic Ester (i) NH.CO NH C CO CO CH > CO C N0 2 NH.C.CH 3 Methyl Uracyl NH., C-CO,H Nitrouracylic Acid NH CO CO C N0 3 1 II NH-CH Nitrouracyl NH CO CO CNH 2 NH CH Amidouracyl NH CO NH CO CO C(OH) - } ->CO C NH Oxyuracyl (Isobarbituric Acid) NH C.OH Isodialuric Acid NH >CO. C NH Uric Acid. (2) From Malonic Acid: (i) Urea and malonic acid heated to 100 with POC1 3 yield malonyl urea, which (2) nitrous acid converts into oximido-mesoxalyl urea or violuric acid. (3) When the latter is reduced, amidomalonyl urea or uramil results. (4) This is changed by potassium cyanate into pseudouric acid. (5) On withdrawing water from pseudouric acid by means of molten oxalic acid or boiling hydrochloric acid, uric acid results (B. 30, 559) : CO 2 H (i) f~*VT NH.CO co en NH.CO (2) > CO C-N OH CH, C0 2 H Malonic Acid "r v^u v--H 2 NH.CO Malonyl Urea NH.CO Oximidomesoxalyl Urea. (3) NH .CO NH . CO NH . CO CO CHNH 2 ^ co CHNH . CONH 2 ^-> CO C . NH I II II > CO ' NH . CO NH . CO NH . C . NH Since alloxan and dimethyl alloxan yield methylated pseudouric acids, methylated uric acids can also be synthesized in this way. Xanthine Group. Guanine, xanthine, hypoxanthine, and carnine stand in close relation to uric acid. Like it, they occur as products of the metabolism of the animal 514 ORGANIC CHEMISTRY. organism. Xanthine and hypoxanthine occur in the extract of tea. Theobromine, theophylline, and theine or caffeine methyl derivatives of xanthine are found in the vegetable kingdom : HN CO HN CO I I / CH * CO CH 3 . N C ] Theobromine r*H N CO \-xXAo . IN ' V_/Vy s-1-r j . s. C C N\ CH 3 .N C N ^ CH S .N C N^ Theophylline Caffeine, or Theine. The breaking-down of xanthine into alloxan and urea, and of caffeine into dimethyl alloxan and methyl urea, by means of potassium chlorate and hydrochloric acid, are particularly important in the explanation of their constitution. Nitrous acid converts guanine into xanthine, and by decomposition yields guani- dine, (NH 2 ) 2 C:NH (p. 411), hence it must be regarded as xanthine in which a guanidine residue takes the place of a urea-residue ; i. e. , the oxygen of a CO group is replaced by imide NH. Adenine bears the same relation to hypoxanthine that guanine sus- tains to xanthine, inasmuch as it is converted by nitric acid into hypo- xanthine. The xanthine group compounds occur in beet juice (B. 29, 2649) : HN CO HN CO N = C.NH 2 HN = C C NH V HC C NH X ^ HC C NHv I II ^>CH II II ^>CH II II ^CH Guanine Hypoxanthine Adenine. Xanthine (see constitutional formula above) occurs in slight amounts in many animal secretions, in the blood, in urine, in the liver, in some forms of calculi, and in tea extract. It results from the action of nitrous acid upon guanine (A. 215, 309). It is a white, amorphous mass, somewhat soluble in boiling water, and com- bines with both acids and bases. It is readily soluble in boiling ammonia ; silver nitrate precipitates C 5 H 2 Ag 2 N 4 O 2 4- H 2 O from its solution, The corresponding lead compound yields theobromine (dimethyl xanthine) when heated to 100 with methyl iodide. When xanthine (analogous to caffeine, page 515) is warmed with potassium chlorate and hydrochloric acid it splits into alloxan and urea. Heteroxanthine, ^-methyl xanthine, occurs in small quantities in urine (B. 18, 3406), and is formed from theobromine by the splitting off of methyl (B. 28, Iil8; 29, R- 475 30, 554). Theobromine, $.*] -dimethyl xanthine, occurs in cocoa-beans (from Theobroma Cacao} and is prepared by introducing methyl into xanthine (see above). Theobromine is a crystalline powder with a bitter taste and dissolves with difficulty in hot water and alcohol, but rather easily in ammonium hydroxide. It sublimes (about 290) without decomposition, when it is carefully heated. It has a neutral reaction, but yields crystalline salts on dissolving in acids ; much water will decom- pose these. Silver nitrate precipitates the compound, C 7 H 7 AgN 4 O 2 , in crystalline form from the ammoniacal solution after protracted heating. When this salt is heated with methyl iodide it yields methyl theobromine, C 7 H^(CH,,)N 4 O 2 , i. e., caffeine. Paraxanthine, 1.7 dimethyl xanthine, occurs in urine (13. 18, 3406). It can also be prepared from theobromine, from which a methyl group can easily be split off and again introduced in another position. It passes by methylation into caffeine (B. 30, 554). THEOPHYLLINE. CAFFEINE. 515 Theophylline, 1.3 dimethyl xanthinc, melting at 264, was dis- covered in 1888 by Kossel in tea extract. By the action of methyl iodide upon silver theophylline he obtained caffeine (B. 21, 2164). Theophylline has been synthetically prepared from 1.3- or ^-dimethyl uric acid by its conversion with PC1 5 into chlortheophylline. This melts at about 300 with decomposition ; hydriodic acid reduces it to theophylline (E. Fischer, B. 30, 553) : CO c_ CH 3 . N CO NH >CO oo C NH- CH 3 .N CO CO C NH> y-Dimethyl Uric Acid CH 3 . N C N^ 'Chlortheophylline CH 3 . N C N Theophylline. Caffeine, Coffei'ne, Thei'ne, i.^-trimethyl xanthine, occurs in the leaves and beans of the coffee tree (}4 P er cent.), in tea (2-4 per cent.), in Paraguay tea (from Ilex paraguayensis} , in guarana (about 5 P er cent.), the roasted pulp of the fruit of Panllinia sorbilis, and in the cola nuts (3 per cent.). It is also found in minute quantities in cocoa. It is used in medicine as a nerve stimulant. Caffeine consists of long, silky needles with one molecule of water ; they are only slightly soluble in cold water and alcohol. At 100 it loses its water, and melts at 233. It has a feeble bitter taste, and forms salts with the strong mineral acids ; water readily decomposes them. On evaporating a solution of chlorine water containing traces of caffeine we get a reddish-brown spot, which acquires a beautiful violet-red color when dissolved in ammonia water. Sodium hydroxide converts theine into caffcldine carboxylic acid, C 7 H n N 4 O .- CO 2 H, which readily decomposes into CO 2 and caffeldine, C 7 H 12 N 4 O (B. 16, 2309). For other caffeine derivatives (apocaffeine, caffuric acid, caffolin) see A. 215, 261, and 228, 141. Chlorine water breaks caffeine up into dimethyl alloxan and methyl urea (p. 399). Chlorine and bromine convert caffeine into chlorcaffeine, melting at 180, and brom- caffelne, melting at 206. Zinc dust reduces both of them to caffeine. Alcoholic potash changes them to ethoxy caffeine, melting at 140. The latter is decomposed by hydrochloric acid into ethyl chloride and hydroxycaffe'ine, melting at 345. This is identical with l.^.y-trimetkyl uric acid. PC1 5 converts hydroxycaffe'ine into chlor- caffeine. Proceeding from dimethyl alloxan, i.^.y-trimethyl uric acid may be syn- thetically made, and from this caffeine through chlorcaffeine. Furthermore, the lower homologues of caffeine theobromine and theophylline can be synthesized, and by introducing methyl into them caffeine will result. This, then, is an additional synthesis of caffeine (E. Fischer, B. 30, 549) : CH 3 N CO CO CO- CH 3 .N CO Dimethyl Alloxan CH 3 .N CO CH 3 N CO CO CHN(CH 3 )CONH 2 - I | i.3.7-Trimethyl- uric A'ci udo- ^ CO C N(CH 3 V I X C CH 3 N C NH ^ i.3.7-Trimethyl Uric Acid 'lydroxycaffei'ne CO C N(CH 3 ) CH..N-C-N Chlorcaffeine CH 3 N CO CH 3 N-CO CO C N(CH 3 )\ rH -4- CO C NH i H I ii CH 3 .N-C N^ CH 3 . N - C N Caffeine Theophylline. 516 ORGANIC CHEMISTRY. Guanine, C 5 H-N 5 O, occurs in the pancreas of some animals and very abundantly in guano. Guanine is an amorphous powder, insoluble in water, alcohol and ether. It yields crystalline salts with I and 2 equivalents of acid, e. g., C 5 H 5 N 5 . 2HC1. It also forms crystalline compounds with bases. Silver nitrate gives a crystalline precipitate, C 5 H 5 N 5 O.N0 3 Ag. Nitrous acid converts guanine into xanthine. Potassium chlorate and hydrochloric acid decompose it into parabanic acid, guanidine and CO 2 (p. 41 1). 2-Amino-6.8-dioxypurin is obtained from 2-imidopseudouric acid (p. 507) and from bromguanine (B. 30, 570). HN CO , HC C Sarcine, Hypoxanthine, HC C NH\ is a constant attendant of xan- N-C -N thine in the animal organism, and is distinguished principally by the difficult solu- bility of its hydrochloride. It consists of needles not very soluble in water, but dis- solved by alkalies and acids. Silver nitrate precipitates the compound C 5 H 2 Ag 2 N 4 O -f- H 2 O from ammoniacal solutions. Dimethyl hypoxanthine splits into methyl- amine and sarcosine when it is heated with hydrochloric acid (p. 317) (B. 26, 1914). N = C.NH, Adenine, HC C NKL polymeric with hydrogen cyanide, has been isolated from beef pancreas. It also occurs in tea extract. It crystallizes in leaflets with pearly lustre. It has three molecules of water of crystallization. At 54 the salt becomes white in color, owing to loss of water. Nitrous acid converts it into hypoxanthine, and hydrochloric acid at 180-200 converts it into glycocoll, am- monia. formic acid, and CO 2 (Kossel, B. 23, 225 ; 26, 1914). Carnine, C 7 H 8 N 4 O + H 2 O, has been found in the extract of beef. It is a pow- der, rather easily soluble in water, and forms a crystalline compound with hydro- chloric acid. Bromine water or nitric acid converts carnine into sarcine. 14. TRICARBOXYLIC ACIDS. A. PARAFFIN TRICARBOXYLIC ACIDS. (a) Tricarboxylic Acids with Two or Three Carboxyls Attached to the Same Carbon Atom. Formation. (l a) By the action of the halogen fatty-acid esters on the sodium compounds of malonic esters, CHNa(CO 2 R/) 2 and alkylic malonic esters, R/. CNa- (CO 2 R / ) 2 e. g., chlorcarbonic ester, chloracetic ester, a-brompropionic ester, a-brombutyric ester, a-bromisobutyric ester, (i 1)} The tricarboxylic esters, resulting in this way from sodium malonic ester, still contain a hydrogen of the CH 2 -group of malonic ester, and can be acted upon anew with sodium and alkyl iodides. They then yield the same esters, which are obtained by starting with the monoalkylic malonic esters. (2) By the addition of sodium malonic esters to unsaturated carboxylic esters, e. g., crotonic ester (B. 24, 2888 ; C. 1897, I, 28). (3) Also by the gradual saponification of tetracarboxylic esters, containing two carboxyl groups attached to the same carbon atom, which split off carbon dioxide and yield tricarboxylic esters (B. 16,333; 2 3 6 33 '> A - 214,58). (4) By heating the best adapted ketone tricarboxylic esters (B. 27, 797), when a loss of CO occurs. TRICARBOXYLIC ACIDS. 517 Like malonic acid, these tricarboxylic acids readily break down with the elimina- tion of CO 2 . They then become succinic acids, e. g. : (CH 3 ) 2 C . CO 2 H ~ c 2 ^ (CH 3 ) a . C . CO 2 H CH . (co 2 H) 2 in, . co 2 n Isobutane-aa/3-tricarboxylic Unsym. Dimethyl Succinic Acid Acid. For the saponification of tricarboxylic esters consult B. 29, 1867. Formyl Tricarboxylic Ester, Methenyl Tricarboxylic Ester, CH(CO 2 - C 2 H-) 3 , is obtained from sodium malonic ester, CHNa(CO 2 . C 2 H 5 ) 2 , and ethyl chlorcarbonate (B. 21, R. 531) ; it melts at 29, and boils at 253. Cyanmalonic Ester, CH(CN)(CO 2 R) 2 , results from the action of cyanogen chloride upon sodium malonic ester. It volatilizes without decomposition under greatly reduced pressure. It has a very acid reaction, and decomposes the alkaline carbonates, forming salts, like CNa(CN)(CO 2 R) 2 (B. 22, R. 567). Cyanoform, CH(CN) 3 -f- CH 3 OH (?), melts with decomposition at 214. Sodium cyanoform is produced when cyanogen chloride acts upon malonitrile and sodium ethylate (B. 29, 1171). fTT fC) ("" fT Ethenyl Tricarboxylic Ester, i 5 , is obtained from sodium ethyl CH(CO 2 .C 2 H 5 ) 2 malonate and the ester of chloracetic acid. It boils at 278. Chlorine converts it into Chlorethenyl Tricarboxylic Ester, C 2 H 2 C1(CO 2 . C 2 H 5 ) 3 . This boils at 290, and when heated with hydrochloric acid, yields carbon dioxide, hydrochloric acid, alcohol, and fumaric acid; when saponified with alkalies, carbon dioxide and malic acid are the products (A. 214, 44). Unsym. Dimethyl Cyansuccinic Ester, B. 27, R. 506. Methyl a-Cyansuccinic Ester, (Cq 2 CH 3 )CH 2 CH(CN)CO 2 CH 3 , is obtained from methyl cyanacetic ester and chloracetic ester (B. 24, R. 557). CH 3 . CH . CO 2 C 2 H 5 Propane-ca/3-tricarboxylic Ester, i . boils at 270. The free acid (isomeric with tricarballylic acid) melts at 146, and breaks down into carbon dioxide and pyrotartaric acid. /-TT fO T? Propane -a/^3- tricarboxylic Ester, i ; 2 , boils at 273. CH 3 . C(CO 2 R) 2 c~* TT r^i-T r^o i? n-Butane-aa/3-tricarboxylic Ester, 2 5 ' i , boils at 278. CH(CO 2 R) 2 fTT f O T T n- Butane -a/3/3-tricarboxylic Ester, I ! , boils at 281. C 2 H 5 . C(CO 2 H) 2 Isobutane-aa/3-tricarboxylic Ester, (CO 2 R)C(CH 3 ) 2 . CH(CO 2 R) 2 , boils at 277. Compare B. 23, 648. In these formulas R represents C 2 H 5 . o-Cyanglutaric Ester (B. 27, R. 506). a.-Alkyl-a-Carboxy-glutaric Ester, see A. 292, 209; C. 1897, I, 28. $$-Dimethyl-a-Carboxy-glutaric Ester, see /3,3-Dimethyl glutaric acid, p. 454. (b} Tricarboxylic Acids with the Carboxyl Groups Attached to Three Carbon Atoms. ^ Tetra- and penta-carboxylic acids, containing one or two pairs of CO 2 H -groups attached to the same carbon atom split off carbon diox- tfe, and numerous representatives of the class have been prepared (B. 24, 307, 2889 ; 25, R. 746). Tricarballylic Acid, CH 2 . (CO 2 H) . CH(CO 2 H)CH 2 (CO 2 H), crystallizes in rhombic prisms, which dissolve easily in water, and 518 ORGANIC CHEMISTRY. melt at 162-164. It is obtained: (i) By heating tribromallyl with potassium cyanide and decomposing the tricyanide with potash; (2) by oxidizing diallyl acetic acid (p. 289); (3) by acting upon ethyl aceto-succinate with sodium and the ester of chloracetic acid, then saponifying the aceto-tricarballylic ester (see this) ; (4) by the decomposition of propane-aa/3^- and a/3/3^-tetracarboxylic ester (B. 24, 307, 2889 ; 29, 1281); (5) by the action of nascent hydrogen upon aconitic acid, C 6 H 6 O 6 (B. 22, 2921), and by the reduction of citric acid with hydriodic acid; (6) from propane-a/5^/-pentacarboxylic ester (see this), by the elimination of 2CO 2 (B. 25, R. 746); (7) by the action of caustic potash upon citrazinamide at 150 (B. 27, 1271, 3456). The acid occurs in unripe beets, and also in the deposit in the vacuum pans used in beet-sugar works. The silver salt, C 6 H.O 6 Ag ? . Calcium tricarballylate, (C 6 H 5 O 6 ) 2 Ca 3 -f- 4H 2 O, is a powder that dissolves with difficulty. The trimethyl ester, C 6 H 5 <) 6 (CH 3 ) 3 , boils at 150, under a pressure of 13 mm. The chloride, C 3 H 5 (CO.C1) 3 , boils at 140 (14 mm.) (B. 22, 2921). Anhydride acid, C 5 H 6 O 5 , melts at 131-132 (B. 24, 2890). The triamide, C 3 H 5 (CO.NH 2 ) 3 , melts at 206. The amidimide, C 6 H 8 O 3 N 2 , melts at 173 (B. 24, 600). Camphoronic Acid, aafi-Trimethyltricarballylic Add, CO 2 H CO 2 H CO 2 H CH 3 C C CH 2 , melting at 135, is formed by the oxida- CH 3 CH 3 tion of camphor and will be discussed in connection with this, as its constitution has become of prime importance in explaining the structure of camphor. Homologous Tricarballylic Acids : a-Methyl- two modifications, melting at 180 and 134; fi-Methyl- melting at 164; a-Ethyl- melting at 147-148; n-n- Propyl, melting at 151-152; a- Isopropyl-tricarballylic Add, melting at 161-162 (B. 24, 2887). aa^-Dimethyl-truarballylic Acid, three modifications ; see B. 29, 616. aj3d- Butane Tricarboxylic Acid melts at 116-120. ayt-Pentane Tricarboxylic Acid melts at 106-107 (B. 24, 284). B. OLEFINE TRICARBOXYLIC ACIDS. Aconitic Acid, * 11 same time decomposes into CO 2 and itaconic anhydride (p. 465). It is isomeric with trimethylene tricarboxylic acid (see this), and occurs in different plants ; for example, in Aconitum Napellus, in Equisetum fluviattle, in sugar cane, and in beet roots. It is obtained by heating citric acid alone or with concentrated hydrochloric or sulphuric acid (B. 20, R. 254). Aconitic acid has been synthetically made by the decomposition TETRAHYDRIC ALCOHOLS. 519 with alkali of the synthetic product resulting from the union of 2 mols. of oxalic ester and 2 mols. of acetic ester, C0 2 R' C0 2 H C0 2 R' C0 2 C 2 H 5 ^_ _ ( J ; _^ ^ (Jo (B. 24, 120) ; as well as by the break- ing-down of the body obtained from sodium malonic ester and acety- lene dicarboxylic ester (J. pr. Ch. [2] 49, 20). Aconitic acid dissolves readily in water. Nascent hydrogen con- verts it into tricarballylic acid. The calcium salt (C 6 H 3 O 6 ) 2 Ca 3 -f 6H 2 O, dissolves with difficulty. The tri- methvl es'tr, C 6 H 3 O 6 (CH 3 ) 3 , boils at 161 (14 mm.). It results from the distillation of acetyl citric trimethyl ester (B. 18, 1954), and from aconitic acid, methyl alcohol, and hydrochloric acid (B. 21, 669). The triamide, C 3 H 3 (CONH 2 ) 3 , is converted into citrazinic acid (see this) by acMs (B. 22, 1078, 3054; 23, 831). Aceconitic and Citracetic Acids, C 6 H 6 O 6 , are two acids of unknown constitu- tion. They are isomeric with aconitic acid. They result when sodium acts upon bromacetic ester (A. 135, 306). Allene Tricarboxylic Ester, CO 2 R . CH : C : C(CO 2 R) 2 , from /3-dibromacrylic ester and disodium malonic ester, melts at 107 (B. 29, R. 851). VI. TETRAHYDRIC ALCOHOLS AND THEIR OXI- DATION PRODUCTS. I. TETRAHYDRIC ALCOHOLS. Ordinary erythrol is the best known of the tetrahydric alcohols cor- responding to the four tartaric acids (p. 521). By an intramolecular compensation it, like mesotartaric acid, becomes optically inactive, and is therefore called i-erythrol. This alcohol and [d + 1] erythrol were synthetically prepared by Griner in 1893 fr m divinyl. Divinyl, or butadien (p. 99), forms an unstable dibromide, which rearranges itself at 100 into two different but stable dibromides. When these are oxidized by potassium permanganate, the one passes into the dibromhydrin (melting at 135) of ordinary or i-erythrol, while the other becomes the dibromhydrin (melting at 83) of [d - 1] erythrol. Caustic potash converts these two dibromhydrins into two buta- dien oxides, which with water yield the erythrols corresponding to i- and [d -f- 1] erythrol (B. 26, R. 932): HC . CH 2 Br (HO) . HC . CH 2 Br (HO)HC . CH 2 (OH) Hr=CH 2 ,X HC.CH 2 Br~ ^ (HO) . HC . CH 2 Br~~ ^(HOJHC. CH 2 (OH) -H 2 \_ m. p. 135 i-Erythrol HC.CH 2 Br (HO) . HC . CH 2 Br (HO)HC. CH,(OH) CH 2 BrCH(OH) ^H 2 (OH)C. CH(OH) m. p. 83 [d+lJ-Erythrol. 520 ORGANIC CHEMISTRY. i-Erythrol, Erythrite, Erythroglucin or Phycite, CH 2 (OH) . - CH(OH).CH(OH).CH 2 .OH, occurs free in the alga Protococ.us vulgaris. It exists as erythrin (orsellinate of erythrite) in many lichens and some algae, especially in Roccella Montagnei, and is obtained from these by saponification with caustic soda or milk of lime : C * H '{ (0 H C 8 H 7 3 ) 2 + 2H2 = C * H 6( H )* + 2C 8 H 8i' Erythrin Erythrol Orsellinic Acid. Like all polyhydric alcohols erythrol possesses a sweet taste. It melts at 126 and boils at 330. By carefully oxidizing erythrol with dilute nitric acid erythrose results. More intense oxidation produces erythritic acid and mesotartaric acid (p. 526). i-Nitro-erythrol, C 4 H 6 (ONO 2 ) 4 , melts at 61 and explodes violently when struck. i-Tetra-acetyl Erythrol, C 4 H 6 (OCOCH 3 ) 4 , melts at 85. i-Erythrol Dichlor- hydrin, C 4 H 6 (OH) 2 C1 2 , melting at 125, is formed from erythrol by the action of concentrated hydrochloric acid. i-Erythrol- Ether, / \ / \ , boiling CH 2 . CH . CH . CH 2 at 138, with sp. gr. 1.113 (18), is formed when caustic potash acts upon dichlor- hydrin. It is a liquid with a penetrating odor, and deports itself like ethylene oxide (p. 298). It slowly combines with water, yielding erythrol, with 2HC1 to the dichlorhydrin, and with 2CNH to the nitrile of dioxyadipic acid (B. 17, 1091). Erythrol, in the presence of hydrochloric acid, combines with formaldehyde, benzal- dehyde, and acetone, yielding : i-Erythrol-formal, C 4 H 6 O 4 (CH 2 ) 2 , melting at 96 (A. 289, 27) ; i-Erythrol-dibenzal, melting at 97 ; and i-Diacetone Erythrol, C 4 H 6 O 4 (C 3 H 6 ) 2 , melting at 56 and boiling at IO5(29 mm.) (B. 28, 2531). [d -f- 1] -Erythrol melts at 72 ; formation see above. Dibromhydrin melts at A 83 (see above) ; [d + 1] Erythrol Ether, CH 2 . CH . CH . CH, (B. 26, R. 933). \0/ Tetra-acetyl [d -f 1] Erythrol melts at 53. Nitrotertiary Butyl Glycerol, NO 2 C(CH 2 OH) 3 , melting at 158, is formed from nitromethane, formaldehyde, and some potassium bicarbonate (B. 28, R. 774). Pentaerythrol, C(CH 2 OH) 4 , melting at 250-255, has been prepared by con- densing formaldehyde and acetaldehyde with lime. See also vinyltrimethylene. Tetra-acetyl Pentaerythrol, C(CH 2 . O . COCH 3 ) 4 , melts at 84 (A. 276, 58). Penta- erythrol Dibenzal melts at 160 (A. 289, 21). Two Hexyl-erythrols have been prepared by oxidizing diallyl, CH 2 = CH . CH 2 CH 2 CH = CH 2 (p. 99). 2. TRIOXYALDEHYDES and 3. TRIOXYKETONES : Erythrose, Tetrose, is probably a mixture of a trioxy aldehyde and a trioxyketone (compare glycerose, p. 477). It is produced when erythrol is oxidized with dilute nitric acid. It yields phenylerythrosazone, C 4 H 6 O 2 (N 2 HC 6 H5) 2 , melting at 167 (B. 20, 1090). This probably is also produced from the condensation product of glycolyl aldehyde (B. 25, 2553). Methyl Tetrose, CH 3 [CHOH] 3 CHO, is formed from rhamnose- oxime and acetic anhydride. The osazone, melting at 171-174, becomes d-tartaric acid when it is oxidized with nitric acid (B. 29, 1381). 4. OXYTRIKETONES : 3-Methyl-3-heptanol-2.5.6-trion, aldol of diacetyl, CH 3 . COC(OH) . CH 3 . CH 2 . CO . CO . CH 3 , boils at 128 (i8mm.) (p. 322). DIOXYDICARBOXYLIC ACIDS. 521 5. TETRAKETONES: Tetra-acetyl Ethane, (CH 3 CO) 2 CH - CH(CO . CH 3 ) 2 , is obtained from sodium acetylacetone by means of iodine or by electrolysis (p. 323). Oxalyl Diacetone, CH 3 . CO . CH 2 .CO . CO . CH 2 . CO . CH 3 , melting at 120-121, is obtained by the action of sodium ethylate upon oxalic ester and acetone (B. 21, 1142). It forms a dipyrazole derivative with phenylhydrazine (A. 278, 294). Methenylbisacetyl Acetone, (CH 3 CO) 2 CH . CH = C(COCH 3 ), is obtained from ethoxymethylene acetyl acetone (p. 478) by the addi- tion of acetyl acetone. 6. TRIOXYMONOCARBOXYLIC ACIDS: Erythritic Acid, C 3 H 4 j 3 , erythroglucic acid, trioxybutyric acid, is pro- duced in the oxidation of erythrol, raannitol, and leevulose (B. 19, 468). It forms a deliquescent crystalline mass. Trioxyisobutyric Acid, (CH 2 OH) 2 C(OH)CO 2 H, melting at 116, is formed from glycerose and CNH (B. 22, 106). 7. DIOXYKETONE MONOCARBOXYLIC ACIDS: ay-Diethoxyaceto- acetic Ester, CH 2 (OC 2 H 6 ) i. CO . CH(O . C 2 H 5 )CO 2 C 2 H 5 , boiling at 131-132 (14 mm), results from the action of sodium ethylate upon ethoxychloracetoacetic ester (p. 482) (A. 269, 28) (p. 477)- 8. OXYDIKETONE CARBOXYLIC ACIDS: Dehydracetic Acid, (6) CO . O . C. CH 3 Methyl- (i)-acetopyronon, I , melting at 108 and boil- CH 3 .CO.CH.CO.CH ing at 269, is formed on boiling acetoacetic ester with a return cooler, on evap- orating dehydracetocarboxylic acid with caustic soda (A. 273, 186), and from acetyl chloride by the action of pyridine. It is isomeric with isodehydracetic acid (p. 496). Feist explained its constitution (A. 257, 261 ; B. 27, R. 417). Hydriodic acid converts it into dimethyl pyrone, CH 3 . C = CH . CO . CH = C . CH 3 (see this). 9. TRIKETONE-MONO-CARBOXYLIC ACIDS : The /3-phenylhydra- zone formed from sodium acetone-oxalic acid and diazobenzenechloride is a deriva- tive of afiy-triketo-n-valeric acid. It melts from 206-207 (A. 278, 285). 10. DIOXYDICARBOXYLIC ACIDS. Tartaric Acids or Dioxyethylene Succinic Acids. Tartaric acid is known in four modifications ; all possess the same structure and can be converted into one another. They are : (i) Ordinary or dextro-tartaric acid. (2) Lczvo-tartaric Add. These two are dis- tinguished from each other by their equally great but opposite molecular rotatory power. (3) Racemic Acid or paratartaric acid, or [d -f 1] tartaric acid. This is optically inactive. It can be resolved into dextro- and laevo-tartaric acids, from which it can again be recovered by their union. (4) Mesotartaric Acid, antitartaric acid, i-tartaric acid. This is optically inactive and cannot be split into other forms. The isomerism of these four acids was exhaustively con- 44 522 ORGANIC CHEMISTRY. sidered in the introduction. According to the theory of van 't Hoff and LeBel, it is attributable to the presence of two asymmetric carbon atoms in the dioxyethylene succinic acid. A compound containing one asymmetric carbon atom may occur in three modifications a dextro-form, a laevo-form, and, by union of these two, an inactive, decomposable [d -j- 1] modification. If the same atoms or atomic groups are joined to two asymmetric carbon atoms, that is, if the compound be symmetrically constructed, like dioxyethylene succinic acid, then in addition to the three modifications capable of forming a compound with one asymmetric carbon atom there arises a fourth possibility. Should, namely, the groups linked to the one asymmetric carbon atom (viewed from the point of union of the two asymmetric carbon atoms) show an opposite arrangement from that of the groups attached to the second asymmetric carbon atom, then an inactive body will result by virtue of an intramolecular compensation. The action on polarized light occasioned by the one asymmetric carbon atom is equalized by an equally great but oppositely directed influ- ence exerted by the second asymmetric carbon atom. Therefore, the four symmetrical dioxysuccinic acids can be repre- sented by the following formulas, to which must be ascribed a spacial significance as basis (p. 48) : CO 2 H COoH CCXH H *C OH HO *C H C0 2 H (i) Dextrotartaric Acid d-Tartaric acid -f 1-tartaric acid = (4) Racemic Acid. The configuration of d-tartaric acid, as represented on p. 563, fol- lows in consequence of the formation of this acid from the oxidation of methyl tetrose, the decomposition product of the rhamnoses. Historical. Scheele in 1769 showed how this acid could be isolated from argol. Kestner in 1822 discovered racemic acid as a by-product in the manufacture of ordi- nary tartaric acid, and in 1826 Gay-Lussac investigated the two acids. Very soon both he and Berzelius (1830) proved that ordinary tartaric acid and racemic acid pos- sessed the same composition, and this fact led Berzelius to introduce the term isomerism into chemical science (p. 41). Biot (1838) showed that a solution of ordi- nary tartaric acid rotated the plane of polarized light to the right, whereas the solution of racemic acid proved to be optically inactive, and was without action upon the polarized ray. Pasteur's classic investigations (1848-1853) demonstrated how racemic acid could be resolved into dextro- and Icevo-tartaric acid, and be again re-formed from them. In addition to laevo-tartaric acid, Pasteur also discovered inactive or mesotar- taric acid, which cannot be resolved. Kekule in 1 86 1 and, independently of him, Perkin, Sr., and Duppa synthesized racemic acid and mesotartaric acid from succinic acid, derived from amber, through the ordinary dibromsuccinic acid. In 1873 Jung- fleisch obtained racemic acid and mesotartaric acid from synthetic succinic acid, and also the other two tartaric acids derivable from racemic acid. Van 't Hoff in 1874 ar independently of him, Le Bel referred the isomerism of the four tartaric acids to tf presence of two asymmetric carbon atoms in symmetrical dioxyethylene succinic aci< HO *C H H *C OH H *C OH H *C OH 1 1 CO 2 H CO 2 H (2) Laevotartaric Acid (3) Mesotartaric Acid. RACEMIC ACID. 5 2 3 Kekule and Anschiitz in 1 880 and 1881 found that when racemic acid was oxidized it yielded ftimaric acid, and that inactive or mesotartaric acid gave maleic acid. The oxidant was potassium permanganate. This reaction directly linked the isomerism of the tartaric acids to the isomerism of the two unsaturated acids fumaric acid and male'ic acid. (i) Racemic Acid, Paratartaric Acid, C 4 H 6 O 4 -f- H 2 O, is some- times found in conjunction with tartaric acid in the juice of the grape, and is obtained from the mother liquor in crystallizing cream of tartar, especially in the presence of alumina. Racemic acid appears (i) in the oxidation of mannitol, dulcitol and mucic acid with nitric acid, as well as when fumaric acid (B. 13, 2150), sorbic acid, and piperic acid are oxidized by potassium per- manganate (B. 23, 2772). It is synthetically obtained (2) from glyoxal by means of prussic and hydrochloric acids (together with mesotartaric acid, B. 27, R. 749), and (3) from isodibrom- and (together with mesotartaric acid) from dibromsuccinic acid, by the action of silver oxide (pp. 452, 526); (4) together with glycollic acid (compare the pinacone formation, p. 293), when glyoxylic acid is reduced with acetic acid and zinc; (5) in addition, by heating desoxalic acid -with water to 100, when carbon dioxide is split off. Ethyl alcohol, which can be synthesized in various ways, constitutes the starting-out material for the first four syntheses. In the fifth synthesis carbon monoxide serves for that purpose. SYNTHESIS OF RACEMIC ACID. C0 2 H C0 2 H C0 2 H CO,H CH,OH CH, CH, CHBr CHBr CH j ^L .i <- i __y^ i ^t i ^c || CH 3 CH 2 CH 2 MH.