THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA DAVIS GIFT OF MISS HELEN R. BLASDALE ■<•*;*. ■ Digitized by the. Internet Archive in 2007 with funding from Microsoft Corporation http://www.archive.org/details/determradiclesOOmeyerich DETERMINATION OF RADICLES IN CARBON COMPOUNDS. BY Dr. H. MEYER, Docent and Adjunct of the Imperial and Royal German University, Prague. AUTHORIZED TRANSLATION BY J. BISHOP TINGLE, Ph.D., F.C.S., Instructor of Chemistry at the Lewis Institute, Chicago, III. FIRST EDITION. FIRST THOUSAND. NEW YORK: JOHN WILEY & SONS. London : CHAPMAN & HALL, Limited. 1899. LIBRARY ^UNIVERSITY OF CALIFORNIA DAVIS Copyright, 1899, BY BISHOP TINGLE. ROBERT DRUMMOND, PRINTER, NEW YORK, AUTHOR'S PREFACE. This English edition of my " Anleitung zur quanti- tativen Bestimmung der organischen Atomgruppen " has been prepared by Dr. J. Bishop Tingle, to whom I am greatly indebted for the care he has bestowed on it. I have endeavored to bring it into conformity with the present state of the science by various cor- rections and additions. It has been further improved by certain changes in arrangement which Dr. Tingle has made, and he has also added various notes. The present edition is thus a decided advancement on the German one, and I trust that in its new form it may gain many new friends whilst retaining its old ones. Dr. Hans Meyer. Prague, October 1899. iii TRANSLATOR'S PREFACE. THE success of the German edition of Dr. Meyer's book was only one of the reasons that led to the prep- aration of this translation. The quantitative side of organic chemistry, apart from elementary analysis, is almost always neglected in the ordinary courses of in- struction, and when the need for it arises, in the pros- ecution of research work for instance, it is difficult to obtain a comprehensive view of the methods which are available without undue expenditure of time. This little work supplies, for the first time, a systematic treatment of these methods which, it is hoped, may help to remove this drawback and may also encour- age the introduction of some quantitative work into the college courses of organic preparations, since such a departure could scarcely fail to be beneficial in various ways to the student. From the translator's experience with the German edition he believes that the present one will be serviceable to instructors and senior students of organic chemistry. Considerable care has been bestowed on the proof-sheets, and it is hoped that the errors which may have escaped notice are not too glaring. Lewis Institute, Chicago, III., October 1899. CONTENTS. CHAPTER I. I PAGE Introductory. Determination of Hydroxyl, OH i Introductory, I. Determination of hydroxyl, 3. Acy- lation, 3. Preparation of acetyl derivatives, 5. (A) By acetyl chloride, 5. (B) By acetic anhydride, 7. (C) By glacial acetic acid, 8. Isolation of acetyl derivatives, 9. Determination of the acetyl groups, 9. (A) Hydrolytic methods, 9. (B) Additive method, 14. (C) Potassium acetate method, 14. (D) Distillation method, 15. Ben- zoyl derivatives, 17. (A) Preparation from benzoyl chloride, 18. (B) Preparation from benzoic anhydride, 21. Preparation of substituted benzoic acid deriva- tives and of phenylsulphonic chloride, 22. Acylation by means of substituted benzoic acid derivatives and of phenylsulphonic chloride, 23. Analysis of benzoyl derivatives, 24. Acylation by means of other acid rad- icles, 27. Alkylation of hydroxyl groups, 28. Prepara- tion of benzyl derivatives, 28. Preparation of carba- mates by means of carbamyl chloride, 29. Preparation of diphenylcarbamyl chloride, 30. Preparation of phe- nylcarbamic acid derivatives, 31. Preparation of phenyl- isocyanate, 31. Action of phenylisocyanate on hydroxyl derivatives, 31. CHAPTER II. 1 1 Determination of Methoxyl, CH3O-, Ethoxyl, C a H 6 0-, and Carboxyl, CO. OH 33 Determination of methoxyl, S. Zeisel's method, 33. vii Vlll CONTENTS. paGH For non-volatile substances, 36. For volatile com- pounds, 38. Modified method, 39. Method for the differentiation of methoxyl and ethoxyl, 40. Deter- mination of ethoxyl, 41. Determination of carboxyl, 41. (A) Analysis of metallic salts, 42. (B) Titra- tion of acids, 43. (C) Etherification, 44. (D) Elec- trolytic conductivity of sodium salts, 46. Indirect meth- ods for the determination of the basicity of acids, 51. (i) Carbonate method, 51. (ii) Ammonia method, 52. (iii) Hydrogen sulphide method, 52. (iv) Iodine-oxygen method, 57. CHAPTER III. Det ermination of Carbonyi 60 Preparation of phenylhydrazones, 60. Preparation of substituted hydrazones and of parabromophenylhydra- zine, 63. Indirect method, 65. Preparation of oximes, 70. Preparation of semicarbazones, 74, 77. Preparation of semicarbazide salts, 75. Preparation of amidoguani- dine derivatives, 78. Paramidodimethylaniline deriva- tives, 80. CHAPTER IV. Determination of the amino group, 81. Determination of aliphatic amines (i) nitrous acid method, 81. (ii) Anal- ysis of salts and double salts. 82. (iii) Acetylation, 83. Determination of aromatic amines: (i) Titration' of the salts, 83. (ii) Preparation of diazo-derivatives: {a) con- version into an azo dye, 84. {b) Indirect method, 85. (c) Azoimide method, 86. (d) Sandmeyer-Gattermann's reaction, 87. (iii) Analysis of salts and double salts, 89. (iv) Acetylation, 89. Determination of the nitrile group, 90. Determination of the amido group, 91. Determi- nation of the imide group: (i) Acetylation, 92. (ii) Alky- lation, 93. (iii) Analysis of salts, 94. (iv) Elimination of imidogen as ammonia, 94. Determination of methyl imide, 94. Determination of ethyl imide, 99. Differ- entiation of the methyl imide and ethyl imide groups, 99. CONTENTS. IX CHAPTER V. PAGE Determination of the diazo-group (A) Aliphatic diazo-compounds : (i) Titration with iodine, ioo. (ii) Analysis of the iodine derivative, ioi. (iii) Determina- tion of the nitrogen in the wet way, ioi. (B) Aromatic diazo-compounds. Diazonium derivatives, 103. Deter- mination of the hydrazide group, 103. (i) By oxidation, 104. (ii) Iodometric method, 106. Determination of the nitrogroup. (A) Titration method, 106. (i) Method for non-volatile compounds, 108. (ii) Modifications for vola- tile compounds, 10S. (B) Diazo-method, 109. Determi- nation of the iodoso- and iodoxy-groups, 109. Deter- mination of the peroxide group, no. The iodine number, in. Appendix. Table of the weights of a cubic centi- meter of hydrogen, 116. Tension of aqueous vapor, 118. Table for the value of , 118. Index of 1000 — a authors, 121. Index of subjects, 129. ABBREVIATIONS. The following abbreviations have been used in the bibliographical references : Am. Chem. Journ. American Chemical Journal. Ann. Liebig's Annalen der Chemie und Pharmacie. Ann. de Ch. Ph. Annales de Chimie et de Physique. Arch. Pharm. Archiv der Pharmacie. B. Berichte der Deutschen chemischen Gesell- schaft. Bull. Bulletins de la Societe Chimique de Paris. C. Chemisches Centralblatt. Ch. R. Chemische Revue. Ch. Ztg. Chemiker-Zeitung. Ch. N. Chemical News. C. r. Comptes rendus de l'Academie des sciences (Paris). Dingl. Dingler's polytechnisches Journal. Gazz. Gazzetta chimica italiana. H. Beilstein, Handbuch. J. Jahresbericht uber die fortschritte der Chemie. J. Am. Journal of the American Chemical Society. Journ. Chem. Soc. Journal of the Chemical Society of London. J. pr. Journal fur praktische Chemie. M. Monatshefte ftlr Chemie. M. & J. V. Meyer and P. Jacobson, " Lehrbuch der organischen Chemie." Rec. Recueil des travaux chimiques des Pays-Bas. S. Seelig, " Organische Reaktionen und Re- agentien." W. Ann. Wiedemann's Annalen der Physik und Chemie. Z. Zeitschrift fur physikalische Chemie. Z. An. Zeitschrift fur anorganische Chemie. Z. anal. Zeitschrift fur analytische Chemie. Z. ang. Ch. Zeitschrift fiir angewandte Chemie. Z. f. Ch. Zeitschrift flir Chemie. Z. physiol. Ch. Zeitschrift fiir physiologische Chemie. Z. Rub. Zeitschrift des Vereines fiir Riibenzucker- industrie. DETERMINATION OF RADICLES IN CARBON COMPOUNDS. Chapter T. INTRODUCTORY. DETERMINATION OF HYDROXYL (-OH). THE quantitative analysis of inorganic compounds, as usually performed, consists almost exclusively in the determination of ions, since in the present state of the science this generally suffices for the identification of the substance ; but to attain the same end in the case of organic bodies the elementary analysis re- quires supplementing by other methods. The per- centage composition gives no information about the relative arrangement of the atoms in the molecule, but the demand for methods of analysis which will yield such knowledge increases with our growing in- sight into the constitution of carbon compounds. To supply this want certain "quantitative reactions" have been applied for the determination of special groups of atoms ; they are widely, but almost exclu- sively, employed by technologists in the analysis of such substances as fats, waxes, resins, ethereal oils, caoutchouc, glue, paper, etc., and the results are 2 RADICLES IN CARBON COMPOUNDS. known as the "acid number," "saponification num- ber," "iodine number," "methoxyl number," " ace- tyl number," " carbonyl number," etc. The deter- mination of such "numbers" or " values" obtained by the action of some reagent on a known weight of substance is frequently insufficient for scientific investigation, this renders it necessary to work out a special process for each group of organic com- pounds in order to determine the radicles which are present. The reactions of organic compounds are only in part ionic ; usually they are conditioned by the con- figuration and state of equilibrium of the molecule, and consequently a reaction which readily occurs with one compound may totally fail with another of very similar constitution on account of stereoisomerism ; or, by substitution, a radicle may approximate more or less closely to the character and functions of another one. In these cases the quantitative separation of the compounds is more difficult, and can frequently only be accomplished by differences in crystallizing power, or by the preparation of derivatives which can be volatilized without decomposition. Since the course of a particular reaction of an inor- ganic compound is only conditioned by the behavior of the ions which are to be determined, it follows that the analytical methods are in a sense independent of the nature of the compounds investigated, and conse- quently of very wide application. The matter is far otherwise with organic compounds : there are very few processes which, like Ziesel's method for deter- mining methoxyl, can be applied almost universally. DETERMINATION OF HYDROXYL. 3 Usually, then, it becomes necessary for the analyst himself to select the method most appropriate for his special purpose, or, perhaps by a combination of several, to devise one which may lead to the desired result. The successful methods hitherto proposed for the determination of organic radicles have been collected together in this work, and it is hoped that they may serve to indicate the direction in which research may be successfully prosecuted for the dis- covery of new ones applicable to hitherto unforeseen conditions. DETERMINATION OF HYDROXYL (-OH). The determination of the hydroxyl radicle in or- ganic compounds consists in the preparation of deriva- tives by the following methods: (I.) ACYLATION. — This consists in the introduc- tion into the hydroxyl compound of the radicle of one of the acids mentioned below: Acetic acid ; Benzoic acid and its substitution products ; Phenylsulphonic acid. Of less frequent employment are the radicles of Propionic acid ; Isobutyric acid ; Phenylacctic acid. (II.) ALKYLATION. — Confined usually to the prep- aration of benzyl derivatives. (III.) The preparation of CARBAMATES. (IV.) The formation of ESTERS OF PHENYLCAR- BAMIC ACID. 4 RADICLES IN CARBON COMPOUNDS. As a rule, attention is first directed to the prepara- tion of an acetyl or benzoyl derivative, the former usually by Liebermann & Hermann's method (see page 7), the latter by that of Loss'en or Schotten- Baumann (see page 18). Not infrequently, however, it becomes necessary to resort to one of the other forms of procedure in order to determine the consti- tution of the body under investigation. As the groups NH„ NH 2 and SH are all capable of acylation, care is required to avoid confusion if the original compound contains nitrogen or sulphur. Instances are known of acetylation taking place in the absence of hydroxyl and of the groups just referred to, thus diacetylhydroquinol is formed from quinone, acetic anhydride, and sodium acetate; 1 tetrachloroquinone and acetyl chloride yield diacetyltetrachlorohydro- quinol; 3 whilst pyrogallophthalei'n (gallein), which contains only two hydroxyl groups, forms a tetracetyl and tetrabenzoyl derivative. 3 Acetylating reagents frequently cause isomerization or polymerization, and sometimes lead to the production of anhydrides, etc. ; thus benzhydrylacetocarboxylican hydride is obtained from the isomeric orthocinnamocarboxylic acid by the action of acetic anhydride and sodium acetate, 4 and cantharic acid when heated in a sealed tube with acetyl chloride yields isocantharidin. 6 In view of these and similar facts, care should be taken to hydro- lyse the presumptive acetyl derivative and identify the product with the original substance ; should this 'Sarauw, B. 12, 680. 8 Graebe, Ann. 146, 13. 'Buchka, B. 14, 1327. 4 Benedikt and Ehrlich, M. 9, 529. Anderlini and Ghiro, B. 24, 1998. DETERMINATION OF HYDROXYL. 5 not be possible, then proof must be obtained that the derivative does actually contain the acid radicle, the introduction of which has been attempted. I. METHODS OF ACETYLATION. (i) PREPARATION OF ACETYL DERIVATIVES. The following reagents are employed for the prepa- tion of acetyl derivatives from organic compounds containing hydroxyl groups: (A) Acetyl chloride. (B) Acetic anhydride, sodium acetate. (C) Glacial acetic acid. (D) Chloracetyl chloride. (A) Acetylation by Means of Acetyl Chloride. (a) Many hydroxyl derivatives react with acetyl chloride when simply mixed or digested on the water- bath. It is convenient to dissolve the substance and the chloride in benzene, and boil the solution until the evolution of hydrochloric acid ceases. If there is no danger of the hydrogen chloride causing secondary reactions (hydrolysis), of which an interesting case has been recorded, 1 the substance may be heated with the chloride in a sealed tube without solvent. Certain dibasic hydroxy acids of the aliphatic series, such as mucic acid, which are not changed with acetyl chloride alone, frequently react with it on the addition of zinc chloride. 2 In "general, it may be stated that acetyl 1 Herzig and Schiff, B. 30, 397. Cf. Bamberger and Landsiedl, M. 18, 307. 2 S., p. 258. 6 RADICLES IN CARBON COMPOUNDS. chloride only reacts readily with alcohols and phenols, but, as it may lead to the production of anhydrides from polybasic acids, these are usually employed in the form of esters, which has the additional advan- tage of yielding products that are much more easily distilled than the corresponding derivatives of the acids themselves. 1 (b) The following method a is frequently more con- venient than the "acid" acetylation just described. The substance is dissolved in ether or benzene, and digested with the necessary quantity of acetyl chloride and dry alkali carbonate, the latter being in the pro- portion necessary to form a hydrogen salt as repre- sented by the equation: R.OH + CH3.COCI + K a CO s »-> R.O.CO.CH, + KC1 + KHCO3. (c) Acetylation by means of acetyl chloride and aqueous alkali is described on p. 20. (d) It is often convenient to allow the acetyl chlo- ride to react with the compound under investigation in pyridine solution. 3 (e) Diacetylacetone could only be acetylated by al- lowing its barium salt to react with acetyl chloride at the ordinary temperature.* (/) Instead of acetyl chloride phosphorus trichlo- ride, or preferably the oxychloride, or phosgene may be employed ; they are allowed to react on a mixture of the substance and acetic acid in the proper propor- 'Wislicenus, Ann. 129, 17. s L. Claisen, B. 27, 3182. 8 A. Deninger, B. 28, 1322. 4 Feist, Ibid. 28, 1824. DETERMINATION OF HYDROXYL. 7 tion. 1 Thus, for example, phenol is readily acety- lated by heating it at 8o° with an equimolecular proportion of acetic acid and adding phosphorus oxy- chloride (J molecule) gradually, by means of a dropping funnel. When hydrogen chloride is no longer evolved the product is poured into cold aqueous soda solution ; after further washing with highly dilute alkali it is treated once with water, dried by means of calcium chloride, and distilled. (B) Acetylation by Means of Acetic Anhydride. (a) The substance is usually boiled with 5-10 parts of anhydride, or heated with it in a sealed tube during several hours. (b) Not infrequently the substances must only be allowed to react during a short time, at a compara- tively low temperature. Bebirine, for instance, is readily acetylated when digested with the anhydride during a short time at 40°-5o°, but by its prolonged action amorphous substances are formed. 3 (c) The substance may be mixed with an equal weight of dry sodium acetate, and 3-4 parts of the anhydride, and boiled for a short time in a reflux apparatus; 3 in the case of small quantities of substance 2-3 minutes boiling may suffice. The action ap- pears to depend on the production of a sodium salt of the compound under examination, which then re- acts with the anhydride. This method yields, on the whole, the most trustworthy results of any, and sel- -*— — c 1 J. pr. 25, 282; 26, 62; 31, 467. 5 B. 29, 2057. 3 C. Lieberjhann and O. Hormann, Ibid, 11, 1619. 