IRLF ORGANIC CHEMISTRY -FOR THE- LABORATORY. BY w. A. NOYBS, FH.E>., PROFESSOR OF CHEMISTRY IN ROSE POLYTECHNIC INSTITUTE, TERRE HAUTE, IND. E ASTON, PA.: CHEMICAL PUBLISHING CO. 1897. COPYRIGHT, 1897, BY EDWARD HART. PREFACE. The science of organic chemistry rests, for its experi- mental foundation, on the preparation, usually by syn- thetical means, of pure compounds. Without a knowl- edge, based on personal experience in the laboratory, of the relations involved and the methods which may be used in such preparations, no satisfactory knowledge of the science can be acquired. It has been the purpose of the author in writing this book to classify the most im- portant of the laboratory processes which have been used in the development of the science and to illustrate them by concrete examples. Two distinct purposes have been kept in view. The first has been to furnish the beginner with sufficiently full and accurate directions, and clear, concise, theo- retical explanations of processes which have been found successful in practical laboratory experience. The second object has been to furnish the more advanced student and practical worker with a guide which will aid him in the selection of processes which are likely to be successful for the preparation of compounds which he may desire to use. It is for this second reason, partly, that the number of preparations given is considerably greater than it IV PREFACE. would be profitable for the average student to prepare, and that the references to the literature have been made quite full. The student who uses the book is very earnestly ad- vised to begin each preparation with a careful study of the directions given, and also of the literature of the subject. For the time being, he should make himself thoroughly familiar with all of the important relations of the substance with which he is working, and with other methods of preparation which might be used. A comparatively few preparations carefully studied in this way will be of greater value than a much larger number mechanically executed by simply following the directions of the book. The successful student must be able to use intelligently the larger handbooks, especially that of Beilstein, and the original sources in chemical jour- nals. It need scarcely be remarked that a satisfactory working knowledge of organic chemistry cannot be ac- quired without the ability to use German books. In some cases it may be well to undertake the prepa- ration of analogous substances in place of the ones which are given. The majority of the processes de- scribed should be viewed from the standpoint that they are applicable to many other similar cases, though slight modifications are often necessary, and as to that the student should satisfy himself by examination of the literature before he goes on with his work. In re- search work chemists very often help themselves by a careful study of the properties of bodies related, or anal- ogous to those which they wish to prepare, and the PREFACE. V habit of making comparisons of this kind is very valua- ble. It is not the intention of the author that the order of the book should be necessarily, or, indeed, usually fol- lowed by the student. He has a very firm conviction that laboratory work of the sort provided for in this book should always accompany the lecture-room or text-book work in organic chemistry, and that the frequent lack of interest in the subject is often due to the fact that the laboratory work is given a year or two after the lectures, or that it is omitted altogether. If the book is used in conjunction with the usual course of lectures to begin- ners, as it is hoped that it may be, topics will naturally be selected in the same general order as that followed in the lectures or text-book. The discussion of special topics, such as crystalliza- tion, filtration, distillation, distillation under diminished pressure, extraction, etc., has been given in connection with preparations when their use is required. Frequent references to these discussions are given elsewhere, and they may also be readily found by means of the index. The author wishes to acknowledge his indebtedness to the somewhat similar works of L,evy, Gettermann, Krdmann, and H. Fischer for many suggestions ; also to a little book by Drs. A. A. Noyes and S. P. Mulliken on the "Class Reactions of Organic Substances", for some suggestions in writing the chapter on the qualita. tive examination of organic substances. He also de- sires to express his thanks to Mr. W. K. Burk, who pre- pared the drawings for the book, and to Mr. J. J. Kess- VI PREFACE. ler, Jr., who has tested many of the directions for prep- arations in the laboratory. I wish also to express my sincere thanks to Dr. J. Bishop Tingle, who has read carefully all of the proofs, and has made many valuable suggestions. OF CONTENTS. CHAPTER L ACIDS i 1. Isovaleric acid from amyl alcohol 12 2. Propionic and butyric acids from dipropylketone 18 3. Camphoric acid from camphor 20 4. Benzoic acid from benzyl chloride 23 5. Nitrobenzoic acids from toluene by nitration and oxida- tion 24 6. Succinic acid from ethylene bromide through the cy- anide 32 7 . Malonic ester from chloracetic acid 34 8. Mandelic acid from benzaldehyde through the cyanhy- drin 37 9. Paratoluic acid from paratoluidine through tolunitrile- 42 10. Acetacetic ester by condensation 44 n. Diacetylsuccinic ester from acetacetic ester 51 12. Succinylo-succinic ester 53 13. Hydrocinnamic acid from acetacetic ester and benzyl chloride ; benzyl acetone 55 14. Cinnamic acid ; Perkin's synthesis 58 15. Cinnamic acid from benzaldehyde through benzylidene acetone 59 16. Formic acid from oxalic acid 61 17. Stearic acid from tallow 63 18. Uric acid from urine 65 19. Levulinic acid from a hexose 67 CHAPTER IL DERIVATIVES OF ACIDS 70 20. Acetyl chloride from acetic acid and phosphorus tri- chloride 76 Vlll CONTENTS. 21. Acetic anhydride 78 22. Succinic anhydride from succinic acid with phosphorus oxychloride 79 23. Acetamide by heating ammonium acetate 80 24. Carbamide from phosgene and ammonia (Urea) 82 25. Phenyl sulphonamide from benzene 83 26. Phenyl benzoate, Schotten-Baumann's reaction 85 27. Acetanilide from aniline and acetic acid 86 28. Ethyl acetic ester from alcohol and acetic and sul- phuric acids ^ 87 29. Ethyl succinic ester from alcohol and succinic and sul- phuric acids 89 30. Diacetyl tartaric ethyl .ester, esterification with hydro- chloric acid and by the Schotten-Baumann reaction . . 89 31. Benzoic ethyl ester through benzoyl chlorid,e 92 32. ^-Brombutyric acid by bromination with bromine and phosphorus 93 33. Metanitrobenzoic acid by nitration of benzoic acid 95 34- Glycocoll from chloracetic acid 97 35. Anthranilic acid from phthalic anhydride through phthalamidic acid 99 36. Salicylic acid ; Kolbe's synthesis 101 37. Hydrocinnamic acid by reduction of cinnamic acid 103 CHAPTER III. HALOGEN COMPOUNDS 105 38. Methyl iodide from methyl alcohol, phosphorus and iodine 108 39. Ethyl bromide from alcohol, sulphuric acid and potas- sium bromide 109 40. Paradibrombenzene by direct bromiuation in 41. Benzyl chloride from toluene 112 42. Parabromtoluene from paratoluidine, Sandmeyer's re- action 114 43. Ethylene bromide from ethylene and bromine < 117 44. Chloroform from acetone and calcium hypochlorite 119 CONTENTS. IX CHAPTER IV. NITRO COMPOUNDS 121 45. Metadinitrobenzene by direct nitration 123 46. Metanitrotoluene from paratoluidine 124 47- #-Nitronaphtylamine 127 48. Orthonitroparatoluidine by direct nitration of toluidine 128 CHAPTER V. AMINES * 130 49. Aniline by reduction of nitrobenzene 133 50. Orthonitroparatoluidine from toluene through the dini- tro compound by reduction with ammonium sulphide 135 51. Paradiaminobenzene from acetanilide 136 52. Diethylamine from aniline and ethyl bromide through paranitrosodiethy 1 amine 138 53. Isopropyl aniiue by reduction of acetoxime 140 54- Gtf-Phenylethylamine from benzoyl chloride through benzyl cyanide 142 55. Benzyl amine 144 CHAPTER VI. HYDRAZO, Azo, DIAZO COMPOUNDS, ETC 148 56. Hydrazobenzene 153 57 . Azobenzene 154 58. Aminoazobenzene 1 55 59. Sulphobenzene-azo-fi-naphtylamine 157 60. Diazobenzene chloride 159 61. Phenyl hydrazine by reduction of diazobenzene with stannous chloride 160 62. Glucosazone 162 CHAPTER VII. ALCOHOLS AND PHENOLS 164 63. Ethylene glycol 166 64. Methylphenylcarbinol by reduction of acetophenone. 167 65. Paracresol from paratoluidine, Griess' reaction 168 66. Hydroquinone from aniline 170 X CONTENTS. 67. Alizarin from anthraquinone 172 68. Allyl alcohol from glycerol 175 69. Benzyl alcohol from benzaldehyde 176 CHAPTER VIIL ALDEHYDES, KETONES, AND THEIR DERIVATIVES 178 70. Acetaldehyde 181 71. Benzophenone from benzoyl chloride, benzene, and aluminium chloride 184 72. Benzaldehyde from benzyl chloride 187 73- Benzoin ; condensation by potassium cyanide 188 74. Anthraquinone by oxidation of anthracene 190 75- Phenyl hydrazone of acetophenone 191 76. Acetoxime 192 77- Semicarbazone of acetone 193 78. Furfural from a pentosan 196 CHAPTER IX. SULPHONIC ACIDS AND SULPHINE COMPOUNDS 198 79- Sulphanilic acid 200 80. Ortho- and paratoluene sulphonamides from toluene- .. 201 81. Trimethyl sulphine iodide 203 CHAPTER X. HYDROCARBONS 205 82. Benzene from benzoic acid 209 83. Paraxylene from parabromtoluene, methyl iodide and sodium 209 84. Triphenylmethane Friedel and Craft's synthesis 210 85. Cymene from camphor 212 86. Diphenyl from benzene by heat 213 87. Diphenylmethane from benzophenone 214 88. Anthracene from alizarin 215 CHAPTER XL MISCELLANEOUS COMPOUNDS 217 89. Quinoline Skraup's synthesis 217 CONTENTS. XI go. Phenol phthalein 2l8 91. Collidindicarboxyllic ethyl ester 220 92. Antipyrine 222 93. Thiophen 22 4 94. Orthobenzoylbenzoic acid 22 5 95. Phenyl cyanide 22 7 96. Zinc ethyl 228 CHAPTER XIL Qualitative examination of organic compounds 231 Reagents 2 4 Acids* I. Oxidation of Alcohols, Aldehydes, Ketones, and Hydrocarbons. The oxidation is usually effected by a mixture of potassium pyrochromate, sulphuric acid, and water, by dilute nitric acid, or by potassium permanga- nate in alkaline solution. With the chromic acid mixture the first product of the oxidation of an alcohol is probably an aldehyde or ketone. In the case of ethyl alcohol the aldehyde is so volatile as to escape rapidly as soon as formed and the method cannot be practically used for the preparation of acetic acid. With some of the higher alcohols of the same series the acid which is formed by the oxidation of a part of the alcohol combines with another portion of the alcohol to form an ester. The continued action of the oxidizing mixture may saponify the ester and complete the oxida- tion of the alcohol, but it is sometimes better to moder- ate its action so that the ester is the chief product of the oxidation and to secure the acid by the saponification of the latter (isovaleric acid). The oxidation of open chain ketones and of secondary alcohols can give rise to the formation of acids only by separating the molecule into two parts. The carbonyl of the ketone usually, but not always, goes with the 2 ORGANIC CHEMISTRY. smaller part. There may result a single acid, as in the case of methyl ethyl ketone (2-butanone) , or two acids, as with dipropyl ketone (^-heptanone) or propyl methyl ketone (2-pentanone) . In the latter case, for purposes of inves- tigation, the separation of homologous fatty acids becomes important. This can be effected by distilling an aqueous solution of the acids. The acid of higher molecular weight passes over first with the water vapor, apparently because it is less soluble in water. By preparing silver salts of the acids in the first and last portions of the distillate the composition of the acids formed can be established. (See 2, p. 18, separation of propionic and butyric acids) . The oxidation of cyclic ketones, and in some cases of other cyclic compounds, gives rise to the formation of bi-basic acids (camphoric acid). In the benzene series, side chains consisting of alkyl (CH 3 , C 2 H 6 , etc.) or other groups in which a carbon atom is combined directly with the benzene nucleus, can be oxidized to carboxyl. In the case of hydrocar- bons, the oxidation is usually effected with difficulty, partly owing to their insolubility in the oxidizing agents employed. On this account it is sometimes advisable to prepare, at first, a halogen derivative having the hal- ogen in the side chain (Baeyer : Oxidation of paraxylene, Ann. Chem. (L,iebig) , 245, 138 ; benzoicacid, 4 p. 23.) II. Saponification of Cyanides. The cyanides of or- ganic radicals, or "nitriles" of acids, may be obtained from halogen derivatives of hydrocarbons, salts of acid sulphuric esters of alcohols, or salts of sulphonic acids by treating with potassium cyanide. The last two ACIDS. 3 cases are applicable only when the cyanide formed can be distilled from the dry mixture without decomposi- tion. Nef has shown that potassium cyanide has the struc- ture K N=C, and the reaction probably takes place in two stages : K N=C + RC1 = K N=C<^ ! =NEEEC R+KC1. A small amount of an isocyanide is formed at the same time, the group N = C taking the place of the halogen or acid group of the organic compound. Cyanhydrines, which by saponification give tf-hy- droxy acids, can be prepared by treating aldehydes or ketoues with hydrocyanic acid, best in the nascent state: R R OH V=0+HCN = V/ . R' R' X CN From aromatic amines cyanides can be obtained by treating the diazo compound with cuprous cyanide. (Sandmeyer.) R NH a HCl + HNO a = R N=N+ 2 H 2 O, I Cl 2R N=N+CuC a N a = 2R CN+CU.C1,. Cl The cuprous cyanide for the reaction is prepared from copper sulphate. CuSO 4 + 2KCN = Cu(CN) a + K a SO 4 , 2 Cu(CN) a = Cu a (CN) a + (CN ).. 4 ORGANIC CHEMISTRY. The saponification of cyanides is usually effected either by the action of an aqueous or alcoholic solution of potassium, sodium, or barium hydroxide, or by the action of hydrochloric or sulphuric acid. An amide of the organic acid is probably always an intermediate product of the saponification and, in some cases, the conversion of the cyanide into an amide and the conver- sion of the latter into the acid may, with advantage, be carried out in two stages and by means of different agents. O R C = N + H a O = R C NH 3 , O O / S R C NH a + KOH = RC OK + NH 3 , or O O / / R C NH a +H a O + HCl = RC OH + NH 4 C1. III. Condensation. By condensation, in general, is meant the formation of a compound from two others with the elimination of water, alcohol, ammonia, hydro- chloric acid, or two halogen atoms. 1 Methods of conden- sation have been especially useful in the synthesis of acetacetic ester and its derivatives, cinnamic acid, and of many other compounds in which the same principles have been applied. 1 Some authors use the term condensation exclusively as applied to reac- tions in which carbon atoms unite, and especially with the elimination of water or alcohol, but there appears to be no logical reason for such a restric- tion in its use. ACIDS. 5 In the case of acetacetic ester the condensation ap- pears to take place as follows : CH 3 COjOC 2 H B + H;CH 3 C0 2 C 3 H 6 = CH 8 COCH 3 CO 3 C 3 H 6 + C 2 H 6 OH. The researches of Claisen indicate, however, that the action consists, at first, in the addition of sodium ethyl- ate, formed from a trace of alcohol which is always pres- ent in acetic ester, to the ester, thus : ^O /ONa CH 3 Cf + NaOC 2 H B = CH 3 C OC 2 H 6 . X OC 3 H 6 \OC 2 H 5 The addition product then condenses with a second molecule of acetic ester thus : /ONa CH 8 C !OC 2 H; H 3 JCH.CO 2 C 3 H 5 = \|OC 2 H 6 ONa / CH 8 C = CH.CO 2 C 3 H 5 + 2 C 2 H 5 OH. According to this view, on the addition of an acid a OH / compound of the formula CH 3 C= CH CO 2 C 3 H 6 would be liberated. A very large amount of work has been done for the purpose of discovering whether acet- acetic ester and similar bodies have the " enol" (un- saturated alcoholic) or ketone structure. In spite of this, those who have studied the subject most carefully have not, apparently, come to any general agreement. It would seem that bodies of this character pass very ORGANIC CHEMISTRY. readily from one form into the other and that while, in some cases, the bodies in question may consist exclu- sively of the one or other form, in others they are, in all probability, mixtures of the two forms. Therefore the bodies in question may react in one or the other form or in both, according to the reagents used, one form passing over into the other, as the one or other form disappears in the progress of the reaction. Very closely analogous to the preparation of acet- acetic acid is the preparation of succinylosuccinic ester by the condensation of succinic ester. C0 2 C,H 6 NaO CO 2 C 2 H fi | \ i or H j I Na C Ci C ONa \ ^ | ! S 11 * ; C C0 2 C 2 H 5 | CO Q C 2 H 5 Succinic ester -f Sodium salt of succinyl- sodium ethylate. osuccinic ester. By the action of sodium ethylate on mixtures of esters or of esters and ketonesor aldehydes, many similar con- densations may be effected. In every case one ester group, after adding sodium ethylate, condenses with an ethyl or methylene group which is adjacent to the carbonyl of a ketone or of an ester group. That the methin group (CH) is not susceptible to this sort of condensation is ACIDS. 7 one of the proofs for Claisen's view, referred to above (Ber. d. chem. Ges., 20, 651 ; 21, 1154). Acetacetic ester and similar compounds which con- tain a methylene or methin group between two carbonyl or ester groups give sodium salts when treated with sodium ethylate. In some cases cyanogen or other groups may have the same effect as carbonyl. Accord- ing to the views of some, in these sodium salts the sodium is combined with oxygen (" enol" form, see above) ; according to others it is combined with carbon (ketone form). When these sodium', silver, or copper salts of acetacetic ester, malonic ester, and similar compounds are treated with alkyl iodides, acid chlorides, or other halogen derivatives, compounds are formed in which the alkyl or other groups are sometimes com- bined with carbon and sometimes with oxygen. ONa / CH 3 C=CH C0 2 C,H 5 +CH 3 I = ONa CH 3 / / CH 3 CI CH C0 2 C 2 H 6 = CH 3 / CH 3 CO CH CO 2 C 2 H 6 +NaI, Na / or CH 3 COCH CO 2 C 2 H 6 +CH 3 I = CH 3 / CH 3 CO CH C0 1 C i H.+NaI, ORGANIC CHEMISTRY. Ocu CH 3 C=CH C0 2 C 2 H 5 +CH S COC1 = O COCH S X CH 3 C=CH CO.C.H.+CUC1. 1 (See Nef : Ann. Chem. (Liebig), 266, 103,. no, and 287, 270.) With alkyl iodides, compounds containing the alkyl combined with carbon are almost exclusively formed. This method has been of very great value in obtain- ing derivatives of acetacetic ester, CH 3 COCH Q CO 2 C 2 H 6 , OO O T-T malonic ester, CH 2 and other compounds. Acetacetic acid and almost all other /?-ketonic acids are extremely unstable in the free state. Hence, if the esters of these acids are saponified, decomposition products are usually obtained, instead of the free acid. These products vary according to the nature of the ester and the means used for its saponification. In general, saponification with acids causes decomposition with loss of carbon di- oxide and formation of a ketone (ketonic decomposi- tion) : CH 3 COCH 2 CO 2 C 2 H & + H 2 SO 4 + H 2 O = Acetacetic ester. CH 3 COCH 8 + C 2 H 6 OH + H 2 SO 4 + CO 2 . Acetone. (See also Baeyer : Ann. Chem. (Liebig), 278, 90, for the saponification of succinylosuccinic ester.) i In this case "cu " is used to represent an equivalent instead of an atom of copper. ACIDS. 9 Saponification with strong bases, on the other hand, tends to favor the formation of acids (acid decomposi- tion). CH 3 COCH a C0 8 C a H 5 +2KOH = CH 3 CO a K + CH 3 CO a K + C 2 H 6 OH. Free malonic acid and its derivatives, that is, all compounds having two carboxyls combined with the same carbon atom, although stable at ordinary tempera- tures, are decomposed when heated to i5o-2oo, and many of them, also, when heated with moderately strong, not concentrated, sulphuric acid. The value of acet- acetic ester for synthetic purposes is lessened because of the difficulty of securing a clean " acid decomposi- tion" and, since the same product may usually be ob- tained by the use of malonic ester, the latter is now more frequently used in syntheses. Another method of condensation used for the prepara- tion of acids, known as Perkin's synthesis (Perkin : Ann. Chem. (Liebig), 147, 230; Ber. d. chem. Ges., 8, T 599 I J SD - d. Chem., ^77, 789; Tiemann, Herzfeld : Ber. d. chem. Ges., 10, 63), consists in heating a mix- ture of an aldehyde, a sodium salt, and acetic anhy- dride. One of the most common illustrations is the syn- thesis of cinnamic acid, which appears to take place as follows : C 6 H 5 CHjO + H a jCHCO a Na = Benzaldehyde. C 6 H 6 CH=CHCO a Na + H 9 O. Sodium cinnatnate. 10 ORGANIC CHEMISTRY. The reaction has been shown to take place in two stages and consists, first, in an addition of the sodium salt to the aldehyde group : .O /OH C 6 H 6 C^ + HCH 2 C0 2 Na = C 6 H 6 C CH 2 CO 2 Na. X H \H This addition is followed, under the influence of the acetic anhydride, by loss of water. The addition always takes place with the methyl, methylene or me- thin group adjacent to the carboxyl. Unlike the acet- acetic ester syntheses, the addition may take place with a methin group as well as with methyl and methylene groups, but in that case there can be no loss of water, and a hydroxy acid is formed. This is one of the most important proofs that the course of the reaction is as given. Historically this reaction was first used in the synthesis of cumarin by Perkin. Later, cinnamic acid and its de- rivatives became of especial interest because of their use by Baeyer in the synthesis of indigo. Knoevenagel (Ber. d. chem. Ges., 27, 2345 : Ann. chem. (L,iebig),28i, 104) has recently discovered a new method of synthesis in which formaldehyde is used, and condensation takes place under the influence of some organic base. The mechanism of the reaction is not clearly understood. A somewhat similar condensation, but one which does not lead to the formation of an acid, is that of formalde- hyde, with derivatives of benzene and its homologues, under the influence of concentrated sulphuric acid. ACIDS. I'Yl NO 2C e H B N0 2 + CH 2 O = C 6 H 4 CH 2 C 6 H 4 N0 2 +H 2 O. (Schopff : Ber. d. chem. Ges., 27, 2321.) IV. Decomposition of Bibasic Acids. This method of preparation is used in connection with the synthesis by condensation of derivatives of malonic acid. In the case of acids where the two carboxyl groups are not com- bined with the same carbon atom, a clean decomposition cannot usually be effected by heat alone. In some cases, however, one of the carboxyls may be removed by heating the barium salt of a bibasic acid with sodium methylate (Mai: Ber. d. chem. Ges., 22, 2136). The decomposition of oxalic acid may be considered as a special case under this head : CO 2 H | = HC0 2 H + C0 2 . C0 2 H The decomposition effected by heat alone is unsatis- factory in this case, also, and heating with glycerol is practically used. The glycerol appears to form an ester, OOTTO C 8 H 6 CHCH a CH a OH, the valeric acid obtained from it will consist mainly of the acid cor- responding to this formula. Fusel oil contains, how- ever, 10 to 20 per cent, of what is supposed to be a CH 3 CH mixture of the 2-methyl butanols, ;CHCH 2 OH, CH, and these will, of course, give the corresponding acids by oxidation. Hence, the valeric acid prepared from fusel oil, is probably a mixture of at least two or three chemical individuals. The perfectly pure iso- valeric acid (3-methyl butanoic acid) can be obtained by conversion of the acid into the barium salt, crystal- lizing the latter from water and then separating the acid from the pure salt. Pure isovaleric acid is a colorless liquid with an un- pleasant odor. It boils at 176.3 and has a specific gravity of 0.931 at 20. It dissolves in 23.6 parts of water at 20, but the addition of soluble salts causes most of it to separate from the solution. The chromic acid mixture oxidizes it to acetic acid and carbon diox- ide. 1 8 ORGANIC CHEMISTRY. The barium salt crystallizes in small prisms or thin leaflets. The silver salt crystallizes in leaflets soluble in 400 parts of water at 20, or in 204 parts of water at 80. The salts, when thrown on water, rotate rapidly. This is characteristic of the salts of many of the higher fatty acids. The most serious objection to this preparation is the very unpleasant odor accompanying it. The operations should be conducted under a hood as far as possible, and care should be taken to avoid contact of the valeric acid with the hands or clothing. 2. Oxidation of a Ketone Separation of Two Fatty Acids. Propionic and butyric acids, C 2 H B CO,H and C S H 7 CO 3 H (propanoic and butanoic acids) . Literature. Papow : Ann. Chem. (Liebig), 145, 283; 161, 291; lyiebig: Ibid., 71.355; Fitz : Ber. d. chem. Ges., n, 46; Hecht: Ann. Chem. (Liebig), 209, 319; Erlenmeyer u. Hill: Ibid., 160, 296; Baeyer : Ibid., 278, 101. 10 grams normal butyric acid (butanoic acid) . 25 grams quicklime. 6 grams dipropylketone (4 heptanon). 25 grams potassium pyrochromate. 1 20 cc. water. 20 cc. concentrated sulphuric acid. Weigh in a small porcelain dish 10 grams of normal butyric acid. Add carefully, taking care that the mix- ture does not become so hot as to volatilize any appreci- able amount of the acid, 25 grams of powdered quick- lime. Mix thoroughly and powder in a mortar. Place the mixture in a 50 cc. flask, clamp the latter in a hori- ACIDS. 19 zontal position, and connect it by means of perforated cork stoppers and a bent glass tube with a small con- denser. Distil by heating carefully with a free flame. Collect the distillate in a small flask, add a little dry potassium carbonate to remove a small amount of acid and water which are present, weigh, pour off into a 500 cc. flask and weigh again to determine the amount of crude ketone formed. For six grams of the ketone add a cooled mixture of 25 grams potassium pyrochromate, 20 cc. concentrated sulphuric acid and 120 cc. of water, using more or less, according to the amount of the ketone. Boil for three hours on a thin asbestos plate, with a reversed condenser (Fig. i). Transfer the mix- ture to a 200 cc. distilling bulb and distil in a current of steam (Fig. 2), collecting the distillate in successive por- tions of 10, 25, 50, and 100 cc. Prepare, separately, cal- cium salts of the acid in the first and last portions by boiling for a short time with a small quantity of pure calcium carbonate, and filtering. Concentrate each solution to 10 cc. or less, and add 5 cc. of a ten per cent, solution of silver nitrate. Filter off the silver salt, best on a small Witt plate (Fig. 5.), wash, dry, and deter- mine the per cent, of silver in each salt by careful ignition in a porcelain crucible. The oxidation gives, in this case, a mixture of pro- pionic and butyric acids. On distilling the mixture in a current of steam the butyric acid, which is less solu- ble, comes over mainly in the first portion, while the propionic acid comes over afterwards. A single distil- lation as directed will usually, when but two acids are 2O ORGANIC CHEMISTRY. present, give a sufficient separation so that the analyses of the silver salts leave no question as to the composi- tion of the acids. Butyric acid boils at 162, and has a specific gravity of 0.978 at o. Propionic acid boils at 141, and has a spe- cific gravity of 1.013 at o. 100 parts of water dissolve 0.48 parts of normal silver butyrate and 0.836 parts of silver propionate at 20. 