~ CHBr CH C0 2 H Succinic CO 2 H Monobrom- CO 2 H CO 2 H Ord. Dibrom- Fumaric Acid succinic Acid succinic Acid Acid \ / \ / CO 2 H i ' ^r > CJN 'CHO C0 2 II CH.OH CH.OH S_ 1 CHO~ ^ C I IO CH.OH CH . OH 1 I CN CO 2 H Glyoxal Glyoxylic Acid Racemic Acid (C0 2 C 2 H 5 ) 2 (C0 2 H) 2 CO,Na C0 2 C 2 H 6 COH COH CO ->- HCO 2 Na >- 1 " CO 2 Na ^C0 2 C 2 H 6 " "*" CHOH " * CH . OH Carbon S odium Oxalate of C0 2 C 2 H 6 C0 2 H Desoxalic Acic Monoxide Formate Sodium 524 ORGANIC CHEMISTRY. Racemic acid is also produced when equal quantities of concentrated solutions of dextro- and laevo-tartaric acids are mixed (B. 25, 1566), and together with mesotartaric acid when ordinary tartaric acid is heated with water to 175. Racemic acid crystallizes in rhombic prisms which slowly effloresce in dry air. It is less soluble (I part in 5.8 parts at 15) in water than the tartaric acid, and has no effect on polarized light. It loses its crystal water when heated to Ilo. In the anhydrous condition it melts at 205-206. It foams at the same time. Potassium permanganate oxidizes it to oxalic acid and hydriodic acid reduces it to inactive malic and ethylene succinic acids. Its salts closely resemble those of tartaric acid, but do not show hemihedral faces. The acid potassium salt is appreciably more solu- ble than cream of tartar. The calcium satt, C 4 H 4 O 6 Ca -f- 4H.,O, dissolves with more difficulty than the corresponding salts of the three other tartaric acids. Acetic acid and ammonium chloride do not dissolve it. It is formed on mixing solutions of cal- cium dextro- and Isevotartrates. Barium salf, C 4 H 4 O 6 Ba-f 2^H 2 O or 5H 2 O (A. 292,311). Decomposition of Racemic Acid. When Pasteur was study- ing racemic acid he discovered methods for the decomposition of optically inactive bodies into their optically active components. These were briefly considered in the introduction (p. 68) : (i) Penicillium glaucum destroys the dextro-tartaric acid growing in a racemic acid solution, leaving the 1-tartaric acid undisturbed. (20) From a solution of sodium ammonium racemate unaltered salt, without hemihedral faces, separates above -j-28 (B. 29, R. 112). When the crystallization takes place below -{-28, large rhombic crys- tals form. Some of these show right, others left hemihedral faces. Removing the similar forms, or by testing a solution of the crystals with a solution of calcium dextro-tartrate (A. 226, 197), we discover that the former possess right-rotatory power and yield common tartaric acid, whereas the latter yield the laevo-acid. (zb) From a solution of cinchonine racemate the first crystallization consists of the more sparingly soluble Isevotartrate. If only half as much cinchonine, as is necessary for the production of the acid salt, be introduced, then two-thirds of the calculated quantity of cincho- nine laevo-tartrate will separate (B. 29, 42). Quinicine dextrotartrate is the first to crystallize from a solution of quinicine racemate. Esters of Racemic Acid: The dimethyl ester melts at 85 and boils at 282. It is produced from racemic acid, methyl alcohol, and HC1. It is obtained pure by distillation under reduced pressure. It can be made by fusing together the dimethyl ester of dextro- and laevo-tartaric acids. In vapor form the ester of racemic acid dis- sociates into the dimethyl ester of the dextro- and laevo-tartaric acids (B. 18, 1397; 21, R. 643). Diacetyl Racemic Anhydride, (C 2 H 3 O 2 ).,C 4 H 2 O 3 , melts at 122-123 (B. 13, 1178). Dimethyl Diacetyl Racemic Ester, (C 2 H 3 O 2 2 C 4 H 2 O 4 (CH 3 ) 2 , melting at 86, results from the action of acetyl chloride upon the dimethyl ester, and upon evaporat- ing the benzene solution of the dimethyl 1- and d-diacetyl tartaric esters. Nitrile Diacetylpyroracemic Acid, CH 3 . CO . O .CH(CN) . CH(CN)O . COCH 3 , melting 97, is produced together with the nitrile of diacetyl mesotartaric acid, when acet anhydride acts upon the liquid portion of the additive product resulting from CN1 and glyoxal in alcohol (B. 27, R. 749). ORDINARY TARTARIC ACID. 5 2 5 Imides : Methyl-, ethyl-, and phenyl imides melt at 157, 179, and 235 (B. 29, 2719). The anil of diacetylracemic acid melts at 94. It results when PCI 5 acts upon the anilic acid, and when the anils of d- and 1-diacetyltartaric acids combine (privately communicated by Anschiitz and Reitter). (2) Dextro-rotatory or Ordinary Tartaric Acid (Acidum tartaricuni] is widely distributed in the vegetable world, and occurs principally in the juice of the grape, from which it deposits after fermentation in the form of acid potassium tartrate (argol). It results on oxidizing saccharic acid and milk sugar with nitric acid. Common tartaric acid crystallizes in large monoclinic prisms, which dissolve readily in water (i part in 0.76 parts at 15) and alco- hol, but not in ether. Its solution turns the ray of polarized light to the right. It melts at 167-170 (B. 22, 1814), when rapidly heated. When it is heated with water to 165 it changes mainly to mesotar- taric acid; at 175 the racemic acid predominates. It also forms racemic acid when it is brought together with a concentrated solution of 1-tartaric acid. Pyroracemic and pyrotartaric acids are products of its dry distillation. When gradually oxidized, d-tartaric acid becomes dioxyfumaric acid (P- 5 2 7)> dioxytartaric acid, and tartronic acid (p. 485); stronger oxidizing agents decompose it into carbon dioxide and formic acid. Hydriodic acid reduces it to d-malic and ethylene succinic acids. d-Tartaric acid is applied in dyeing or coloring, as an ingredient of effervescing powders, and as a medicine. Nearly all of its salts meet with extended uses. Tartrates. The neutral potassium salt, C 4 H 4 K 2 O 6 -)- ^H 2 O, is readily soluble in water ; from it acids precipitate the salt C 4 H-KO 6 , which is not very soluble in water, and constitutes natural tartar-tf ;>/ (Cremor tartari}. Potassium-Sodium Tartrate. C 4 H 4 KNaO fi -f- 4H 2 O (Seignette's salt], crystallizes in large rhombic prisms with hemihedral faces. The sodium-ammonium salt, C 4 H 4 KNaO 6 -|- 4H 2 O, is obtained from sodium-ammonium racemate. The calcium salt, C 4 H 4 CaO 6 -f- H 2 O, is pre cipilated from solutions of neutral tartrates, by calcium chloride, as an insoluble, crystalline powder. It dissolves in acids and alkalies, and is reprecipitated as a jelly on boiling a reaction serving to distinguish tartaric from other acids. See also calcium racemate. The neutral If ad salt, C 4 H 4 PbO 6 , is a curdy precipitate. Tartar Emetic. Potassio- antimony I Tartrate, C 4 H 4 (SbO)KO 6 -f ^H 2 O, or C 4 H 4 O 6 : SbOK -f- ^H 2 O, or CO 2 K[CHOH] 2 COOSbSb . OCO[CHOH] 2 . - COOK -f H 2 O (B. 16, 2386), is prepared by boiling cream of tartar with antimony oxide and water. It crystallizes in rhombic octahedra, which slowly lose their water of crystallization on exposure and fall to a powder. It is soluble in fourteen parts of water at 10. Its solution possesses an unpleasant metallic taste, and acts as a sudorific and emetic. See B. 29, R. 84 ; 28, R. 463, for the corresponding arsenic compound. d-Dextro-tartaric Acid Esters (compare racemic esters). To obtain the esters of tartaric acid, C 2 H 4 O 2 (CO 2 R) 2 , dissolve the acid in methyl or ethyl alcohol, con- duct hydrochloric acid gas through the solution, and distil the liquid under dimin- ished pressure. PC1 5 converts them into esters of chlormalic acid (p. 489) and chlor- fumaric acid. The esters constitute the first homologous series of optically active substances, which were investigated along the line of rotation of the plane of polar- 526 ORGANIC CHEMISTRY. ized light (Anschiitz and Pictet, B. 13, 1177 ; compare C. 65, 996; B. 27, R. 511, 621, 725, 729; B. 28, R. 148). The dimethyl ester melts at 48 and boils at 280 (760 mm.), [a] D = -j- 2.142 (20). The diethvl ester boils at 280 (760 mm.), [a] D = -f 7.659 (20). The di-n-dipropyl ester boils at 303 C. (760 mm.), [a] D = -}- 12.442 (20). Diacetyl-d-iartaric Anhydride, (C 2 H 3 O 2 ) 2 C 4 H 2 O 3 , melts at 125-129. Diacetyl Dimethyl Ester melts at 103. Diacetyl Tartaric Dianilide melts at 214 (A. 279,' 138). Diacetyl-d-tartranil ; see the anil of diacetyl pyroracemic acid, p. 524; other imides, B. 29, 2710. By dissolving pulverized tartaric acid in concentrated nitric acid and adding sul- c*r\ pj phuric acid, so-called Nitro-tartaric Acid, C 2 H 2 (O . NO 2 ) 2 <^ 2 J results. It de- composes in aqueous solution with the formation of dioxytartaric acid (p. 527). CO 2 H . C(OH) 2 C(OH) 2 CO 2 H, which further breaks down into CO 2 and tartronic acid. (3) Laevo-Tartaric Acid is very similar to the dextro-variety, also melts at 167-170, and only differs from it in deviating the ray of polarized light to the left. Their salts are very similar, and usually isomorphous, but those of the laevo-acid exhibit opposite hemihedral faces. The dimethyl ester has the same melting and boiling points as the dimethyl ester of d-tartaric acid (see above); also compare racemic acid esters (p. 524). In the description of racemic acid the method by which 1-tartaric acid could be obtained from it was exhaustively considered (p. 524). In concentrated solution it combines with d-tartaric acid and yields racemic acid. (4) Inactive Tartaric Acid, Mesotartaric Add, Antitartaric Add, is obtained when sorbine and erythrol are oxidized with nitric acid, or (together with racemic acid) when dibromsuccinic acid is treated with silver oxide (p. 523) and male'ic acid and phenol with potassium permanganate (B. 24, 1753). It is most readily prepared by heating common tartaric acid with water to 165 for two days. It contains a molecule of water of crystallization. Calcium Salt, C 4 H 4 O 6 Ca + 3H 2 O (A. 226, 198). Barium Salt, C 4 H 4 O 6 -f H a O (A. 292, 315). Dimethyl Ester melts at III . Diethyl Ester melts at 54, and boils at 156 (14 mm.) (B. 21, 517). Mesotartaronitrile, CN . CH(OH) . CH- (OH)CN, melts with decomposition at 131. It is produced by the addition of prus- sic acid to glyoxal, dissolved in alcohol. Diacetylmesotartaronitrile melts at 76 (B. 27, R. 749). Diamidosuccinic Acids, CO 2 H . CH(NH 2 ) . CH(NH 2 ) . CO 2 H, are formed when the diphenylhydrazone of dioxosuccinic acid (p. 528) is reduced with sodium amal- gam. The one acid corresponds to mesotartaric acid (see above), the other to race- mic acid (p. 523). This has been proved by changing the amido-acids into these acids (B. 26, 1980). Dianilinosuccinic Ester, CO 2 C 2 H 5 . CH(NHC 6 H B ) . CH(NHC 6 H 5 ) . CO 2 C 2 Hg, melting at 149, is obtained from dibrom- and isodibrom-succinic ester and alcoholic aniline heated to 100 (B. 27, 1604). /-ITT (*C) p TJ Imidoethyhuccinic Acid, NH< i "225^ me j t j n g at ^go^ j s obtained by CH . CO,H the action of hydrochloric acid upon imidosuccinamic ester, the product resulting from the action of alcoholic ammonia upon bromsuccinic ester (B. 25, 646). DIKETONE D1CARBOXYI.IC ACIDS. 527 Azinsuccinic Ester, (CO 2 C 2 H 5 ) 2 . C 2 H 2 . X 2 . C J H. ) (CO 2 r 2 H 5 ), is obtained from diazoacetic ester; an isonieric ester is obtained from diazosuccimc ester (B. 29, 763). C 1 CH 3 ).CO 2 H Oxycitracomc Acid, O< i , decomposes at 162. It is formed when CH . CO 2 H a-chlorcitranialic acid, melting at 139, the addition product of C1OH and citraconic aci4, is treated with caustic alkali. Hydrochloric acid changes it to /3-chlorcitramalic acid, melting with decomposition at 162 (A. 253, 87). CH 3 .C(OH).CO 2 U Dimethyl Racemic Acid, ^ C(OH) co H + H 2' is P r d u ced (i) by the reduction of pyroracemic acid (B. 25, 397), and (2) when hydrocyanic and hydro- chloric acids act upon diacetyl (p. 322). The acid melts at 177-178 (B. 22, R. 157). al-Dioxyglutanc Acid, CO 2 H . CH(OH) . CH(OH) . CH 2 . CO 2 H, melting from 155-1^6, is obtained from the addition product of glutaconic acid (B. 18, 2517). ; -Dioxyglutaric Acid, CO 2 H . CH(OH) . CH 2 . CH(OH) . CO 2 H, is formed from dioxypropenyl tricarboxylic acid, the oxidation product of isosaccharin (p. 537) through the elimination of CO 2 (B. 18, 2516). ; Dtoxy-dimethyl Glularic Acids, C( ^>C(OH) . CH 2 . C(OH)<^ H - The acid, melting at 98, has been obtained from ether in enantiomorphous crystals. The second acid readily changes to a lactonic acid, melting at 189-190. This yields a dilactone, melting at 104-105 and boiling at 235, when it is heated. These acids are produced when acetyl acetone is treated with CNH (B. 24, 4006; compare B. 25,3221). ay-Dioxy-afty-trimethyl Glutaric Acid see B. 28, 2940. Dimelhyloxyadipic Acids have been prepared from acetonyl acetone and CNH (B. 29, 819). Cineolic Acid, C 10 H 16 O 5 , the anhydride of a dioxydicarboxylic acid resembling ethylene oxide, will be discussed later under cineol. CH 2 . CH 2 . CH 2 CH 2 . CH 2 . CH 2 Di-u-oxypropylmalonic Lactone, \ >C< I , melting at 1 06, is obtained from diallylmalonic acid (p. 467) by the action of hydrobromic acid (A. 216, 67). Dioxyolefine Dicarboxylic Acid. The simplest possible acid of this class appears to be formed when tartaric acid is oxidized with hydrogen peroxide in the sunlight and in the presence of a small quantity of a ferrous salt. It may be called dioxyfumaric acid, CO 2 H . C(OH) : C(OH) . CO 2 H -f 2H 2 O. ,Diacetyl-dioxyfumaric acid melts at 98 (Fenton, B. 29, R. 547). II. OXYKETONE DICARBOXYLIC ACIDS: Ethoxyl - oxalo - acetic Ester, CO 2 C 2 H 5 . CO . CH(O . C 2 H 5 )CO 2 C 2 H 5 , boils at 155 (17 mm.). It is obtained from oxalic ester and ethyl glycollic ester (B. 24, 4210). /CH CO 2 C 2 H 5 Nitrilosuccinic Diethyl Ester, N-^ || , melting at 154 (40 mm.), is \V_^ V_^ (^/2 l^/q -I A K formed from the silver salt of y-oximidosuccinic ester and ethyl iodide with subse- quent distillation (B. 23, R. 561 ; 24, 2289). 12. DIKETONE DICARBOXYLIC ACIDS. C(OH) 2 . CO 2 H Dioxytartaric Acid, I . It melts with decomposition at 98 (B. C(OH) 2 . CO 2 H 22, 2015). It is obtained when protocatechuic acid, pyrocatechin, and guaiacol, in ethereal solution, are acted upon with N 2 O 3 . It was formerly regarded as carboxy- tartronic acid, C(OH) . (CO 2 H) 3 . Its formation from the benzene derivatives just 528 ORGANIC CHEMISTRY. cited is proof for the assumption that in benzene one carbon atom is combined with three other carbon atoms. However, Kekule removed the basis from this assumption when he showed that the body supposed to be carboxytartronic acid could also be made from nitrotartaric acid by the action of an alcoholic solution of nitrous acid, and then by reduction be converted into racemic and mesotartaric acids. He there- fore named it dioxytartaric acid, for it sustains the same relation to tartaric acid that glyoxylic acid bears to glycollic acid, and mesoxalic acid to tartronic acid (A. *22i, 230). Glyoxal is formed when sodium dioxytartrate is acted upon with sodium bisulphite. The sodium salt, C 4 H 4 Na 2 O 8 -f- 2H 2 O, is a sparingly soluble crystalline powder. The dioxytartaric esters are not known. Dioxy-oxosuccinic Diethyl Ester, CO 2 - C 2 Hg . C(OH) 2 CO . CO 2 C 2 H 5 , is, however, known. It consists of colorless crystals melting at Il6-ll8. They are produced on adding water to dioxosuccinic diethyl ester, CO 2 C 2 H 5 . CO . CO. CO 2 C 2 H 5 , boiling at 232-233 (760 mm.), 115-117 (13 mm.); sp. gravity 1.1896 (20). The distillation is conducted under reduced pressure. Hydrochloric acid acting upon sodium dioxytartaric acid suspended in alcohol produces the dioxosuccinic diethyl ester. It is a thick liquid with an orange- yellow color ( B. 25, 1975) (compare a-diketones, p. 321). When it is boiled with a return cooler CO splits off, and oxomalonic ester (p. 498; and oxalic ester result (B. 27, 1304). Two isomeric dioximes of dioxosuccinic acid are known (B. 24, 1215). Furazan Carboxylic Acid is the oxime anhydride of the dioxime. Diojcimidohyperojcid-succinic Acid, i l , is an unstable oil, formed by oxidizing isonitroso-acetic and OIN '. \^ . v^Oo^i acetoacetic esters (p. 368) with nitric acid (B. 28, 1213). Dioxosuccinic acid also yields pyrazolonopyrazolon, a double lactazam, amono- phenylhydrazone and a phenylosazone. The lactazam corresponding to the latter compound is the parent substance of a yellow dye, Tartrazine, which will be more fully described under the pyrazolons (A. 294, 219). Three isomeric osazones : o-, melting at 121 ;/?-, melting at 136-137; and y-, melting at 175, of dioxosuccinic diethyl ester are known. The a- body, when in solution, gradually changes to the /3-compound. Iodine or SO 2 will accelerate the conversion. All these osazones enter the pyrazolon formation very readily. Oxalo-diacetic Acid, Ketipic Acid, CO 2 H . CH 2 . CO . CO. CH 2 . CO 2 H, is precipitated in the form of a white insoluble powder on adding concentrated hydro- chloric acid to the ester. It breaks down on heating into 2CO 2 and diacetyl (p. 322). Oxalo-diacetic Ester, Ketipic Ester, CO 2 C 2 H 5 . CH 2 . CO . CO . CH 2 . CO 2 C 2 H 5 , is produced like oxalacetic ester (p. 499) by the action of sodium upon a mixture of oxalic ester with 2 mols. of acetic ester (B. 20, 591) ; also from oxalic ester and chlor- acetic ester by the action of zinc (B. 20, 202). It consists of leafy crystals melting at 77. Ferric chloride imparts an intense red color to its alcoholic solution, chlorine and bromine convert the ester into tetrachlor- and tetrabrom-oxaldiacetic ester. The first is called tetrachlordiketo-adipic ester, and is also produced when chlorine acts upon dioxy-quinone dicarboxylic ester (B. 20, 3183). The osazone of oxaldiacetic ester may be converted into di-l-phenyl-^.^-bispyrazolon (B. 28, 68). Oxal-laevulinic Ester (B. 21, 2583). Diacetosuccinic Acid, C 8 H 10 O 6 . Its ethyl ester is produced by electrolysis and by the action of iodine upon sodium acetoacetic ester (A. 201, 144; B. 28, R. 452). CH 3 . CO . CHNa . CO 2 R CH 3 . CO . CH . CO 2 R CH 3 . CO . CHNa . CO 2 R + l * ~ C H 3 . CO CH . CO 2 R "* It crystallizes in thin plates, melting at 88. It exists also in a liquid (fi-) modifi- cation, and a y-form melting at 68 (A. 293, 86). It is very unstable and undergoes various transformations, correspond! rg to its y-diketone nature (with the atomic OXYTRICARBOXYLIC ACIDS. 529 grouping CO . CH . CH . CO, p. 324). Thus, when heated or acted upon by acids, it yields carbopyrotritartaric ester (a derivative of furfurol). Pyrrol derivatives result when it is acted upon with ammonia and amines. This reaction will serve for the detection of diaceto-succinic ester (B. 19, 14). Phenylhydrazone produces bispyra zolon derivatives (A. 238, 168). Sodium hydroxide causes the ester to break down into 2CO 2 , and acetonyl acetone (P- 324) CH 3 . CO . CH . CO 2 H a/J-Diaceto-glutaric Acid, i . Its diethyl ester is ob- CH 3 . CO . CH . CH 2 CO 2 H tained from acetoacetic ester and /J-laevulinic ester (p. 381). Being a y-diketone compound, it unites with ammonia and forms a pyrrol-derivative (B. 19, 47). /~TJ r*(~} f^i-T c*(~\ c* TT ay-Diaceto-glutaric Ester 3 ' _->CH 2 2 2 5 , is formed from form- Crl 3 . L-U . Crl LU 2 L, 2 H 5 aldehyde and acetoacetic ester in the presence of small quantities of a primary or secondary amine (Knoevenagel, A. 288, 321). It passes readily into a tetrahydro- benzene derivative. The /3-alkyl-ay-diaceto-glutaric esters prepared from the hom- ologous aldehydes deport themselves in a similar manner. CH 2 . CH(CO . CH 3 ) . CO 2 H arf-Diaceto-adipic Acid, | . Ethylene bromide acting CH 2 . CH(CO . CH 3 ) . CO 2 H upon two molecules of sodacetoacetic ester, forms its diethyl ester. Phenylhydrazine converts it into a bispyrazolon derivative (B. 19, 2045). Diaceto-dimethyl Pimelic Acid (B. 24, R. 729). CH 2 . CO . CH. . CH 2 . CO 2 H Dilaevulinic Acid, ^.7-Decandion Diacid, \ , results CH 2 . CO . CH 2 . CH 2 . CO 2 H when alcoholic hydrochloric acid acts upon (J-furfural-lsevulinic acid (A. 294, 167). Iodine converts disod - diaceto - succinic ester into diaceto - fumaric ester, CH, . CO . C . CO 2 R II , melting at 96. CHg . CO . C . COjR f^f^ p TT pp. p TT Methenylbisacetoacetic Ester, ^ 2 (5}>CH CH = C C(OH)CN -> C(OH).C0 2 H > C(OH).CO 2 H ^ C(OH).CO 3 H CH 8 C1 CH 2 C1 CH 2 C1 CH 2 .CN CH 2 .CO 2 H 45 530 ORGANIC CHEMISTRY. Citric acid is also obtained by the action of prussic and hydro- chloric acids upon acetone dicarboxylic acid. Properties. Citric acid crystallizes in large rhombic prisms, which dissolve in 4 parts of water of 20, readily in alcohol and with diffi- culty in ether. The aqueous solution is not precipitated by milk of lime when cold, but on boiling the tertiary calcium salt separates. This is insoluble, even in potash (see Tartaric Acid). Transpositions. When heated to 175 citric acid decomposes into aconitic acid (p. 518). Rapidly heated to a higher temperature aconitic acid breaks down into water and its anhydride acid, which changes to CO 2 and itaconic anhydride, and the latter in part to citra- conic anhydride. Another portion of the citric acid loses water and CO 2 , becoming thereby acetone dicarboxylic acid, which immediately splits into 2CO 2 and acetone : CH.C0 2 H CH 2 II II ' C.CO > C.CO C(OH)C0 2 H .CO,H AH,. :.co It breaks up into acetic and oxalic acids when fused with caustic pot- ash, and by oxidation with nitric acid. Acetone dicarboxylic acid (p. 521) is produced when citric acid is digested with concentrated sulphuric acid. Salts. Being a tribasic acid it forms three series of salts, and also two different mono- and two different dialkali salts (B. 26, R. 687). The calcium sail, (C 6 H 5 O 7 ) 2 Ca3 -f- 4H 2 O, is precipitated on boiling. Esters : The trimethyl ester melts at 79 and boils at 176 (16 mm.). Trimethyl Acetocitric Ester, boiling at 171 (15 mm.), decomposes when distilled at the ordinary pressure into acetic acid and aconitic ester (B. 18, 1954). Acetocitric anhydride, melting at 121 (B. 22, 984), breaks down when distilled at the ordinary pressure into CO 2 , acetic acid and citraconic anhydride. Citramide, C 8 H 4 (OH)(CO . NH 2 ) 3 . When digested with hydrochloric or sulphuric acid it is condensed to citrazinic acid (dioxypyridine carboxylic acid) (B. 17, 2687; 23, 831 ; 27, R. 83). Isocitric Acid, CO 2 H . C(CH 3 )(OH) . CH(CO 2 H) . CH 2 . CO 2 H, is obtained from acetosuccinic ester by means of prussic and hydrochloric acids. When liberated from its salts it immediately passes into a y-lactone dicarboxylic acid (A. 234, 38). Cinchonic Acid, butenyl-c?-oxy-<7/3y-tricarboxylic lactone, melting at 168 234, 85 ; B. 25, R. 904), is produced When sodium amalgam acts upon cinchome onic acid or /ty-pyridine dicarboxylic acid. When heated to 168 it breaks do\ into CO 2 and pyrocinchonic anhydride (p. 466) : N CH == C . CO 2 H O CH 2 CH . CO 2 H CH 3 .C.CO CH CH = C.C0 2 H~~ ^CO CH 2 CH . CO 3 H~ ^ CH, C.CO Cinchomeronic Acid Cinchonic Acid Pyrocinchonic Anhydride. PARAFFIN TETRACAKBOXVLIC ACIDS. 531 14. KETONE TRICARBOXYLIC ACIDS. CO 2 . C 2 H 5 . CO . CH . CO 2 C 2 H, Oxal-succinic Ester, i ,boilingat 155 (I7mm.), L/rl 2 . L,U 2 v^ 2 rl 5 is formed when sodium ethylate acts upon oxalic ester and succinic ester. When it is heated alone under ordinary pressure, it breaks down into CO and ethenyl tricar- boxylic ester (p. 517) (B. 27, 797). Being a /3-ketonic acid derivative, its ester yields a pyrazolon compound with phenylhydrazine. Ferric chloride imparts a red color to its alcoholic solution. It breaks down when heated above 150 into CO and ethane tricarboxylic ester (B. 27, 797; A. 285, i). a-Acetotricarballylic Ester, CH 3 . CO . CH(CO 2 C 2 H 5 )CH(CO 2 C 2 H 5 )CH 2 - (CO 2 C 2 H 5 ), boiling at 175 (9 mm.), is obtained from chlorsuccinic ester and sodium acetoacetic ester (B. 23, 3756). /3-Acetotricarballylic Ester, CO 2 . C 2 H 5 . CH 2 . C(COCH 3 )(CO 2 C 2 H 5 ) . CH 2 . - CO 2 C 2 H 5 , boiling at 190 (16 mm.), is formed from sod-acetosuccinic ester and chlor- acetic ester, and as a by-product in the preparation of acetosuccinic ester (A. 295, 94) ; see also /3-acet-glutaric acid, p. 502. 15. TETRACARBOXYLIC ACIDS. A. PARAFFIN TETRACARBOXYLIC ACIDS. Formation. (i) By the action of iodine upon sodium malonic ester. (20) From the sodium derivatives of malonic esters and alkylen dihalogenides or halogen malonic esters. (2b] From sodium tricarboxylic esters and halogen acetic esters. (3) By the addition of sodium malonic esters to the esters of unsaturated dicar- boxylic acids, etc. Usually they are only known in the form of their esters. Sym. Ethane Tetracarboxylic Acid, Dimalonic Add, (CO 2 H) 2 CH CH (COOH) 2 , melts at 167-169, and heated to higher temperatures becomes ethylene succinic acid. It is obtained from its ester by means of sodium hydroxide (B. 25, 1158). The ethyl ester, melting at 76 and boiling with decomposition at 305, is produced by electrolysis (B. 28, R. 450) ; by the action of chlormalonic ester and of iodine upon sodium malonic ester, and by heating dioxalosuccinic ester (see this). Caustic potash saponifies it to ethane tricarboxylic acid with the elimination of CO 2 (P- 5*7)- See B. 28, 1722, for the dihydrazide. Sodium ethylate converts ethane tetracarboxylic ester into a disodium derivative, which yields tetrahydronaphthalene-tetracarboxylic ester (B. 17, 449) with o-xyly- lene bromide, C 6 H 4 (CH 2 Br) 2 . Ethyl Ethane Tetracarboxylic Ester, B. 17, 2785. Dimethyl Ethane Tetracarboxylic Ester, B. 18, 1202; 28, R. 451. Diethyl Ethane Tetracarboxylic Ester, B. 21, 2085 ; 28, R. 452. Alkylen Dimalonic Acids. The following acids for practical reasons are in- cluded in this class : methylene-, ethylene-, and trimethylene-dimalonic acids. Their ethyl esters are produced when methylene iodide, ethylene bromide, and trimethylene bromide act upon sodium malonic esters. ^-Propane Tetracarboxylic Ester, Methylene Dimalonic Ester, Dicarboxy- glutaric Ester, CH 2 <^ -o 2 r? 5 H is obtained by the condensation of formic U I \\ v^L^ 2 v_x 2 H 5 ) 2 aldehyde or methylene iodide (B. 22, 3294; 27, 2345) with two molecules of malonic ester, and by the action of zinc dust and acetic acid upon /3-propylene tetracarboxylic acid (B. 23, R. 240). It boils at 240 under loomm. pressure. Ethidene Dimalonic Ester, CH, . CH<^ 2 &2 5 } 2 , i s produced by the L,M(UU 2 C 2 tl5) 2 union of ethidene malonic ester (see this) and sodium malonic ester. 532 ORGANIC CHEMISTRY. Ethylene Dimalonic Ester, Butane Tetracarboxylic Ester, CH 2 .CH(C0 2 C 2 H 5 ) 2 , is formed together with a-trimethylene dicarboxylic ester CH 2 . CH(C0 2 C 2 H 5 ) 2 when ethylene bromide acts upon sodium malonic ester (B. 19, 2038). See, further, trimethylene- 1. 1 -dicarboxylic acid and hexamethylene- 1.1-3. 3-tetra- carboxylic ester. Alkyl Butane Tetracarboxylic Ester, B. 28, R. 300, 464. Trimethylene Dimalonic Ester, Pentane - Tetracarboxylic Acid, CH 2 < CH 2 .CH(C0 2 C 2 H 5 ), CH 2 .CH(C0 2 C 2 H 5 ); , is formed, together with tetramethylene dicarboxylic 2 v (see this) in the action of trimethylene bromide upon two molecules of sodium malonic ester. See also hexamethylene-i.l-3.3-tetracarboxylic ester. It is noteworthy that the disodium derivatives of the alkylen dimalonic esters are converted by the action of bromine or iodine, or of CH 2 I 2 and CH 2 Br. CH 2 Br, into cycloparaffin tetracarboxylic esters. The alkylen dimalonic acids split off two CO 2 groups and yield alkylen diacetic acids; so, too, the cycloparaffin tetracarboxylic acids, obtained from the alkylen dimalonic acids, yield cycloparaffin dicarboxylic acids : CH(C0 2 C 2 H 5 ) 2 CH 2 < ' CH(C0 2 C 2 H 5 ) 2 Methylene Dimalonic Acid CH 2 .CH(C0 2 C 2 H 5 ) 2 CH 2 .CH(C0 2 C 2 H 5 ) 2 ~~ Ethylene Dimalonic Acid CH 2 .CH(C0 2 C 2 H 5 ) 2 j Trimethylene Tetracar- boxylic Acid CH 2 .C(C0 2 C 2 H 5 ) 2 _ " CH 2 .C(C0 2 C 2 H 5 ) 2 Tetramethylene Tetracar- boxylic Acid CH CH.CO,H -CH 2 < CH . C0 2 H Trimethylene Dicarboxylic Acid. CH 2 . CH . C0 2 H CH 2 . CH . CO 2 H Tetramethylene Dicarboxylic Acid. CH 2 CH . CO,H CH 2 .CH(CO 2 C 2 H 5 ) 2 Trimethylene Dimalonic Acid CH CH 2 .C(C0 2 C 2 H 5 ) 2 -CH 2 < | _^C CH 2 . C(CO,C 2 H 5 ) 2 CH 2 CH . CO 2 H Pentamethylene Tetracar- Pentamethylene Dicarboxylic boxylic Acid Acid. Sodium and ethyl chloracetate change ethenyl tricarboxylic ester into the ester of Propane-a/3/3y-tetracarboxylic Acid, C(CO 2 H) 2 < ^ 2 ' ^Q 2 [J , Malondiacetic acid, which boils with slight decomposition at 295 (200 mm.). The free acid is obtained by saponifying the ester. It melts at 151 and decomposes into carbon dioxide and tricarballylic acid. Tetracarboxylic acids are formed by the addition of sodium malonic and sodium alkyl-malonic esters to the olefine dicarboxylic esters. These acids lose CO 2 and become tricarballylic acids (p. 517) (J. pr. Ch. [2], 35, 349; B. 24, 311; 24, 2889; 26, 364). Propane-aa/3y-tetracarboxylic Ester, (CO 2 C 2 H 5 ) 2 CH . CH(CO 2 C 2 H 5 ) . CH 2 - CO 2 C 2 H 5 , boiling at 203-204, is obtained (i) from fumaric ester and sod-malonic ester (compare ethidene dimalonic ester) ; (2) from monochlorsuccinic ester and sodium malonic ester (B. 23, 3756; 24, 596). Tricarballylic acid is produced when the ester is saponified with alcoholic potash. Butane-a/3yJ-tetracarboxylic Acid, CH 2 (CO 2 H)CH(CO 2 H)CH(CO 2 H)CH 2 . - (CO 2 H), melting at 244, is prepared from a-malon-tricarballylic acid. Its dian- hydride melts at 173 (B. 26, 364; 28, 882). PENTAHYDRIC ALCOHOLS, PENTITES. 533 B. UNSATURATED TETRACARBOXYLIC ACIDS. C(C0 2 C 2 H 5 ) 2 Ethylene or Dicarbon-Tetracarboxylic Ester, 11^ , is obtained by C(CO 2 C 2 H 5 ) ? letting sodium ethylate act upon chlormalonic ester, and by the action of iodine upon disodium malonic ester (B. 29, 1290). It melts at 58, and boils at 325. CH.C0 2 H " Propylene-aa/ty-tetracarboxylic Acid, C 7 H 6 O 8 = C / CO 2 H Its ethyl \CH(CO,H) 2 . ester is formed from brommaleic ester and sodium malonic ester. The acid contains two molecules of water of crystallization. These escape at 100. The anhydrous acid melts at 191, with decomposition into CO 2 and pseudo-aconitic acid melting at 145-150. Propylene-aoyj-tetracarboxylic Ester, CH(CO 2 H) 2 . CH : C(CO 2 C 2 H 5 ) 2 , di- carboxyl-glutaconic ester, results from the interaction of sodium malonic ester and chloroform. See also ethoxymethylene malonic ester (p. 494). When saponified with hydrochloric acid it yields glutaconic acid. Sodium amalgam converts it into dicarboxyl-glutaric ester. It splits off alcohol and then condenses to S-lactone, melt- ing at 93 (B. 22, 1419 ; 26, R. 9) : C0 2 . C 2 H 5 . CH . CO. . C 2 H 5 C0 2 C 2 H 5 . C = C OC 2 H 6 5 . C -- CO C0 2 . C 2 H 6 . C . COOC 2 H 5 C0 2 . C 2 H When it is heated with caustic potash it decomposes into formic and malonic acids. Glutaconic acid is also produced (p. 467) (B. 27, 3061; C. 1897, I, 29, 229). When amidines, hydrazine, and hydroxylamine act upon it, malonic ester splits off, and cyclic derivatives of oxymethylene malonic acid result (p. 494). Allene Tetracarboxylic Ester, (CO 2 C 2 H 5 ) 2 . C : C : C(CO 2 C 2 H 6 ) 2 , from di- sodium- and dichlormalonic esters, melts at 94 (B. 27, 3374). VII. THE PENTAHYDRIC ALCOHOLS OR PEN- TITES AND THEIR OXIDATION PRODUCTS. i. PENTAHYDRIC ALCOHOLS, PENTITES. One of these occurs in nature ; all the rest have been obtained by the reduction of the corresponding aldopentoses with sodium amalgam. Their constitution follows from that of the aldopentoses from which they have been prepared. The simplest pentite, C 5 H 7 (OH) 5 = CH 2 - OH . CH(OH) . CH(OH) . CHOH . CH 2 OH, can have five theoretical modifications, because in the formula two asymmetric carbon atoms are present, and they are separated by a non-asymmetric carbon atom. There are two optically active modifications, one of which is known as 534 ORGANIC CHEMISTRY. 1-arabite. There is also an inactive modification, produced by the union of the preceding forms, and which can be split into them. Finally, there exist two optically inactive modifications due to an intramolecular compensation. These can not be resolved. They are xylite and adonile. The pentites are oxi- dized to pentoses by bromine and soda (B. 27, 2486). Compare p. 562 for the stereo- chemical constitution of the pentites. 1. 1-Arabite, C 6 H 7 (OH) 5 , melting at 102, is lasvorotatory after the addition of borax to its aqueous solution. It is produced by the reduction of ordinary or 1-arabin- ose (p. 536), and has a sweet taste (B. 24, 538, 1839 Anm.). Benzalarabite melts at 150 (B. 27, 1535). Diacetone Arabite boils at 145-152 (23 mm.) (B. 28, 2533). 2. Xylite, C 5 H 7 (OH) 5 , is syrup-like and optically inactive. It results from the reduction of xylose (p. 536, B. 24, 538; 1839 Anm. ; R. 567; 27, 2487). 3. Adonite, C 5 H 7 (OH) 5 , melts at 102 and is optically inactive. It occurs in Adonis vernalis, and is produced by the reduction of ribose (p. 536 ; B. 26, 633). Adonit-diformacetal melts at 145 (B. 27, 1893). Adonit-diacetone boils at 150-155 (17 mm.). 4. Rhamnite, CH 3 . C 5 H 6 (OH) 5 , melting at 121 and dextrorotatory, results from the reduction of rhamnose (p. 536; B. 23, 3103). 2. TETRAOXYALDEHYDES, ALDOPENTOSES. The tetraoxyaldehydes, the first oxidation products of the pentahy- dric alcohols, are closely related to the pentaoxyaldehydes or aldohex- oses, the first class of the carbohydrates in the more restricted sense, to which also thealdopentosesare very similar in chemical deportment. Whereas formerly the carbohydrates occupied a special position in the province of aliphatic chemistry, they are now found to be very closely allied to simpler classes of bodies. All aldehyde- and ketone-alcohols, which can be regarded as the first oxidation products of the simplest representatives of the polyhydric alcohols, contain, like the carbohy- drates in a narrower sense, not only carbon, but also hydrogen and oxygen in the same proportion as water, e. g. : CHO CHO CHO CHO CHO CH 2 OH CHOH [CHOH] 2 [CHOH] 3 [CHOH] 4 Glycolyl CH 2 OH CH 2 OH CH 2 OH CH 2 OH Aldehyde Glycerose Erythrose Arabinose Glucose (Diose,C 2 H 4 O2) (Triose, C 3 H 6 O 3 ) (Tetrose, C 4 H 8 O 4 ) (Pentose, C 5 H 10 O 5 ) (Hexose, C 6 H 12 O 6 ) The simplest carbohydrates are, therefore, aldehyde-alcohols, such as those just mentioned, or ketone alcohols e. g., fructose, CH 2 OH .- CO . [CH . OH] 3 CH 2 . OH (p. 551). The aldopentoses show the following reactions in common with the aldohexoses: 1. They form ethers with alcohols in the presence of small quanti- ties of hydrochloric acid (B. 28, 1156). \a. They form mercaptals with the mercaptans in the presence of hydrochloric acid (B. 29, 547). 2. They are reduced by sodium amalgam to alcohols : pentites. TETRAOXYALDEHYDES, ALDOPENTOSES. 535 3. Nitric acid oxidizes them to oxycarboxylic acids : tetraoxymono- and trioxydicarboxytic acids. 4. They yield osamines with methyl alcoholic ammonia (B. 28, 3082). 5. Hydrazine converts the pentoses into aldazines (B. 29, 2308). 6. Phenylhydrazine changes them to hydrazones and characteristic dihydrazones : osazones. 7. They yield oximes with hydroxylamine. 8. By successive treatment with prussic acid and hydrochloric acid they pass into pentaoxyacids, the lactones of which may be reduced to hexoses (p. 564), whereby consequently the synthesis of a hexose from a corresponding pentose is realized. 9. They reduce Fehling's solution. 10. They combine with aldehydes, particularly with chloral and bromal. 11. They unite with acetone in the presence of traces of hydro- chloric acid. However, the aldopentoses are (i) not fermented by yeast; (2) they yield furfurol or alkyl furfurols when they are distilled with hydrochloric acid or with dilute sulphuric acid. This reaction can be applied in the quantitative determination of the aldopentoses (B. 25, 2912). (3) When they are heated with phloroglucin and hydro- chloric acid they acquire a cherry-red color (B. 29, 1202). Formation. Their production from natural products will be indi- cated under the individual aldopentoses. However, a reaction will be given in this connection, which promises to afford a general method for the conversion of aldohexoses into aldopentoses. On treating d-glucosoxime (p. 550) with acetic anhydride and sodium acetate, the nitrile of pentacetylgluconic acid is obtained. When this is treated with caustic alkali, and then with hydrochloric acid, it gives off first the prussic acid, and then the acetyl groups, in order to become d-arabinose (Wohl, B. 26, 740) : CH = N(OH) CN H.C.OH HCO.COCH, H . CO HO.C.H CH 3 .COOCH HO.C.H H.C.OH HCO . COCH S H.C.OH H.C.OH HCO.COCH 3 H.C.OH CH 2 OH CH 2 . O . COCH, CH 2 . OH d-Glucosoxime Nitrile of Peiitacetyl d-Arabinose. Gluconic Acid d-Arabinose is. the first aldopentose prepared synthetically, as d-glu- cose (p. 553) can be synthesized. The aldopentoses of the formula CH 3 (OH) . CH . (OH) . CH(OH) . CH . OH . - 536 ORGANIC CHEMISTRY. CHO, containing three asymmetric carbon atoms, can appear theoretically in eight optically active isomerides, and four optically active, racemic or [d -f- 1] modifica- tions which can be resolved (p. 55^)- 1. Arabinose, CH a (OH] |. (CH. OH) 3 . CHO, is known in three modifications: \-Arabinose, pectinose, melting at-i6o, is obtained from cherry gum on boiling with dilute sulphuric acid. Sodium amalgam converts it into arabite. It is dextro-rotatory, and reduces Fehling's solution. Oxidation converts it into 1-arabonic acid (p. 537), and 1-trioxyglutaric acid (melting at 127). Boiling hydro- chloric acid converts it into furfurol. Methyl-l-arabinoside, C 5 H 9 O 5 . CH 3 , melts at 169-171 (B. 26, 2407; 28, 1156). \-Arabinosazone, C 5 H 8 O 8 (N 2 HC 6 H 5 ) 2 (B. 24, 1840 Anm.), melts at 160. \-Arabinose- p-bromphenylhydrazone melts at 150-155 (B. 27, 2490). \-Arabinose-oxime melts at 132-133 (B. 26, 743). Arabinosone, see B. 24, 1840 Anm. Arabinose Ethyl Mercaptal melts at 125. Arabinose Ethylene Mercaptal melts at 154. Arabinose Methylene Mercaptal melts at 150 (B. 29, 547). Arabinochloral : a-form melts at 124, the ft- variety at 183. Arabinobromal, C 6 H 8 O 6 : CH . CBr 3 , melts at 210 (B. 29, R. 544). Arabinose Diacetone melts at 42 (B. 28, 1164). d- Arabinose is formed by the breaking-down of d-glucosoxime ; it is Isevorotatory. &-Arabinosazone melts at 160. &- Arabinose- diacetamide, C 5 H JO O 4 (NH . CO . CH 3 ) 2 , melts at 187. [d -|- 1] Arabinose is formed by the union of the two optically active arabinoses. [d-f \\-Arabinosazone melts at 166 (B. 27, 2491). 