8 RADICLES IN CARBON COMPOUNDS. dom fails to give completely acetylated derivatives. It fails in the case of the tf-hydroxyl of the hydroxy- quinolines, 1 though these compounds yield benzoyl derivatives. (//) A mixture of acetic anhydride and acetyl chloride may be used, or the action of the anhydride may be started by means of a drop of concentrated sulphuric acid. 2 (e) The addition of zinc chloride 3 and of stannic chloride 4 has also been recommended. (C) Acetylation by Means of Glacial Acetic Acid. Acetylation, especially that of alcoholic hydroxyl groups, may often be accomplished by heating the substance with glacial acetic acid, under pressure if necessary; the addition of sodium acetate is also advantageous, and, in some cases, this is the only method which gives the desired result. Thus, cam- phorpinacone yields a chloride when treated with acetyl chloride, and is not changed by boiling acetic anhydride, but when it is boiled .with glacial acetic acid for a short time, a stable acetyl derivative is formed, and an isomeric " labile" one by the action of the acid at the ordinary temperature during twenty-four hours. 5 (D) Acetylation by Means of Chloracetyl Chloride. This reagent has also been employed occasionally. 8 1 J. Diamant, M. 16, 770. Cf. La Coste and Valeur, B. 20, 1822. 2 Franchimont, B. 12, 1941. 3 Franchimont, C. r. 89, 711; B. 12,2058. 4 H. A. Michael, B. 27, 2686. 5 Beckmann, Ann. 292, 17. 6 Klobukowsky, B. 10, 881. Cf. Ibid. 31, 2790. DETERMINATION OF HYDROXYL. 9 II. ISOLATION OF THE ACETYL DERIVATIVES. Acetyl derivatives are isolated by pouring the product of the reaction into water. The excess of acetic acid may also be removed by the addition of methylic alcohol to convert it into methylic acetate, which is then volatilized ; residual acetic anhydride is separated by distillation under reduced pressure. Acetyl derivatives, soluble in water, may often be pre- cipitated by the addition of solid sodium carbonate, or by extracting the solution with chloroform or benzene. Ethylic acetate frequently proves to be an excellent medium for the subsequent recrystallization of the acetyl product. III. DETERMINATION OF THE ACETYL GROUPS. The various acetyl derivatives of a compound usually differ little in percentage composition, so that elementary analysis seldom affords information as to the number of acetyl groups which have entered the original molecule; thus, the mono-, di-, and tri- acetyl derivatives of the trihydroxybenzenes have an identical percentage composition. In such cases the acetyl groups must be eliminated and the acetic acid formed determined directly or indirectly. (A) Hydrolytic Methods. The following reagents are employed for the hydrolysis of acetyl compounds : IO RADICLES IN CARBON COMPOUNDS. (a) Water. (b) Potassium hydroxide, sodium hydroxide, (c) Barium hydroxide. (d) Magnesia. (e) Hydrochloric acid. (f) Sulphuric acid. (g) Hydriodic acid. (a) Some acetyl derivatives are hydrolysed by heating with water under pressure; thus butenyltri- acetin, C 4 H 7 (C 2 H 3 2 ) 3 , is completely hydrolysed by heating it with forty parts of water at 160 in a sealed tube, and the liberated acetic acid may be titrated. 1 Diacetylmorphine also loses one aceytl group by boiling it with water, 2 and acetyl dihydroxypyridine is still more unstable. 3 (b) Hydrolysis by means of potassium hydroxide or sodium hydroxide is specially useful for the analysis of fats. The compound (1-2 grams) is gently boiled on the water-bath during fifteen min- utes, in a wide-necked flask of 1 00-150 cc capacity, with alcoholic potash (25-50 cc) of known strength, which should be about N/2. During the heating the neck of the flask is covered with a cold funnel ; at the conclusion of the hydrolysis phenolphthale'in is added, and the excess of alkali determined by means of N/2 hydrochloric acid. 4 The method may also be employed for the determination of the molecular weight of the aliphatic alcohols. This is obtained 1 Lieben and Zeisel, M. 1, 835. 8 Wright-Becket, Journ. Ch. Soc. 12, 1033. Danckwortt, Arch. Pharm. 226, 57. 3 M. 18, 619. * Benedikt and Ulzer, M. 8, 41. DETERMINATION OF HYDROXYL. II 56IOO . from the expression M = — ^ 42, where M is the molecular weight, and V the number of milligrams of potassium hydroxide required to hydrolyse 1 gram of the acetyl derivative. If the compound is affected by air, the hydrolysis is carried out in an atmos- phere of hydrogen; 1 should the original compound be insoluble in dilute hydrochloric acid, the acetyl derivative may be boiled with aqueous potash, the product acidified, and the precipitate weighed. 3 (c) Barium hydroxide may be employed in many cases where potash causes decomposition, thus hematoxylin yields formic acid when boiled with highly dilute alkali, but barium hydroxide readily hydrolyses its acetyl derivatives without further decomposition. 3 One method of procedure 4 is to boil the compound under investigation with the hydroxide during 5-6 hours in a reflux apparatus. The product is filtered, the filtrate treated with car- bonic anhydride in excess, again filtered, and the filtrate evaporated. The residue is dissolved in water, the liquid filtered, and, after washing, the barium in the filtrate is determined as sulphate. Since all the above operations are conducted in glass vessels, some alkali from these may neutralize a por- tion of the acetic acid and a correction thus becomes necessary. This is obtained by concentrating the filtrate from the barium sulphate in a platinum dish; 1 Klobukowsky, B. 10, 882. 2 Vortmann, "Anleitung zur chemischen Analyse organischer Stoffe," p. 59. 8 Erdmann and Schultz, Ann. 216, 234. • Herzig, M. 5, 86. 12 RADICLES IN CARBON COMPOUNDS. when the excess of sulphuric acid has been volatilized, the residue is treated with pure ammonium carbonate until its weight becomes constant. It is now dissolved in water, the silica removed, and the sulphates in the filtrate determined as barium sulphate, the weight of which is added to that first found. If the hydrolysis, etc., can be carried out in vessels of silver, 1 the above correction is unnecessary. The action of the barium hydroxide solution is promoted by the previous addition to the substance of a few drops of alcohol. a (d) Magnesia is generally employed in the follow- ing manner: 3 Ordinary "ignited magnesia," and the basic carbonate (magnesia alba) are both unsuitable, as they contain alkali carbonates which are difficult to remove. The magnesia is prepared from the sul- phate or chloride, which must be free from iron ; the solution is treated with alkali hydroxide in quantity insufficient to cause complete precipitation ; after thorough washing the magnesia is retained as a paste underwater. The acetyl derivative (i-i. 5 grams) is intimately mixed with the magnesia paste (about 5 grams) and a little water, and transferred, together with water (100 cc), to a flask of resistant glass. The mixture is boiled in a reflux apparatus during 4-6 hours, although usually the hydrolysis is completed in 2-3 hours. The liquid is concentrated in the flask to a third of its original volume, cooled, filtered by means of a pump, the insoluble portion washed, and the filtrate and washings treated with ammonium 1 Lieben and Zeisel, M. 4, 42; 7, 69. 2 Barth and Goldschmiedt, B. 12, 1237. ■ H. Schiff, Ibid. 12, 1531. Ann. 154, n. DETERMINATION OF HYDROXYL. 1 3 chloride, ammonium hydrate, and ammoniacal sodium phosphate. The magnesium ammonium phosphate, after standing during twelve hours, is filtered, dissolved in dilute hydrochloric acid, and reprecipitated by means of ammonium hydrate ; I part of Mg a P a O, = 0.774648 parts of C 2 H,0. The solubility of magnesia in highly dilute solutions of magnesium acetate is too small to require a correction. Even "insoluble" acetyl derivatives may be hydrolysed by magnesia, provided that they are in a finely divided state, the boiling being prolonged to twelve hours if necessary. The magnesia method is advantageous in cases where the use of alkali causes decomposition and the pro- duction of colored substances which render titration uncertain. (e) If hydrochloric acid (sulphuric acid) is without action on the hydroxyl compound, the acetyl deriva- tive is heated with a known quantity of N/i acid in a sealed tube or pressure-flask at I20°-i50°, and the liberated acetic acid titrated. 1 (f) Hydrolysis by means of sulphuric acid is espe- cially advantageous when the original substance is insoluble in it. The acid employed should be free from oxides of nitrogen and contain 75 parts of con- centrated acid in 32 parts of water. The dilute acid (10 cc) is mixed in a flask with a weighed quantity of the acetyl derivative (about 1 gram), which, if neces- sary, may be previously moistened with three or four drops of alcohol ; the mixture is warmed on'a hot but not boiling water-bath during a half hour, diluted with 1 Schiitzenberger, Ann. de Ch. Ph. 84, 74. Herzfeld, B. 13, 266. Schmoeger, Ibid. 25, 1453. 14 RADICLES IN CARBON COMPOUNDS. eight volumes of water, then boiled during 3-4 hours on the water-bath, and allowed to remain during twenty-four hours at the ordinary temperature. The precipitated hydroxyl derivative is then collected on a filter. x,a Should the hydroxyl derivative not be completely insoluble in the dilute acid a blank experiment must be made and the correction intro- duced.' (<£") Hydriodic acid has also been employed for the hydrolysis of acetyl derivatives. 8 (B) Additive Method. 4 This may be regarded as complementary to the method described under/". In cases where the acetyl derivative is insoluble in cold water, and the acety- lation proceeds quantitatively, the yield of product from a given weight of hydroxyl compound gives a measure of the number of acetyl groups introduced. This method has recently been applied to the investi- gation of the acetylation products of tannic acid. 6 (C) Weighing the Potassium Acetate." This is applicable to compounds yielding potas- sium salts insoluble in absolute alcohol. The acetyl derivative (1-2 grams) is boiled with a slight ex- cess of potassium hydroxide solution until it is com- 1 Liebermann, B. 17, 1682. Herzig, M. 6, 867-890. 8 Ciamician and Silber, B. 28, 1395. 8 Ciamician, Ibid. 27, 421, 1630. 4 Goldschmiedt and Hemmelmayr, M. 15, 321. 6 H. Schiff, Ch. Ztg. 20, 865. • Wislicenus, Ann. 129, 175. DETERMINATION OF HYDROXYL. 1$ pletely hydrolysed, water being added to replace that evaporated. The remaining alkali is neutralized with carbonic anhydride, the liquid evaporated as com- pletely as possible on the water-bath, and the residue thoroughly extracted with absolute alcohol. The alcoholic solution is evaporated to dryness and the residue again extracted, any insoluble matter being re- moved and well washed, and the liquid evaporated in a tared vessel. The dried potassium acetate remain- ing is then cautiously fused, allowed to cool over sul- phuric acid, and weighed. (D) Distillation Method. Fresenius 1 first suggested that the acetic acid from acetates could be liberated with phosphoric acid and determined by distillation, with or without the help of steam. The method was then applied by various chemists to the hydrolysis of acetyl deriva- tives, but since they replaced the phosphoric acid by sulphuric acid their results were not satisfactory. 2 Subsequently the use of phosphoric acid was again proposed. 3 The acetyl product is hydrolysed by means of alkalis or barium hydroxide, acidified at the ordinary temperature with phosphoric acid, filtered, and well washed ; the filtrate and washings are then distilled until the distillate is completely free from acid, fresh water being introduced into the retort from 1 Z. anal. Ch. 5, 315; 14, 172. * Erdmann and Schulze, Ann. 216, 232. Buchka and Erk, 18, 1142. Schall, Ibid. 22, 1561. 3 Herzig, M. 5, go. 1 6 RADICLES IN CARBON COMPOUNDS. time to time as may be necessary. The distillation is at first carried out over a flame and subsequently from an oil-bath, the temperature being allowed to rise to I40°-I50°, or a water-bath may be employed, in which case the pressure is reduced. 1 The connections must all be of caoutchouc, as corks would absorb acetic acid, and the alkali and acid employed must be free from nitrates or nitrites. The presence of chlorides is not hurtful, as these do not liberate hydrogen chloride in presence of the phosphoric acid, which is one advan- tage it possesses over sulphuric acid. 3 The distillate is treated with baryta water in excess, and concen- trated in a platinum dish, the excess of barium re- moved by means of carbonic anhydride, and the fil- trate evaporated to dryness; water is then added, the liquid filtered, the insoluble portion well washed, and the barium in the filtrate and washings determined as sulphate, I gram BaS0 4 = 0.5064 gram C a H,0, or 0.5070 gram C 2 H 4 2 . The acetyl groups in acetylated gallic acids s were determined by mixing the substance (3-4 grams) with pure alcohol (5 cc) and sodium hydroxide (2-3 grams) dissolved in water (15 cc). After the hydrolysis was completed, the alcohol was dissipated, the residue acidified with phosphoric acid, the acetic acid driven over in a current of steam, and its amount determined by titrating the distillate with sodium hydrate solu- tion, phenol'phthale'i'n being used as indicator. One source of error in this method arises from carbonic 1 H. A. Michael, B. 27, 2686. 2 R. and H. Meyer, Ibid. 28, 2967. » P. Sisley, Bull. Soc. Chim. III. 11, 562. Z. anal. Ch. 34,466. DETERMINATION OF HYDROXYL. 1 7 anhydride, which is always present in the sodium hydrate, and is often produced by the hydrolysis itself; it naturally volatilizes together with the acetic acid. The difficulty may be avoided by heating the neutralized liquid to boiling, adding a very small quantity of N/i acid, again boiling, and then neutral- izing, the process being repeated until the neutralized liquid ceases to become red on boiling; this shows that all the carbonates are decomposed and no loss of acetic acid need be apprehended. It has been sug- gested ' that, after the hydrolysis, elimination of the alcohol, ^and acidification by means of phosphoric acid, the liquid should be boiled in a reflux apparatus until the carbonic anhydride is removed, the subse- quent operations being similar to those above described. Sources of error in this method are described on p. 26. a BENZOYL DERIVATIVES, (i) PREPARATION OF BENZOYL DERIVATIVES. The following reagents are employed for the intro- duction of the benzoyl radicle into hydroxyl com- pounds: Benzoyl chloride ; Benzoic anhydride, sodium benzoate ; p-Brombenzoyl chloride, p-Brombenzoic anhydride ; o-Brombenzoyl chloride ; m-Nitrobenzoyl chloride ; Phenylsulphonic chloride. 1 P. Dobriner, Z. anal. Ch. 34, 466, foot-note. * Cf. Goldschmiedt and Hemmelmayr, M. 14, 214; 15, 319. 1 8 RADICLES IN CARBON COMPOUNDS. (A) Preparation of Benzoyl Derivatives by Means of Benzoyl Chloride. (a) The ''acid" method consists in heating the sub- stance with the chloride at i8o° during several hours in a reflux apparatus; it is not advisable to employ a sealed tube unless there is assurance that the hydro- chloric acid will not cause secondary reactions nor, in the case of nitrogenous compounds, combine with them to form hydrochlorides which would then cease to react f when this may occur the calculated quantity of chloride is employed, and the heating continued during about four hours at ioo°-iio°. (b) The preceding method has been largely super- seded by the use of the chloride in dilute aqueous al- kaline solution. 2 It has been widely applied, 3 is usually known as the Schotten-Baumann method, and seldom fails to give good results. The substance is well shaken with sodium hydroxide solution (10$) and benzoyl chloride in excess until the smell of the latter is no longer noticeable. 4 If the benzoylation is to be as complete as possible more concentrated alkali should be used, say fifty parts of soda (20$) and six parts of the chloride in a closed flask. 5 The tempera- ture should not exceed 25 , 6 and it is frequently de- sirable to add the alkali and chloride alternately little by little, whilst in some cases the former must be highly 1 Danckwortt, Arch. Pharm. 228, 581. 3 Lossen, Ann. 161, 348; 175, 274, 319; 205, 282; 217, 16; 265, 148, foot-note. 3 Baumann, B. 19, 3218. 4 Baumann. 5 Panormow, B. 24, R. 971. 6 v. Pechmann, Ibid. 25, 1045. DETERMINATION OF IIYDROXYL. 1 9 dilute. 1 It has also been found to be advisable to use the reagents in the proportion of seven molecules of soda and five of the chloride to each hydro xyl;' the alkali is dissolved in water (8-10 parts), and the shaking and gentle cooling continued during 10-15 minutes. For experiments with pyragallol the flask must be filled with coal-gas ; in the case of similar substances which are so unstable in presence of caustic alkali, sodium carbonate," bicarbonate, or sodium acetate may be used. 4 The precipitated benzoyl deriv- atives are usually white and semi-solid, and gradually harden and crystallize by prolonged contact with water ; often traces of benzoyl chloride or benzoic acid are retained with great tenacity. For the purification of the benzoyl derivative of dextrose B it was necessary to dissolve out the crude product with ether; this was distilled off, and the residue treated with alcohol, which decomposed the last portions of benzoyl chlo- ride that had not been removed by prolonged shaking of the ethereal solution with concentrated alkali. The alcoholic liquid was treated with soda in excess, pre cipitated with water, and the alcohol and ethylic ben- zoate removed by means of steam. The residue was then repeatedly recrystallized ; at first from alcohol, then from glacial acetic acid. The pure compound is insoluble in ether, whilst the crude preparation readily dissolves. Benzoic acid may be frequently removed by sublimation in vacuo, or by extraction with boiling 1 B. 31, 1598. 2 Skraup, M. 10, 390. 1 Lossen, Ann. 265, 148. 4 Bamberger, M. & J., II., p. 546. 6 Skraup, M. 10, 395. 20 RADICLES IN CARBON COMPOUNDS. carbon bisulphide. 1 Repeated extraction with alkali is usually effective for the purification of benzoyl deriv- atives soluble in ether, but it may produce partial hy- drolysis. Commercial benzoyl chloride often contains chlorobenzoyl chloride," and since the chlorobenzoyl derivatives are less soluble than the benzoyl derivatives themselves, recrystallization is not adequate to secure a product free from chlorine. It appears also that pure benzoyl chloride may yield chloro-derivatives. 3 Ben- zotrichloride may contain benzal chloride; during the conversion of the former into benzoyl chloride by the action of lead oxide or zinc oxide the latter may yield benzaldehyde, the presence of which would cause com- plications. 