3. Oxidation of a Cyclic Ketone. Camphoric acid, Literature. Kosegarten : Dissertation, Gottingen, 1785 ; Lau- rent: Ann. Chem. (Laebig), 22, 135; Wreden : Ibid., 163, 323; Maissen : Ber. d. chem. Ges., 13, 1873 ; Helle : Dissertation, Bonn, 1893 ; Noyes : Am. Chem. J., 16, 501 ; Aschan : Structur und Stereochemische Studien in der Campher Gruppe, Hel- singfors, 1895, p. 141. /CH, 50 grams camphor, C 8 H ' X CO 300 cc. nitric acid (1.42). 200 cc. water. Place in a one liter flask 50 grams of camphor, 200 cc. of water, and 300 cc. of nitric acid (sp. gr. 1,42). Close the mouth of the flask with a tube of the form shown in the cut, filled with water. The tube is easily made by taking a tube 40 cm. long, which will pass easily into the neck of the flask, seal- ing it at one end, and blowing a small bulb at about 10 cm. from the sealed end. Heat the mixture on a boil- ACIDS. 21 Fig. 4 . ing water-bath or a steam-bath for seventy- two hours. Cool, filter off the camphoric acid with the pump on a Hirsch funnel or a Witt's plate, using an " S. & S." hardened filter (Fig. 5). After sucking away the mother-liquors, stop the pump, add enough water to barely cover the acid, and suck off again. In all cases where the substance to be washed is appreciably soluble this method should be employed, as bodies may, in this way, be effectively washed by the use of a much smaller quantity of the sol- vent than if the pump is allowed to act while the solvent is poured over the precipitate. By washing three or four times in this manner the nitric acid will be almost com- pletely removed, and the camphoric acid, after drying, will be suffi- ciently pure for many purposes, and especially for the preparation of the anhydride, as the latter is easily purified by crystallization from alco- hol . The acid will , however, contain some unchanged camphor and, probably, a small amount of camphoraminic acid, C 8 H 14 or [] D -|- 47.8. loo parts of water dissolve 0.625 parts of the acid at 12, and 8 to 10 parts at 100. On heating alone, or with acetyl chloride, or acetic anhydride, it is OO converted into the anhydride, C 8 H ]4 <^J:J>O . The latter is converted by ammonia into the ammonium salt of <*-camphoraminic acid, C 8 H 14 <^pQ -^TT , which on CO heating gives an imide C.H i4 <^Q>NH. This on treatment with caustic soda gives the sodium salt of /?-camphoraminic acid, QS^^^PQXT.,?- . Hence the two carboxyls of camphoric acid are not symmetrically placed in the molecule. ACIDS. 23 4. Oxidation of a Homologue of Benzene with a Halogen Atom in the Side Chain. Benzole acid, C.H.CO.H. Literature. Grimaux, Hauth : Bul.soc.chim., 7, 100 ; Lunge : Ber. d. chem. Ges., 10, 1275 ; Carius : Ann. Chem. (Liebig), 148, 51 and 59 ; Wagner : Jsb. d. Chem., 1880, 1289 ; V. Meyer; Ber. d. chem. Ges., 24, 4251 ; Saiidmeyer : Ibid., 17, 2653. 20 grams benzyl chloride. 46 grams nitric acid (sp. gr. 1.42). 55 grams water. Put into a 300 cc. flask with a narrow neck, from which the lip has been cut off, so as to leave the neck straight to the top, 20 grams of benzyl chloride, 46 grams (32 cc.) of concentrated nitric acid, and 55 cc. of water. Slip over the neck of the flask a short piece of rub- ber tubing, and pass through this the tube of an upright condenser of such size as to just pass easily into the neck of the flask (see 32). By this means a tight joint is formed, and at the same time the vapors scarcely come in contact with the rubber. Place the flask on a wire gauze and boil gently for 2 to 3 hours, or until the oxides of nitrogen nearly disappear within the flask, and the benzoic acid formed largely sinks to the bottom of the liquid. There is some tendency for the liquid to boil explosively, but there is less trouble from this source if a round-bottomed flask is used, and this is heated directly over a small flame which is brought close to the wire gauze, than if the flask is heated on a sand bath or on an asbestos paper. Cool, filter on a plate, suck off the mother-liquors, 24 ORGANIC CHEMISTRY. stop the pump, moisten thoroughly with water and suck off again. Dissolve the benzoic acid in 70 to 80 cc. of sodium hydroxide (10 per cent.), added to alkaline reac- tion, filter on a plain filter, or pour off from any benzyl chloride which remains undissolved, put the solution in a flask or large beaker and pass through it a rapid current of steam till the vapors no longer smell of ben- zyl chloride. Precipitate the benzoic acid again by adding 1 8 to 20 cc. of concentrated hydrochloric acid. Cool thoroughly, filter on a plate, and wash once. Crys- tallize from a mixture of 30 cc. of alcohol with 10 to 15 cc. of water. The benzoic acid prepared in this way retains a little chlorbenzoic acid from which it appears to be nearly or quite impossible to free it. This can be detected by heating a little of the acid, mixed with sodium carbon- ate, on platinum foil till it chars, adding a little potas- sium nitrate and heating again till white, dissolving the residue in water and dilute nitric acid, and adding silver nitrate. Yield 13 to 15 grams. Benzoic acid crystallizes in needles or leaflets which melt at 121.4. It boils at 249. TOO parts water dis- solve 0.27 part of the acid at 18, and 2.19 parts at 75. An impure acid is more easily soluble. It is soluble in about 3 parts of strong alcohol at 15. It is easily vola- tile with water vapor. The vapors of the acid produce a coughing sensation. 5. Oxidation of a Side Chain of a Hydrocarbon De- rivative. Ortho- and para-nitrobenzoic acids, ACIDS. 25 Literature. Beilstein : Ann. Chem. (Liebig), 133, 41 ; 137, 302 ; Hofmann : Ibid., 97 207 ; Weith : Ber. d. chem. Ges., 7, 1057 ; Monnet, Reverdin, Nolting : Ibid., 12, 443 ; Nolting, Witt : Ibid., 18, 1336. 40 grams toluene. 50 cc. sulphuric acid (1.84). 30 cc. nitric acid (1.42). Place in a 300 cc. flask, 40 grams (46 cc.) of toluene and add in small portions a cooled mixture of 50 cc. of concentrated sulphuric acid, and 30 cc. of nitric acid (1.42). Shake vigorously and cool after each addition, taking care that the temperature does not rise above 30. After the acid has all been added, shake vigorously for ten minutes, keeping the temperature down as before. Pour into about 700 cc. of water. The nitrotoluene will now sink to the bottom. Separate from the acid liquid with a separatory funnel, and wash by shaking the nitrotoluene again with about 100 cc. water. In this and all similar cases where a heavy liquid is to be separated from water, it is best to use a flask or separatory funnel of such size that the mixture will fill it nearly to the top, as otherwise a considerable amount of the heavy liquid may remain floating on top of the water. Separate the nitrotoluene as completely as possible from the water, put it in a small flask, add 10 grams of fused, granulated calcium chloride, and warm on a water-bath with the flask covered with a watch-glass for half an hour, or allow it to stand over night. Pour the nitrotoluene off 26 ORGANIC CHEMISTRY. into a distilling bulb. Distil, using a glass tube as a condenser (see Fig. 3). The portion distilling below 200 consists principally of unchanged toluene, and may be saved. That distilling between 2oo-24O consists chiefly of ortho- and paranitro toluene, while that boiling above 250 consists chiefly of dinitrotoluene. Ortho- nitrotoluene boils at 220 and melts at 10.5. Para- nitrotoluene boils at 239 and melts at 54. The two can be partially separated by fractional distillation, and the para compound can be obtained pure by crystallization from alcohol. For the remainder of this preparation the mixture boiling from 2OO-24O may be used. 15 grams mixed nitrotoluenes. 100 cc. water. 10 cc. sodium hydroxide (10 per cent). 35 grams potassium permanganate. 350 cc. water. Arrange a one liter flask with an up- right condenser, a bent thistle tube, and a bent tube to convey steam to the bot- tom of the flask, as indicated in the fig- ure. (See Fig. 7). Place in the flask 15 grams of the mixed nitrotoluenes, 100 cc. of water, and 10 cc. of a 10 per cent, solution of sodium hy- droxide. Add about 50 cc. of a warm 10 per cent, solution of potassium per- manganate. Pass in a current of steam rapidly till the solution boils, and then Fig. 7 . just fast enough to keep the contents of ACIDS. 27 the flask agitated, and so that a small amount of steam condenses above. Add more of the permanganate solu- tion at frequent intervals till 35 grams of the salt in all have been added. Continue the current of steam until the pink color of the permanganate disappears, or till the drops of nitrotoluene cease to appear in the condenser. If unreduced permanganate is still present, add a few drops of alcohol, and shake to reduce it. Filter hot, from the oxides of manganese, on a filter plate or Hirsch funnel, and wash twice with water. Concentrate the filtrate to about 40 cc. , and precipitate the mixed ortho- and parani- trobenzoic acids with 25 cc. of concentrated hydrochloric acid. Cool very thoroughly, filter on a -plate, and wash twice with a very small amount of cold water, sucking off the mother- liquors thoroughly each time (see 3 p. 21). Convert into the barium salts by boiling with about 12 grams of barium carbonate and 200 cc. of water. Filter hot and cool the filtrate. A considerable portion of the ba- rium salt of the para acid will separate. Filter, wash once with cold water and concentrate the filtrate and washings to a very small volume. Cool quickly, and filter at once on a plate. Moisten the residue several times with a small amount of cold water and suck off. Concentrate the filtrate and washings, and crystallize the ortho salt by allowing the cold, concentrated solution to stand for some time. Recrystallize both the ortho and para salts from hot water, saving the mother-liquors and working them up in such a manner as to secure as large an amount as possi- ble of each salt in a pure condition. The separation of two substances by crystallization is 28 ORGANIC CHEMISTRY. a problem which frequently presents itself in organic chemistry, and it frequently requires very careful work and good judgment to secure both substances in pure condition without serious loss of material. As the substance which is present in least amount, or which is most easily soluble, is liable to form supersaturated solutions, it is usually advisable to filter off a substance which has crystallized as soon as its separation from the solution appears to be practically complete. The separa- tion can frequently be hastened by vigorous stirring, and by the addition of a fragment of the pure substance, when crystals are slow in starting. Occasionally, how- ever, a substance may form crystals sufficiently large to be separated mechanically from others with which they are mixed. In such cases the crystallizations must be allowed to proceed slowly and undisturbed, and it may be well to allow the solution to evaporate slowly at ordinary temperatures, or in vacua over sulphuric acid. L,arge crystals of the barium salt of orthonitro- benzoic acid may be obtained in this way. Crusts which separate on the walls of a dish or beaker during evaporation, usually consist of a mixture, and should be brought back into the solution and redis- solved by heating before the latter is cooled for crystal- lization. In using a solvent, a very common mistake is to use too large an amount. A small amount should always be added at first, unless the properties of the substance are familiar, and then more, if the substance cannot be brought into solution. ACIDS. 29 With substances which separate very easily on cool- ing the solution, the opposite mistake may be made, if the solution requires filtration. In such cases, the sub- stance should be taken only in such amount as will dis- solve very easily in the amount of the solvent used, and care must be taken to prevent the crystallization of the substance on the filter, either by the use of a plate, (not a Hirsch funnel) , and pouring only as fast as the solution runs through the filter, or by the use of a hot water fun- nel. The latter is rarely necessary, if the chemist has acquired the necessary experience, except in cases where a precipitate clogs the filter badly. When alcohol is used as a solvent, the yield of crys- tals may, sometimes, be increased by adding some water to the solution before it cools. When the impurities are soluble in dilute alcohol, this may be used with advan- tage instead of pure alcohol to wash the crystals. It should be remembered that strong alcohol is not a suitable solvent for some acids and some nitro-phenols because of the ease with which they form esters. Crystallization is the most valuble means in the hands of the chemist for obtaining pure substances. When it can be applied, it almost always gives purer substances than fractional distillation. In working with new sub- stances, success very often depends largely on the choice and use of proper solvents, and it is a matter to which the beginner should give very careful attention. In working with new bodies valuable hints can almost always be obtained by learning from text-books or chemical journals the conduct of closely related bodies which have been previously known. 30 ORGANIC CHEMISTRY. Orthonitrobenzoic acid crystallizes in colorless, tri- clinic prisms, which have a sweet taste, melt at 147, and dissolve in 164 parts of water at 16.5. Paranitrobenzoic acid crystallizes in yellow leaflets, which melt at 240, and dissolve in 1200 parts of water at 17, or in 140 parts at 100. The barium salt of the ortho acid crystallizes with 3 molecules of water, in yellow, triclinic crystals, which are easily soluble in water. The barium salt of the para acid crystallizes with 5 molecules of water, in yellow, monoclinic prisms, soluble in 250 parts of cold, and 8 parts of hot water. The purity of solid substances is, in many cases, most easily tested by means of the melting-point. For this purpose the substance must be perfectly dry. The drying can be effected by allowing the body to lie for a sufficient length of time on filter paper, or on clean por- ous porcelain, best over sulphuric acid in vacua. A lot of capillary tubes for the determination of melting points may be prepared by taking a soft glass tube with not too thin walls, 4 to 5 mm. in external diameter, and drawing it out as indicated above. (See Fig. 8.) The tube is then sealed off near each bulb, and the closed tubes kept till needed. For use, the bulb is cut in two by scratching with a file and breaking. The finely powdered substance is put into the wide end of ACIDS. 31 the tube and shaken down, or pushed down to the point with a clean platinum wire. For a melting-point bath the best for general use is a round-bottomed, 75 cc. flask, with a rather long neck. In the mouth is placed a stopper, perfo- rated so that the thermometer will pass easily through it, and be held in place by a small wooden wedge, e.g., a match stick. Through the side of the cork passes a small platinum wire with loops, as indicated in the figure. (See Fig. 9.) If moistened with the sulphuric acid, the tube will adhere to the thermometer by capillary attraction, but such an arrangement is less se- cure, g. 9- The part of the capillary tube con- taining the substance should lie in contact with the bulb of the ther- mometer. The bath may be heated rapidly with a free flame till the tem- perature approaches the melting-point, and then very slowly. In case of bodies which decompose at or near their melting-points, the thermometer and the tube should be brought as quickly as possible, without danger Fig. 10. of breaking the thermometer, into the hot bath and the latter brought quickly to the melting- point. The result, in such cases, cannot be very accu- rate. When, as is usually the case, the stem of the ther- 32 ORGANIC CHEMISTRY. mometer is not immersed in the sulphuric acid to the point to which the mercury rises, a correction similar to that for boiling-points must be applied. (See i, p. 16.) In general, a sharp melting-point, within an interval of one degree, at most, is characteristic of a pure sub- stance, while impure substances melt indefinitely. 6, Preparation of a Cyanide and Acid from a Halo- gen Derivative of a Hydrocarbon. Succinic acid, CH, C0 2 H CH 3 CO a H. Literature. Simpson: Ann. Chem. (L,iebig), 118, 374; xax, 154; Nevole u. Tscherniak : Bui. soc. chim., 30, 101 ; Fau- connier : Ibid, 50, 214 ; Brown, Walker : Chem. News, 66, 91 ; Ann. Chem. (Iviebig), 261,115; Ljebig: Ibid, 70, 104, 363; Konig: Ber. d. chem. Ges., 15, 172. 50 grams ethylene bromide. 100 cc. alcohol. 34 grams potassium cyanide. 35 cc. water. 40 grams potassium hydroxide. 65 cc. concentrated hydrochloric acid. Place in a 300 cc. flask 50 grams of ethylene bromide and loo cc. of alcohol. Connect with an upright con- denser, heat to boiling on a water-bath, and drop into the solution slowly from a drop funnel placed in the top of the condenser, a solution of 34 grams of potassium cyanide in 35 cc. of water. After the solution has all been added, boil on the water-bath for an hour and a half. Cool, and pour off from the potassium bromide ACIDS. 33 into a flask containing 40 grams of solid potassium hydroxide, cooling, if necessary, to prevent too violent a reaction at first. Rinse the residue of potassium bro- mide twice with a small amount of alcohol, adding the rinsings to the main portion. Boil with an upright condenser for two hours. Pour the contents of the flask into a porcelain dish, and evaporate on the water-bath till the alcohol is entirely removed. Add fifty cc. of water, and 40 cc. of concentrated hydrochloric acid, and filter. To the filtrate add 25 cc. more of concentrated hydrochloric acid, cool very thoroughly, filter off the succinic acid, and crystallize it from hot water. The yield is poor. Succinic acid crystallizes from water in tabular crys- tals. It melts at 182. If heated above its melting- point, it is converted into the anhydride. 100 parts of water at o dissolve 2.8, at 20 6.9 parts, at 50 24.4 parts of the acid. 100 parts of alcohol at 12 dissolve 7.5 parts, and 100 parts of ether 1.26 parts. Kthylene cyanide is present in the above alcoholic so- lution and can be obtained from it as follows : Pour the solution off from the potassium bromide into a 300 cc. distilling bulb, rinse as before, and distil off as much of the alcohol as possible on the water-bath. Transfer to a 100 cc. bulb, fitted with a thermometer, capillary tube, and receiving bulb, as indicated in Fig. 12, p. 46. Distil on the water-bath under diminished pressure as long as alcohol or water comes over. Then change the receiver and distil carefully over a free flame, or in an oil bath, with the pressure as low as possible. 34 ORGANIC CHKMISTRY. Kthylene cyanide boils, under 10 mm. pressure at 147, under 760 mm. pressure at 26^-26^, with partial decomposition. It melts at 54, 7. Preparation of an Ester of a Bibasic Acid from a Halogen Derivative of an Acid. Malonic ester, Literature. Dessaignes : Ann. Chem. (L,iebig), 107, 251 ; Kolbe and Miiller: Ibid, 131, 348, 350; Finckelstein : Ibid, 133, 350; Conrad: Ibid, 204, 126; Claisen and Venable : Ibid, 218, 131. Kolbe and Miiller : J. Chem. Soc., 17, (1864) 109; Noyes : J. Am. Chem. Soc., 18, 1105 (1896). 50 grams monochloracetic acid. 45 grams acid sodium carbonate. TOO cc. water. 40 grams potassium cyanide. 100 cc. alcohol. 80 cc. concentrated sulphuric acid. Put 50 grams of monochloracetic acid into a porcelain dish 20 cm. in diameter. Add 100 cc. of water, and 45 grams of acid sodium carbonate. Warm, stirring with a thermometer, till a temperature of 5o-6o is reached, and the effervescence has ceased. Place the dish on a sheet of asbestos paper on a tripod, in a hood with a good draught. Add 40 grams of powdered potassium cya- nide, and stir vigorously with the thermometer. Warm only very gently till the reaction, which takes place with considerable evolution of heat and spontaneous boiling of the solution, is complete. Then raise the flame and evaporate rapidly, stirring constantly with the ACIDS. 35 thermometer till a temperature of 130 is reached. Dur- ing this part of the operation keep the window glass of the hood between the dish and the face, and cover the hand with a towel or glove to protect it from the par- ticles of the mixture which are thrown out. Remove the dish from the flame, and continue to stir till the mass is cold. Transfer at once to a 500 cc. flask, as the mass is very hygroscopic. Connect the flask with an upright condenser (seeip. 13). Add 20 cc. of alcohol and then, in small portions, through the condenser, a cooled mixture of 80 cc. of alcohol with 80 cc. of concentrated sulphuric acid. After each addition, mix the contents of the flask as thoroughly as possible by shaking. When all of the mixture has been added, shake till the whole is thor- oughly mixed, and then heat on the water-bath for an hour. Cool, add 150 cc. of cold water, and shake thor- oughly. Filter on a Hirsch funnel or plate, and suck the liquid through as completely as possible. Stop the pump, moisten the salt with ether; after a minute or so draw this through, and repeat twice. Transfer the con- tents of the filtering flask to a separatory funnel and draw off the salt solution below. Add a small amount of a strong solution of sodium carbonate, and shake carefully with the funnel open at the top to allow the carbon dioxide to escape. When enough of the solution has been added to neutralize the free acid, insert the stopper and shake more vigorously, holding the stopper firmly in place, and after each shaking turning the fun- nel bottom-side up and opening the stop-cock to re- lieve the pressure. Allow the two layers to separate as 36 ORGANIC CHEMISTRY. completely as possible, draw off the aqueous solution below, allowing it to run into the first acid solution. Transfer the ethereal solution of the malonic ester to a distilling bulb. Distil off the ether on a water-bath, using a condenser, then put in the mouth of the bulb a rubber stopper bearing a tube drawn out below to a fine capillary, which reaches nearly to the bottom of the bulb, and attach a second bulb to the side tube (see Fig. 12, p. 46, but omit the thermometer). Heat in the water- bath and reduce the pressure to 50 mm. , or less, for fifteen minutes. This method of drying substances which boil above 190 is usually quicker and more satisfactory than the use of calcium chloride or other drying agents. Malonic ester may also be dried with advantage by al- lowing it to stand in a crystallizing dish in a vacuum desiccator for twenty- four hours. After drying, distil with a thermometer and condens- ing tube (see i, p. 15) . Very little passes over below 190, and that boiling from i9o-2OO will be very nearly pure malonic ester. If a very pure ester is desired, it may be distilled again, and only the portion boiling within one degree of the true boiling-point taken. Yield, 45 grams. The sodium carbonate solution contains some of the acid ester. If this solution is added to the first acid solu- tion, the acid ester separates with some ether. The ethereal solution may be separated, the ether evaporated at a gentle heat, and the residue added to the contents of the flask, in which a second saponification of the cyanacetate is to be effected. This will increase the yield to 50 grams. ACIDS. 37 Malonic ester is a colorless liquid which boils at 198, and has a specific gravity of 1.061 at 15. It is decom- posed on heating to 150 with water, giving acetic ester, carbon dioxide, and alcohol. (For the conduct of ma- Ionic ester toward sodium ethylate and its use in syn- theses, see p. 8.) If it is desired to prepare malonic acid, after adding the potassium cyanide as directed above, continue to heat gently for half an hour, then add 120 cc. of a strong solution of sodium hydroxide (3 cc. = i gram NaOH), and continue to heat, replacing the water which evapo- rates, as long as the evolution of ammonia continues, usually about an hour. Add carefully 68 cc. of hydro- chloric acid (4 cc. = i gram HC1), and a solution of 70 grams of calcium chloride. Filter, wash with cold water, and dry at 100. The calcium malonate retains two molecules of water. To obtain the free acid the salt is decomposed by warming with the calculated amount of a strong solution of oxalic acid, filtering from the cal- cium oxalate, and evaporating to crystallization. Ma- lonic acid melts at 134 and dissolves in about two-thirds of its weight of water at 16. At 140- 150 it decom- poses into carbon dioxide and acetic acid, a reaction characteristic of acids having two carboxyls combined with one carbon atom. The calcium salt is almost insoluble in cold water. 8. Preparation of an o'-Hydroxy Acid from an Al- dehyde, through the Cyanhydrin. Mandelic acid, /OH C 6 H 5 C CO 2 H (phenethylolic acid). \H ' 38 ORGANIC CHEMISTRY. Literature. Winckler: Ann. Chetn. (Liebig), 18,310 ; Spiegel: Ber. d. chem. Ges., 14, 239; Engler, Wohrle : Ibid, 20, 2202; Wallach : Ann. Chem. (I^iebig), 193, 38; Luginin u. Naquet : Ibid, 139, 299 ; Miiller : Ber. d. chem. Ges., 4. 980. 20 grams benzaldehyde. 13 grams potassium cyanide. 15.3 cc. hydrochloric acid (sp. gr. 1.19). Put into a small flask 13 grams (i mol.) oipure potas- sium cyanide, and 20 grams (i mol.) of freshly distilled benzaldehyde. Place the flask in ice-water, and drop in slowly from a burette 7 grams (i mol.) of hydrochloric acid. This will be 14.3 cc. of an acid of sp. gr. 1.20, or 15.3 cc. of an acid of sp. gr. 1.19. During the addition of the acid shake frequently, and allow the mixture to stand for one hour after all has been added. Then pour into 150 cc. of cold water. Separate the cyanhydrin from the solution, and wash twice with water (see 5, p. 25). Transfer the nitrile to a porcelain dish, add 50 cc. of concentrated hydrochloric acid, and evaporate on a sand-bath till crystals begin to separate on the upper surface of the liquid. Dissolve the residue in about 100 cc. of warm water, filter from any oil which remains, and extract the mandelic acid from the filtrate with ether. In extracting with ether, especially when, as in this case, the substance to be extracted is easily soluble in water, the solution should be as concentrated as possi- ble. It is also an advantage, in many cases, to add salt or ammonium sulphate to the solution which is to be extracted. This lessens the solubility of the ether in the solution and also of the water in the ether. In ex- ACIDS. 