2. Xylose, Wood Sugar, C 4 H 5 (OH) 4 . CHO, is obtained by boiling wood-gum (beech- wood, jute, etc.) with dilute acids (B. 22, 1046; 23, R. 15; 24, 1657). It is dextro-rotatory. By reduction it forms xylite (p. 534) and when oxidized, xylonic acid (p. 537) and i-trioxyglutaric acid (m. p. 152). Prussic acid converts it into 1-gulonic acid (p. 566) and 1-idonic acid (p. 567). Xylosazone melts at 160. [d-fl] Xylosazone melts with decomposition at 2IO-2I5 (B. 27, 2488). Methyl Xyloside, C 5 H 9 O 5 . CH 3 . The a-form melts at 91, and the /3- variety at 156 (B. 28, 1157). Xylochloral melts at 132 (B. 28, R. 148). 3. Lyxose is formed by the reduction of the lactone of lyxonic acid (p. 537)- Prussic acid converts it into acids, which yield mucic acid on oxidation (B. 29, 584). 4. Ribose, C 4 H 6 COH) 4 . CHO, is obtained from 1-arabinose, by oxidizing the latter to 1-arabonic acid (p. 537), then rearranging the latter to ribonic acid (p. 537) by heating it with pyridine, and finally reducing the ribonic acid (B. 24, 4220). 5. Rhamnose, or Isodulcite, CH 3 (CH . OH) 4 CHO + H 2 O, melts at 93 in anhydrous form; at 122-126 when crystallized from acetone. It is dextrorotatory (B. 29, R. 117, 340). It results upon decomposing different glucosides (quercitrine, xanthorhamnine, hesperidine) with dilute sulphuric acid. Isodulcite yields a-methyl- furfurol when distilled with sulphuric acid (B. 22, R. 751). It yields rhamnite upon reduction, and by oxidation 1-trioxyglutaric acid (m. p. 127). CNH and hydrochloric acid convert it into rhamnose carboxylic acid (p. 567; B. 22, 1702). Its oxime has been decomposed into methyl tetrose (p. 521) (B. 29, 1378). Its hydrazone melts at 159 and its osazone at 180 (B. 20, 2574). Acetone Rhamnoside, C 6 H 10 O 6 : C S H 6 , melts at 90 (B. 28, 1162). Rhamnose Ethyl Mercaptal melts at 136. Ethylene Mercaptal melts at 169 (B. 29, 547)- 6. Isorhamnose has been obtained by the reduction of the lactone of isorham- nonic acid. 7. Chinovose, CH 3 [CH . OH] 4 CHO, isomeric with rhamnose, is a product obtained by decomposing chinovine, occurring in varieties of quina and cinchona with hydrochloric acid. Its osazone melts at 193-194 (B. 26, 2417). 8. Fucose, C 6 H 12 O 5 , isomeric with rhamnose, results when sea weeds (fucus varieties) are heated with dilute sulphuric acid. TETRAOXYMONOCARBOXYLIC ACIDS. 537 3. TETRAOXYMONOCARBOXYLIC ACIDS. Acids of this class are obtained by oxidizing the aldopentoses with bromine water or dilute nitric acid. They readily pass into lactones, some of which yield pentoses on reduction. Furthermore, oxidation changes them in part to dicarboxylic acids. Hydriodic acid reduces some of them to lactones of the monoxyparaffin carboxylic acids. All the known acids are optically active. Tetraoxy-n-valeric acids, as aldopentoses with an equal number of carbon atoms, have theoretically eight optically active forms, three of which are known, and four [d -\- 1] modifications. 1. 1-Arabonic Acid, CH 2 (OH) . (CH . OH) 3 . CO 2 H, is obtained from 1-arabi- nose (B. 21, 3007). When liberated from its salts by mineral acids, it splits off water and becomes the lactone C 5 H 8 O 5 , melting at 95-98. P'urther oxidation changes it to trioxyglutaric acid. Its phenylhydrazide melts at 215 (B. 23, 2627 ; 24, 4219). When it is heated to 145 with pyridine it yields along with pyromucic acid some of the isomeric 2. Ribonic Acid, which under like treatment reverts in part to arabonic acid. Its lactone, C 5 H 8 O 5> melts at 72-76 (B. 24,4217). Its phenylhydrazide melts at 162-164. Arabonic and ribonic acids are Isevorotatory. 3. Xylonic Acid, obtained from xylose by bromine, when heated with pyridine yields 4. Lyxonic Acid, the lactone of which melts at 113 (B. 29, 581). See further lyxose, p. 536. 5. Rhamnonic Acid, from rhamnose and bromine, immediately passes into its lactone, C 6 H 10 O 5 , melting at 150-151 (B. 23, 2992 ; A. 271, 73). When heated to 150 with pyridine it changes partly to 6. Isorhamnonic Acid, the lactone of which melts at 150-152, and when oxi- dized yields xylotrioxyglutaric acid (B. 29, 1961). See also isorhamnose, p. 536. 7. Saccharic Acid changes into Saccharin, its lactone : CH 2 (OH) . CH(OH) . CH(OH) . C(OH)<^Q H Saccharic Acid CH 2 (OH) . CH . CH(OH) . C(OH) . CH, Saccharin which is obtained by boiling dextrose and laevulose (or from invert sugar) with milk of lime (B. 15, 2954). Saccharin dissolves with difficulty in water (in 18 parts), forms large crystals, tastes bitter, melts at 160, and sublimes without decomposition. It is reduced to a methyl-y-valerolactone, or ay-dimethyl butyrolactone when heated with hydriodic acid (A. 218, 373). It yields a phenylhydrazide with phenylhydrazine. It melts at 165. Isomerides of saccharin : Isosaccharin, C 6 H 10 O 5 , melting at 95, when heated with HI yields ay-dimethyl- valerolactone. Metasaccharin, C 6 H 10 O 5 , melts at 142. Hydriodic acid reduces it to y-n- caprolactone (p. 346). Both isomerides are produced when milk sugar is treated with lime (B. 18, 631, 2514; 26, 1651). ORGANIC CHEMISTRY. 4. TRIOXYDICARBOXYLIC ACIDS. Tri-oxy-n-glutaric Acids, CO 2 H[CHOH] S CO 2 H, can theoreti- cally exist in four stereochemical modifications, corresponding to the four pentites (p. 533), and in addition in an inactive form, which can be decomposed. 1-Trioxyglutaric Acid, melting at 127, corresponds to arabinose, and is formed when arabinose, sorbinose, and rhamnose are oxidized with nitric acid (B. 24, 4214; 27, 383; 21, 3276). Xylotrioxyglutaric Acid, melting at 152, is produced by the oxidation of inactive xylose and corresponds to xylite (p. 534)- Ribotrioxyglutaric Acid, resulting from the oxidation of ribose, inactive, readily passes into an inactive lactonic acid, C 5 H 6 O 6 , melting at 170-171 (B. 24, 4222). It corresponds to adonite (p. 534). Saccharon, C 6 H 8 O 6 , is the lactone of Saccharonic Acid : CO 2 H . CH . CH(OH) . C(OH) . CH 3 CO 2 H . CH . CH(OH) . C(OH) . CH 3 OH CO 2 H O CO Saccharonic Acid Saccharon. Both are formed when saccharin is oxidized by nitric acid (A. 218, 363)- The acid is quite soluble in water. It forms large crystals. In the desiccator or when heated to 90 it breaks up into water and its 1-lactone, saccharon, melting at 145-156 (A. 218, 363). On boiling with HI it is reduced to a-methyl glutaric acid (P- 453)- PO TT Trioxyadipic Acid, C 4 H 5 (OH) 3 <^ O 2 H , results from the oxidation of meta- saccharin (see above) with dilute HNO 3 (B. 18, 1555). It melts at 146 with decom- position. Heated with HI it is reduced to adipic acid. 5. DIOXYKETONE DICARBOXYLIC ACIDS: The pyrone dicar- boxylic esters, resulting from the condensation of acetone dicarboxylic esters with aldehydes, are anhydrides (like ethylene oxide) of the dioxyketone dicarboxylic acids. Dimethyl-tetrahydropyrone Dicarboxylic Ester, from acetone dicarboxylic ester, acetaldehyde, and hydrochloric acid (B. 29, 994), melts at 102. 6. TRIKETONE DICARBOXYLIC ACIDS. Acetone Dioxalester, Dtethyl Xanthochelidonic Ester, CO[CH 2 . CO . CO 2 C 2 H 5 ] 2 , melting at 103-104, is obtained from acetone, oxalic ester, and sodium ethylate. Hydrochloric acid converts it into Chelidonic Ester, COO S 2 2 S 5 , melting at 63. Some other acids, related to the preceding, can also be derived from pyrone, PENTACARBOXYLIC ACIDS. 539 7. DIOXYTRICARBOXYLIC ACIDS. TRIBASIC ACIDS. Desoxalic Acid, C 2 H(OH) 2 (CO 2 H) 3 , is a deliquescent, crystalline mass. Its tri-ethyl ester, C 5 H 3 (C 2 H 5 ) 3 O 8 , results from the action of sodium amalgam upon diethyl oxalate. It melts at 78 and boils at 156 (2 mm.). When its aqueous solu- tion is evaporated, or when its ester is heated with water or dilute acids to 100, the acid yields carbon dioxide and racemic acid : HO . C<~ 2 HO . CH CO 2 H | C ' H = I + C0 2 HO.CH CO 2 H HO.CH CO 2 H Desoxalic Acid Racemic Acid. Acid radicals can be substituted for the two hydroxyl groups of the desoxalic ester Heated with hydriodic acid, desoxalic acid gives off carbon dioxide, and is reduced to succinic acid. Desoxalic ester and phenylhydrazine yield phenylhydrazine glyoxylic ester, while isonitrosomalonic ester and glycollic acid are the products with hydroxylamine (B. 29, R. 908). Oxycitric Acid,C 6 H 8 O 8 C 3 H 3 (OH) 2 . (CO 2 H) 3 ,dioxytricarballylic acid, accom- panies aconitic, tricarballylic, and citric acids in beet juice, and is produced by boil- ing chlorcitric acid (from aconitic acid and C1OH) with alkalies or water (B. 16, 1078). Dioxypropenyl Tricarboxylic Acid, C 6 H 8 O 8 = C 3 H 3 (pH) 2 (CO 2 H) 3 , results from the oxidation of isosaccharin with nitric acid. It is a thick syrup. At 100 it loses carbon dioxide, and forms dioxyglutaric acid, C 3 H 4 (OH) 2 . (CO 2 H) 2 , which is different from the dioxyglutaric acid obtained from glutaconic acid (B. 18, 2514). Hydriodic acid and phosphorus convert it into glutaric acid, C 3 H 6 (CO 2 H) 2 . 8. MONOKETtfNE TETRACARBOXYLIC ACIDS. C0 2 C 2 H 5 C0 2 H C0 2 C 2 H 5 CO 2 C 2 H 5 Aconitoxalic Ester, I I I > compare p. 518. CH == C CH CO The ammonium salt of this acid is found when ammonium oxalacetic ester is boiled with alcohol (B. 28, 790). 9. PENTACARBOXYLIC ACIDS. Propenyl Pentacarboxylic Acid, C 3 H 3 (CO 2 H 5 ), melts at 149-150. It is ob- tained from its ethyl ester, which is formed by the action of sodium malonic ester upon chlorethenyl tricarboxylic ester (p. 517). Butane Pentacarboxylic Ester, CO 2 C 2 H 5 . CH 2 . CH(CO 2 C 2 H 5 )C(CO 2 C 2 H 5 ) 2 .- CH 2 . CO 2 . C 2 H 5 , boiling at 216-218 (16 mm.), is obtained from chlorsuccinic ester and sodium ethenyl tricarboxylic ester. Higher Polycarboxylic Ethyl Esters have been obtained from sodium propane penta- carboxylic esters with chlormalonic esters and chlorpentane pentacarboxylic ester : Butane Heptacarboxylic Ester, C 4 H 3 (CO 2 C 2 H 5 ) 7 , boils at 280-285 (130 mm.). Hexane Decacarboxylic Ester, C 6 H 4 (CO 2 C 2 H 5 ) 10 , is a yellow oil. Octan-tesser-akaideca-carboxylic Ester, C 8 H 4 (CO 2 C 2 H 5 ) 14 , the highest known car- boxylic ester, is a thick oil, and results when chlorbutane heptacarboxylic ester acts upon sodium butane heptacarboxylic ester (B. 21, 2111). 54 ORGANIC CHEMISTRY. VIII. HEXA- AND POLYHYDRIC ALCOHOLS, AND THEIR OXIDATION PRODUCTS. I A. HEXAHYDRIC ALCOHOLS, HEXAOXYPARAFFINS, HEXITES. The hexahydric alcohols approach the first class of sugars (p. 572) the glucoses very closely. They resemble them in properties. They have a very sweet taste, but they do not reduce an alkaline copper solution, and are not fermented by yeast. 5-Mannitol, 5-sorbitol, and dulcitol occur in nature. These three and certain hexites have been prepared by the reduction of the corresponding glucoses aldo- and keto-hexoses with sodium amalgam. Moderate oxidation converts them into glucoses. The compounds which the hexites yield with aldehydes, especially formaldehyde and benzaldehyde, in the presence of hydrochloric acid or sulphuric acid, or with acetone and hydro- chloric acid, are characteristic of them (A. 289, 20; B. 27, 1.531; 28, 2531). The simplest hexites with six carbon atoms contain four asymmetric carbon atoms in the molecule. According to the theory of van 't Hoff and LeBel, 10 simple spacial isomeric forms are possible for such a compound. i. Mannitol or Mannite, CH 2 OH[CH . OH] 4 CH 2 OH, exists in three modifications : dextro-, laevo-, and inactive mannitol ; the latter is identical with the a-acrite made from synthetic a-acrose or [d -f- 1] fructose. It is the starting-out material for the synthesis of numerous derivatives of the mannite series (B. 23, 373), and also of grape-sugar (p. 548) and of fruit-sugar (p. 551), as will be more fully explained under these bodies. The ordinary, or d-mannitol, occurs rather fre- quently in plants and in the manna-ash {Fraxinus ornus), the dried sap of which is manna. It is obtained from the latter by extraction with alcohol and allowing the solution to crystallize. It is produced in the mucous fermentation of the different varieties of sugar, and may be artificially prepared by the action of sodium amalgam upon d-mannose and fruit-sugar, or d-fructose (B. 17, 227), Mannitol crystallizes from alcohol in delicate needles, and from water in large rhombic prisms. It possesses a very sweet taste and melts at 166. Its solution is dextro-rotatory in the presence of borax. When oxidized with care, it yields fruit-sugar (called manni- tose, B. 20, 831), and d-mannose (B. 21, 1805). Nitric acid oxi- dizes mannitol to d-mannosaccharic acid (B. 24, R. 763 ; p. 569), erythritic acid, and oxalic acid. Hydriodic acid converts it into hexyl iodide. When mannitol is heated to 200 it loses water and forms the anhydrides, Man- nitan, C 6 H 12 O 5 , and Mannide, C 6 H ]0 O 4 . The latter is also obtained by distilling mannitol in a vacuum. It melts at 87 and boils at 176 (30 mm.). HEXAHYDRIC ALCOHOLS, HEXAOXYPARAFFINS, HEXITES. 541 Esters. Mannitol dichlorhydrin, C 6 H 8 < L. ' 4 , is formed when mannitol is I '-'a heated with concentrated hydrochloric acid. It melts at 174. Hydrobromic acid yields the dibromhydrin, C 6 H 8 j ^ H \ melting at 178. Nitro-mannite, C 6 H 8 (O. NO. 2 ) 6 , melting at 108, is obtained by dissolving man- nitol in a mixture of concentrated nitric and sulphuric acids. It crystallizes from alcohol and ether in bright needles ; it melts when carefully heated and deflagrates strongly. When struck it explodes very violently. Alkalies and ammonium sul- phide regenerate mannitol. Hexacetyl-d- Mannitol, C 6 H 8 (OCOCH 3 ) 6 , melts at 119 (B. 12, 2059). Hexabenzoyl Mannitol melts at 149. Mannitol Triformal, C 6 H 8 O 6 (CH 2 ) 6 , melts at 227 (A. 289, 20). Tribenzal Mannitol, C 6 H 8 O 6 (CH . C 6 H 5 ) 3 , melts at 213-217 (B. 28, 1979). Triacetone Mannitol, C 6 H 8 O 6 (C 3 H 6 ) 3 , melting at 69, is obtained from mannitol, acetone, and a little hydrochloric acid. It has a bitter taste (B. 28, 1168). Laevo-mannitol, 1- Mannite, is obtained by the reduction of 1-mannose (from 1-arabinose carboxylic acid, p. 566) in weak alkaline solution with sodium amalgam (B. 23, 375). It is quite similar to ordinary mannite, but melts a little lower (163- 164), and in the presence of borax is laevorotatory. Inactive Mannitol, [d + 1] Mannite, is produced in a similar manner, from inactive mannose (from i-mannonic acid). It is identical with the synthetically prepared a-acrite (from a-acrose, p. 552) (B. 23, 383). It resembles ordinary man- nitol, melts 3 higher (at 168), and in aqueous solution is inactive even in the presence of borax. Nitric acid oxidizes it to inactive mannose and inactive man- nonic acid. The latter can be resolved into d- and 1-mannonic acids (B. 23, 392). d- and 1-Mannono-lactones may be reduced to d- and 1-mannoses, and these to d- and 1-mannites. All of these compounds have been synthesized in this way. 2. d- and 1-Idites are colorless syrups formed by the reduction of d- and 1-idoses. Their tribenzal compounds melt at 219-223 (B. 28, 1979). 3. d-Sorbite (p. 558), C 6 H ]4 O 6 -f- H 2 Q, occurs in mountain-ash berries, forming small crystals which dissolve readily in water. When heated they lose water and melt near no . It is produced in the reduction of d-glucose, and together with d-man- nite in the reduction of d-fructose (p. 551) (B. 23, 2623). It is reduced to secondary hexyl iodide (B. 22, 1048) when heated with hydriodic acid. Sorbite Triformal, C 6 H 8 O 6 (CH.,) 6 , melts at 206 (A. 289, 23). Triacetone Sorbite, C 6 H 8 O 6 (C 3 H 6 ) 3 , melts at 45 and boils at 172 (25 mm.). \-Sorbite (p. 558), melting at 75, is obtained by the reduction of 1-gulose (p. 551) (B. 24, 2144). 4. Dulcitol, Dulcite, C B H 14 O 6 , occurs in various plants, and is obtained from dulcitol manna (originating from Madagascar manna). It is made artificially by the action of sodium amalgam upon milk sugar and d-galactose. It crystallizes in large monoclinic prisms, having a sweet taste. It dissolves in water with more difficulty than mannite, and is almost insoluble in boiling alcohol. Its solution remains optic- ally inactive even in the presence of borax (B. 25, 2564). It melts at 188. Hydriodic acid converts it into the same hexyl iodide that mannitol yields. Nitric acid oxidizes dulcitol to mucic acid. There is also an intermediate aldehyde com- pound that combines with two molecules of phenylhydrazine and forms the osazone, C 6 H 10 4 (N T 2 H . C 6 H 5 ) 2 (B. 20, 1091). Hexacet-dulcite melts at 171. Dibenzaldulcite, C 6 H ]0 O 6 (CH. C 6 H 5 ) 2 , melts at 215-220 (B 27, 1534)- Diacetone Dulcite, C 6 H 10 O 6 (C 3 H 6 ) 2 , melts at 98 and boils at 194 (18 mm.) (B. 28, 2533). 5. &-Talite (p. 559) is a syrup. It is produced in the reduction of a-talose. Tribenzal-a-talitem&te at 200-206 (B. 27, 1527). [d -f- 1] Talite, melting at 66, is formed by the reduction of the body produced -when dulcite is oxidized with PbO 2 and hydrochloric acid (B. 27, 153)- 54 2 ORGANIC CHEMISTRY. 6. Rhamnohexite, CH 3 . [CH . OH] 5 . CH 2 OH, melting at 173, is formed when rhamnohexose (p. 551) is reduced with sodium amalgam (B. 23, 3106). i B. HEPTAHYDRIC ALCOHOLS : Perseite or Mannoheptite, C 7 H 9 - (OH) 7 , is known in three modifications : d-mannoheptite, 1-mannoheptite, and [d -f- 1J mannoheptite. The d-mannoheptite or perseite occurs in Lattrtts persea, and is obtained, like the other two modifications, by the reduction of the corresponding mannoheptoses (B. 23, 936, 2231). The [d -{- 1] mannoheptite is formed when equal quantities of d- and 1-mannoheptite are mixed (A. 272, 189). Hydriodic acid reduces it to hexahydrotoluene (B. 25, R. 503). d- and 1- Mannoheptite melt at 187, and are optically active, [d -j- 1] Manno- heptite melts at 203. rt-Glucoheptite, CH 2 OH(CHOH) 5 CH 2 OH, is obtained from a-glucoheptose. It melts at 127-128 (p. 553 ; A. 270, 81). Triaceione-a.-glucoheptite, C 7 H 10 O 7 (C 3 H 6 ) S , boils at 200 (24 mm.) (B. 28, 2534). a-Galaheptite, C 7 H 16 O 2 , melts at 183. It is obtained from a-galaheptose (p. Anhydro-enneaheptite, C 9 H 18 O 6 , melting at 156, is formed from seton and formaldehyde with lime and water. It is an anhydride of the heptahydric alcohol [CH 2 OH] 3 : C.CH(OH)C : [CH 2 OH] 3 (B 27, 1089; A. 289,46). Volemife, C 6 H 2 (OH) 7 , melting at 149-151, is found in Lactarius volemus (B. 28, 1973). i C. OCTAHYDRIC ALCOHOLS: a-Gluco-octite, CH 2 OH[CH . OH] 6 .- CH 2 . OH, is obtained from o-gluco-octose (p. 553, A. 270, 98), and melts at 141. d-Manno-octite, CH 2 OH[CHOH] 6 CH 2 OH, from manno-octose, melts at 258. It dissolves with difficulty in water. i D. NONO-HYDRIC ALCOHOLS: Glucononite, C 9 H 20 O 9 , melting at 194, is obtained from glucononose (A. 270, 107). 2 and 3. PENTA-, HEXA-, HEPTA-, AND OCTO-OXY- ALDEHYDES AND KETONES. The long-known representatives of the first class of carbohydrates, which are produced by hydrolysis from the more complex carbo- hydrates, the so-called saccharobioses (p. 573), like cane-sugar, maltose, and milk-sugar, and from the polysaccharides, I][ 45)- d-Glucose Mercaptal, C 6 H ]2 O 5 (SC 2 H 5 ) 2 , melting at 127, is obtained from d-glucose, mercaptan, and HC1. d-Glucose-ethylene Mercaptal, C 6 H 12 O 5 : S 2 C 2 - H 4 , melts at 143. d-Glucose-trimethylene Mercaptal, C 6 H 12 O 5 : S 2 C 3 H 6 , melts at 130. d-Glucosebenzyl Mercaptal, C 6 H 12 O 3 (SCH 2 . C 6 H 5 ) 2 , melts at 133 (B. 29, 547)- d-Glucose Monacetone, C 6 H ]0 O 6 : C(CH 3 ) 2 , melts at 156. d-Glucose Diacetone, C 6 H 8 O 6 [C(CH 3 ) 2 ] 2 , melts at 107 (B. 28, 2496). d-Chloralose, melting at 189, and d-Parachloralose, C 8 H 12 C1 3 O 6 , melting at 227, are two isomeric bodies, produced by the rearrangement of d-glucose with chloral (B. 27, R. 471 ; 29, R. 177). d-Acetochlorhydrose, C 6 H 7 O(OCOCH 3 ) 4 C1, results on heating d-glucose with acetyl chloride, and has been employed in the synthesis of d-glucosides. d-Glucosoxime, C 6 H 12 O 5 NOH, melting at 137, when acted upon with acetic anhydride and sodium acetate, yields pentacetyl-d-glucono-nitrile (p. 566), from which d-arabinose was isolated (p. 536). These are reactions which render possible the breaking-down of the aldoses. &-Glucose-amido-guanidine Chloride, C 6 H 12 O 5 . CN 4 H 4 . HC1, melting at 165, is obtained from d-glucose and amido-guanidine chlorhydrate (B. 27, 971). &-Glucose-aldazine, CH 2 OH[CH . OH] 4 CH : N N : CH[CH . OHJ 4 CH 2 OH, is very hygroscopic (B. 29, 2308). 1- Glucose is formed when the lactone of 1-gluconic acid is reduced. It is perfectly similar to grape sugar. It melts at 143, but is laevo-rotatory, [a] D = 51.4. Its glucosazone is, however, dextro-rotatory. Its diphenylhydrazone, C 6 H 12 - O 5 : N. N(C 6 H 5 ) 2 , dissolves with difficulty, and melts at 163 (B. 23, 2618). [d -f- l]-Glucose results from the union of d- and 1-glucose, and by the reduction of [d -j- l]-gluconic lactone. Phenylhydrazine converts it into [d -(- \\-glucosazone, C 6 H 10 O 5 (N 2 H . C 6 H 5 ) 2 . This may also be obtained from i-mannose. It crystallizes in yellow needles, melting at 217-218. The same [d -f- 1] -glucosazone is produced from synthetic a-acrose ([d -f- l]-fructose),d-mannose, d-glucose, and d-fructose (fruit- sugar) (B. 23, 383, 2620). Glucosamine, C 6 H ]3 NO 5 , is produced on warming chitine (found in lobster shells), germ cellulose of Boletus edulis, with concentrated HC1 (B. 17, 243). Nitric KETOHEXOSES. 551 acid oxidizes it to isosaccharic acid (p. 571) (B. 19, 1257; 20, 2569), and nitrous acid to chitose (B. 27, 140). It forms d-glucosazone with phenylhydrazine. Glucosamine-Oxitne llydrochloride, C 6 H n O 4 (NH 2 )(NOH)HCl, melts at 166 (B. 29, I39 2 )- (3) Gulose, CH,OH[CHOH] 4 CHO (space formula, pp. 558, 559), the second aldehyde of sorbite, is likewise known in its three modifications. They are formed by the reduction of the lactones of the three gulonic acids (p. 566), and by further reduction yield the soibites. They are syrups and are not fermented by yeast. The name gulose is intended to indicate their relationship to glucose, the first aldehyde of sorbite. 1- and [d -f- 1] Gulose Phenylhydrazone melts at 143. \~Gulosazone melts at 156. [d -\- 1] Gulosazone melts at I57-.I59 . (4) d- and 1-Idoses are prepared by the reduction of the idonic acids or their lac- tones (p. 567). They yield d- and 1-idite on reduction (p. 541) (space formula, p. 558). (5) Galactose, the aldehyde of inactive dulcite (p. 541), formed by intramolecular compensation, is known in three varieties. The [d -j- 1] galactose, melting at 140- 142, results from the reduction of the lactone of [d -j- 1] galactonic acid, and when fermented with beer yeast it becomes 1-galactose. Its phenylhydrazone melts at 158- 160 ; its osazone at 2c.6. \-Galactose, melting at 162-163 (see p. 559), yields dulcite in reduction, and mucic acid when it is oxidized. Its phenylhydrazone melts at 158-160 ; its osazone melts at 206. d- Galactose, CH. ; OH[CHOH] 4 CHO, melting at 160, is dextro rotatory and fer- mentable (B. 21, 1573) (see also p. 559; B. 27, 383). It is formed along with d-glucose in the hydrolysis of milk sugar, of galactife, C 9 H, 8 O 7 , a beautifully crystal- lized body (B. 29, 896), and of various gums (called galactans) (B. 20, 1003), which nitric acid oxidizes to mucic acid. In preparing it, boil milk sugar with dilute sulphuric acid (A. 227, 224). Dulcite is formed by its reduction, and galactonic and mucic acids by its oxidation. CNH and hydrochloric acid change it to galactose carboxylic acid (p. 568). a- and /3-Methyl-d-galactoside melt at ill and 173-175. Emulsion decomposes the second (B. 28, 1429). Galacto- chloral melts at 202 (B. 29, R. 544). Galactosamine (B. 29, R. 594). The oxime melts at 175. The osazone melts at 193. Galactose amidoguanidine chloride (B. 28, 2613). Thz penfacetyl derivative melts at 142 (B. 22, 2207). The ethyl mercafital melts at 127. The ethylene mercaptal melts at 149 (B. 29, 547). (6) d-Talose, CH 2 OH[CHOH] 4 CHO, is formed by the reduction of the lactone of d-talonic acid (p. 567) (B. 24, 3625). Space formula, p. 559; compare B. 27, 383- (71 Rhamnohexose, Methyl Hexose, CH 3 . CHOH[CHOH] 4 . CHO, melting at 181, is produced by the reduction of rhamnose carboxylic acid. The osazone melts at 200. It forms methyl heptonic acid with hydrocyanic and hydrochloric acids. 3 A. KETOHEXOSES. i. Fructose, CH 2 OH[CHOH] 3 CO . CH 2 OH, occurs as d-, 1-, and [d -f- 1] varieties. d-Fructose, Fruit Sugar, Laevulose (space formula, p. 563), melting at 95, crystallizes with difficulty, and occurs in almost all sweet fruits, together with grape sugar. It was discovered in 1847 by Dubrimfaut. It is formed, (i) together with an equal amount of grape sugar, in the decomposition of cane sugar, and is separated from the latter through the insolubility of its calcium compound (B. 28, R. 46). As fruit sugar rotates the plane of polarization more strongly toward the left than grape sugar does to the right, in the decomposition of 552 ORGANIC CHEMISTRY. the d-cane sugar a laevorotatory invert sugar solution (p. 120) results. (2) Exclusively from inuline, on heating it with water to 100 for twenty-four hours, when it is completely changed to laevulose (A. 205, 162; B. 23, 2107). It can also be obtained from secalose, a carbo- hydrate contained in green barley plants (B. 27, 3525). (3) It is formed together with d-mannose in the oxidation of d-man- nitol. (4) From d-glucosazone, which has been prepared from d-glucose or grape sugar, as well as frory d-mannose. This method of formation allies fruit sugar genetically with d-glucose and d-mannose (p. 548). Hence, in spite of its Isevorotation of [] D = 71.4 (B. 19, 393), it is called d-fructose. Fruit sugar dissolves with greater difficulty than grape sugar. By reduction it yields d-mannitol and d sorbite, and when oxidized the products are trioxybutyric acid and glycollic acid. It is partially converted into d-glucose and d-mannose by alkalies (B. 28, 3078). Heated under pressure with a little oxalic acid, d-fructose becomes /3-oxy ^-methyl furfurol (B. 28, R. 786). It yields d-fruc- tose carboxylic acid (p. 568) when treated with hydrocyanic and hy- drochloric acids ; this may be reduced to methyl butylacetic acid, and thus the constitution of fruit sugar is proved. Phenylhydrazine and fructose yield d-glucosazone, which changes by reduction to isoglucos- amine or d-fructosamine, CH 2 OH[CH . OH] 3 CO . CH 2 . NH 2 (B. 20, 2 570- Methyl-d-fructoside (B. 28, 1 1 60), lavulo- chloral, melts at 228 (B. 29, R. 544). 1- Fructose is produced by fermenting [d + 1] fructose (a-acrose) with yeast (B. 23, 389). [d -f- 1] Fructose.or o-Acrose. Sodium amalgam converts it into a-acnte, iden- tical with i-mannitol. Yeast breaks it up, leaving 1-fructose. Its osazoneis identical with i-glucosazone, from which i fructose can again be regenerated. a-Acrite can also yield i-mannonic acid, and the latter fruit sugar and grape sugar. The fructose modification, which can be resolved, is, by virtue of its synthetic formation, of the greatest importance in the synthesis of sugars (p. 553). Historical. Methylenitan was the first compound, resembling the sugars, that was prepared. Butlerow (1861) obtained it by condensing trioxymethylene (p. 194) with lime water. O. Loew (1885) obtained formose (j. pr. Ch. 33, 321) in an analogous manner from oxymethylene, and somewhat later the fermentable methose, by the use of magnesia (B. 22, 470, 478). E. Fischer considers these three com- pounds mixtures of different glucoses, among which a-acrose occurs (B. 22, 3^)- The latter (together with /3-acrose) is obtained by the action of barium hydroxide upon acrolein bromide, C 3 H 5 OBr 2 (E. Fischer and J. Tafel).and by the condensation of so-called glycerose (p. 477), a mixture of CH 2 OH . CHOH . CHO and CH 2 OH . - CO . CH 2 OH, obtained by the careful oxidation of glycerol (B 23, 389, 2131). By reduction with sodium amalgam a-acrose (identical with [d -f- 1] fructose) passes into 0-acrite, identical with [d -)- 1] mannitol. 2. Sorbinose, Sorbose, C 6 H 1? O 6 , is found in mountain-ash berries. It is incapable of fermentation under the influence of yeast. Oxidized with nitric acid it yields trioxyglutaric acid. Its osazone, sorbinosazone, melts at 164. Methyl Sor- boside melts at 120-122 (B. 28, 1160). SYNTHESIS OF GRAPE SUGAR. 553 28. ALDOHEPTOSES, 2C. ALDO-OCTOSES and 2D. ALDONONOSES (E. Fischer, A. 270, 64). Just as aldohexoses can be built up from aldopentoses, so can aldo- heptoses be obtained from aldohexoses, and aldo-octoses from the aldoheptoses, etc., e. g., hydrocyanic acid is added to d-mannose, the lactone of the d-mannoheptonic acid is then reduced to d-manno- heptose, which, subjected to the same reactions, yields d-manno- octose. The heptoses and octoses do not ferment. Heptites, octites and nonites are formed in their reduction (p. 542). d-Manno-heptose, C 7 H U O 7 , is obtained from the lactone of mannoheptonic acid (p. 5^7). Perseite yields it when oxidized (p. 542). It melts at 135. Its hydrazone dissolves with difficulty and melts about 198. Its osazone melts near 200 (B. 23, 2231). Sodium amalgam converts it into perseite (p. 542). 1-Manno- heptose (A. 272, 186). a-Gluco-heptose, C 7 H U O 7 , melts about 190. Its osazone melts about 195. ,3-Gluco-heptose (A. 270, 72, 87). a-Gala-heptose, C 7 H U O 7 , from a-galaheptonic acid, forms an osazone melting about 220. It yields gala-octonic acid (p. 567) with hydrocyanic and hydrochloric acids. /3-Gala-heptose melts with decomposition about 190-194, and is obtained from the lactone of /3-galaheptonic acid (A. 288, 139). d-Manno-octose, C 8 H 16 O 8 , is obtained from the lactone of manno-octonic acid (B. 23, 2234), and is syrup-like. u-Gluco-octose (A. 270, 95). a-Galaoctose (A. 288, 150). d-Manno-nonose, C 9 H 18 O 9 , the lactone of d-mannonononic acid, is very similar to grape sugar. It ferments under the influence of yeast. The hydrazone melts at 223, the osazone about 227 (B. 23, 2237). Glucononose (A. 270, 104). THE SYNTHESIS OF GRAPE SUGAR OR d-GLUCOSE, AND OF FRUIT SUGAR OR d-FRUCTOSE. As repeatedly mentioned, E. Fischer succeeded in isolating a- Acrose or [d -f- 1] Fructose from the condensation products of glycerose (p. 477) and formaldehyde (P- I 93)- I n his hands this became the starting-out substance for the preparation not only of fruit sugar or d-fructose, and of grape sugar or d-glucose, but also of d-mannose, of ordinary or d-mannitol, and of ordinary or d-sorbitol, as well as of the 1-modifications corresponding to the bodies just mentioned. The intimate connec- tions between these substances are represented in a diagram given on p. 554. Following the course laid down in this scheme, which finally culminated in the synthesis of fruit sugar and of grape sugar, the starting-out material is found to be a- Acrose or [d -f- 1] Fructose. This is produced by the aldol condensation of glyc- erose, a mixture of the first oxidation products of glycerol, through the agency of caustic soda. The reduction of a-acrose yields a-acrite or [d -f- 1] mannitol, which is arrived at in the following manner: When ordinary or &-mannitol is oxidized, &-mcinnose results, and the latter by similar treatment becomes ^-mannonic acid, which readily passes into its lactone. 1-Arabinose also, by rearrangement through prussic acid, becomes \-arabinose-carboxylic acid or \-mannonic acid. Its lactone combines with the lactone of d-mannonic acid and the product is the lactone of [d -j- 1] mannonic add. Upon reducing the three lactones in sulphuric acid solution with sodium amalgam, d-, 1-, and [d -f 1] mannose, and d-, 1-, and [d -f- 1] mannitol, formed by the further reduction of the latter bodies, are produced, [d -f 1] Manni- tol is identical with a-acrite or a-acrose. Therefore, [d -\- 1] mannonic acid became a very suitable starting-out substance in realizing the second synthesis, because a-acrose is very hard to obtain in anything like a desirable quantity. 47 554 ORGANIC CHEMISTRY. I h rt :2 =5 +8 T3 'o i Jl i : i *ii ii , a o c 4 M C- ^ ?2 TJ ^ '3 o -So -d ? I < t t o t t U 1 5 M M S 5 u -u J 1 1 1 1 f^l- 11 1 C 4) 4, Y 8 S ^=5 M ^^ 3 s 3 ' S ^ $ p p j^S ^ ^ O O w E E ffi ? rji O 3 D * * Cfl 1> t + t fl E E M a j r\ o Q i r i _ r > Jn 1 2j 1 O I 3 3 1 o I t K K S 4) (0 O 4) 3 M i "^ ^\ r"\ r" N r^ r^ o II J U cj c. j y ^ ts fc &-- - d ^< u + -d l__l J H ffi ffi W ffi M O ga tt t '3 t . 5 '3 .., t * .- rf K M t J U U C 13 C -4-J - ? SPACE ISOMERISM OF THE PENTITES. 