4 Lactones often yield benzoyl derivatives of acids which are soluble in alkali ; they are separated by ao Jifying and removing the benzoic acid from the precipitate by steam distillation. 6 Schotten-Baumann's method has also been applied to the preparation of acetyl derivatives, but with comparatively little success on account of the greater instability of acetyl chloride. 6 (c) Benzoyl derivatives may also be prepared in ethereal or benzene solution, with the help of dry alkali carbonate, 6 or of tertiary bases such as quinoline, pyridine, or dimethyl aniline. 7 (Cf. p. 6.) (d) Sodium ethoxide 8 may also be employed for the decomposition of benzoyl chloride, and it was only in 1 Barth and Schreder, M. 3, 8oo. • V. Meyer, B. 24, 4251. Goldschmiedt, M. 13, 55, foot-note. 3 B. 29, 2057. 4 Hoffmann and V. Meyer, Ibid. 25, 209. 5 Ibid. 30, 127. * Ibid. 27, 3183. 7 L. Claisen, Ibid. 31, 1023. 8 L. Claisen. DETERMINATION OF HYDROXYL. 21 this manner that the benzoyl derivative of diacetyl- acetone could be obtained. 1 The ketone was heated in a reflux apparatus during six hours, with two molec- ular proportions each of benzoyl chloride and sodium ethoxide, which had been dried at 200 ; after cool- ing, the sodium chloride and benzene were removed, the residue dissolved in ether, and the solution shaken with dilute alkali. (e) Pyridine may be used in place of aqueous, or alcoholic alkali. 2 The product is triturated with dilute hydrochloric acid and recrystallized from alcohol. (B) Preparation of Benzoyl Derivatives from Benzoic Anhydride. (a) The hydroxyl compound is heated with benzoic anhydride, in an open vessel, at 150 during 1-2 hours. 3 (b) In some cases the use of benzoic anhydride and sodium benzoate produces a more complete acylation than Schotten-Baumann's method. 4 As an example of its use, scoparin (2 grams), benzoic anhydride (10 grams), and dry sodium benzoate (1 gram) were heated in an oil-bath at 190 during six hours; the product was treated at the ordinary tem- perature overnight with aqueous sodium hydroxide (2$), and the precipitated hexabenzoyl derivative purified by means of alcohol. 1 Feist, B. 28, 1824. * Deninger, Ibid. 28, 1322. 3 Liebermann, Ann. 169, 237. 4 Goldschmiedt and Hemmelmayr, M. 15, 327. 22 RADICLES IN CARBON COMPOUNDS. Not infrequently the addition of sodium benzoate is quite unnecessary. 1 (C) Preparation of Substituted Benzoic Acid Derivatives and of Phenylsulphonic Chloride. (a) Parabromobenzoyl chloride. * — Parabromoben- zoic acid is intimately mixed with the equivalent quantity of phosphorus pentachloride, and warmed until the evolution of hydrogen -chloride slackens. The product is then fractionated under reduced pres- sure ; the pure compound melts at 42 , boils at 174 (102 mm), and is readily soluble in benzene and' light petroleum. (b) Parabromobenzoic anhydride 3 is prepared by heating sodium parabromobenzoate (3 parts) with parabromobenzoyl chloride (2 parts) at 200 during an hour. It melts at 212 , is almost insoluble in ether, carbon bisulphide, and glacial acetic acid, dissolves slightly in benzene, and is purified by recrystallization from chloroform. (c) Orthobromobenzoyl chloride* is prepared in a similar manner to its isomer. It is a liquid, boiling at 24i°-243°, and may be distilled under the ordinary pressure without decomposition. (d) Metanitrobenzoyl chloride b is formed from the nitrobenzoic acid by gradually and intimately mixing with it the requisite amount of phosphorus penta- 1 Arch. Pharm. 235, 313. 2 B. 21, 2244. 3 Schotten and Schlomann, Ibid. 24, 3689. 4 B. 21, 2244. Schopf, Ibid. 23, 3436. 6 Claisen and Thompson, Ibid. 12, ic)43- DETERMINATION OF HYDROXYL. 23 chloride; the phosphorus oxychloride is removed by distillation, and the residue fractionated under re- duced pressure. It melts at 34 and boils at 183 - 184 (50-55 mm). (e) Phenylsulphonic chloride 1 is obtained by heating sodium phenylsulphonate with phosphorus penta- chloride in equivalent proportions ; when the action ceases the product is poured into water, the oily portion removed, washed with water, dissolved in ether, and the solution decolorized by treatment with animal charcoal. The compound melts at 14 and boils at 120 (10 mm). (D) Acylation by Means of Substituted Benzoic Acid Derivatives and of Phenylsulphonic Chlorides. (a) Parabromobenzoyl chloride, or parabromobenzoic anyhdride, has been used for acylation, the number of the original hydroxyl groups, being determined from the bromine content of the product. 3 (b) Ortliobromobenzoyl chloride* and metanitroben- zoyl chloride 4 are also well adapted for the determi- nation of hydroxyl groups. (c) Phenylsulphonic chloride has been employed for 1 Otto, Z. f. Ch. 1866, 106. 8 F. Loring Jackson and G. W. Rolfe, Am. Chem. Journ. 9, 82; B. 20; R. 524. 3 Schotten, Ibidf-21, 2250. 4 Claisen and Thompson, Ibid. 12, 1943. Schotten, Ibid. 21, 2244. 6 Hlnsberg, B. 23, 2962. Schotten and Schlomann, Ibid. 24, 3689. 24 RADICLES IN CARBON COMPOUNDS. the same purpose; it is either allowed to act like the benzoyl chloride in the Schotten-Baumann method, or it is warmed with the hydroxyl compound (phenol) and zinc dust, or zinc chloride. 1 Phenylsulphonic derivatives are often more stable than the corresponding benzoyl compounds. 4 (2) ANALYSIS OF BENZOYL DERIVATIVES. (a) The exact number of benzoyl groups in many benzoyl derivatives is shown by their elementary analysis; in substitution products the amount of haloid, nitrogen, or sulphur is determined. (b) The following method has been suggested for the direct determination of. the benzoic acid: 3 The substance (about 0.5 gram) is hydrolysed by heating it during two hours at ioo°, in a sealed tube, with concentrated hydrochloric acid (10 parts), which has been saturated with benzoic acid at the ordinary temperature. The product is allowed to remain 1-2 days at the ordinary temperature, filtered by means of the pump, and the precipitate washed, at first with more of the hydrochloric acid, then with a saturated aqueous solution of benzoic acid. The purified benzoic acid is now dissolved in N/10 so- dium hydroxide solution in excess, titrated with excess of acid, and the neutralization effected with the needful quantity of the soda solution. The latter is standardized against pure benzoic acid, 1 C. Schiaparelli, Gazz. 11, 65. 2 B. 30, 669. 3 G. Pum, M. 12, 438. DETERMINATION OF HYDROXYL. 2$ phenolphthalein being employed as the indicator. The admixture of the acid and water during the washing of the benzoic acid always causes a precipi- tation of benzoic acid, so that the results obtained by this method are invariably about I per cent, too high; therefore, this amount must be deducted from the percentage of acid found, or the exact cor- rection ascertained by means of a blank experiment with the same quantities of liquids as have been used in the main one. (c) A method of more general application consists in separating the benzoic acid from the hydrolysed substance by means of a current of steam, and ti- trating the distillate; 1 its principle is therefore identical with the determination of acetyl groups, and it presupposes that the compound under exam- ination is completely hydrolysed by alkalis, and yields no acid other than benzoic, volatile with steam. The substance (about 0.5 gram) is mixed with alcohol (30-50 cc) and potassium hydroxide in excess, and heated in a reflex apparatus ; when the hydroylsis is completed the product is cooled, acidified with concentrated phosphoric acid solution or vitreous phosphoric acid, and distilled in a cur- rent of steam. The distillation is conducted slowly at first, and alcohol added, if necessary, by means of a dropping funnel, the object being to secure the gradual deposition, in a crystalline state, of the hydrolysis products as otherwise resinous substances might surround the benzoic acid and considerably 1 R. and H. Meyer, B. 28, 2965. 26 RADICLES IN CARBON COMPOUNDS. hinder its volatilization. When the distillate meas- ures 1-1.5 liters, the following 150 cc are collected separately and tested for benzoic acid by titration, and, as soon as it is no longer present, the distillation is stopped. The combined distillate is rendered al- kaline with a known quantity of N/10 sodium hydrate solution, standardized against pure benzoic acid, and evaporated in a platinum, silver, or nickel dish to a volume of 100— 150 cc, when the excess of alkali is titrated back, the liquid being boiled to expel carbonic anhydride; this may be regarded as ac- complished when boiling during ten minutes produces no change in the indicator, which is aurin or rosolic acid. In order to guard against the production of sulphites and sulphates, the concentration of the alkaline liquid is carried out by means of a spirit or petroleum lamp, unless a special gas burner is available. (d) Benzoylmorphine has been examined by direct titration. 1 The substance was dissolved m methylic alcohol, mixed with a little water, normal sodium hy- drate solution (100 cc) added, and boiled in a reflux apparatus until a portion of it gave no turbidity with water; titration with normal hydrochloric acid, in presence of phenolphthalein, showed that the original compound was the monobenzoyl derivative. The same method was successfully applied to the analysis of dibenzoylpseudomorphine and tribenzoyl- meythlpseudomorphine. 1 Vongerichten, Ann. 294, 215. Cf. Knorr, B. 30, 917-920. DETERMINATION OF HYDROXY!* 27 ACYLATION BY MEANS OF OTHER ACID RADICLES. Propionic anhydride, isobutyric anhydride, opianic acid, 1 stearic anhydride, 2 and phenylacetyl chloride are sometimes used for acylation, as their relatively high boiling points facilitate their reaction with the hydroxyl compound. (a) Propionyl derivatives are prepared by heating the substance with propionic anhydride, in a stout, closed bottle, at ioo° during two hours; an open vessel may also be employed, and the reaction started by the addition of a drop of concentrated sulphuric acid.' {b) Isobutyryl derivatives are prepared in a similar manner. Isobutyryl ostruthin was prepared by heat- ing ostruthin (3 grams) with isobutyric anhydride (10 grams) in a sealed tube at 150 during 3 hours. The product was poured into water, allowed to re- main until it became crystalline, washed with warm water until neutral, pressed, dried by means of filter paper, and recrystallized from alcohol.* (c) Phenylacetyl chloride is not difficult to prepare, 5 and is used e like benzoyl chloride in Schotten-Bau- mann's method, the substance being dissolved in di- lute aqueous potassium hydroxide solution, and well shaken with excess of the chloride. (d) The extent to which phosphoric acid may prove useful remains at present undetermined. 7 1 B. 31, 358. 3 Ann. 262, 5. 3 Arch. Pharm. 228, 127. 4 Jassoy, Arch. Pharm. 228, 551. B B. 20, 1389; 29, 1986. « Hinsberg, Ibid. 23, 2962. T Ibid. 30, 2368; 31, 1094. 28 RADICLES IN CARBON COMPOUNDS. II. ALKYLATION OF HYDROXYL GROUPS. The hydroxyl of phenol and primary alcohols is capable of alkylation, and the number of alkyl groups introduced may be determined from the resulting ethers by Zeisel's method (cf. p. 33). As a rule, the phenolic ethers are not hydrolysed by alkalies (cf. p. 457), hence it is possible to differentiate between the hydroxyl and carboxyl of the hydroxy acids. It has, however, been shown that the use of potassium hydroxide and alkyl iodides may lead to the production of compounds with the alkyl directly linked to carbon, 2 and that, on the other hand, hydroxyl in the ortho-position relative to carbonyl oxygen is determinable by acy- lation, but not by alkylation. 3 Diazomethane may also be used as an alkylating agent. 4 PREPARATION OF BENZYL DERIVATIVES. Benzyl ethers of phenols are prepared by heating the latter in a reflux apparatus, during several hours, with the calculated quantities of sodium ethoxide and benzyl chloride in alcoholic solution, the pre- cipitated sodium chloride is removed by filtration from the hot liquid, 6 and the composition of the 1 B. 30, 2368; 31, 1094. s Herzig and Zeisel, M. 9, 217, 882; 10, 144, 735; 11, 291, 311, 413; 14, 376. 3 Graebe. Herzig, M. 6, 72, Schunk and Marchlewsky, Journ. Chem. Soc. 65, 185. Kostanecki, B. 26, 71, 2901. Perkin, Journ. Chem. Soc. 67, 995; 69, 801. 4 v. Pechmann, B. 28, 856; 31, 64, 501, Ch. Ztg. 98, 142. 6 Haller and Guyot, C. r. 116, 43. DETERMINATION OF HYDROXYL. 29 ether determined by elementary analysis. Benzyl iodide may also be employed for the preparation of these compounds. 1 III. PREPARATION OF CARBAMATES BY MEANS OF CARBAMYL CHLORIDE. PREPARATION OF CARBAMYL CHLORIDE. 3 Ammonium chloride is placed in a distillation flask attached to a long and wide condenser, heated at about 400 in an air bath, and treated with a cur- rent of carbonyl chloride, dried by means of sul- phuric acid. The carbamyl chloride, which has a highly offensive smell, distils over and condenses to a colorless liquid, or to long, broad needles melting at 50 . It volatilizes at 6i°-62°, and, after prolonged standing, polymerizes to cyamelide, for which reason it should be employed as quickly as possible after its preparation. In contact with water or moist air, it is hydrolysed to carbonic anhydride and ammonium chloride. PREPARATION OF CARBAMATES. Carbamyl chloride reacts with hydroxyl derivatives in accordance with the equation : NH, CO. CI + HO.R ^ NH,.CO.OR + HC1, the resulting carbamates readily crystallize. 3 It is >*M. & J. II., p. 125. 2 Gattermann & G. Schmidt, B. 20, 858. 5 Gattermann, Ann. 244, 38. 30 RADICLES IN CARBON COMPOUNDS. usually only necessary to mix the substances in equivalent proportion in ethereal solution as the re- action generally proceeds quantitatively at the ordinary temperature ; in the case of some polybasic phenols gentle warming is requisite. The amount of nitro- gen in the product is a measure of the number of hydoxyl groups in the original compound. Great excess of the chloride should not be used, as it may lead to the production of ethereal allophanates, NH 2 .CO.NH.CO.OR. IV. PREPARATION OF DIPHENYLCAR- BAMYL CHLORIDE (C.H.), N.CO CI. This substance has been found especially useful in the investigation of rhodinol (geraniol). 1 It is prepared by dissolving diphenylamine (250 grams) in chloroform (700 cc), adding anhydrous pyridine (120 cc), and passing a current of carbonyl chloride (147 grams) into the liquid, which is main- tained at o°. After remaining during 5-6 hours, the chloroform is distilled off on the water-bath, and the residue crystallized from alcohol (1.5 liters). The yield is 300 grams, the product, after recrys- tallization from alcohol (1 liter), is pure, and melts at 84V 1 Erdmann and Huth, J. pr. 53, 45. 2 Ibid. 56, 7 DETERMINATION OF HYDROXYL. 3 1 V. PREPARATION OF PHENYLCARBAMIC ACID DERIVATIVES. PREPARATION OF PHENYLISOCYANATE. 1 Commercial phenylurethane (15 grams) is mixed with phosphoric anhydride (30 grams) in a small retort, and heated by means of a luminous flame, a large distillation flask being employed as receiver; the combined distillate from a number of such prep- arations is then fractionated once. The isocyanate boils at 169 (769 mm), 3 and the yield is 52-53 per cent. 8 ACTION OF PHENYLISOCYANATE ON HYDROXYL DERIVATIVES. 4 Ethereal phenylcarbamates are formed by the inter- action of hydroxyl compounds and phenylisocyanate in equimolecular proportion in accordance with the equation : R.HO + C 6 H 6 N : CO ** C 6 H 6 NH.CO.OR. The reaction often proceeds at the ordinary tempera- ture, but it is best to rapidly boil the compounds, mixed in the requisite proportion, by means of a previously heated sand-bath, and complete the reaction by shaking and gentle warmth. 6 Polybasic phenols are 1 H. Goldschmiedt, B. 25, 2578, foot-note. 8 Hofmann, B. 18, 764. a Zanoli, Ibid. 25, 2578, foot-note. 4 Hofmann, Ann. 74, 3; B. 18, 518. Snape, Ibid. 18, 2428. 5 Tessmer, Ibid. 18, 969. 32 RADICLES IN CARBON COMPOUNDS. heated in a sealed tube during 10-16 hours; 1 if the compound eliminates water at this temperature the phenylisocyanate is converted by it into carbonic an- hydride and carbanilide. 2 The duration of the boil- ing in an open vessel should be shortened as much as possible to reduce the production of diphenylcar- bamide. When cold the product of the reaction is treated with a little benzene or ether to dissolve un- altered phenylisocyanate, then, after the removal of the benzene or ether, washed with cold water and recrystallized from alcohol, ethylic acetate, or a mixture of ether and light petroleum, which leaves the sparingly soluble diphenylcarbamide undissolved. The presence of negative groups in the molecule of the hydroxyl derivative hinders or completely pre- vents the reaction ; thus trinitrophenol gives no deriv- ative when heated at 180 under pressure. 3 An attempt has been made to determine the presence of hydroxyl groups by the use of 1 :2 -.4- chlordinitrobenzene. * 1 Snape, B. 18, 2428. 8 Tessmer, Ibid. 18, 969. Beckmann, Ann. 292, 16. "Gumpert, J. pr. 31, 119; 32, 278. 4 Vongerichten, Ann. 294, 215. Chapter IT. DETERMINATION OF METHOXYL. CH 3 6-, ETHOXYL, C a H 5 6- AND CARBOXYL, CO.OH. I. DETERMINATION OF METHOXYL, CH 3 6-. S. ZEISEL'S METHOD. 1 This method, which is distinguished for beauty and reliability, depends on the conversion of the methyl of the methoxy group into methyl iodide by means of hydriodic acid, the methyl iodide being then decomposed by alcoholic silver nitrate solution into silver iodide. The original apparatus, repre- sented in Fig. I, consists of a reversed condenser K, through which water at 40°-50° flows ; at the lower end a flask A of 30-35 cc capacity is attached by means of a cork ; the flask has a side tube sealed on through which a current of carbonic anhydride may be passed. A Geissler's potash bulb is connected to the upper end of the condenser, also by means of a cork; it contains 0.25-0.5 gram red phosphorus suspended in water,** and is maintained at a tem- perature of 50°-6o° by the water-bath in which it is placed. Its object is to absorb any iodine or hydriodic acid which might be carried over by the 1 M. 6, 989 ; 7, 406. 33 34 RADICLES IN CARBON COMPOUNDS. methyl iodide vapor. The two flasks which complete the apparatus have a capacity of 80 cc each, the first contains 50 cc of alcoholic silver nitrate solution, the second 25 cc; they are connected by means of METHOXYL, ETIIOXYL, AND CARBOXYL. 