39 tracting, put the solution to be extracted into a separa- tory funnel, which should be chosen of such size as to be nearly filled. Add, according to the ease with which the substance is extracted from the solution and accord- ing to the volume of the latter, 10-50 cc. of ether. When a substance is easily extracted, use but little ether ; if extracted with difficulty, a larger amount; and the extraction must, in such a case, be many times re- peated. These rules follow from the law for the divi- sion of a substance between two immiscible solvents, which is that the amounts retained in a unit volume of each have a fixed ratio, independently of the volume of each. The ratio is called the division-coefficient, and in the present case expresses the amount of substance con- tained in TOO cc. of the aqueous solution, divided by the amount contained in 100 cc. of the ethereal solution. Expressed mathematically, let x = amount of substance present. x l = amount of substance retained by the water. x x l = amount of substance retained by the ether. k = division-coefficient. / = amount of water. m = amount of ether. - = concentration of the ethereal solution. m -y\== concentration of the aqueous solution. Then by the definition '-5 1- or x l = kl Wl Wl 40 ORGANIC CHEMISTRY. kl or > *. = X ^^KT m and x x x n : ^-.. m + kl An examination of the last expression, which gives the amount of substance removed by a single extrac- tion, shows that if k is large, that is, if the substance is very soluble in water in proportion to its solubility in ether, the amount extracted increases rapidly with the amount of ether used, but that several extractions must be required. If k is small, however, an increase of m, or the amount of ether, has little effect on the value of the fraction and a few extractions with a small amount of ether will suffice. In extracting, after adding the ether, the stop-cock of the funnel should be inserted and held firmly in place while the contents are shaken vigorously. Only when there is danger of forming an emulsion which will sepa- rate into layers with difficulty, should the agitation of the liquids be more gentle. After shaking, the funnel should be inverted, and the stop-cock opened for a moment to relieve any pressure due to vapor of ether. The funnel is then set upright and allowed to stand till the two layers separate. In case separation does not take place satisfactorily it may be necessary to add more ether, or a few drops of alcohol. In extreme cases, fil- tration on a plate, or through a tube containing some cotton, may be necessary. Occasionally an emulsion can be caused to clear by connecting the funnel with the pump and exhausting till the ether boils for a short ACIDS. time. When separation has taken place, the aqueous solution is drawn off into a flask. It is usually an ad- vantage when the solution has been nearly removed, to give the funnel a slight rotary motion to collect the solution at the bottom, where it can be drawn off. The ether is then poured from the top of the funnel into a flask or distilling bulb, care being taken not to pour out any drops of the aqueous solution which may remain. The end of the extraction may be determined by taking a little of the ethereal solution in a dry test-tube, and evaporating the ether quickly by immersion in a boiling water-bath, and finally inverting the tube to allow the vapor of ether to fall out. In working with small quan- tities, extractions may sometimes be made with advantage in a test-tube and the ethereal solution drawn off with a small pipette, suction being ap- plied to the latter through a rubber tube long enough for the eye to be brought into a position to see the liquid . It is an advantage to draw the pipette out to a capillary below. The ethereal solution of the mandelic acid should be distilled and the residue dried on the water-bath in a watch-glass or porcelain dish. The acid, which crystal- lizes on cooling, may be recrystallized from benzene. Yield 10 to 15 grams. Fig. ii. 42 ORGANIC CHEMISTRY. Mandelic acid crystallizes from water in large rhombic crystals, and from benzene in leaflets, which melt at 1 18. 100 parts of water at 20 dissolve 15.97 parts of the acid. As with all substances prepared by synthesis from in- active bodies, it is inactive, but, as it contains an asym- metric carbon atom, it may be separated into two active forms. The separation may be effected by the crystalli- zation of the cinchonine salt, or by the growth of Penicil- lium Glaucum, or Saccharomyces ellipso'ideus, in a solu- tion of the ammonium salt. The former destroys the laevo form, the latter the dextro form. 9. Preparation of an Acid from an Amine through the Diazo Compound. Paratoluic acid, c H 4 375 ; i37 327 ; Gabriel, Zimmermann : Ber. d. chem. Ges., 13, 1680 ; Fittig, Kiesow : Ann. Chem. (Liebig), 156, 249 ; Sese- mann: Ber. d. chem. Ges., 6, 1086; 10, 758; Conrad, Hodgkin- son : Ann. Chem. (Liebig), 193, 300; Conrad: Ibid, 204, 136; Conrad, Bischoff : Ibid, 204, 180 ; Fittig, Christ : Ibid, 268, 122. For benzyl acetone, Ehrlich : Ibid, 187, n ; Jackson: Ber. d. chem. Ges., 14, 890; Harries, Eschenbach : Ibid, 29, 383. 2.3 grams sodium. 35 cc. absolute alcohol. 13 grams acetacetic ester. 12.6 grams benzyl chloride. 15 grams (about) benzyl acetacetic ester. 30 cc. alcohol. 10 grams sodium hydroxide. 30 cc. water. 40 cc. hydrochloric acid (sp. gr. i.u). Put 2.3 grams (i mol.) of sodium in a 100 cc. flask. Add 35 cc. of absolute alcohol, connect with an up- right condenser, and heat on a water-bath till the sodium is dissolved. Cool, add 13 grams (i mol.) of acetacetic ester, which, on shaking, will cause the sodium ethylate, which has separated, to dissolve. Add 12.6 grams (i mol.) of benzyl chloride, and heat on the water-bath with an upright condenser for two hours. The solution should now react neutral when a piece of dry reddened litmus paper is dipped in it and afterwards moistened. Cool, filter on a dry filter with the pump, and wash twice with a little alcohol. Distil the solution under ordinary pres- sure till the thermometer reaches 110, and then under ACIDS. 57 diminished pressure, using an oil- or air-bath. The Clai- sen distilling bulb may be used with advantage (see io,p. 47). The portion boiling at 160 170 under a pressure of 12 mm., or i8o-i9O under a pressure of 100 mm., will be nearly pure benzyl acetacetic ester, X COCH 3 C 6 H-CH,-CH( X C0 2 C,H 6 A small portion, which boils at 70 higher, consists of dibenzyl acetacetic ester; 12-15 grams of the monoben- zyl acetacetic ester should be obtained. Put the benzyl acetacetic ester in a 200 cc. flask, add 30 cc. of alcohol, and 10 grams of sodium hydroxide dis- solved in 30 cc. of water. Boil with an upright con- denser for an hour. Cool, dilute with about 50 cc. of water, and extract twice with 10-20 cc. of ether. Distil off the ether, dry the ketone which remains in vacuo over sulphuric acid, and distil ; or the ethereal solution may be dried with ignited potassium carbonate before the ether is distilled away. Evaporate the alkaline solution to about 20 cc. and add 40 cc. of hydrochloric acid (sp. gr. i.n). Thehy- drocinnamic acid usually separates as an oil, at first, but will solidify on standing in a cool place for some time. Filter, and recrystallize from hot water, reserving a very small crystal to cause the solidification of the acid, in case it separates again as an oil. The yield of the ketone and of the acid is about 3 grams each, but better yields may be obtained by work- ing with larger quantities. 58 ORGANIC CHEMISTRY. Benzyl acetone (i 3 -butylonphen) C 6 H B CH 2 CH 2 COCH 8 is a liquid which boils at 2^-2^6, and has a specific Q gravity of 0.989 at -^5. Hydrocinnamic acid crystallizes in long colorless nee- dles, which melt at 49. It boils at 280. It is easily soluble in boiling water, and in alcohol and ether. It is volatile in water vapor. It dissolves in 168 parts of water at 20. 14. Condensation of an Aldehyde with the Sodium Salt of an Acid. Perkin's Synthesis. Cinnamic acid, C 6 H B CH=CHCO 2 H. Literature. Perkin : Jsb. d. chem., 1877, 789 ; J. Chem. Soc., 31, 388 ; Tiemann, Herzfeld : Ber. d. chem. Ges., 10, 68 ; Edele- ano, Budistheano : Bull. Soc. China. [3], 3, 191; Michael : Am. Chem. J., 5, 205. Also see next preparation. 20 grams benzaldehyde. 30 grams acetic anhydride. 10 grams sodium acetate. In a 100 cc. flask place 10 grams of recently fused and powdered, dry, sodium acetate, 30 grams acetic anhydride, and 30 grams benzaldehyde, both recently distilled. Connect with an upright air condenser tube, i cm. in diameter and 60-80 cm. long. Heat in a small paraffin bath to the boiling-point of the mixture, about 1 80, for eight hours. Pour the contents of the flask while hot into a 500 cc. flask or distilling bulb. Rinse out with hot water and then distil with water vapor as long as benzaldehyde comes over. Add more water, if necessary, to dissolve the cinnamic acid, and a little ACIDS. 59 bone-black. Boil and filter hot on a plain or plaited filter, previously moistened. The cinnamic acid will crystallize from the filtrate on cooling. If it does not have the proper melting-point, recrystallize from hot water. Cinnamic acid crystallizes from water in colorless needles or leaflets, which melt at 133. It dissolves in 3500 parts of water at 17, much more easily in hot water. It combines with bromine to form a dibromide, C 6 H 5 CHBr.CHBrCO,H, which on treatment with alco- holic potash gives phenyl propiolic acid, C 6 H 5 C^^C CO 2 H. Ordinary cinnamic acid appears to be the cis- C 6 H 5 CH trans modification, || . Two other forms, H C CO 2 H one called isocinnamic acid, which melts at 57, and one called allocinnamic acid, which melts at 68, are known, but the causes of the isomerism are not fully understood. L,iebermann : Ber. d. chem. Ges., 23, 141, 2511; 24, 1102; 25, 950; 26, 1572; 27, 2038; Fock: Ibid, 23, 147, 2511 ; 24, 1105 ; 27, 2048 ; Ostwald : Ibid, 23, 516 ; 24, 1106 j Stohmann : Ztschr. phys. Chem., 10, 418. 15. Condensation of an Aldehyde with a Ketone and Oxidation of the Acetyl Group with Sodium Hypochlo- rite. Cinnamic acid, C 8 H B CH=CHCO 2 H. Literature. See last preparation, also Enjjler, Leist : Ber. d. chem. Ges., 6, 254, 257; Claisen, ClaparMe : Ibid, 14, 2461; Claisen, Ponder: Ann. Chem. (L,iebig), 223, 139; J. G. Schmidt: Ber. d. chem. Ges., 14, 1460 ; Meister, I/ucius and Briining, D. R. P., 21162, Ibid, 16, 449. 60 ORGANIC CHEMISTRY. 10 grams benzaldehyde. 25 cc. acetone. 10 cc. caustic soda (10 per cent.). 900 cc. water. In a one liter flask place 900 cc. of water, 10 grams of benzaldehyde, 25 cc. acetone and 10 cc. of caustic soda, free from carbonate. Mix thoroughly by shaking and allow to stand for four days, shaking occasionally. The aldehyde and acetone condense with the formation of benzalacetone, C 6 H 6 CH=CHCOCH 9 , and dibenzal- acetone, C 6 H 5 CH~CH CO CH=CH C 6 H B . Add 200 grams of salt (see 8, p. 38) and filter off and wash the dibenzal-acetone if it is solid, or extract twice with a small amount of ether, if it is liquid. Distil off the ether and fractionate the benzalacetone from a small distilling bulb (see Fig. 12,) under diminished pressure. The benzalacetone distils at I5i-i53 under 25 mm. pressure, at 26o-262 under 760 mm., and melts at 42. 2.5 grams benzalacetone. 12 grams chloride of lime. 15 grams sodium carbonate. 125 cc. water. To 12 grams of chloride of lime (containing 31 per cent, of available chlorine) add 50 cc. of water and 75 cc. of a solution of sodium carbonate (5 cc. = i gram Na,CO 8 ). Filter with the pump and wash once. To the filtrate add 2.5 grams of benzalacetone, warm to 8o- 90 and shake vigorously. Continue to warm and shake till the odor of chloroform is no longer apparent. The ACIDS. 6 1 benzalacetone should now have passed into solution. Cool, filter, precipitate the cinnamic acid with sul- phuric acid and recrystallize from hot water. The oxi- dation is exactly analogous to that by which chloroform is prepared commercially from acetone. For the prop- erties of cinnamic acid see above. 16. Preparation of Acids by Decomposition of Bibasic Acids. Formic acid, H.CO 2 H. (Methanoic acid.) Literature. Berthelot : Ann. Chim. Phys. [3], 46, 477; Ann. Chem. (Iviebig), 98, 139; Seekamp : Ibid, 122, 113; korin : Ann. Chim. Phys. [4], 29, 367 ; Romburgh : Compt. Rend., 93, 847; Roscoe : Ann. Chem. (Liebig), 125, 320; Maquenne : Bull. Soc. Chim. [2], 50, 662 ; I/iebig : Ann. Chem. (Iviebig), 171 69. 50 grams glycerine. 50 grams oxalic acid. Place in a 150 cc. distilling bulb 50 grams of glycerine, and 50 grams of crystallized oxalic acid. Insert a ther- mometer, immersed in the liquid. Connect with a con- denser, and heat with a low flame till the thermometer rises slowly to 105. Allow to cool to about 50, add 50 grams more of oxalic acid and distil again, always over a low flame and slowly to a temperature of 115. Repeat almost indefinitely, distilling to a temperature of 115- 125. The acid coming over in the later distillations will be stronger than that of the first. The residue may be used for the preparation of allyl alcohol (see 68.) Pure formic acid cannot be obtained from the dilute acid by distillation, the tendency being for a dilute acid to become more concentrated, or a concentrated acid weaker by distillation, till an acid boiling at 107 and of 62 ORGANIC CHEMISTRY. 77 per cent, finally passes over. Weaker acids may be concentrated to this strength by distillation. A nearly anhydrous acid can then be obtained by dissolving an- hydrous oxalic acid in this acid with the aid of heat, in such amount that on crystallizing with two molecules of water it will somewhat more than combine with all of the water present. After the oxalic acid has crystallized, the formic acid is poured off and distilled. An anhydrous acid may also be obtained by the de- composition of the lead salt with hydrogen sulphide. Formic acid melts at 8.3, boils at 101, and has a spe- cific gravity of 1.2256 at 15. The lead salt, which is easily prepared by dissolving lead carbonate in the hot dilute acid, is the most characteristic. It dissolves in 5^ parts of hot water, and in 63 parts of water at 16. The copper salt also crystallizes well. When heated with concentrated sulphuric acid, formic acid decomposes into water and carbon monoxide. On warming, it reduces solutions of silver salts with the sep- aration of metallic silver. On warming with mercuric chloride calomel separates. On heating the sodium salt with caustic soda, hydrogen is liberated. The specific gravity of the dilute acid is as follows : Per cent. CH 3 O a . Specific gravity at 15. 10 .025 30 .080 50 .124 70 .l6l loo .223 ACIDS. 63 17. Preparation of Acids from Natural Products. Stearic acid, C 17 H 33 CO 2 H. Literature. Pebal : Ann. Chem. (Liebig), 91, 138; Heintz : Ann. Chem. (I/iebig), 92, 295; Carnelly, Williams: Ber. d. chem. Ges., 12, 1360 ; J. Chem. Soc., 35.563; Krafft: Ber. d. chem. Ges., 15, 1724; 16, 1722; Saunders : Jsb. d. Chem., 1880, 831 ; David : Ztschr. anal. Chem., 18, 622 ; Krafft : Ber. d. chem. Ges., 22, 819 ; Hehner and Mitchell : J. Am. Chem. Soc., 19, 32. ioo cc. alcohol. 100 grams tallow. 35 grams potassium hydroxide. 35 cc. water. 90 cc. hydrochloric acid (sp. gr. i.i). Magnesium acetate. Melt ioo grams of tallow and pour it into a 500 cc. flask, add ioo cc. of alcohol and warm on a water-bath. Add in small portions 35 grams of caustic potash dis- solved in 35 cc. of water. After all has been added, dilute with 200 cc. of cold water. Add 90 cc. of hydro- chloric acid (4 cc. = i gram), and warm till the fatty acids melt and collect on top. Cool and separate the acids from the solution. Dissolve the acids in 500 cc. of warm alcohol, cool somewhat, and add enough of a solution of magnesium acetate 1 to precipitate 20 grams of stearic acid. Stir for five minutes, filter on a plate, and wash once with strong alcohol. To the filtrate add the same amount of the acetate, filter on a new filter, and repeat as often as a precipitate is obtained. From 1 Prepare the solution by dissolving 16.8 grams of magnesium carbonate or 8 grams of freshly ignited magnesium oxide in 85 cc. of acetic acid (30 per cent.), filtering, and washing to a volume of ioo cc. One cc. of the solution will precipitate 1.136 grams stearic acid. 64 ORGANIC CHKMISTRY. the last filtrate an impure oleic acid can be precipitated by water. Decompose each of the magnesium precipitates sepa- rately by warming and stirring with dilute hydrochloric acid till the fatty acid separates and melts to a clear liquid, and then allow each to cool and solidify. Crys- tallize each portion of the acids obtained from 15-20 times its weight of strong alcohol. Determine the melt- ing of each set of crystals obtained, unite portions hav- ing nearly the same melting-point and crystallize again, and repeat till a considerable quantity of pure stearic acid is obtained. It will usually be found best to crys- tallize rather slowly by spontaneous cooling, and not to allow the temperature to fall too low. The impure oleic acid referred to above may, if de- sired, be converted into the lead salt by digesting with litharge on the water-bath, and the lead oleate separated from the lead salts of other acids by solution in ether, or in alcohol (of sp. gr. 0.82) at 65. The oleic acid is set free by digesting the salt with hydrochloric acid, the acid converted into the barium salt, and the latter crys- tallized from alcohol. (Gottlieb: Ann. Chem. (Liebig), 57, 38.) Distillation under diminished pressure may also be used with advantage in purifying the fatty acids. The boiling-points and melting-points are as follows : BOILING-POINTS. Palmitic. Stearic. Oleic. At 15 mm. 215 232 232. 5 11 100 " 27i.5 291 286 "760 " 339-356 359-383 ACIDS. 65 MBI/TING-POINTS. Palmitic. Stearic. Oleic. 62 69. 2 or 7i-7i.5 14 Stearic acid crystallizes from alcohol in leaflets. It is soluble in 40 parts of cold absolute alcohol, in its own weight of alcohol at 50. Palmitic acid dissolves in 10 parts of cold alcohol. loo cc. of alcohol of sp. gr. 0.8183 will dissolve at o about 0.15 gram of stearic acid and about 1.2 gram of palmitic acid. (Hehner and Mitchell.) 18. Uric Acid. NH CO N = COH /I II CO C NH. or COHC NH \ II )co, ii ii \ COH NH C NH / N C N s u Literature. Liebig and Wohler: Ann. Chem. (Liebig), 26, 245 ; Wohler : 70, 229 ; 88, 100 ; Arppe : Ibid, 87, 237 ; Goes- mann : Ann. Chem. (I/iebig), 99, 374; Gibbs : Ztschr. Chem., 1869, 729 ; Am. J. Sci., 48, 215 (1869) ; Ann. Chem. (I^iebig), Supl., Bd. 7, 324 ; Horbaczewski : Ber. d. chem. Ges., 15, 2678 ; Behrend u. Roosen : Ber. d. chem. Ges., 21, 999 ; Ann. Chem. (L,iebig), 251, 235 ; Formanek : Ber. d. chem. Ges., 24, 3419 ; Ann. Supl., Bd. 2, 313 ; Fresenius : Ztschr. anal. Chem., 2, 456 ; Salkowski : Ibid, 16, 373 ; B. Fischer: Ber. d. chem. Ges., 17, 1785 ; 30, 549. i liter urine. 25 cc. concentrated hydrochloric acid. Add to one liter of urine 25 cc. of concentrated hydro- chloric acid and allow to stand in a cool place for two days. Decant the liquid from the crystals of uric acid and wash them by decantation. Transfer to a test-tube, 66 ORGANIC CHEMISTRY. dissolve in the smallest possible amount of 5 per cent, sodium hydroxide, add a drop of a solution of potassium pyrochromate and boil , then add a little bone-black , shake , and filter. Precipitate the uric acid with hydrochloric acid, allow to separate completely, filter, and wash. In working with larger amounts of uric acid the amount of the pyrochromate should be five per cent, of that of the uric acid, and after the second precipitation the uric acid, which is slightly yellow, should be warmed several times with strong hydrochloric acid, till it is perfectly white. (Gibbs: Loc. tit.) The yield from one liter of urine will usually be one- half a gram or less. Uric acid forms a white crystalline powder, which is almost insoluble in water, alcohol, and ether. It dis- solves in alkalies with the formation of salts in which two atoms of hydrogen are replaced by the metal. Car- bon dioxide precipitates from such solutions difficultly soluble acid salts, a property used in the preparation of the acid from guano. It is precipitated from its solu- tions by an ammoniacal solution of silver nitrate. If a little uric acid is moistened with nitric acid, and the solution evaporated on the water-bath, the residue dis- solves in ammonia to an onion-red solution, which be- comes violet on adding sodium hydroxide ("murexid reaction"). Nitric acid oxidizes uric acid to alloxan, X NH CO. C0( )C(OH) 8 + 3 H a O, X NH CO X ACIDS. 67 and the latter is decomposed by alkalies into urea and mesoxalic acid, X CO 2 H The structural formulae given above are based, in part, on these reactions. i9. Preparation of Levulinic Acid by the Action of a Dilute Acid on a Carbohydrate, CH 3 COCH,CH 8 C0 2 H. Literature Noeldecke : Ann. Chem. (Liebig), 149, 224, 228; Bente : Ber. d. chem. Ges., 8, 416; Tollens and Kehrer: Ann. Chem. (Liebig), 175, 181 ; 206, 207 ; Conrad : Ber.d. chem. Ges., ii, 2178; Fittig and Wolff: Ann. Chem. (Liebig), 208,105; Kent and Tollens : Ibid, 227, 229 ; Conrad and Gutzeit : Ber. d. chem. Ges., 18,442; 19, 2572; Neugebauer : Ann. Chem. (Lie- big), 227, 99 ; Rischbeth : Ber. d. chem. Ges., 20, 1773 ; Weh- mer and Tollens : Ann. Chem. (Liebig), 243, 314; Seissl: Ibid, 2 49> 275 ; Fittig ; Ber. d. chem. Ges., 29, 2583. ioo grams sugar. 400 cc. water. ioo cc. concentrated hydrochloric acid. Put in a 750 cc. flask ioo grams of cane sugar, 400 cc. of water, and ioo cc. of concentrated hydrochloric acid. Close the flask with a tube containing water as in the preparation of camphoric acid (see 3 p. 21). Heat on a water-bath for 20 hours. Filter on a plate, boil the resi- due of humus with ioo cc. of water and filter. To the combined filtrates add a solution of 35 grams of sodium hydroxide, and evaporate to about ioo cc. Filter again, ii necessary, and extract four or five times with 5075 cc. of ether, distilling the ethereal extract and using the 68 ORGANIC CHEMISTRY. same ether each time. For such cases it is convenient to put a separatory funnel through the stopper of the distilling bulb so that the ether may be introduced con- tinuously and without removing the bulb from the water-bath. A funnel should be placed in the mouth of the separatory funnel to facilitate the pouring of the ether, and care must always be taken to avoid ignition of the latter. After distilling off the ether, transfer the residue to a smaller distilling bulb, and distil under diminished pres- sure, raising the temperature of the oil- or air-bath slowly. Collect the portion boiling at i4O-i6o under 15 mm., or at i6o-i8o under 80-100 mm. Put this portion in a wide-mouthed, tightly-stoppered bottle and allow it to stand at o for some time, till it has solidified as far as possible. Pour off the liquid part, warm the residue gently till it melts, and allow it to crystallize slowly at ordinary temperatures. After draining off the liquid part the solid acid will be nearly pure. Yield 10- 15 grams. The reactions which take place are, first, the inver- sion of the cane sugar to levulose and glucose, and then the decomposition of these into levulinic and formic acids and water. CH 2 OH CHOH CHOH = CH 3 COCH 2 CH 2 C0 2 H + HCO 2 H + H 2 O. CHOH CHO ACIDS. 69 Levulinic acid melts at 33, and boils with slight de- composition at 245-246 under 760 mm. pressure, or at 1 48- 1 49 under 15 mm. If heated for some time at its boiling-point, it is converted into a mixture of a- and yff-angelica lactones, CH 3 C = CH CH a CO and CH 3 = C CH 2 CH a CO. O ' O It gives with phenylhydrazine a crystalline hydrazone, and is reduced to ^-hydroxyvaleric acid by sodium amalgam. On acidifying a solution of the sodium salt of this acid, valerolactone separates. II. Derivatives of Acids* The derivatives of organic acids are of two classes : those derivatives in which the carboxyl (CO 3 H) group is affected, and those in which the rest of the acid is changed. To the former class belong salts, chlorides, anhydrides, amides, and esters ; to the latter, halogen derivatives, nitro derivatives, amino-acids, hydroxy- acids, and, indeed, nearly or quite all classes of deriva- tives which may be formed from hydrocarbons. The chlorides of acids are prepared by treatment of the acid, or one of its salts, with phosphorus trichloride, phosphorus pentachloride or phosphorus oxy chloride. The trichloride is usually used for the lower members of the fatty acid series, and for cases where the boiling- point of the chloride is near that of phosphorus oxy- chloride. O O 3 RC OH + 2PC1 3 = 3 R C Cl + 3 HC1 + P 2 O 3 . For other cases, and especially when acids react with difficulty, phosphorus pentachloride is used. O O R C OH + PC1 6 = R C Cl + POC1 3 + HC1. Phosphorus oxy chloride is rarely used except with the salts of acids. DERIVATIVES OF ACIDS. 71 o o /f ^b 2 R C ONa+ POC1 3 = 2RC Cl + NaPO s + NaCl. The anhydrides of monobasic acids are usually pre- pared by the action of the chloride of the acid on its sodium salt. 00 S % R COC1 + RCO.ONa = R C O C R + NaCl. In some cases an excess of the alkaline salt is treated with phosphorus oxy chloride. 4 R CO.ONa+ POC1 3 = NaPO 8 + 3NaCl + 2R CO O CO R. Bibasic acids in which the two carboxyl groups are separated by two carbon atoms, either in the aliphatic or aromatic series (succinic and phthalic acids and their derivatives), readily form inner anhydrides, in most cases by the action of heat alone and at temperatures below 210. (Auwers: Ann. Chem. (L,iebig), 285, 223.) The formation of such anhydrides can be effected at lower temperatures, and in most cases quantitatively by the use of acetyl chloride, acetic anhydride, or phos- phorus oxychloride. 2R< C0 2 H + POC1 = 2R< CO >0 + 3HC1 + HPO 3 . Glutaric acid and its derivatives with open chains and, apparently, the "cis" forms of cyclic derivatives, also form anhydrides by the same treatment, but isophthalic acid gives no inner anhydride. 72 ORGANIC CHEMISTRY. Amides may be prepared in many cases by heating ammonium salts of acids. O O # s RC ONH 4 = R C NH 2 + H 2 O. Another method, which is applicable in almost all cases where the resulting amide is difficultly soluble in water, consists in treating the acid with phosphorus pentachloride to convert it into its chloride, and then adding the mixture of the chloride with phosphorus oxy- chloride carefully to cold concentrated aqueous ammo- nia, or ammonia gas may be passed into the mixture, diluted with benzene, ether, or chloroform. O O s s RC Cl + 2NH 3 = R C NH a + NH 4 C1. Esters, on treatment with ammonia, are converted into amides : O O S S R C OR' + NH 3 = R C NH 3 + R' OH. This method is seldom used, except in cases where other methods fail. (See Kinhorn and Bull: Ann. Chem. (Liebig), 295, 207.) The preparation of amides from nitriles or cyanides has been referred to on p. 4. Acids which form inner anhydrides form also imides in which the NH group takes the place of the oxygen atom which completes the ring in the case of the anhy- dride. These imides may be prepared by heating the ammonium salt of the acid : DERIVATIVES OF ACIDS. 73 = R NH + NH + H >- In some cases the ammonium salt of the half amide of the acid gives better results. The conversion of an anhydride into an imide by the action of ammonia prob- ably depends on the intermediate formation of such a salt: R + 2NH 3 =R NH + NH 3 +H 9 0. Closely related to the amides are anilides and similar compounds, which may be considered either as amides having a hydrogen atom of the NH 2 group replaced by a hydrocarbon residue, or as an amine having a hydro- gen atom of the amine group replaced by an acid radi- cal. Anilides and similar compounds may frequently be prepared by simply heating the acid with the amine, water being eliminated more easily than in the case of the ammonium salts. RCOOH + R'NH, = R CO NHR' + H 2 O. A more general method consists in treating the amine with the chloride or anhydride of the acid, either directly, or in the presence of an aqueous solution of sodium hy- droxide. ( " Schotten-Baumann reaction,'' see 26, p. 86.) Esters of strong acids may be prepared by bringing together the acid and alcohol. The action is aided by heat. The reaction is, however, a reversible one and proceeds only till an equilibrium is established between the amounts of ester, water, alcohol, and acid present. 