555 The course from [d -f- 1] mannonic acid divides in the same way to the d-deriva- tives as it does toward the 1-compounds, because [d -f- 1] mannonic acid, like race- mic acid (p. 5 2 3)> can be resolved by strychnine and morphine into d- and 1-man- nonic acid. By the reduction, on the one hand, of the lactone of d-mannonic acid, d-mannosf and d-mannito/ are formed, and on the other hand, d-mannose and phenyl- hydrazine yield d-glucosazone, which can also be obtained from grape sugar or d-glucose, and fruit sugar or d-fructose. d-Glucosazone yields glucosone (p. 546), and the latter by reduction forms fruit sugar or d-fructose. To pass from d mannonic acid to d-glucose, heat the former to 140 with quino- line. It is then partially converted into d-gluconic acid. Conversely, the latter under the same conditions changes in part to d-mannonic acid. d-Glucose or Grape Sugar is formed in the reduction of the lactone of d-gluconic acid. d-Sorbite is pro- duced when grape sugar is reduced. Proceeding from 1-mannonic acid, the corresponding 1-derivatives are similarly obtained. \-Fructose is also formed by the fermentation of [d -j- 1] fructose or a-acrose, and 1 mannose in like manner from [d -f- 1] mannose. The gulose groups and the sugar- acids, produced in the oxidation of the pentaoxy- n caproic acids, are also considered in the table, d- Saccharic acid, resulting from the oxidation of d gluconic acid, becomes d-gulonic acid on reduction, and the lac- tone of the latter by similar treatment changes to d-gtt/ost, the second aldehyde of d-sorbite. The aldohexoses are connected with the aldopentoses (i) through \-arabinose, which, by the addition of CNH, as already mentioned, passes over into 1-arabinose carboxylic acid or 1-mannonic acid, and also into \-gluconic acid ; (2) through the xyloses, the CNH-addition product of which is the nitrile of xylose carboxylic acid, or \-gulonicacid. Oxidation changes 1-gulonic acid to 1-saccharic acid. \-Gulose and \-sorbite are formed in the reduction of its lactone. A. THE SPACE ISOMERISM OF THE PENTITES AND PENTOSES, THE HEXITES AND HEXOSES. The structural formula of the normal, simplest pentite : CH 2 OH . CH . OH . CH.- OH . CHOH . CH 2 OH, contains two asymmetric carbon atoms. The CHOH-group, standing between them is the cause of two possible inactive modifications instead of one (the case with the tartaric acids), as the result of an intramolecular compensation. Furthermore, theory permits of two optically active modifications, and a fifth optically inactive form, arising from the union of the two optically active varieties. This is the racemic or [d -f 1] modification, corresponding to [d -f 1] tartaric acid or racemic acid. These relations are most quickly and readily made clear by means of the atom models. The molecule-model is projected upon the surface of the paper, and then formulas similar to those observed with tartaric acid are derived : C0 2 H C0 2 H C0 2 H H.C.OH HO.C.II H.C.OH HOC.H IK', nil H.C.OH CO,H C0 2 H C0 2 H d-Tartaric Acid 1-Tartaric Acid i-Tartaric Acid. 556 ORGANIC CHEMISTRY. A. SPACE ISOMERISM OF THE PENTITES AND ALDOPENTOSES. The formulas for the four stereochemically different pentites arise in the same man- ner as in the case of the tartaric acids. Suppose these four pentites to be oxidized, in one instance the upper CH 2 OH group, and then the lower similar group having been converted into the CHO-group, there will result eight stereochemically different aldopentose formulas, none of which passes into any other by a rotation of 1 80. The number of predicted space-isomerides with n-asymmetric carbon atoms, and with an asymmetric formula may be more easily deduced by applying the ^formula of van 't Hoff, in which n indicates the number of asymmetric carbon atoms. In the aldo- pentoses n 3, hence 2 n = 2 3 = 8 : Pentites (and Trioxy- glutaric Adds]. Aldopentoses (and Penton-adds}. (I) CH 2 OH (I*) CHO CH 2 OH (21 ) CHO H.C.OH H.C.OH H.C.OH HO.C.H H.C.OH H.C.OH H.C.OH or HO.C.H H.C.OH H . C . OH H.C.OH HO . C . H CH 2 . OH CH 2 OH CHO CH 2 OH Adonite 1-Ribo se (Ribotrioxvglutaric (1-Ribonic Acid) Ac'id) (2) CH 2 OH (3 1 ) CHO CH 2 OH (4 1 ) CHO H . C . OH H.C.OH H.C.OH HO.CH HO.C.H HO . C . H HO;. C . H or H . C . OH H . C . OH H.C.OH H . C . OH HO.CH CH 2 OH CH 2 . OH CHO CH 2 OH Xylite 1-Xylose (Xilotrioxy- (1-Xylonic Acid) glutaric Acid) (3) CH 2 OH (5 1 ) CHO CH 2 OH (6i ) CHO | HO.C. H HO.CH HO.CH HO.C.H H . C . OH H.C.OH H . C . OH or HO'.C.H H . C . OH H . C . OH H . C . OH H.C.OH CH 2 OH CH 2 OH CHO CH 2 OH d-Arabinose 1-Lyxose (4) CH 2 OH (7 1 ) CHO CH 2 . OH (8 1 ) CHO H.C.OH H.C.OH H.C.OH H.COH HO.C.H HO . C . H HO . C . H or H . COH HO . C . H HO . C . H HO . C . H HO.CH CH 2 OH CH 2 OH CHO CH 2 OH 1-Arabite 1-Arabinose (1-Trioxvglutaric Acid) (1-Arabonic Acid) SPACE ISOMERISM OF THE HEXITES. 557 The image-isomeric aldopent'oses are capable naturally of uniting to four inactive double molecules, which can be resolved. The space-formulas (7 1 ) and (3 1 ) for or- dinary or 1-arabinose and the xyloses follow from the intimate connection of the 1-arabinoses with 1-glucose, and the xyloses with 1-gulose, as will be shown later (p. 562). If the space formula of inactive xylite may be considered as established, there re- mains but one possible formula for inactive adonite, the reduction product of ribose. Four trioxyghitaric acids (p. 538) correspond to the four theoretically predicted pentites. The same number of eight space isomerides as indicated by the pentoses are possible also for the corresponding monocarboxylic acids, the tetra~oxy-n-valeric acids, as well as for their corresponding aldehydo-carboxylic acids, and also for the ketoses of the hexite series, to which fruit sugar belongs. B. THE SPACE ISOMERISM OF THE SIMPLEST HEXITES AND THE SUGARS, THE ALDOHEXOSES AND THE GLUCONIC ACIDS.* The structural formula of the normal and simplest hexite : CH 2 OH . CH . OH . CH . OH . CH . OH . CH . OH . CH 2 OH, contains four asym- metric carbon atoms. The theory of van't Hoff and Le Bel permits of ten possible space-isomeric configurations for such a compound.* In tartaric acid we started with the point of union of the two asymmetric carbon atoms in determining the successive series ; and in hexite also we begin in the middle of the molecule, and then compare C-atom I with C-atom 4, and C-atom 2 with C-atom 3. In this manner the ten hexite configurations given on p. 558 have been derived. If we suppose each of the ten hexites to have been oxidized, in one instance the upper CH 2 OH group, and again the lower CH 2 OH group 2, to aldoses, then twenty space-isomeric aldohexoses would result. However, each of the four hexites (Xos. I, 2, 3, and 4) yields two aldoses, whose formulas by a rotation of 1 80 pass into each other, which consequently would reduce the number of possible space- isomeric aldohexoses to 16. Ten tetraoxyadipic acids (saccharic acids) correspond to the ten space-isomeric hexites; sixteen penta-oxy n-valeric acids or hexonic (gluconic acids), and sixteen aldehydo-tetraoxy-monocarboxylic acids (glucuronic acids) correspond to the. sixteen space-isomeric aldohexoses. The hexites and the tetraoxyadipic acids also have inactive, racemic or [d -f- 1] modifications, the aldohexoses, hexonic acids, and aldehydotetraoxycarboxylic acids also 8 [d + 1] modifications, as is evident from an inspection of the formulas in the appended table. The number of theoretically possible space-isomeric aldohexoses, containing four asymmetric carbon atoms in the molecule, are more readily derived by employing the van 't Hoff formula 2 n given above with the aldopentoses. This for 2* would give sixteen space isomeric aldohexoses. The space-isomerism of the ketohexoses, containing three asymmetric C-atoms, is like the isomerism of the aldopentoses. * Die Lagerung der Atome im Raum von J. H. van 't Hoff, and Grundriss der Stereochemie von Hantzsch (Breslau, 1893). 553 ORGANIC CHEMISTRY. Hexites (and Saccharic Acids]. Aldohexoses (and Hexonic Acids], (i) CH 2 OH (2) CH 2 .OH (I 1 ) CHO (2 1 ) CHO H.C.OH HO.CH H . C . OH HO . C . H H.C.OH HO. (in H . C . OH HO.C.H HC . C . H H . C . OH HO . C . H H.C.OH HO.C.H H.C.OH HO.C. H H.C.OH CH 2 OH CH 2 OH CH 2 OH CH 2 OH l-Mannite d-Mannite 1-Mannose d-Mannose (1-Mannosaccharic (d-Mannosaccharic (1-Mannonic Acid) (d-Mannonic Acid) Acid) Acid) V (3) CH 2 .OH (4) CH 2 OH (3 1 ) CHO (4 1 ) CHO HO.C.H H.C.OH HO.C.H H.C.OH H.C.OH HO.C.H H.C.OH HO . C . H HO.C.H H.C.OH HO.C.H H.C.OH H.C.OH HO.C.H H . C . OH HO.C.H CH 2 .OH CH 2 .OH CH 2 OH CH 2 OH 1-Idite d-Idite 1-Idose d-Idose (1-Idosaccharic Acid) (d-Idosaccharic Acid) (1-Idonic Acid) (d-Idonic Acid) (5) CH 2 OH (5 1 ) CHO (61) CHO HO . C . H * HO . C . H ?I . C . OH H.C.OH H.C.OH H.C.OH HO . C . H HO . C . H HO.C.H HO.d.H HO . C . H H.C.OH CH 2 OH CH 2 OH CH 2 OH 1-Sorbite 1-Glucose I-Gulose (1-Saccharic Acid) (1-Gluconic Acid) (1-Gulonic Acid) (6) CH 2 OH (7 1 ) CHO (8 1 ) CHO H.C.OH H . C . OH HO.C.H HO . C . H HO . C . H HO . C . H H.C.OH H . C . OH H . C . OH H.C.OH H.C.OH HO . C . H CH 2 OH CH 2 OH CH 2 OH d-Sorbite d-Glucose d-Gulose (d-Saccharic Acid) (d-Gluconic Acid) (d-Gulonic Acid) SPACE ISOMERISM OF THE HEXITES. 559 (7) CH 2 OH (9 1 ) CHO (lo 1 ) CHO H.C.OH H . C . OH HO.C.H HO.C.H HO.C.H H.C.OH HO . C . H HO.C.H H.C.OH H.C.OH H.;C.OH HO.C.H CH 2 OH CH 2 OH CH 2 OH Dulcite d-Galactose 1-Galactose (Mucic Acid) (d-Galactonic Acid) (1-Galactonic Acid) (8) CH 2 OH (II 1 ) CHO (I2 1 ) CHO H.C.OH H.C.OH HO.C.H H . C . OH H.C.OH HO.C.H H . C . OH H.C.OH HO . C . H H.C.OH H.C.OH HO.C.H CH 2 OH CH,OH CH 2 OH (Allomucic Acid ?) (9) CH 2 OH (I3 1 ) CHO (I4 1 ) CHO H.C.OH H.C.OH H.C.OH H . C . OH H.C.OH HO.C.H H.C.OH H.C.OH HO . C . H HO.C.H HQ. C . H HO.C.H CH 2 OH CHjOH CH 2 OH (1-Talomucic Acid) (10) CH 2 OH (IS 1 ) CHO (I6 1 ) CHO HO . C . H HO.C.H HO.C.H HO . C . H HO.C.H H.C.OH HO.C.H HO . C . H H.C.OH H.C.OH H.C.OH H.C.OH CH 2 OH CH,OH CH 2 OH d-Talite d-Talose (d-Talomucic Acid) (d-Talonic Acid) To render rational names possible, E. Fischer has proposed to indicate the con- figuration by the sign -\- or . These are not intended to show the influence of the individual asymmetric carbon atom upon the optical properties of the molecule, as van 't Hoff formerly expressed it, but merely the position of a substituent upon the right or left side of the preceding configuration formulas. The formula should be so viewed that in the sugars the aldehyde or ketone group, and in the monobasic 560 ORGANIC CHEMISTRY. acids the carboxyls stand above. The numbers begin above, and the sign -j- or represents the position of hydroxyl, e. g. : Grape Sugar, d-Glucose = Hexanpentolal -\ 1- -f (Formula 7 1 ). d-Gluconic Acid, . . . = Hexanpentol acid -\ (- -(- (Formula 7 1 ). Fruit Sugar, d-Fructose = Hexanpentol-2-on )--(-. In the case of symmetrical structure, as it exists, for example, in the diacids and alcohols of the sugar group, there is no favored position ; consequently, presuming that the numbering invariably proceeds from the top down, we get a doubled steric designation, e. g. : d-Saccharic Acid, . . = Hexantetrol diacid -| h + or 1 Dulcite , = Hexanhexol, . . -j |- or f- -j Derivation of the Space -formula for d-Glucose or Grape Sugar, the most important aldohexose. The following relations arranged first in the diagram are the basis of this derivation : d-Gulose -4- d-Gulo-lactone ^~ d-Gulonic Acid I. d-Sorbite^- -^ d-Saccharic l/^ d-Glucose -^ d-Glucono-lactone -4- d-Gluconic Acid Acid II. d-Glucose T~ d-Glucosazone -^ d-Mannose d-Mannite III. d-Fructose - -> d-Glucosazone X d-Sorbite 7[ 1-Mannonic Acid 1-Arabinose Carboxylic Acid IV. 1-Arabite -< - 1-Arabinose 34 1-Gluconic Acid >- 1-Glucose V. Xylite <- Xylose - > 1-Gulonic Acid > 1-Gulose. Xylose Carboxylic Acid Diagram I shows that d-glucose or grape sugar and d-gulose yield the same d-saccharic acid. Hence it follows that d-saccharic acid and the d-sorbite corre- sponding to it can not have the formulas (i), (2), (3), (4) (p. 558), because it is only the hexites and saccharic acids, (5), (6), (7), (8), (9), (10), which yield two space isomeric aldohexoses each. The formulas (7) and (8) of the six space-formulas rep- resent by virtue of intramolecular compensation optically inactive molecules, which therefore disappear for the optically active d-saccharic acid and d-sorbite. The fact that d-saccharic acid and d-mannosaccharic acid, d-gluconic and d-man- nonic acids, d-glucose and d-mannose, d-sorbite and d-mannite, only differ by the vary- ing arrangement of the univalent atoms or atomic groups with reference to the carbon atom, which in d-glucose and d-mannose is linked to the aldehydo-group, makes it possible to decide between the image formulas (5) and (6), (9) and (10) ; for d- and 1-saccharic acid, d-mannose and d-glucose, yield the same osazone (diagram II SPACE FORMULAS. 561 above). 1-Arabinose treated with hydrocyanic and hydrochloric acids gives rise to both 1-mannonic or 1-arabinose carboxylic acid, and 1-gluconic acid (diagram IV above). The same relations which are observed with 1-mannonic and 1-gluconic acid prevail naturally with their image isomerides d-mannonic acid and d-gluconic acid. A mix- ture of d-mannite and d-sorbite is obtained by the reduction of d-fructose. Assuming that d-sorbite and d-saccharic acid possessed the space-formulas (9) or (10) (p. 559) : (9) CH 2 OH (10) CH a OH H.C*.OH HO.C.H H.C.OH HO.C.H H.C.OH HO.C.H HO.C.H H.C*.OH CH 2 OH CH 2 OH, then d-mannite, and also d-mannosaccharic acid, would have the formulas (7) or (8) : (7) CH 2 OH (8) CH 2 OH H.C.OH HC*.OH HO.C.H HC.OH HO.C.H HC.OH H . C* . OH HC . OH CH 2 OH CH 2 OH, because only these formulas differ from (9) and (lo) exclusively in the varying arrange- ment of the atoms or atom groups with reference to asymmetric carbon atoms, desig- nated by little stars. However, formulas (7) and (8) by intramolecular compensation give rise to inactive molecules, consequently can not give back the configuration of d-mannite and d-mannosaccharic acid. Thus, for d-sorbite and 1-sorbite, d-saccharic acid and 1-saccharic acid there remain only formulas (5) and (6), from which (6) is arbitrarily selected for d-sorbite and d-saccharic acid, and (5) for 1-sorbite and 1-saccharic acid. When this has been done then all further arbitrary selection ceases ; now the formulas for all optically active compounds connected experimentally with saccharic acid are regarded as established (B. 27, 3217). Hence, the space-formula (2) falls to d-mannite and d-mannosac- charic acid, and formula (l) to 1-mannitol and 1-mannosaccharic acid, which would also give formulas (2 1 ) and (l 1 ) to d- and 1-mannonic acids. The aldohexoses (7 1 ) and (8 1 ) (p. 558) correspond to d-sorbite and the saccharic acid with space-formula (6) : (6) CH 2 OH (7 1 ) CHO (8^) CH 2 OH (8 1 ) CHO H . C . OH H.C.OH H . C . OH HO . C . H HO.C.H HO.C.H HO.C.H StatSf HO . C . H H.C.OH H.C.OH H.C.OH H.C.OH H.C.OH H.C.OH H.C.OH HO.CH CH 2 OH CH 2 OH CHO CH,OH d-Sorbite (d-Saccharic Acid). 562 ORGANIC CHEMISTRY. In order to obtain the aldehyde group at the top of the formula image, formula (8 1 ) must be turned 180. This converts it into formula (8 1 ), and the succession of the atomic groups attached to the asymmetric carbon atom is naturally not altered. The choice between formula (y 1 ) and (S l ) for d-glucose and d-gulose still remains. We are able to determine this if we can select out the space-formulas for the two image-isomerides 1-glucose and 1-gulose. This is possible with a proper considera- tion of the genetic relation of the last two bodies with 1-arabinose and xylose, as represented in diagrams IV and V (p. 560). The formulas (5 1 ) and (6 1 ) of the aldohexoses correspond to the formula (5) of 1-saccharic acid. (6 1 ) when rotated becomes (6 l ) : (5) CH 2 OH (51) CHO (6i) CH 2 OH (6') CHO HO.C.H HO.C.H HO.C.H H.C.OH H.i.OH H.i.OH H.i.OH or when H.C.OH HO.C.H HO.C.H HO.C.H r t5 HO.C.H HO.C.H HO.C.H HO.C.H H.C.OH CH 2 CHoOH CHO Cl 2 OH CH 2 OH CHO CH 2 OH 1-Sorbite (1-Saccharic Acid). Remembering that, according to diagram IV, page 560, it is possible to obtain d-glucose from 1-arabinose, and, according to diagram V, 1-gulose from xylose, then the pentoses mentioned must have the space-formulas which can be derived for formu- las (51) and (6i) by omitting the first C*-atom, becoming asymmetric in the synthesis : (6i) CHO CHO CH 2 OH H.C*.OH H.C.OH H.C.OH H.C.OH ~ HO . C . H HO . C . H HO.C.H H.C.OH H.C.OH H.C.OH CH 2 OH CH 2 OH I Xylose Xylite. CH 2 OH 1-Gulose ( 5 i) CHO HO . C* . H CHO CH 2 OH H.C.OH -4 H.C.OH ^ H.C.OH HO.C.H HO.C.H HO.C.H HO.C.H HO.C.H HO.C.H CH 2 OH CH 2 OH CH 2 OH 1-Glucose 1-Arabinose 1-Arabite. It is at once seen that the aldopentose corresponding to formula (6 1 ) must, by re- duction, yield an inactive pentite-jrj'/?V^' (p. 534), through an intramolecular compen- sation. Similarly, the pentose with formula (5 1 ) changes to an optically active pentite \-arabite (p. 534). In this manner is fixed not only the configuration for xylite and xylose, 1-arabite and 1-arabinose, but it is also demonstrated that 1-gulose, from xylose, has the formula (6 1 ), and 1 glucose, synthesized from 1-arabinose, the space- THE CONFIGURATION OF D-TARTARIC ACID. 563 formula (5 1 )- (6 1 ) is the image-formula of space-formula (6 1 ). This, therefore, belongs to &*gulose. Formula (7 1 ) corresponds to space-formula (5 *), and hence it belongs to A-gittcose. From all this it would follow that d and 1-mannoses have formulas (2 1 ) and (i 1 ), which facts confirm: that d-glucose and d-mannose on the one hand, and 1-glucose and 1-mannose on the other, pass into the same glucosazone t. I M t OH HO.C.H I H.C.OH CO.H .C.H HO.C.H '- HO .. | CH.OH I HO.C.H . .. , ? noH ^ I CH s J.TT CO 2 H _ - -- ^ L,tt s 1-Trioxy- Rhamnose a-Rhamnose- Mucic Acid Racemic Acid. glutaric Carboxylic Acid Acid This assumption has been proved through the behavior of the stereo-isomeric /2-rhamnohexonic acid, which results on heating a-rhamnohexonic acid to 140 with pyridine. All experiences go to show that the two stereo-isomeric rhamnohexonic acids only differ in the arrangement or position of the carboxyl group in direct union with the asymmetric carbon atom. Had the methyl group not been split off in the oxidation, but merely changed to carboxyl, then a- and ,3-rhamnohexonic acids would have yielded the same mucic acid because the asymmetric C-atom linked to carboxyl in a- and ,3-rhamnohexonic acid, that caused the difference in the two acids, would have been oxidized to carboxyl. /3- Rhamnohexonic acid, however, 564 ORGANIC CHEMISTRY. oxidizes to 1-talomucic acid, which justifies the preceding assumption, and conse- quently proves the rhamnose configuration, even to the position of the asymmetric carbon atom linked to methyl. Wohl's procedure permits of the conversion of rhamnose into methyl tetrose, which is oxidized to d-tartaric acid by nitric acid. Hence, we may suppose that here the methyl group is split off as in the case of the oxidation of rhamnose to 1-trioxy- glutaric acid, and of a-rhamnohexonic acid to mucic acid. This then demonstrates the configuration of d-tartaric acid (B. 29, 1377): CO 2 H H.C.OH C0 2 H HO . C . H H.C.OH ' H.t.OH HO . C . H H . C . OH v^iig COgH COgH Rhamnose Methyl Tetrose d-Tartaric Acid d-Saccharic Acid. 4. POLYOXYMONOCARBOXYLIC ACIDS. A. PENTAOXYCARBOXYLIC ACIDS. These acids are produced (i) by the further oxidation (by means of chlorine or bromine water) of the alcohols and aldoses correspond- ing to them; (2) by the reduction of the corresponding aldehydo- acids and lactones of dicarboxylic acids; synthetically, from the aldopentoses (arabinose, rhamnose, p. 536) by the aid of CNH, etc. This is analogous to the synthesis of glycollic acid from formaldehyde, and ethidene lactic acid from acetaldehyde : CNH HCl V CNH CH 2 .OH[CH.OH] 3 CHO 1-Arabinose 2H 2 HCl 2H 2 1-Glucononitrile 1-Gluconic Acid 1-Arabinose Carboxylic Acid. Deportment. Being f- and 5-oxy-derivatives, nearly all of these acids ery unstable when in a free condition. They lose water readily 342) : O 7 - > C 6 H 10 O 6 . When acted upon in acid solution by sodium amalgam, these lactones (not the acids) reabsorb two atoms of hydrogen, and are converted into the corresponding aldohexoses (E. Fischer) : r TT r\ s*. r TT r\ ^6"io u 6 ~~ ^" '~if*ifMr d-Glucono-lactone d-Glucose. PENTAOXYCARBOXYLIC ACIDS. 565 These acids, when acted upon with phenylhydrazine, form characteristic crystal- line phenylhydrazides, C 6 H n O 6 . N 2 H 2 . C 6 H 5 (B. 22, 2728). They are resolved into their components when boiled with alkalies. They are distinguished from the hydrazones of the aldehydes and ketones by the reddish-violet coloration produced upon mixing them with concentrated sulphuric acid and a drop of ferric chloride. Heated to 130-150 with quinoline or pyridine a geometric re- arrangement ensues, which is, however, restricted to the asymmetric carbon atom in union with the carboxyl. It is a reversible reaction, and therefore yields a mixture of both stereo-isomerides, e. g. (B. 27, 3*93): d- and 1-Gluconic Acid 1-Gulonic Acid d-Galactonic Acid d- and 1-Mannonic Acid. 1-Idonic Acid. d-Talonic Acid. These acids are reduced to lactones of the ^-monoxycarboxylic acids (p. 345), if they are heated with hydriodic acid and phosphorus. Isomerism. Spacial isomerides of pentaoxy-n-caproic acid are as numerous, according to theory, as the aldohexoses (p. 558), /'. e., six- teen optically active and eight [d -f- 1] modifications, which are inac- tive. Mannonic Acid, C 5 H 6 (OH) 5 . CO 2 H. The syrup-like acids d-, 1-, and [d -f- l]-mannonic acid yield d-, 1-, and [d -j- \~\-manno- saccharic acid on oxidation (p. 569). They change to lactones on evaporating their solutions, which by further reduction yield d- mannitf, \-mannife, and [d -f- Y]-manntte. [d -f- \\-Mannite is identical with a. acrite, the reduction product of synthetic a-acrose or [d -f- 1]- fructose. As [d -f- l]-mannite or a-acrite, when oxidized, yields [d -j- 1]- mannose, and the latter by similar treatment becomes [d -f- l]-man- nonic acid, which can be split into d-mannonic acid and 1-mannonic acid, we realize through these reactions the complete synthesis of all bodies of the mannite series (p. 554) : d-Mannite -^ d-Mannose -^ ---- d-Mannonp-lactpne d-Mannonic Acid --- ^- Mannosaccharic Acid a-Acrose J- a-Acrite *$ [d + 1] Mannose -^ [d+1] Mannonic Acid J>-[d-fl] Mannosac- td+IJ Fructose [d+1] Mannite charic Acid 1-Mannonic Acid - ^- 1-Mannosaccha- ric Acid 1-Mannite -^ 1-Mannose <- - 1-Mannono-lactone. d-Mannono-lactone, CeHjoOe, m.p. 149-153 MD =+ 53-8 1-Mannono-lactone, 140-150 [a] =+ 54.8 [d+lj Mannono-lactone, (CeHioOeJo, " 149-155. d- and \-Mannonophenylhydrazide, C 6 H U O 6 (N 2 H 2 . C 6 H 5 ), melts at 214-216. [d _|_ 1] Mannonophenylhydrazidc melts about 230 when it is rapidly heated. The hydrazides are converted into the acids on boiling with baryta water (B. 22, 3221). This reaction is well adapted for the purification of the acids. A very important feature is that a partial conversion of d- and l- mannonic acid into d- and I- gluconic acids occurs on heating the former to 140 with quinoline. The last two acids, subjected to the same treat- ment, change in part to d- and 1-mannonic acids. 566 ORGANIC CHEMISTRY. This method of preparing d- and l-gluconic acids shows the genetic connection existing between d- and l-glucose and the mannite series, and thereby renders possible the synthesis of grape sugar. The formation of 1-mannonic acid or 1-arabinose-carboxylic acid (together with l-gluconic acid) from 1-arabinose by means of hydro- cyanic acid constitutes one of the transitions which allows of the synthesis of aldohexoses from aldopentoses: fl- Mannonic Acid ^1-Mannono-lactone M-Mannose 1-Arabinose \ 1-Arabinose Carboxylic Acid ( 1-Gluconic Acid - M-Glucono-lactone M-Glucose. Gluconic Acid, CH 2 OH(CHOH) 4 CO 2 H, is known in the d-, 1-, and [d -f- l]-modifications (B. 23, 801, 2624; 24, 1840). 1. The lactones of these three acids change to d-, 1-, and [d -f- 1]- glucose on reduction. 2. By oxidation they become d-, 1-, and [d -f- 1] saccharic acids. 3. When heated to 140 with quinoline they change in part to d-, 1-, and [d -}- 1] mannonic acids (p. 566). Conversely, d-, 1-, and [d -f- 1] gluconic acids are won by the same treatment from d-, 1-, and [d 4- 1] mannonic acids. " The d- and 1-phenylhydrazides, C 6 H n O 6 (N 2 H 2 . C 6 H 5 ), melt about 200 when they are rapidly heated, while the [d -f- 1] phenylhydrazide melts at 190. d-Gluconic Acid, Dextronic Acid, Maltonic Acid, is formed by the oxidation of dextrose, cane sugar, dextrine, starch, and maltose with chlorine or bromine water, and is most readily obtained from glucose (B. 17, 1298) as well as from d-mannonic acid. Gluconic acid forms a syrup which, when evaporated or upon standing, changes in part to its crystalline lactone, C 6 H 10 O 6 , melting at 130-135. Sodium amalgam reduces it to ^-glucose or grape sugar (B. 23, 804). Its barium salt crystallizes with three molecules of water, the calcium salt with one. The acid is dextro-rotatory, but does not reduce Fehling's solution. Pentacetylglucononitrile, C 6 H 6 (O. C 2 H 3 O) 5 CN (B. 26, 730). Dimethylene Glu- conic Acid, C 6 H 8 O 7 ( : CH 2 ) 2 , from d-gluconic acid and formaldehyde, melts at 220 (A. 292, 31). 1-Gluconic acid is formed (i) from 1-mannonic acid (p. 566), and (2) together with 1-mannonic acid from 1-arabinose by aid of CNH. [d -f 1] Gluconic Acid is formed upon evaporating the aqueous solution of a mixture of d- and l-gluconic acids. Its calcium salt dissolves with difficulty. It is obtained like calcium racemate by mixing solutions of d- and 1-gluconates of calcium. Gulonic Acid, CH 2 OH[CHOH] 4 C0 2 H, is known in three forms, which become d-, 1-, and [d -f- 1] saccharic acids (p. 569) when they are oxidized. The reduc- tion of their lactones produces d-, 1-, and [d -\- 1] guloscs (p. 551). d- Gulonic acid is obtained by reduction of both glucuronic acid (p. 568) and d-saccharic acid. The lactone melts at 180-181 ; \he phenylhydrazide at 147-148 (B. 24, 526). \-Gulonic acid, xylose carboxylic acid, results when xylose is acted upon with CNH. This reaction unites also the aldopentoses with the aldohexoses. 1-Idonic acid is produced simultaneously, and when heated with pyridine changes partially to 1-gulonic acid. \-Gulono-lactone melts at 185. The phenylhydrazide melts at 147-149 (B. 23, ALDOSE CARBOXYLIC ACIDS. 567 2628 ; 24, 528). [d -f- 1] Gulonic Acid readily changes into its lactone, which by crystallization splits into d- and 1-gulono-lactone. Calcium [d + 1] gulonate dissolves with more difficulty than calcium d- and 1 -gulonate. The phenylhydrazide melts at I53- I 55.(B. 25, 1025). 1-Idonic Acid is formed together with 1-gulonic acid from xylose, and is separated by means of its brucine salt from the mother liquor of 1-gulono-lactone. Heated with pyridine to 140, it changes in part to 1-gulonic acid, and vice vend,. 1-Idose is its reduction product (p. 551). &-Idonic Acid, obtained from d-gulonic acid by means of pyridine, yields d-idose en reduction (B. 28, 1975). Galactonic Acid, CH 2 OH[CHOH] 4 CO 2 H, is known in three modifications. [d -j- 1] Galaclonic Acid results in the reduction of ethyl mucic ester and also of the lactone of mucic acid. Its [d -|- 1] lactone melts at 122-125. Its phenylhydrazide melts at 205. This acid can be resolved by means of its strychnine salt into the 1-salt, which is more easily soluble in alcohol, and the d-salt, which dissolves with more difficulty (B. 25, 1256). \-Galactonic Acid resembles in a remarkable degree the well-known d-Galactonic Acid, Lac tonic Acid, CH 2 OH[CHOH] 4 CO 2 H, which is produced from milk sugar, d-galactose, and gum arabic by the action of bromine water. It can be converted into d-talonic acid, and then be prepared from the latter. It crystallizes, and prolonged heating to 100 converts it into the corresponding lactone, C 6 H ]0 O 6 , melting at 90-92, which combines with water to C 6 H 10 O 6 -f- H 2 O, melting at 64- 65 (A. 271, 83). Calcium Salt, (C 6 H n O 7 ) 2 Ca + 5H 2 O. Its phenylhydrazide melts at 200-205. Sodium amalgam causes the lactone to revert to d-galactose. It yields mucic acid on oxidation with nitric acid. The amide melts at 172. The anilide melts at 210 (B. 28, R. 606). d-Talonic Acid, CH 2 CH[CHOH] 4 CO 2 H, results together with oxymethylene pyromucic acid on heating d-galactonic acid with pyridine or quinoline to 140-150. Conversely, d-galactonic acid is obtained from d-talonic acid by the same treatment (B. 27, 1526). Reduction changes it to d-talose (p. 551). Chitonic Acid is produced when HCl-glucosamine (p. 550) is changed to chitose by means of silver nitrite, and this non-isolated intermediate product is afterwards oxidized with bromine water (B. 27, 140). a-Rhamnose-carboxylic Acid, CH 3 (CH.OH) 4 . CH< R , is made from rhamnose by action of CNH, etc. The lactone, C 7 H 12 O 6 , melts at 162-168 (B. 21, 2173). ^ phenylhydrazide, C 7 H, 3 O 6 . N 2 H 2 . C 6 H 5 , melts about 210 (B. 22, 2733). When the acid is heated with hydriodic acid and phosphorus, it is reduced to normal heptylic acid. Sodium amalgam converts the lactone into methylhexose (B. 2 3. 93 6 )- Mucic acid is its oxidation product (B. 27, 384). Heated to 150-155 with pyridine, it is partly changed to 3 rhamnose-carboxylic acid. The lactone of the latter melts at 134-138, and the phenylhydrazide^ 170. When oxidized the /3-acid is converted into 1-talo-mucic acid (p. 571). B. ALDOHEXOSE CARBOXYLIC ACIDS, HEXAOXYMONOCARBOXYLIC ACIDS. Acids of this kind have been obtained from d-glucose, d-mannose, d galactose, and d-fructose by the addition of hydrocyanic acid, and the subsequent saponification of the nitrile with hydrochloric acid. (i) Mannoheptonic Acid is known in three modifications: d-Mannose-carboxylic Acid, d- Mannoheptonic Acid, CH 2 OH . [CHOH] 5 .- CO 2 H, is obtained from d-mannose (A. 272, 197). Its phenylhydrazide (see above) melts about 220 with decomposition. Its lactone melts at 148-150. Sodium amalgam reduces the lactone to d-mannoheptose, C 7 H U O 7 , and then to the hepta- hydric alcohol perseite, C 7 H 1( ,O 7 (B. 23, 936, 2226). Hydriodic acid reduces the acid to heptolactone and heptylic acid (see above and B. 22, 370). When oxidized 568 ORGANIC CHEMISTRY. it yields 1-pentoxypimelic acid (A. 272, 194). \-Mannose Carboxylic Acid is obtained from 1-mannose. \\sphenylhydrazide melts about 220 ; its lactone at 153- 154. [d -j- 1] Mannosecarboxylicacid is formed from d- and 1-mannose carboxylic acid, as well as from [d -f- 1] mannose (A. 272, 184). (2) formed together with the a-acid from glucose. The phenylhydra- zide melts at 150-152. Its lactone melts at 151-152, and yields /3, d-glucoheptose on reduction. a, d-Galactose-carboxylic Acid, a-Galaheptonic Acid, CH 2 OH[CHOH] 5 CO 2 H, is produced together with ft-galaheptonic acid from galactose. The acid melts at 145, and passes into its lactone, melting at 150. Sodium amalgam changes it into a-gala-heptose (p. 553). When oxidized it yields carboxy-d-galactonic acid (p. 571) (A. 288, 39). d-Fructose-carboxylic Acid, CH 2 OH . [CHOH] 3 C(OH) (CO 2 H)CH 2 OH, is ob- tained from fructose or laevulose by the action of hydrocyanic acid. It yields tetra- hydroxybutane tricarboxylic acid when it is oxidized. Its lactone melts at 130, and when reduced with sodium amalgam two aldoheptoses with branched C-chains result (B. 23, 937). Reduction with hydriodic acid forms heptolactone and heptylic acid, C 7 H, 4 O 2 . The latter is identical with methyl-normal butyl acetic acid (p. 249). Hence it is evident that Icevulose is a ketone-alcohol (Kiliani, B. 19, 1914; 23,451 ; 24, 348). C. ALDOHEPTOSE CARBOXYLIC ACIDS, HEPTAOXYCARBOXYLIC ACIDS. d-Manno-octonic Acid, CH 2 OH . [CHOH] 6 CO 2 H, has been obtained from d-mannoheptose. Its hydrazide melts at 243. The lactone has a neutral reaction, a sweet taste, and melts about 168. By reduction it forms d-mannoctose (p. 553)' a- and fi-Gluco-octono-lactone melt at 145 and 186 (A. 270, 93). a-Gala-octono- lactone, from a-galaheptose (A. 288, 149), melts at 220-223. D. ALDO-OCTOSE CARBOXYLIC ACIDS, OCTO-OXYCARBOXYLIC ACIDS. d-Manno-nononic Acid, CH 2 OH[CHOH] 7 CO 2 H, has been obtained from d-manno-octose. Its hydrazide melts about 254. Its lactone melts at 176. When reduced it forms d-manno-nonose. 5. TETRAOXY- AND PENTAOXYALDEHYDE ACIDS. d-Glucuronic Acid, CHO. (CH. OH) 4 . CO 2 H, is obtained by decomposing euxanthic acid (see this) on boiling with dilute sulphuric acid. Various glucoside-like compounds of glucuronic acid with camphor, borneol, chloral, phenol, and different other bodies (B. 19, 2919, R. 762) occur in urine after the introduction of these com- pounds into the animal organism. In this change the substances mentioned combine with the aldehyde group of grape sugar, the primary alcohol group of which is then oxid- ized. Boiling acids decompose them into their components. Glucuronic acid is a syrup, which rapidly passes into the lactone C 6 H 8 O 6 on warming. The latter consists of large plates, of sweet taste, melting at 175-178 C. Bromine water oxidizes it to saccharic acid. It also appears that when saccharic acid is reduced glucuronic acid TETRAOXYDICARBOXYLIC ACIDS. 