35 corks, and may be conveniently replaced by two dis- tillation flasks, the side tube of the first being bent downwards at a right angle into the second. A modi- fied apparatus has been described, which serves as a combined condenser and washing arrangement, 1 and also a second one, which has in addition a very con- venient appliance for heating and supplying the water to the condenser. 2 Modified boiling flasks,* (Fig. 2), which prevent the action of the heated hydriodic acid on the cork, have been designed. If Jt* the substance under examination is not vola- \sf tile, the condenser may be replaced by a vertical tube bent back in a U shape. The method is not applicable to compounds con- s v taining sulphur, and the hydriodic acid em- ( ) ployed must not have been prepared by F , means of hydrogen sulphide, otherwise it is difficult to completely free it from volatile sulphur compounds, the presence of which would be apt to cause the formation of mercaptanes and silver sulphide. C. A. F. Kahlbaum, of Berlin, supplies "hydriodic acid for methoxyl determination," which is prepared by means of phosphorus, and is trust- worthy. Should a blank experiment show that the hydriodic acid produces a perceptible precipitate in the silver nitrate solution, it must be purified by dis- tillation, the first and last quarters of the distillate being rejected; it should have a sp. gr. — 1. 68-1. 72. Boiling the acid with a reversed condenser, even 1 Benedikt and Griissner, Ch. Ztg. 13, 872. 1 L. Ehmann, Ibid. 14, 1767; 15, 221. 3 Benedikt, Ibid. 13, 872. M. Bamberger, M. 15, 505. $6 RADICLES IN CARBON COMPOUNDS. during several days, 1 does not suffice for its purifica- tion. The silver nitrate solution is prepared by dis- solving the fused salt (2 parts) in water (5 parts) and adding absolute alcohol (45 parts!); it is kept in the dark, and the quantity required for each determina- tion filtered into the absorption flasks. I. METHOD FOR NON- VOLATILE SUBSTANCES. After the apparatus is put together, tested, and found to be air-tight, the silver nitrate solution is introduced into the absorption flasks, and the sub- stance (0.2-0.3 g ram )> together with the hydriodic acid (10 cc), placed in the distillation flask; unless Bamberger's pattern is employed this should also contain a few pieces of porous plate to regulate the ebullition ; it is then heated to boiling in a glycerine- bath. During this time the current of carbonic anhy- dride is passed through the apparatus at the rate of three bubbles in two seconds. The gas employed must be washed with water, and also with silver nitrate solution, to remove any hydrogen sulphide arising from impurities in the marble. The warm water must also be supplied to the condenser and the bath containing the potash bulbs. Some 10-15 min- utes after the acid begins to boil the silver nitrate becomes turbid and soon a white double compound of silver nitrate and silver iodide precipitates in the first flask; the liquid in the second one usually remains clear, but sometimes becomes opalescent if the current of carbonic anhydide is very rapid or the substance 1 Benedikt. METHOXYL, ETHOXYL, AND CARBOXYL. 37 particularly rich in methoxyl groups, these conditions may also cause the precipitate to become yellow. The conclusion o*f the experiment is readily indicated by the complete subsidence of the precipitate, which becomes crystalline; the time required is 1-2 hours. The tubes and flasks with the silver solution are disconnected, and the second one diluted with five parts of water; if no precipitate appears after remaining several minutes nothing more is done to it, otherwise it is added to the contents of the first flask, which are poured into a beaker, any precipitate adhering to the tubes is removed to the beaker by means of a feather and jet of water; the volume is now made up to about 500 cc with water, evaporated to one half on the water-bath, then water and a drop of nitric acid added, and the liquid digested until the silver iodide is completely precipitated; it is then filtered and weighed in the usual manner. The precipitate adher- ing to the tubes is usually dark-colored, possibly from the presence of a trace of phosphorus, "but this does not affect the accuracy of the determination. 100 parts of silver iodide = 13.20 parts of CH 3 = 6.38 parts of CH S . The method is applicable to com- pounds containing chlorine, bromine, 1 or nitro-groups, but not to sulphur compounds. 2 In the case of nitro-derivatives, or other compounds which readily liberate iodine from hydriodic acid, it is desirable to place a little red phosphorus in the boiling-flask. The potash bulbs require refilling after four or five determinations. Hydriodic acid causes many sub- 1 G. Pum, M. 14, 498. 5 Zeisel. Ibid. 7, 409. Benedikt and Bamberger, Ibid. 12, 1. 38 RADICLES IN CARBON COMPOUNDS. stances to become resinous, and the resin may protect a portion of the methoxy compound from the action of the acid. This difficulty may be overcome by adding to the acid acetic anhydride (6-8 volumes per cent), as was shown in the case of methyl and acetylethyl- quercetin, rhamnetin, and triethoxyphloroglucinol. 1 The method is also well adapted for the determination of alcohol of crystallization. 2 2. MODIFICATIONS OF THE METHOD FOR ITS USE WITH VOLATILE COMPOUNDS. Volatile substances may usually be treated in the manner described above if, at the commencement of the experiment, a slow stream of carbonic anhydride is employed and cold water run through the condenser. The following special modifications for particularly volatile compounds have been suggested. 8 The sub- stance (o.i -0.3 gram) is sealed into a small bulb of thin glass, which is sealed up in a larger tube together with hydriodic acid (10 cc, sp. gr. = 1.7) and a piece of heavy glass about 2 cm in length with a sharp corner. The heavy glass is to assist in break- ing the bulb with the substance before the heating, but is unnecessary if the latter is enclosed in test- tube glass with a long capillary. The larger tube is 30—35 cm long and 1.2— 1. 5 cm inner diameter; both ends are drawn out, the one to fit into a tube 10 cm long and 1-2 cm inner diameter, which is 1 Herzig, M. 9, 544. Cf. Pomeranz, Ibid. 12, 383. 8 J. Herzig and H. Meyer, Ibid. 17, 437. 8 Zeisel, Ibid. 7, 406. METHOXYL, ETHOXYL, AND CARBOXYL. 39 sealed to a wider tube, the other so that a piece of stout rubber tube will fit over it quite tightly. The drawn-out ends must be strong enough to resist the pressure during the heating, and sufficiently thin to be readily broken after being scratched with a file. The substance and hydriodic acid are heated at 130 during two hours, then, when cold, one point of the tube is fitted into the narrow one mentioned above, the wide portion of which passes through a triply bored cork into a wide-mouthed flask. Into the second opening of the cork the condenser fits, whilst the third con- tains a piece of stout glass rod bent to a Z form ; by turning this the drawn-out end of the heating-tube is broken. The contents are transferred to the flask partly by shaking, partly by gently warming; the upper capillary is covered with a piece of rubber, the end broken, and a current of carbonic anhydride immediately passed through the apparatus. The determination then proceeds in the manner already described. 3. MODIFICATION OF ZEISEL'S METHOD. 1 Instead of red phosphorus and water the potash bulbs contain a solution consisting of arsenious anhydride (1 part), potassium carbonate (1 part), and water (10 parts). The bulbs must be refilled for each deter- mination to prevent the apparatus becoming choked with precipitated anhydride, but this is compensated for by the fact that not the slightest reduction (black- 1 T- Gregor, M. 19, 116. 40 RADICLES IN CARBON COMPOUNDS. erring) of the silver nitrate solution takes place. The N/io silver nitrate solution is made by dissolving the nitrate (17 grams) in water (30 cc) and diluting to a liter with commercial absolute alcohol, its titer being determined by means of N/10 potassium thiocyanate solution. For the alkyloxyl determination the silver solution (75 cc) is acidified with a few drops of nitric acid, free from nitrous acid, and divided between the two absorption flasks. At the conclusion of the ex- periment the silver solution with the precipitate is di- luted with water to 250 cc, cautiously shaken, filtered by means of a dry ribbed filter into a dry flask, and 50 cc or 100 cc of the clear filtrate acidified with nitric acid, free from nitrous acid, treated with ferric sulphate solution, and titrated in the ordinary manner. 1 METHOD FOR THE DIFFERENTIATION OF METHOXYL AND ETHOXYL. Zeisel's method does not distinguish between meth- oxyl and ethoxyl ; should this be necessary, the alkyl iodide must be prepared in quantity sufficient for its identification, or, if possible, Lieben's iodoform test must be applied. For the differentiation of the alkyls the investigation of the action of phenyl isocyanate on the alkyloxy derivatives has been suggested.* The compound is heated with phenyl isocyanate, in equimolecular proportion, at 150 during several hours in a sealed tube. The product is steam-dis- tilled and the volatile portion purified by recrystal- 1 Volhard, J. pr. 9, 217. Ann. 190, 1. Z. anal. 13, 171; 17,482. 2 Beckmann, Ann. 292, 9, 13. METIIOXYL, ETIIOXYL, AND CARBOXYL. 41 lization from a mixture of ether and light petroleum; methylphenylurethane melts at 47°, ethylphenyl- urethane at 50 , and they can be further distinguished by analysis. DETERMINATION OF ETHOXYL (C 2 H 5 6-). The determination of ethoxyl ' is carried out exactly in the manner described in the preceding section for methoxyl except that the water in the condenser and in the bath surrounding the potash bulbs should be heated at about 8o°. 100 parts of silver iodide = 19.21 parts C 2 H & == 12.34 parts C a H 6 . DETERMINATION OF CARBOXYL (CH.OH). The following methods are employed for the de- termination of the basicity of organic acids: (A) Analysis of metallic salts of the acid. (B) Titration. (C) Etherification. (D) Determination of the electrolytic conductivity of the sodium salts. (E) Indirect methods: (1) Carbonate method. (2) Ammonia method. (3) Hydrogen sulphide method. (4) Iodine method. It is easy to decide which of these methods is the most suitable for any special case, but the qualitative differentiation between carboxyl and phenolic hy- 1 Zeisel, M. 7, 406. 42 RADICLES IN CARBON COMPOUNDS. droxyl frequently presents difficulties that can only be overcome with certainty by the preparation of the amide and its conversion into the nitrile. (A) Determination of Carboxyl by Analysis of Metallic Salts of the Acid. In many cases the number of carboxyl groups in an organic compound may be determined by the analysis of its neutral salts; of these the silver salts are usually the most appropriate, as they are generally formed directly without admixture of hydrogen salts and are almost always anhydrous. Exceptions to this rule are, however, encountered ; thus the silver salts of cantharidinic acid, 1 camphoglycuronic acid, 2 and meta- quinaldinic acid 3 crystallize with one, three and four molecules of water respectively, and hydrogen silver salts, 4 though not of frequent occurrence, are known. Aromatic hydroxymonocarboxylic acids containing two nitro-groups often give salts containing two atoms of silver. As examples may be mentioned 3 :5-dinitro- hydrocumaric, 1 13 : 5-dinitroparahydroxy benzoic and 2 : 6-dinitro-5 -hydroxy- 3 -4-dimethylbenzoic acids. 5 Many silver salts are very sensitive to light or air, and some, like silver oxalate, are explosive ; for the analysis of such the compound is dissolved or sus- pended in water or acid, and treated with hydrogen 1 Homolka, B. 19, 1083. 8 Schmiedeberg and Meyer, Z. physiol. Chem. 3, 433. 3 Eckhardt, B. 22, 276. 4 A list of them is given in Lassar-Cohn " Manual of Organic Chemistry," translated by Alex. Smith, p. 345. 5 W. H. Perkin, Jun., Journ. Chem. Soc. (1899), 75, 176. METHOXYL, ETHOXYL, AND CARBOXYL. 43 sulphide or hydrochloric acid. Silver salts which do not explode when heated are usually analyzed by igni- tion in a porcelain crucible ; if the residual silver con- tains carbon it is dissolved in nitric acid, the solution diluted and filtered, and the silver precipitated by means of hydrochloric acid. Pyridine and quinoline derivatives and amino-acids in particular often give characteristic copper and nickel salts, whilst, in the aliphatic series, the zinc salts may often be usefully employed. Sodium, potassium, cal- cium, barium, magnesium, and, less frequently, leaa salts are also sometimes used for the determination of basicity, but, as many acids do not yield well-defined neutral salts, and groups other than carboxyl can ex- change hydrogen for metal, the method has not a very wide application. (B) Titration of Acids. The basicity of a carboxyl derivative may often be determined by titration if the molecular weight of the compound is known; N/10 sodium hydroxide, potas- sium hydroxide, or barium hydroxide may be used for the titration in aqueous solution, or, in the case of the first two, in alcoholic solution. N/2 ammonium hydroxide has also been employed. 1 The acids used are generally hydrochloric or sulphuric, but the latter is unsuited for work with alcoholic solutions, as the precipitation of insoluble sulphates prevents a correct observation of the end reaction. The liquid, alcohol, ether, etc., in which the compound under examination 1 Haitinger and Lieben, M. 6, 292. 44 RADICLES IN CARBON COMPOUNDS. is dissolved must either be free from acids or must be previously accurately neutralized by means of N/io alkali. Phenolphthaleln, methyl orange, rosolic acid, curcumin, or litmus, are usually employed as indi- cators, the first two more frequently than the others. If the liquid is dark colored the use of " alkali blue" is often convenient, and attention must always be paid to the possible presence of carbonic anhydride. A somewhat curious and interesting attempt has been made to determine the neutrality by taste. 1 (C) Etherification. In very many cases carboxylic and phenolic hydrogen may be differentiated by the etherification of the com- pound with alcohol and hydrogen chloride. It has, however, been shown 3 that acids with the group C.COOH /\ (t and t' = tertiary carbon atom) do not c c t t yield esters with alcohol and hydrogen chloride if both the carbon atoms marked t are linked to CI, P , I, or N0 2 , whilst the groups of smaller mass F, CH 3 , OH in the same positions greatly retard, but do not entirely prevent, etherification. On the other hand, certain phenols such as phloroglucinol," which gives a diether, hydroxyanthracene (anthrol and a- and /3- naphthol * ) yield ethers when treated with hydrogen 1 T. W. Richards, Am. Chem. Journ., 20, 125. 2 V. Meyer and others. Many papers appeared on the subject beginning B. 27, 510, and ending 29, 2569. * Ibid. 17, 2106; 21, 603. 4 Liebermann and Hagen, Ibid. 15, 1427. 45 chloride and alcohol. The etherification is most con- veniently carried out by boiling the substance during 3-5 hours in a reflux apparatus with a large excess of absolute alcohol containing 3-5 per cent of hydrogen chloride or sulphuric acid. 1 Occasionally alcohol of 95 per cent may be employed if more sulphuric acid is used. 2 Some substances form additive compounds with alcohol and hydrogen chloride. 3 This, as also the contamination of the ester by traces of chlorine derivatives, which can only be removed with difficulty, may lead to confusion. The esters obtained by acid or alkaline etherifica- tion are, in general, distinguished from the phenolic ethers by the ease with which aqueous or alcoholic alkalis hydrolyse them, but exceptions are known since trinitromethoxybenzene (methoxy picrate) when boiled with concentrated potassium hydroxide yields methyl alcohol and potassium picrate, 4 and methoxy- anthracene (methyl anthranol) is also decomposed by boiling with alcoholic potash. 6 The composition of the esters is determined by elementary analysis, and the alkyloxy groups by the methods described in the earlier portion of this chapter. 1 E. Fischer and A. Speier, B. 28, 3252. a Bishop Tingle and A. Tingle, Am. Chem. Journ. 21, 243. • Freund, B. 32, 171. 4 Ann. 174, 259. 5 Liebermann and Hagen, B. 15, 1427. 46 RADICLES IN CARBON COMPOUNDS. (D). Determination of the Basicity of Acids by means of the Electrolytic Conductivity of the Sodium Salts. It has been shown that the degree of electrolytic conductivity of the sodium salt is a certain indication of the basicity of the corresponding acid. 1 The method is of very general application, since insoluble acids usually yield sodium salts which dissolve in water, but it fails in the case of acids which are so feeble that their sodium salts are hydrolysed by water sufficiently to impart an alkaline reaction to the solu- tion. The following apparatus is required for the determination : (i) A small induction coil (J, Fig. 5), such as is em- ployed for medicinal purposes, and which requires only one or two cells for prolonged use. The spring of the interrupter must vibrate rapidly so as to produce a high pitched sound in the telephone, as this is more easily heard than a deeper tone. (2) A bridge consisting of a scale 100 cm in length divided into millimeters; along it stretches a wire provided with a sliding contact. The wire is of platinum, German silver, platinoid, or manganin, of which the last is the best on account of its low tem- perature coefficient. The wire must be calibrated. 2 (3) A rheostat for adjusting the resistance (W, Fig- 5)- 1 Ostwald, Z. 2, 901; 1, 74. Valden, Ibid. 1, 529; 2, 49. 