74 ORGANIC CHEMISTRY. For equivalent weights of acid and alcohol, the per cent, of ester formed, when equilibrium is reached, is characteristic of the acid and alcohol in question, and varies greatly in different cases. Primary alcohols form esters more quickly and in larger amount than second- ary, and secondary than tertiary. In a similar manner acids with a primary carboxyl (R CH,CO 2 H) form es- ters more quickly than those with secondary carboxyl, and the latter more quickly than those with a tertiary carboxyl. These facts may be used to determine the structure of the alcohols and acids (Menschutkin, see third edition of Beilstein I, 218 and 389). The amount of an acid which will be converted into an ester is increased by the use of a larger amount of the alcohol, in accordance with the law of mass action, which applies to all reversible processes, that the in- crease of the amount of one of the reacting bodies in- creases the amount of the product or products (in this case ester and water) which result from its action on other substances present. It follows that an excess of the alcohol should be used when the acid is rare or expen- sive, and an excess of the acid when the alcohol is valuable. In most cases esterification is very much hastened by the addition of hydrochloric or sulphuric acid to a mix- ture of an organic acid and alcohol. It was formerly sup- posed to be necessary to saturate the mixture with dry hydrochloric acid gas, but Bmil Fischer has recently shown (Ber. d. chem. Ges., 28, 3252), that a compar- atively small amount of hydrochloric or sulphuric acid may frequently be used with better advantage. DERIVATIVES OP ACIDS. 75 Ksters may, in most cases, be readily prepared from the chlorides of acids by treatment with an alcohol. (SeeBaeyer: Ann. Chem. (L,iebig), 245, 140.) O O / / R C Cl + R' O H = RC OR' + HCl. They may also be prepared by treating a silver salt of an acid with an alkyl iodide, O O / / R C OAg + R'l = R C OR' + Agl. Halogen derivatives of acids are prepared by treating the acid, or, in many cases, either the chloride or bro- mide of the acid, with the free halogen. Unless the temperature is unduly raised so as to cause secondary reactions, aliphatic acids give by this treatment only a derivatives. (Erlenmeyer : Ber. d. chem. Ges., 14, 1318 ; Hell : Ibid, 14, 891 ; Auwers : Ibid, 24, 2209, 2233 ; Michael : J. prakt. Chem. [2], 36, 92 ; Volhard : Ann. Chem. (L,iebig), 242, 161.) 3 C n H 2n+I CO,H + P + i iBr = 3 C n H 2n BrCOBr + HP0 3 + 5HBr. ft derivatives may usually be obtained by treating aft unsaturated acids with the halogen acids. Bisubsti- tution products are obtained by the addition of the free halogen to unsaturated acids. The direct treatment of aromatic acids with halogens gives chiefly meta compounds. 76 ORGANIC CHEMISTRY. Hydroxy acids (frequently called, in accordance with historic nomenclature, oxy acids) , are prepared, in the aliphatic series, by treating halogen derivatives with sil- ver oxide or with alkalies, or by treating amino acids with nitrous acid. The latter method is also useful in the aromatic series. Other aromatic hydroxy acids are obtained either by Kolbe's (see 36, p. 101) or Reimer-Tie- mann's reactions (Ber. d. chem. Ges., 9, 423, 824; 10, 63, 213) , or by fusion of sulphonic or halogen derivatives with caustic potash : R + KOH = R + KNaSO - Cyclic acids derived from the aromatic acids have been obtained by the reduction of the latter with sodium amalgam, or with amyl alcohol and sodium. The same acids have, in several cases, been prepared from aliphatic compounds by methods of condensation. Hydrogen may be added to many unsaturated acids by reduction with sodium amalgam. 20. Preparation of an Acid Chloride. Acetyl chlo- ride, CH 3 .COC1. (Ethanoyl chloride.) Literature. Be"champ : Jsb. d. Chem., /#55, 504 ; 1856, 427 ; J. prakt. Chem., 65, '495; Thorpe: J. Chem. Soc., 1880, 37, 186; Bothamley, Thompson : Chem. News, 1890, 62, 191 ; Gerhardt : Ann. Chem. (Liebig), 87, 63. i oo grams acetic acid (glacial). 80 grams phosphorus trichloride. Arrange a 300 cc. distilling bulb, condenser and re- ceiver as indicated in Fig. 16. DERIVATIVES OF ACIDS. 77 All of the apparatus must be absolutely dry, and the side tube of the receiver should be connected with a tube which will deliver the hydrochloric acid evolved immediately over the surface of some water in a bottle. Place in the distilling bulb 100 grams (96 cc.) of glacial acetic acid, and add through the dropping funnel 80 grams of phosphorus trichloride. Warm for a short Fig. 16. time, gently, till the evolution of hydrochloric acid nearly ceases and the liquid separates in two layers. Then distil from a water-bath as long as anything comes over. The distillate usually contains some phosphorus trichloride. If a product entirely free from phosphorus is required, add two or three grams of powdered, dry, sodium acetate, allow to stand over night, and distil again from the water-bath, collecting the portion boiling at 50-56. Yield 80 to 90 grams. Acetyl chloride is a colorless liquid with a very disa- 78 ORGANIC CHEMISTRY. greeable odor. It boils at 50.9, and has a specific gravity of 1.1051 at 20. It decomposes rapidly with water or moist air and must be kept in tightly closed, glass-stoppered bottles. Acetyl chloride reacts readily with almost all bodies containing either an alcoholic hydroxyl, or an amine group. In both cases a hydrogen atom of the group is replaced by the acetyl group, C 2 H 3 O. The resulting compounds are, in many cases, crystalline and difficultly soluble in water, and hence well adapted for the charac- terization of bodies of these two classes. 21. Preparation of an Anhydride of an Acid. Acetic O O / \ anhydride, CH 3 C O C CH 3 . (Kthanoic anhydride.) Literature. Gerhardt : Ann. Chem. (Liebig), (1852}, 82, 131; 87, 149. 60 grams dry sodium acetate. 50 grams acetyl chloride. Place in a dry, 200 cc. flask, 60 grams of freshly fused dry, powdered sodium acetate, and connect with an up- right condenser. Add, in small portions, through the condenser, 50 grams of acetyl chloride, shaking vigorously after each addition. Warm on a water-bath as long as any acetyl chloride condenses and runs back. Then connect the flask with the condenser in the usual manner by means of rubber stoppers and a bent tube, and distil slowly with a free flame, holding the burner in the hand. Collect the portions boiling at 130- 142. Add to the distillate DERIVATIVES OF ACIDS. 79 two or three grams of dry sodium acetate and distil again. Yield 40 to 50 grams. Acetic anhydride is a colorless liquid with an un- pleasant odor. It boils at 138, and has a specific gravity of 1.08 at 15. With most bodies containing alcoholic or amine groups acetic anhydride reacts, giving the same prod- ucts as acetyl chloride. The reaction is usually less violent, and, of course, no hydrochloric acid is formed. Since acetic anhydride does not react very quickly with cold water, it may be used for the Schotten-Baumann reaction (26 and 30, pp. 86,91), while acetyl chloride cannot. 22. Preparation of the Anhydride of a Bibasic Acid. Succinic anhydride, CH.-C ^O. CH '~ on the addition of nitric acid. The nitrate is very difficultly soluble in nitric acid, and is converted into nitrourea, cold concentrated sulphuric acid. (See 77.) Urea forms double compounds with many salts and metal- lic oxides, and, also, compounds in which its hydrogen is replaced by metals. It is decomposed by alkaline hypo- bromites with liberation of nitrogen, a property used for its quantitative determination. Concentrated solutions of alkalies decompose it on boiling, with the formation of a carbonate and ammonia. Acids decompose it more rapidly. 25. Preparation of an Amide by Means of Phos- phorus Pentachloride and Ammonia. Phenyl sulphon- amide, C 6 H 6 SO 3 NH a . Literature. Mitscherlich : Ann. der Phys. (Pogg.) 31, 283, 631 ; Stenhouse : Ann. Chem. (Liebig), 140, 284; Gattermann : Ber. d. chem. Ges., 24, 2121 ; Michael, Adair : Ber. d. chem. Ges., I0 > 585 ; Gerhardt, Chancel : J. i8$2> 434 ; v. Meyer, Ador : Ann. Chem. (Liebig), 159, n ; Hybbeneth : Ibid, 221, 206. loo cc. fuming sulphuric acid (sp. gr. 1.87). 50 cc. benzene. 350 cc. water. 50 grams acid sodium carbonate. 100 grams salt. 20 grams crude sodium benzene sulphonate. 20 grams phosphorus pentachloride. 70 cc. ammonia (sp. gr. 0.90). 84 ORGANIC CHEMISTRY. To 100 cc. of fuming sulphuric acid, containing 5 to 8 percent, of the anhydride (sp. gr. 1.87 at 15) , in a 300 cc. flask, add, in small portions, 50 cc. of benzene, shaking vigorously after each addition and keeping the tempera- ture below 50 by occasional cooling. When the ben- zene has all dissolved, pour slowly into 350 cc. of water, cool, and filter from any diphenyl sulphone, (C 6 H B ) 2 SO 2 , which separates. Partly neutralize the acid by adding, carefully, 50 grams of acid sodium carbonate (baking soda), then add 100 grams of common salt, warm till it dissolves, filter and cool, with stirring. As soon as the sodium benzene sulphonate has separated completely, filter on a plate and suck dry. Moisten with a saturated solution of salt and suck dry again. Dry the salt on a plate of porous porcelain. Yield 40 to 50 grams of the salt. The salt can be crystallized from alcohol if de- sired, but is already pure enough for most purposes. Place in a 100 cc. flask 20 grams of phosphorus penta- chloride (weigh in the hood and avoid exposure to the air as far as possible), add 20 grams of crude sodium benzene sulphonate, dried at 120, close the flask with a perforated rubber stopper bearing a tube which will deliver the hydrochloric acid evolved just above the sur- face of water in a bottle or flask. Warm on the water- bath as long as hydrochloric acid is evolved. Cool. Pour the contents of the flask, in small portions, into 70 cc. of ammonia (0.90 sp. gr.) contained in a 200 cc. flask, cooling thoroughly after each addition. Filter, wash with cold water, and crystallize from hot water or from dilute alcohol. Yield 12 to 15 grams. DERIVATIVES OF ACIDS. 85 If benzene sulphonchloride is desired, the liquid prod- uct obtained by the action of the pentachloride on sodium benzene sulphonate may be poured in small portions into 200 cc. of cold water, and shaken with the latter for some time to decompose the phosphorus oxy chloride, the sulphonchloride taken up with ether, and after dry- ing with -calcium chloride and distilling off the ether, distilled under diminished pressure. Benzene sulphonchloride melts at 14.5 and boils with decomposition at 246. Under 10 mm. pressure it boils at 120. It has a specific gravity of 1.378 at 23. It may be used to distinguish the three classes of amines (Hinsberg: Ber. d. chem. Ges., 23, 2965). With primary amines it gives alkyl-sulphonamides, C B H 5 SO 2 NHR, which are soluble in alkalies, with sec- ondary amines it gives dialkyl-sulphonamides C 6 H 6 SO, NRR', which are insoluble in alkalies, and with tertiary amines it does not react. The compounds with primary and secondary amines may usually be prepared by the Schotten-Baumann reaction. Benzene sulphonamide crystallizes in needles from water, or in leaflets from alcohol. Both melt at 147- 148. (Hybbeneth gives 156.) It is easily soluble in alcohol and ether, difficultly soluble in cold water. The hydrogen of the amide group can be replaced by metals, hence the sulphonamides are soluble in alkalies, and some of them are quite soluble in a solution of sodium carbonate. 26. Preparation of the Benzoyl Derivative of a 86 ORGANIC CHEMISTRY. Phenol Schotten-Baumann Reaction. Phenyl benzo- O ate, C e H 5 C-0 C 6 H 6 . Literature. Baumann : Ber. d. chem. Ges., ig, 3218 ; Udrans- zky & Baumann : Ibid, ax, 2744 ; Hinsberg : Ibid, 23, 2962 ; Schot- ten : Ibid, 17, 2545. Dissolve about one-half gram of phenol in 5 cc. of water, add three-fourths gram of benzoyl chloride and a little caustic soda, enough so that the solution remains alkaline after warming, and shaking, till the odor of ben- zoyl chloride has disappeared. On cooling and stand- ing the phenyl benzoate solidifies, and, after filtering off and washing, may be crystallized from a little alcohol. It melts at 69. This reaction, which is generally applicable to alco- hols, phenols, and to primary and secondary amines, and in which acetic anhydride, sulphonchlorides and other similar compounds may be used instead of benzoyl chloride, is especially useful in converting liquid or easily soluble bodies into solid, difficultly soluble deriv- atives for purposes of identification. 27. Preparation of an Acid Derivative of an Amine. Acetanilide, C 6 H 6 NH.C 2 H 9 O. Literature. Gerhardt : Ann. Chem. (L,iebig), 87, 164 ; Wil- liams : Ibid, 131, 288; Witt: Dissertation, (Zurich, 1875), 12; J. Chem. Soc., 17, 106, (1864). 25 grams aniline. 35 grams glacial acetic acid. Put in a 200 cc. flask 25 grams of aniline and 35 DERIVATIVES OF ACIDS. 87 grams of glacial acetic acid. Place in the mouth of the flask a stopper bearing a tube one cm. in diameter and 50 cm. long. Heat on a thin asbestos paper on a wire gauze, and adjust the flame so that the vapors of acetic acid condense about two- thirds of the way up the tube. As water is formed during the reaction, it will gradually escape from the to'p of the tube, and this hastens the re- action. If the apparatus cannot be conveniently placed in a hood the top of the tube should be bent over, and a flask placed under it to collect the dilute acid which es- capes. After boiling for 4 to 5 hours, pour carefully, with stirring, into 400 cc. of water, filter when cold, and recrystallize from hot water, dilute alcohol, or from ben- zene. Yield about 80 per cent, of the theory. Acetanilide (known in medicine as antifebrin) melts at 1 1 6, and boils at 304. It dissolves in 189 parts of water at 6. It is easily soluble in hot water, alcohol, ether, and benzene. It may be saponified either by boil- ing with caustic potash or concentrated hydrochloric acid. 28. Preparation of an Ester. Ethyl acetic ester, O / (Acetic ether) CH 3 C OC a H B . (Ethyl Ester of Ethanoic Acid.) Literature. Geuther : Jsb. d. chem., 1863, 323 : Frankland, Duppa : Ann. Chem. (Iviebig), 138,205; Markownikoff : Ber. d. chem. Ges., 6, 1177; Pabst : Bull. Soc. Chim., 33. 35. 25 cc. alcohol. 25 cc. concentrated sulphuric acid. 88 ORGANIC CHEMISTRY. 200 cc. alcohol. 200 cc. glacial acetic acid. Place in a 250 cc. distilling bulb 25 cc. of alcohol, and 25 cc. of concentrated sulphuric acid. Put in the mouth of the bulb a stopper bearing a separatory funnel, the stem of which reaches nearly to the bottom of the bulb, and a thermometer which dips in the mixture. Con- nect with a condenser and heat carefully to 130- 135. Run in slowly a mixture of 200 cc. of glacial acetic acid and 200 cc. of alcohol, regulating the flow and the flame so that the temperature remains at about 135. Shake the distillate in a flask with a sodium carbonate solution till it no longer reacts acid, separate the aqueous solu- tion by means of a separatory funnel, add a solution of 50 grams of calcium chloride in 50 grams of water, shake, and separate again, to remove alcohol which it contains. Dry the acetic ether by allowing it to stand over night with a little fused calcium chloride, and frac- tionate. The portion boiling at 72 78 is nearly pure. For use in the preparation of acetacetic ether it should be allowed to stand a day with one-fifth of its weight of granular calcium chloride and filtered. Yield 80 to 90 per cent, of the theory. Acetic ester boils at 77, and has a specific gravity of o 0.9239 at --, and of 0.8300 at -- . It dissolves in 4 4 17 parts of water at 17.5, 28 parts of the ester dissolve one part of water. It is easily saponified by boiling with alkalies, and is slowly saponified by merely stand- ing with water. DERIVATIVES OF ACIDS. 89 29. Preparation of an Ester of a Bi basic Acid. CH.CO.C.H. Ethyl succinic ester, | CH.COAH. Literature. Weger : Ann. Chem. (Liebig), 221, 89; Fehling: Ibid, 49, 186, 195; Perkin: J. Chem. Soc., 45> 5*5 (^84) ; Crum Brown, Walker : Ann. Chem. (Liebig), 261, 115. 100 grams succinic acid. 170 cc. alcohol. 5 cc. concentrated sulphuric acid. In a 300 cc. flask put 100 grams of succinnic acid, 170 cc. of alcohol, and 5 cc. of concentrated sulphuric acid. Heat for two-hours on a water-bath with an upright condenser or condensing tube. Cool, and pour into a large flask containing 25 grams of sodium bicarbonate and 150 of water. Shake thoroughly, and separate the ester. Wash it once with a little water, dry, as directed, formalonic ester (see 7, p. 36), and fractionate. Yield good. Succinic ethyl ester boils at 2i7-2i8, and has a speci- fic gravity of 1.0475 at 25.5. 30. Preparation of the Ester of a Hydroxy Acid and of an Acetyl Derivative. Di-acetyl tartaric ethyl ester, C0 2 C,H 6 CH OC 2 H 3 O CH OCH0 83 Literature. Landolt; Ann. Chem. (Liebig), 189, 324; An- schiitz : Ber. d. chem. Ges., 18, 1399; Wislecenus: Ann. Chem. 90 ORGANIC CHEMISTRY. (Liebig), 129, 184; Perkin : A Supl., 5, 285 ; J. Chem. Soc., 51, 369 (1887") ; K. Fischer: Ber. d. chem. Ges., 28, 3255. 25 grams tartaric acid. 120 cc. absolute alcohol. i gram hydrochloric acid gas. Put 25 grams of tartaric acid in a 200 cc. distilling bulb, add 120 cc. of absolute alcohol, and pass into the bulb about one gram of hydrochloric acid gas. The gas may be generated in a small flask from salt and concen- trated sulphuric acid diluted with one-fourth of its volume of water, or by dropping concentrated sulphuric acid into commercial hydrochloric acid, and the amount can be de- termined by placing the bulb in a beaker on one pan of a balance , which is sensitive to about one-tenth gram . Close the side tube of the bulb with a bit of rubber tubing and a glass rod, and place in the mouth of the bulb a stop- per and tube to act as an air condenser. Heat for 2 to 3 hours on a water-bath, inclining the bulb in such a manner that the vapors which condense in the side tube will run back into the bulb. Adjust a capillary tube and stopper, and a second bulb to collect the distillate, as on p. 46, and distil the excess of alcohol and the water formed under gradually diminishing pressure, and finally dry for fifteen minutes under as low a pressure as can be secured and with the bulb immersed in a boiling water- bath. Add 80 cc. of absolute alcohol, and i gram of hydrochloric acid, and heat as before with an air con- denser for two hours. By the removal of the water formed by the esterification, and a second treatment with fresh alcohol a much more complete conversion can be DERIVATIVES OF ACIDS. 91 secured. Distil the alcohol and water as before and then distil from an oil-bath or with the free flame under as low a pressure as can be secured and with a ther- mometer (see p. 46). The portion boiling at i6o-i8o under 30 mm. pressure will consist of nearly pure di- ethyl tartaric ester. Yield 23-26 grams. The ester boils at 280 under a pressure of 760 mm. 232 " " " 197 " 162 " " " 19 " 157 " " " ii " It has a specific gravity of 1.2059 at 20. 3 grams di- ethyl tartaric ester. 5 grams acetic anhydride. 30 cc. sodium hydroxide (10 per cent.). Place in a small flask 3 grams of di-ethyl tartaric ester, add five grams of acetic anhydride and then, in small portions, with constant shaking, 30 cc. of a 10 per cent, solution of sodium hydroxide. As soon as the odor of the acetic anhydride has disappeared, filter off the acetyl derivative if it solidifies, wash it with water and recrystallize it from alcohol, dissolving in a very lit- tle hot alcohol, and adding water till the solution begins to become turbid. If the acetyl compound fails to solidify at first it will usually do so on standing in a cool place for a day or two. If some of the crystallized compound is at hand the addition of a crystal will be of service. Di-acetyl tartaric ethyl ester melts at 67, and boils at Q2 ORGANIC CHEMISTRY. 29i-292 under 727 mm., or at 22g-2^o under 100 mm. Very considerable historical interest attaches to the substance, because by means of it the structure of tar- taric acid was first clearly established. 31. Preparation of an Ester by Means of Phosphorus Pentachloride and Alcohol. Benzoic ethyl ester, C 6 H 6 CO,C,H 6 . Literature. Baeyer : Ann. Chem. (Liebig), 245, 140; Liebig : Ibid, 65, 351 ; E. Fischer, Speier : Ber. d. chem. Ges., 28, 1150, 3255. 10 grams benzoic acid. 21 grams phosphorus pentachloride. 50 cc. alcohol. Put in a small flask 10 grams of benzoic acid, and 21 grams of phosphorus pentachloride. Connect with a tube which will deliver the hydrochloric acid evolved just above the surface of water in a bottle. Warm on a water-bath till all is liquid. Cool, and pour carefully into 50 cc. of alcohol. Cool thoroughly, add 100 cc. of water and enough ether to bring the benzoic ester to the surface. Separate, wash with a solution of sodium car- bonate to remove acid, dry the ethereal solution by al- lowing it to stand for several hours with dry potassium carbonate, pour off, or filter, and distil from a small dis- tilling bulb. Other methods of preparing benzoic ester are more suitable, and this method is only given as an illustration of a method which is quite generally applicable. The yield is almost quantitative if care is used. DERIVATIVES OF ACIDS. 93 Benzole ester boils at 211, and has a specific gravity of 1.0502 at 16. 32. Preparation of a Bromine Derivative of an Acid. Hell-Volhard - Zelinsky's Method. a- Brom-butyric Fig. 17. acid, CH 3 CH 2 CHBr.CO,H. Brom-(2)-butanoic acid. Literature. Borodin: Ann. Chem. (Liebig), 119, 121; Nau- mann: Ibid, 119, 115; Hell: Ber. d. chem. Ges., 14,891; ax, 1726; Volhard: Ann. Chem. (lyiebig), 242, 141; Ber. d. chem. Ges., 21, 1904; Zelinsky : Ibid, 20, 2026; Auwers and Bern- hardi: Ibid, 24, 2216; Hell and L,auber : Ibid, 7, 560. 17.6 grams butyric acid. 2.2 grams red phosphorus. 60 grams bromine (2occ.). 94 ORGANIC CHEMISTRY. Select a small Liebig condenser whose inner tube will pass just inside of the neck of a 50 cc. round-bottomed flask. Cut off the lip of the flask, put the end of the con- denser in its mouth and connect by means of a rubber tube, which slips over both, as is done with some forms of con- densers. (SeeFig. 17.) Put in the flask 2. 2 grams ( at.) of red phosphorus, and 17.6 grams (i mol.) of normal butyric acid. Add slowly from a dropping tube with a glass stop-cock, or from a bulb drawn out to a capillary below, through the top of the condenser, 60 grams (* at.) of bromine. The bromine is best measured from a dry burette or measuring tube, in a good hood or out of doors. The top of the condenser should be closed with a doubly perforated stopper, one hole carrying the dropping tube, and the other a tube leading out of doors or just over the surface of a solution of caustic soda in a bottle. Drop in the bromine slowly, and warm very gently on a water-bath till the vapors of bromine disap- pear, usually about an hour. Cool, and pour the con- tents of the flask, in small portions, upon 50 grams of ice in a flask. Shake vigorously, keeping the contents of the flask cold, till the bromide of the brombutyric acid is decomposed, and the odor of phosphorus oxy- bromide has disappeared. Separate the acid from the aqueous solution, wash it once with a small amount of water, and distil it under diminished pressure. The portion boiling at i35-i4o, under a pressure of 35 mm. will be nearly pure. In working with a small amount of acid the bromi- nation may be effected with advantage by putting a DERIVATIVES OF ACIDS. 95 weighed quantity of the acid in a sealed tube, convert- ing it into the chloride by the calculated amount of phosphorus pentachloride, putting in a bulb containing two atoms of bromine for one molecule of the acid, seal- ing the tube, breaking the bulb containing the bromine by shaking the tube, and heating, till vapors of bromine disappear, in a water-bath. On cooling and opening the tube the phosphorus oxychloride may be decom- posed by shaking with cold water and, in case the chlo- ride of the acid is not readily decomposed in this way, it may be taken up with ether, the solution dried with calcium chloride, the ether distilled, and the chloride decomposed by warming with glacial formic acid. See Baeyer : Ann. Chem. (L,iebig), 245, 175 ; Aschan: Ibid, 271, 265. or-Brombutyric acid boils with some decomposition at 2i2-2i7. It boils without decomposition at 136-! 38 under a pressure of 35 mm. The specific gravity at 15 is 1.54. It dissolves in about 15 parts of water. When treated with alcoholic potash it is converted into cis-cro- H C C0 2 H tonic acid, || . The yield is, however, H C CH 3 poor, owing to the formation of hydroxy-butyric acid and other substances. 33. Preparation of a Nitro Derivative of an Aromatic Acid. Meta-nitro-benzoic acid, C fl H 4 <^ H ^. Literature. Mulder: Ann. Chem. (lyiebig), 34, 297; Gerland : Ibid, 91, 186; Griess: Ber. d. chem. Ges., 8, 526; 10, 1871; 96 ORGANIC CHEMISTRY. Widmann : Ann. Chem. (Liebig), 193, 202; C. I/iebermann ; Ber. d. chem. Ges., 10, 862 ; Ernst : Ztschr. chem., 1860, 477. 25 grams benzole acid. 50 grams potassium nitrate. 75 grams absolute sulphuric acid (monohydrate). Warm 75 grams of absolute sulphuric acid 1 to 70 in a beaker, and add, in small portions, a powdered mixture of 25 grams of benzoic acid and 50 grams of potassium nitrate, stirring vigorously and keeping the temperature at 8o-9O. When all has been added, and the nitro- benzoic acid has separated as an oily layer on top, pour the contents of the beaker into a porcelain dish, and allow the product to solidify. Separate the cake of nitro acids from the acid potassium sulphate. Put in the nitro acids (about 75 per cent, of meta, 22 per cent, of the ortho, and 2^ per cent, of the para acids are pres- ent in the mixture) in a beaker with 100 cc. of water, heat till the acids melt, and stir thoroughly. Cool, filter, and wash with cold water. Dissolve the acid, in 300- 400 cc. of hot water, and add a clear concentrated solu- tion of barium hydroxide (about 30 grams) to alkaline reaction. Cool, filter, and wash. The barium salts of the ortho and para acids pass into the filtrate, while a part of the ortho acid remained in solution on treatment with water before. The pure meta acid can be ob- 1 Absolute sulphuric acid, called technically the " monohydrate," can be purchased or may be prepared by cooling concentrated sulphuric acid to o, or below, until it crystallizes and pouring off the liquid portion, the crystals consisting of absolute sulphuric acid, if the acid is sufficiently strong. The crystallization may be started with crystals obtained by cooling a mixture of ordinary sulphuric acid with the fuming acid. DKRIVATIVES OF ACIDS. 97 tained by treating the barium salt with 200 cc. of hot water and some hydrochloric acid, filtering hot from the barium sulphate, which separates, and cooling the fil- trate. Meta-nitro-benzoic acid melts at i4i-i42. It dis- solves in 10 parts of hot water, and in 425 parts of water at 16.5. It is very easily soluble in alcohol and ether. The barium salt is soluble in 19 parts of boiling water, and in 265 parts of cold water. The ortho and para acids may also be separated from the mixture obtained by the nitration of benzoic acid, but are more readily obtained by the oxidation of the nitro-toluenes. (See 5 p. 24). 34. Preparation of an Ammo Acid from a Halogen De- rivative of an Acid. Glycocoll, CH t p. 25), add once more an equal volume of water and, with frequent shaking, caustic soda till the methyl iodide is colorless. Separate again, transferring the iodide to a small distilling bulb, add some fused, powdered calcium chloride and distil again from the water-bath after about an hour, using a thermometer. Methyl iodide boils at 42.8, and has a specific gravity of 2.2852 at 15, or 2.2529 at 25. On heating with fif- teen parts of water at 100 it is converted into methyl alcohol and hydriodic acid. Because of its low boiling-point and high molecular weight it escapes rapidly unless kept in small bottles tightly stoppered with cork stoppers, or, better, in sealed tubes. For the preparation of large quantities of ethyl or methyl iodide the method of Walker (loc. cit.) is to be recommended. 