569 results (B. 23, 937), and by reduction d-gluconic acid is formed (B. 24, 525). The position of the aldehyde group in camphor-glucuronic acid and euxanthic acid is fully established. Urochloralic Acid, C 8 H H C1 3 O 7 , melting at 142, decomposes with water absorption on boiling with dilute hydrochloric or sulphuric acid into glucuronic acid and trichlorethyl alcohol (p. 125). Urobutylchloralic Acid, C 10 H 15 C1 3 O 7 , decom- poses, like the preceding body, into glucuronic acid and ac/3-trichlorbutyl alcohol (p. 126). Aldehydo-galactonic Acid, COH . [CHOH] 5 CO 2 H, is obtained from d-galactose carboxylic acid, and may be converted into carboxy-galactonic acid (p. 571). 6. POLYOXYDICARBOXYLIC ACIDS. A. TETRAOXYDICARBOXYLIC ACIDS. These are obtained by the oxidation of various carbohydrates with nitric acid, and are readily prepared from the corresponding- mono- carboxylic acids upon oxidation with nitric acid. Mannosaccharic acid, the saccharic acids, and themucic acids are the most important representatives of the series. Gluconic acid yields saccharic acid, galactonic acid mucic acid, and mannonic acid mannosaccharic acid. Their lactones, by very careful reduction, can be converted into alde- hyde ox\ carboxylic acids and oxymonocarboxylic acids. When reduced by HI and phosphorus the preceding acids are converted into normal adipic acid, C 4 H 8 (CO 2 H) 2 ; hence all of them must be considered as normal space-isomeric tetraoxyadipic acids. Theoretically, ten simple and four double modifications are possible. All the tetraoxyadipic acids, when heated with hydrochloric or hydrobromic acid, change more or less readily to dehydromucic acid (B. 24, 2140). (1) Mannosaccharic Acid, CO 2 H[CHOH] 4 CO 2 H, is known in three modifications (space-formula, p. 558), which pass into double lactones when they are liberated from their salts. They also result upon oxidizing the three mannonic acids with nitric acid (p. 565). [d -f- 1] Mannosaccharo-lactone, C 6 H 6 O 6 , melts with decomposition at 190. It is formed by the union of d- and 1-mannosaccharo-lactone, and also from [d -|- 1] manno-lactone. Its diamide melts at 183-185. Its dihydrazide melts at 220-225 (B. 24, 545). &-Mannosaccharo-lactone, C 6 H 6 O 6 -f 2H 2 O, melts with decomposition, when anhydrous, at 180-192. It is produced when d-mannite, d-mannose, and d man- nonic acid are oxidized with nitric acid. Its diamide melts at 189. Its dihydrazide melts at 212 (B. 24, 544). Metasaccharic Acid, C 6 H 6 O 6 + 2H 2 O, melts at 68 ; when anhydrous, at 180. It is produced when 1-mannonic acid and the lactone of 1-ara- binose carboxylic acid are oxidized (B. 20,341, 2713). Its diamide melts at 189- 190. Its dihydrazide melts at 212-213. Diactyl-l-mannosaccharo lactone melts at 155 (B. 21, 1422; 22, 525 ; 24, 541). (2) d- and 1-Idosaccharic Acids are syrups. They are obtained by oxidizing the corresponding idonic acid (p. 567). '(3) Saccharic Acid, CO 2 H[CHOH] 4 CO 2 H, exists in three modifi- cations (space-formulas, p. 558); of these the d-saccharic acid is ordinary saccharic acid. 48 570 ORGANIC CHEMISTRY.. [d -f- \\-Saccharic Acidis formed by the oxidation of [d -(- l]-gluconic acid. Its monopotassium salt is formed on mixing solutions of equal quantities of the d- and 1-salt. Its dihydrazide melts at 210 (B. 23, 2622). Ordinary, or d-saccharic acid, results in the oxidation of cane sugar (B. 21, R. 472), d-glucose (grape sugar), d-gluconic acid, and many carbohydrates with nitric acid ; also from the action of bromine water upon glucuronic acid. It forms a deliquescent mass, readily soluble in alcohol. If the pure, syrupy acid be allowed to stand for some time, it changes to its crys- talline lactonic acid, C 6 H 8 O 7 , which melts at 130-132. It changes to glucuronic acid when reduced with sodium amalgam. Hydriodic acid reduces it to adipic acid. When oxidized with nitric acid, dextro-tartaric acid (B. 27, 396) and oxalic acid are formed. "\it primary potassium salt, C 6 H 9 KO 8 , and the ammonium salt, C 6 H 9 (NH 4 )O 8 , dissolve with difficulty in cold water. The diethyl ester is crystalline. The amide is a white powder. The tetra-acetate melts at 61. Acetyl chloride, acting upon free saccharic acid, converts it into the lactone of diacetyl-saccharic acid, C 6 H 4 (O . C 2 - H 3 O) ? O 4 , melting at 188. Monomethylene Saccharic Acid (A. 292, 40). Its diamide is a white powder. Its dihydrazide melts at 210 with decomposition (B. 21, R. 186). \-Saccharic acid is obtained upon oxidizing 1-gluconic acid with nitric acid. It is quite similar to d-saccharic acid, but is laevorotatory. It also forms a dihydrazide, melting at 214. (4) Mucic Acid, CO,H[CHOH] 4 CO,H, Acidum muctcum, corre- sponds in constitution to dulcitol. It has the space-formula No. 7 (p. 559). This is also evident from its yielding racemic acid on oxidation, and from the fact that it is formed when a-rhamnose car- boxylic acid is oxidized (p. 567 ; B. 27, 396). It is also obtained in the oxidation of dulcitol, milk-sugar (Prepara- tion, A. 227, 224), d- and 1-galactose, d- and 1-galactonic acid, and nearly all the gum varieties. It is a white crystalline powder, almost insoluble in cold water and alcohol. It melts at 210 with decomposition. When boiled for some time with water it passes into a readily soluble lactonic acid, C 6 H 8 O 7 , formerly designated paramucic acid, d-saccharo- lactonic acid (p. 569; B. 24, 2141). Reduction changes this muci-lactonic acid into [d -j- l]-galactonic acid (p. 567; B. 25, 1247). Mucic acid heated to 140 with pyridine becomes allomucic acid, from which it can be reformed under similar conditions. The ready conversion of mucic acid into furfurane derivatives is rather remarkable. Digestion with fuming hydrochloric or hydro- bromic acid changes it to furfurane dicarboxylic acid (dehydromucic acid) : C0 2 H CH(OH) . CH(OH) . CO 2 H CH = C' | =1 >0 + 3 H 2 0. CH(OH) . CH(OH) . C0 2 H CH = C s \ CO.,H PENTAOXYD1CARBOXYLIC ACIDS. 571 When mucic acid is heated alone it splits off carbon dioxide and becomes furfurane monocarboxylic acid (pyromucic acid) : C 4 H 4 (OH) 4 (C0 2 H) 2 = C 4 H 3 . CO 2 H + 3 H 2 O + CO 2 . Heated with barium sulphide it passes in like manner into a-thio- phene carboxylic acid (B. 18, 457). Pyrrol, NH 3 , CO 2 , and water are produced when the diammonium salt is heated : C 6 H 8 (NH 4 ) 2 O 8 = C 4 H 4 NH -f NH 3 -f 2CO 2 -f 4H 2 O. The neutral potassium salt and ammonium salt ', C 6 H 8 (NH 4 ) 2 O 8 , crystallize well and dissolve with difficulty in cold water ; the primary salts dissolve readily. The silver salt, C 6 H 8 Ag 2 O 8 , is an insoluble precipitate. The diethyl ester vut\\& at 158. The tetra-acetate melts at 177 (B. 21, R. 186). See p. 467 for the action of PCI. upon mucic acid. (5) Allomucic Acid, C 6 H 10 O 8 , melts at 166-171, is optically inactive, and more soluble than mucic acid, from which it is obtained on heating with pyridine, and into which it also passes (see mucic acid) (B. 24, 2136). (6) Talomucic Acid, CO 2 H[CHOH] 4 CO 2 H, is known in two space -isomeric modifications : d- Talomucic Acid, melting with decomposition at 158, and resulting from the oxidation of d-talonic acid (B. 24, 3625). 1- Talomucic Add, prepared by oxidizing /3-rhamnose carboxylic acid (p. 567) (B. 27, 384). (7) Isosaccharic Acid, CO 2 H . CH . CH(OH)OCH(OH) . CH . CO 2 H, results from HCl-glucosamine (p. 550) upon oxidizing it with nitric acid (B. 19, 1258). It melts at 185. Its solution is dextrorotatory ; (o) D = -f 46. i. The acid itself and some of its derivatives must be regarded as compounds of tetrahydro- furfurane. This is evident from the constitution formula of the acid. Other derivatives should be referred to isosaccharic acid -f- H 2 O that is, to tetraoxyadipic acid, and they are described as derivatives of noriso-saccharic acid; for example, the diethyl ester, C 6 H 8 O 8 (C 2 Hg) 2 , melting at 73, which changes in the desiccator to the diethyl ester of isosaccharic acid, C 6 H 6 O 7 (C 2 H 5 ) 2 , melting at IOI. The diacetyl isosaccharic ester melts at 49 (B. 27, 118). B. PENTAOXYDICARBOXYLIC ACIDS. Pentaoxypimelic Acid, Heptanpentol diacid, CO 2 H . [CH . OH] 5 CO 2 H, is produced in the oxidation of glucose carboxylic acid with nitric acid. The lactone is crystalline, and melts at 143 (B. 19, 1917). a-Carboxy-galactonic Acid, a- Galaheptanpentol Diacid, CO 2 H[CHOH]5CO 2 H, is formed in the oxidation of galactose-carl>oxylic acid with nitric acid. It dissolves with difficulty in water, crystallizes in plates, and melts at 171 with decomposition. /3-Galaheptanpentol Diacid, from /3-galaheptonic acid and nitric acid, is a syrup (A. 288, 155). Oxyketone Tetracarboxylic Acids : Ethyl Oxalo - citro - lactone Ester, C0 2 R C0 2 R C0 2 R CH C CH 2 , boiling at 210 (30 mm.), is obtained from oxalacetic ester CO. COO through the aldol condensation and lactone formation (A. 295, 347)- 57 2 ORGANIC CHEMISTRY. Diketo-tetracarboxylic Acids : Ethyl Dioxalosuccinic Ester, CO 2 R . CO . CH . CO 2 R r*r\ -n r^r\ ^TT r*r\ -r. ' resu ^ ts n condensing succinic ester and oxalic ester with CO 2 R . CO . LH . CO 2 R sodium ethylate. When distilled under greatly reduced pressure it loses carbon monoxide, and becomes ethane tetracarboxylic ester. When it is separated by means of sulphuric acid from its disodium compound it changes to Ethyl R COR C = C Dioxalo-succmo-lactone Ester, \Q , melting at 89 (A. 285, 1 1). CARBOHYDRATES.* This term is applied to a large class of compounds, including the natural sugars, widely distributed in nature. They contain six, or a multiple of six carbon atoms. The ratio of their hydrogen and oxy- gen atoms is the same as that of these elements in water. Most of the carbohydrates have their origin in plants, although some are produced in the animal organism. Those which occur in the vegetable kingdom meet with the most extensive application. Carbohydrates serve for the preparation of alcoholic drinks (p. 122). Starch is the chief ingredient of flour from which bread, the most im- portant nutrient, is made. It is found stored up in potatoes and grain fruits. Cellulose, related to it, is the principal constituent of wood, and is applied in paper-making and for the production of explosives. The carbohydrates in conjunction with the albuminoids constitute the most important compounds for man. Their molecular magnitude is the basis of their arrangement into these classes : Monoses, or Monosaccharides, Saccharobioses, or Disaccharides, Saccharotrioses, or Trisaccharides, Polysaccharides. The monosaccharides, including grape sugar and fruit sugar, have already been discussed in connection with the hexahydric alcohols, of which they are the first oxidation products (p. 54 2 )- Nearly all of the naturally occurring carbohydrates are optically active; their solutions rotate the plane of polarization. The specific rotatory power is not only influenced by the temperature and con- centration of their solutions, but very frequently also by the pre- sence of inactive substances (B. 21, 2588, 2599). Some represen- * " Kohlenhydrate," von B. Tollens. "Die Chemie der Zuckerarten," von E. O. von Lippmann, II. Auflage, 1895. " Die Chemie der Kohlenhydrate und ihre Bedeutung fur die Physiologic," von E. Fischer, 1894. DISACCHARTDES. 573 tatives also manifest the phenomena of birotation and semirotation (p. 549)- Constant rotation is generally attained by heating the solu- tions for a brief period. The determination of the gyratory power of the carbohydrates by means of the saccharimeter serves to ascer- tain their purity, or for the determination of their amount when dis- solved : optical sugar test, saccharimetry (p. 574). A. DISACCHARIDES, SACCHAROBIOSES. Disaccharides, consisting of two molecules of glucoses or monoses (p. 549), hence termed biases, have up to the present only been known with the hexoses, C 6 H 12 O 6 . Their formula would therefore be C 12 H M O U . By the absorption of water they are resolved into two molecules of the hexoses : This reaction is known as hydrolytic decomposition or hydrolysis. The higher carbohydrates are also capable of undergoin^this change. The constitution of the disaccharides indicates that they are ether- like anhydrides of the hexoses. The union is effected through the alcohol or aldehyde groups. Milk sugar and maltose also contain the aldose group, CH(OH) . CHO, because they reduce Fehling's solution upon boiling, form osazoneswith phenylhydrazine, and when oxidized with bromine water yield monobasic acids, C^E^O^, lacto-and malto- bionic acid (p. 576) (B. 21, 2633; 22, 361). Cane sugar does not show reducing power and does not yield an osazone. The reducing groups (of grape sugar and fruit sugar) ap- pear to be combined in this compound. The osazones of some of these sugars split off glyoxalosazone when treated with alkalies (B. 29, R. 991). Unorganized ferments, such as diastase and synaptase or emiilsin (contained in sweet and bitter almonds), acting upon the saccharides produce hydrolysis. Inver- tin (changing a dextro-gyratory sugar solution into laevo- rotatory invert sugar), ptyalin (the ferment of saliva), trypsin, pepsin, and other animal secretions exert a like action. When the di- and poly-saccharides are heated with water and a little acid they undergo hydrolysis. Its rapidity, according to Ostwald, bears a close relation to the affinity of the acids (Jour. pr. Chem. (2), 31, 307). Certain inorganic salts, and also glycerol, are capable of inverting cane sugar (B. 29, R. 950; 27, R. 574)- Prolonged heating with acids causes reversion ; the glucoses (especially fructose) undergo a retrogressive condensation to dextrine-like substances (B. 23, 2094). Cane Sugar, Saccharose, Sac char obiose, CuHjjOu, the most im- portant of the sugars, occurs in the juice of many plants, chiefly in sugar cane (Saccharum officinaruni) (20 per cent, of the juice), in some varieties of maple, and in beet-roots {Beta maritimd) (10-20 per cent. ), from which it is prepared on a commercial scale; and also in the seeds 574 ORGANIC CHEMISTRY. of some plants. While the hexoses occur mainly in fruits, cane sugar is usually contained in the stalks of plants. Historical. Sugar has been obtained from sugar cane from the earliest times. In the middle ages sugar cane was a rarity in Germany ; it was only after the discovery of America that it was gradually introduced as a sweetening agent. In 1747 Marg- graf,* in Berlin, discovered cane sugar in beet-roots; his observations became the basis of the beet-sugar industry. In 1801 Achard, in Silesia, erected the first beet-sugar factory. The continental blockade forced by Napoleon I hastened the development of the new industry, which during the last fifty years has attained a constantly increasing importance in Germany. This country produces about one-fourth of the total sugar yield of the world. In the year 1891-92, 403 factories consumed 9,488,002 tons (I ton = 1000 kilos) of beets, which were obtained from 164,774 hectares, and gave to commerce 1,144,368 tons of beet-sugar, from which the country gathered 72,000,000 M. revenue. f Technical Preparation. \ The cane sugar is best removed from the cane and from the finely divided beets by the diffusion process. The saccharine juice diffuses through the cell walls, whereas the colloids in the latter remain behind. The filtered sap is heated to 80-90 with milk of lime, to saturate the acids, and precipitate the albuminoid substances. The juice is next saturated with carbon dioxide, phosphoric acid, or SO 2 (arresting fermentation), filtered through animal charcoal, concentrated, and further evaporated in vacuum pans to a thick syrup, out of which the solid sugar separates on cooling. The raw sugar obtained in this man- ner is further purified with a pure sugar solution, in the centrifugal machine, etc. refined sugar. Sugar may be obtained from the syrupy mother liquor the molasses, which cannot be brought to crystallization : (1) By osmosis, depending upon diffusion through parchment paper, in apparatus similar to filter presses. (2) By washing (elution) (Scheibler, 1865). The sparingly soluble saccharates of lime and strontium are obtained from the molasses (see below) and these are freed from impurities by washing with water or dilute alcohol (elution). The purified saccharates are afterwards decomposed by carbon dioxide, and the juice which is then obtained, after the above plan, is further worked up. The molasses is also worked up into rum (p. 122). Properties. When its solutions are evaporated slowly cane sugar separates in large monoclinic prisms, and dissolves in ^ part water of medium temperature; it dissolves with difficulty in alcohol. Its sp. gr. equals 1.606. Its real rotatory power, A D , at 20 is +66.5 (B. 17, 1757). Cane sugar melts at 160, and on cooling solidifies to an amorphous glassy mass ; in time this again becomes crystalline and non-transparent. At 190-200 it changes to a brown non- crystallizable mass, called caramel, which finds application in coloring liquors. The quantity of sugar in solution may be determined by polariza- tion, using the apparatus of Soleil- Ventzke-Scheibler, or the half-shadow * Ein Jahrhundert chemischer Forschung unter dem Schirme der Hohenzollern, von A. W. Hofmann, 1881. f Statistisches Jahrbuch ftir das deutsche Reich, herausgegeben von Kaiserlichen statistischen Amt. 14. Jahrgang 1893. S. 24, 174. JHdb. d. chem. Technologic, Ferd. Fischer, 1893. S. 851-888. MILK SUGAR. 575 instrument devised by Schmidt and Hansch (B. 27, 2282), as well as by means of the saccharimeter of Brix. Transformations and Constitution. Cane sugar decomposes into d-glucose and d-laevulose (invert sugar) when boiled with dilute acids. Ferments also hydrolyze it. It is only after this occurs that it is capable of reducing Fehling's solution. Mixed with concentrated sulphuric acid it is converted into a black, humus-like body. d-Sac- charic acid, tartaric add and oxalic acid are formed when it is boiled with nitric acid. Cane sugar heated to 160 with an excess of acetic anhydride gives octacetyl ester, C 12 H U O 3 (O . C 2 H 3 O) 8 . This latter fact and the failure of cane sugar to reduce Fehling's solution under ordinary conditions are made to appear in the following formulas: I. (Tollens) , CH - O CH 2 OH II. (E. Fischer) / CH - O CH,OH- VJ.A . WJ..L I \^ i v^nv^ CH.OH /CH.OH \CH.OH /CH.OH O I O I \ I O I i CH.OH y CH.OH \CH \ CH.OH \ CH . OH \ CH CHOH \ CH \CH 2 CH 2 OH CH 2 OH CH 2 OH Cane-sugar yields saccharates with the bases. Alcohol will precipitate the mono- basic saccharate, C 12 H 22 O n . CaO -(- 2H 2 O. The tribasic saccharate, Cj 2 H 22 O n .- 3CaO, is not readily soluble in water (B. 16, 2764). Strontium and barium give perfectly similar saccharates (B. 16, 984) (p. 574). The tetranitrale, C 12 H, 8 (NO 2 ) 4 - O u> explodes violently. Milk Sugar, Lactose, Lactobiose, C 12 H 22 O n -f- H 2 O, occurs in the milk of mammals, in the amniotic liquor of cows, and in certain pathological secretions. Fabriccio Bartoletti, of Bologna, discovered it in 1615. Milk sugar is prepared from whey. This is evaporated to the point of crystalliza- tion, and the sugar which separates purified by repeated crystallization. Milk sugar crystallizes in white, hard, rhombic prisms. It becomes anhydrous at 140, and melts with decomposition at 205. It is soluble in 6 parts cold or 2^ parts hot water, has a faint sweet taste, and is insoluble in alcohol. Its aqueous solution is dextro- rotatory and exhibits bi-rotation (p. 549). It resembles the hexoses in reducing ammoniacal silver solutions; this it effects even in the cold, but in case of alkaline copper solutions boiling is necessary to reach the desired end. Transformations and Constitution. Milk sugar yields galactose and d-glucose when it is heated with dilute acids ; it ferments with difficulty with yeast, but under- goes the lactic fermentation with great readiness (p. 335). Nitric acid oxidizes it to d-saccharic acid and mucic acid. Bromine water converts it into lactobionic acid, C 12 H 22 O, 2 , which is changed to d-gluconic acid and d-galactose upon digesting it with acids (B. 22, 362). ORGANIC CHEMISTRY. Lactose Carboxylic Acid, C 12 H 23 O n . CO 2 H, is produced by the addition of hydro- cyanic acid. It decomposes into d-glucoheptonic acid (p. 568) and d-g'alactose (A. 272,198). Compare isosaccharin, p. 537. / > /^;zy/Z^c-/^a2^^C 12 H 20 O 9 (N 2 HC 6 H 5 ) 2 , melts at 200 (B. 20, 829). Octoacetyl Lactose, C 12 H 14 O 3 [OCO . CH 3 ] 8 , melts al 95-100 (B. 25, 1453). These transformations can be understood from the follow- ing formula of milk sugar : CH 2 OH . CH . OH . CH[CHOH] 2 CH O CH 2 [CH . OH] 4 CHO. Milk sugar forms crystalline derivatives with the nitrate and sulphate of amido- guanidine (B. 28,2614). Maltose, Malt Sugar, Maltobiose, C^H^On -f- H 2 O, is a variety of sugar formed, together with dextrine, by the action of malt diastase (p. 122) upon starch (in the mash of whiskey and beer). It is capa- ble of direct fermentation. It is also an intermediate product in the action of dilute sulphuric acid upon starch, and of ferments (diastase, saliva, pancreas) upon glycogen (p. 578). Maltose is usually obtained in the form of crystalline crusts, com- posed of hard, white needles; [a] = 137 (B. 28, R. 990), and can be obtained from starch by means of diastase (A. 220, 209). Transformations. It was formerly believed that maltose could be directly fer- mented by yeast. It appears, however, that there is present a second enzyme (along with invertin, which does not hydrolyze maltose) in the yeast. This (glucase ?) decomposes the maltose into glucose (B. 29, R. 663). It reduces Fehling's solution only in the presence of grape sugar, which it resembles very closely (A. 220, 220). Diastase does not exert any further change upon maltose ; when boiled with dilute acids, it absorbs water and passes completely into d-glucose or grape sugar. Nitric acid oxidizes it to d-saccharic acid, while chlorine changes it to malto-bionic acid, C 12 H 22 O I2 . This yields grape sugar and d-gluconic acid when it is heated with acids. Hydrocyanic acid transforms it into maltose carboxylic acid, C 12 H 23 O n . CO 2 H, which decomposes into d-glucose and d glucoheptonic acid (A. 272, 200). When boiled with lime water, it forms Isosaccharin (p. 537)* Octoacet-maltose, C 12 H U O 3 (OCO . CH 3 ) 8 , melts at 156 (A. 220, 216; B. 28, 1019). Phenylmaltosazone melts at 206 (B. 20, 831). Maltose and milk sugar possess the same structural formula (B. 22, 1941). The following saccharobioses are less important: Isomaltose, C 12 H 22 O n , isomeric with maltose, results from the action of hydrochloric acid upon d-glucose (B. 28, 3024), and in the mashing process (B. 25, R. 577) ; [a] D = -f- 70 (B. 29, R. 991). Yeast does not ferment it ; diastase converts it into maltose. Its osazone melts at I50-I53 - Mycose, C 12 H 22 O n -f 2H 2 O, Trehalose (B. 24, R. 554; 26, 1332), occurs in several species of fungi e. g. , in Boletus edulis (B. 27, R. 51 1), in ergot of rye, and in the oriental Trehala. Acids convert it into d-glucose (B. 26, 3094). Melibiose, C 12 H 22 O U , is produced in the hydrolysis of melitriose. Further hydrolysis converts it into d-glucose and d-galactose (B. 22, 3118; 23, 1438, 3066). Turanose, C 12 H 22 O U , a white mass, [a] D -f- 65 to -(- 68, is formed along with d-glucose in the partial hydrolysis of melezitose. Its osazone melts at 215-220 (B. 27, 2488). Agavose, C 12 H 22 O H , is obtained from the stalks of Agave americana (B. 26, R. 189). Lupeose, C 12 H 22 O n , is contained in certain seeds (B. 25, 2213). POLYSACCHARIDES. 577 B. TRISACCHARIDES, SACCHAROTRIOSES. Melitose, Raffinose, C 18 H 32 O 16 -f 5H. 2 O, Melitriose (B. 21, 1569) [] D = 104. It occurs in rather large quantity in Australian manna (varieties of Eucalyptus), in the flour of cotton seeds, in small amounts in sugar beets, and being more soluble than cane sugar, it accumulates in the molasses in the sugar manufacture. From this it crystallizes out with the sugar (A. 232, 173). Its crystals have peculiar 'terminal points, and show strong rotatory power (Plus sugar). To determine the raffinose quantitatively consult B. 19, 2872, 3116. By hydrolysis it yields fructose and meiibiose (B. 22, 1678 ; 23, R. 103). Melezitose, C, 8 H 32 O 16 4- 2H 2 O, occurs in the juice of Pinus larix, and in the Persian manna. It resembles cane sugar very much. It is distinguished from the latter by its greater rotatory power (B. 26, R 694), and in not being so sweet to the taste. It mehs at 148 when anhydrous. It is also a triose (B. 22, R. 759). It decomposes by partial hydrolysis into d-glucose and turanose (B. 27, 2488). Stachyose, C 18 H 32 O 16 , is obtained from Stacliys tuberifera (B. 24, 2705). C. POLYSACCHARIDES. It is very probable that the polysaccharides having the empirical formula C 6 H 10 O 5 , really possess a much higher molecular weight, (C 6 H ]0 O 5 ) n . They differ much more from the hexoses than the di-and tn-saccharides. They are, as a general thing, amorphous, dissolve with difficulty in water, and lack most of the chemical characteristics of the hexoses. By hydrolysis, that is when boiling them with dilute acids, or under the influence of ferments, (p. 519), nearly all are finally broken up into monoses (see dextrine). Their alcoholic nature is shown in their ability to form acetyl and nitric esters. They may be classified as starches, gums and cellulose. There are certain gums, like cherry gum and beechwood gum, which yield pen- toses by hydrolysis. They are, therefore, called flentosanes to distinguish them from the glucosanes the polysaccharides, which break down into glucoses when they are hydrolyzed (B. 27, 2722). Starches. (i) Starch, Amylum, (C 6 H 10 O 5 \, is found in the cells of many plants, in the form of circular or elongated microscopic granules, having an organized structure. The size of the granules varies, in different plants, from 0.002-0.185 mm. Air-dried starch contains 10 20 per cent, of water; dried over sulphuric acid it retains some water, which is only removed at 100. Starch granules are insoluble in cold water and alcohol. When heated with water they swell up at 50, burst, partially dissolve, and form starch paste, which turns the plane of polarization to the right. The soluble portion is called granufose, the insoluble, starch cellulose. Alcohol precipitates a white powder soluble starch from the aqueous solution. The blue colora- 49 578 ORGANIC CHEMISTRY. tion produced by iodine is characteristic of starch, both the soluble variety and that contained in the granules (B. 25, 1237 ; 27, R. 602 ; 28, 385, 783). Heat discharges the coloration, but it reappears on cooling. Consult B. 28, R. 1025, for a quantitative, colorimetric method for the determination of starch. Boiling dilute acids convert starch into dextrine and d-glucose (KirchhorT, 1811). When heated from 160-200 it changes to dex- trine. Malt diastase changes it to dextrine, maltose, and isomaltose (P- 576) (B- 27, 293). This is a reaction which is technically con- ducted on a large scale in the manufacture of alcohol from starch (p. 122). (2) Paramyluni) (CgH 10 O 5 ) n , occurs in the infusoria Euglena viridis. It is not colored by iodine, and is soluble in potassium hydroxide. (3) Lichenine, (C 6 H 10 O 5 ) n , moss-starch, occurs in many lichens, and in Iceland moss ( Cetraria islandica]. Iodine imparts a dirty blue color to it. It yields d-glucose when boiled with dilute acids. (4) Inulin is found in the roots of dahlia, in chicory, and in many Composite (like Inn la heleniuni}. Iodine gives it a yellow color. When boiled with water it is completely changed to d-fructose. (5) Glycogen, (C 6 H 10 O 5 ) n , animal starch, occurs in the liver of mammals. Boiling with dilute acids causes it to revert to d-glucose, and ferments change it to maltose. The Gums, (C 6 H 1( jO 5 ) n . These are amorphous, transparent sub- stances widely disseminated in plants; they form sticky masses with water and are precipitated by alcohol. They are odorless and taste- less. Some of them yield clear solutions with water, while others swell up in that menstruum and will not filter through paper. The first are called the real gums and the second vegetable mucilages. Nitric acid oxidizes them to mucic and oxalic acids. Dextrine, Starch Gum, Letocome. By this name are understood substances readily soluble in water and precipitated by alcohol ; they appear as by-products in the conversion of starch into dextrine, e. g., heating starch alone from 170-240, or by heating it with dilute sulphuric acid. Different modifications arise in this treatment : amylo- dextrine, erythrodcxtrine, achroodextrine ; they have received little study (B. 28, R. 987; 29, R. 41). They are gummy, amorphous masses, whose aqueous solutions are dextro-rotatory, hence the name dextrine. They do not reduce Fehling's solution, even on boiling, and are incapable of direct fermentation ; in the presence of diastase, how- ever, they can be fermented by yeast (p. 122). They are then con- verted into d-glucose. They yield the same product when boiled with dilute acids. The dextrines unite with phenylhydrazine (B. 26, 2933). The yeast gum, present in yeast cells, has been isolated (B. 27, 925). Dextrine is prepared commercially by moistening starch with two per cent, nitric acid, allowing it to dry in the air, and then heating it to IIO. It is employed as a substitute for gum (B. 23, 2104). Arabin Gum exudes from many plants, and solidifies to a transparent, glassy, amorphous mass, which dissolves in water to a clear solution. Gum arable or gum Senegal consists of the potassium and calcium salts of arabic acid. The latter can CELLULOSE. 579 be obtained pure by adding hydrochloric acid and alcohol to the solution. It is then precipitated as a white, amorphous mass, which becomes glassy at 1 00, and possesses the composition (C 6 H 10 O 5 ) 2 -f H 2 O. It forms compounds with nearly all the bases ; these dissolve readily in water. Some gum varieties, e. g. , gum arabic, yield galactose in considerable quantity when boiled with dilute sulphuric acid ; and with nitric acid they are converted into mucic acid ; others (like cherry gum) are transformed on boiling with sulphuric acid into 1-arabinose, C 5 H, O 5 (p. 536), and into oxalic acid, not mucic acid, by nitric acid. The gum, extracted from beechwood by alkalies and precipitation with acids, is converted into xylose ^p. 536) by hydrolytic decomposition. Hence these gums must be regarded as pentosanes (p. 577) (B. 27, 2722). Bassorin, vegetable gum, constitutes the chief ingredient of gum tragacanth, Bassora gum, and of cherry and plum gums (which last also contain arabin). It swells up in water, forming a mucilaginous liquid, which cannot be filtered ; it dis- solves very readily in alkalies. Pectine substances (from TTT/KTOS, coagulated) occur in fruit juices, e. #., apple, cher- ries, etc. They cause these, under suitable conditions, to gelatinize. They are closely allied to the vegetable gums, and may be regarded as oxy vegetable gums (A. 286, 278; B. 28, 2609). Cellulose, (C 12 H 20 O 10 ) X , Wood Fibre, Ltgnose, forms the principal ingredient of the cell membranes of all plants, and exhibits an organ- ized structure. To obtain it pure, plant fibre or, better, wadding is treated successively with dilute potash, dilute hydrochloric acid, water, alcohol, and ether, to remove all admixtures (incrustiug substances). Cellulose remains then as a white, amorphous mass. Fine, so-called Swedish, filter paper consists almost entirely of pure cellulose, which can readily be made very combustible by the addition of nitrocellu- lose (B. 27, R. 526). Cellulose is insoluble in most of the usual solvents, but dissolves without change in an ammoniacal copper solution. Acids, various salts of the alkalies and sugar precipitate it as a gelatinous mass from such a solution. After washing with alcohol it is a white, amorphous powder. Cellulose swells up in concentrated sulphuric acid and dis- solves, yielding a paste from which water precipitates a starch-like compound (amyloid), which is colored blue by iodine. After the acid has acted for some time the cellulose dissolves to form dextrine, which passes into grape sugar, when the solution is diluted with water and then boiled. The compound C 12 H 14 O4(OCOCH 3 ) 6 , an amorphous mass, is produced on heating cellulose with acetic anhydride to 180. Cellulose is used in making paper, oxalic acid (p. 432), parchment paper, gun cotton, smokeless powder, and celluloid. So-called parchment paper (vegetable parchment) is prepared by immersing unsized filter paper in sulphuric acid (diluted one-half with water) and then washing it with water. It is very similar to ordinary parchment, and is largely employed. Cold, concentrated nitric acid, or, what is better, a mixture of nitric and sulphuric acids, converts cellulose or cotton into esters or so-called nitro-celluloscs. The resulting products exhibit varying properties, depending upon their method of formation. Pure cotton dipped for a period of three to ten minutes into a cold mix- 580 ORGANIC CHEMISTRY. ture of iHNO 3 and 2~3H 2 SO 4 , then carefully washed with water, gives gun cotton (pyroxylin). This is insoluble in alcohol and ether or even in a mixture of the two. It explodes violently if fired in an enclosed space, either by a blow or percussion. It burns energetically when ignited in the air, but does not explode. Cotton exposed for some time to the action of a warm mixture of 20 parts pulverized nitre and 30 parts concentrated sulphuric acid becomes soluble pyroxylin, which dissolves in ether con- taining a little alcohol. The solution, termed collodion, leaves the pyroxylin, on evaporation, in the form of a thin, transparent film, not soluble in water. It is em- ployed in covering wounds and in photography. In composition gun cotton is cellulose hexa-nitrate , C ]2 H U (O . NO 2 ) 6 O 4 , whereas the pyroxylin, soluble in ether and alcohol, is essentially a tetra-nitrate, C 12 H 16 (O . - NO 2 ) 4 O 6 , and * penta-nitrate , C 12 H,.