8 Strouhal and Barus, Wied. Ann. 10, 326. The method is also described by Jones, ** Freezing-point, Boiling-point, and Con- ductivity Methods," Chem. Pub. Co., 1897. METHOXVL, ETHOXYL, AND CARBOXYL 47 x^r Fig. 3- (4) A resistance cell for the electrolyte (E, Fig. 5). Kohlrausch's form (Fig. 3) is used for low resist- ances whilst that of Arrhenius (Fig. 4) is employed for dilute solution where the re- sistance is high. The electrodes must be platinised by filling the vessel with a dilute solution of hy- droplatinochloric acid Fig. 4. and passing a current of 4-5 volts. The direction of the current is changed occasionally and the electrolysis continued until both electrodes are completely covered with platinum black, which only requires a short time ; the platinum chloride in the cell is now replaced by sodium hydroxide solution, the electrolysis con- tinued for a few moments, the electrodes then thoroughly and carefully washed with hydrochloric acid, and finally with water; the sodium hydroxide removes all chlorine which is otherwise very obsti- nately retained by the platinum. The use of Lummer and Kurlbaum's solution for platinizing is highly recommended, as the tone minima are much more distinct. 1 The solution consists of platinum chloride (1 part), lead acetate (0.008 part), and water (30 parts); it is electrolysed with a current density of O.03 amperes per sq. cm., the direction of the current being frequently changed and continued until each Kohlrausch, Wied. Ann. 1897, p. 315; E. Cohen, Z. 25, 1611. 48 RADICLES IN CARBON COMPOUNDS. electrode has been the cathode during at least fifteen minutes. (5) A telephone. Ostwald states that the most sen- sitive ones are made by Ericsson of Stockholm, but for ordinary purposes a Bell instrument is sufficiently good. In using it the unoccupied ear may be closed with cotton to exclude external sounds. (6) A zvater-batJi with stirrer and thermometer, or a thermostat.* The apparatus is arranged in the form of Kirch- hoff's modification of the Wheatstone bridge (Fig. 5), the connections being made with stout copper wire. The induction coil is enclosed in a sound tight case, or is placed in another room. If determinations of solutions of a substance at different concentrations are to be made the solu- tion is most conveniently prepared in the resistance cell itself, portions are then withdrawn by means of an accurately calibrated pipette, and the desired volume of water added which has previously been brought to the necessary temperature in the thermostat. As a rule the telephone does not give an absolutely sharp minimum at any given point, but it is easy to find two limits beyond either of which the tone rises; these are usually separated by an interval of 0.5—2 mm, and the required position is taken as midway 1 Ostwald, Z. 2, 564, where also a good description of the other parts of the apparatus is given. METHOXYL, ETHOXYL, AND CAKBOXYL. 49 between them. A little experience enables the con- ductivity to be determined with an accuracy of o. 1 per cent. If the tone minimum becomes indistinct the electrodes must be replatinised. The conductivity is calculated from the measurements by means of the formula p. = k . — '— , where w . b jli= the molecular conductivity; v == the volume of the solution in liters which con- tains a gram molecule of the electrolyte ; w = the adjusting resistance; a = the length of wire to the left of the sliding con- tact (Fig. 5); b ss that to the right of the contact (Fig. 5) k = the resistance of the cell. The value of k is determined by measuring the con- ductivity of N/50 solution of potassium chloride, for which Kohlrausch found the values: fx = 112. 2 at 18 . /i — 129.7 at 25 . Other solutions may also be used. 1 The value - a for a wire 1000 mm in length has been calculated by Obach and an abbreviated table of the results is given in the appendix. The conductivity of the water em- ployed, which should be as highly purified from dis- solved substances as possible, is determined in the same manner as that of the solution, the value for 1 Wiedemann and Ebert, Physik. Praktikum, p. 389. $0 RADICLES IN CARBON COMPOUNDS. each liter (v) is calculated according to the formula, and subtracted from the uncorrected value of //. For basicity determinations the conductivity is usually determined at concentrations of one gram molecule in 32 and 1024 liters respectively. The mean difference A between these values is as follows: Monobasic acids Dibasic " Tribasic " Tetrabasic " Pentabasic ' ' . A = 10.4 = 1 x 10.4 . A = 19.0 = 2 x 9-5 . A = 30.2 = 3 x 10. 1 . A = 41. 1 =: 4 x 10.3 . A = 50.1 = 5 X 10 A method has been described ' for determining the basicity of acids based on the alterations which they exhibit in electrolytic conductivity on the addition of alkali. Instead of the telephone and induction coil, a double commutator and a galvanometer may be used to determine the electrolytic conductivity, the commutat- ing apparatus, termed a secohmmeter, is so arranged that one commutator is included in the battery circuit and the other in that of the galvanometer; on rotating the current is reversed in the liquid so frequently that polarization is annulled whilst the galvanometer is commuted." D. Be-thelot, C. r. 112, 287. Cahart and Patterson, " Electrical Measurements," p. 109. METHOXYL, ETHOXYL, AND CARliOXYL. 5 1 (E) Indirect Methods for the Determination of the Basicity of Acids. These methods may be divided into four classes according to the nature of the substance liberated by the acid : (i) Carbonate method. (2) Ammonia method. (3) Hydrogen sulphide method. (4) Iodine-oxygen method. (1) Carbonate Method. — The substance (0.5— 1 gram) is dissolved in water in a flask closed by a rubber stopper with three holes. In one hole a condensing tube is fitted, which, at the lower end, is flush with the stopper whilst the upper end is connected with an absorption apparatus consisting of two calcium chloride tubes and potash bulbs. Through the second hole a tube passes to the bottom of the flask, the end being drawn out and bent upwards; by means of this tube a current of air, free from carbonic anhydride, is passed. The third hole of the flask is closed with a small dropping funnel, the end of which is also drawn out and bent upwards and dips below the liquid in the flask. The solution of the acid is gently boiled, and barium carbonate, in the form of a thin paste, is added in small quantities by means of the funnel. When the operation is completed the apparatus is allowed to cool in a current of purified air, again boiled, cooled, and the absorption bulbs weighed. 1 A similar method, 1 Goldschmiedt and Hemmelmayr, M. 14, 210. 52 RADICLES IN CARBON COMPOUNDS. based on the decomposition of sodium hydrogen car- bonate, has also been described. 1 (2) Ammonia Method, The acid (about 1 gram) is dissolved in excess of alcoholic potassium hydroxide, and made up to 250 cc with alcohol of the same strength (93 per cent). The excess of alkali is neutralized by carbonic anhydride, the precipitated carbonate and bicarbonate filtered off and washed with 50 cc of alcohol (98 per cent). The alcohol is removed from the filtrate and washings by distillation, and the re- sidue boiled with 100 cc of ammonium chloride solution (10 per cent). The potassium salt of the acid decomposes the ammonium chloride, and the liberated ammonia is determined in the usual manner. The amount of alkali carbonate dissolved by 100 cc of alcohol (93 per cent) is equivalent to 0.34 cc of normal acid ; a correction for this must be applied and also one for the ammonium chloride hydrolised by the water; this is determined by a blank experi- ment, 100 cc of the solution being boiled during the same length of time, 1-2 hours, as in the actual deter- mination. 2 The method gives good results with the feebler fatty acids, and is especially useful when the dark color of the solution prevents direct titration. (3) Hydrogen Sulphide Method.* Compounds contain- ing carboxyl liberate hydrogen sulphide from certain metallo-hydrogen sulphides when allowed to react in 1 Vohl B. 10, 1807. C Jehn, Ibid. 10, 2108. 2 P. C. Mcllhiney, J. Am. 16, 408. 8 F. Fuchs, M. 9, 1132, 1143 ; 11, 363. METIIOXYL, ETHOXYL, AND CARBOXYL. 53 an atmosphere of hydrogen sulphide, according to the equation : NaSH + R . COOH + xH 5 S »-> RCOONa- + H 2 S + xH a S two volumes of hydrogen sulphide being liberated for each volume of hydrogen, replaceable by metal, in the original compound. Hydroxyl hydrogen in phenols, alcohols, and hydroxy-acids does not react with the metallo-hydrogen sulphides. Preparation of the Solution. The, majority of alkali salts are sparingly soluble in solutions of the hydrosulphides, hence the solution of the latter must not be so concentrated as to hinder the reaction from being rapidly completed. Potassium hydroxide solution, not exceeding 10 per cent, is boiled with baryta water in excess, the flask closed, and the liquid allowed to cool and deposit barium carbonate. The clear solution is now poured into the vessel to be used for the analysis, and saturated with hydrogen sulphide. Method of Analysis. The evolved hydrogen sulphide may be determined ; (a) volume frically; (b) by titration. The former method is the easier and is therefore generally employed. 54 RADICLES IN CARBON COMPOUNDS. {a) Volumetric Determination. This method is based on the same principle as Victor Meyer's vapor density determination. The apparatus, Fig. 6, consists of a long-necked flask A, made of thick glass; it is fitted with a rubber stoppers through which the deliv- ery tube B pass- es, this is wide at one end but terminates in a capillary at the other. The sec- ond hole of the stopper is closed by means of a Fig. 6. glass rod from which the vessel containing the substance is suspended. Previous to the determination the greater portion of the flask is filled with hydrogen sulphide, but the upper portion of the neck and the delivery tube con- tain, air which is expelled by the evolved hydrogen sulphide and collected over water in a graduated tube. The substance under examination is dried, finely powdered, and about 0.5 gram weighed into the small vessel, the glass rod being pressed into the rubber stopper as far as the mark 1, the vessel fitted on to it by means of the stopper, which, with the delivery tube, is passed air-tight into the flask. The apparatus is allowed to remain for a few moments to equalize the METIIOXYL, ETHOXYL, AND CARBOXYL. 55 temperature, then the capillary end of the delivery- tube is dipped into water below the open end of the gas-measuring vessel, and the vessel with the substance dropped into the sulphide solution by pushing in the rod to the mark 2, care being taken not to alter the position of the stopper itself. The evolution of hy- drogen sulphide ceases after a few minutes. The same solution may be employed for a second or third determination, but each time the delivery-tube must be previously filled with dry air. The weight of car- boxyl hydrogen G is calculated from the results by the formula: V{b-W) 760(1 -f- 0.00366/) V.(b -w). 0.00000005895 .0.0000896 1 -f- 0.00366/ where F= the observed volume of air displaced in cc, b = the height of the barometer, and w the ten- sion of aqueous vapor at the observed temperature t. (b) Titration MetJwd. The apparatus employed consists of a short-necked flask A, Fig. 7, fitted with a rubber stopper and glass rod exactly as used in the preceding method, but the delivery-tube is short in order to expedite the expulsion of air. Before the stopper, with the substance adjusted in the manner described above, is in- serted into the flask, tartaric Fig. 7- 56 RADICLES IN CARBON COMPOUNDS. acid or oxalic acid (about 0.25 gram) is dropped into the potassium hydrogen sulphide solution and the stopper immediately inserted air-tight as shown. As soon as the solution of gas ceases the beaker repre- sented in the figure is replaced by a smaller one contain- ing concentrated potassium hydroxide solution. Some of this rises in the tube on account of the absorption of the gas, but the error so introduced compensates itself at the end of the experiment. As soon as the beaker of alkali has been put into position, the sub- stance is dropped into the sulphide solution with the same precautions as observed in the preceding method; after the cession of the gas evolution, which contimes during 1-5 minutes, the pressure is adjusted by lowering the beaker, the contents are poured into a large flask, and the beaker and evolution tube washed. The alkali and washings are diluted to about 500 cc, neutralized with acetic acid, and titrated with iodine solution in presence of starch. Since H = H 2 S = I 2 , the iodine required, divided by 2 X 126.5, gives the weight of the replaceable hydrogen. The error due to the insertion of the glass rod from mark 1 to 2 may be determined by means of a blank experiment, but it is so small as to be usually negligible. More recently the action of substituted phenols, etc., on alkali hy- drogen sulphides has been investigated 1 with the following results: (1) Haloid substituted phenols with one hydroxyl 1 Fuchs, M. 11, 363. METHOXYL, ETHOXYL, AND CARBOXYL. $? group are without action on the sulphides, but if two hydroxyl groups are present one reacts. (2) Only the paramononitro- phenols react. (3) Under certain conditions the presence of carboxyl groups causes the phenolic hydroxyl to decompose the sulphides. (4) In general lactones do not react, but lactone-acids may suffer partial resolution. 1 With the above exceptions the method provides a ready means of differentiating carboxylic hydrogen from phenolic or alcoholic, a distinction which the two preceding methods do not furnish with certainty. (4) Iodine-oxygen Method.' 1 This depends on the fact that even feeble organic acids liberate iodine from potassium iodide and potassium iodate in accordance with the equation : 6R.COOH+5KI + KI0 3 ^6R.COOK+3l 9 +3H a O. The liberate diodine, in presence of alkali, evolves oxygen from hydrogen peroxide : I a _|_ 2KOH »-> KOI + KI + H a O and KOI + H 2 0, ^ KI + Hfi + O a . The oxygen may be measured in a modified Wagner & Knop's Azotometer, 3 or in any other convenient vessel. The apparatus consists of an evolution flask, with a small cylinder of about 20 cc capacity fused to the middle of the bottom inside, and a large glass cylinder 1 H. Meyer, M. 19, 715. 8 Baumann and Kux, Z. Anal. Ch. 32, 129. 3 Ibid. 13, 389. 58 RADICLES IN CARBON COMPOUNDS. with two communicating burettes and a thermometer fastened to the interior of the cover. The cylinder and burettes are filled with water, the latter by con- necting them with a flask from which water is forced by air pressure from a hand blower, the connecting tube being provided, if needful, with a stop-cock. The evolution flask is closed by means of a rubber stopper carrying a tube with a stop-cock which is connected with the graduated burette • below the stop-cock in which the latter terminates, and which is used for ad- justing the pressure. The temperature of the evolution flask is equalized before and after the determination by placing it in water of the same temperature as that in the large cylinder enclosing the burettes. The following reagents are required : (i) Potassium iodide ) ,i t . . , . > Absolutely free from acid. (2) " lodate ) J (3) Hydrogen peroxide 2-3 per cent, solution. (4) Aqueous potassium hydroxide solution (1 : 1). (5) Distilled water, recently boiled and free from carbonic anhydride. The determination is carried out in the following manner: The acid (o. 1-0.2 gram) is mixed with finely divided potassium iodate (about 0.2 gram), potassium iodide (2 grams), and water (40 cc) in a bottle provided with a well-fitting stopper, and allowed to remain at the ordinary temperature during twelve hours, or at 70°-8o° during a half hour, until the iodine is com- pletely precipitated. The solution is now transferred to the outer portion of the evolution flask, the bottle being washed with not more than 10 cc water. Into METHOXYL, ETHOXYL, AND CARBOXYL. 59 the inner cylinder of the evolution flask is poured by means of a funnel a mixture consisting of hydrogen peroxide (2 cc) and potash solution (4cc), made imme- diately before use and cooled to the ordinary tem- perature. The evolution flask is now closed with its stopper and allowed to stand in water during ten minutes, the stopcock of the burette being opened to equalize the pressure; at the end of this time it is closed, the level adjusted to the zero mark, and if after five minutes no change takes place the experiment is proceeded with, otherwise the cooling is continued dur- ing another five minutes. When equilibrium is established 30-40 cc of water are run from the burette in order to reduce the pressure, the evolution flask is removed from the cooling vessel by means of a cloth and rotated so that the liquids at first circulate with- out mixing and are then suddenly brought into contact. The shaking is continued vigorously for a short time and the flask then returned to the cooling vessel. The evolution of oxygen begins at once, and is completed in a few seconds ; after about ten minutes the pressure in the two burettes is adjusted and the volume read the number of cc of gas, multiplied by the value in the table ' in the appendix corresponding to the pressure and temperature, gives directly the weight of carboxylic hydrogen. An iodometric method for the determination of acids has also been described, for details the original paper should be consulted. 3 1 Baumann, Z. f. ang. Ch. i8qi, p. 328 9 M. Groger, Ibid. 1890, pp. 353, 385. Chapter III. DETERMINATION OF CARBONYL (CO). The presence of the carbonyl group in aldehydes ketones, etc., is recognized by the preparation of derivatives of the following compounds: (i) Phenylhydrazine. (2) Hydroxylamine. (3) Semicarbazide. (4) Amidoguanidine. (5) Paramidodimethylaniline. (i) CARBONYL DETERMINATION BY MEANS OF PHENYLHYDRAZINE. The method is divisible as follows : (A) Preparation of phenylhydrazones from phenyl- hydrazine. (B) Preparation of substituted hydrazones. (C) Indirect method. (A) Preparation of Phenylhydrazones. 1 Carbonyl compounds combine with phenylhydrazine forming water and phenylhydrazones, C 6 H 5 NH.N:CRR i; dihydrazones, with the hydrazine groups linked to neighboring carbon atoms, are termed osazones. The reaction usually takes place most readily in dilute acetic 1 E. Fischer, B. 16, 661, 2241, foot-note ; 17, 572 ; 22, 90. 60 DETERMINATION OF CARBONYL. 6l acid solution, often at the ordinary temperature, almost always by heating on the water-bath. Frequent- ly it is advisable to allow the reaction to proceed at the ordinary temperature in presence of concentrated acetic acid, which acts as a dehydrating agent and in which the phenylhydrazones, as a class, are sparingly soluble. 