38. Preparation of a Bromine Derivative of a Hy- drocarbon from an Alcohol with Sulphuric Acid and Potassium Bromide. Ethyl bromide, C a H 6 Br. Literature Serullas : Ann. Chim. Phys. [2], 34, 99, (1827); Loewig : Ann. Chem. (Liebig), 3, 288 ; Perkin : J. prakt. Chem., 31, 497 ; R. Schiff : Ber. d. chem. Ges., 19, 563 ; Riedel : Ibid, 24, R. 105. 90 grams potassium bromide. 100 cc. alcohol. 100 cc. concentrated sulphuric acid. 70 cc. water. Put zoo cc. of concentrated sulphuric acid in a flask, add slowly with constant shaking, but within two or three minutes, 100 cc. of alcohol. Cool thoroughly and IIO ORGANIC CHEMISTRY. pour the mixture into a 400 cc. distilling bulb or flask containing 70 grams of potassium bromide, and 70 cc. of water. Distil quite rapidly, heating on a wire gauze covered with a thin sheet of asbestos and using a good condenser, as long as ethyl bromide comes over. A little water should be placed in the receiver to absorb hydrobromic acid which is given off. Separate the ethyl bromide from the aqueous layer and add to it, with careful cooling, concentrated sulphuric acid till the acid separates below. This will remove any ether which has been formed. Separate again, wash twice with a small amount of water, put the bromide in a distilling bulb with some fused, powered calcium chloride and distil with a thermometer after one or two hours. Yield 55 to 60 grams. The reactions involved in the preparation are as fol- lows : C a H 6 OH + H 2 S0 4 = C 3 H B HS0 4 + H 3 O. Ethyl sulphuric acid. C a H 5 HS0 4 + KBr= C a H 5 KSO 4 + HBr. Ethyl potassium sulphate. C 3 H 5 KSO 4 + HBr = C 2 H B Br + HKSO 4 . Ethyl bromide may also be prepared by the action of bromine on red phosphorus and alcohol, but the method here given is more satisfactory and gives a purer prod- uct, unless red phosphorus free from arsenic is available. Ethyl bromide boils at 38.4, and has a specific gravity of 1.476 at 15. It must be kept in tightly corked, not glass stoppered bottles. Ethyl bromide is sometimes used as an anaesthetic. HALOGEN COMPOUNDS. Ill For this use it must be entirely free from arsenic. Arsenic, if present, may be detected by burning the sub- stance in a small spirit lamp, and drawing the products of combustion through a solution of caustic soda. The solution may then be tested for arsenic by means of hy- drochloric acid and a concentrated solution of stannous chloride. 40. Preparation of a Bromine Derivative of an Aromatic Hydrocarbon. Para-dibrombenzene, OTT Br (i) C'-^Br (4)' Literature. Couper : Ann. Chim. Phys. [3], 52, 309, (1858); Riese ; Ann. Chem. (Liebig), 164, 162 ; Jannasch; Ber. d. chem. Ges., 10, 1355. 50 grams benzene (56.5 cc.). 210 grams bromine (67 cc.). i gram iron filings. Put 50 grams of benzene in a dry, 200 cc. flask. Add i gram of iron filings or turnings, and close the mouth with a stopper bearing a drop funnel which dips below the surface of the benzene, and an exit tube. Putin the drop funnel, best out of doors, 67 cc. of bromine. Place the flask in a water-bath filled with cold water, and con- nect the exit tube with a tube opening just above the surface of water in a large bottle. Allow the bromine to flow slowly into the benzene. Toward the end, aid the reaction by heating the water-bath slowly to the boiling-point. When the reaction is complete and no more vapors of bromine appear, distil from the flask or from a distilling 112 ORGANIC CHEMISTRY. bulb, collecting the portion boiling at 2oo-23o by itself. Crystallize from a small amount of alcohol. Yield 50 to 60 grams of />-dibrombenzene. Para-dibrombenzene crystallizes in white prisms or leaflets which melt at 89, and boil at 219. 41. Substitution of Chlorine in the Side Chain of an Aromatic Hydrocarbon. Benzyl chloride, C 6 H B CH 2 C1. Literature. Cannizzaro : Ann. Chem. (Liebig), 96, 246 ; Beil- stein, Geitner : Ibid, 139*332; Ivauth, Grimaux : Ibid, 143, 80; Schramm ; Ber. d. chem. Ges., 18,608; Haase : Ibid, 26, 1053. 100 grams toluene. loo grams manganese dioxide. 540 cc. commercial hydrochloric acid. Put in a 200 cc. flask 100 grams (115 cc.) of toluene and connect it with an upright condenser. Place in the upper end of the condenser a tight stopper bearing two glass tubes, one passing just through the stopper and the other reaching nearly to the bottom of the flask. Con- nect the first tube with a tube opening just above the surface of water in a bottle. Or arrange one tube pass- ing through the stopper side of the condenser, and con- nect the other with the top of the condenser, as in Fig. 19. Heat the toluene to boiling and pass in chlorine generated in a liter flask by the slow addition of 540 cc. of commercial hydrochloric acid to 100 grams of manga- nese dioxide, the mixture being warmed gently and the gas purified by passing it through a wash-bottle con- taining water, and then through one containing concen- trated sulphuric acid. The operation must be carried out in clear daylight, or, if possible, in the direct sunlight. HALOGEN COMPOUNDS. Fig. 19. When the evolution of chlorine has ceased, submit ther* product in the flask to fractional distillation. The por- tion boiling below 150 consists chiefly of unchanged toluene and may be used for a new preparation. After fractioning two or three times the portion boiling at i76-i8i will consist of nearly pure benzyl chloride. The yield varies according to the brightness of the sun- light in which the operation is conducted. In some cases the weight of benzyl chloride may equal that of the toluene used. Benzyl chloride is a colorless liquid with an unpleas- ant odor. Its vapor attacks the eyes very strongly. It 114 ORGANIC CHKMISTRY. boils at 178 and has a specific gravity of 1.113 at J 5- By long boiling with water it is converted into benzyl alcohol. Oxidizing agents oxidize it to benzoic acid.. The higher boiling portions contain some benzal chlo- ride, C 6 H 6 CHC1 2 , which boils at 203.5. 42. Preparation of a Bromine Derivative of a Hydro- carbon from an Aromatic Amine. Parabromtoluene, CH 3 (i). C H
NK = C H < NR + KCL C 6 H 4 <>NR+2H 2 + HC1 = C H <C=NOH + 4 H = |,>CHNH 1 + H 1 0. |,>C=NNHC.H.+ 4 H = |, > CHNH 8 + C.H.NH,. The most useful reducing agent for the oximes ap- pears to be absolute alcohol and sodium. The same method may also be applied to hydrazones. Or the latter may be reduced by zinc dust and acetic acid in alcoholic solutions. Nitriles may be reduced to amines by absolute alco- hol and sodium, and in some cases, also, by the use of zinc and hydrochloric or sulphuric acid. R C=N+ 4 H = R CH 2 NH 2 . When acid amides are treated with bromine and sodium hydroxide, or, in many cases, if treated with an alkaline solution of sodium hypobromite, they are con- verted into amines with loss of carbon dioxide. R CONH 2 + NaOBr + 2 NaOH = RNH a + NaBr + H a O + Na 2 CO 3 . The most plausible explanation of this reaction ap- pears to be that given by Stieglitz, based on the work of Nef (Am. Chem. J., 18, 751). R CONH 2 + NaOBr = R CO NHBr + NaOH. R C=O \ w + NaOH = R C = O + NaBr + H 2 O. N < I AMINES. 133 R C=O C=O I II ; N R N CO + H 2 = RNH 2 + CO a . An illustration of this reaction has been given in a previous chapter (see 35 p. 99). ' Aromatic amines may sometimes be prepared from phenols by heating with concentrated ammonia in sealed tubes, or by heating with ammonia and zinc or calcium chloride. ROH+ NH 3 = RNH 2 + H 3 O. Dimethyl and diethyl amine can be prepared with ad- vantage by decomposing />-nitrosodimethyl- or diethyl- aniline with caustic soda. 6)2 + NaOH = C H < NH(C,H 5 ) 2 . 49. The Preparation of an Amine by the Reduction of a Nitro Compound. Aniline, C 6 H B NH 2 . Literature. Unverdorbeu ; Pogg. Ann., 8, 397 ; Runge : Pogg. Ann., 31, 65 ; 32,331; Fritsche : Ann. Chem. (Liebig), 36, 84; 39, 76 ; Anderson : Ibid, 70, 32 ; Hoffmann : Ibid, 55, 200 ; 53, ii ; Wohler : Ibid, 102, 127; Merz, Weith: Ber. d. chem. Ges., 13, 1298; Merz, Miiller : Ibid, 19, 2916 ; Reverdin, Harpe : Ibid, 22, 1004. 25 grams nitrobenzene. 45 grams tin. 100 cc. commercial hydrochloric acid. 1 For a modification of Hoffmann's reaction see note, p. 147. 134 ORGANIC CHEMISTRY. Put into a 500 cc. flask 25 grams of nitrobenzene and 45 grams of tin. Add about 10 cc. of commercial hydro- chloric acid (sp. gr. 1. 16), and shake vigorously. If the solution becomes so hot as to boil, cool it somewhat by dipping the flask in cold water. When the reaction moderates add 10 cc. more of the acid, and continue in the same manner till 100 cc. have been added. Warm on the water-bath till the odor of nitrobenzene disap- pears. Cool, add, with further cooling, if necessary, a solution of 75 grams of caustic soda in 100 cc. of water, and distil off the separates aniline with water vapor, dis- tilling about 100 cc. after the distillate ceases to appear turbid. Add to the distillate 20 to 30 grams of salt and some ether, separate the ethereal solution, dry it by allowing it to stand for some time, best over night, with some powdered caustic potash, pour off into a distilling bulb, distil the ether from the water-bath, and then the aniline with a free flame. Yield 15 to 17 grams. Aniline is a colorless oil with a slightly aromatic odor. It melts at 8, boils at 183.7, atl d has a specific gravity of 1.036 at o, and 1.0276 at 11.6. Aniline forms salts which crystallize well, but these react acid toward test papers. Aniline dissolves in 31 parts of water at 12.5. The chloride is easily soluble in alcohol and in water, and melts at 192. It is less easily soluble in hy- drochloric acid, a characteristic which may be used with advantage in the crystallization and purification of many of the chlorides of organic bases. Aqueous solutions of aniline give a violet color on the addition of a few drops of a solution of calcium hypochlorite (chloride of lime). AMINES. 135 50. Preparation of a Nitro-Amino Compound by the Reduction of a Dinitro Compound. p-amino-o- /CH S (i). nitrotoluene, C 6 H 3 NO 2 (2). \NH, (4). Literature. See 48, p. 128 ; also Beilstein and Kuhlberg : Ann. Chem. (lyiebig), 155, 13. 15 grams toluene. 35 cc. nitric acid (1.42). 35 cc sulphuric acid. 75 cc. sulphuric acid. 15 grams dinitrotoluene. 50 cc. alcohol. 8 cc. ammonia (0.90). Hydrogen sulphide. Put 15 grams of toluene in a small flask and add in small portions, 70 cc. of a mixture of equal volumes of concentrated sulphuric and concentrated nitric acids, shaking vigorously and cooling somewhat. After the mixture has all been added and the reaction moderates, add 75 cc. of concentrated sulphuric acid, shake vigor- ously, heat to about 130 and keep the mixture at that temperature, shaking vigorously for about 15 minutes. Allow to cool, pour into water, filter, wash, and crystal- lize the dinitrotoluene from alcohol. 20 to 25 grams of pure dinitrotoluene, melting at 70.5, should be obtained. Put 15 grams of the dinitrotoluene in a flask, add 50 cc. of alcohol and 8 cc. of concentrated ammonia (0.90), pass in a rapid current of hydrogen sulphide nearly to saturation, connect the flask with a reversed condenser 136 ORGANIC CHEMISTRY. or condensing tube, and heat on a water-bath for half an hour. Cool, saturate again with hydrogen sulphide, and heat as before. Filter hot, cool the filtrate, add water, and filter off the precipitated nitrotoluidine after stand- ing for some time. Purify by dissolving in dilute hydrochloric acid, filtering, and precipitating again with ammonia. Yield about 10 grams. Orthonitroparatoluidine crystallizes from water in broad yellow monoclinic needles, which melt at 77.5. It is difficultly soluble in water and carbon bisulphide, easily soluble in alcohol and acids. 51. Preparation of a Diamino Derivative of Benzene. ^-Phenylendiamine, C 6 H 4 < 3 fa (/-Diamino- benzene) . Literature. Grethen : Ber. d. chem. Ges., 9, 775 ; Beilstein, Kurbatow : Ann. chem. (Liebig), 197, 83: Nolting, Collins: Ber. d. chem. Ges., 17, 262; Hobrecker : Ibid, 5, 920. 20 grams acetanilid. 75 cc. nitric acid (1.42). 30 cc. sulphuric acid (1.84). 20 grams nitro acetanilide. 30 grams tin. 80 cc, commercial hydrochloric acid. Hydrogen sulphide. Lime. Prepare ^-nitroacetanilide exactly as directed for nitro- acettoluide (see46,p. 124). Put in a flask 20 grams of nitro- acetanilide and 30 grams of tin. Add 10 cc. of concentra- AMINES. 137 ted commercial hydrochloric acid, and shake till the reac- tion begins to moderate; add more of the acid and shake as before, and continue till 80 cc. of acid have been added. Then heat on the water-bath till the reaction is com- plete. The nitro group is reduced and the acetyl group is also removed. Dilute with three or four volumes of water, pour off from any undissolved tin, precipitate the tin from the solution with hydrogen sulphide, and filter on a Witt plate or Hirsch funnel (see 3, p. 21). The hydrogen sulphide is best generated in a two- liter acid bottle from considerably more than the theoretical amount of iron sulphide, which is placed in the bottle with 1500 cc. of water. Somewhat more than the theoretical amount of concentrated com- mercial sulphuric acid is then added, in small portions, through the thistle tube. The gas should be passed through a washing tube or wash-bottle containing a lit- tle water. After the operation is over, the generator should be emptied at once, as the ferrous sulphate would crystallize on standing. If any unused ferrous sulphide is left in the bottle, and the latter is filled up at once with water to prevent its oxidation, it can be saved for use again. Evaporate the filtrate to a small volume, filter again, if necessary, through a hardened filter, and allow the chloride of the phenylene derivative to crystallize. To prepare the free amine, mix the chloride with an equal weight of quicklime, and distil from a small re- tort. The paraphenylenediamine may be recrystallized from benzene. Yield 10 to 12 grams. 13 ORGANIC CHEMISTRY. Paradiaminobenzene crystallizes from benzene in shin- ing leaflets, which melt at 140 and boil at 267. It is moderately soluble in hot water. Paranitroacetanilide melts at 207. 52. Preparation of an Amine by the Decomposition of an Alkyl Derivative of Aniline. Diethylamine, (C 9 HJ 3 NH. Literature. Hoffmann : Ann. Chem. (Liebig), 74, 128, 135 ; Elsbach : Ber. d. chem. Ges., 15, 690; Piutti : Ann. Chem. (Liebig), 227, 182; Pictet: Ber. d. chem. Ges., 20, 3422; Schloe- mann : Ibid, 26, 1020; Reynolds : J. Chem. Soc., 6x, 457 ; Kopp : Ber. d. chem. Ges., 8, 621 ; L,ippmann u. Fleissner : Ibid, 16, 1422 ; Hoffmann : Ann. Chem. (Liebig), 73, 91 ; Wallach : Ibid, 214, 275; Reinhardt and Staedel: Ber. d. chem. Ges., 16, 29 ; Baeyer and Caro : Ibid, 7, 963. 30 grams aniline. 45 grams ethyl bromide. 20 grams sodium hydroxide. 60 cc. water. 35 grams ethyl aniline. 45 grams ethyl bromide. 20 grams sodium hydroxide. 60 cc. water. 30 grams diethylaniline. 150 cc. water. 120 cc. concentrated hydrochloric acid (1.19). zoo grams ice. 1 6 grams sodium nitrite. 80 cc. water. 70 grams sodium hydroxide. 210 cc. water. AMINES. 139 Put in a small flask 30 grams of aniline and 45 grams of ethyl bromide, and heat with a reversed condenser for one or two hours, or until the mass solidifies. Cool, add 60 cc. of a solution of sodium hydroxide (3 cc. = i gram), with cooling, separate the ethyl aniline, add to it 45 grams of ethyl bromide, and heat with reversed con- denser as before, till the mass solidifies. Dissolve in water, boil to expel any ethyl bromide which remains, cool, add 60 cc. of caustic soda, and separate the diethyl aniline. Dry with powdered potassium hydroxide, and distil, collecting as much as possible of the portion boil- ing at 2i2-2i5. (Aniline boils at 183.7, ethyl ani- line at 206, and diethyl aniline at 213.5.) Dissolve 30 grams of the diethyl aniline in 120 cc. of concentrated hydrochloric acid and 150 cc. of water, cool, add loo grams of ice, and when the solution is near o add slowly, with stirring, 16 grams of sodium nitrite dissolved in 80 cc. of water. After an hour transfer the solution of nitrosodiethyl aniline, C 6 H 4 C 251 ; Hoffmann : Ber. d. chem. Ges., 15, 768 ; Tafel : Ibid, 19, 1926 ." Goldschmidt : Ibid, 20, 728 ; Noyes ; Am. Chem. J., 14, 226; -540. . 10 grams acetoxime. 20 grams sodium. 240 cc. absolute alcohol. Put in a 200 cc. round-bottomed flask 20 grams of sodium, connect with a long reversed condenser, and pour through the latter a solution of 10 grams of acet- oxime in 60 cc. of absolute alcohol. By means of a short tube, bent twice at right angles and passing through rubber stoppers, connect the top of the condenser with a U-tube containing 5 to 6 cc. of concentrated hydrochloric acid. Because of the low boiling-point of isopropyl amine this is necessary, but with amines of higher molecular weight it is not required. When the first violent action slackens, warm on an asbestos plate and add from time to time, more alcohol, whenever a crust forms on the sodium. About 240 cc. of alcohol will be required. When the sodium has all dissolved, add 40 cc. of water through the condenser, cool, and then distil off the alco- hol and isopropyl amine, collecting in a flask contain- ing 12 cc. of concentrated hydrochloric acid, including that from the []-tube. Evaporate to dry ness, and pre- serve the amine in the form of its chloride. Yield 8 to 10 grams. Isopropyl amine boils at 31.5, and has an ammoniacal, fishy odor. Its specific gravity is 0.690 at 18. The chloride is deliquescent and melts at i53-i55. The S 142 ORGANIC CHEMISTRY. chloroplatinate is difficultly soluble, and melts at 227- 228. The salt is easily prepared by adding chloropla- tinic acid, ("platinic chloride"), H 2 PtCl 6 , to a concen- trated solution of the chloride. It can be analyzed by careful ignition in a porcelain crucible. 54. Preparation of an Amine by the Reduction of a Cyanide. cw-Phenyl-ethyl-amine, C 6 H 5 CH 2 CH 3 NH a . ( 1 8 -amino-ethy Iphen . ) Literature. Cannizzaro : Ann. Chem. (Liebig), 96, 247; Mann ; Ber. d. chem. Ges., 14, 1645 ; Stadel : Ibid, 19, 1951 ; Hotter : Ibid, 20, 82 ; Spica, Columbo ; Gaz. chim. Ital., 5, 124 ; Bernsthen : Ann. Chem. (Liebig), 184, 304; Ladenburg: Ber. d. chem. Ges., 18, 2956 ; 8, 19, 782 ; Hoffmann : Ibid, 18, 2740 ; Hoogewerf, van Dorp; Rec. trat. chim des Pays-Bas., 5, 254; Fileti, Piccini: Ber. d. chem. Ges., 12,1700. 30 grams benzyl chloride. 38 cc. alcohol. 1 8 grams potassium cyanide. 17 grams water. 5 grams benzyl cyanide. 6 grams sodium. 70 cc. absolute alcohol. 8 cc. hydrochloric acid (sp. gr. i.io). Put in a round-bottomed flask 18 grams of pure pow- dered potassium cyanide, 17 cc. of water, 30 grams of benzyl chloride, and 38 cc. of alcohol. Connect with an upright condenser, and boil on a wire gauze or asbestos plate for 3 to 4 hours. By means of a separatory funnel separate the alcoholic solution, containing the benzyl cyanide, from the lower aqueous layer and distil the AMINES. 143 former. The alcohol and water may be distilled with advantage from a water-bath under diminished pressure and the heating continued till the residual liquid is dry (see 7, p. 36). In any case the portion boiling at 210 240 will, if dry, be sufficiently pure for this prepara tion .Yield of benzyl cyanide 20 to 22 grams. Put in a 200 cc. round- bottomed flask 6 grams of sodium, cut in small pieces, add a warm solution of 5 grams of benzyl cyanide in 30 cc. of absolute alcohol, connect with an upright condenser, and heat rapidly to boiling. Continue to boil and add more alcohol as necessary, in all 70 to 80 cc., till the sodium is dissolved. Distil off the alcohol and the phenylethylamine in a cur- rent of steam, distilling as long as the distillate comes over alkaline. Add to the distillate 8 cc. of hydro- chloric acid, evaporate to a small volume, filter, and evaporate to dryness. Transfer the residue to a small test-tube, dissolve in 2 to 3 cc. of hot water, cool, add 8 cc. of sodium hydroxide (3 cc. = i gram), and a few cc. of ether, and shake vigorously. Allow the ethereal layer to separate, and by means of a pipette with a fine capil- lary tube, remove as much as possible of the aqueous solution from below. Pour off the ethereal solution into a dry tube, rinse with a little ether, and dry the ethereal solution by adding solid caustic potash and leaving it for 24 hours. Transfer to a small (15 cc. or less) dis- tilling bulb, and distil the ether through a condenser and then the amine directly into a small preparation tube. Yield about 2\ grams of the chloride, and \\ grams of the distilled amine. 144 ORGANIC CHEMISTRY. This method of reducing cyanides led Ladenburg to the synthesis of cadaverin from trimethylene cyanide, CNCH 2 CH 2 CH 2 CN. With ethylene cyanide and phenyl cyanide it gives less satisfactory results, owing, in the latter case, to secondary reactions which give partly benzene and sodium cyanide and partly sodium benzoate and ammonia. Benzyl cyanide boils at 231.7. 6?-phenyl-ethylamine is a colorless liquid which has a slightly ammoniacal odor, and boils at 198. It has a specific gravity of 0.958 at 24.4. It is a strong base, is somewhat soluble in water, and is easily soluble in alcohol and ether. The chloride, C 6 H B CH 2 CH 2 NH 2 HC1, crystallizes from absolute alco- hol in leaflets or plates, which melt at 217, and dis- solve in 1 1 parts of water at 14. It is less easily solu- ble in hydrochloric acid, easily soluble in alcohol. The chloroplatinate is difficultly soluble in cold water. 55. Benzyl Amine. C 6 H 6 CH a NH 3 , Aminomethyl- phen. Literature. Mendius : Ann. Chem. (Liebig), lai, 144; Bam- berger, Lodter; Ber. d. chem. Ges, 20, 1709 ; Cannizzaro : Ann. Chem. (Liebig), 134, 128 ; Hofmann : Ber. d. chem. Ges., 18, 2738; Tafel : Ibid, 19, 1928; Curtius, L,ederer : Ibid, 19, 2463; Iveuchart, Bach : Ibid, 19, 2128; Goldschmidt: Ibid, 19, 3232; Mason: J. Chem. Soc., 63, 1313; Seelig : Ber. d. chem. Ges., 23, 2971 ; Hoogewerf, van Dorp : Rec. tran. chim. d. Pays. Bas., 5, 253 ; Delepine : Compt. rend., 120, 501 ; 124, 292. 50 cc. formaldehyde solution (40 per cent.). 50 cc. ammonia (sp. gr. 0.90). AMINKS. 145 10 gram hexamethlene amine. 10 grams benzyl chloride. 30 cc. chloroform. 1 6 grams double compound of hexamethylene amine with benzyl chloride. 45 cc. alcohol. 15 cc. concentrated hydrochloric acid. Put in a 150 cc. distilling bulb 50 cc. of a 40 per cent, solution of formaldehyde and add in small portions, cooling somewhat, 50 cc. of ammonium hydroxide (0.90). Heat for 5 to 10 minutes on a water-bath , put in the mouth of the bulb a rubber stopper bearing a fine capil- lary tube (see 10, p. 46), and distil as rapidly as possible from the water-bath, under diminished pressure, till the residue of hexamethylene amine appears dry. Rinse out the amine with a mixture of two volumes of ether with one volume of alcohol and- suck off on a Witt plate. Wash with a little ether and dry on the water-bath. 10 grams of the amine should be obtained. A small addi- tional quantity of amine may be obtained from the alco- hol-ether mother-liquors. Put in a small flask 10 grams of the hexamethylene amine, 30 cc. of chloroform, and 10 grams of benzyl chloride. Connect with an upright condenser, and boil gently on a water-bath for half an hour. Allow to cool, filter, and wash with a little chloroform. About 16 OTT r\ TT grams of the double compound, C 6 H 18 N 4 <;j * < 6 , should be obtained. An additional small amount of the compound will separate from the mother-liquors on standing. 146 ORGANIC CHEMISTRY. Put in a distilling bulb 16 grams of the double com- pound last mentioned, and 60 cc. of a mixture of three volumes of alcohol and one volume of concentrated hydrochloric acid. Connect with an upright condenser, and heat on a water-bath for an hour, then distil from OC H 2B the water-bath the methylenediethyl ether, which has been formed. Add to the residue 20 cc. of the same mixture of alcohol and hydrochloric acid, and heat again for an hour on the water-bath, allowing the methylenediethyl ether to distil through a condenser as it is formed. Then distil over a free flame till 20 to 25 cc. in all have passed over. Repeat this process a second time, and, if necessary, a third, or till the odor of the ether can no longer be detected in the distil- late. The complete decomposition of the double com- pound is essential to the success of the preparation. Transfer the residue in the bulb to an evaporating dish, and evaporate on the water-bath nearly or quite to dryness . Transfer the residue to a flask , add a strong solu- tion of sodium hydroxide in considerable excess, separate the benzyl amine by means of a separatory funnel, dry it by allowing it to stand with solid caustic potash, and distil. Yield 4 to 5 grams. In working with larger quantities the yield is somewhat better. The methylenediethyl ester, which is formed as a by- product, boils at 89, and has a specific gravity of 0.851 at o. It dissolves in n volumes of water at 18. Benzyl amine boils at 183, and has a specific gravity AMINES. 147 of 0.9826 at '% ' It is miscible in all proportions 4 with water, alcohol, and ether, but is separated from aqueous solutions on the addition of sodium hydroxide. It has a strong alkaline reaction, and absorbs carbon dioxide from the air. NOTE . An important modification of Hoffmann ' s reac- tion came to the author's notice too late for insertion at the appropriate place in this chapter (p. 133). Lengfeldt, Stieglitz, and Elizabeth Jeffreys have very recently shown (Ber. d. chem. Ges., 30, 898; see also Am. Chem. J., 15, 215, 504; 16, 307 ; 19, 295) that in the case of aliphatic amides of high molecular weights, where the reaction cannot be applied in its usual form owing to the formation of nitriles, the urethane can be obtained by dissolving the amide (i molecule) in 3 parts of methyl alcohol, adding a solution of sodium (2 atoms) in 25 parts of methyl alcohol, and dropping bromine (2 atoms) into the solution. After warming for ten minutes on the water-bath, the solution is acidified with acetic acid, evaporated, the inorganic salts removed with water and the urethane separated from unchanged amide by solution in warm ligroin. The urethane is decomposed by heating with concentrated sulphuric acid at i io-i2o for an hour, or, better, by distilling with three to four times its weight of slaked lime. RCONHBr+NaOCH s = RNHCOOCH 3 + NaBr. Urethane. RNHCOOCH 3 + Ca(OH) 2 = RNH 2 +CaCO s +CH 3 OH. CHAPTKR VI. Diazo, Hydrozo, Nitroso and Other Nitrogen Compounds* A considerable number of other nitrogen compounds beside amines and nitro derivatives are known. Most of these are obtained by reduction of nitro compounds, by oxidation of amines, or by condensations with the use of the compounds resulting from such reduction or oxi- dation. Unless otherwise stated, the following methods apply to the aromatic series only. In some cases simi- lar derivatives of the marsh gas series are known, but usually they require different methods of preparation. Azoxy compounds are formed by boiling nitro com- pounds with a solution of caustic potash in methyl or ethyl alcohol, or with a solution of sodium ethylate, or methylate, the alcohol acting as the reducing agent. 2 R N0 3 3O = R N N R. \/ O The method cannot be applied to compounds having a methyl group para to the nitro group, because conden- sation to derivatives of dibenzyl, C 6 H 5 CH 2 CH 3 C 6 H 6 , or stilbene, C 6 H B CH=CHC 6 H 5 , takes place. Azo compounds are prepared by the reduction of azoxy compounds by distillation with iron filings, by the direct reduction of nitro compounds with zinc dust and alcoholic potash, or by the oxidation of a hydrazo com- pound by means of the oxygen of the air acting on a solution in alcohol containing a little alkali. NITROGEN COMPOUNDS. 