(O. NO 2 ) 5 O 5 (B. 13, 186). Collodion dissolved in nitroglycerol (equal parts) yields explosive gelatine or smokeless powder (B. 27, R. 537). Celluloid is a mixture of nitrocellulose and camphor. It is a hard, gummy mass. It possesses the disadvantage, from a technical standpoint, that it burns very ener- getically when it has been once ignited. ANIMAL SUBSTANCES OF UNKNOWN CONSTITUTION. Now that the description of the aliphatic bodies has been con- cluded, certain substances of animal origin will be mentioned. Their exhaustive treatment properly belongs in the province of physiological chemistry. It is especially noteworthy that very frequently well-known amido-acidsof the aliphatic series are found among the decomposition products of these rather enigmatical bodies. Many of the substances described in the following pages occur, both in the vegetable and ani- mal kingdoms, in closely related modifications of uncertain constitu- tion, henyl-acetic acid, C 6 H 5 CH 2 . COOH, fi-oxyphenyl-propionic add, HO[4]C 6 H^[i]CH 2 . CH 2 . CO 2 H, phenol, C 6 H 3 OH, indol, C 6 H 4 CH ' skat l or katol-carboxylic acid, C 6 H 4 j [^jJt?j^C . CO 2 H, and skatol-acetic acid, i H ( R 22 > Basic compounds also result in this decomposition. These are the diamines and imines of the paraffin series, and have been called ptomaines or toxines (p. 310). Indol and skatol have also been obtained from albumin by the action of caustic potash. Certain pathogenic micro-organisms, as diphtheria and anthrax bacilli, produce a decomposition that is far more extended, and results in the formation of poisonous substances somewhat similar to albumin and peptone, which have been termed toxalbuinins ; these lose their toxic properties when their aqueous solutions are heated (B. 23, R. 251). The nitrogenous derivatives of albumin, voided with urine, can not in general be obtained artificially from the albuminous bodies. The organism, by oxidation and decomposition, changes albumin into an ammonium salt, which is then further syn- thetically worked up, chiefly in the liver, to urea, uric acid, and other amido-bodies. 582 ORGANIC CHEMISTRY. The albuminates are usually insoluble in water. Their presence in the juices or fluids of the living organism is entirely due to the pres- ence of salts and other substances, which are but partly understood. They are insoluble in alcohol and ether ; most of them are precipitated on boiling in weak acetic acid solution, also by acetic acid and potas- sium ferrocyanide, or acetic acid and sodium sulphate, and by certain mineral acids, as well as by salts of the heavy metals. Many albuminous substances are separated from solution by boiling, by alcohol, by mineral acids, etc. They are coagulated. Their solu- bility is entirely changed. This is not the case with the so-called propeptones. Propeptone precipitated by alcohol dissolves after the removal of the latter as readily in water as before the precipitation. Reactions. All albuminous bodies are colored a violet-red on warming with a mer- curic nitrate solution containing a little nitrous acid (this is like tyrosine) (Millon's reagent). A yellow color is produced when they are digested with nitric acid. This becomes a gold yellow on neutralization with ammonia {Xanthoproteic reaction]. The albuminous substances yield beautiful violet- colored solutions on digesting them with fuming sulphuric acid. Caustic potash and copper sulphate also impart a red to violet coloration to albuminous solutions (Biuret reaction] (B. 29, 1354). On the addition of sugar and concentrated sulphuric acid they acquire a red coloration, which on exposure to the air becomes dark violet. If concentrated sulphuric acid be added to the acetic acid solution of albuminous bodies they receive a violet coloration and show a characteristic absorption band in the spectrum. The manner of distinguishing and classifying the various albuminous substances is yet very uncertain. The original albumins, occurring in nature, are albumin, globulin, casein, gluten proteins, etc., while the secondary modifications obtained from them through the agency of chemicals or ferments are : acidalbumins, albuminates, coagulated albumins, fibrins, propeptones, peptones, etc. Many of these modifications result from the breaking-down of the molecule of the original albumin. It is well worth noting in such instances that the decomposition product still maintains the essential character of the albuminous substances just as the starch molecules yield molecules of grape sugar, which, like the starch, continue as carbohydrates. The breaking-down of the original albumin, in the reactions referred to, is proved by the astonishing fall in molecular weight. This has been partly de- termined by the method of Raoult (p. 32) and in part by testing the electric con- ductivity (Skand. Arch. Physiolog. 5, 337). The decomposition is also evidenced by the fact that the proportion of the carbon to the nitrogen in the decomposition product frequently varies from that in the other decomposition product, just as much as it varies between these substances in the parent body (Schmiedeberg, Arch. exp. Path. 39). This decomposition of the albumin molecule is a hydrolytic decompo- sition. See albumin substances, p. 583. In a certain number of secondary albumin modifications ammonia, sulphur, and amido-acids, like leucine and tyrosine, etc., have been split off, without the loss of the essential character of the albumin. Of pre-eminent importance is the fact that the organs of the living animal body have the power of synthesizing the original albumin from the products with lower molecular weights. This is certainly similar to the formation of glycogen the animal starch, from grape sugar, in the liver. Many substances, not all of which have heretofore been classed as albuminous ALBUMINS. 583 substances, split off sugar when treated with acids; they are therefore glucosides* (Z. physiolog. Ch. 12, 389). 1. Albumins, soluble in water, dilute acids and alkalies, dilute and saturated solutions of sodium chloride or magnesium sulphate. Coagulated by heat. Serum-, egg-, milk-, and vegetable albumin belong in this class. Nitrous acid converts egg albumin into yellow desamido-albumin. This is btill digestible. It does not show the biuret reaction (B. 29, 1354). 2. Globulins, insoluble in water, but soluble in dilute solutions of sodium chloride and magnesium sulphate. These solutions are coagulated on boiling. Magnesium sulphate at 30 precipitates them without any alteration in properties. This class contains: Myosin (muscles), fibrinogen (in the living blood), chang- ing under the influence of fibrin ferment to fibrin; fibrin globulin, obtained from fibrin by means of trypsin ; serum globulin ; crystal-lens globulin and vitellin (in the yellow of the egg). 3. Caseins. Milk casein behaves in general like an albuminate (see under 6), but is distinguished by the fact that whey enzyme precipitates it in neutral or feebly acid solutions in the presence of soluble calcium compounds. This is not the case wiih the albuminate (B. 29, R. 913). The casein of milk appears also to be combined with a phosphorus-containing body, e.g., with nuclein. For this reason some writers class casein with the nucleo-albumins. Caseins also occur in plants. 4. The Gluten Proteins are characterized by their physical properties. In the hydrous state they are pasty, elastic masses. They only occur in wheat flour. Here they constitute the chief essential for bread-making. Gluten is insoluble in water, and sparingly soluble in water containing a very little dilute acid or alkali. Its solubility in alcohol (60-70 volume percent.) is very characteristic. Some gluten proteins when decomposed yield large quantities of glutaminic acid. Thus, Ritt- hausen, obtained not less than 25 per cent, of glutaminic acid from mucedin. 5. Acid Albumins or Syntonins are insoluble in -water and salts, soluble in hydro- chloric acid or a soda solution, do not expel carbonic acid horn, calcium carbonate, and are precipitated in acid solution by neutral metallic salts of the alkalies and alkaline earths. Caustic alkali converts them into albuminate. The acid albumins are produced on treating the albumins, globulins, etc., with hydochloric acid, or with other acids (B. 28, R. 858). 6. Albuminates, insoluble in water and salts, readily soluble in dilute acids and a soda solution, expel carbonic acid from calcium carbonate. They can be precipi- tated without alteration from acid, as well as alkaline, solutions by saturation with solutions of neutral salts of the alkalies and alkaline earths. The albuminates are produced when albumin, globulin, etc., are treated wMi caustic alkali. 7. Coagulated Albuminous Substances. They are insoluble in water and salt solutions, and scarcely soluble in dilute acids. They are obtained by heating other albumins, or by the addition of alcohol, certain mineral acids and metallic salts. 8. Fibrins, insoluble in water, scarcely soluble in a salt solution, and in other salts, or in dilute acids, formed from globulin by a ferment in discharged blood. The process of blood coagulation is expressed according to the investigations of Schmiede- berg (Arch. exp. Path. 31, 8) by the following equation : (C 111 H 168 N 30 S0 35 ) 2 + H 2 = C 108 H ]fi2 N0 30 S0 34 + C 1U H 176 N 30 SO 37 . Fibrinogen Fibrin Fibrinoglobulin. 9. Propeptones or Albumoses (B. 29, R. 518). Certain modifications are produced by the action of the enzymes of the gastric juice or pepsine upon the albu- minous bodies. This is largely due to the hydrolytic decomposition induced in the process of digestion. They can be precipitated by a saturated ammonium sulphate solution at 30, and also at higher temperatures. " The albumoses cannot be coag- * The Physiology of the Carbohydrates, by Pavy. 584 ORGANIC CHEMISTRY. ulated either by boiling their neutral or acidulated aqueous solutions, nor by the pro- longed action of alcohol upon them, although they are insoluble in strong alcohol, and are precipitated by the latter." * They are partly soluble in water, and partly insoluble. They resemble the albu- mins and globulins very much, and by prolonged digestion they finally pass into 10. Peptones, which are perfectly soluble in water, acids, alkalies and salts of the light metals. They cannot be separated from their solutions either by heat, nitric acid, by acetic acid and ferrocyanide of potassium, or by ammonium sulphate. Phosphotungstic acid frequently precipitates the peptones in the presence of hydro- chloric acid, mercuric chloride, basic lead acetate, alcohol, etc., incompletely. The albuminous substances, when acted upon by pepsine and dilute hydrochloric acid at 30-40, are dissolved, completely digested, and at first are converted into syntonins or acid albumins, then into albumoses or propeptones^ and finally into so- called peptones, which dissolve readily in water, are not coagulated by heat, and are not precipitated by most reagents (B. 16, 1152; 17, R. 79). For the molecular weight and constitution of the peptones consult B. 25, R. 643 ; 26, R. 22. The enzyme of pancreas and the ferments of decay produce real peptone from albumin. It is noteworthy that albumin is changed by water above 100, best in the presence of a small quantity of a mineral acid, into albumoses and peptone. It is very certain that the peptones result from the hydrolytic decomposition of albumin, and in the organ- ism again revert to coagulable albumin. There is also a series of bodies more or less closely related to albumin ; some are of a more complex structure than albumin itself, because they are albumin com- pounds. Others show the character of a more or less advanced stage of decomposi- tion of the albumin molecule. In the first class we find : (a) The albumin glucosides. These have received mention. Then follows the large family of mucus bodies e. g., the group of mucin, of mucinogen, of mucolds^ and of the hyalogens. These represent compounds of the albuminous substances with the carbohydrates. (b) Nuclei'n. This occurs in cell-nuclei. It yields albumin and nucleic acids by hydrolysis. These are found in the nucleln bases, such as xanthine, guanine, ade- nine, hypoxanthine, and even sometimes carbohydrates, linked in an ether-like form very probably with phosphoric acid. The very varying composition of the nucleins would indicate a large family, which would attach itself to the so-called nucleoalbu- mins. See B. 27, 2215, for the decomposition of nucleic acid (adenylic acid] by acid. (c) Hemoglobin possesses great importance from a physiological standpoint. It has been pretty thoroughly studied chemically. HEMOGLOBINS. The oxyhamoghbins are found in the arterial blood of animals and may be obtained in crystalline form from the blood corpuscles by treatment with a solution of sodium chloride and ether, and the addition of alcohol. The different oxyhsemoglobins, isolated from the blood of various animals, exhibit some variations, especially in crystalline form. Their elementary composition approximates that of albumin very closely. It differs, however, by an iron content of 0.4 per cent. If the molecular weight of haemoglobin be calculated on the supposition that it contains an atom of iron, the value obtained exceeds 13,000. The haemoglobins are bright red, crys- talline powders, very soluble in cold water, and are precipitated in crystalline form by alcohol. When the aqueous solution of oxyhaemoglobin is placed under the air- pump or when it is exposed to the agency of reducing agents (ammonium sulphide) it parts with oxygen and becomes hemoglobin. The latter is also present in venous * Lehrbuch der phys. Chemie von R. Neumeister, S. 229 (1897). GELATINOUS TISSUES. 585 blood, and may be separated out in a crystalline form (B. ig, 128). Its aqueous solution absorbs oxygen very rapidly from the air, and reverts again to oxyhaemo- globin. Both bodies in aqueous solution exhibit characteristic absorption spectra, whereby they may be easily distinguished. If carbon monoxide be conducted into the oxyhsemoglobin solution, oxygen is also displaced and hemoglobin-carbon monoxide formed. This can be obtained in large crystals with a bluish color. This explains the poisonous action of carbon monoxide. The bluish-red solution of haemoglobin-carbon monoxide shows two characteristic absorption spectra. These do not disappear upon the addition of ammonium sulphide (distinction from oxyhaemoglobin). On heating to 70, or through the action of acids or alkalies, oxyhaemoglobin is split up into albuminous bodies, fatty acids and the dye-stuff // c? inatoch roniogen, which in contact with free oxygen changes to hamatin, which in a dry condition is a dark brown powder. It contains 9 per cent, of iron, and, as it appears, corresponds to the formula, C 34 H 34 FeN 4 O 5 . The addition of a drop of glacial acetic acid and very little salt to oxyhasmoglobin (or dried blood) aided by heat, produces microscopic reddish- brown crystals of haemin (haematin hydrochloride), C 32 H 31 N 4 O 3 FeCl (B. 29, 2877) ; alkalies separate hnematin, C 32 H 31 N 4 O 3 FeOH, again from it. The production of these crystals serves as a delicate reaction for the detection of blood. The great physiological importance of haemoglobin is evident from the fact that in the lungs it removes the oxygen from inhaled air, holds it loosely combined, and passes it over to the various organs in the course of circulation that is, it renders the oxidation processes possible by transferring oxygen to them. Hydrogen bromide con- verts haemin into /fo/;zrt/0/0r//y//-/,C ]6 H, 8 N 2 O 3 (Nencki and Sieber, B. 21, R. 433). This is closely allied to Phylloporphvrin, C 16 H 18 N 2 O. This is obtained by fusing phyllocyanin with caustic soda. Chlorophyll treated with concentrated acids yields phyllocyanin. The absorption spectra of the neutral and acid solutions of both bodies are identical, and only differ in that " the lines of haemato-porphyrin are moved a shade toward the red." The two bodies probably bear the same relation to each other that are observed existing between purpurine and oxyanthraquinone. That is, they are different stages of oxidation of one and the same nucleus substance (E. Schunck and L. Marchlewski, A. 290, 306 ; B. 29, 2877). This kinship corresponds to an anal- ogous physiological action. Consequently haemoglobin attracts free oxygen and surrenders it in the organs when it is required, whereas chlorophyll liberates oxygen from carbonic acid and water in order to present it to the living animal. As the lower fungi, "without chlorophyll, are capable of building up carbohydrates, fats, and albumins from many molecules which contain the groups CH ? and CHOH, there seems to be no doubt that synthetic work can be executed by the living cell substance to which (in the green portion of plants) the requisite atomic groups are presented by processes of reduction (privately communicated by E. Pfliiger). The following substances are produced by the decomposition of albuminous bodies. They still retain the albumin character, but in a somewhat modified form : GELATINOUS TISSUES AND GELATINES. These are mostly nitrogenous, organized substances, which on boil- ing with water are converted into gelatines (glue). Glutin, gelatine, swells up in cold water, and on boiling dissolves to a thin laevo- rotatory solution, which gelatinizes on cooling. By the addition of concentrated acetic acid or protracted boiling with a little nitric acid, the solution loses the prop- erty of gelatinizing (liquid gelatine). Tannic acid precipitates from the aqueous solution gelatine tannate, a yellowish, glutinous precipitate. The substances yield- ing gelatine combine also with tannic acid, withdrawing the latter completely from its solutions and forming leather. 586 ORGANIC CHEMISTRY. Glycocoll, leucine, and other amido-fatty acids are the principal substances pro- duced on boiling gelatine with dilute sulphuric acid or alkalies. When glutin is heated with hydrochloric acid on a water-bath there results a glutin-peptone chlor- hydrate, soluble in anhydrous methyl and ethyl alcohol. The glutin peptones can be obtained from it. Dry distillation produces pyrrol and pyridme bases (bone-oil). Glutin peptone contains, as shown by its behavior with nitrous acid, at least three different kinds of N-atoms. One of these exists as NH 2 , the second as NH, and the third as a tertiary N-atom (B. 29, 1084). Alcoholic hydrochloric acid changes gelatine into a compound that nitrous acid converts into a substance, C 5 H 6 N 2 O 3 , very similar to the diazo fatty-acids. It may be that it represents diazo-oxyacrylic ester, CN 2 : C(OH) . CO 2 . C 2 H 5 (B. 19, 850). Although glutin in its composition is very similar to albumin, it cannot replace the specific functions of albumin in the animal metabolism. Bone-, fat-, and cartilaginous tissues are produced according as certain substances are arranged in their gelatinous parts by lime and magnesium salts, or by fats, etc. Chondrin results on boiling ordinary cartilage. It is a mixture of glutin and certain compounds of chondroit-sulphuric acid with gelatine and albuminous bodies on the one side and alkalies on the other (Schmiedeberg : Arch. exp. Pathol. und Pharmakol. 28). Schmiedeberg represents the constitution of chondroit-sulphuric acid as follows : CO . CO . CH 2 . CO . CH 2 . CO . CH 3 CH. N : CH[CHOH] 4 . CO 2 H [CH.OH] 3 CH 2 . . SO 3 H. The acid is very probably a condensation product of sulphuric acid, acetic acid, glycuronic acid and glucosamine. Artificial mixtures of glutin and salts of chon- droit-sulphuric acid give the reactions of so-called chondrin. Chitin belongs to the class of substances present in bone cartilage. It is the chief component of the shells of crabs, lobsters, etc. It is interesting to observe that its nitrogen exists as glucosamine (p. 550), because Ledderhose (Z. phys. Ch. 2, 224) has demonstrated that when chitin is decomposed with hydrochloric acid gluco- samine and acetic acid result. Hence, Schmiedeberg believes that the following equation has value : C 18 H 30 N 2 12 + 4 H 2 == 2C 6 H 13 N0 5 + 3 CH 3 . CO 2 H. Chitin Glucosamine Acetic Acid. Chitin heated to 184 with molten alkali yields acetic acid and chitosan, which breaks down into acetic acid and glucosamine when it is heated with hydrochloric acid (B. 28, 82). The shell substance of the fungi is probably identical with chitin, and the Mycosin, obtained from it by means of caustic potash, is identical with chitosan (B. 28, 821, R. 476). The following are probably disintegrated albumin molecules : Elastin, which differs from albumin in containing less sulphur. Ceratin, horn substance, is the principal ingredient of hair, nails, etc. It con- tains a variable but at times a very high sulphur content (0.7 to 5.0 per cent.) (B. 28, R. 561). Notwithstanding it approximates the percentage composition of albumin very closely, ceratin gives almost the same decomposition products as albumin, e.g., leucine and tyrosine. BILIARY SUBSTANCES. 587 UNORGANIZED FERMENTS OR ENZYMES. Unorganized ferments playing an important part in fermentation, in many processes of decay, and in digestion, appear to be closely related to the albuminous substances. They are soluble in water. Boiling water destroys their activity. Enzymes are the cause of the hydrolysis of glucosides, and in fermentation their role appears to be the decomposition of the polysaccharides, which are to be regarded as glucosides. The configuration of the glucosides (B. 28, 984, 1429) exercises a very definite influence upon the action of the enzyme. The following are of vegetable origin: Invertin, diastase (p. 120), emulsin or synaptase, present in bitter almonds, myrostn, found in mus- tard seeds, papam, etc. In the digestive juices of animals we have pytaline (xruados, saliva) in the saliva, pepsin (Tre/rroc, digested) in the gastric juice, and other enzymes. BILIARY SUBSTANCES. In the bile, the liquid secretion of the liver, which effects the emul- sion and reabsorption of the fats, occur the sodium salts of two peculiar acids, glycocholic and taurocholic ; also lecithin (p. 475), choles- terine and bile pigments bilirubin, biliverdin. Various views prevail in regard to the origin of the latter. The relationship to the albuminous bodies has never been determined. Cholalic Acid, C 2t H 40 O 5 (B. 27, 1339; 28, R. 332; 29, R. 142), melting at 195, when anhydrous, is a monobasic acid. It is obtained together with glycocoll as a de- composition product of glycocholic acid, and with' taurine as a product of the decom- position of taurocholic acid. Glyco- and taurocholic acids exist as sodium salts in the bile. In preparing cholalic acid, choleinic acid, C 24 H 40 O 4 , and /omerism, 50 Allomucic acid, 571 Allophanic acid, 403 Alloxan, 508 Alloxanic acid, 509 Alloxantin, 509 Allyl acetic acid, 284, 346, 481 alcohol. 130, 131, 208, 277 amine, 169 cyanamide, 426 cyanide, 54 ether, 136 ethyl ether, 143 haloids, 106, 142 iodide, 53. 99, 143,277,473 isosulphocyanic ester, 423 malonic acid, 284, 457 mercaptan, 149 mustard oil, 54, 425, 130 rhodonate, 54, 143, 423 succin ; c acid, 467 sulphide. 143, 150 snlphocarbamic ethyl ester, 406 sulphourea, 409 trichloride, 472 urea, 399 Allylene, 97, 99, 215, 465 Allylin, 476 Aluminium alkyls, 186 carbide, 8 1 ethylate, 124 Amalic acid, 510 Amber, 443 Amid-chlorides, 223, 268 Amides, acid, 262 cyclic, 357, 359 Amido-acetal, 316 acetaldehyde, 316 acetic acid, 354 acetoacetic ester, 483 acetone, 319 alanine, 361 barbituric acid, 507 butyric acids, 358, 359 ethyl alcohol, 124, 309 "Iphonic acid, 306 fatty acids, 351 formic acid, 393 fumaric acid, 495 glutaconic acid, 495 glutaramic acid, 493, 501 glutaric acid, 494 guanidine, 415, 550, 576 hydracrylic acid, 481 isethionic acid, 306, 311 isobutyric acid, 219, 357 succinic acid. 486 valeric acid, 358, 357 lactic acid, 481 malonic acid, 486, 497 malonyl urea, 507, 513 methylene acetoacetic ester, 483 . malonic ester, 494 methyl triazole, 415 paraldimine, 206 propionic acid, 206, 356, 448 propyl methyl ketone, 319 pyrotartaric acid. 491 succinic acid, 489 tetrazotic acid, 415 thiazoles, 408 thiolactic acid, 347, 371 uracil, 513 valeraldehyde, 317 valeric acid, 359, 581 valerolactone, 380 Amidoximjes, 223, 271 Amidoxyl nitriles, 206 Amines, 160 Amino-dioxypurin. 516 [Amino-ethan-acid], 354 [Amino-ethanal], 316 592 INDEX. Amino-ethidene succinic ester, 495, 5l succinimide, 495, 501 fatty acids (see Amido-fatty acids). [g-Amino-nonanic acid], 285 Ammelide, 427 Ammeline, 427 Ammonium carbonate, 394 cyanate, 417 Amniotfc" liquid, 575 Amygdalin, 228, 543 Amyl alcohol, 68, 127 glycide ether, 477 . haloids, 140 Amylene glycol, 296 hydrate, 94, 129 ketone anilide, 320 nitrolaniline, 320 Amylenes, 94, 127 Amylo-dextrine, 578 ^fe Amyloid, 579 Amylum, 577 Amyrines, 588 Analysis, elementary, 18 Angelica archangelica, 248, 283 lactone, 362 Angelic acid, 50, 283 Anhydrides of carboxylic acids, 259, 338, 428 Anhydro-enneaheptite, 542 H. Anilido-butyro-lactam, 449 crotonic ester, 363 perchlorcrotonic ester, 449 pyrotartaric acid, 492 succinimide, 449 Aniline, 161 , 492 Anil-pyruvic acid, 371 uvitonic acid, 371 Animal substances, 580 Anthemis nobilis, 283 Anthracene, 74, 75 Antiform, 445 Antimony alkyl compounds, 179 Antipyrine, 256, 363 Anti-tartaric acid, 526 ApocafTelne, 515 Aqua amygdalarum amararutn, 228 Aral)ic acid. 578 Arabin, 578 Arabinose, 534, 536 carboxylic acid, 566 diacetamide, 536^ Arabite, 107, 534 Atabonic acid, 5^7 Arachidic acid, 249, 250 Arachis hypogoea, 285 Arginine, 581 Argol, 525 Aromatic substances, 78 Arrack, 122, 227 Arsertte alkyl compounds, 175 esters, 147 Arsines, 175 Arsinic acids, 178 Arsonic acids, 177 Asparacemic acid, 489 59, 490 aldehyde, 581 Aspara^inimide, 490 Aspartic acid, 490, 501, 581 Asphaltum, 87 Asymmetric carbon atom, 46 Asymmetry, absolute, 49 relative, 49 Aticonic acids, 465 Atomic rearrangement, intramolecular, 52 volume, oo Axial symm'etric configuration, 50 Azelaic acid, 285, 455 Azide carbonic ester, 389 Azimethylene, 206 Azin-succinic ester, 527 Azo-dicarbonamidine, 415 dicarbonic acid, 405 fatty acids, 361 for mam id e, 405 formic acid, 405 oxazoles, 327 tetrazole, 415 Azulmic acid, 437 B BACILLUS acidi loevolactici, 336 boocopricus, 247 butylicus, 473 ethaceticus, 480 subtilis, 247 Bacterium aceti, 244 termo, 296 Baldrianic acid, 248 Barbituric acid, 506 Bass6*rin, 579 Beckmann's transformation, 220, 285 Beechwood gum, 577 Beer, 122 vinegar, 944 Behenic acid, 249, 251 Behenolic acid, 288, 455 Behenoxylic acid, 288, 484 Benzaldehyde, 75, 228, 258 Benzal-glycerol, 476 INDEX. 593 Benzal-loevulinic acid, 380 semicarbazide, 405 Benzene, 74, 96, 528 azocyanacetic ester, 499 sulphonic acid, 135 Benzoic acid, 117, 123, 354 Benzoin, 408 Benzoquinone. 75 Benzosazones, 546 Benzoyl chloride, 258 glycocoll, 354 oxycrotonic estej, 362 piperidine, 359 Benzyl isonitroso acetone, 326 Berberis vulgaris, 487 Beiyllium alkyls, 184 Betalue, 310, 348 aldehyde, 316 Beta rnaritima. 573 vulgaris, 310 Biguanide, 414 Bi-iodo-acetacrylic acid, 380 Bilineurine, 309 rubin, 587 verdin, 587 Bioses, 573 Bis-dialkylazimethylene, 220 dimethylazimethylene, 220, 405 hydrazine carbonyl, 405 Bismuth alkyls, 179 Biuret, 403 reaction, 582 Blood color, 585 Boiling point, determination of, 63 relation to constitution, 64 Boletus edulis, 550, 576 Bombyx processionea, 225 Bone oil, 586 tissue, 586 A Boric esters, 147 Borneol, 568 Boron alkyls, l8o Brain, 476 Brandy, 122 Brassidic acid, 50, 286 Brassylic acid, 286, 455^ Brom-acetal, 200, 316 acetaldehyde, 199, 316 acetic acids, 275 acetoacetic acid, 378 acetol, 215 acetone, 317 acetoxime, 319 acetylbromide, 105 acetylene, 106, 288 acetylurea, 400 acrylic acid, 281 Brom alcoholate, 124, 198 allyl alcohol, 131 anilic acid, 217 butylamine, 311 butyl methyl ketone, 217, 318 butyric acids, 281 cinnamic acids, 50 crotonic acids, 281 ethane, 101, 124, 141 ethines, 104 ethyl amine, 311, 404, 410 malonic acid, 486 phthalimide, 311, 359 ethylene, 95, 101, 302 fumanc acid, 464 imidocarbonic acid ester, 404 lactic acid, 340 kevulinic acid, 381, 528 maleic acid, 451, 464 malonic acid, 440 mesaconic acid. 464 methacrylic acid, 452 ^ methyl ether acid, 202 nitroethane, 157, 204 form, 159, 383, 387 propane, 157, 204 urethane, 157, 204 cenanthic acid, 346 oleic acid, 285 pimelic ester, 492 propiolic ester, 287 propionic ester, 275, 501 propyl amine, 311, 404 methyl ketone. 318 phthalimide, 359 sutcinic acids, 381, 451, 526 succinyl bromide, 458 c trinitromethane, 387 valeric acid, 346 Bromal, 124, 198, 340 Bromalides, 340 Bromhydrin, 474 Bromine determination, 23 Bromoform, 102, 159, 198, 224, 23*, 370, 386 picrin, 159, 387 Bunte's salt, 153 Butalanine, 357 ~Butanal], 196 Butan-dien], 99 Hutandiol], 296 Butandion], 322 Butane diacid chloride], 446 3utane heptacarboxylic ester, 539 pentacarboxylic acid, 539 tetracarboxylic acid, 532 tricarboxylic acid, 518 594 INDEX. Butanes, 84, 85 Butanol diacid], 487 Butanols], 126 iutanolid, 345 Butanon], 2l6 Butanon-acid], 372 Butanon diacid], 499 iutdien carboxylic acid, 288 Butenyloxytricarboxylic acid lactone, 530 [Butine], 98 Butyl acetic acid, 249 acetylene carboxylic acid, 288 alcohols, 126, 208 aldehyde, 126, 196, 208 amine, 167 bromide, 140 chloral, 126, 199, 477, 568 aldol, 477 chlorides, 140 glyceric acid, 480 glycerol, 473 iodides, 140 lactinic acids, 337 mercaptan, 149 nitramines, 171 nitrile, 144 pseudonitrol, 158 sulphide, 149 Butylene glycol, 296 hydrate, 126 Butylenes, 89, 92, 126 Butylidene acetic acid, 284 Butyric acid, 247, 256, 261, 265, 268 fermentation, 548 Butyroin, 297, 318 Butyro lactam, 360 lactone, 276, 345, 360 carboxylic acid, 346, 486 nitrile, 268 Butyrone, 216 Butyronoxime, 220 Butyryl butyric acid, 382 chloride, 259 cyanide, 371 formic acid, 370 CACAO, 514, 515 Cacodyl, 178 compounds, 177 hydroxide, 177 Cadaverine, 313 Cadet's Fluid, 176 Caffeidine, 515 carboxylic acid, 515 Caffeine, 355, 504, 515 Caffinic acid, 515 Caffolin, 515 Calcium carbide, 97, 204 Camphor, 445, 518, 568 glucuronic acid, 569 phorone, 221, 453 Camphoric acid, 445 Camphoronic acid, 445 , 5*8 Canarine, 422 Caoutchouc, 99 Capric acid, 250, 256, 265 aldehyde, 196 Caprinone, 215 Caproic acid, 250, 259, 265 Caprolactone, 346, 493 carboxylic acid, 494 dfcprone, 215 Caprylic acid, 250, 265, 268 Caprylone, 215 oxime, 220 Caramel, 574 Carbamic acid azide, 396 chloride, 396 ester, 394, 403 hydrazide, 405 thiol acid, 406 Carbamides, 396, 398, 505 Carbamide- malonyl guanidine, 506 urea, 507 Carbazide, 389 Carbethoxyl-oxycrotonic ester, 362 Carbinol, 57, 117 Carbmethoxyamido-propionic ester, 448 Carbocyclic compounds, 78 Carbodiimide, 55, 426 Carbohydrates, 572 Carbohydrazide, 405 Carbohydrazidine, 438 Carbon atoms, asymmetric, 45, 68 compounds, acyclic, 77 caibocyclic, 78 optically active, 46, 67 saturated, 38 unsaturated, 38 determination of, 19 dioxide, 122, 226, 244, 383,384 disulphide, 390 dithiol acid, 389, 391 linkage, multiple, 51 single, 37 Carbonic acid (see Carbon dioxide), cyanides, 416 esters, 386 Carbon monosulphide. 236 monothiol acid, 389, 391 INDEX. 595 Carbon monoxide, 75, 76, 8l, 227, 235, 384, 433 decomposition of di- oxosuccinic ester, 528 decomposition of ox- alacetic es:er, 499 haemoglobin, 585 nickel, 236 potassium, 236 oxybromide, 389 oxy chloride, 75, 388 bromide, 389 oxysulphide, 390, 424 tetrachloride, 386 Carbonyl chlo'ride, 388 diurea, 404 Carbo-pyrotritartaric ester, 529 thiacetonine, 409 thialdine, 407 valerolactone carboxylic acid, 487 lactonic acid, 494 Carboxethyl-pseudo-lutidostyril, 496 thiocarbimide, 425 Carboxyl group, 222 Carboxy-g.ilactonic acid, 571 tartronic acid, 528 Carboxylic acids, saturated, 222, 428, 516,531,539 unsaturated, 276, 456 5l8, 533 Carbylamines, 1 66, 225, 236, 263 Carbyl sulphate, 307 Carnauba wax, 257 Carnaubic acid, 588 Carnine, 516 Casein, 582, 583 Celluloid, 580 Cellulose, 211, 214, 579, 580 Ceratin, 586 Ceratoma siliqua, 247 Ceresine, 88 Cerin, 257 Cerotic acid, 130, 249, 251 ceryl ester, 257 Cerotin, 129, 130 Ceryl alcohol, 130, 251 Cetaceum, 257 Cetene, 92 Cetraria islandica, 578 Cetyl alcohol, 92, 129, 257 bromi le, 142 cyanide, 268 ether, 136 iodide, 142 sulphide, 149 Chain isomerism, 41 Chelidonic acid, 496, 503, 538 Cherry gum, 579 Chitin, 586 Chitonic acid, 567 Chitosan, 586 Chlor-acetal, 197, 200, 316 acetaldehyde, 199, 316 acetic acids, 274, 501 aceto-acetic ester, 378, 438 acetol, 217, 300 acetone, 216, 317, 376, 484 acetoxime, 319 acetylene, 106, 288 acetyl urea, 400 acrylic acid, 281 alide, 198, 281, 340 alimide, 206 allyl alcohols, 131 alose, 550 amylarnine, 311 anilic acid, 217 brom-maleic acid, 464 butane-hepta carboxylic ester, 539 butyl aldehydes, 199, 208 amine, 311 butyric acids, 199, 276, 346 carbonic acid, 227 amide, 396 ester. 