1 E. Fischer dissolves or suspends the sub- stance in water or alcohol, and adds, in excess, a mixture of phenylhydrazine hydrochloride (i part) and crystallized sodium acetate (1.5 parts) dissolved in water (8—10 parts). Free mineral acids must be neutral- ized by means of sodium hydroxide or sodium car- bonate, as their presence hinders the reaction ; the presence of nitrous acid is particularly hurtful and it must be removed by means of carbamide, as otherwise it reacts with the phenylhydrazine and forms diazo- benzene imide and other oily products. Confusion may also be caused by the production of acetylphenyl- hydrazine from the dilute acetic acid. 9 The phenylhydrazones gradually separate from the solution of their components in an oily or crystalline form, and, in the latter case, are purified by recrystal- lization from water, alcohol, or benzene. It is often desirable to heat the compound under investigation with free phenyhydrazine, and increased pressure may be used if there is no danger of phenyl- hydrazides being formed. 3 The product is poured into water, the phenylhydrazone removed by filtration, washed with dilute hydrochloric acid to free it from excess of phenylhydrazine, and recrystallized ; in some 1 Overton, B. 26, 20. 2 Anderlini, Ibid. 24, 1993, foot-note. 3 M. 14, 395. 62 RADICLES IN CARBON COMPOUNDS. cases glycerol is employed for washing, the last por- tions being removed by water. 1 Aliphatic ketones react readily in ethereal solution, and the water which is produced may be absorbed by recently ignited potassium carbonate or calcium chloride. In the case of ketophenols or ketoalcohols the hydroxyl group should be acetylated before treatment with phenyl- hydrazine ; acids are usually used in the form of esters, but the sodium salt is sometimes employed a and the condensation promoted by the addition of a mineral acid. 3 Hydrazones may also be prepared from oximes. 4 The carbonyl group in many lactones and acid an- hydrides condenses with phenylhydrazine, 6 but not with hydroxylamine ; B on the other hand, many quinones, such as anthraquinone, do not react with phenylhydrazine or only with one molecular proportion, as in the case of naphthoquinone and phenanthra- quinone, whilst some, such as benzoquinone and tolu- quinone, oxidize it to benzene. 7 Ortho-disubstituted ketones frequently do not react with phenylhydrazine, 8 and certain unsaturated ketoalcohols, such as ethylic acetoacetate 9 and ethylic camphoroxalate, 10 yield monophenylhydrazides, the ketonic group being un- 1 Thorns, B. 29, 2988. 2 Bamberger, Ibid. 19, 1430. 8 Elbers, Ann. 227, 353. 4 Just, B. 19, 1205. von Pechmann, Ibid. 20, 2543, foot-note. 5 R. Meyer and E. Saul, Ibid. 26, 1271. Hemmelmayr, M. 13, 667. Ephraim, B. 26, 1376. 8 v. Meyer and Miinchmeyer, Ibid. 19, 1706. Holle, J. pr. 33, 99- ' S. p. 538. 8 Baum, B. 28, 3209. V. Meyer, Ibid. 29, 830, 836. 9 Nef. Ann. 266, 52. 10 Bishop Tingle, Am. Chem. Journ. 20, 339. A. Tingle and Bishop Tingle, Ibid. 21, 258. DETERMINATION OF CARBOXYL. 63 affected. Hydroxyketones and aldehydes of the ali- phatic series yield phenylosazones, a portion of the phenylhydrazine being simultaneously reduced to aniline and ammonia. 3 A method has been described for the purification of commercial phenylhydrazine. 4 (B) Preparation of Substituted Hydrazones. The chief substitution product of phenylhydrazine which has hitherto been employed for the preparation of phenylhydrazones is the parabromo-derivative. Preparation ofParabromopJienylhydrazine.* Phenyl- hydrazine (20 grams) is poured into hydrochloric acid (200 grams, sp. gr. = 1.19) and the precipitated salt uniformly distributed throughout the liquid, which is cooled to 0° ; bromine (22.5 grams) is now dropped in, the addition occupying 10-15 minutes, the liquid being well shaken during this time. After remaining during twenty-four hours the precipitate is removed, washed with a little cold hydrochloric acid, dissolved in water, and treated with sodium hydroxide in excess. The base separates in flocculent crystals which are extracted with ether, the ether evaporated, and the residue recrystallized from water. The hydrochloric acid mother liquor contains bromodiazobenzene chlo- ride, which is reduced by the addition of stannous chlo- ride (60 grams) ; the precipitate is separated, washed with concentrated hydrochloric acid, and treated with water and alkali, the base being collected and purified 3 E. Fischer and Tafel, B. 20, 3386. 4 B. Overton, Ibid. 26, 19. 5 Michaelis, Ibid. 26, 2190. 64 RADICLES IN CARBON COMPOUNDS. in the manner described above. The yield is 80 per cent. Bromophenylhydrazine requires to be protected from light and air; it should be kept in the dark in well-stoppered colored bottles from which the air has been displaced by carbonic anhydride or coal-gas. In these circumstances, if the compound has been highly purified and dried, it may be retained for years with- out change ; colored specimens may be readily puri- fied by recrystallization from water, to which a few drops of sodium hydroxide should be added. The pure compound melts at I07°-I09°, the acetyl deriv- ative at 1 70V Substituted PhenylJiydrazones. Parabromophenylhydrazine is well adapted for the identification of certain sugars, such as arabinose, and has also been used in the investigation of ionone and irone; 3 it is generally employed in acetic acid solution, care being taken to prevent the liquid from boiling, as, in these circumstances, acetyl parabromo- phenylhydrazine is formed. 4 Paranitrophenylhydrazine also gives well defined condensation products with many aldehydes and ketones which serve for their identification. The reaction usually proceeds in aqueous solution with the hydrochloride, but the free base in alcohol or acetic acid may be employed. 5 In addition the following substituted phenyl- hydrazines have been used for the production of 1 Tiemann and Krtiger. 9 E. Fischer, B. 24, 4221, foot-note. 8 Tiemann and Krtiger, Ibid. 28, 1755. 4 Ibid. 26, 2190. 6 E. Bamberger & Kraus, Ibid. 29, 1834. Bamberger, Ibid. 32, 1806. E. Hyde, Ibid. 32, 1810. DETERMINATION OF CARBONYL. 65 phenylhydrazones : dibromo-, symmetrical tribromo-, tetrabromo-, parachloro-, pariodo-, and metadiiodo-, 1 whilst some derivatives of diphenylhydrazine have also been described. 3 (C) Indirect Method. 3 This method depends on allowing the aldehyde or ketone to react with excess of phenylhydrazine ; the excess, together with any hydrazide, is then oxidized by means of boiling Fehling's solution, the liberated nitrogen being collected ; phenylhydrazones are not decomposed by this treatment. The reagents required are as follows: Copper sulphate solution (70 grams Cu So 4 .5H a O in 1 liter). Alkaline solution of sodium potassium tartrate, made by dissolving 350 grams of the tartrate, and 260 grams potassium hydroxide in 1 liter; these two solutions are mixed in equal volumes to form the Fehling's solution. Sodium acetate (10 per cent solution). Phenyldrazine hydrochloride (5 per cent solution.) The analysis is made by mixing the compound under examination (0.1-0.5 gram) with an accurately meas- ured quantity of the phenylhydrazine hydrochloride solution (1 part) and the sodium acetate solution (i£ parts) in a 1 00 cc measuring flask. The phenylhy- drazine hydrochloride is taken, if possible, in quantity sufficient to yield 15-30 cc nitrogen. Water is now added to the mixture in the flask so as to make the volume about 50 cc, and the liquid is heated on the 1 A. Neufeld, Ann. 248, 93. 2 R. Overton, B. 26, 10. 8 H. Strache, M. 12, 524; 13, 299, Benedikt and Strache, Ibid. 14, 270. 66 RADICLES IN CARBON COMPOUNDS. water-bath during 15-30 minutes; it is then cooled, diluted to the mark, well shaken, 50 cc transferred to the dropping funnel T, Fig. 8, and the determination Fig. 8. conducted in the manner described below. The flask A has a capacity of 750-1000 cc, and contains 200 cc of Fehling's solution, which is boiled whilst a rapid current of steam is blown in from the flask B. The tubes D and R must be flush with the rubber stoppers so as to promote the removal of air. The tube R is in two pieces, joined by the rubber tube K; its lower end is covered with a piece of rubber-tube E and dips below water in the dish W. The current of steam is continued until the bubbles of gas collected are very small, it is impossible, in a reasonable time, to remove all the air and a titration of the phenylhy- drazine hydrochloride solution is made, previous to the actual determination, so as to allow for this error. 1 gram of the salt eliminates about 155 cc nitrogen, therefore, for the titration, 10 cc of the solution is accurately measured out, mixed with the needful DETERMINATION OF CARBON YL. 67 proportion of sodium acetate solution, diluted to 100 cc, and 50 cc transferred to the dropping funnel; the end of this is drawn out at 5 and cut off at an angle so as to avoid the collection of bubbles of gas ; before the funnel is fixed in place the stem is filled with water. When the greater portion of the air has been removed from the apparatus in the manner described above, the phenylhydrazine salt is allowed to mix with the Fehling's solution, care being taken to prevent the water flowing from IV'mto A. When all has been added the funnel is washed out twice with hot water, which is, of course, also allowed to run into A. If the boiling is sufficiently brisk the evolution of nitro- gen is completed in 2-3 minutes. As soon as the bubbles are as small as those of the air at the com- mencement of the experiment the heating is stopped, the hot water in W replaced by cold, the excess escap- ing into the dish C and the measuring tube removed, to a cylinder of cold water. The actual determina- tion is made immediately after the completion of the blank experiment and, if necessary, repeated a second or third time; since 200 cc Fehling's solution readily liberates 150 cc nitrogen, the quantity taken in A amply suffices for three or four carbonyl determina- tions. As benzene is produced during the oxidation of the phenylhydrazine, a drop of it will be found floating on the surface of the water inside the measuring tube; this may be allowed for in measuring the gas or it may be removed. In the former case a little more benzene is introduced into the tube by means of a bent pipette, and, after remaining during a short time, the volume 68 RADICLES IN CARBON COMPOUNDS. of nitrogen is read off in the ordinary manner ; its reduction to o ° and 760 mm may be made by the help of the following tLble, the values in the second column being subtracted from the ob- served height of the barometer : mperature. Tension of benzene -j- water i5° C. 72 7 mm. 16 76.8 17 80.9 18 85.2 19 89-3 20 93-7 21 98.8 22 IO3.9 23 IO9. 1 24 H4-3 25 119.7 The values given above are in part obtained by interpolation from Reg- nault's results and are therefore subject to error; for this reason, and on account of the high vapor tension of benzene its removal is advisable. 1 To accom- Fig 9. plish this alcohol is added to the tube of nitrogen, which is placed in a cylinder of about its own length filled with water (Fig. 9). A glass tube 5 mm. in diameter is bent into the form of a U as shown in the figure, the smaller limb terminating in a jet and being of such length that, when the bent Benedikt and Strache, M. 14, 373. DETERMINATION OF CARBONYL. 69 portion rests on the bottom of the cylinder, the jet is several cm below the surface of the water. The longer limb rises about 40 cm above the surface of the water and is connected at the end by means of a piece of thick walled rubber tube with a dropping funnel. The U tube is completely filled with water and placed in the position shown in the figure. Alcohol (about 200 cc) is now allowed to flow from the funnel into the measuring tube; it issues from the jet in a fine stream and absorbs the benzene vapor pres- ent in the nitrogen as well as that floating on the water; the alcohol is removed in a similar manner by washing with at least 400 cc water, and the tube of nitrogen then removed to another cylinder of water, where, after a suitable interval, the volume of gas is read. The amount of carbonylic oxygen O is ob- tained from the volume of nitrogen, corrected to o° and 760 mm, by the expression : O — (g. V. — 2 V .). 15.96 ioc> ^ , r _ Tr 0.07178 °- 0012562 * 2~t^2 ' ~T io = °=& V ' ~ 2V »~-^ *> where g is the weight of phenylhydrazine hydro- chloride taken, V the volume of nitrogen evolved by 1 gram of this salt, 5 the weight of the compound em- ployed, and V the volume of nitrogen obtained at N. T. P. The theoretical value of V is 154.63CC, but the value employed in the calculation is that obtained in the blank experiment. If the phenylhydrazone is in soluble in water or dilute alcohol, or if sparingly soluble phenylhy- drazides are formed, the preparation of the phenylhy- drazone must be made in alcoholic solution ; in this yo RADICLES IN CARBON COMPOUNDS. case the weight of the column of liquid in the funnel T, Fig. 8, will not be sufficient to overcome the pressure of steam in the flask A. This difficulty may be surmounted by fitting the open end of the funnel with a rubber stopper, carrying a tube and stop-cock. By blowing through the tube the alcoholic liquor is forced into the flask, but great care is necessary, as the sudden evolution of alcoholic vapor may eject liquid from flask A to B, or may even lead to an ex- plosion. A second objection to the use of alcohol is that, at its boiling-point, ketones do not always react quantitatively with phenylhydrazinc. Both difficulties may be overcome by the use of recently boiled amylic alcohol as solvent, the portion of it which passes over with the nitrogen being subsequently removed simul- taneously with the benzene, and in the same manner, by washing with alcohol and water. (2) PREPARATION OF OXIMES. 1 In the preparation of oximes the hydroxylamine is employed in the form of the free base, the hydro- chloride, as potassium hydroxy laminesulphonatc, or zinc dihydroxylamine hydrochloride. Aldoximes are obtained by treating aldehydes with an equimolecular proportion of hydroxylamine hydrochloride in con- centrated aqueous solution, adding sodium carbonate (0.5 mol.), and allowing the mixture to remain at the ordinary temperature during £-8 days. The oxime is extracted with ether, the solution dried over calcium 1 V. Meyer and Janny, B. 15, 1324, 1525. Janny, Ibid. 15, 2778; 16, 170. DETERMINATION OF CARBONYL. 7 1 chloride, and, after the removal of the ether, the residue rectified. An aqueous-alcoholic solution is used for aldehydes insoluble in water, and those that are readily oxidizable, such as benzaldehyde, are treated in flasks from which the air has been removed by means of carbonic anhydride. 1 Oximes of the carbohydrates, which are so readily soluble in water that they cannot be separated from the inorganic salts resulting from the use of hydroxylamine hydrochloride and sodium carbonate or sodium hydroxide, are treated with the calculated quantity of free hydroxylamine in alcoholic solution ; after several days the oxime gradually crystallizes out. a Alcoholic solution of hydroxylamine is prepared by intimately mixing the hydrochloride with the necessary quantity of potassium hydroxide together with a little water, and then adding absolute alcohol, the clear liquid is after- wards separated from the precipitated potassium chloride. 3 The solution gradually acquires a slight yellow color, 4 which may be obviated by substituting sodium ethoxide for the potassium hydroxide. Ketoximes are usually formed less readily than the aldoximes ; for their preparation the ketone is mixed with sodium acetate and hydroxylamine hydrochloride in aqueous or alcoholic solution in the necessary propor- tions, and the liquid heated on the water-bath during 1-2 hours, or the ketone, in alcoholic solution, may be heated in a sealed tube with the hydrochloride at i6o°-i8o° during 8-10 hours, 5 but sometimes in 1 Petraczek, B. 15, 2783. » Wohl, Ibid. 24, 994. S., p. 367. 3 Volhard, Ann. 253, 206. 4 Tiemann, B. 24, 994. 6 Homolka, Ibid. 19, 1084. 72 RADICLES IN CARBON COMPOUNDS. these circumstances, instead of the oximes derivatives of them are formed by intramolecular rearrangement. 1 In many cases it is highly advantageous to allow the carbonyl derivative and the hydroxylamine to react in strongly alkaline solution ; the proportions which usually give the best results are ketone, in alcoholic solution (i mol), hydroxylamine hydrochloride (1.5-2 mol), alkaline hydroxide (4.5-6 mol); the last two are dissolved in the smallest requisite quantity of water. 2 The reaction is often completed at the ordinary temperature in a few hours; occasionally heating on the water-bath is desirable. This method cannot of course be used with ketones or aldehydes that are attacked by alkali, nor in the preparation of dioximes which readily change into their anhydrides in the presence of alkali. In such cases an acid liquid may be employed. Quinone furnishes an example of this. In alkaline solution it is reduced by hydroxylamine to hydroquinone, whilst in aqueous solution, in pres- ence of hydrochloric acid and hydroxylamine hydro- chloride, a dioxime is formed. 3 Some compounds, such as phenylglyoxalic acid, yield oximes both in alkaline and acid solution. 4 Oximes of ketonic acids may be obtained by treating the alkali salt in neutral aqueous solution with hydroxylamine hydrochloride ; the precipitation of oxime usually commences at once, especially if the liquid is warmed. 6 Sometimes it is advisable to convert the acid into its methyl ester and 1 Thorp, B. 26, 1261. 2 Auwers, Ibid. 22, 609. 3 Nietzki and Kehrmann, Ibid. 20, 614. 4 S. p. 370. 5 Bamberger, Ibid. 19, 1430. DETERMINATION OF CARBONYL. 73 avoid the use of excess of hydroxylamine hydrochloride so as to prevent the formation of nitriles. 1 Potassium hydroxylamine sulpJionate, supplied by the " Badischen Anilin- und Sodafabrik," under the name " Reducirsalzes," has been employed, in aqueous- alcoholic solution, for the preparation of oximes ; 2 in presence of free alkali it is hydrolysed, and the liber- ated hydroxylamine acts in the nascent state on the carbonyl compounds. 