149 R N N R O = R N=N R. \/ O 2 R N0 2 40 = R N=N R. R NH NH R+O = R N=N R+H 9 O. Aminoazo, R N=N R NH 2 , and oxyazo (more correctly hydroxyazo), R N=N R OH, compounds are formed by the condensation of diazo compounds, with amines or phenols. As the condensation takes place usually in neutral, or slightly acid solutions, but does not, as a rule, occur in either strongly alkaline or strongly acid solutions, Bamberger supposes the reaction to take place between the diazo hydroxide and the other compound. (Ber. d. chem. Ges., 28, 444.) R N=N OH + H R NH 2 = R N=N R NH a + H 9 0. This kind of condensation takes place most readily with tertiary amines, and with primary metadiamines. Primary and secondary amines, on the other hand, con- dense in acetic acid solutions, with the formation of diazoamino compounds. R N=N OH + R NH, = R N=N NHR+H 9 O. These diazoamino compounds, when allowed to stand with cold dilute hydrochloric acid, or when warmed with the chloride of the amine, dissolved in the free amine, usually pass over into the corresponding amino-azo com- pound ; e. g. : C 6 H 5 N=N NHC 6 H 5 C.H. N=N C.H.NH,. Diazoamino benzene. Aminoazobenzene. 150 ORGANIC CHEMISTRY. This combination (" Kuppelung ") of diazo compounds with amines and phenols, and the transformation of diazoamino into aminoazo compounds, are of great technical importance. O. N. Witt has pointed out that dye-stuffs must have two characteristics ; they must have a color group (" chromophor " ) , e. g., the azo, or nitro group, and they must also have a salt-forming group ("auxochrome"), e. g., hydroxyl, or the amino group, which will enable the substance to combine with the fiber in dyeing. The azo compounds are all of them colored, but only those of them which contain some "auxochrome " group as well can be used in dyeing. All organic coloring matters are changed to colorless compounds by reduction. These colorless compounds have received the general name of ' ' leuco ' ' compounds ("L,eukoverbindungen," from Greek XSVKOS, white). The leuco compounds corresponding to the azo bodies are the hydrazo compounds. These may be prepared from the azo compounds by reduction with alcoholic ammonium sulphide, or with zinc dust and alcoholic potash or soda. They may also be prepared by direct reduction of nitro compounds with zinc dust and alco- holic potash. R N=N R+ 2H = R NH NH R. 2 R N0 a + ioH = R-NH NH R + 4 H 2 O. Diazo compounds are formed by the action of nitrous acid on amines in acid solutions. RNH 2 HC1 + HNO 2 = R N=N+2H,O. Cl NITROGEN COMPOUNDS. UNIVERSITY 151 On account of their instability, diazo compounds are not usually separated, but are used for synthetical pur- poses immediately after preparation. Several illustra- tions of such use have already been given. (See pp. 42, 114, 224, and 168.) Hydrazines are prepared by the reduction of diazo compounds with stannous chloride, with acid sodium sulphite, or with acid sodium sulphite, zinc dust and acetic acid, followed by the decomposition of the result- ing sulphonic acid with hydrochloric acid. R NEEEN + 2SnCl, + 4HC1 = R NH NH,HC1 + Cl 2SnCl 4 . R N=N + HNaSO s = R N=N SO 3 Na + HC1. Cl R_N=rN S0 3 Na+2H = R NH NH SO 3 Na. R NH NH S0 3 Na + HC1+H 2 O= R NH NH 2 HC1 + NaHS0 4 . Hydrazones are formed by the condensation of hydra - zines with aldehydes or ketones, usually in neutral or acetic acid solution. R /R R _ N H NH 3 + ;CO = R NH N=C' + H 2 O. R X N R Hydrazones are also formed by the condensation of diazo compounds with bodies containing a methylene group between two carboxyl groups. Owing to a differ- ent view of the structure of these compounds, which J 5 2 ORGANIC CHEMISTRY. prevailed before they had been fully studied, they are frequently called azo compounds. .CO 2 C 2 H 5 C 6 H 6 N=NOH + CH' = X C0 2 C 2 H 6 OH H / / C 6 H 6 NH N C CO 2 C Q H 6 C0 2 C 2 H 5 x eo t c,H. C 6 H 6 NH N=C ( + H 2 0. X C0 2 C 2 H 6 Hydrazone of mesoxalic acid. On the supposition that the structure was represented X C0 2 C 2 H 6 by the formula C 6 H 5 N=N CH( , this was X C0 2 C 2 H B called benzeneazomalonic ester, a name still used. Hydrazides are formed by the condensation of hydra - zines, with bodies containing hydroxyl, the condensa- tion taking place readily only when the hydroxyl is more or less acid in its properties. R NH NH 2 + RCOOH = R NH NH>C=O+ H 2 O. R The name is given from the analogy with amides. Osazones are formed by the action of an excess of CHOH phenyl hydrazine on bodies containing the group | CO NITROGEN COMPOUNDS. 153 A part of the phenyl hydrazine combines at once to form a hydrazone, a second part oxidizes the alcoholic group to a ketonic or aldehyde group, and the latter reacts with more of the hydrazine, giving finally the group, C=N NHC 6 H 5 | . The osazones have been of especial C=N NHC 6 H 6 importance in the study of sugars. 56. Preparation of a Hydrazo Compound. Hydrazo- benzene, C 6 H 6 NH NH C e H 6 . Literature Hofmann : Jsb. d. Chem., 1863, 424; Alexejew : Ztschr. Chem., 1867, 33 ; 1868, 497 ; B. Krdmann : Ztschr. angew. Chem., 1893, 163. 30 grams nitrobenzene. 200 cc. alcohol. 40 cc. sodium hydroxide (3 cc.= i gram). 45 grams zinc dust. Put in a 500 cc. flask 200 cc. of alcohol, 30 grams of nitrobenzene, and 40 cc. of a solution of caustic soda (3 cc.= i gram). Heat on a water-bath to about 75, put- ting in the mouth of the flask a cork bearing a tube to act as an air condenser. Add a small amount of zinc dust, shake and add more, in small portions, till the reaction begins. If the action becomes violent, check it by dipping the flask in cold water. Continue the warm- ing and addition of zinc dust till the solution becomes nearly colorless. Filter hot on a plate, cool quickly, 154 ORGANIC CHEMISTRY. filter off the hydrazobenzene as rapidly as possible, wash with a little alcohol, transfer it to a flask, and add at once some alcohol containing a little ammonium sul- phide to prevent oxidation. Boil the residue of zinc dust with the mother liquors, filter and separate the hy- drazobenzene as before, and repeat a third time. Then recrystallize the whole from hot alcohol containing am- monium sulphide, working as rapidly as possible, to prevent oxidation, and finally dry the product in a vacuum desiccator, over sulphuric acid. In recrystal- lizing, water may be added to the hot, filtered alcoholic solution till it begins to be turbid, to cause the more complete separation of the hydrazobenzene, and the product may be washed with dilute, instead of pure alco- hol. It may also be crystallized from ligroin. Yield 19 to 20 grams. Hydrazobenzene crystallizes in colorless leaflets, which melt at 131. It is easily soluble in alcohol, and ether, almost insoluble in water. It is very easily con- verted into azobenzene, even by the oxygen of the air. By warming with hydrochloric acid, it is converted into benzidine, NH 2 C 6 H 4 C 6 H 4 NH 2 . It is decomposed by htat into azobenzene and aniline. 57. Preparation of an Azo Compound. Azobenzene, C 6 H 6 N=N C 6 H 5 . Literature. Mitscherlich : Ann. Chem. (Liebig), 12, 311; Zinin: J. prakt. Chem. 36, 93, (1845}; Claus: Ber. d. chem. Ges., 8, 37 ; Griess : Ibid, 9, 132; Frankland and Louis : J. Chem. Soc., 37, 560, (1880*) ; Spiegel : Ber. d. chem. Ges., 18, 1481 ; Mills : J. Chem. Soc., 65, 51, (1894). NITROGEN COMPOUNDS. 155 10 grams hydrazobenzene. 170 cc. alcohol. i cc. sodium hydroxide (3 cc. = i gram). Put in a 300 cc. flask 10 grams of hydrazobenzene, 170 cc. of alcohol, and i cc. of a solution of caustic soda. Close the flask with a stopper bearing an upright con- denser, and a glass tube leading nearly to the bottom of the flask. Heat on a water-bath and draw or force through the solution a slow current of air for three to four hours. Filter, if necessary, distil off most of the alcohol and allow the azo-benzene to crystallize after adding a little water. Yield 7 to 8 grams. Azobenzene crystallizes in red plates, which melt at 68. It boils without decomposition at 295. It is sol- uble in 12 parts of alcohol at 16. 58. Preparation of an Amino-azo Compound through the Diazoamino Compound. /-Aminoazobenzene, CH ^N^N-CeH, (i). M^^HH, ( 4 ). Literature. Griess : Ann. Chem. (lyiebig), 121, 258; Staedel and Bauer.; Ber. d. chem. Ges., 19, 1952 ; Niementowski and Roszkowski : Ztschr. phys. Chem., 22, 145. 50 cc. aniline. 60 cc. concentrated hydrochloric acid. 13 grams aniline chloride. 200 cc. water. 3.5 grams sodium nitrite. 17.5 cc. water. 10 grams crystallized sodium acetate. 156 ORGANIC CHEMISTRY. 5 grams diazoaminobenzene. 15 grams aniline. 3 grams aniline chloride. Prepare some aniline chloride by dissolving 50 cc. of aniline in 60 cc. of concentrated hydrochloric acid, cool- ing thoroughly, filtering with a plate on a hardened fil- ter, and drying on the water- bath. Dissolve 13 grams of the aniline chloride in 200 cc. of water, bring the temperature to 25, and add, with stir- ring, 3.5 grams of sodium nitrite, dissolved in 17.5 cc. of water. Keep the temperature at 27-3O by cooling, if necessary. Add, at once, a previously prepared solu- tion of 10 grams of crystallized sodium acetate, stir thoroughly and allow the whole to stand for 15 minutes. Filter off the diazoaminobenzene, wash and dry in vacuo over sulphuric acid. The yield is 9 to 10 grams. The body may be crystallized from gasoline, or ligroin, if desired. Dissolve 5 grams of the dry diazoaminobenzene in 15 cc. of aniline, in a small flask, add 3 grams of dry, powdered aniline chloride, warm in a water-bath at 40, for an hour, and allow the mass to stand for a day, or until the solution no longer evolves nitrogen, when a small portion is warmed with alcohol and hydrochloric acid. Add 40 cc. of hydrochloric acid (sp. gr. i.io), cool, filter, and wash with dilute hydrochloric acid. Dissolve the chlo- ride of the aminoazobenzene in about 500 cc. of hot water, adding enough hydrochloric acid to prevent dis- sociation, but not more. Filter, if necessary, and add 20 to 25 cc. of concentrated hydrochloric acid. On cool- ing, the chloride will separate almost completely in crys- NITROGEN COMPOUNDS. 157 talline form. Filter, wash with dilute acid, and dry. If the free amiuoazobenzene is desired, it can be ob- tained by warming the chloride with twice its weight of alcohol, and adding concentrated ammonia till it dis- solves. On further addition of water, the base separates in yellow leaflets, which may be recrystallized from ben- zene. Yield of the chloride about 4^ grams. /-Aminoazobenzene crystallizes in orange-yellow, rhombic prisms, which melt at 127, and boil without de- composition at 360. It is almost insoluble in water, easily soluble in alcohol and ether. It is reduced by tin and hydrochloric acid to aniline and paraphenylenedi- amine. The chloride is dissociated by water. It is known as aniline yellow, and in slightly acid solution colors wool and silk intensely yellow. Diazoaminobenzene melts at 98, and is slightly explo- sive. 59. Preparation of an Azo Compound by the Combi- nation of a Diazo Compound with an Amine. benzene-azo-<*-naphthylamine, SO 3 H NH a N = N- (4) -Sulphobenzene-azo- (4) -amino- ( i ) -naphthalene. 158 ORGANIC CHEMISTRY. Literature. Griess : Ber. d. chem. Ges., 12, 427. 5 grams sulphanilic acid. 10 cc. sodium hydroxide (10 per cent.). 200 cc. water. 10 cc. hydrochloric acid (sp.gr. i.i). 1.7 grams sodium nitrite. 8.5 cc. water. 3.5 grams tf-naphthylamine. 6 cc. hydrochloric acid (sp. gr. i.i). 200 cc. water. Dissolve 5 grams of sulphanilic acid in 10 cc. of sodium hydroxide and 20 cc. of water, by warming in a flask. Cool, dilute to about 200 cc., and add 1.7 grams of sodium nitrite, dissolved in 8.5 cc. of water. Dissolve 3.5 grams of or-naphtylamine in 6 cc. of hydrochloric acid and 200 cc. of hot water. Cool, and add the solu- tion of paradiazosulphobenzene. Mix thoroughly by pouring from one beaker to another and back several times. Allow to stand for several hours, then heat on the water-bath, or over the free flame, till the precipitate becomes crystalline, and much less voluminous. Filter hot, and wash. -Naphthylamine-azobenzene-/-sulphonic acid crys- tallizes in microscopic needles of a dark violet color. It is almost insoluble, even in boiling water, and is also very difficultly soluble in alcohol. The dilute solutions are of a bright red or pink color and, since the body is formed quantitatively when nitrous acid acts on an excess of an acid solution containing sulphanilic acid and <*-naphthyl- NITROGEN COMPOUNDS. 159 amine, it is often used for the determination of nitrites in potable waters. Since the body is a sulphonic acid, it dissolves to clear orange-red solutions in very dilute solutions of caustic soda, or ammonia, but the addition of more sodium hy- droxide to such solutions, even if quite dilute, will cause the precipitation of the red, crystalline, sodium salt, C^JH.SO.Nn. 60. Preparation of a Salt of a Diazo Compound. Diazobenzene chloride, C 6 H B N=N. Cl Literature. Griess : Ann. Chem. (Liebig), 113, 201 ; 117, i ; 121, 257; 137, 39; Ber. d. chem. Ges., 24, R., 10(57; V. Meyer and Ambiihl : Ibid, 8, 1073 ; Knoevenagel : Ibid, 23, 2994 ; Hausser and Miiller : Bull. Soc. Chim. [3], 9, 353, (/pj). 2 grams aniline chloride. 8 cc. alcohol. 2 cc. (1.8 grams) amyl nitrite, or 1.3 cc. (1.23 grams) ethyl nitrite. Dissolve 2 grams of aniline chloride in 8 cc. of abso- lute alcohol in a test-tube. Cool with ice water, add a drop of concentrated hydrochloric acid, and then very slowly, with cooling and stirring, 2 cc. of amyl nitrite, or 1.3 cc. of ethyl nitrite. 1 Allow to stand in ice-water 1 Ethyl nitrite may be prepared as follows : Prepare a solution of 10 grams of sodium nitrite in 50 cc. of water and 5 cc. of alcohol, and a second so- lution of 5 cc. of concentrated sulphuric acid, 50 cc. of water and 5 cc. of alco- hol. Cool each to o e , and add the acid solution to the nitrite solution, with a pipette, which is inserted beneath the surface of the liquid, cooling thor- oughly. After a few minutes, separate the ethyl nitrite, which rises to the top of the liquid, using a cold separatory funnel. Keep the nitrite in a tube, l6o ORGANIC CHEMISTRY. for a short time, and then filter off the diazobenzene chloride and wash it with a very little alcohol, contain- ing a little hydrochloric acid, and with ether. Separate into several portions and dry on filter-paper, in the air. On account of the explosive character, the portions dried should not exceed 0.1-0.2 gram each. Small portions may be warmed with water, alcohol, or concentrated hydrochloric acid, to illustrate the decom- positions of the body, but for most purposes of synthesis, the free diazo compounds, or salts, are not prepared. See pp. 42, 114, 124, and 168. 61. Preparation of a Hydrazine. Phenyl hydrazine, C 6 H 6 NHNH 2 . Literature. E. Fisher : Ann. Chem. (Liebig), 190, 67 ; Ber. d. chem. Ges., 17, 572 ; V. Meyer, u. L,ecco : Ibid, 16, 2976 ; Reych- ler : Ibid, 20, 2463 ; Ibid, 26, 19 ; Altschul : Ibid, 25, 1849. 1 8. 6 grams aniline. 1 60 cc. hydrochloric acid (sp. gr. 1.19). 14 grams sodium nitrite. 70 cc. water. 50 grams tin. 150 cc. hydrochloric acid (sp. gr. 1.19). 40 cc. sodium hydroxide (3 cc.= i gram), Prepare a solution of stannous chloride by dissolving 50 grams of feathered tin in 150 cc. of concentrated hy- surrounded with ice. It boils at 17. If larger quantities of the nitrite are desired, the solutions may be prepared in the proportions given, and the ni- trite solution put in a flask or distilling bulb, connected with a condenser, fed with ice-water. The solutions should be at 20 "-25. On running the acid solution in slowly, the ethyl nitrite will distil over, and may be collected in a receiver, surrounded with ice. (Wallach and Otto : Ann Chem. (lyiebig), 253, 251.) NITROGEN COMPOUNDS. l6l drochloric acid, or by dissolving 120 grams of crystal- lized stannous chloride in 100 cc. of concentrated hydro- chloric acid. Add 18.6 grams of aniline (i mol.) to 100 cc. of concentrated hydrochloric acid, stirring vigorously. Set the beaker in ice-water, or a freezing mixture, and when the temperature has fallen nearly to o, add 150 grams of ice, and then, from a drop funnel, drawn to a narrow tube at the end, or having a narrow tube attached, and dipping nearly to the bottom of the solution, add slowly and with constant stirring, a cold solution of 14 grams (i mol.) of sodium nitrite in 70 cc. of water. The temperature should not rise above 5. When all has been added, the solution, after standing two minutes, should react for nitrous acid, when a drop is diluted and tested with starch iodide paper. If it does not, a little more sodium nitrite must be added, using the least possible excess. As soon as possible, add slowly, with stirring, the solution of stannous chloride, which must, meanwhile, have been cooled to o, or be- low. Add, if necessary, more ice, to keep the tempera- ture below 10 during the addition of the stannous chlo- ride. Stir very thoroughly, and allow to stand for an hour. Filter off the chloride of the phenyl hydrazine, which separates, suck and press it as free as possible from the mother liquors, and wash once with a small amount of dilute hydrochloric acid. Evaporate the fil- trate to about 150 cc., best in a large beaker heated over a free flame on wire gauze. Cool, and separate the chlo- ride of the phenyl hydrazine, which crystallizes, as be- fore. Dissolve the chloride in a small amount of warm 162 ORGANIC CHEMISTRY. water, add an excess of a strong solution of sodium hy- droxide, cool, collect the phenyl hydrazine with a little ether, separate, distil off the ether, dry by allowing to stand in vacua over sulphuric acid, or dry with fused caustic potash, pour off and distil, best under diminished pressure. Some ammonia is formed during the distilla- tion, which may be removed by allowing the product to stand over sulphuric acid. The phenyl hydrazine may be further purified by a second distillation, or by allow- ing it to solidify at a low temperature, and pouring off the liquid portion. Yield, about 18 grams. Phenyl hydrazine boils at 242, and solidifies at a low temperature, melting at 19. Its specific gravity is 1.097, at 23. It is a violent poison. On adding a so- lution of phenyl hydrazine acetate to a hot solution of copper sulphate, it is oxidized with the formation of benzene. With aldehydes, ketones, and sugars, phenyl hydrazine gives characteristic condensation products. See 62, below, and 74, p. 190. 62. Preparation of an Osazone. Glucosazone, CH 2 OH CHOH CHOH (Dextrosazone, levulosazone). CHOH I C=N NHC 6 H 6 CH=N NHCJL NITROGEN COMPOUNDS. 163 t Literature. E. Fischer: Ber. d. chem. Ges., 17, 580; Jaksch : Ztschr. anal. Chem., 24, 478; Beythien : Ann. Chem. (L,iebig), 255, 218. 2 grams glucose. 4 grams phenyl hydrazine. 10 cc. acetic acid (30 per cent.). 50 cc. water. Dissolve 2 grams of glucose in 50 cc. of water, add a solution of 4 grams of phenyl hydrazine in 10 cc. of acetic acid, and heat on a water-bath for two hours. Cool, fil- ter off the glucosazone and recrystallize it from 80 per cent, alcohol. Glucosazone melts, when heated quickly, at 206, and crystallizes in characteristic yellow needles. With di- phenyl hydrazine glucose gives an even more character- istic hydrazone. (Stahel : Ann. Chem. (L,iebig), 258, 244.) VII. Alcohols and Phenols. Alcohols are prepared from the halogen derivatives of hydrocarbons, by treatment with water, potassium car- bonate and water, silver oxide and water, or potassium or silver acetate, followed by saponification of the acetic ester of the alcohol, which is formed. The iodides re- act more readily than other halogen derivatives, but bromides are often used. 2 RI + K 2 C0 3 + H 2 = 2ROH + 2 KI + CO 3 . RI + AgC 3 H 8 O a = R O C 2 H 3 + Agl . RO C 3 H 3 O + KOH = R OH + KC 2 H 3 O a . From unsaturated hydrocarbons alcohols can be ob- tained by dissolving them in concentrated sulphuric acid, diluting, and distilling. The method gives second- ary and tertiary alcohols in cases where their formation is possible. C n H 2n + H 2 S0 4 = C n H 2n+I HS0 4 . C n H an+I HSO 4 + H 2 O = C n H 2n+I OH + H 2 SO 4 . Aldehydes may be reduced to primary alcohols, and ketones to secondary alcohols. The reducing agents most often used are sodium amalgam in aqueous solu- tions, sodium in alcoholic or moist ethereal solutions, or zinc dust and glacial acetic acid. The last method gives an acetate which requires saponification. Amines may be converted into alcohols by the action ALCOHOLS AND PHENOLS. 165 of nitrous acid in aqueous solutions. In the aromatic series a diazo compound is first formed. In the aliphatic series, and especially in cyclic compounds, unsaturated hydrocarbons are also formed, and interfere seriously with the yield. RNH a + HNO a = ROH + N a + H a O. R< NH, + HNO = R " + N ' + 2H '' In the aromatic series sulphonic acids, and in many cases halogen derivatives, may be converted into phenols by fusion with potassium hydroxide. The re- action is accompanied, in some cases, by a rearrange- ment, which interferes with its reliability for the determi- nation of structure. RSO a OH + 2KOH = ROH + K a SO 3 + H a O. Glycols, that is, alcohols having two hydroxyl groups combined with adjacent carbon atoms, may be prepared, in some cases, by oxidizing olefines with a cold solution of potassium permanganate. R CH R CHOH || + + H a O = | R CH R CHOH This reaction is of greater importance for the prepar- ation of dihydroxy acids than for the preparation of glycols, however. (See Fittig : Ber. d. chem. Ges.,27, 2670.) Many aromatic aldehydes, on treatment with potas- sium hydroxide and water, are converted into a mixture 1 66 ORGANIC CHEMISTRY. of the potassium salt of the corresponding acid, and the corresponding alcohol. 2RCHO + KOH = RCH 2 OH + 63. Preparation of a Diacid Alcohol from a Halogen Derivative ot a Hydrocarbon. Bthylene glycol, CH 2 OH | (Ethanediol). CH 2 OH Literature. Wurtz : Compt. Rend., 43, 199, (y#5<5) ; Jeltekow : Ber. d. chem. Ges., 6, 558; Niederist ; Ann. Chem. (Liebig), 186,393; 196, 354; Erlenmeyer : Ibid, 192, 355; Wagner: Ber. d. chem. Ges., 21, 1234, 3346; Haworth and W. H. Perkin, Jr. : J. Chem. Soc., 69, 175. 18.8 grams ethylene bromide (three times repeated) . 13.8 grams potassium carbonate (three times repeated) . 100 cc. water. Put in a 200 cc. flask 18.8 grams of ethylene bromide, 13.8 grams of dry potassium carbonate, and 100 cc. of water. Connect with a reversed condenser, and boil gently till the ethylene bromide disappears, usually eight to ten hours. Add the same amounts of ethylene bromide and potassium carbonate, and boil as before. Repeat a third time. The addition of a few small pieces of wood will help to prevent bumping. Some vinyl bromide, CH 2 -CHBr, escapes during the boiling, and can, if desired, be converted into tribromethane, by leading through a bottle containing bromine. If large amounts of glycol are desired, the addition of ethylene bromide and potassium carbonate may be repeated six ALCOHOLS AND PHENOLS. 167 times instead of three, but in that case it is necessary to filter off the potassium bromide, which separates on cooling the solution after each boiling. ' Concentrate the solution in vacuo over sulphuric acid, pour off from the potassium bromide which separates, wash the latter with a little absolute alcohol, and submit to fractional distillation. Or the aqueous solution may be distilled at once, best under diminished pressure, and the distillate used in a new preparation, since the glycol is quite volatile with water vapor. Ethylene glycol is a colorless liquid, with a sweet taste. It boils at 197, and solidifies in a freezing mix- ture. It is miscible in all proportions with water and alcohol, but not with ether. Platinum black oxidizes it CO 2 H to glycollic acid, | . CH 2 OH 64. Preparation of an Alcohol by the Reduction of a Ketone. Phenyl methyl carbinol, p 6 J? 5 >CHOH, phen- CH 3 ethylol (i). Literature. Radziszewski : Ber. d. chem. Ges.,7 141 ;Berthe- lot: Ztschr. Chem., 1868, 589; Emmerling, Engler : Ber. d. Ges., 4, 147 ; 6, 1006. 10 grams acetophenone. 100 cc. ether. 30 cc. water. 8-10 grams sodium. Put in a 200 cc, flask 10 grams of acetophenone, 1 30 cc. 1 This may be prepared exactly as directed for benzophenone (71, p. 184), 1 68 ORGANIC CHEMISTRY. of water, and 100 cc. of ether. Add sodium in small pieces, shaking gently, and cooling the flask with water, till the ethereal solution no longer gives a turbidity when a drop of it is put in a test-tube with a dilute solu- tion of phenyl hydrazine acetate (see 75, p. 191). 8-10 grams of sodium will usually be required. Toward the close more water may be added if the solution of the sodium takes place too slowly. Separate the ethereal solution, distil off the ether, dry the residue in vacua over sulphuric acid, or by heating on a water-bath under diminished pressure with a capillary (pp. 36 and 46), and distil. Yield 6 to 7 grams. The yield is diminished by the formation of the pinacone, 9?5*>C C OH OH Phenyl-methyl-carbinol boils at 2O2-2O4, and has a specific gravity of 1.013. 65. Preparation of a Phenol by the Decomposition of an Amine through the Diazo Compound. Paracresol, C H <C SO 3 Na. Double compound vith hydrogen sodium sulphite. >CO+C 6 H 6 NHNH 2 = ^>C=N NHC 6 H B +H 2 0. Phenyl hydrazone. *>CO + NH 2 OH = *>C Oxime. |>CO+ NH 2 NH CO NH 2 = >C=N NH CONH 2 +H 2 O. Semicarbazoue. 70. Preparation of an Aldehyde by Oxidation of a Primary Alcohol. Acetaldehyde, CH.C^Q (Etha- nol). Literature. Liebig : Ann. Chem. (Liebig), 14, 133; Ritter: Ibid, 97, 369; Stadeler : Jsb. d. chem., 1859, 329 ; J. prakt. Chem., 76, 54, (1859); Bourcart : Ztschr. anal. Chem., 29,609; Rogers: J. prakt. Chem., 40, 244, (1847); Weidenbusch : Ann. Chem. (Liebig), 66, 152; Ritter: Ibid, 97,369; Tollens: Ber. d. chem. Ges., 14,1950; Orndorff and White : Am. Chem. J., 16,43. 150 grams (81 cc.) concentrated sulphuric acid. 300 cc. water. 182 ORGANIC CHEMISTRY. 100 grams sodium pyrochromate. 150 cc. water. 75 grams (95 cc.) alcohol. Put in a one liter distilling bulb 300 cc. of water, and 150 grams (81 cc.) of concentrated sulphuric acid. Dis- solve loo grams of sodium pyrochromate in 150 cc. of water, and add 75 cc. of alcohol. Put a stopper bearing a separatory funnel in the mouth of the distill- Fig. 22. ing bulb, and connect a second quarter liter distilling bulb to its side tube with a rubber stopper. Connect the side tube of the second bulb to a condenser which is directed upward, by running the side tube into a piece of rubber tubing drawn over the lower end of the con- denser. Connect the upper end of the condenser with two Drechsel wash-bottles, each containing about 25 cc. of dry ether. Surround the latter with a freezing mixture. Put the small distilling bulb into a dish con- ALDEHYDES, KETONES, AND DERIVATIVES. 183 taining water at 45 50, and feed the condenser with water at 30. Heat the dilute sulphuric acid nearly to boiling, remove the flame, and drop in the pyrochromate mixture slowly. The reaction may proceed as rapidly as is possible without escape of aldehyde through the ether. Outside heating is not usually necessary after the reaction has commenced. When all the mixture has been added and the alde- hyde driven over by heating for a short time, disconnect the wash bottles, transfer the ethereal solution to a flask, set the latter in a freezing mixture, and pass in ammonia gas, generated by boiling strong aqua ammonia (0.90 sp. gr.) , and dried by passing it over quicklime, or soda- lime in a drying cylinder. Use a wide delivery tube for the gas to prevent its being stopped by the alde- OTT hyde ammonia, CH 8 CH<,^Tj , which is formed. Pass the gas till the solution smells of ammonia strongly, and allow the whole to stand for an hour. Filter off the crystals, and allow them to stand on filter paper for a short time. They can be kept for some time in tightly stoppered tubes or bottles, containing ammonia gas. Yield about 15 grams. Aldehyde may be prepared from them by dissolving them in their own weight of water, and dropping the solution into 4 parts of 50 per cent, sulphuric acid, con- densing the aldehyde which is generated, with a con- denser containing ice-water, and collecting in a flask surrounded with a freezing mixture. Aldehyde boils at 21, and has a specific gravity of 184 ORGANIC CHEMISTRY. 