388, 394, 414 carbon thiol ethyl ester, 393 citramalic acid, 527 citric acid, 539 croton aldehyde, 199 - crotonic acids, 50, 281, 375 cyanogen, 377, 420 ethanes, 103, 141, 302 ethenyl tricarboxylic ester, 517, 539 ethylamine, 311 ethylenes 105, 277 ethyl-imido formyl cyanide, 438 sulphonic acid, 306 formic ester (see Chlor-carbonic acid) fumaric acid, 463, 525 glutaconic acid, 467, 494 hydracrylic acid, 340, 480 hydrin, 474 imido-carbonic ester, 404 isobutyl methyl ketone, 217 crotonic acid, 281, 282, 496 niiroso-acetone, 371 lactic acid, 340, 477 maleic acid, 464 malic acid, 525 malonic ester, 440 methane, or methyl chloride, 141 596 INDEX. Chlor-methyl ether, 202 nitromethane, 157 Chloral, 125, 197, 227, 340, 387, 477 acetamiue, 265 acetone, 318, 382 alcoholate, 124, 198 aldol 477 ammonia, 2o5 cyanhydrin, 350 eth>l acetate, 198 formamide, 227 hydrate, 197, 198 hydroxylamine, 206 oxime, 206 ut ethane, 395 Chlorine determination, 23 Chloroform, 82 Chlorophyll, 585. Chloropicrin, 157, 166, 235, 383, 387 Chloroxalethylin, 436 oxethose, 136 oximUoacetic ester, 438 pentanpenta-carbonic acid, 539 perthiocarbonic acid ester, 393 propiolic acid, 287 propionic acid, 199, 275, 341 propylene, 106, 277 propyl aldehyde, 199, 208 succinic acid, 451, 531, 539 sulphonic acid ester, 146 theophylline, 515 thioncarbonic acid ester, 393 trinitrobenzene, 165 valerolactone, 380 Cholahc acid (cholic acid), 306, 587 Cholestene, 587 Cholesterene, 587 Cholestrophane, 505 Choline, 309 Chondrin, 586 Chondroitic sulphuric acid, 586 Chromogen, 65 Chromophorous group, 65 Cinchomeconic acid, 530 Cinchonic acid, 466, 530 Cinchonicine, 68 Cinchonine, 68, 524 Cineolic acid, 527 Cis, 51 Citracetic acid, 519 brompyrotartaric acids, 451, 452 chlorpyrotartaric acid, 451 conic acid, 76, 97, 464 Citral, 209 Citramalic acid, 527 Citramide, 530 Citrazinic acid, 519, 530 Citric acid, 21 1, 214, 529 Citronellal, 209 Coagulate, 582 Cochlearia armonacia, 425 Cocoa-nut oil, 250, 252 Coffeme, 515 Cognac, 122 Cola-nuts, 515 Collidine, 208, 316 Collodion, 580 Comanic acid, 496 Combustion, heat of, 72 Condensation reactions, 193 Conductivity, electric, 70 Configuration, 49 Conglutin. 357 Coniferin, 543 Coniine, 47, 68, 99 Constitution, 34 Convicin, 59 Conylene, 99 Corn whiskey, 122 Coumalic acid, 362, 367, 467, 496 Coumalin, 362 Coumaric acid, 50 Coumarins, 488 Cow butter, 249 Creatine, 413 Creatinine, 413 Crotonal ammonia, 208 Croton alcohol, 208 aldehyde, 199, 208, 295, 496 oil, 283 Crotonic acid, 50, 53, 208, 276, 277, 281, 342, 369 Crotonyl alcohol, 131, 208 Crotonylene, 97, 98 Crystal alcohol, 123 chloroform, 234 Crystalline lens globulin, 583 Cyamelide, 417 Cyanacetamide, 440 hyclrazide, 440 acetic acid, 274, 440 acetone, 327, 378 amide, 55,411, 412,426 amido carbonic acid, 403 dicarbonic acid, 403 Cyanates, 417 Cyancarbamic acid, 403 carbonic acid esters, 437 Cyanethine, 268 Cyanetholines, 417 Cyan formic acid, 354, 437 glutaric ester, 517 guanidine, 414 Cyanhydrins, 230, 350 INDEX. 597 Cyanic acid, 54, 416 esters, 417 Cyanides and double cyanides, 230 Cyanimido-carbonic acid ester, 438 isonitrosoacetamide, 239, 499 acethydroxamic acid, 499 butyric acid, 484 malonic acid ester, 517 Cyanoform, 517 Cyanogen, 76, 228, 230, 354, 437 bromide, 421 chloride, 420,421 compounds, 228, 266, 349, 370, 416, 436, 440, 449 hydride, 76, 166, 225, 228, 416, 421 iodide, 421 sulphide, 422 Cyanorthoformic ester, 437 oximido acetic acid, 498 butyric acid, 484, 501 propionic acid, 442, 446, 453 succinic ester, 517 uramide, 427 urea, 404 Cyanuric acid, 419, 511 bromide, 421 chloride, 421, 426, 427 iodide, 421 Cyclic compounds, 77 Cycloacetone superoxide, 215 butane, 89 heptane, 89 hexane, 89 paraffin carboxylic acid, 532 .paraffins, 89 pentane, 89 propane, 89 Cystein, 347 Cystin, 347 Cytromytes pfefferianus and glaber, 529 DECAMETHYLENE diamine, 313 [Decan-diacid], 455 [Decandion diacid], 529 Decane. 86 Decylenic acid, 284 Dehydracetcarboxylic acid, 502 Dehydracetic acid, 376, 521 Dehydrochloralimide, 206 -mucic acid, 570 undecylenic acid, 284 Desmotropy, 56 Desoxalic acid. 539 Desoxyfulminuric acid, 239 Deviation of the plane of polarization, 67 Dextrine, 12 1, 578 Dextro-amyl alcohol, 68, 128 asparagine, 490 aspartic acid, 490 glyceric acid, 480 lactic acid, 337 malic acid, 487 mandelic acid, 68, 69 tartaric acid, 68, 525 Dextronic acid, 566 Dextrose, 548 carboxylic acid, 346, 568 Diacetamide, 265 Diacetin, 475 Diaceto acetic ester, 484 adipic acid, 529 dimethyl pimelic acid, 529 fumaric ester, 529 glutaric ester, 529 succinic acid, 376, 528 Diacetonamine, 219, 319 Diacetone alcohol, 318 Diacetone-alkamine, 310 Diacetyl, 322, 484, 527 acetone, 479 creatine, 413 cyanide, 370 dioxime, 327 ethane, 323 -ethylene diamine, 312 hydrazone, 328 osazone, 328 osotetrazone, 328 osotriazone, 328 pentandioxime, 328 pentane, 325 racemic acid, 524 tartaric acid, 526 urea, 401 Diacetylene dicarboxylic acid, 468 glycol, 297 Diacetylenes, 99 Diacipiperazine, 358 Dialdin, 316 Dialkyl amidoketones, 319 hydrazines, 171 nitramine, 171 Diallyl, 99, 520 acetic acid, 284 acetone, 217. 221 dicarboxylic ester, 221 malonic acid, 467 urea, 399 598 INDEX. Diallylin, 476 Dialuric acid, 506 Diamide, 171 Diamido-acetone, 478 caproic acids, 581 malonamide, 499. mesoxalamide, 499 oxal-ethers, 436 propionic acid, 481 pyrazole, 440 succinic acids, 526 [Diamino-butane], 313 ethyl disulphide chlorhydrate, 3" sul phone, 311 Diamino-hexane], 313 Diamino-2-methyl pentane], 313 Diamino-octane], 313 Diamino-pentane], 313 Dianilido-succinic acid, 526 Diastase, 121,573,576,587 Diazo-acetamide, 366 acetic acid, 171, 366, 458 benzene chloride, 438, 499 imide, 468 ethane sulphonic acid, 171 ethoxane, 144 fatty acid esters, 273, 366, 371 guanidine nitrate, 415 methane, 207 oxyacrylic acid ester, 586 paraffins, 207 propionic esters, 371 succinic acid, 501, 526 Diazoles, 321 Dibenzal carbohydrazide, 405 Dibenzoyl-ethane, 446 Dibromacetaldehyde, 198 acetic acid, 275, 458 aceto acetic ester, 378 acetyl, 322 acrylic acid, 282, 452 allylamine, 169 barbituric acid, 509 butane, 303 butyl ketone, 217 butyric acid, 276 caproic acid, 381 crotonic acid, 282, 288 diketo-R-pentene, 381 dinitromethane, 381 ethyl ketol, 478 fumaric acid, 464 glyoxime peroxide, 238 hexane, 303 Dibromhydrin, 474 ketone, 217 Dibromlaevulinic acid, 381 maleic acid, 464 aldehyde, 321 malonic ester, 440 malonyl urea, 499, 509 methyl acetoacetic acid, 378, 465 ether, 202 nitroacetonitrile, 238 nitromethane, 157, 235 nitroparaffins, 157 pentane, 303 propionic acid, 208, 275 pyroracemic acid, 370, 483, 486 stearic acid, 286 succinic acid, 451, 457, 500 succinyl chloride, 458 Dibutyryl, 297, 317 Dicarbamidic acid, 403 Dicarbon-tetracarboxylic ester, 533 Dicarboxyl-glutaconic ester, 533 glutaric ester, 532 Dichloracetal, 197, 198, 200 acetaldehyde, 198, 340 acetic acid, 197, 274, 458 aceto-acetic ester, 378 acetone, 217, 529 acetonic acid, 529 acrylic acids, 282 butyric acid, 276 butyro-lactone, 447 crotonic acid, 282, 288 ethane, 102, 201, 302 -ether, 136, 200, 316 ethyl alcohols, 125, 316 ethylene, 105 glycollic acid ester, 434 hydrin, 130. 217, 474 isobutyl ketone, 217 isopropyl alcohol, 474 lactic acid, 340 maleic acid, 321 derivatives, 321 male'inimide, 448 malonic acid ester, 440 methane (see Methylene chlor- ide), monosulphonic acid, 235 methyl alcohol, 235 ether, 118, 134, 202 sulphonic acid, 393 muconic acid, 467 oxalic ester, 434 propionic acid, 275, 369, 466, 410 propylene, 199, 208 succinic acid, 451 INDEX. 599 Dicyanogen, 437 diamide, 410, 414, 427 diamidine, 414 hydride, 231 Diethoxyacetone, 478 butyric acid, 378 malonic ester, 498 succinic acid, 500 Diethyl acetic acid, 249 acetonitrile, 268 acetylchloride, 259 acetylene glycol dipropionate, 297 allyl carbinol, 131 amido acetic acid, 356 acetone, 319 amine, 167 chlorboride, 165 chlorphosphide, 165 chlorsilicide, 165 butyrolactone, 346 carbinol. 127 cyanamide, 426 dithiophospinic acid, 175 ethane tetracarboxylic ester, 531 ethylene lactic acid, 342 glycollo-nitrile, 350 hydantoin, 402 hydrazine, 171 hydroxylamine, 172 ketone, 216 nitramine, 171 nitrosamine, 170 oxalic acid, 249 oxalo nitrile, 349 oxamic acid, 435 oxamide, 436 oxetone, 478 oxybutyric acid, 342 sulphone di-brommethane, 393 methyl ethyl methane, 218 sulpho urea, 409 thiourea, 409 urea, 399 chloride, 396 Diethylene diamine, 314, 358 disulphide, 305 sulphine ethyl iodide, 305 disulphone, 305 glycol, 295, 298 iniide oxide, 310 oxide, 298 sulphone, 305 tetrasulphide, 305 Diethylin, 476 Diffusion process, 574 Diformin, 475 Diformyl, 320 hydrazine, 228 Diglycerol, 476 Diglycide, 476 Diglycollamic acid, 349 amidic acid, 356, 403 dimide, 355 Diglycollic acid, 339, 349 Diglycollide, 339 Diglycollimide, 349 Diglycolyldiamide, 358 Dihaloid paraffins, 102 propanes, 303 Dihydrazones, 328 Dihydropyridine derivatives, 377 Dihydroxylene, 221 Di-iodo acetic acid, 275, 366 acetone, 217 acetylene, 106 acrylic acid, 282 fumaric acid, 464 Di-iodohydrin, 474 methane disulphonic acid, 393 methyl ether, 202 Di-isethionic acid, 306 Di-iso amylene, 94 butyl glycollic acid, 317, 338 nitroso acetone, 479 butyric ester, 484 propionic acid, 483 valeric acid, 484 Di-ho-propyl, 85 glycol, 297 ketone, 215 f oxalic acid, 338 valeral glutaric acid, 468 valeryl, 297 Diketo-butane, 322 butyric acid, 484 hexamethylene, 443 piperazines, 358 tetracarboxylic acids, 572 valeric acid, 484 Diketone carboxylic acids, 572 dichlorides, 322 Dilactyl diamide, 358 Dilactylic acid, 339 Dilrevulinic acid, 529 Dilituric acid, 507 Dimalonic acid, 531 Dimethyl (see Ethane) acetal, 200 acetic acid, 247 acetylene, 99 acrylic acid, 284 6oo INDEX. Dimethyl allene, 97 alloxan, 506, 509 allyl caruinol, 131 amido acetone, 319 amine, 167 iodide, 169 angelicalactone, 362 arsine, 177 aticonic acid, 466 aziethane, 328 bishydrazimethylene, 328 butyrolactone, 346, 537 carbinol, 125 conmalic acid, 496 coumalin, 362 cyanuric acid, 420 diacetylene, 99 dichlorsuccinic anhydride, 466 diethyl ammonium iodide, i63 dihydroxyheptamethylene,325 diketone (see Diacetyl). dinitro butyric acid, 378 ethane tetracarboxylic ester, 531 [Dimethyl ethanol], 126 ethyl acetic acid, 249 acetonitrile, 268 carbinol, 127, 129 methane, 85 ethylene oxide, 299 furazane, 328 glutaric acids, 454 glycidic acid, 481 glyoxime, 328 peroxide, 328 hydantoin, 402 hypoxanthine, 516 indol, 381 acetic acid, 381 isocyanuric acid, 420 isopropyl ethylene-lactic acid, 342 isoxazole, 328 itaconic acid, 466 ketazmes, 220, 460 ketol, 317 ketone, 214 laevulinic acid, 381 malonic acid, 381, 442 methylene dithioglycollic acid, 347 nitramine. 171 nitrosamine, 170 [Dimethyl-octanon-acid]. 382 oxalic acid, 338 oxamic acid, 164 oxamide, 163, 435, 436 Dimethyloxetone, 217, 478 oximidornesoxalamide, 498 oxyadipic acid, 527 parabanic acid, 506 piperidine, 169 [Dimethylpropan-acid], 249 propyl methane, 85 pyrazine, 319, 473 pyrene, 479, 521 pyridone, 363 pyrroUdine, 315 racemic acid, 369, 527 succinanil, 449 succinic acid, 445 succinimide, 449 succinyl chloride, 446 thetine, 348 thiosemicarbazide, 410 throurea, 409 urea chloride, 396 valerolactone, 346 xanthine, 514 Dimyricyl, 86, 130 Dinitro-brombenzene, 165 caproic acid, 378 dimethyl aniline, 167 ethylene urea, 400 ethylic acid, 185 glycoluril, 400 paraffins, 154, 204, 212, 219 propane, 155, 248,308, 313 stilbenes, 50 Dioctyl acetic acid, 249 Diolefine alcohols, 132 ketones, 221 Dioxalo succinic acid, 572 Dioxethylamine, 308, 356 Dioximes, 327, 528 Dioximido butyric acid ester. 484 hyperoxid-succinic acid, 528 valeric acid, 483 Dioxobehenic acid, 288 butyric acid, 484 piperazines, 358 stearic acid, 288 succinic acid, 528 valeric acid, 484 Dioxyacetic acid, 363 acetone, 478 behenic acid, 481 benzophenone, 75 butyric acid, 480 dimethyl glutaric acids, 527 ethylene succinic acids, 521 fumaric acid, 525, 528 glutaric acid, 527 isobutyric acid, '480 INDEX. 60 1 Dioxyisoctylic acid, 480 ketone-dicarboxylic acids, 538 malonic acid, 497 olefine dicarboxylic acids, 528 oxosuccinic acid ethyl ester, 528 propane tricarboxylic acid, 538 propionic acid, 480 propylamine, 167 propylmalonic dilactone, 5 2 7 quinone dicarboxylic acid ester, 528 stearic acid, 285, 481 tartaric acid, 401, 485, 525, 527 tricarballylic acid, 538 undecylic acid, 481 valeric acid, 480 Diphenyl bispyrazolon, 528 butyrolactone, 446 oxytriazine, 405 Dipropargyl, 99 Dipropionyl, 297 cyanide, 371, 486 Dipropyl-acetyleneglycol-dibutyrate, 297 carbodi-imide, 426. chloramine, 169 glycollic acid, 317, 338 ketone, 216 nitramine, 171 Dipyrazolon derivatives, 528 Disaccharides, 573 Disacryl, 208 Disodium glycollate, 295 Dissociation, 71, 524 Distillation, fractional, 64 under ordinary pressure, 63 reduced pressure, 63 Disulphone acetone, 218 Disulphonic acids, 204 Dithio-acetal, 204 acetone, 21 8 carbamic acid, 407 carbazinate of diammonium, 410 carbonic acid, 389, 391 ethylene ester, 391 cyanic acid, 422 diamido dilactic acid, 347 diethylamine, 165, 170 dilactylic acid, 347 dimethylamine, 170 ethyl dimethyl methane, 218 glycol. 304 methanes. 407 tetra-alkyldiamines, 170 ethyl diamines, 170 Diurea, 405 Divinyl, 99, 519 Docosane, 86 Dodecane, 86 Dodecylene, 92 Dotriacontane, 86 Double acid amides, cyclic, 357 Dulcitol, 120, 541 Duroquinone, 323 Dynamical isomerism, 463 Dynamite, 474 EARTH oil (petroleum), 87 Ebulliscope, 123 Egg albumin, 583 yellow, 475, 583 Eicosane, 86 Elaidic acid, 50, 286 Elaidin, 475 Elastin, 586 Elayl, 90 chloride, 302 Electricity, action on carbon compounds 76 Electrolysis, 76 Electrosynthesis, 240 Elementary analysis, organic, 18 Elemi re>in, 588 Elution, 574 Empiric formula, 25 Emulsion, 551,573, 587 Energy isomerism, 463 Enol form, 55 Enzymes, 587 Epibromhydrin, 477 chlorhydrin, 340, 477, 482 ethylin, 477 Epihydrin alcohol. 476 carboxylic acid, 481 Epihydrinic acid, 481 Epiiodohydrin, 477 Equivalence of the carbon bonds, 38 Erlenmeyer's rule, 53, 319 Erucic acid. 50, 286, 481 Erythren, 99 Erythrin, 520 Erythrite. 107, 126, 520 Erythritic acid, 521 Erythro dextrine, 578 glucic acid, 521 glucin, 520 Erythrose, 520 Ester formation, reaction velocity, 253 Esters, 133, 136 Ethal. 129 [Ethan acid], 243, 261 [Ethanal], 195 602 INDEX. [Etbanal acid], 316 [Ethanal amine], 364 Ethane, 82 tetracarboxylic acid, 443, 531, 572 tricarboxylic acid, 443, 517, 531 Ethan-diacid], 432 Ethan-dial], 320 Ethan-dinitrile],437 Ethan-diol], 294 Ethan-nitrile], 268 Ethanol], 118 Ethanol nitrile], 350 Ethanoyl chloride], 259 Ethanthiol acid], 347 Ethene], 90 ithenyl amidine, 270 amidoxime, 271 radical, 222 tricarboxylic ester, 517, 539 trichloride, 103 Ether, 134 aceticus, 255 bromatus, 141 compound, 132 mixed, 132 simple, 132 sulphuric acid, 144 [Ethine], 95 Ethionic acid, 307 Ethidene acetoacetic ester, 382 acetone, 221 acetpropionate, 202 bromide, 201 chlorhydrin acetate, 202 chloride, 91, 201, 443 diacetate, 202 diacetic acid, 453 diethyl ester, 200 sulphone, 204 dimalonic ester, 457, 532 dimethyl ether, 200 disul phonic acid, 204 dithioethyl, 204 dithioglycollic acid, 347 diurethane, 395 glycol, 199 iodide, 201 lactic acid, 335, 349 malonic acid, 278, 457, 532 mercaptal, 204 oxide, 195 phenylhydrazine, 207 propionic acid, 278, 284, 493 succinic acid, 441, 466 urea, 400 Ethoxy-chlorbutane, 301 fumaric acid, 495 isocrotonic ethyl ester, 362 male'ic acid, 495 methylene aceto-acetic ester, 483 acetyl acetone, 478 malonic ester, 494 pyridine, 363 Ethoxyl-acetoacetic ester, 482 amine, 172 chloracetoacetic ester, 482, 521 isosuccinic acid, 456, 486 oxalacetic ester, 527 propionic acid, 338 Ethyl acetaldehyde hydrazine, 207 acetoacetic acid, 328 acetoglutaric acid, 502 acetylbutyric acid, 382 acetylene, 97, 98 carboxylic acid, 288 alcohol, 82, 118, 134, 243 aldehyde (see Acetaldehyde). amidovaleric acid, 359 amine, 118, 167 benzhydroxime-acetic acid, 350 boric acid, 1 80 bromide, 141 butyrolactone, 346 caprolactone, 346 carbamic ester, 394 carbonic acid, 386 carbylamine, 237 chlor-ether, 301 chloride, 83, 119, 141 chlormalonic ester, 486 cyanamide, 426 cyanide, 268 diacetamide, 265 diacetoacetic ester, 484 dichloramine, 169 di-sulphide, 150, 261 -ethane tetracarboxylic acid, 531 ether, 134 ethylene, 94 formamide, 227 fumaric acid, 379, 465 glutaric acid, 453 glycidic ether, 477 glycol acetal, 316 glycollic acid, 338, 366, 527 hydantom, 402 hydrazine, 171 sulphuric acid, 171 hydride, 82 hydroxylamine, 172 hypochlorite, 147 imido chlorcarbonic acid ester, 404 INDEX. 603 Ethyl imido pyruvyl chloride, 371 iodide, 142 isocyanide, 237 ketol, 317 Irevulinic acid, 380 mercaptan, 149, 406 mercuric hydroxide, 186 methyl acetylene, 98 ether, 136 glyceric acid, 280 valerolactone, 346 methylene amine, 205 nitramine, 171 nitrate, 124, 143 nitrite, 144 nitrolic acid, 158 oxalic acid. 434 chloride, 434 oxybutyric acid, 342 piperidone, 360 propylacetic acid. 249 succinaldehyde-dioxime, 327 succinimide, 448 sulphide, 149 sulphite, 147 sulphoacetic acid, 348 sulphocarbamic ethyl ester, 406 sulphone, 151 sulphonic acid, 153 sulphopropionic acid, 348 sulphoxide, 151 sulphurane, 305 sulphuric acid, 119, 124, 133, 145 tetronic acid, 379 thiocarbonic acid, 391 thionamic acid, 170 sulphonic ester, 153 urea, 399 chloride, 396 valerolactam, 360 valerolactone, 346 Ethylene, 76, go bromide, 91, 302, 532 chlorhydrin, 118, 293, 300 chloride, 91, 302 cyanhydrin, 350 cyanide, 449 diamine, 312, 395 diethylsulphide, 304 sulphone, 305 dimalonic ester, 532 dimethylsulphide, 304 dinitramine, 312 disulphinic acid, 306 disulphonic acid, 307 ethenylamidine, 312 ethidene ether, 298 Ethylene, glycol, 107, 294 haloids, 302 hydrinsulphonic acid, 306 iodide, 302 lactic acid, 341 mercaptan, 304 methylene ether, 298 oxide, 298 pseudo urea, 404 succinic acid, 443 sulpho urea, 409 tetracarboxylic ester, 533 thiohydrate, 304 urea, 400 urethane, 395 Ethylin, 476 Euglena viridis, 578 Euxanthic acid, 568 Evonymus europasus, 475 FATS, 252, 454, 475 Fatty acids, 239 synthesis decomposition, 251 bodies, 78 Fehling's solution, 545 Fellinic acid, 587 Ferments, 587 Fermentation, 122, 473, 547 amyl alcohol, 127 butyl alcohol, 126 lactic acid, 335 Ferricyanide of potassium, 232 Ferrocyanide of potassium, 232 Fibrins, 583 Fibrin-ferments, 583 globulin. 583 Fibrinogen, 583 Filter paper, Swedish, 579 Fish blubber, 87, 285 Flesh-pieces, 355, 413 (meat) extract, 337, 339, 413 Fluor-alkyls, 139 chlorbromoform, 235 chloroform, 235 Formal, 200 Formalazine, 207 Formal do xi me, 206 glycerol, 476 Formalin, 193 Formamide, 227 Formamidine, 232 Formates, 226 Formazyl carboxylic acid, 233 604 INDEX. Formazyl hydride, 233 Formic acid, 225 aldehyde, 118, 193, 417, 476, 528,530 Formimido ether, 232, 269 Formine, 226, 475 P'ormoguanamine, 412 Formonitrile, 228 Formose, 552 Formoxime, 206 Formula, determination of molecular, 25 empiric, constitutional, ration- al, structural, rearrangement, 337 Formyl (radical"), 224 acetic acid, 364 acetone, 319, 321 chloridoxime, 233, 499 hydrazine, 228 hydroxamic acid, 233 ketone, 321 succinic ester, 495 thiosemicarbazide,'4io tricatboxylic acid, 517 trisulphbnic acid, 235, 387 urea, 400 Freezing-point depression, 32 Fructose, 193, 208, 551, 575 carboxylic acid, 568 Fruit essences, 256 sugar, 551, 553 Fuchsine sulphurous acid (reagent for aldehydes), 545 Fucose, 536 Fulminate of mercury, 238 of silver, 238 Fulminic acid, 237 Fulminuric acid, 238, 585 Fumaric acid, 50, 76, 96, 458, 501, 517, 532 Furazan carboxylic acid, 483, 528 dicarboxylic acid, 498 propionic acid, 483 ring, 3 2 .7 Furfur acrylic acid, 503 Furfural laevulinic acid, 529 Furfurane carboxylic acids, 570 Furodiazoles, 327 Furonic acid, 455 Fusel oil, 122 GALACTAN, 551 Galactite, 551 Galactonic acid, 346, 567 Galactose, 551, 575, 576 Galactose carboxylic acid, 346, 568, 569 [Gala-heptanpentol diacid], 571 Galaheptite, 542 Galaheptonic acid, 553, 568 Galaheptose, 553 Galaoctonic acid, 553, 568 Gallesine, 549 Gasbaroscope, 22 Gaultheria procumbens, 117 Gelatine liquid, 585 tissues, 585 Geneva names, 57 Geranial, 209 Geranic acid, 289 Geraniol, 132, 380 Geranium ethide, 181 Globulins, 357, 583 Glucase, 576 Glucoheptite, 542 Glucoheptonic acid, 568 Glucoheptose, 553 Gluconic acid, 346, 567 Glucononite, 542 Glucononose, 542, 553 Gluco-octite, 542 octose, 553 Glucosamine, 549, 550, 586 Glucosanes, 577 Glucosazone, 549 Glucose, 120, 534, 543, 548, 553 amido-guan dine, 550 carboxylic acid, 568 mercaptal, 550 Glucosides, 544, 548, 549 Glucosone, 549 Glucuronic acid, 568, 585 Glutaconic acid, 452, 467, 494, 496, 533, 538 Glutamine, 69. 493 Glutaminic acid, 493, 581 Glutaric acid, 452, 538 Glutarimide, 349, 453 Glutazine, 496 Glutin, 585 peptones, 586 Glutinic acid, 468 Glyceric acid, 247, 340, 480, 481 Glycerides, 475 Glycerol, 107, 130, 226, 471, 476, 497, 573 aldehyde, 477 ether, 476 ketone, 477 phosphoric acid, 475 sulphuric acid, 475 Glycerose, 477, 534, 552 INDEX. 6o 5 Glyceryl chloride, 475 Glycide, 476 acetate, 477 Glycidic acid, 340, 481 Glycin (see Glycocoll). anhydride, 355, 358 Glycocholic acid, 355, 587 Glycocoll, 230, 354, 401, 510, 587 amide, 355 Glycocyamine, cyamidine, 412 Glycogen, 576, 578 Glycol, 125, 294, 386,429 acetal, 316 acetate, 304 aldehyde (see Glycolyl alde- hyde). brurahydrin, 301 carbonate, 386 chloracetin, 304 chlorhydrin, 125, 301 dinitrate, 303 ethyl ether, 297 nitrohydrin, 308 Glycollic acid, 124, 244, 274, 334, 364, 429, 472 amide, 349 anhydride, 338, 339 ethyl ester, 339 ester, 338 nitrite, 350 Glycollides, 339 Glycolloglycollic acid, 339 Glycoll-sulphuric acid, 303 urelne. 400 Glycoluric acid, 401 Glycoluril, 327, 400, 401 Glycolyl-aldehyde, 125, 199, 295, 315, 53* guanidine, 412 urea, 401 Glycose (see Glucose). Glycosides (see Glucosides). Glycosin, 321 Glyoxal, 124, 199, 295, 320, 400, 429, 528 acid (see Glyoxylic acid), osazone, 328 osotetrazone, 328 Glyoxalines, 321,322,401 G yoxime, 321 Glyoxyl-carboxylic acid, 483 Glyoxylic acid, 124, 199, 224, 274, 295, 364,' 400, 429.47 2 Glyoxyl-isohutyric acid, 483 propionic acid, 381, 483 urea, 504 Granulose, 577 Grape sugar, 548 synthesis, 553 space- isomerism, 560 Green malt, 121 Groups, 39 Guaiacol, 528 Guaicol, 208 Guanazole, 415 GuaneIdes,"4I2 Guanidine, 238, 384, 411 Guanido acetic acid, 412 carbonic acid, 414 dicarbonic acid, 414 propionic acid, 412 Guanimines, 412 Guanine, 514 Guanoline, 414 Guanyl-guanidine, 414 urea, 414 Gulonic acid, 566 Gulose, 551 Gums, 578 H H^MATIN, 585 Hgemato-chromogen, 585 porphyrin, 585 Hsemin, 585 Haemoglobins, 584 Half-ortho-oxalic acid, 434 oxalic ester, 434 , shadow apparatus, 574 Halogenides, 223 Halogen ketoximes, 319 mononitro paraffins, 154 defines, 104, 142 paraffins, 99 Halogens, determination, 23 Heat, action of, upon carbon compounds, 73 of combustion, 72 Hectograph material, 473 Heneicosane, 86 Hentriacontane, 86 Heptachlorethidene acetone, 221 Heptacosane, 86 decane, 86 methylene, 89 [Heptan-diacid], 455 Heptane, 86, 129 [Heptanpental-diacid], 571 [Heptantrion], 479 Heptenyl amidoxime, 271 Heptinic acid, 482 Heptolactones, 346 6o6 INDEX. Heptyl-acetate, 93 alcohol, 129 Heptylic acid, 250 mustard oil, 425 Heracleum giganteum, 243, 247, 256 sphondylium, 129, 243 Hesperidine, 536 Heterocyclic compounds, 78 Heteroxanthine, 514 Hexachlorbenzene, 100 diketo-R-hexene, 463 ethane, 103 Hexacontane, 84 decane, 86 dec>l alcohol, 129 decylene, 257 di-indiol, 297 ethyl melamine, 428 hydrobenzene, 89 mesitylene, 88 pyrazine, 314, 358 xylene, 88 iodobenzene, 1 06 methyl benzene, 98 methylene, 89 bromide, 303 diamine, 313 glycol, 296 tetracarboxylic acid, 532. tetramine, 205 methyl melamine, 428 Hexane, 84, 85, 86 [f lexan-diacid], 454 [Hexandion], 322, 323 [Hexantriol], 473 Hexaoxybenzene potassium, 236 Hexenic acids, 284 Hexenyl amidoxime, 271 Hexinic acid, 482 Hexites, 540, 557 Hexonic acids, 557 Hexoses, 543, 555 Hexyl alcohol, 129 butyrolactone, 346 Hexylene glycols, 296 oxide, 299 Hexyl-erythrol, 99, 520 Hexylic acids, 250 iodide, 140, 540 Hippuric acid, 354> 5 10 Hoffmann's anodyne, 135 Homo-aspartic acid, 491 choline, 309 coninic acid, 359, 360 laevulinic acid, 381 Homologous series, 40 liomopiperidic acid, 359 terpehylic acid, 493 Hyalogens, 584 Hydanto'in, 401, 412 Hydantoic acid, 401, 412 Hydracetamide, 205 Hydracetylacetone, 213, 221, 318 Hydracrylic acid, 295, 341 Hydramines, 308 Hydrazi-acetic acid, 366 propionic acid, 371 Hydrazide acetaldehyde, 316 Hydrazido-mesoxalamide, 498 Hydrazine, 171, 367,415 carbonic ester, 404 ureas, 399 Hydrazino-fatty acids, 361, 365 nitriles, 206 Hydrazo-dicarbonamide, 405 dicarbonamidine, 415 dicarbonic acid, 405 dicarbonimide, 405 dicarbon thio-amide, 410 fatty acids, 361 formamide, 405 thioallylamide, 410 Hydrazones, 207, 220, 328, 367, 371, 546 Hydrazoximes, 328 Hydroaromatic compounds, 77 carbons, 78' halogen derivatives of, 101 chelidonic acid, 503 flavic acid, 437 Hydrogen, addition, 39 determination, 19 pure, 227 Hydrolysis, 120 muconic acids, 467 sorbic acid, 284, 481 Hydroxamic acids, 223, 270 Hydroxy-adipic acid, 494 caffeine, 511, 515 laevulinic acids, 381, 382, 483 amine, 237 Hydroxyl acetic acid, 350 alkyl, 172 group, 40 oxamide, 436 sebacic acid, 494 tetramethyl piperidine, 219 urea, 406 Hydurilic acid, 509 Hypochlorous acid ester, 147 Hypogreic acid, 285 Hypoxanthine, 5*3 INDKX. 607 I IDITE, 541 Idonic acid, 536, 567 Ido saccharic acid, 558, 569 Idose, 541, 551, 567 Ilex paraguayensis, 515 Illuminating gas, 96 Imid azoles, 321 azolones, 319 azolylmercnptans, 319 Imide bases, 167 chlorides, 223, 268 Imides of dicarboxylic acids, 432, 448 of glycols, 314 Imido-acetoacetic acid nitrile, 378 acetonitrile, 356 carbonic acid, 404 dicarbonic acid, 403 ethyl succinic acid, 526 malonamide, 440 oxal ether, 438 pseudo uric acid, 506, 507, 516 pyroracemic acid, 371 thio-carbonic acid, 406 thiourazole, 411 Indol, 581 Inulin, 578 Inversion, 120, 573 Invertin, I2O, 573, 587 Invert sugar, 120, 552, 573 Iodine determination, 23 solubility, 390 reaction with starch, 577 lodo-acetaldehyde, 199 acetone, 217, 317 acetoxime, 319 acetylene, 106, 288 acrylic acid, 281 alkyls, 101, 142 cyanogen (see Cyanogen iodide), ethane, IOI, 124, 142 ethylamine, 311 fatty acids, 272 lodoform, 102, 124, 159, 215, 224, 235, 386 reaction, 123 fumaric acid, 463 lodohydrin, 124 lactic acid, 340 methyl ether, 134, 202 propiolic acid, 288 propionic acid, 275, 341, 454, 502 stearic acid, 286 Iris root, 250 Isatine, 55 Isethionic acid, 30^, 306 Iso-acetonitrile, 237 Isoamylamine, 167 amylene, 93, 94, 129 glycol, 296 isonitrosocyanide, 320 nitrosate, 320 amyl ether, 136 amylidene acetone, 221 asparagine, 491 barbituric acid, 513 butane tricarboxylic acid, 517 butenyl tricarboxylic acid, 453 butyl acetaldehyde, 196 acetic acid, 249, 265, 268 alcohol, 126 amine, 167 butyrolactone, 346 carbinol, 122, 127 butylene, 89, 92, 94, 127 glycol, 296, 301 oxide, 299 haloids, 140 propyl-ethyl-methyl ammonium chloride, 169 butyraldehyde, 196, 206 butyronoxime, 220 butyric acid, 126, 247, 256, 259, 261 butyryl cyanide. 371 caprolactone, 284, 346, 494 cholesterine, 588 choline, 309 citric acid, 530 crotonic acid, 50, 282 cyanate of potassium, 230, 417 cyanic acid, 416 ester, 162, 398, 417, 423 tetrabromide, 415 cyanides (see Isonitriles). cyanogen oxide = z'-cyanogen oxide, 415 tetrabromide, 415 cyanuric esters, 420 cyanurimide, 427 cyclic compounds, 77 dehydracetic acid, 376, 496 dialuric acid, 513 dibutylene, 92, 94 dulcite, 536 erucic acid, 286 glucosamine, 549, 552 heptenic acid, 284 heptylenic acid, 346, 493 hydrosorbic acid, 284 Isologous series, 40 malic acid, 486 maltose, 576 melamine, 427 Isomerism, chemical, 41 6o8 INDEX. Isomerism, dynamical, 462 physical, 44 Isomuscarine, 316 nitramine acetoacetic ester, 483 fatty acids, 360 nitrile reaction, 166, 235 nitriles, 54, 225, 236 nitropropane, 157 Isonitroso acetic ester, 528 acetoacetic e.-ter, 484, 528 acetylacetone,479 barbituric acid, 509 glu'aric ester, 502 ketones, 212, 213, 325, 376 Isevulinic acid, 484 malonic ester, 498 propionic acid, 371 Isooleic acid, 286 Isophoronr, 214, 221 propenyl ether, 136 propyl acetylene carboxylic acid, 288 acetyl valeric acid, 382 alcohol, 122, 125, 472 amine. 167 Isopropylbutyrolactone, 346 carbinol, 126 propylene malonic acid, 457 ether, 136 glutolactonic acid, 494 haloids, 125, 140 [Isopropylheptanon-acid], 382 Isoprouylmalic acid, 492 tricarballylic acid, 518 pyrotritartaric acid, 324 quinoline, 74, 78 rhamnonic acid, 537 rhamnose, 536 saccharic acid, 571 saccharin, 537. 576 succinic acid, 246, 441 thio-acetanilide, 262 cyanic acid, 55, 421 ester, 162, 423 cyanuric ester, 425 trichlorglyceric acid, 370 triethylin, 316 Isouretine or isuret, 233 uric acid 509 valero-glutaric acid, 467 valeric acid, 248, 259 aldehyde, 75, 196, 206, 357 Isoxazoles, 319, 327 Isoxazolon hydroxamic acid, 5 Itabrompyrotartaric acid. 451, 492 Itaconic acid, 76, 465, 492 anhydride, 53, 465 ester, 465 Itachlorpyrotartaric acid, 451, 492 Itaconilic acid, 465 Itamalic acid, 492 K KETAZINES, 220, 546 Ketines, 319 Ketipic acid, 528 Ketoamines, 320 brassidic acid, 288 butyric acid, 372 glutaric acid, 501 hexoses, 551 malonic acid group, 497 succinic acid group, 499 Ketols, 317 Ketone-alcohols, 317 chlorides, 213 carboxylic acids : mono-, 368,497, 531, 539 di-, 484, 527 tri-, 521, 538 decomposition of acetoacetic ester, 375 of oxalacetic ester, 499 halides, 102 phenylhydrazones. 220 Ketones : mono-, 209 ; di-, 323 ; tri-, 479 ; tetra-, 521 Ketonic acid nitriles, 268, 370, 378 oximes, 371 Ketooxystearic acid, 286 pentacarboxylic ester, 454 pentamethylene, 454 piperidine, 360 stearic acid, 288, 382, 383 substitution products, 211 succinic acid group, 499 Ketoxime carboxylic acid, 241 Ketoximes, 158, 219 Kopfer's method, 21 LACTAMS, 52, 358 Lactam forms, 55 Lactamide, 349 Lactarius volemus, 542 Lactates, 336 Lactazams, 363 Lactic acids, 336, 337 ethidene ester, 341 fermentation, 335 INDEX. 609 Lactic acid nitrile, 349 Lactides, 339 Lactime form, 55 Lactimide, 358 Lactobionic acid, 575 biose, 575 Lactones, 52, 342 Lactonic acid, 567 acids, 486, 492, 494, 530 Lactose, 575 carboxylic acid, 576 Lacturic acid, 402 Lactyl urea. 402 Lactylo-lactic acid, 339 Loevulinic acid, 379 Lasvulose, 379, 551, 568 l.anoceric acid, 588 Lanoline, 588 palminic acid, 588 Laurie acid, 216, 249, 250, 265, 268, 271 aldehyde, 196 Laurone. 215, 220 Laurus nobilis, 250 Lead alkyls, 187 ethide, 187 plaster, 253 sugar of, 245 vinegar, 246 white, 246 Leather, 585 Lecithin, 309. 475 Leinoleic acid, 286 Leiocome, 578 Lepargylic acid, 455 Leucelnes, 581 Leucic acid, 337 Leucine, 47, 69. 357, 581, 586 Leucoturic acid, 59 Lichenine, 578 Liebig's potash bulbs, 19 Light, action of, upon carbon compounds, 74 Lignose, 579 Ligroine, 87 Limit alcohols, 109 hydrocarbons, 79 Linalool, 132, 380 Linking of the carbon atoms, 37 Linseed oil, 286 Loevo asparagine, 490 aspartic acid, 490 glyceric acid. 480 lactic acid 336 mandelic acid, 69 malic acid, 487 tartaric acid, 69, 526 Lubricating oil, 88 Lupeol, 588 Lupeose, 576 Lutidine carboxylic ester, 483 Lycine, 310 Lycium barbarum, 310 Lysatin, 581 Lysatinin, 581 Lysidine, 312 Lysine, 581 Lyxonic acid, 536, 537 Lyxose, 536 M MAGNESIUM alkyls, 184 Mashing process, 122, 576 Malamic ester, 489 Malamide, 489 Malates, 488 Malein anil, 460 Maleicacid, 50, 96, 459, 460 electrolysis of, 76 Malic acid, 487 Malonic acid, 439, 242, 244, 274, 281, 402, 513 ester, 242, 321, 440, 500, 506 Malonamide, 440 amic ester, 440 diacetic acid, 532 diamidoxime, 440 dihydroxamic acid, 440 ethylene ester acid chloride, 440 ethyl ester acid, 77 hydrazide, 440 Malononitrile, 440 tricarballylic acid, 532 Malonyl guanidine, 56 urea, 506, 513 Malt, 121 sugar, 121, 576 Malto-bionic acid, 576 biose, 576 Maltonic acid, 566 Maltose, 576 carboxylic acid, 576 Mandelic acid, 47, 68 Manna, 540, 570 M mnide, 540 Mannitol, 107, 120, 540 Mannitan, 540 Manno heptite, 542 heptonic acid, 567 heptose, 553, 567 nononic acid, 553, 567 nonose, 553 6io INDEX. Manno-octite, 542 octonic acid, 567 octose, 553 saccharic acid, 569 Mannose, 547 carboxylic acid, 567 Margaric acid, 216, 250 Margarine, 252 Marsh gas, 80 Meconic acid, 496 Melam, 428 Melamine, 427 Melanurenic acid, 427 Melecitose, 577 Melem, 428 Melibiose, 576 Melissic acid, 249, 251 Melissyl alcohol, 129 Melitose, 577 Melitriose, 577 Mellon, 428 Melting point, regularity, 62 Mendius' reaction, 162 Menthone, 382 Mercaptal carboxylic acids, 347 Mercaptals, 204, 534 Mercaptan carboxylic acids, 347 Mercaptans, mercaptides, 148 Mercaptol carboxylic acids, 347 Mercaptols, 212, 218 Mercaptothiazoles, 407 Mercurialis perennis and annua, 1 66 Mercury acetamide, 264 alkyls, 83, 86 allyl iodide, 186 cyanide, 231, 420 ethide, 186 Merotropy, 54 Mesachlorpyrotartaric acid, 45 1 Mesaconic acid, 379, 464 dibrompyrotartaric acid, 452 Mesitene lactam, 362, 363 lactone, 362 Mesitonic acid, 381, 494 Mesitylene, 98, 214 Mesityl-oxide, 214, 217, 219, 221, 381 oxalic acid, 485 Mesitylic acid, 494 Mesodinitroparaffins, 158, 219 propane, 159 Meso-form, 445 tartaric acid, 48, 51, 69, 522, 523 Mesoxalic acid, 402, 473, 497, 504 Mesoxalyl urea, 508 Mesoxanilidimide chloride, 499 Metacrolein, 208 formaldehyde, 194 Metacarbonic acid, 385 Metaldehyde, 195 Metallo-organic compounds, 182 Metamerism, 41 Meta-propylaldehyde, 197 saccharic acid, 346 saccharin, 537, 538 Methacrylic acid, 283, 453 Methane, 76, 80, 246 derivatives, 76 [Methanal], 193 [Methanol], 117 Methenyl tricarboxylic acid, 517 Methazonic acid, 156 Methenyl (radical), 222 amidine, 232 amidoxime, 233, 271, 396 bisacetoacetic ester, 483, 529 bismalonic ester, 533 carbohydrazide, 405 Methine (radical), 222 trisulphuric acid, 204, 235 Methionic acid, 204 [Metho^'-ethyl^-heptane], 80 Methose, 552 Methoxyisocrotonic acid, 362 Methoxylamine, 172 dimethyl acetoacetic ester, 482 Methyl acetoacetic acid, 328, 372, 378 pyronon, 5 21 succinic acid, 501 acetylene, 98 carboxylic acid, 288 acetyl urea, 400 adipic acid, 455 alcohol, 117 aldehyde, 193 alloxan, 508 allyl ketones, 216 ketoximes, 220 nitroamine, 171 propyl-carbinol, 342 amine, 166. arabinoside, 536 bromide, 141 brommalonic ester, 442 Methyl butanal], 196 Methyl butanon], 216 Methyl butan acid], 248 3-Methyl-i-butine], 98 Methyl butyl acetic acid, 249, 568 amine, 167 nitramine, 171 tetrazine, 172 butyrolactone. 