3 It also possesses the advantage of cheapness. Zinc diJiydroxylamine hydrochloride ', ZnCl a .2 N H a OH, has been used chiefly for the preparation of ketoximes 4 as its resolution into hydroxylamine and anhydrous zinc chloride facilitates the elimination of water. It is prepared 5 by adding zinc oxide (1 part) to hydrox- ylamine hydrochloride (2 parts) in boiling alcoholic solution. The boiling is continued in a reflux appa- ratus for a few moments, and the liquid allowed to cool. The compound is deposited as a crystalline powder which dissolves sparingly in water or alcohol, but readily in solutions of hydroxylamine hydro- chloride. Ortho- and paraquinones and metadiketones cease to react with hydroxylamine if several atoms of hy- d ogen in the ortho-position are replaced by haloid atoms or alkyl groups. Aromatic ketones of the formula (CH 3 .C) a C.COR, where R = phenyl or an 1 1 Garelli, Gazz 21, 2 % Ibid. 2173. 2 Kostanecki, B. 22, 1344, 3 Raschig, Ann. 241, 187. 4 Crismer, Bull. soc. chim. [3], 3, 114. 6 B. 23, R. 223. 6 Kehrmann, Ibid. 21, 3315. Herzig and Zeisel, Ibi i. 21, 3494. Cf. Ibid. 22, 1344. 74 RADICLES IN CARBON COMPOUNDS. alcohol radicle, are also incapable of forming oximes; 1 indeed, the presence of carbonyl, which does not yield oximes, in such compounds as acids, 2 amides,' or esters 4 may, by the production of hydroxamic acids, lead to erroneous results. The statement that alkyl salicylates and hydroxylamine give salicylhydroxamic acid requires further investigation. 4 The unsaturated ketoalcohol camphoroxalic acid C:C.OH.CO.OH c - H - CHI, . COOR + N,. Rather more than the theoretical quantity of iodine is accurately weighed, dissolved in absolute ether, and added, by means of a burette, to a known quantity 1 Curtius, J. pr. 146, 422. 100 DETERMINATION OF THE DlAZO GROUP, ETC. IOI of the diazo-compound also in ethereal solution; the end of the reaction is indicated by a sharp change in the color of the diazo-compound from lemon yellow to red; towards the conclusion of the titration the reaction is facilitated by warming the liquid on the water-bath. The excess of iodine solution is run into a tared flask, the ether cautiously removed, and the residue weighed. Unless the compound employed is in a high state of purity the change of color in the liquid takes place long before all the nitrogen has been expelled. (2) ANALYSIS OF THE IODINE DERIVATIVE. The iodine in the iodo-compound may be deter- mined in the ordinary manner, or the following simpler method, first used in the investigation of diazoaceta- mide, 1 may be employed. A weighed quantity of the substance is placed in a tared beaker, dissolved in a little absolute alcohol, and iodine added until a permanent red coloration is obtained. The alcohol is volatilized on the water-bath, the excess of iodine removed by cautious heating, and the crystalline residue weighed. In this case also the compound employed must be pure. (3) DETERMINATION OF THE NITROGEN IN THE WET WAY. On account of the great volatility of the aliphatic ethereal diazocarboxylates the method of nitrogen 1 Curtius, J. pr, 146, 423. 102 RADICLES IN CARBON COMPOUNDS. Fig. 12. determination described on p. 81 cannot be employed. This difficulty is overcome * by the use of the apparatus „ shown in Fig. 12. A is a large gas cylinder contain- ing water, r a capillary tube, the upper open end of which rises a little above the level of the water in A. E is a gas measuring tube, B a small condenser fitted to the little flask C by means of a rubber stop- per; through this a platinum wire also passes. It is bent in the manner shown and carries a glass-stoppered vessel such as is employed in vapor density deter- minations. The flask C is partially filled with well boiled, highly dilute sulphuric acid, the compound (about 0.2 gram) weighed into the small vessel s, and the apparatus fitted together air-tight. When the air in the apparatus is in equilibrium with the atmosphere, which can readily be observed if a drop of water is placed in r, the volume of air in the eudiometer tube is read off, and the temperature noted. The vessel s is now dropped into the acid, which is gradually heated to boiling; the decomposition is completed in a few minutes. The apparatus is allowed to cool com- pletely, the level of water in and outside the tube E adjusted, and the volume, temperature, and pressure noted ; the difference in volume from the previous reading gives the quantity of nitrogen evolved. As a 1 Curtius, J. pr. 146, 417. DETERMINATION OF THE DIAZO GROUP, ETC. IOJ rule the pressure does not materially change during the experiment. Compounds containing an amino as well as a diazo- group, such as diazoacetamide, may be decomposed by means of dilute hydrochloric acid ; after the evolu- tion of nitrogen is completed the ammonium chloride in the flask c may be precipitated with platinum chloride and the amido and diazo nitrogen thus sepa- rately determined in one operation. (B) Aromatic Diazo Compounds. (Diazonium Derivatives C.N. OH) in N The diazo group in aromatic compounds is usually determined by the preceding method ' (3), but it is preferable to employ a Lunge's nitrometer and 40 per cent sulphuric acid. 2 If the compound is unstable and the determination is made in a current of carbonic anhydride 3 the air should be expelled at a temperature of . 4 Sulphuric acid, sp. gr. = 1.306, has a vapor tension of 9.4 mm at 15 o t> DETERMINATION OF THE HYDRAZIDE GROUP (NH.NH 2 ). Either the oxidation or iodometric method may be employed. 1 Knoevenagel, B. 23, 2997. v. Pechmann and Frobenius, Ibid. 27, 706. 1 Bamberger, Ibid. 27, 2598. 3 H. Goldschmidt and A. Merz, Ibid, 29, 1369; 30, 671. 4 Hantzsch, Ibid. 28, 1741. 6 Regnault. 104 RADICLES IN CARBON COMPOUNDS. (i) OXIDATION OF HYDRAZIDES. 1 Boiling Fehling's solution hydrolyses acid hydra- zides, and oxidizes the resulting phenyl hydrazine, the nitrogen of which is evolved quantitatively and deter- mined by the method described on p. 65. The com- pound is dissolved if possible in water or alcohol ; hydrazides which do not dissolve are weighed into a small stoppered vessel which is fixed mouth down- wards in the hole of the stopper otherwise occupied by the funnel A, Fig. 8, and is dropped into the boiling solution by means of a glass rod of the same volume. Insoluble compounds may also be treated according to the following method: 3 100 cc Fehling's solution and 150 cc alcohol, together with a few fragments of porcelain, are placed in a 500 cc flask fitted with a doubly bored rubber stopper. In the one hole the tube containing the weighed substance is placed, whilst through the other passes the end of an inclined condenser. The contents of the flask are boiled and the open end of the condenser connected with a bent tube terminating in a short leg which dips below water. When no more air is expelled a measuring vessel full of water is placed over the end of the tube, and the vessel with the substance pressed into the flask by means of a rod. Continued boiling for a short time suffices to liberate all the nitrogen. 1 H. Strache and S. Iritzer, M. 14, 37. Holleman and de Vries, Rec. 10, 229. De Vries, B. 27, 1521; 28, 2611. Petersen, Z. An. 5, 2. 8 H. Meyer, M. 18, 404. DETERMINATION OF THE DIAZO GROUP, ETC. 105 In some cases it is desirable to recover the acid on account of its rarity, or to remove it in order to facilitate the determination, as in the case of stearic acid, the potassium salt of which causes the liquid to froth over. This can be accomplished, if the acid is sparingly soluble in water or dilute hydrochloric acid, by boiling the hydrazide with concentrated hydro- chloric acid, during several hours; the solution is made up to 100 cc, the organic acid removed by means of a dry filter, the first few drops of the filtrate rejected, and 50 cc of the remainder taken for the determination. This method of hydrolysis does not distinguish between hydrazides and hydrazones, as the latter are also acted upon by hydrochloric acid. Ortho- and paratolylhydrazides are oxidized in the same manner as phenylhydrazides, so that the method is also ap- plicable to them. 1 Platinic chloride oxidizes hydrazine hydrochloride in accordance with the equation : N a H 4 .2HCl + 2PtCl 4 *-> N a + 6HC1 + 2PtCl, ; the evolved nitrogen is determined by the method described on p. 101. 2 Hydrazine salts may be titrated by potassium per- manganate in presence of sulphuric acid, provided the concentration of the latter is 6-12 per cent. 1 The re- action is represented by the equation i;N 2 H 4 + 13O m* i 3 H u O + i 4 NH s + ioN,. 1 M. 14, 38. 2 Curtius, J. pr. 147, 37. 3 Petersen, Z. An. 5, 3. 106 RADICALS IN CARBON COMPOUNDS. (2) IODOMETRIC METHOD. 1 Phenylhydrazine and iodine react in accordance with the following equation : C 6 H B NH.NH a + 2 1, ^ 3 HI + N 2 + G.H.I. The interaction is quantitative in highly dilute solu- tion with iodine present in excess. The determination is made by adding to a known volume of N/10 iodine solution the highly dilute solution of the base or its hydrochloride, obtained by hydrolysis as described in the preceding section ; the excess of iodine is then titrated in the ordinary manner. In presence of dilute sulphuric acid iodic acid oxi- dizes phenylhydrazine and this reaction may also be employed for the determination. The strength of the iodic acid solution is ascertained by means of sul- phurous acid of known titre; it is then added, in excess, to the highly dilute solution of phenyl- hydrazine and sulphuric acid, and the mixture again titrated. To the above methods may be added the titration of phenylhydrazine with hydrochloric acid ; methyl- orange is used as indicator, and tolerably accurate results are obtained. 8 DETERMINATION OF THE NITRO-GROUP (NO a ). (A) Titration Method. 3 Organic nitro-compounds are reduced to amino- derivatives by the action of stannous chloride, in 1 E. v. Meyer, J. pr. 149, 115. 8 Strache and Iritzer. 3 H. Limpricht, B. 11, 35. DETERMINATION OF THE DIAZO GROUP, ETC. 107 presence of hydrochloric acid, in accordance with the equation R.NO, + 3SnCl 2 + 6HC1 »-> R.NH, + 3SnCl 4 + 2H,0; the unchanged stannous chloride is determined by titration, and, from the quantity which has reacted, the number of nitro-groups in the original compound may be ascertained, Solution of iodine, or of potas- sium permanganate, is employed for the titration. 1 Reagents Required. (1) Stannous Chloride Solution. Tin (150 grams) is dissolved in concentrated hydrochloric acid, the clear liquid decanted, mixed with concentrated hydro- chloric acid (50 cc), and diluted to I liter. (2) odium Carbonate Solution. Anhydrous sodium carbonate (180 grams) and sodium potassium tartrate (240 grams) are dissolved in water and diluted to I liter. (3) Iodine Solution. Iodine (12.54 grams) is dis- solved in potassium iodide solution and the liquid made up to 1 liter, it will then be approximately N/10, if exactly so 1 cc = 0.0059 g ram Sn = 0.000 655 gram NO a . (4) Starch Solution. This must be dilute, recently prepared, and filtered. Potassium Permanganate Solution. It should be 1 Jenssen, J. pr. 78, 193. S. W. Young and R. E. Svvain, J. Am. (1897), 19, 812-814. Journ. Chem. Soc. (1898), 74, ii, 186. I08 RADICALS IN CARBON COMPOUNDS. N/io, and may be used instead of the iodine, its strength being determined by means of iron. (I) Method of Determination for Non-volatile Compounds. After the titre of the stannous chloride has been ascertained, the nitro-compound (about 0.2 gram) is placed in a 100 cc glass-stoppered flask, stannous chlo- ride solution (10 cc) added, and the liquid warmed during thirty minutes. When cool, the mixture is diluted to the mark, and, after shaking, 10 cc trans- ferred to a beaker by means of a pipette ; a little water is added, then the sodium carbonate solution, until the precipitate which first forms is wholly dissolved ; after the addition of a little starch the iodine solution is run in until a permanent blue coloration is produced. The results of the analysis are calculated according to the formula N0 2 = (a — £). 0.000765 5 gram, where a = the number of cc of iodine solution equiv- alent to 1 cc of the stannous chloride solution, and b = the number of cc of iodine solution required in the determination. If it is desired to use the potassium permanganate 10 cc of the acid liquid, withdrawn as described above, is boiled with ferric chloride, and the ferrous chloride produced is determined in the ordinary manner. (II) Modified MetJiod for Volatile Compounds. Volatile nitro-compounds are weighed in a test-tube about 30 cm by 8 mm, closed with a cork ; the cork is removed, and the tube, together with the stannous DETERMINATION OF THE DIAZO GROUP, ETC. IO9 chloride, placed in a second larger one, 20 cm by 13- 15 mm, which is then sealed. The larger tube may be of thin-wallcd, readily fusible glass, as it will only be subjected to a very slight pressure. The tube is heated in the water-bath during 1-2 hours, and well shaken occasionally; it is then cooled, the contents completely washed into a 100-cc graduated flask, and treated in the manner described in the preceding sec- tion. The use of a sealed tube is sometimes advisable in the case of non-volatile compounds with which low results may be obtained by heating in the stoppered bottle. (B) Diazo Method. 1 Should the preceding method fail to give decisive results the nitro-compound must be reduced to the amino-derivative and this treated in the manner de- scribed on p. 87. As an example metanitrobenz- aldehyde may be converted into metachlorobenzalde- hyde at one operation. 8 It is dissolved in concentrated hydrochloric acid (6 parts), stannous chloride (4.5 parts) added, and after the reduction, without pre- cipitating the tin, it is mixed with the calculated quantity of sodium nitrite and an equal weight of finely divided copper. DETERMINATION OF THE IODOSO- (IO) AND IODOXY- (IO a ) GROUPS. Iodoso- and iodoxy-compounds in presence of glacial acetic, of hydrochloric acid, or of dilute sul- phuric acid liberate from potassium iodide an amount 1 Gattermann, B. 23, 1222. 8 Gattermann, loc. cit. 110 RADICALS IN CARBON COMPOUNDS. of iodine equivalent to their content of oxygen ; one molecule of the former therefore liberates two, and of the latter four atoms of iodine. For the determina- tion the substance is heated on the water-bath during four hours with acidified potassium iodide solution in a sealed tube from which the air has been expelled by carbonic anhydride. 1 The compound may also be digested on the water-bath with concentrated potas- sium iodide solution, glacial acetic acid, in fairly large quantity, and dilute sulphuric acid.' When the re- action is completed the liquid is titrated with N/io sodium thiosulphate solution ; no indicator is required. Whenever hydrochloric acid or sulphuric acid has been employed in the reduction, the iodide, which is pro- duced, always retains some iodine in solution hence, during the titration, it is necessary to warm and shake the liquid until this has all been acted upon by the thiosulphate. The oxygen percentage content of the iodosy- and iodoxy-compounds is given by the o.8.c. ioo c formula O = = 0.08 — , where s is the weight 1000 s s of the compound taken and c the number of cc of N/10 sodium thiosulphate employed. DETERMINATION OF THE PEROXIDE GROUP «} The oxygen of the acyl superoxides may be deter- mined by means of stannous chloride in acid solution. 1 V. Meyer and Wachter, B. 25, 2632. P. Askenasy and V. Meyer, Ibid. 26, 1355, et seq. 2 Willgerodt, Ibid. 25, 3495, et seq. 3 Pechmann and Vanino, Ibid. 27. 1512. DETERMINATION OF THE DIAZO GROUP, ETC. Ill A known quantity of the peroxide is heated during about five minutes, in an atmosphere of carbonic an- hydride, with a measured volume of a titrated, acidified stannous chloride solution. When the liquid is clear the remaining stannous chloride is determined by means of N/io iodine solution. THE IODINE NUMBER. 1 This value expresses the quantity of iodine absorbed by one hundred parts of the substance, usually a fat or higher aliphatic acid. The acids of this series, such as oleic acid, ricinoleic acid, linoleic acid and linolenic acid, as well as their glycerides, absorb the first two, two, the others four and six atoms of iodine, bromine, or chlorine respectively, whilst the corre- sponding saturated compounds, under similar circum- stances, are not affected. The reaction is carried out at the ordinary temperature, the substance being mixed with alcoholic iodine and mercuric chloride solu- tions. 2 The organic products are chloro-iodine addi- tive compounds, some of which have been isolated and characterized. 3 The method is extensively employed in the technical investigation of fats, oils, waxes, resins, etheral oils, caoutchouc, etc., and is some- times useful for scientific purposes, hence a brief de- scription of the method of analysis is given here. 1 Benedikt, "Analyse d. Fette und Wachsarten," III. Edition, p. 148. Allen, "Commercial Organic Analysis," vol. II, 3d Edi- tion. 2 Hiibl, Dingl. 253, 281. 3 R. Henriques and H. Kiinne. B. 32, 389. 