0.7951 at 10. When warmed with caustic potash it is converted into a resin. It reduces a cold ammoniacal solution of silver nitrate (3 grams AgNO 3 , 33 cc. NH 4 OH, sp. gr. 0.90, 30 cc. 10 per cent, sodium hydroxide), a general reaction for aldehydes. A drop of concentrated sulphuric acid converts it into paraldehyde, C 6 H 12 O 8 , which melts at 10.5, and boils at 124. Hydrochloric acid gas converts it into a mixture of metaldehyde, C 6 H 12 O S , and paraldehyde. Metaldehyde decomposes on standing, being converted partly into paraldehyde and partly in tetraldehyde, C 8 H 16 O 4 . Paraldehyde and metaldehyde are probably stereomeric compounds. 71. Preparation of a Ketone by Condensation of an Acid Chloride with Benzene by Means of Aluminium Chloride. Benzophenone, C 6 H 6 COC 6 H B . (Diphenyl- methanone.) Literature. Peligot : Ann. Chem. (Liebig), 12, 41 ; Chancel : Ibid, 72, 279; Otto : Ber. d. chem. Ges., 3, 197 ; Friedel, Crafts : Ann. chim. Phys., [6], 1,510, 518; Zincke : Ann. Chem. (Lie- big), 159, 377 ; Friedel, Crafts, Ador : Ber. d. chem. Ges., 10, 1854; Stockhausen and Gattermann : Ber. d. chem. Ges., 25, 3521; Radziewanowski : Ibid, 27, 3235; 28, 1135; Crafts: Am. Chem. J., 5, 324. 20 grams benzene. 20 grams benzoyl chloride. 100 grams carbon disulphide. 20 grams aluminium chloride. Put in a flask 20 grams of benzene, 20 grams of ben- zoyl chloride, and 100 grams of carbon disulphide. Add in small portions, during about ten minutes, 20 grams ALDEHYDES, KETONES, AND DERIVATIVES. 185 of finely powdered aluminium chloride . ( See 84, p . 211.) The chloride should be exposed to the air as little as pos- sible. Connect with a reversed condenser, and heat on the water-bath for two to three hours, or till the evolution of hydrochloric acid nearly ceases. Distil off the carbon disulphide, and pour the residue into 300 cc. of water in a flask, cooling, if necessary. Add TOCC. of concentrated hydrochloric acid, and pass a rapid current of steam through the liquid for a short time to expel the rest of the benzene and carbon disulphide. Collect the benzo- phenone with some ether, separate, wash the ethereal solution by shaking it several times with water, and with a solution of sodium hydroxide, dry it with calcium chloride, and fraction the residue, after distilling off the ether, using a small distilling bulb, and collecting the distillate directly in a test-tube, or preparation tube, without using a condenser. Yield 20 to 21 grams. Benzophenone melts at 48.5, and boils at 303.7 under 723.05 mm. 304-5 735-45 305-5 750.91 306.1 " 760.32 " 306.4 " 765.06 " This table is of especial value for testing thermome- ters. (See p. 16.) When benzophenone is warmed with hydroxylamine hydrochloride, caustic soda in excess, and alcohol, for two hours, an oxime melting at 140 is formed. If this oxirne, dissolved in dry ether, is treated successively with one and a half times its weight of phosphorus pentachloride, 1 86 ORGANIC CHEMISTRY. and with water, it is converted into benzanilide (Beck- mann's rearrangement). C e H 6 C C 6 H 6 +PC1 6 = C 6 H 6 C C 6 H 5 +POC1 3 +HC1 II II NOH N Cl C 6 H B C C e H 6 = C P H 6 C Cl II II N Cl N C 5 H C 6 H B C Cl + H 2 O = C B H B C=O II I +HC1. N C 6 H 6 HN C 6 H 5 The study of this reaction has been of great value in the development of theories about the stereochemistry of nitrogen. Unsymmetrical oximes which occur in two forms, as, for instance, monobrombenzophenone oxime, ' C 6 H 4 BrCC 6 H 6 , may be rearranged in this manner, and II NOH each form gives a different product ; viz. , brombenzoyl- anilide and benzoylbromanilide. C 6 H 4 Br C C 6 H B C 6 H 4 BrCONHC 6 H B . II NCI C 6 H 4 Br C C 6 H B * C fl H 5 CONHC 6 H 4 Br. II Cl N The two compounds can be distinguished by their saponification products. ALDEHYDES, KETONES, AND DERIVATIVES. 187 72. Preparation of an Aldehyde by Treatment of a Monochlor Derivative of an Aromatic Hydrocarbon with a Nitrate. Benzaldehyde, C 6 H 6 C^Q. (Oil of bitter almonds.) Literature. Liebig, Wohler : Ann. Chem. (Liebig), 22, i; Cannizzaro : Ibid, 88, 180 ; Dumas, Peligot : Ibid, 14, 40 ; Guck- elberger : Ibid, 64, 60, 72, 86 ; L,auth, Grimaux : Bull. Soc. Chim., 7, 106 ; Baeyer : Ann. Chem. (Liebig), 140, 296 ; Piria : Ibid, 100, 105; Ivitnpricht: Ibid, 139, 319; Anschiitz ; Ibid, 226, 18. 40 grams benzyl chloride. 40 grams barium nitrate. 300 cc. water. Put in a 500 cc. round-bottomed flask 40 grams of benzyl chloride, 40 grams of barium nitrate (or 30 grams calcium nitrate, prepared by treating an excess of cal- cium carbonate with the theoretical amount of nitric acid, and filtering), and 300 cc. of water. Connect with an upright condenser, best with a rubber tube slipped over the neck of the flask, the condenser reaching well down into the neck of the latter, so that the nitrous fumes evolved will come but little in contact with the rubber. The connection must be tight. Put in the top of the condenser a rubber stopper bearing a tube, which reaches down into the liquid, and also a tube which will convey the gases coming from the condenser to the bottom of a 150 cc. bottle, or, better, of a large tube, closed below. Pass through the first tube a slow current of carbon dioxide, and boil the contents of the flask gently on a wire gauze for six to eight hours, or 1 88 ORGANIC CHEMISTRY. till the odor of the benzyl chloride nearly, or quite dis- appears. Some such means as that described for the exclusion of the air is essential to prevent the oxidation of the aldehyde to benzoic acid. Extract the benzaldehyde with ether, distil off the latter, and shake the residue with three or four times its volume of a strong solution of acid sodium sulphite, 1 in a stoppered bottle. After some time, filter off the bi- sulphite compound, and wash successively with a very little water, alcohol, and ether. Put the compound in a distilling bulb with an excess of a strong solution of sodium carbonate, and distil with steam. Extract the benzaldehyde from the distillate with ether, dry with calcium chloride, and distil. Yield 10 to 15 grams. Benzaldehyde melts at 13. 5, and boils at 179. It has a specific gravity of 1.0504 at 15. It oxidizes slowly on standing in the air, when pure. It is more sta- ble when it contains hydrocyanic acid, which is usually added to the commercial article for this reason. It dis- solves in 300 parts of water, but is easily soluble in alco- hol, and ether. 73. Condensation of an Aldehyde with Itself by Means of Potassium Cyanide. Benzoin, C 6 H B CHOHCOC 6 H 5 . Literature. Liebig and Wohler : Ann. Chem. (Laebig), 3, 276; Zincke: Ibid, 198, 151; Papcke : Ber. d. chem. Ges., 21, 1335 ; A. Smith and Ransom : Am. Chem. J., 16, 108. 1 This must be freshly prepared by passing sulphur dioxide into a mix- ture of acid sodium carbonate with three parts of water, till the solution smells strongly of the gas. For sulphur dioxide, see p. 172. ALDEHYDES, KETONES, AND DERIVATIVES. 189 20 grams benzaldehyde. 2 grams potassium cyanide. 50 cc. alcohol. 40 cc. water. Boil the mixture given above with an upright con- denser for half an hour. Cool, filter, wash with dilute alcohol, and crystallize from a little hot alcohol. A lit- tle more benzoin may be obtained by adding a little more potassium cyanide to the filtrate, and boiling again for a quarter of an hour. Yield 15 to 18 grams. Benzoin melts at 134, and boils with some decomposi- tion at 320. By warming on the water-bath for two hours with two and one- half times its weight of nitric acid (sp. gr. 1.33), with frequent shaking, it is oxidized to benzil, C 6 H B COCOC 6 H 6 . This body has been of un- usual interest, because of the part which its compounds have played in the development of the theories of stereo- chemistry. It forms two monoximes and three dioximes, to which the following stereometric formulae have been given : C.H. C CO C.H., C 6 H 6 C CO C 6 H B , I! II HO N N OH C 6 H 6 C C C e H 5 , C 8 H 6 C C C 6 H 6 , II II II II HO N N OH N OH HO N C.H.-C C-C 6 H B . II II HO N HO N Some suppose that the differences are due to struc- 1 90 ORGANIC CHEMISTRY. tural isomerism and not to stereoisomerism. See Wit- tenberg and V. Meyer: Ber. d. chem. Ges., 16, 503; Auwers and V. Meyer: Ibid, 21, 784, 3510 ; 22, 537, 564, 1985, 1996; Hantsch and Werner: Ibid, 23, n, 1243. By means of fuming hydriodic acid benzoin may be reduced to dibenzyl, C 6 H B CH 3 CH a C 6 H 6 . 74. Oxidation a of Hydrocarbon to a Quinone. An- CO thraquinone, C 6 H 4 ( )C 6 H 4 . Literature. Laurent, Berzelius : Jsb. d. chem., 16, 366; An- derson: Ann. Chem. (Liebig), 122, 301 ; Kekule", Franchimont : Ber. d. chem. Ges., 5, 908; Ullmann : Ann. Chem. (Liebig), 291, 24; W. H. Perkin, Jr.; J. Chem. Soc., 59, 1012; Graebe, Liebermann : Ann. Chem. (Liebig), Supl., 7, 285. 10 grams anthracene. 17 grams chromic anhydride. 100 cc. glacial acetic acid. Put 10 grams of anthracene, and 75 cc. glacial acetic acid in a flask connected with an upright condenser, heat to boiling, and add, slowly, 17 grams of chromic anhydride, dissolved in the smallest possible amount of water, and the solution diluted with 25 cc. glacial acetic acid. Boil for five to ten minutes, pour the solution into water, filter, and wash. Dry the residue, and crys- tallize it from glacial acetic acid, or from toluene. It may also be purified by sublimation (see p. 174). Yield almost quantitative, if the anthracene is pure. Anthraquinone sublimes in yellow needles, which melt at 273, and boil at 379-38i. 100 parts of toluene ALDEHYDES, KETONES, AND DERIVATIVES. IQI dissolve 0.19 parts at 15, and 2.56 parts at 100. By distilling with zinc dust anthracene is regenerated. 75. Preparation of Phenyl Hydrazone. Phenyl hy- r\ TT drazone of acetophenone, CH> C = N NHC 6 H 6 . Literature. B. Fischer : Ber. d. chem. Ges., 17, 573 ; 22, 90 ; 16, 2241 ; Overton: Ibid, 26, 20; Reisenegger, Ibid, 16, 661. 5 cc. acetic acid (30 per cent.). 1.5 cc. phenyl hydrazine. i cc. acetophenon. Dissolve 1.5 cc. of phenyl hydrazine in 5 cc. of acetic acid (30 per cent.) in a test-tube, add i cc. of acetophe- none, and shake vigorously till the hy drazone separates in crystalline form. Filter, wash with water, dissolve in a very small beaker, in a little hot alcohol, add water till the hot solution begins to grow turbid, and allow to crystallize. The hydrazone of acetophenone is very easily ob- tained and purified. In some cases, where there is dif- ficulty in obtaining a crystalline product, Overton (loc. tit. ) recommends to dissolve the ketone in a little glacial acetic acid, add a slight excess of phenyl hydrazine, and allow the mixture to stand in the cold till the hydrazone separates. Acetophenone phenyl hydrazone crystallizes from dilute alcohol in leaflets, which melt at 105. It is decomposed by concentrated hydrochloric acid into phenyl hydrazine hydrochloride, and acetophenone. By sodium amalgam, in alcoholic solution, it is reduced to a mixture of aniline and phenyl methyl carbinamine, C 6 H 6 CHNH 2 CH 8 ( i ' -aminoethy Iphen ) . IQ2 ORGANIC CHEMISTRY. 76. Preparation of an Oxime. A cetoxime, OTT (Isonitroso acetone or propanone oxime) . Literature. V. Meyer and Janny : Ber. d. chem. Ges., 15, 1324, 1529 ; Janny : Ibid, 16, 170 ; V. Meyer and Wege : Ann. Chem. (Liebig), 264, 121; Dodge: Ibid, 264, 185; Beckmann : Ber d. chem. Ges., ai, 767 ; Auwers : Ibid, 22, 604. 15 grams hydroxylamine hydrochloride. 14 grams (17 cc.) acetone. 8 grams sodium hydroxide. 50 cc. water. Put in a loocc. glass-stoppered bottle, 15 grams of hy- droxylamine hydrochloride, and 17 cc. of acetone, and add a solution of 8 grams of sodium hydroxide in 50 cc. of water. Shake and cool somewhat, stopper tightly, and allow to stand for twenty- four hours. Extract the solu- tion three times with about 20 cc. of ether, the ether be- ing distilled off and used again each time, because of the volatility of the acetoxime. The last time distil only about one-half of the ether, transfer the remainder of the ethereal solution to a crystallizing dish, and allow the ether to evaporate spontaneously, or better in vacua over sulphuric acid. As soon as the crystals are dry, transfer to a well stoppered bottle, as the substance is quite volatile. Yield 14 to 15 grams. In the preparation of acetoxime, it is necessary to use the sodium hydroxide and hydroxylamine in equiv- alent amounts, as the acetoxime cannot be extracted from an acid or an alkaline solution. Auwers has ALDEHYDES, KETONES, AND DERIVATIVES. 1 93 shown, however, that in some cases the formation of an oxime is facilitated by using about three times the theo- retical amount of sodium hydroxide. Acetoxime crystallizes in prisms, which melt at 59- 60. It boils at 134.8 under 728 mm. pressure. It is very easily soluble in water, alcohol, ether, and ligroin. It can be extracted with ether only from neutral, not from acid, or alkaline solutions. It is decomposed by boiling with hydrochloric acid into acetone and hydrox- ylamine hydrochloride. 77. Preparation of a Semicarbazone Compound. OTT Semicarbazone of acetone, s >C=N NH CONH a . Literature. Thiele and Stange : Ann. Chem. (Liebig), 283, 19 ; Thiele and Henser : Ibid, 288, 281, 311 ; Baeyer : Ber. d. chem. Ges., 27, 1918. 70 cc. concentrated sulphuric acid. 20 grams nitrate of urea. Ice. 20 grams nitrourea. 150 cc. concentrated hydrochloric acid. 70 grams zinc dust. Ice. Salt. 20 grams sodium acetate. 12 grams acetone. Put 70 cc. of concentrated sulphuric acid in a beaker and cool it below o with a freezing mixture. Add 20 194 ORGANIC CHEMISTRY. grams of dry urea nitrate, 1 in small portions, stirring, and taking care that the mixture does not rise above 2-3. Allow to stand for half an hour, but not after there is much evolution of gas. Pour on such a quan- tity of ice that the temperature of the mixture is about 30. Cool, filter, wash slightly, and suck as dry as pos- sible. Stir it with 150 cc. of concentrated hydrochloric acid, previously cooled to o, and containing some pieces of ice. Pour in small portions, into a mixture of 70 grams of zinc dust, with powdered ice, keeping the whole in a beaker, or, especially in working with larger quan- tities in a granite iron dish, placed in a freezing mix- ture. The temperature should be kept at about o, but the use of much ice in the solution should be avoided, because of the resulting dilution. After all has been added, allow to stand for a short time, filter, add salt to saturation, and 20 grams of sodium acetate, and filter again, if necessary. These operations should be carried through rapidly, and the solution not allowed to become warm. Add 12 grams (15 cc.) of acetone, stir thor- oughly, and allow to stand for some hours, if necessary over night, in a freezing mixture, or till the double compound of zinc with the acetone semicarbazone, =N ~ NH ~ C0 ~ NH " ZnC1 " has separated as completely as possible. Filter off, wash with a little salt solution, and a little ice- i This may be prepared as follows : Dissolve 12 grams of urea in 12 cc. of water, and pour the solution into 20 cc. of concentrated nitric acid, diluted with 20 cc. of water. Cool thoroughly, filter on a plate, and dry on filter- paper, or porcelain. 20 to 22 grams should be obtained. ALDEHYDES, KETONES, AND DERIVATIVES. 195 water. 16 to 18 grams of the compound should be ob- tained. By adding some benzaldehyde to the filtrate, stirring thoroughly, and allowing to stand, a small quantity of the semicarbazone of benzaldehyde can be obtained. To obtain the acetone semicarbazone, digest 15 grams of the salt with 30 cc. of concentrated ammonia for some time, and filter. To prepare the hydrochloride of semicarbazide, add to the acetone compound twice its weight of concentrated hydrochloric acid, and filter through a funnel loosely plugged with asbestos. Allow the solution to stand in a vacuum desiccator containing soda-lime and concen- trated sulphuric acid, till it evaporates nearly to dry- ness. Dry the crystals of the chloride on porous porce- lain. Acetone semicarbazone crystallizes in needles, which melt with decomposition at 187. It is moderately solu- ble in cold water, less soluble in alcohol, insoluble in ether. It reduces an ammoniacal alkaline silver solu- tion immediately. It is easily decomposed by mineral acids, even in the cold. The hydrochloride of semicarbazide, NH 2 CO NH NH 2 HC1, crystallizes in prisms, which melt at 173 with decomposition. It dissolves very easily in water, less easily in hydrochloric acid, and is almost insoluble in alcohol, and ether. It is decomposed by heating with acids and alkalies. It condenses readily with most ketones and aldehydes, forming usually well crystal- lized compounds. 196 ORGANIC CHEMISTRY. For the preparation of semicarbazones, Baeyer and Thiele recommend to dissolve the hydrochloride of semi- carbazide in a little water, add the calculated amount of an alcoholic solution of potassium acetate and the ketone, and then alcohol and water to complete solution. The reaction is complete in a few minutes in some cases, in others it requires 4 to 5 days. When complete, the ad- dition of water will usually cause the separation of a substance which is entirely crystalline. 78. Preparation of Furfural from a Pentose. CH CH II II CH C CHO. \X O Literature. Hill: Am. Chem. J., 3, 33 ; Stone: Ber. d. chem. Ges., 24, 3019; Am, Chem.J., 13, 73, 348; Giinther, de Chalmot and Tollens : Ber. d. chem. Ges., 23, 3575 ; Stone and Tollens : Ann. Chem. (lyiebig), 249, 227; Allen and Tollens : Ibid, 260, 291 ; Stone : J. Anal. Appl. Chem., 5, 421. ioo grams cobs of Indian corn. 500 cc. hydrochloric acid (sp. gr. 1.06). Put in a liter distilling bulb ioo grams of coarsely powdered corn cobs (or wheat straw, or wheat bran, but the yield will be smaller), and 500 cc. of hydro- chloric acid, of specific gravity 1.06 (140 cc. acid of sp. gr. i.i i, and 360 cc. of water). Fit in the mouth of the bulb a cork bearing a separatory funnel, and con- nect with a condenser. Heat to boiling, and distil slowly, at the rate of about 200 cc. in an hour, dropping in dilute hydrochloric acid (75 cc. acid sp. gr. i.n, to ALDEHYDES, KETONES, AND DERIVATIVES. 197 500 cc. of water), at such a rate as to keep the contents of the bulb constant in volume. Continue the distilla- tion for three hours, or till 600-700 cc. have distilled. Add a drop of methyl orange, and nearly neutralize the distillate with a strong solution of caustic soda; add 150 grams of salt, and distil off about 200 cc. Add 60 grams of salt to the distillate, and extract with ether. Dry the solution with calcium chloride, distil off the ether, and distil the furfural which remains. Yield 1 1 to 12 grams. Certain gums contained in the materials used are hy- drolyzed by the dilute acid, with the formation of a pen- CH a OH CHOH tose, CHOH. The pentose then condenses to furfural. CHOH CHO Furfural is a colorless oil, which boils at 161, and has a specific gravity of 1.1636 at 13.5. Its odor re- sembles that of benzaldehyde. By boiling with potas- sium cyanide, in dilute alcoholic solution, it is con- C 4 H 3 O CHOH verted into furom, , in the same manner C 4 H 3 O CO in which benzaldehyde is converted into benzoin (see 73, p. 1 88) . It condenses easily with ammonia in aqueous solution to furfuramide, (C 5 H 4 O) 3 N 2 , which is difficultly soluble. It gives a hydrazone with phenyl hydrazine, and gives a red compound with aniline acetate. Filter paper moistened with aniline acetate, furnishes a very sensitive qualitative test for furfural. IX. Sulphonic Acids and Sulphine Compounds* In the aliphatic series sulphonic acids are obtained by the oxidation of mercaptans (sulphur alcohols), with nitric acid, or with potassium permanganate. RSH + 3 O = R S0 2 .OH. They are also formed by heating the sodium salt of an acid ester of sulphuric acid with sodium sulphite in concentrated solution at a temperature of iio-i2O. (Mayer : Ber. d. chem Ges., 23, 909). R O SO 2 O lSTa+Na a SO 8 = R SO 2 ONa+Na.SO 4 . Fatty acids react with sulphur trioxide, and their an- hydrides with sulphuric acid, or with the chloride of Cl sulphuric acid SOa^' to form sulphonic acids, which contain both sulphonic and carboxyl groups, and are bibasic. The sulphonic group usually combines with the <*-carbon atom. In the aromatic series sulphonic acids are almost ex- clusively prepared by the action of sulphuric acid, sul- phur trioxide, the fuming acid, the chloride of the acid on hydrocarbons and their derivatives. The sul- phonic group usually enters into the para or ortho posi- tion with regard to NH 4 , OH, CH 3 , OR, Cl, Br, I, but in the meta position with regard to CO 2 H, SO 3 H, COH, COCH 3 , CN, CC1 3 , or NO 2 . As with nitration, homo- SUI*(, and the sulphonic acids of a- and /?-naphthylamine are especially used in the preparation of azo dyes. So. Preparation of Sulphochlorides and Sulphon- amides by the use of the Chloride of Sulphuric Acid. OTT o- and /-toluene sulphonamides, C 6 H 4 257; Brown and Blaikie : J. prakt. Chem. [2], 23, 395. 204 ORGANIC CHEMISTRY. 3 grams potassium hydroxide. 20 cc. methyl alcohol. 0.8 gram hydrogen sulphide. 13 grams methyl iodide. Put in a 200 cc. flask 3 grams of potassium hydroxide, and dissolve it in 20 cc. of methyl alcohol. Weigh on a scale sensitive to one-tenth of a gram, and pass into the solution 0.8 gram of hydrogen sulphide. Filter into a loo cc. flask, connect with an effective upright con- denser, and pour in through the latter 13 grams (5^ cc.) of methyl iodide. Warm gently till the reaction begins, and then continue to boil gently for half an hour. Pour off the warm solution from the potassium iodide which separates. On cooling, the trimethylsulphine iodide will crystallize. Pour the mother-liquors back into the flask, heat to boiling, allow to cool slightly, and pour off as before. Recrystallize the trimethylsulphine iodide once or twice from methyl alcohol. Trimethylsulphine iodide crystallizes in prisms, which are easily soluble in water, more difficulty soluble in alcohol. The study of the sulphines has established, almost beyond question, the quadri valence of the sul- phur in them. Their study has also rendered it proba- ble that the relation of the groups to the sulphur is such that no change is produced in the molecule when two of the groups exchange places, or, as usually stated, that the four valences of the sulphur atom are of equal value. X. Hydrocarbons, Hydrocarbons may be prepared by distilling salts of acids with soda-lime or barium hydroxide, or in some cases, with sodium methylate. (Mai : Ber. d. chem. Ges., 22, 2133.) RCO 2 Na + NaOH = RH + Na a CO 3 . A second method consists in treating halogen deriva- tives of the hydrocarbons with sodium, usually in ether- eal solution, or with zinc alkyl compounds. RI + R'l + 2Na = R R' + 2NaI. 2 RI + Zn = 2 R R' + Znl f . These methods are of especial value for the determina- tion of structure. A somewhat related method consists in treating a mixture of an aromatic hydrocarbon, and an alkyl chlo- ride, bromide, or iodide with dry aluminium chloride (Friedel and Crafts). This method of synthesis has already been illustrated (see 71, p. 184) , but it loses very much in value from the fact that side chains of aromatic hy- drocarbons may be removed by the action of aluminium chloride, and rearrangements are liable to result. The reaction has never been satisfactorily explained in all of its details, but it is evident that compounds containing aluminium are formed as an intermediate product. As 206 ORGANIC CHEMISTRY. an illustration of the reaction, the synthesis of triphenyl methane may be given. C 6 H 5 \ 3 C 6 H 6 + CHC1 3 + Aid, = C 6 H CH + 3 HC1 + A1C1 3 . C 6 H 6 / Alcohols are usually converted into unsaturated hydro- carbons when treated with concentrated sulphuric acid, (see 43, p. 117) or zinc chloride, or they may be converted indirectly, by the preparation from them of a halogen alkyl, and treatment of the latter with alcoholic potash. H 2 S0 4 = R"<< + H 2 0. R" + H 2 S0 4 . R< H + KOH = R " + KI + H '- In some cases quinoline may be used with advantage in place of alcoholic potash. (Baeyer: Ber. d. chem. Ges.,25, 1840, 2122.) Monohalogen derivatives of hydrocarbons may be re- duced to the hydrocarbon, the reducing agents most commonly used being concentrated hydriodic acid ; the copper zinc couple in the presence of alcohol or water (Gladstone and Tribe : Ber. d. chem. Ges., 6, 202, 454, 1136; J. Chem. Soc., 1884, 154) ; zinc in water at 150- 160 (Frankland : Ann. Chem. (L,iebig), 71, 203; 74, 41); and aluminium chloride at I2o-i5o (Kohnlein : Ber. d. chem Ges., 16, 560; Kluge : Ann. Chem. (Lie- big), 282, 214). The iodides are more suitable than other halogen derivatives for these reactions. HYDROCARBONS. 2OJ RI + HI = RH + I, 2RI + 2Zn = Zn< ^+ ZnI 2 . Zn<| + 2H 2 O = Zn(OH) a + 2 RH. Dibrom derivatives with the halogen atoms com- bined with adjacent carbon atoms, lose both bromine atoms with the formation of an unsaturated hydrocarbon on treatment with sodium, or with zinc dust and acetic acid, or with mercuric iodide, or lead iodide. Under the influence of condensing agents, such as concentrated sulphuric acid, zinc chloride, and phos- phorus pentoxide, or pentasulphide, ketones, aldehydes, and sometimes other compounds, frequently condense to form hydrocarbons. In this way mesitylene is formed from acetone, and cymene from the open chain aldehyde, geranial. (Semmler: Ber. d. chem. Ges., 23, 2965; 24, 205.) The formation of cymene from camphor is prob- ably analogous in some respects, but the mechanism of the reaction is not yet satisfactorily settled. A great variety of hydrocarbons, especially methane, defines, acetylene, and aromatic hydrocarbons, are formed by heating organic compounds to high tempera- tures. Aromatic hydrocarbons may be reduced to ' ' alicyclic ' ' compounds by reduction with hydriodic acid at high temperatures, or, sometimes, by means of amyl alcohol and sodium. Some recent work by Zelinsky indicates, however, that hydriodic acid at high temperatures some- 2O8 ORGANIC CHKMISTRY. times transforms a hexamethylene into a pentamethylene ring. (Ber. d. chem. Ges., 30, 387.) C.H.+ 6HI = C.H.. + 3I.. C 10 H 8 + 4 H = C.H..C.H.. Naphthalene. Naphthalene tetrahydride. Ketones, phenols, alcohols, and in some cases acids, may be reduced to hydrocarbons by heating with con- centrated hydriodic acid, or hydriodic acid and phos- phorus, usually in sealed tubes. 4 HI = >CH a + 2l s + H,0. Phenols, and sometimes other oxygen compounds, may be reduced to hydrocarbons by distilling over heated zinc dust, usually in a hard glass tube in a combustion furnace. The carbides of the metals, when treated with water, or with acids, give hydrocarbons which differ with the metal. Calcium carbide gives acetylene, aluminium carbide gives methane, iron carbide chiefly defines. (Moissan : Compt. Rend., 122, 1462.) Aromatic amines may be converted into hydrocarbons by treatment with nitrous acid and alcohol (see 46, p. 125) . Sometimes, however, the reaction causes the replace- ment of the ainine group by the ethoxy group, C 2 H 5 O, instead of hydrogen. (Remsen and his co-workers : Am. Chem. J., 8, 243; 9,387; IJ 3*9 J J 5 105 ; 19, 163.) HYDROCARBONS. 