345 carboxylic acid, 486 INDEX. 6l Methyl carbamic ester, 394 carbimide, 418 carbonic acid, 386 carbylamine, 237 chloramylamine, 311 chloride, 141, 164 chloroform, 103 crotonic acid, 283 cyanamide, 426 cyanide, 268 diacetamide, 265 diethyl acetic acid, 249 methane, 85 dihydro furfurane, 300 pyrrol, 318 di-iodoamine, 169 dimethyl phenyl pyridozolon, 381 dioxytriazine, 395 disulphide, 150 ether, 134 ethyl acetaldehyde, 196 acetic acid, 246, 248 acetonitrile, 268 acetylene, 98 acroleln, 209 amine, 167 carbincarbinol, 122, 127 carbinol, 126 diketone, 322 ethylene, 94 glycollic acid, 338 glycollo-nitrile, 350 glyoxime, 327 peroxide, 327 ketone, 216 diethyl sulphone, 218 nitramine, 171 oxyacetic acid, 283 oxybutyric acid, 342 pinacone, 216 propyl isobutyl ammonium chloride, 52 formyl acetic ester, 362 fumaric acid, 464 furfurol, 536 glucoside, 550 glutaric acid, 453 glutolactonic acid, 380, 494 glyceric acid, 480 glycidic acids, 481 glycocoll, 355 glycocyamidine, 413 amine. 413 glyoxal, 321, 328 glyoxalidine, 312 osazone, 328 Me:hyl glyoxalosotetrazone, 328 glyoxime, 327 guanidine, 412, 413 acetic acid, 413 [Methyl-heptanoltrion], 520 [Methylheptanon], 221 Methyl-d-hexene, 325 hexylacetonitrile, 268 hydantoin, 401, 402, 413 hydrazine, 171 hydroxylamine, 172 hypochlorite, 147 imidothiodiazoline, 410 indol, 581 iodide, 142 isobutylbutyrol acton e, 346 isobutylenamine, 205 glyoxime, 327 citric acid, 530 cyanate, 418 cyanide, 237 propylacetamide, 265 carbinol, 127, 128 ketoxime, 220, 320 isoxazole, 327 isoxazolon, 376 ketol, 317 laevulinaldoxime, 321 Isevulinic acid. 380 malic acid, 492 ester acid, 376 mannoside, 548 mercaptan, 149 mercury nitrate, 186 methane (see Ethane), methylene amine, 205 nitramine, 170 nitrate, 143 nitrite, 144 nitrolic acid, 158 nitrourethane, 395 nonylketone, 216 oenanthone, 216 oxalacetic ester, 492, 500 oximidoethyl ketone, 484 oxybutyric acid, 342 glutaric acid, 380, 494 thiazole, 423 valeric acid, 342 parabanic acid, 505 paraconic acid, 278, 346, 492 penthiophene, 453 phenyl pyridazolon, 381 piperidine, 360 [Methylpropanal], 196 [Methylpropan diacid], 441 [Methyl-3-propanol acid], 337 6l2 INDEX. [Methylpropan acid], 249 propionyl acetic acid, 378 propyl acetaldehyde, 196 acetic acid, 249, 266 allyl carbinol, 131 amine, 167 carbinol, 68, 127, 128 ethyl-ethylene glycol, 297 ethylene lactic acid, 342 glyoxime, 327 nitramine, 171 oxybutyric acid, 342 pseudouric acid, 507 pyrazole, 328 pyridazinone, 381 azolon, 381 pyrrolidine, 381 pyrrolidon, 360 quinoline, 316 succinic acid, 444 succinimide, 448 sulphide, 149 sulphite, 146 sulphobromide, 151 chloride, 152 sulphone, 151 sulphonic acid, 152 sulphoxide, 151 sulphuric acid, 145 tetronic acid, 378 tetrose, 520, 536, 563 theobromine, 514 thialdin, 204 thiosemicarbazide, 410 triacetoamine, 219 carballylic acid, 518 carbimide, 420 uracil, 376, 513 uramils, 507 urea, 399 chloride, 396 urethane, 394 uric acids, 505, 512 valerolactam, 360 valerolactone, 346 Methylal, 200 Methylene amido acetonitrile, 231, 354, 356 bromide, 2OI chloride, 201 cyanide, 440 cyanhydtin, 354 diacetamide, 265 diacetic ester, 202 diethyl ether, 200 sulphone, 204 dimalonic ester, 531 Methylene dimethyl ether, 200 disulphuric acid, 204 glycol, 194 heptylamine, 167 hydrinsulphonic acid, 204 iodide, 201, 235, 532 lactate, 339 malonic ester, 456 mercaptal, 204 succinic acid, 465 succinimide, 449 urea, 400 Methylenitan, 552 Micrococcus aceti, 244 Milk albumin, 583 sugar, 575 Millon's reagent, 582 Mineral wax, 88 Molasses, 122, 574 Molecular formula, atomic, 25 empiric, 27 isomerism, 59 refraction, 66 volume, 60 weight, determination of, 26 Monacetin, 475 Monethylin, 476 Monobromacetone, 217 ethyl ether, 202 methyl ether, 202 chlor-ether, 135 ethyl ether, 202 formin, 226, 475 hydrazones, 328 chlorhydrin, 474 methyl ether, 202 methyl sulphonic acid, 393 Monoiodo-methyl ether, 202 Monoses, 543 Monothio-diethylamine, 165 ethylene glycol, 304 Moss, Iceland, 458 starch, 578 Moringa ole'ifera, 251 Morphine, 166 Morpholine, 310 Morphotrophy, 59 Mucedin, 583 Mucin, 584 Mucinogen, 584 Muco-bromic acid, 287, 365, 465, 477 chloric acid, 365 Mucolds, 584 lactonic acid, 495 Muconic acid, 467 Muco-oxy-bromic acid, 483 chloric acid, 483 INDEX. Murexan, 507 Murexide, 510 Muscarine, 309 Muscle juice, 413 Mustard oil, 425 acetic acid, 410, 424 test, 425 seeds, 425 Mycoderma aceti, 244 Mycose, 576 Mycosin, 586 Myricin, 257 Myricyl alcohol, 129, 130 chloride, 130 iodide, 130 Myristic acid, 216, 250, 265, 588 Myristica moschata, 250 Myristin, 250, 475 aldehyde, 196, 206 araidoxime, 271 glycerol ester, 475 Myristone, 216 Myronic acid, 425 Myrosin, 425, 587 N NAPHTHA, 88 Naphthalene, 74 Naphtenes, 88 Naringin, 536 Neftigil, 88 Neuridine, 313 Neurine, 169, 309 Nitramide, 395 Nitramine fatty acids, 360 Nitramines, 170 Nitric acid ester, 143 Nitrile bases. 167 carboxylic acids, 229 Nitriles, 266 Nitrilo-acetonitrile, 356 malonic acid, 440 oxalic ester, 437 oxalimido-ether, 438 succinic acid, 527 tricarboxylic acid, 403 Nitroacetonyl urea, 402 acetic acid, 350 amido-acetamide, 401 amines, 170 barbituric acid, 507 benzene, 154, 161 bromoform, 387 butane, 157 butyl glycerol, 520 Nitrocarbamic acid, 395 cellulose, 474 chloroform, 157, 387 cyanacetamide, 238 erythrol, 520 fatty acids, 350 ethyl alcohol, 124, 308 urea, 399 form, 159, 235, 387 glycerine, 474 guanidine, 414 Nitrogen, determination, 21 carbon monoxide, 389 carbonic methyl ester, 389 Nitrohydantolin, 401 isobutyl glycol, 477 propyl alcohol, 308 valeric acid, 351 Nitrol acetic acid, 438 Nitroamines, 320 Nitrolactic acid, 339 Nitrolic acids, 157, 223, 270 malonic acid, 486 aldehyde, 477 malonyl urea, 507 mannite, 541 methane, 156, 387 disulphuric acid, 235 methylisoxazolon, 482 nitroso-propane, 158 octane, 154, 157 defines, 154 paraffins, 154, 162 phenol, 477 propionic acid, 350 propylene, 157 prusside of sodium, 232 Nitrosates, 93, 319 Nitrosites, 93, 319 uracil, 513 uracilic acid, 513 urea, 399 urethane, 395 Nitroso-amines, 170 diethylin, 170 methylaniline, 167 methylin, 170 guanidine, 415 methyl urethane, 207, 395 paraldimine, 206 urea, 399 urethane, 395 Nitrous acid ester, 144 Nitrotartaric acid, 485, 526 Nobel's blasting oil, 474 Nomenclature, 57 Nonadecane, 86 614 INDEX. [Nonan-diacid], 455 Nonane, 84, 86 Nonnaphtene, 88 Nonoisosaccharic acid, 571 Nonoses, 545, 553 Nonylenic acid, 193, 278, 284 Nonylic acid, 250, 286 Normal structure, 43, 109 Nuclein, 584 ^ Nucleus isomerism, 41 syntheses, 85 Nut oil, 286 OCTADECANE, 86 [Octadien], 99 [Octan-diacid], 455 Octane, 86 Octanolactam, 360 tesserakaideca-carboxylic ester, 559 Octobromacetyl acetone, 323 Octoic acid, 250 Octo-napthen, 88 Octoses, 543 Octyl alcohols, 129, 286 OEnanthol, 129, 196, 206, 277, 286, 349 CEnanthone, 215 CEnanthyl aldehyde, 196 OZnanthylic acid, 250, 261, 265, 268 Oil-forming gas, 90 of garlic, 130, 150 of the Dutch chemists, 302 sweet (see Glycerol). Oils, fats, drying, 286 non drying, 285, 472 Olefine acetylenes, 99 alcohols, 130 aldehydes, 207 carboxylic acids, 276, 455, 518 glycols, 297 haloids, 300 ketones, 221 Olefines, 89 Oleic acid, 50, 276, 285, 455 Olein, 252, 475 Optical rotatory power, 67 Optically inactive substances, decompo- sition of, 68 Orcinol, 383 Orsellinic erythrol ester, 520 Ortho-acetic acid derivatives, 256, 322, 372 acetone ethyl ether, 217 methyl ether, 217 acids, 217 Ortho-carbonic acid esters, 383, 386 formic acid, 217 ester, 224, 233, 478, 483 glyoxal diethylene ether, 321 oxalic acid, 434 silicic acid esters, 147 thioformic acid esters, 204, 234 Osamines, 535, 546 Osazone acetyl glyoxylic acid, 484 Osazones, 328, 546 Oscillation, 56 Osmotic pressure, 29 Osones, 546 tetrazones, 328 triazones, 328 Oxal acetic acid, 491, 499, 571 aldehyde, 320 amidine, 438 Oxalan, 506 Oxalates, 227, 433 citric acid, 571 diacetic acid, 528 diamidoxime, 438 dihydroxamic acid, 438 di-imide dihydrazide, 438 hydrazide, 436 Oxalic acid, 124, 260, 273, 364, 370, 402, 432 ester, 118, 164, 434, 484 imide, 435 Oxalines, 321 Oxalkyl bases, 308 Isevulinic ester, 528 Oxalo nitrile, 436 succinic acid, 531 Oxaltin, 509 Oxaluric acid, 505 Oxalyl chloride, 434 diacetone, 5 21 guanidine, 56 urea, 505 Oxamethane, 435 Oxamic acid, 435 Oxamide, 435 Oxamidine, 271 Oxamine chloride acid ester, 435 Oxanilide dioxime, 238 Oxazolon hydroxamic acid, 498 Oxazomalonic acid, 499 Oxethyl aceto-acetic ester, 345 amine, 124, 309, 356 ethylene sulphide, 304 sulphone methylene sulphonic acid lactone, 305 sulphuric acid, 306 trimethyl ammonium hydroxide, 39 INDEX. Oxetones, 217, 478 Oximes, 161, 206, 219, 320, 325, 367, 371, 376, 382, 500, 535, etc. Oximide chloride acid ester, 435 Oximido-acetic acid, 367 acetone dicarboxylic acid, 502 acetonitrile acetate, 367 butyric acid, 371, 376 cyanpyroracemic acid, 5 dibrompyroracemic acid, 371 ether, 438 glutaric acid, 501 malonic acid, 486 mesoxalyl urea, 509, 513 methyl isoxazolon, 484 propionic acid, 367, 371, 491, 500 succinic acids, 491, 50x5 Oxo-glutaric ester, 501 malonic ester, 498 Oxonic acid, 505, 512 Oxopentamethylene, 454 piperidine, 360 propane, 211 stearic acid, 382 succinic acid, 499 valeric acid, 379 Oxy acetic acid, 321, 330, 334 acetone. 317 acid nitriles, 214, 349 acrylic acid, 362, 369 aldehyde ketones, 478 aldehydes, 315, 477, 521, 535, 542 aldehydo-carboxylic acids, 568 amido-glutaminic acid ester, 502 butyric acids, 337, 342 aldehyde, 193, 316 caproic acid, 342 caprolactone, 381, 481 caprylic acid, 342, 349, 350 carboxylic acids : dioxy-, 479, 521 monoxy-, 329, 485, 529 polyoxy-, 564 tetraoxy-, 537 trioxy-, 521, 538 Oxycitraconic acid, 527 citric acid, 539 coumarine carboxylic acid, 500 crotonic acid derivatives, 362 dialkyl acetic acids, 337 dimethyl nicotinic acid, 496 ethylene succinic acid, 487 formaldehyde, 224 furazan-acetic acid, 500 carboxylic acid, 499, 500 glutaric acid, 493, 494 Oxyhaemoglobins, 584. i obutyl acetic acid, 337 butyric acids, 283, 337, 342, 350, 402 caproic acid, 342 caprolactone, 284, 481 crotonic acid, 362 Oxy-isoctylic acid, 342 heptolactone, 4J heptylic acid, 342 lactone, 481 succinic acids, 370, 486 valeric acid, 284, 337, 350 Oxyisoxazole dicarboxylic ester, 502 Oxyketone carboxylic acids, 482, 521, 5 2 7,57I ketones, 317, 478, 521, 551 lactones, 481 malonic acid, 485 methane disulphonic acid, 235 methylene acetic acid, 361, 364 acetoacetic ester, 483 acetone, 319 acetyl acetone, 478 succinic ester, 49^, 502 diethyl ketone, 319 disulphonic acid, 204 glutaconic acid, 496 malonic ester, 494, 533 propionic acid, 362 furfurol, 552 *"*) pyromucic acid, 235 sulphonic acid, 204 myristic acid, 338 , neurine, 310 nicotinic acid, 496 palmitic acid, 338 pentinic acid. 379 phenyl amidopropionic acid, 581 propionic acid, 581 propionic acid, 335 propyl malonic acid, 345 pyroracemic acid, 482 aldehyde, 478 tartaric acid, 491 quinaldine, 363 stearic acid, 338 su'phonic acids, 204 tetralidine, 208, 316 tetrinic acid, 379, 464 toluic acid, 484 tricarballylic acid, 529 methylglutolactonic acid, 494 uracil, 5 r 3 urethane, 405 uvitic acid. 235, 376, 483 valeric acids, 338, 342 6i6 INDEX. Oxyvalerol acton e, 481 vegetable gums, 579 Ozokerite, 88 PALM fat, 252 oil, 250 Palmitic acid, 92, 130, 215, 250, 286 aldehyde, 196 cetyl ester, 257 myricyl ester, 257 Palmitin, 252 amidoxime, 271 Palmitone, 215, 252 nitrile, 268 oxime, 220 Pancreas, 516, 576 diastase, 573 Pangium edule, 228 Papain, 587 Paper, 579 Parabanic acid, 505 Parachforalose, 550 Paraconic acid, 492 Paracyanogen, 437 Paraffin, 88 alcohols, 117 aldehydes, 189 carboxylic acids, 224, 428, 516, 53L 539 ketones, 209 Paraffins, 79, 93, 138 Paraform, 445 aldehyde, 194 Paralactic acid, 337 Paraldehyde, 195, 282, 477 Paraldinim, 206 Paraldol, 316 Param, 414 Paramucic acid, 570 Param ylum, 578 Paranthracene, 75 propyl aldehyde, 197 sorbic acid, 289, 362 tartaric acid. 523 xanthine, 514 Parchment, vegetable, 579 Pastinica sativa, 248, 256 Paullinia sorbilis, 515 Pectine substances, 579 Pectinose, 536 Pelargonamide, 265 Pelargonic acid, 250, 284 Pelargonium roseum, 250 Penicillium glaucum, 68, 336, 357, 493 Penta-acetyl-glucono-nitrile, 535, 5 50,566 Pentachloracetone, 217 ethane, 103 glutaric acid, 453 pyridine, 467 pyrrol, 448, 463 decane, 86 decatoic acid, 249 [Pentadien], 99 Pentaethyl phloroglucin, 216 erythrite, 194, 520 glycol, 296 Pental, 94 Pentallyldimethylamine, 169 methylene, 89 bromide, 303, 455 derivatives, 78 diamine, 293, 296,313, 3 6 0' 453 glycol, 296 imide, 296, 360, 452 oxide, 299, 360 tetramine, 205 methyl phloroglucin, 216 [Pentan-al], 196 [Pentan-diacid], 452 [Pentan-dion], 322 Pentane, 85, 138 tetracarboxylic ester, 532 tricarboxylic acid, 518 Pentanolid, 345 [Pentanon], 216 [Pentanon-acid], 379 Pentantrion, 479 Pentaoxycaproic acids, 564 pimelic acid, 571 triacontane, 86 Pentenic acids, 283 [Pentine], 98 Pentinic acid, 379, 482 Pentites, 533 space- isomerism of, 556 Pentosanes, 577 Pentylene glycol, 296 oxide, 296, 299 ethylene, 93 Pepsin, 583,5 8 7 Peptones, 584 Perbrom- acetone, 217 ethane, 104 ethylene, 104 Perchloracetaldehyde, 275 acetic methyl ester, 275 acetyl acrylic acid, 383, 463 benzene, 100 butdien carboxylic acid, 288 butine carboxylic acid, 288 INDEX. 6, 7 Perchlorcarbonic ethyl ester, 388 ethane, 100, 103 ether, 135, 136 ethylene, 105, 275 Perchloric ester, 147 methane, 100, 387 methyl ether, 134 mercaptan, 393 sulphthiocarbonic methyl ester, 393 vinyl ether, 136 iodoethylene, 105 Perkin's reaction, 193 Peroxid di-isonitroso butyric acid, 484 Perseit, 542 sulphocyanic acid, 422 Petroleum, 87 benzine, 87 ether, 87 Phasotropy, 54> 5^ Phenanthraquinone, 75 Phenanthrene, 74 Phenol, 488, 568, 581 carboxylic acid, 387 Phenyl-acetic acid, 581 acetol, 317 alanine, 581 amido-dimethyl pyrrol, 328 amidopropionic acid, 581 asparagine-aml, 460, 490 aspartic acid. 490 azoimide, 458 butidone carboxylic acid, 363 butyrolactam, 360 Phenylene-diamine, 322 glycol-acetal, 316 hydrazidomesoxalic acid, 498 hydrazine, 171 glyoxylic ester, 539 laevulinic acid, 359, 38l Phenyl-hydrazino-acetic acid, 361 Phenyl-hydrazoline, 208 Phenyl-hydrazone-glyoxylic acid, 367 mesitonic acid, 381 pyror.icemic acid, 371 Phenyl-hydrazones, 161 Phenyl-ortho-piperazone, 449 succinimide, 449 triazole tricarboxylic acid, 468 Phloroglucin, 217, 536 Phorone, 214, 216, 221, 503 Phoronic acid, 503 Phosgene, 234, 244, 377, 386, 388, 389 Phosphines, 173 Phosphinic acids, 173 Phospho acids, 175 Phosphoric acid esters, 147 Phosphorous acid esters, 147 Phosphorus alkyl compounds, 173 determination, 23 Phthalimide potassium, 162 Phthalyl-amidobutyro-nitrile, 359 glycocoll ether, 354 propyl malonic ester, 359 Phycite, 520 Phyllocyanine, 585 porphyrin, 585 Physical isomerides, 41 properties of the carbon com- pounds, 58 Phytosterin, 588 Picoline, 208, 473 dicarboxylic acid, 371 Picric acid, 387 Picryl chloride, 165 Pimelic acid, 444, 455 Pimelimide, 449 Pinacoline, 209, 216, 296, 370 Pinacolyl alcohol, 129 sulpho-urea, 409 Pinacone, 209, 212, 296 Pinus larix, 577 Piperazine, 314, 358 salt of uric acid, 511 Piperic acid, 525 Piperidic acid, 359 Piperidine, 99, 315, 317, 360, 414, 453 Piperidone, 360 Piperidyl-methane, 359 Piperylene, 99 Pivalic acid (see Trimethyl acetic acid). Place isomerism, 41 Plane-symmetric configuration, 49 Plasmolytic method, 29 Plaster, 252 Plus sugar, 577 Polarization plane, deviation of, 67 Polyethylene-glycols, 295 glycollide, 274, 339 Polymerism, 41 Polymerization, 93, 194, 416 methylene bromides 303 saccharides, 120, 577 Potassium alkyls, 184 cyanide, 230 isocyanate, 417 Potato-spirit, 122 starch, 123 Powder, smokeless, 474. 580 'Prop adieu], 99 "Propanalon], 321 Propan-diacid], 439 "Propandiol], 295 6i8 INDEX. Propandiol-acid], 480 Propandiolal], 477 Propandiol-diacid], 497 [Propandiolon], 477 "[Propane], 84, 85 Propane-tricarboxylic acid], 517 "Propan-nitrile], 368 Tropanol], 125 Propanol acids], 335 Propanol-diacid], 485 Tropanolon], 318 Propanolon acid], 482 Propanon], 214 Propanon-acid], 369 Propanon] -di- and triphenyl hydra- zones, 479 [Propantriol], 471 Propargyl alcohol, 132 amine, 169 ether, 136 haloids, 143 Propargylic acid, 287, 468 E open-acid], 280 openol], 130 penyl-penta carboxylic acid, 539 trichloride, 472 Propeptones, 583 Eopin-acid], 387 opine], 99 piolic acid, 136, 281, 387 Propionaldoxime, 206 Propionamide, 265 Propione, 215 Propionedialkyl sulphones, 218 [Propinol], 132 Propionic acid, 74, 126, 247, 256, 280, 387,473 . Propionon-dicarboxylic acid, 503 Propionyl-carboxylic acid, 370 cyanacetic ester, 499 cyanide, 371 fluoride, 258 formamide, 370 propion aldoxime, 327 propionic ester, 378 Propyl-acetylene, 97, 98 carboxylic acid, 288 alcohol, 122, 125 aldehyde, 126, 196, 209, 211, 214 phenyl-hydrazone, 207 amidovaleric acid, 359, amine, 167 butyrolactone, 346 chloramine, 169 chloramylamine, 311 dichloramine, 169 Propylene, 91, 94, 99, 125, 472 bromide, 303, 444 chlorhydrin, 342 chloride, 142, 303, 472 diamine, 313 glycol, 68, 295 chlorhydrin, 301 diacetate, 304 haloids, 303 oxide, 126, 214, 299 pseudo-thio urea, 410 pseudo-urea, 404 tetracarboxylic acid, 533 Propyl ether, 136 ethylene, 94 halogenides, 140, 141 Propylidene acetic acid, 283 chloride, 201, 301 diacetic acid, 453 mercaptal, 204 mercaptan, 149 methyleneamine, 205 methyl ether, 136 nitramine, 171 nitrolic acid, 158 oxalic acid, 434 paraconic acid, 346, 493 piperidine, 360 pseudonitrol, 158 sulphide, 149 tricarballylic acid, 518 valerolactam, 360 lactone, 346 Protagon, 476 Protein substances, 580 Protocatechuic acid, 528 Protococcus vulgaris, 520 Prussic acid, 228 Pseudo-butylene, 89 forms, 54 ionone, 221 itaconanilic acid, 492 lutidostyril, 362, 363 carboxylic acid, 363 Pseudomerism, 54 nitrols, 157 sulph-hydantoin, 410 sulphocyanogen, 422 urea, 409 thiohydantoin, 410 urea, 404 uric acid, 507, 511, 513 Ptomaines, 310, 311, 581 Ptyalin, 573, 587 Purin, 511 Purpuric acid, 510 Putrescine, 332 INDEX. 619 Pycnometer, 61 Pyra/ine, 314, 316, 319 Pyruzole derivatives, 484, 520 Pyrazoles, 320 Pyrazolin, 208 carboxylic ester, 207, 279, 366 derivatives, 458 Pyrazolon, 367 derivatives, 363, 468, 500, 502, 527, 53' Pyrazolonopyrazolon, 528 Pyridine, 74, 78, 315, 453, 5 2I > 537, 5 6 7 derivatives, 268, 270, 376 Pyridone, 363 Pyrimidine derivatives, 268, 270, 376 Pyrocatechin, 527, 549 Pyrocinchonic anhydride, 466 Pyro-condensaiions, 74 glutaminic acid, 493 mucic acid, 571 Pyrone, 478, 538 derivatives, 538 Pyroracemicacid, 369 alcohol, 317 aldehyde, 321 hydrazone, 328 Pyrosulphuryl chloride, 388 Pyrotartaric acid, 444, 446, 448, 449, 450, 465 terebic acid, 284 tritartaricacid, 324, 370, 485 Pyroxylin, 580 Pyrrol, 300, 315, 449, 586 derivatives, 318, 324, 528, 529 Pyrrolidine, 314 Pyrrol idon, 360 Pyrrol in, 314 Pyrrol ylene, loo Pyruvic acid, 369 Pyruvil, 505 QUARTENYLIC acid, 282 Quercite, 439 Quercitrine, 536 Quick vinegar process, 244 Quinicine, 524 Quinoline, 74. 78, 566, 567 carboxylic acid, 371 Quinones, 322 Quinoxalines, 312, 322, 547 RACEMATES, 524 Racemic acid, 523 Radical theory, 34 Radicals, 17, 34, 39, 22_2 Raffinose, 577 Raoult's law of the depression of the freezing-point, 32 Rape oil, 287 Rapinic acid. 287 Refractometer, 67 Residues, 39 Resins, 390 Resorcinol, 383 Retrogressive substitution, 101, 273, 302 Reversion, 573 Rhamnite, 534 Rhamnohexite, 542 hexonic acid, 564 hexose, 551 Rhamnonic acid, 537 Rhamnose, 530 carboxylic acid, 567 Rhodinol, 132 Rhubarb, 487 Ribonic acid, 537 Ribose, 536 Ricinelaidic acid, 287 Ricinoleic acid, 286 Ricinstearolic acid, 287 Ring-shaped bodies, 78, 195, 218, 268, 270, 298, 314, 324, 326, 328, 334, 338, 353, 358, 360, 366, 400, 413, 419, 446, 448, 454, 456, 483, 496, 532, 539. Roccellic acid, 455 Roeella montaguei, 520 tinctoria, 455 Roman oil of cumin, 283 Rotatory power, magnetic optical, 69 Rum, 122 artificial, 227, 256 Ruta graveolens, 216 S S = Symmetrical. SACCHARATES, 574, 575 Saccharic acid, 537 Saccharimeter, 575 Saccharin, 537 Saccharobioses, 1 21, 572 Saccharomyces cereviske seu viui, uo Saccharon, 538 Saccharonic acid, 538 Saccharotrioses, 577 Saccharum officinarum, 573 Salicin, 543 Salicylic acid, 385, 455 62O INDEX. Salicylide-chloroform, 234 Saliva, 576, 587 Salt of sorrel, 433 Saponification, 137, 239, 252, 255, 264, 472, 517 Sarcine, 516 Sarcosine, 355 anhydride, 358 SchifPs bases, 35P Schizomyces, 122 Schweinfurt green, 246 Sebacic acid, 286, 455 Secalose, 552 Seignette salt, 525 Selenium alkyl derivatives, 154 Semicarbazides, 399, 405 Seminose, 548 Senegal gum, 578 Serecine, 481 Serin, 481 Serum albumin, 583 globulin, 583 Silicon alkyl derivatives, 180 nonane, 180 Silicononyl alcohol, 181 Silicopropionic acid, 181 Silver cyanide, 231 Sinamine, 426 Sinapin, 309 Sincalin, 309 Skatol, 581 acetic acid, 581 carboxylic acid, 581 Sliwowitz, 122 Soaps, 137, 239, 252, 472 Sodium acetoacetic ester, 374. 377, 458 ethylate, 124, 374 formate, Il8 glycollate, 295 malonic ester, 441, 458 press, 374 Sorbic acid, 289 Sorbin oil, 362 Sorbinose, 552 Sorbite, 541, 120 Sorbitol, 120, 54! Sorbose, 552 Sorbus aucuparia, 289 Sorghum saccharatum, 573 Spacial chemistry, 44 Specific gravity, 59 rotary power, 69 Spermaceti, 257 , Sprit, 123 Stachyose, 577 Starch, 1 2 1, 247, 577 gum, 578 Starch, sugar, 548 varieties, 577 Stearic acid, 84, 216, 249, 250, 265, 455 aldehyde, 196 amidoxime, 271 Stearin, 252, 475 candles, 252 Stearolic acid, 288 Stearone, 216 Stearonoxime, 220 Stearoxylic acid, 288, 484 Stereo-chemistry of carbon, 45, 49 of nitrogen, 51 Stibines, 179 Structure, 37 theory, 37, 43 Stuffer's law, 305 Suberene, 89 Suberic acid, 455 Suberone, 455 Succin-aldehyd-dioxime, 327 amic acid, 448 amide, 447, 449 anil, 449 anilic acid, 448 Succinates, 443 Succin-broinimide, 448 ethylamic acid, 448 ethyl ester chloride, 446 haloidimide, 448 hydrazide, 449 Succinic acid, 75, 77, 443, 465 esters, 444, 531 ethylene ester, 444 imide, 448 imidoxime, 450 methylimide, 381 Succino-nitrile, 449 Succino succinic ester, 444 Succinphenyl-hydrazide, 449 Succinyl-chloride, 446 ethylene-diamide, 449 hydroxamic acid, 450 peroxide, 447, 449 Sugar-cane, 573 beet, 573 Sulphamic acids, 170 Sulphamides. 170 Sulphamido-barbituric acid, 509 valeric acid, 359 Sulphinates, cyclic, 347 Sulphine compounds, 150 Sulphinic acids, 153 Sulpho-acetic acid, 306 carbamic acid, 406 carbonic acid, 389, 391 INDEX. 621 Sulpho-cyanacetic acid. 423 cyanacetone, 423 cyanate of potassium, 230, 422 cyan group, 421 hydride, 422 cyanic acid, 422 cyanide of ammonium, 422 of mercury. 422 of potassium, 422 cyanuric acid, 425 diethylamine, 165 Sul phonal, 215, 218 Sulphone-diacetic acid, 348 dipropionic acid, 348 Sulphones, 151, 202, 218 Sulphonic acids, 152 Sulphonium compounds, 150 succinic acid, 489 urea, 407 Sulphoxides, 151 thiocarbonic acid, 389, 391 uranes, 305 Sulphur determination, 23 ether, 134 Sulphuric ester, 144 Sulphurous esters, 146 Sulphuryl-diethylamine, 165 Sulphydrates, 148 Sunlight, action of, 74> 445 Synaptase, 573, 587 Synthesis, 8 1 Synthetic methods, 8l Syntonins, 583, 584 TALITE, 541 Tallow varieties, 250, 475 Talo-mucic acid, 564, 571 Talonic acid, 567 Talose, 551 Tannins, 543 Tar oils, 92 Tartaric acids, 44, 48, 69, 75, 214, 520, 52i, 5 6 3> 570 configuration of, 563 Tartrates, 525 Tartrazine, 528 Tartronic acid, 473, 485, 525 Tai tronyl urea, 56 Taurine, 306, 311 Taurobetalne, 307 carbamic acid, 307, 401 cholic acid, 306, 587 Tautomerism, 54 virtual, 56 Tellurium alkyls, 154 Teraconic acid, 466 Teracrylic acid, 284 Terebic acid, 284, 346, 466, 493 Terpentine oil, 67, 466, 493 Terpenylic acid, 284, 493 Tertiary-butyl alcohol, 126 carbinol, 128 methyl ketone, 1 20, 209, 216 Tetra-acetylene dicarboxylic acid, 468 ethane, 521 alkyl ammonium bases, 168 tetrazones, 172 amide carbon, 384 bromdiacetyl, 322 ethane, 104 formalazine, 415 methane, 102, 384, 387 chlor acetone, 125, 216 diacetyl, 322 diketo-adipic acid, 528 ethane, 103 ethylene, 105 glutaconic acid, 467 methane (see Carbon tetra- chloride). phenyl pyrrol, 449, 464 Tetracosane, 84, 86 decane, 86 ethyl acetone, 215 ammonium compounds, 168 arsonium compounds, 179 ethylium compounds, 168 ethyl-oxalic acid, 434 phosphonium compounds, 174 stibonium compounds, 179 tetrazone, 172 urea, 399 fluor-methane, 102, 383, 386 hydro-carvone, 382 furfurane, 299, 360 naphthalene tetracarboxylic ester, 531 picoline, 318 pyridine, 317 pyrrol. 99, 314, 360 iodo-ethylene, 106 methane, IO2, 383, 387 methyl acetone, 215 alloxantin, 510 ammonium compounds, 1 68 arsonium compounds, 179 diamidobenzophenone, 389 ethylene, 92, 94 glycol, 296 622 INDEX. Tetramethyl ethylene lactic acid, 342 nitrosyl chloride, 308 oxide, 209, 296, 299 sulphocarbamide, 409 glycol, 209 methane, 85 methylene diamine, 205 phosphonium compounds, 175 pyrazine, 381 stibonium compounds, 179 succinic acid, 446 Tetramethylene, 89 bromide, 303 carboxylic acids, 279, 456, 532 derivatives, 78 diamine, 313, 360 glycol, 296, 360 imide, 314, 360 nitrosamine, 315 oxide, 299, 360 methylium compounds, 168 nitromethane, 159. 383, 387 oxyadipic acids, 569 valeric acids. 537 Tetrinic acid, 317, 379, 482 Tetrolic acid, 277, 282, 288 Tetronal, 218 Tetronic acid, 482 Tetrose, 315,520, 534 Thallium alkyl compounds, 186 Theine, 166, 504, 515 Theobroma cacao, 514 bromicacid, 251 bromine, 504, 514 phylline, 504,514, 515 Theory, dualistic, 34 electro-chemical, 34 structural, 37 types, 34, 260, 274 valence, 37 Thermometer, 62 Thetines, 348 Thiacetamide, 269 Thiacetic acid, 261 Thialdin, 203 Thiamides, 223, 269 Thiazoles, 269, 410, 423 Thio-acetaldehyde, 203 acetals, 204 acetic acid, 262, 410 acids. 261 alcohols, 148 Thioaldehydes, 203 benzophenone, 393 carbamic acid, 406 c .rbonic acid, 389, 390 carbonyl chloride, 392 cyanacetic acid, 423 Thiocyanic acid, 422 ester, 391, 423, 426 Thiocyanuric acid, 425 Thiodialkylamines, 170 dibutyric acid, 347 diethylamine, 170 diglycol, 304 diglycollic acid, 347 dilactylic acid, 347 ethers, 149 ethylamine, 311 ethylimide, 232 formaldehyde, 214, 424 glycollic acid, 347 hydantom, 347, 410 ketones, 212 [Thiol acids], 261 Thiolactic acid, 347 Thiomethane, 407 Thion acids, 261 Thionamic acids, 170 carbonic acid, 389, 391 carbon-thiol acids, 391 [Thionthiol acids], 261 Thionuric acid, 509 Thionylamines, 165, 170 Thionylchloride, 165 dialkylamines, 170 diethylamine, 165, 170 hydrazine, 172 ethylamine, 165 tetra-alkyl diamines, 170 Thiophene, 74, 78, 300, 447 carboxylic acid, 571 compounds, 324 phosgene, 390, 392 propionamide, 269 pseudouric acid, 508 semicarbazide, 410 Thio^inamine, 409 Thio sulphuric acids. 153 tetra-alkyl diamines, 1 70 tolene, 380 uramil, 507 urethanes, 407 Tiglic acid, 50, 283 aldehyde, 208 Tin alkyls, 181 Tolane dibromides, 50 dichlorides, 50 Toluene, 73 INDEX. 623 Total reflectometer, 67 Toxalbumins, 581 Toxines, 581 Trans, 51 Trehalose, 576 Triacetamide, 265 acetin, 475 acetonamine, 219 acetonine, 219 acetylbenzene, 319 amidophenol, 217 aminopropane, 477 azo-acetic acid, 367 azole, 228 azo-trimethylene tricarboxylic acid, 367 Tribrom acetic acid, 275 acrylic acid, 281 aldehyde, 198 benzene, 106 butyric acid, 276 ethidene glycol, 198 hydrin, 474 lactic acid, 340, 349 methyl -ketol, 482 pyroracemic acid, 235, 370 succinic acid, 452 Tributyrin, 475 carballylic acid, 517 carbamidic acid, 403 carbimide ester, 420 chloracetal, 200 aldehyde, 197 Trichloracetic acid, 198, 274 Trichloraceto-acrylic acid, 382 Trichloracetyl chloride, 275 tetrachlorcrotonic acid, 221 trichlorcrotonic acid, 383 Trichloracrylic acid, 281 amide, 510 butyl-alcohol, 126, 569 butyraldehyde, 199, 340 butyric acid, 276 ethane, 103, 316 ether, 135 ethidene methane, 395 ethyl alcohol, 124, 569 hydracetyl acetone, 213, 318 hydrin, 474 isopropyl alcohol, 125 lactic acid, 340, 485 trichlor ethidene ether ester, 198, 340 methane (see Chloroform). meth)l paraconic acid, 492, 550 sulphuric acid, 393 Trichloroxybutyric acid, 487 phenomalic acid, 382 propane, 474 pyroracemic acid, 370 valerolactinic acid, 341, 350 Tricosane, 86 cyanic acid, 419 cyanogen chloride, 421 decane, 86 decylic acid, 249, 265, 268 diethylamine-phosphinic oxide, 165 ethidene disulphone-sulphide, 203 trisulphone, 203 ethoxyacetonitrile, 437 ethylamine, 168, 172 oxide, 172, 178 arsine compounds, 178 borine, 180 Triethylene glycol, 295 Triethylguanidine, 412 hydroxylamine, 172 Triethylin, 476 isomelamide, 428 melamine, 428 methane, 85 phloroglucin, 259 phosphine compounds, 174, 178 silicon compounds, 181 stibine compounds, 179 sulphine iodide, 150 thio-urea, 409 urea, 399 Triformoxime, 206 ,glycolamidic acid, 356, 403 halose, 576 hydrocyanic acid, 231 iodo-acetic acid, 235, 275 benzene, 106 isoamylene, 93 butyric acid, 521 ketovaleric acid, 521 Trimesic ester, 361 Trimethine triazimide, 367 Trimethyl acetaldehyde, 196 acetic acid, 128, 246, 249, 259, 265, 268 amine, 164, 167 arsine compounds, 178 benzene, 98 borine, 1 80 carbinol, III, 126 dihydro hydridin-dicarboxylic ester, 206 ethylene, 93 oxide, 299 glutaric acid, 454 glycocoll (see Betaine), 310 6 24 INDEX. Trimethyl isomelamine, 428 melamine, 428 methane, 85 phosphine compounds, 174 pyrazoline, 220 pyroracemic acid, 212, 2 1 6, .337, 370 stibine derivatives, 179 succinic acid, 446 sulphine compounds, 151 tricarballylic acid, 518 vinyl ammonium hydroxide, 169, 309 xanthine, 515 Trimethylene, 89 bromide, 102, 302, 303, 45 2 , 53 2 carboxylic acids, 279, 367, 4$6, 458,464, 486, 518, S3 2 chloride, 303 chlorobromide, 276 cyanide, 293 derivatives, 78 diamine, 313 dicarboxylic acid, 456 dimalonic acid, 456 diphthalimide, 312 disulphone, 305 disulphide, 203 glycol, 295 chlorhydrin, 301 diacetate, 304 haloids, 303 imide, 314 iodide, 303 oxide, 214, 299 triamine, 206 trisulphone, 203 urea, 40x5 Trimyristin, 475 Trinitrophenol, 387 Trinitroacetonitrile, 235, 437 Trinitrobenzene, 477 Trinitromethane, 235 Triolein, 475 Trional, 218 Trioses, 477, 534 Trioxethylamine, 308 imidopropane, 479 Trioxoheptan. 479 Trioxyadipic acid, 538 \mtyric acid, 521 glutaric acid, 538, 563 methylene, 194, 200, 552 Tripalmitin. 475 saccharides. 577 Trisodium-phloroglucin-tricarboxylic es- ter, 440 stearin, 475 sulphone acetone, 218 thio-acetaldehyde, 203 acetone, 218 carbonic acid, 389, 392 cyanuric ester, 427, 428 formaldehyde, 203 ketones, 203, 218 Trypsin, 583 Turanose, 576 Types, chemical, 34 mechanical, 35 mixed, 36 principal, 35 secondary, 36 Tyrosin, 69, 581, 586 U UNDECANE, 86 Undecanonic acid, 382 Undecolic acid, 284, 288, 382 Undecylenic acid, 284, 286, 481 Undecylic acid, 249, 250 Ur-acids, 505 Uracyl, 505 Uramido-crotonic ester, 513 Uramil, 507, 513 Urazole, 405 Urea, 396 alkylic, 398 chlorides, 395 Ureides, 400, 505 Ureo-ethane, 399 (Jrethane acetic acid, 395 Urethanes, 394, 403 Uric acid, 510, 511 synthesis of, 513 Urobutyrchloralic acid, 199, 569 Urochloralic acid, 198, 569 Uroxanic acid. 512 Uvic acid, 370 Uvitic acid, 370 Uvitonic acid, 371 VALENCE, 36 Valeraldehyde, 196 Valeriana officinalis, 248 Valeric acid, 248, 256, 265, 268 Valeroin, 317 Valero-lactam, 360 lactone, 344 345 carboxylic acid, 494 INDEX. Valeryl thiocarbimide, 425 Valerylene, 98 Vapor density, determination of, 27 Vaporimeter. 123 Vapor pressure, lowering of, 30 Vaselines, 88 Vegetable albumin. 583 gum, 579 Vicia faba minor. 509 sativa, 509 Vinaconic acid, 486 Vinol 130 Vinyl alcohol, 53, 130 form, 319 amine, 169 bromide, 95, 105 J| chloride, 105 cyanide, 280 diacetonamine, 219 ether, 136 ethyl ether, 136; of ethylene mer- captan , 304 sulphide, 149 trimethyl ammonium hydroxide, 169. 309 Viol uric acid, 509 Vital force. 17 Vitellin, 583' Volemite, 542 Vulcanization of caoutchouc, 390 Wood gum. 579 spirit, 1 17 sugar, 536 vinegar, manufacture, 245 Wool fat. 588 Wurtz's reaction, 84, 92 I XANTHANE hydride, 422 Xanthic disulphide, 392 Xanthine, 513, 514 Xanthochelidonic acid, 538 Xanthogenamic acid, 406 Xanthogenamides, 406 Xanthogenic acids, 390, 391 XanthoproteTc reaction, 582 rhamnine. 536 Xeronic acid, 466 Xylite, 534 Xylonic acid, 537 Xyloquinone, 322 Xylose, 536 Xylotrioxyglutaric acid, 537 Xylylene bromide, 531 YELLOW prussiate of potash, 232 W WAXES. 130, 251, 256 Weiss beer, 122 Wine, 122 spirit, 118 vinegar, 244 ZlNC alkyls, 184 syntheses, 82, 92, 114, 210, 244, 259 chloride, 92, 138 53 THIS BOOK IS ON THE LAST DATE BELOW -T ^TH ns CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. 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