112 RADICALS IN CARBON COMPOUNDS. Reagents. (i) Iodine Solution. Iodine (25 grams) and mercuric chloride (30 grams) are each separately dissolved in 95 per cent alcohol (500 cc), free from fusel oil. The mercuric chloride solution is filtered if necessary, and the liquids mixed. The mixing must precede the use of the solution by 6-12 hours as, during this period, the titre rapidly changes. (2) Sodium TJiiosulpJiate Solution. The crystallized salt (24 grams) is dissolved in water and diluted to one liter. It is standardized in the following manner: ' Potassium bichromate (3.8740 grams) is dissolved in water, diluted to one liter, and 20 cc of the liquid transferred to a stoppered bottle containing 10 cc of potassium iodide solution (10 per cent), and 5 cc hydrochloric acid ; the liberated iodine is then titrated in the ordinary manner by means of sodium thiosul- phate, starch being used as indicator; 1 cc of the above bichromate solution liberates O.oi grams of iodine. (3) Chloroform. Its purity is determined by a blank experiment. (4) Potassium Iodide Solution. The salt is dissolved in ten parts of water. (5) Starch Solution. This must be clear and recently prepared. Method of A na lysis. The substance (o. 1 5-1 .0 gram) is mixed with chloro- form (about 10 cc) in a 500—800 cc flask provided with 1 Volhard. DETERMINATION OF THE DlAZO GROUP, ETC. 113 a well-fitting glass-stopper. When the compound has dissolved the iodine solution (25 cc) is added by means#of a pipette which must be manipulated so that equal quantities are delivered in each experi- ment. The flask is well shaken and more chloroform added if needful; should the liquid become almost colorless in a short time a second 25 cc of iodine solu- tion is added, and this repeated, if necessary until, after the expiration of two hours, the liquid appears dark brown. The mixture is now allowed to remain during twelve hours at the ordinary temperature in the dark; it is then thoroughly mixed with at least 20 cc of potassium iodide solution and 300-500 cc of water, and titrated with the sodium thiosulphate solution, the liquid being constantly agitated ; when only a faint color is visible in both the aqueous and chloroform solutions, starch is added and the titration completed. The production of a red precipitate of mercuric iodide, on the addition of water before the titration, indicates that too little potassium iodine has been employed, but this may be corrected by the immediate addition of more. A blank experiment must always be made with 25 cc of the iodine solu- tion under exactly the same conditions as the test, and its titration must immediately precede or follow that of the actual determination. Useful information is sometimes given by the tere- bcn thene n u mber. 1 1 J. Klimont, Ch. Ztg. (1894), No. 35, 37. Ch. R. (1S94), 2, 2. APPENDIX. \6 APPENDIX. WEIGHT OF A CUBIC CENTIMETER OF HYDROGEN PERATURE OF IO°-25°. 1 The observed height of the barometer is reduced to o° by and 2o"-25° respectively. a u- 700 702 704 706 708 710 712 714 716 718 720 722 724 726 728 730 732 734 736 738 740 742 744 746 748 750 752 754 |o. 756 ,0 758 760 762 764 766 768 770 IO°C. mg n° C. 078510. 078740. 078960. 079190. 07942 o. 12° C. mg 078160, 078390. 07861 |o. 07884J0. 079070. o7964 ! o. 079290. o. ,07987 08009 08032 08055 0S078 08101J0 081230. o8i46|o. 08169,0. 08191 o. 08215 o. 08237:0. o8259 | o. 08282.0. 08305 o. 083280. 083510. 083730. 083960. 08419 o. 08441 o. 084640. 0S487 o. 08510.0. 085330. 085550 .08578 08601 08624 o. o, °' .08646 o. 079520. 079750. 079970. 080190. 08043^. 080650. 080870. 081 IOO. 081330. 08156 o. 08 T 79O. 08201 O. 08224O. 08246 o. 082690. 00291 o. 083140. 083370. 083600. 083820. 08404 o. 08428 o. 084500. 08472 08496 08518 08541 08563 085S6 08608 07781 07804 07826 07848 07871 07893 07917 07939 07961 07984 08007 08029 08052 08074 08097 08120 08142 08164 081870 08209 08233 08255 08277 08300 08322 08344 08368 0S390 08413 08435 08458 08481 08503I0. 08525:0 085490 TDg 14° C. rag O.077460. 0.07769 o. o.o779i|o. o o o. o. (). o. o. 0.08571 078I3I0. 078360. 078580. 07881:0. 07903I0, ,o7924jO. 07948:0 0797i|0- ,079930, ,08016 o. ,08038 ,08061 ,08083 08106 08129 08151 08173 08196 0821S 08240 08263 08285 08308 08331 08353 08376 08398 03420 08443 08465 08487 085 1 1 08533 rag 077H 07713 07756 07778 078000 07823 07845 ,07868 07890 07912 07935 07957 07979 08002 08024 08047 08069 08091 08114 O 08136 O 08T58 08l8l 08203 08226 08248J0 082700 08293:0 08315I0 0833S0 083600 083820 08405^0 08428 08450 08473 08495I0 07675 07697 07720 07742 07774 07787 07809 07832 07854 07876 07899 07921 07943 079 6 5 07987 08010 08032 08055 08077J0 080990 [6° C. mg 07639 07661 .07684 07706 07729 .07750 O.07772 o o o 07795 .07817 .07840 07862 .07SS4 07907 .07929 ■07951 07973 •07995 .0S01S .08040 08062 >7 C mg .08084 >.o8io6Jo .08 1 29 !o 08122 o. 08144^0. 081660, 081890.08151,0, 08211 o, 08234 o, 08256 o, .08 ,082780 ,08301,0 ,08323 o .083450 08367 o 08389 08412 08434 08466 'o, 730 08195 o. 082180. 08240 o, 082620. 082850. 08307 o. 08329 o. 08352 o. 083740. 083960. 08418.0. 07603 07625 07647 07670 07692 07714 07736 07759 07781 07803 07S25 07847 07869 c/891 (-7913 07936 07958 07980 08002 08024 08047 08069 08091 08113 08135 08158 08180 08202 08224 0S246 08269 0S29I 0S3I3 08335 08357 08380 A. Baumann, Z. ang. Ch. 1891, 210. APPENDIX. 11/ UNDER A PRESSURE OF 700-770 mm AND AT A TEM- u , t {& ~ 00)0.089523 \ Value of —r—. : TTT\ • 760(1 4- 0.00366/) J subtracting I, 2, or 3 mm for the temperatures io°-i2°, I3°-I9°, i8°C. 19° C. 20° C. 21° C. 22° C. 23° C. 24" C. 25° C mg mg rag mg mg mg mg mg mm O.07557 O.07529 O.07493 O.07455 O.07417 O.07380 O.07340 O.0730O 700 O.07588 0.07552 007515 O.07477 O.07439 O.074OI O.07362 O.07322 702 O.07610 O 07574 O.07537 O.07499 O.07461 O.07422 O.07383 O.07344 704 O.07633 O.07595 O.07559 O.07521 O.07483 O.07444 O.07405 O.07366 706 O.07655 O.07618 O.075S1 O.07543 O.07505 O.07466 O.07427 O.07387 708 O.07677 O.07640 O.07603 O.07565 O.07527 O.07487 O.07449 O.07409 7IO O.07699 O.07662 O.07625 O.07587 O.07548 O.07509 O.07470 O.07431 712 O.07722 O.07684 O.07646 O.07608 O.07570 O.07531 O.07492 O.07452 714 O.07743 O.07706 O.07668 O.07630 O.07592 O.07553 0.075I3 O.07473 716 O.07765 O.07728 O.0769O O.07652 O.07614 O.07574 O.07535 O.07495 718 O.07788 0.07749 O.07712 O.07674 O.07635 O.07596 O 0755O O.07516 720 O.07809 O.07772 O.07734 O.07696 O.07657 O.07618 O.07577 O.07538 722 O.07831 O.07794 O.07756 0.0771-8 O.07679 O.07640 O.07609 O.07560 724 O.07854 O.07816 O.07778 O 07740 O.07701 O.07661 O.07621 O.07582 726 O.07876 O.07838 O.07S00 O.07762 O.07723 O.07683 O.07643 O.07604 728 O.07908 O.07860 O.07822 O.07784 O.07744 O.07705 O.07665 O.07624 73o O.07920 O.07882 O.07844 0.07805 O.07766 O.07727 O.07687 O.07646 732 O.07942 O.07904 O.07866 O.07827 O.07780 O.07748 O.07708 O.07668 734 O.07964 O.07926 O.07888 O.07849 0.07810 O.07770 O.07730 O.07689 736 O.07986 O.07948 O.07910 O.07871 O.07831 O.07792 O.07752 O.07711 738 O.08009 O.07970 O.07932 O.07893 O.07853 O.07813 O.077740.07732 740 O.08030 O.07992 O.07954 O.07915 O.07875 O.07835 O.077950.07754 742 O.08053 O.08014 O.07976 O.07937 O.07897 O.07857 O.07817 O.07776 744 0.0S075 O.08036 O.07998 O.07959JO.07919 O.07879 O.07838 0.07797 746 0.08097 O.08058 O.08020 07981 0.07940 O.07900 O.07860 O.07819 748 O.0S119 O.08080 O.08042 0.08002 O.07962 O.07922 O.07881 O.0784O 75o O.08141 O.08102 O.08063 O.08024 O.07984 O.07944 O.07903 O.07862 752 O.08163 O.08124 O.08085 O.08046 O.08006 O.07966 O.07925 O.07883 754 O.08185 O.08146 O.08107 O.08068 O.08028 O.07987 O.07947 O.07905 756 O.08207 O.08168 O.08129 O.0809O O.08050 O.08009 O.07968 O.07927 758 O.08229 O.0819O O.08151 O.o8ll2 O.08071 O.08031 O.07990 O.07949 760 O.08251 0.082I2 O.08173 O.08134 O.08093 O.08052 O.08012 O.07970 762 O.0S273 O.08234 O.08195 O.08155 081 15 O.08074 O.08033 O.07992 764 O.08295 O.08256 O.08217 O.08177 O.08137 O.08096 O.08055 O.08013 766 O.08318 1 O.08278 O.08239 O.08199 O.0S158 O.08118 O.08076 O.08034 768 O.08341 O.08301 O.08261 0.OS22I, O.08180 O.08139 O.08098 O.08056 770 n8 APPENDIX. TENSION OF AQUEOUS VAPOR. o°C. mm o°C. mm IO.O 9.165 18.0 15.357 10.5 9-474 18.5 15.845 II. 9.792 19.0 16.346 11. 5 10. 120 19-5 16.861 12.0 10-457 20.0 I7-39I 12.5 10.804 20.5 17-935 13-0 11. 162 21.0 18.495 13-5 11.530 21.5 19.069 14.0 1 1 . 908 22.O 19.659 14.5 12.298 22.5 20. 265 15.0 12.699 23.O 20.888 15-5 13.112 23-5 21.528 16.0 I3.536 24.0 22.184 16.5 13-972 24-5 22.858 17.0 14.421 25.0 23-550 17.5 14.882 TABLE FOR THE VALUE OF 999. 1 ■ 3 4 " s 6 7 8 9 00 O . OOOO 010 020 030 040 050 060 071 08l 091 01 101 in 122 132 142 152 163 173 I8 3 194 02 204 215 225 235 246 256 267 278 288 299 03 309 320 33i 34i 352 363 373 384 395 406 04 417 428 438 449 460 47i 482 493 504 515 05 526 537 549 560 57i 582 593 605 616 627 06 638 650 661 672 684 695 707 718 730 74i 07 753 764 776 788 799 811 823 834 846 858 08 0.0870 881 893 905 917 929 941 953 965 977 09 989 *OOI *oi3 *025 *o 3 8 *o5o *o62 *o74 *o87 *099 10 O.IIII 124 136 148 151 173 186 198 211 223 II 236 249 261 274 287 299 312 325 338 35i 12 364 377 390 403 416 429 442 455 468 481 13 494 508 528 534 547 564 574 588 601 614 14 628 641 655 669 682 696 710 723 737 751 15 765 779 793 806 820 834 848 862 877 891 16 905 919 933 947 962 976 990 *oo5 *oi9 *o34 17 0.2048 083 o77 092 107 121 13b 151 166 180 18 195 210 225 240 255 270 285 300 315 33i 19 346 361 376 392 407 422 438 453 469 484 Obach— Ostwald, Z. II. 566. APPENDIX. TABLE FOR THE VALUE OF - II 9 {Continued.) 1 2 3 4 5 6 7 8 9 20 0.2500 516 53i 547 563 579 595 610 626 642 21 658 674 690 707 723 739 755 771 788 804 22 821 837 854 870 887 903 920 937 953 970 23 987 *oo4 *02I *o 3 8 *055 *072 *o8 9 *io6 *I23 *I4I 24 0.3158 175 193 210 228 245 263 280 298 316 25 333 35i 369 387 405 423 441 459 477 495 26 514 532 550 569 587 605 624 643 661 680 27 699 717 736 755 774 793 812 831 850 870 28 889 908 928 947 967 986 *oo6 *025 *045 *o65 29 0.4085 104 124 144 164 184 205 225 245 265 30 286 306 327 347 365 389 409 430 45i 472 31 493 514 535 556 577 599 620 641 663 684 32 706 728 749 771 793 815 837 859 881 903 33 925 948 970 993 *oi5 *038 *o6o *o83 *io6 *I2g 34 0.5152 175 198 221 244 267 291 314 337 361 35 385 408 432 456 480 504 528 552 576 601 36 625 650 674 699 721 748 773 798 813 848 37 873 898 924 949 974 *ooo *026 *o5i *o77 *i63 38 0.6129 155 181 208 234 260 287 313 340 367 39 393 420 447 475 502 529 556 584 611 639 40 667 695 722 75o 779 807 835 863 892 921 4i 949 978 *oo7 *036 *o65 *094 *I23 *I53 *I82 *2I2 42 0.7241 271 301 33i 361 39i 422 452 483 513 43 544 575 606 637 668 699 731 762 *794 825 44 857 889 921 953 986 *oi8 *o5i *o83 116 45o *I49 45 0.8182 215 248 282 315 349 382 416 484 46 519 553 587 622 657 692 727 762 797 832 47 868 904 939 975 *OII *o 4 8 *o8 4 *I2I *I57 *i 9 4 48 0.9231 268 305 342 380 418 455 493 53i 57o 49 608 646 685 724 763 802 841 881 920 960 50 1. 000 004 008 012 016 020 024 028 033 037 51 041 045 049 053 058 062 066 070 o75 079 52 083 088 092 096 IOI 105 no 114 119 123 53 128 132 137 141 146 151 155 160 165 169 54 174 179 183 188 193 198 203 20S 212 217 55 222 227 232 237 1 242 247 252 257 262 268 56 273 278 283 288 i 294 299 304 309 315 320 57 326 33i 336 342 ; 347 353 358 364 37o 375 58 38i 387 392 398 j 404 410 415 421 427 433 59 439 445 45i 457 ' 463 469 475 484 488 494 120 APPENDIX. TABLE FOR THE VALUE OF :ooo — a {Continued.) 1 2 3 4 s 6 7 8 9 60 1.500 506 513 519 525 532 538 545 551 556 61 564 571 577 584 59i 597 604 611 618 625 62 632 639 646 653 660 667 674 681 688 695 63 703 710 717 725 732 740 747 755 762 77o 64 77S 786 865 793 801 S09 817 825 833 841 924 849 65 857 874 8S2 890 899 907 9i5 933 66 941 950 959 967 9"/6 985 994 *oo3 *OI2 "021 67 2.030 040 049 058 067 o77 086 096 I06 115 68 125 135 145 155 165 175 185 195 205 215 69 226 333 236 247 257 367 268 279 289 300 413 311 425 322 70 344 356 378 390 401 436 7i 448 460 472 484 497 509 521 534 546 559 72 57i 584 597 610 623 636 650 663 676 690 73 704 717 73i 745 759 774 788 802 817 831 74 846 861 876 891 906 922 937 098 953 968 984 75 3.000 016 032 049 065 082 ii5 132 149 76 167 184 202 219 237 255 274 292 3IO 329 77 348 367 ^86 405 425 444 464 484 505 525 78 545 566 587 608 630 651 673 695 717 739 79 762 785 808 831 854 878 902 926 950 975 80 4.000 025 051 076 102 128 155 181 208 236 81 263 291 319 348 376 405 435 465 495 525 82 556 587 618 650 682 7*4 747 780 814 848 83 882 917 952 988 *024 *o6i ♦098 *135 *I73 *2II 84 5-250 289 329 369 410 452 494 536 579 623 85 667 711 757 803 849 897 944 993 *042 *og2 86 6.143 194 246 299 353 407 463 519 576 654 «7 692 752 813 874 937 *ooo *o65 *i30 *i97 ^264 88 7-333 403 475 547 62 r 696 772 850 929 *oo9 89 8.091 174 259 346 309 434 417 524 615 769 753 804 870 901 90 9 000 101 204 526 638 989 9i 10. 11 io.33 10.36 10.49 10.63 10.77 10.90 11.05 11.20 ii-35 92 11.50 11.66 11.82 11.99 12. 16 12.33 12.51 12.70 12.89 x 3 °8 93 13.29 13-49 I3.7I 13-93 14.15 14.38 14.63 14.87 15.13 15.39 94 15.67 15.95 16.24 16.54 16.86 17.18 17.52 17.87 18.23 18.61 95 19.00 19.41 19.83 20.28 20.74 21.22 21.73 22.26 22. 81,23.39 96 24.00 24.64 25.32 26.03 26.78 27-57 28.41 29.30 30.25 31-26 97 32.33 33.4834.71 36.04 37-46 40.67 42.48 44.4546.62 98 49.00 51.6 54-6 1 57-8 61.5 65.7 70.4 75-9 82.3 89.9 99 99.0 no 124 1 142 166 1 199 1 249 332 499 ! 999 INDEX OF AUTHORS. Allen, A. H in Anderlini 4, 61 Angeli, A 88 Askenasy , P no Auwers, K , 72 B Baeyer, A. v 74,77,78 Bamberger, E 19, 62, 64, 72, 103 Bamberger, M 35,37 Barth 12, 20 Barus 46 Baum 62, 74 Baumann 18, 57, 59, 116 Beckmann 8, 32, 40 Benedikt 4, 10, 35, 36, 37, 65, 68, in Berthelot, D 50 Biginelli 74 Blau, Fr 82 Boeris 99 Bouveault 91 Buchka 4, 15 C Cahart 50 Cahn, A 80 121 122 INDEX OF AUTHORS. Cain 90 Cavazzi 88 Ciamician 14, 99 Claisen, L 6, 20, 22, 23 Claus 74, 91 Cohen, E 47 Collie, N 89 Crismer 73 Curtius 86, ioo, 101, 102, 105 D Danck worth 10, 18 Davies 74 Dedichen 86 Delepine 83 Deninger, A 6, 21 Diamant, J 8 Dobriner, P 17 E Ebert 49 Eckhardt 42 Ehmann, L 35 Elbers 62 Ephraim 62 Erb 9°. 9 1 Erdmann 11, 15, 3° Erk 15 Erlich 4 F Feist 6, 21 Feit 74 Feitler 88 Fischer, E 45,60,63,64,93 Franchimont 8 Fresenius 15 Freund 45 INDEX OF AUTHORS. 1 23 Frobenius 103 Fuchs, F 52, 56 Garelli 73 Gattermann 29, 87, 88, 109 Ghiro 4 Giraud, H 93 Goldschmidt, H 103 Goldschmiedt 12, 14, 17, 20, 21, 31, 51 Graebe 4, 28 Grandmougin 86 Green, A. G 85 Gregor, J 39 Griess, P 86 Groger, M 59 Griissner 35 Gumpert 32 Guyot 28 H Hagen 44. 45 Haitinger 43 Haller 28 Hautzsch 91, 103 Harpe, De la 84, 93 Harries, C 74 Hawkins 86 Hemmelmayr 14, 17, 21, 51, 62 Henriques, R ill Herzfeld 13, 80 Herzig, J 5, n, 14, 15, 28, 38, 73, 94, 99 Heuser 75 Heyl, G 92 Hinsberg 24, 27 Hirsch, R 85 Hoffmann, C 74 Hoffmann, E 20 Hofmann, A. W 31, 89, 90 124 INDEX OF AUTHORS. Holle 62 Hollemann 104 Homolka 42, 71 Hormann, O 7 Hiibl in Huth 30 Hyde, E 64 I Iritzer, S 104,106 J Jackson, F. L 23 Jacobson, P 29, 80, 90, 92 Janny 70 Jassoy 27 Jeaneraud 74 Jehn, C 52 Jenssen 107 Jones, H 46 Just 62 K Kehrmann 72, 73 Kinnicutt, L. P 86 Klimont, J 113 Klobukowsky 8, 11 Knoevenagel 103 Knop 57 Knorr 26 Kohlrausch 47 Kormann, W 81 Kostanecki 28, 73 Kraus 64 Kruger 64, 77 Kunne, H in Kux 57 INDEX OF AUTHORS. 125 L La Coste 8 Landsiedl 5 Lassar-Cohn 42 Lehmann 74 Lieben 10,12,43 Liebermann, C 7. 14, 21, 44, 45 Limpricht, H 106 Lossen 18, 19 Lucas 91 M Mcllhiney, P. C 52 Marchlewsky 28 Meldola 86 Menschutkin 83 Merz, A 103 Meyer, E. v 106 Meyer, H 16, 25, 38, 57, 94, 99/104 Meyer, R 16, 25, 62 Meyer, V 20, 29, 44, 62, 70, 74, 80, 90, 91, 92, no Meyer 42 Michael, H. A 8, 16 Michaelis 63 Michel, 86 Munch 91 Munchmeyer 62 N Nef , J. U 63, 74, 86 Neufeld, A 65 Nietzki 72 Nolting 86 O Obach 118 Ostwald, W 46, 48, 118 126 INDEX OF AUTHORS. otto : . 23 Overton, B 61, 63 Overton, R 65 P Panormow 18 Patterson 50 Pechmann, v 18, 28, 62, 103, no Perkin, W. H., Sen 28 Perkin, W. H., Jun 42 Petersen 104, 105 Petraczek 71 Pomeranz 38 Pum, G 24, 37 R Radziszewski gi Raschig 73 Regnault 103 Re verdin 84, 93 Richards, T. W 44 Rideal, S 85 Rolfe, G. W 23 S Sachsse 81 Sandmeyer 87 Sarauw 4 Saul, E 62 Schall 15 Schiaparelli, C 24 Schiff 5, 12, 14 Schlomann 22, 24 Schmidt, G 29 Schmiedeberg 42 Schmolge • 13 Schopf 22 Schotten 22, 23, 24 INDEX OF AUTHORS. \2J Schreder 20 Schultz 11 Schulze • 15 Schunk 28 Schiitzenberger 13 Seelig 5, 62, 72, 91 Silber 14 Sisley, P 16 Skraup 19 Smith, Alex 42 Smoeger 13 Snape 31, 32 Speier 45 Stange 75 Stallburg 90 Strache, H 65, 68, 104, 106 Strouhal 46 Sudborough 90, 9T, 92 Swain, R. E 107 T Taf el 63 Tessmer $1, 32 Thiele 74. 75, 78, 79 Thompson 22, 23 Thorns 62 Thorp 72 Tickle, T 89 Tiemann, F 64, 71, 77 Tingle, A 45,63 Tingle, J. Bishop 45, 63, 74 U Ulzer 10 V Valden 46 Valeur 8 128 INDEX OF AUTHORS. Vanin no Vohl 52 Volhard 40,71,112 Vongerichten 26, 32 Vortmann n Vries, de . 104 W Wachter no Wagner 57 Wallbaum 91 Wiedemann 49 Willgerodt no Wislicenus 6, 14 Wohl 71 Wolff 80 Wright 10 Y Young, S. W 107 Z Zanoli . 31 Zeisel.S 10, 12, 28, 33, 37, 38, 41, 73 INDEX OF SUBJECTS. A Acetic acid 3 glacial 5 , 8 anhydride 5,7 Acetylation, methods of 5 Acetyl chloride 5, 6 derivatives, isolation of 9 preparation of 5 groups, determination of 9 (additive method) 14 (distillation method) 15 (potassium acetate method).. 14 Acids, electrolytic conductivity of 46 etherification of 44 titration of 43 Acylation 3 Aliphatic amino groups, determination of 81 diazo-compounds 100 Alkylation 3 of hydroxyl groups 28 Amidodimethylaniline (/) derivatives 80 group, determination of 91 guanidine derivatives, preparation of 78 picrate derivatives, preparation of 80 salts, preparation of 78 Amines, acetylation of 83, 89 salts of 82, 89 Amino groups, determination of 81 Aqueous vapor, tension of 118 129 130 INDEX OF SUBJECTS. Aromatic amino groups, determination of 83 diazo-compounds 103 Authors, index of 121 Azoinide method, for determination of amino group 86 B Barium hydroxide, hydrolysis by 9, n Basicity of acids, determination of by ammonia method 52 carbonate method 51 hydrogen sulphide method 52 iodine-oxygen method 57 Benzene and water, tension of 68 Benzoic acid 3 acids, substituted 3 anhydride 17, 21 Benzoyl chloride 17, 18 derivatives, analysis of 24 preparation of 17 Benzyl derivatives 28 /^-Brornbenzoic anhydride 17, 22, 23 21 hydroxide, hydrolysis by 9, 10 Stearic anhydride 27 Substituted benzoic acids 17, 22, 23 acylation by means of 23 hydrazones, preparation of 63, 64 phenylhydrazones, preparation of 63, 64 Sulphuric acid, hydrolysis by 10, 13 T Tables 1 16 et seq. Table of tension of benzene and water 68 water 118 weight of a cc of hydrogen 116 W Water, hydrolysis by 9, 10 Water and benzene, table of tension of 68 hydrolysis by 9, 10 table of tension of 118 SHORT-TITLE CATALOGUE OF THE PUBLICATIONS OF JOHN WILEY & SONS, New York. London: CHAPMAN & HALL, Limited. ARRANGED UNDER SUBJECTS. Descriptive circulars sent on application. Books marked with an asterisk are sold at net prices only. All books are bound in cloth unless otherwise stated. AGRICULTURE. Cattle Feeding— Dairy Practice — Diseases of Animals — Gardening, Etc. Arinsby's Manual of Cattle Feeding, 12mo, $1 75 Downing's Fruit and Fruit Trees 8vo, 5 00 Grotenfelt's The Principles of Modern Dairy Practice. (Woll.) 12mo, 2 00 Kemp's Landscape Gardening 12mo, 2 50 Loudon's Gardening for Ladies. 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