2OQ 82. Preparation of a Hydrocarbon by Distillation of a Salt of an Acid with Soda-Lime. Benzene, C 6 H 6 . (Phen.) Literature. Mitscherlich : Ann. Chem. (Liebig), 9, 39 ; Mar- ignac: Ibid, 42, 217; Wohler: Ibid, 51, 146; Berthelot : Ann. Chim. Phys. [4], 9, 469; Hofmann ; Ber. d. chem. Ges., 4, 163; Baeyer : Ibid, 12, 1311 ; V. Meyer: Ibid, 16, 1465. 20 grams benzoic acid. 40 grams soda-lime. Mix 20 grams of benzoic acid with 40 grams of soda lime by grinding together in a mortar. Put the mixture in a small flask, connect with a condenser, and distil over the free flame. Separate the benzene from the water, dry it with calcium chloride, and distil. If per- fectly dry benzene is desired, distil it a second time over metallic sodium. Yield 8 to 9 grams. Benzene solidifies at a low temperature, and melts at 5.42. It boils at 80.36. This method of preparation is no longer practically used, but it was of very great importance in the early study of the aromatic hydrocarbons, and illustrates a method very general in its application. 83. Preparation of a Hydrocarbon by fleans of Halogen Compounds and Sodium. Paraxylene, C.H 4 < (i-4-Dimethylphen.) Literature. Fittig, Glinzer : Ann. Chem. (Liebig), 136, 303; Jannasch : Ibid, 171, 79; V. Meyer : Ber. d. chem. Ges., 3 f 753 ; Jacobsen ; Ibid, 10, 1009, 1356; Crafts: Ztschr. anal. Chem., 32, 243; Compt. Rend., 114, mo. 210 ORGANIC CHEMISTRY. 35 grams parabromtoluene. 35 grams methyl iodide. 12 grams sodium wire. 100 cc. ether. Press into a 200 cc. flask 12 grams of sodium in the form of wire, add 100 cc. of dry ether (see n, p. 51), and place the flask in ice-water, connect with an upright condenser, and add through the latter a mixture of 35 grams of parabromtoluene, and 35 grams of methyl iodide. Allow the mixture to stand over night, or till the reaction appears to be complete. Distil off the ether on the water-bath, and distil the hydrocarbons formed over the free flame. Remove the remainder of the ether from the oil, by allowing it to stand in a crystallizing dish for half an hour in vacuo over sulphuric acid. Frac- tion repeatedly from a small distilling bulb, using test- tubes to collect the distillates, and avoiding loss, as far as possible. Collect as much as possible of the paraxy- lene, within an interval of 2 to 3 degrees. Cool this portion with ice, or in a freezing mixture, and pour off the part which does not solidify. Yield 5 to 7 grams. Paraxylene melts at 15, boils at 138, and has a spe- cific gravity of 0.880 at o. It is oxidized by dilute nitric acid to paratoluic acid, and by the chromic acid mixture to terephthalic acid. 84. Synthesis of a Hydrocarbon by Use of Aluminium C B H 6 \ Chloride. Triphenylmethane, C 6 H 5 CH. ( Friedel C 6 H B / and Crafts' reaction.) HYDROCARBONS. 211 Literature . Kekule", Franchimont : Ber. d. chetn. Ges., 5, 907 ; Bottinger : Ibid, 12, 976 : Linebarger : Am. Chem. J., 13, 557; Hemilian : Ber. d. chem. Ges., 7, 1204; Friedel, Crafts: Ann. Chim. Phys, [6], 1,489; Compt. Rend., 84, 1450; Anschiitz: Ann. Chem. (Liebig), 235, 208, 337 ; K. & O. Fischer: Ibid, 194, 352 ; Allen, Kollicker : Ibid, 227, 107 ; Biltz : Ber. d. chem. Ges., 26, 1961. 200 grams benzene. 40 grams chloroform. 20 grams aluminium chloride. Mix 200 grams of benzene with 40 grams of chloro- form, add some fused calcium chloride, and allow the mixture to stand over night. Pour off, or filter, into &dry flask, connect the latter with an upright condenser hav- ing a calcium chloride tube, which is bent downward, connected with its top. Weigh in a stoppered prepara- tion tube 20 grams of aluminium chloride, best freshly prepared. 1 Add from the tube to the mixture of chloro- form and benzene 3 to 4 grams of the aluminium chlo- ride. Shake and warm until the reaction begins ; after five to ten minutes add a second portion of the chloride, and add all of it in this manner in about thirty minutes. Boil the mixture gently for an hour, cool, pour carefully into 200 cc. of water, stir, transfer to a separatory fun- nel, shake, and separate the oil from the water, filter through a filter moistened with benzene to remove water, distil off the benzene, and collect in fractions, below 100, ioo-200, 2OO-3OO. Transfer the res- 1 Aluminium chloride may be prepared from aluminium turnings and dry hydrochloric acid gas. (Stockhausen and Gattermann ; Ber. d. chem. Ges., 25, 3521.) 212 ORGANIC CHEMISTRY. idue to a smaller distilling bulb or retort, and distil without a thermometer, or with a thermometer filled with nitrogen under pressure, till the distillate be- comes brown and viscous. Crystallize from hot ben- zene, obtaining in this way the double compound C 19 H 16 + C 6 H 6 , which crystallizes in colorless crystals, that melt at 76. The benzene can be expelled by warming the compound on the water-bath, and the tri- phenylmethane may be crystallized again from alcohol. Yield 25 to 30 grams, if the aluminium chloride is fresh. The fraction 200- 300 consists mainly of diphenyl- methane (see 87, p. 214). Triphenylmethane crystallizes in rhombic crystals, which melt at 92. It boils at 358-359. It is easily soluble in ether, chloroform, and hot alcohol, difficultly soluble in cold alcohol. If a little of the hydrocarbon is dissolved in cold fum- ing nitric acid, and the solution poured into water, trini- trotriphenylmethane is obtained. This may be reduced to the amino compound by zinc dust and glacial acetic acid. The amine may be precipitated from the filtered and diluted solution by ammonia. If the amine is heated carefully on platinum foil, with a drop of con- centrated hydrochloric acid, the red color of the chloride of pararosaniline will be noticed. 85. Preparation of a Hydrocarbon from Camphor. rTT ^CH 3 (i) Cymene, C 6 H 4 <^ < ^CH 3( - (/-Methyl-isopropyl phen.) Literature. Gerhardt and Cahours : Ann. Chem. (Liebig), 3 8 HYDROCARBONS. 213 71, 101, 205 ; Gerhardt : Ibid, 48, 234 ; Dumas, Delaland : Ibid, 38, 342; Pott: Ber. d. chem. Ges., 2, 121; Sylva : Bull. Soc.Chim., 43* 3 2 i 5 Jacobsen : Ber. d. chem. Ges., 12, 430; Widman : Ibid, 24,450; Kekule": Ibid, 6, 437; Fittica : Ann. Chem. (L,iebig), 172, 307; Naudin : Bull. Soc. Chim., 37, in. 30 grams camphor. 30 grams phosphorus pentoxide. Mix intimately in a flask 30 grams of camphor, and 30 grams of phosphorus pentoxide. Connect with a con- denser, and heat in an oil-bath as long as cymene distils. Add to the cymene a little phosphorus pentoxide, and boil a short time with an upright condenser. Pour off, and repeat a second time. Then boil the cymene with some sodium for a short time, using an upright con- denser, and finally distil. Yield 15 to 17 grams. Cymene boils at 175, and has a specific gravity of 0.8525 at 25. Potassium permanganate oxidizes it to OOTT <^*** s hydroxypropylbenzoic acid, C fl H 4 < C Q H ^ CH 9 ; the chromic acid mixture to terephthalic acid ; dilute nitric acid to paratoluic acid. 86. Preparation of a Hydrocarbon by a Pyrogenic Reaction. Diphenyl, C 6 H 5 C 6 H 6 . Literature. Fittig : Ann. Chem. (lyiebig), xax, 363; Berthe- lot: Ztschr. anal. Chem., 1866, 707: Anschiitz, Schultz : Ann. Chem. (Iviebig), 196, 48; Aronheim : Ber. d. chem. Ges., 9, 1898; Smith: Ibid, 12, 722. 200 cc. benzene. Fill the central portion of an iron tube, 2 cm. in diameter, and about 50 cm. longer than the combustion 214 ORGANIC CHEMISTRY. furnace, with broken pumice. Connect with one end of the tube, by means of a perforated cork, a tube 15 mm. in diameter, which is drawn out at one end and bent at right angles. Into the wider portion of the tube, which is bent upward, fit a cork bearing a separatory funnel in such a way that the benzene can be seen as it drops from the end of the funnel. Raise this end of the combustion furnace about two inches higher than the other. Con- nect the other end of the iron tube with a small con- denser, by means of a cork and glass tube. Drop ben- zene from the separatory funnel at the rate of about 15 drops per minute, heating the central portion of the tube to dull redness. When 200 cc. of benzene have been dropped into the tube in this manner, distil the distillate, and return to the separatory funnel the part boiling below 120. Repeat till a considerable quantity of high boil- ing products has been obtained. The benzene con- denses with evolution of hydrogen. 2 C 6 H 6 =C 6 H 6 .C 6 H 6 + 2H. Fraction the product, and crystallize from alcohol the portion boiling from 235-3OO. Diphenyl crystallizes in leaflets, which melt at 70. It boils at 254, and dissolves in 10 parts of alcohol at 20. 87. Preparation of a Hydrocarbon by the Reduction of a Ketone with Hydriodic Acid. Diphenylmethane, C 6 H 6 CH a C 8 H 6 . Literature. Graebe : Ber. d. chem. Ges., 7, 1624; Zincke, Thorner: Ber. d. chem. Ges., 10, 1473; Staedel : Ann. Chem. (Liebig), 194. 307; Zincke: Ibid, 159. 374 ; Friedcl, Crafts: HYDROCARBONS. 215 Ann. Chem. Phys. [6], i, 478; E. and O. Fischer : Ann. Chem (Liebig), 194, 253. 10 grams benzophenone. 12 grams hydriodic acid (boiling-point 127). 2.2 grams red phosphorus. Put in a tube 15 mm. in diameter, and with walls 2 mm. thick, 10 grams of benzophenone, 12 grams of hy- driodic acid (boiling-point 127), and 2.2 grams of red phosphorus. Seal carefully (see 23, p. 81), and heat for 6 hours at 160 in a bomb-oven. Open the tube care- fully by softening the capillary end in a flame till it blows out. Cut off the end of the tube, add some water and ether to dissolve the hydrocarbon. Separate the ethereal solution, filter it from the red phosphorus, distil off the ether, and distil the diphenylmethane from a small distilling bulb. Yield 8 to 8.5 grams. Diphenylmethane melts at 26-27, and boils at 263. It is easily soluble in alcohol and ether. It has a specific 26 gravity of i .0008 at 5- . 4 88. Preparation of a Hydrocarbon by Reduction with Zinc Dust. Anthracene, C 14 H 10 . Literature. Dumas, Laurent: Ann. Chem. (Liebig), 5, 10 ; Lentny : Ber. d. chem. Ges., 10, 412; xx, 1210; Berthelot : Ann. Chem. (Liebig), 142, 254 ; Behr, Dorp : Ber. d. chem. Ges., 6, 754; Perkin, Hodgkinson : J. Chem. Soc., 37, 726; Schramm : Ber. d. chem. Ges., 26, 1706 ; Jackson: Am. Chem. J., 2, 384; Anschiitz: Ann. Chem. (Liebig), 235, 165; Graebe, Liebermann : Ann. Chem. (Liebig), Supl., 7, 297 ; Baeyer : Ann. Chem. (Lie- big), 140, 295 ; Graebe and Liebermann : Ber. d. chem. Ges., i, 49; Landolt: Ztschr. Phys. Chem., 4, 369. 2l6 ORGANIC CHEMISTRY. i gram alizarin. Zinc dust. Fill a combustion tube as follows : Put near one end a loose plug of asbestos, then 5 cm. of zinc dust, then a mixture of one gram of alizarin, with 30 grams of zinc dust, then about 30 cm. of a mixture of zinc dust with about its weight of asbestos, then a plug of asbestos, loosely packed. Rap the tube on the table to give a quite free channel above the zinc dust, lay the tube in the combustion furnace, and pass hydrogen from the end first filled till the air is expelled. Heat the mixture of asbestos and zinc to bright redness, then the mixture of zinc dust and alizarin, slowly, beginning at the rear end, continuing a slow current ~>f hydrogen. Crystallize the anthracene, which sublimes to the front, cooler part of the tube, from benzene or toluene, and determine its melting-point. Also oxidize a part of it with chromic anhydride in glacial acetic acid, and determine the melting-point of the anthraquinone (see 74, p. 190). This method of preparing anthracene is of great his- torical significance, as it led Graebe and Liebermann to the discovery of the character of alizarin, and so indi- rectly led to its synthetical preparation. XL Miscellaneous Compounds* 86. Skraup's Synthesis of Quinoline. CH N CH X C CH II I H C CH CH CH Literature. Gerhardt : Ann. Chem. (Liebig), 42, 310 ; 44, 279; Baeyer : Ber. d. chem. Ges., 12, 460, 1320 ; Konigs : Ibid, 12, 453 *> X 3> 911 5 Wyschnegradsky : Ibid, 13, 911 ; Skraup, Monats- hefte, i, 317 ; 2, 141 ; J. Walter : J. prakt. Chem., 49. 549 ; Knueppel : Ber. d. chem. Ges., 29, 703 ; Marckwald: Ann. Chem. (Liebig), 279, 3. 24 grams nitrobenzene. 38 grams aniline. 100 grams concentrated sulphuric acid. 120 grams glycerol. Put in a liter flask the mixture given above, connect with an upright condenser, warm slowly till the reaction begins, remove the flame till it moderates, and then boil for two hours. Cool somewhat, add 100 cc. of water, and distil in a current of steam (see i, p. 14) as long as the dis- tillate smells of nitrobenzene. Cool, add 300 cc. of caustic soda (3 cc. = i gram), and distil over the quin- oline with a current of steam. To destroy the aniline which is present, add to the distillate 50 cc. of concen- 2l8 ORGANIC CHEMISTRY. trated hydrochloric acid, and then a strong solution of sodium nitrite, till the solution smells of nitrous acid. Heat to boiling till the diazo compound is decomposed ; add loo cc. of caustic soda, and distil the quinoline again with water vapor. Collect the quinoline with a little ether, distil off the ether, dry the residue with solid caustic potash, pour off, and distil. Yield about 40 grams. Quinoline boils at 237. It gives an orange-yellow, difficultly soluble precipitate with chloroplatinic acid, (C.H,N),H,PtCl.. The nitrobenzene used in the synthesis acts as an oxi- dizing agent, and Knueppel has shown that it may be replaced with advantage by arsenic acid. The reaction is C.H.NH. + C 3 H 8 3 + O = C 9 H 7 N + 4 H 2 O. The same reaction may be applied to a great many derivatives of benzene, naphthalene and anthracene. 90. Preparation of a Condensation Product from Phthalic Anhydride. Phenol phthalein, OH C 6 H 4 ( /0-CO c ,S C 6 H 4 / X C 6 H 4 . OH Literature. Baeyer : Ann. Chem. (Liebig), 202, 68; 183, i; Ber. d. chem. Ges., 9, 1230; Knecht : Ibid, 15, 1068; Ann. Chem. (Iviebig), 215, 83 : Menschutkin : Ber. d. chem. Ges., 16, 319: H. C. Jones and Allen: Am. Chem. J., 18, 377. 10 grams phthalic anhydride. 8 grams concentrated sulphuric acid. 20 grams phenol. MISCELLANEOUS COMPOUNDS. 2 19 Put in a small flask 10 grams of phthalic anhydride, 8 grams of concentrated sulphuric acid, and 20 grams of crystallized phenol. Heat in an oil-bath, with a ther- mometer in the mixture, at ii5-i2O for ten hours. Pour the hot mass into 100 cc. of boiling water, and boil till the odor of phenol disappears, filter hot, and wash. Dissolve the residue in a dilute solution of sodium hy- droxide, filter, precipitate with acetic acid and a few drops of hydrochloric acid, and allow to stand for twelve hours. Dry the residue, dissolve it in 6 parts of boiling alcohol, add one-half its weight of bone-black, boil for some time, filter, and wash with two parts of hot alcohol. Distil off two- thirds of the alcohol, and add a very little water. Filter, or pour off, if gummy matters separate, and precipitate the phenol phthalei'n with water, warming for a few minutes to cause it to become crystalline. The crystalline phenol phthaleiu melts at 25o-253. Phenol-phthalem forms salts with alkalies, which are soluble in water with a deep red color, owing to their dissociation, and the fact that the free ions of the acid impart to solutions a red color. Phenol phthalem itself undergoes almost no dissociation in solutions, and hence the presence of free hydrogen ions, caused by the addi- tion of an acid, even of carbonic acid, causes the disap- pearance of the color. The solutions are red in the presence of alkalies, or normal carbonates, but colorless in the presence of bicarbonates, or free acids. Owing to its extreme sensitiveness to even weak acids, phenol phthalein is especially suited as an indicator for the titration of organic acids. 22O ORGANIC CHEMISTRY. By heating with concentrated sulphuric acid at 200, phenol phthalein is converted into oxyanthraquinone, C 5 H,<>C,H,OH. If resorcin is used in place of phenol, and zinc chloride is used as a condensing agent, (half the weight of the phthalic anhydride) , the temperature being raised to till the mass becomes solid, fluorescein, OH is formed. By treating with X OH bromine in an alcoholic solution, this is converted into tetrabromfluorescem (eosin). Kosin and other similar compounds, and also anthracene derivatives which are obtained from these compounds by heating with concen- trated sulphuric acid (see above) , are used as dyestuffs. Compounds of the fluorescein type are only formed when the hydroxyl groups of the phenol are in the meta position and the third meta position is also free. 91. Preparation of a Derivative of Pyridine by Con- densation. Collidindicarboxyllic ester, CH. C 2 H 6 CO 9 C C C0 2 C 2 H & . II i C C / \^ \ CH 3 N CH 8 MISCELLANEOUS COMPOUNDS. 221 Literature. Hantsch : Ann. Chem. (Liebig), 215,8 ; Michael: Ibid, 225, 123 ; Bamberger : Ber. d. chem. Ges., 24, 1763. 20 grams acetacetic ester. 5 grams aldehyde ammonia. 10 grams diliydrocollidindicarboxyllic ester. Arsenious anhydride. Nitric acid (sp. gr. 1.30-1.33). Put in a small beaker 20 grams of acetacetic ester, and add five grams of aldehyde ammonia. Warm gently till the reaction begins, remove the flame for a short time, and then boil, with stirring, for four to five minutes in all. Add a little alcohol, and allow to cool till the dihydrocollidindicarboxyllic ester crystallizes ; filter, wash once with dilute alcohol, and then with water. A small amount of less pure ester may be obtained by diluting the filtrate. The reaction takes place in some such manner as the following : CH, C,H 6 CO 3 C IOH H|C!OH~H!CH CO 2 C 2 H 6 II : I > CH N;H a OjC / \ CH 3 CH 3 CH 3 C a H 6 CO 2 C=C CH C0 2 C,H 6 I I + 3H,0. C H 3 CH N= C CH 3 Put 10 grams of the crude ester in a small flask, add 222 ORGANIC CHEMISTRY. 20 cc.of alcohol, and pass in a rapid stream of the oxides of nitrogen, generated by warming arsenious oxide with nitric acid of sp.gr. 1.30-1. 33, passing the gases through an empty Drechsel wash-bottle to condense water. Rub- ber connections must be avoided as far as possible, be- cause the gas attacks them. Continue the passage of the gas till a drop of the solution dissolves clear in dilute hydrochloric acid. Evaporate the alcohol on the water- bath, add a strong solution of sodium carbonate, and take up the collidindicarboxyllic ester with ether. Dry the ethereal solution with ignited potassium carbonate, and distil from a small distilling bulb. Yield 7 to 8 grams. The dihydro ester crystallizes in colorless plates, which melt at 131. Its solutions show a beautiful blue fluorescence. It is almost insoluble in water, and in dilute acids, difficultly soluble in cold alcohol, easily soluble in hot alcohol, and in chloroform. It dissolves in concentrated hydrochloric or sulphuric acid. Collidindicarboxyllic diethyl ester boils at 308 310. It is easily saponified by alcoholic potash, giving a potassium salt difficultly soluble in alcohol. Collidine may be obtained from this potassium salt by mixing it with calcium hydroxide and distilling. 92. Preparation of a Pyrazolone Derivative. Anti- N-C 6 H 6 / \ pyrine,CO N CH 3 i-Phenyl-2,3-dimethyl-pyra- CH C C1I 3 zolone. MISCELLANEOUS COMPOUNDS. 223 Literature. Knorr: Ber. d. chem. Ges., 16, 2597; 17, 549, 2037; 28, 706; Ann. chem. (Liebig), 238, 137; 279, 188; 293, i ; Marckwald ; Ibid, 286, 350; Nef: Ibid, 266, 131; 287, 353; Ben- der : Ber. d. chem. Ges., 20, 2747 ; Patents, Knorr ; Ibid, 17, R, 149; Meister, Lucius, and Briining : Ibid, 18, R, 725 ; 20, R, 609 ; 27, R, 282. 13 grams acetacetic ester. 10 grams phenyl hydrazine. 10 grams i-phenyl-3-methylpyrazolone. 10 grams methyl iodide. 10 grains methyl alcohol. Putin a flask 13 grams of acetacetic ester, add 10 grams of phenyl hydrazine, and heat on the water-bath for two hours, or till a drop of the mixture becomes perfectly solid on treating with a little ether on a watch-glass. Pour the warm mass, with stirring, into a small amount of ether, filter, wash with ether, and dry. The acetacetic ester and phenyl hydrazine condense at first with the formation of a hydrazide, CH 3 \ C NH NH C 6 H & , II C 3 H B CO 2 CH and this, on heating, condenses, with loss of alcohol, to C 6 H B N / \ i-phenyl-3-methylpyrazolone, CO NH. In work- HC = C CH 3 224 ORGANIC CHEMISTRY. ing with larger amounts it may be desirable to separate the water formed by the first condensation, as Knorr suggests, but the directions given are satisfactory for small amounts. The phenylmethylpyrazolone melts at 127, is almost insoluble in cold water, ether, andligroin, more easily soluble in hot water, and very easily soluble in alcohol. It dissolves both in acids and in alkalies. Put in a thick- walled tube 10 grams of the phenyl methylpyrazolone, 10 grams of methyl iodide, and 10 grams of methyl alcohol. Seal carefully, (see 23, p. 81), and heat in a bomb-oven, or in an iron tube (to guard against explosion) in a water-bath for two to three hours. Cool, open the capillary by softening in a flame, cut off the end, transfer the contents of the tube to a beaker, add a small amount of a solution of sulphur dioxide, and some water, boil to expel the alcohol, cool, add sodium hydroxide in slight excess, and extract several times with a small amount of chloroform. Distil off the chlo- roform, and crystallize the antipyrine from toluene. The yields are nearly quantitative, except for the loss in manipulations. Antipyrine crystallizes in leaflets, which melt at 116. It is easily soluble in water, alcohol, benzene, and chlo- roform, difficultly soluble in ether and ligroin. The aqueous solution is colored red by ferric chloride. Dilute solutions give a bluish-green color with nitrous acid. CH CH II II 93. Thiophen. CH CH. \S s MISCEUvANKOUS COMPOUNDS. 225 Literature. V. Meyer: Ber. d. chem. Ges., 16, 1465, 1471; Ibid, 17, 2641 ; 18, 217 ; V. Meyer and Sandmeyer : Ibid, 16, 2176 ; Volhard and Erdmann : Ibid, 18, 454 ; Schulze : Ibid, 18, 497 ; Paal and Tafel : Ibid, 18, 456. 109 grams phosphorus trisulphide. 1 loo grams dry sodium succinate. Powder finely and mix together 100 grams of phos- phorus trisulphide, and 100 grams of sodium succinate, dried thoroughly at 140. Put the mixture in a flask or non-tubulated retort, which should be filled only half full. Connect with a condenser, which has a distilling bulb tightly fastened to its lower end and surrounded with a freezing mixture. From the side tube of the dis- tilling bulb connect tubes leading out of doors or to the chimney. Heat till the reaction begins, and then allow it to proceed of itself till completed. Distil the thiophen from the water-bath, wash it with a solution of caustic soda, dry it with sodium, and distil. Thiophen is a mobile, colorless liquid, which boils at 84'', and has a specific gravity of 1.062 at 23. On warming a minute portion of it with isatine and concen- trated sulphuric acid, a bluish-green color is produced. This reaction is used to detect thiophen in benzene. 94. Orthobenzoylbenzoic Acid, C 6 H 4 7, 220, 222 Acetaldehyde 181 Acetamide 80 Acetanilide 86, 136 Acetic anhydride 78, 58, 91 Acetic ester 87, 45 Acetone, chloroform from 119 Acetone, semicarbazone of 193 Acetonitrile 86, 81 Acetonyl acetone 53 Acetophenone, preparation, reduction 167 phenyl hydrazone of 191 Acetoxime 192, 141 ^>-Acettoluide 124 Acetyl chloride 76 derivatives 91 , 78 group, oxidation with a hypochlorite 59, 1 19, 107 tartaric ethyl ester 91 " Acid " decomposition 57, 9, 50, 55, 107 Acid sodium sulphite, compounds with ketones and alde- hydes 188, 181, 50 Acid sodium sulphite, preparation 188 Acids, derivatives of 70 amides 80, 82, 83, 227, 72 amino 97, 99 anhydrides 78, 79, 71 chlorides 76, 70 esters 87, 89, 92, 73 halogen derivatives 93, 75 inner anhydrides of bibasic 71 irnides 72 nitro derivatives 24, 95 preparation of I INDEX. 243 Acids, from alcohols 12 cyanides 32,34, 42 by condensation 44, 51, 53) 58, 59, 225 decomposition of a bibasic acid 61, 1 1 from ketones 18, 20 hydrocarbons 23, 2 natural products 63, 65, 67 qualitative characteristics of 234 separation of fatty 18, 2 Acids, uusaturated, reduction of 103, 76 Acrolein 1 76 Active forms of mandelic acid 42 Alcohol, use as a solvent 29 Alcohols, preparation 164 from aldehyde 176 halogen derivatives 166 ketones 167 preparation of hydrocarbon from 117, 206 qualitative characteristics of 237 Aldehyde ammonia 183 Aldehydes, preparation 178 from alcohol , 181 a monochlor derivative of a hydrocarbon . . 187 qualitative characteristics 238 Alicyclic hydrocarbons 207 Alizarin 172 Alkaloids, qualitative characteristics 239 Alkyl sulphonamides 85 Allocinnamic acid 59 Allyl alcohol 175, 6r dibromide 176 Allyl aniine 131 Aloxan 67 Aluminium chloride 211,184,205,206, 226 Amalgam, sodium 103 Amides 80, 82, 83, 227, 100, 4, 72 qualitative characteristics of 234 Amiue group, replacement by bromine 114, 106 cyanogen 42 hydrogen 125, 208 hydroxyl 168 the ethoxy group 208 Amines, preparation 130 from amides 99, 132, 147 cyanides 142, 132 244 INDEX. Amines, from halogen compounds 97, 144, 130 liydrazoues 132 paranitroso compounds 138, 133 oximes 140, 132 urethanes 147 separation of primary, secondary and tertiary. 85, 235 qualitative characteristics 235 Aminoacetic acid 97 Amiuoazo compounds 155, 157, 149 /-Aminoazo benzene 155, 149 0-Aminobenzoic acid 99 Aminoethanoic acid 97 i 2 -Aminoethylpheu 142 i^Aminoethylphen 144 Aminomethylphen 144 Aminonitrotoluene (4 : 2) 128, 135 Aminonitrotoluene (4 : 3) 125 2-Aminopropaue 140 />-Aminosulphobenzene 200 Ammonium acetate 80 Amyl alcohol, oxidation 12 Anaesthetic, ethyl bromide for an no Angelica lactone 69 Anhydrides of acids 78, 70, 71 Anilides 86, 73 Aniline 133 Aniline chloride 156 hydroquinone from 170 sulphonic acid of 200 ' ' Aniline yellow " 157 Anthracene 215, 190, 174 Anthranilic acid 99 Anthraquinone 190, 172, 227 Anthraquinonediol 172 Anthraquinone monosulphonic acid 173 Antifebrin 87 Antipyrine 222 Aromatic series, nitro derivatives of 25, 123, 124, 127, 128, 135, 136, 121 Arsenic, detection in ethyl bromide in tests for 231 acid in Skraup's synthesis 218 Autoclave, use for alkali fusions 174 Auxochrome groups 150 Azobenzene 154 INDEX. 245 Azo compounds and dyes 154, 155, 157, 148, 150, 201 Azoxy compounds 148 OARIUM salts of nitrobenzoic acids 30, 97 Beckmauu's mixture for oxidizing alcohols 178 rearrangement 186 Benzal acetone 60 chloride 114 Benzaldehyde 187,188,176,58, 60 Benzamide 227 Beuzene-azo-malonic ester 152 Benzene-azo-fl-naphthylamine sulphonic acid 157 Benzene, bromiuation of m condensation with benzoyl chloride 184 dipheayl from 213 nitration 123 preparation from benzoic acid 209 sulphonic acid of - 83 Benzidine 154 Benzil 189 Benzoic acid 23, 92, 209 ethyl ester 92 sulphinide 203 Benzoin 188 stereoisomerism of oximes of 189 Benzonitrile 227 Beuzophenone 184 boiling-point with varying pressures 185 reduction by hydriodic acid 215 stereoisomerism of oximes 186 Benzoquinone 170 o-Benzoy Ibenzoic acid 225 Beuzoyl chloride 92, 86, 184 derivative of a phenol 85 Benzyl acetacetic ester 55 acetone 58 alcohol 176 amine 144, 131 chloride 112, 142 oxidation of 23 cyanide 142 Bibasic acids, decomposition of 61, n ' ' Bleaching powder, ' ' preparation of chloroform with 119 Boiling-points, correction for 16, 17 Bromination 111,105,93, 75 246 INDEX. />-Brombenzoic acid 117 Brom-2-butanoic acid ' 93 -Bromtoluene 1 14, 210 Bunseu pump 48 Butane, chloriuation of 105 Butanoic acid 18, 93 3-Butanonic ethyl ester 44 i 3 -Butylouphen 58 Butyric acid 18, 93 CAD AVERIN 344 Calcium chloride, drying with 15,25,51,109, 119 combination of benzyl alcohol with 177 hypochlorite, preparation of chloroform by 119 salts 19, 37 Camphor 20, 212 Camphoraminic acids 21, 22 Camphoric acid 20 anhydride and imide 22 Camphoronic acid 22 Cane sugar, levulinic acid from 67 Carbamide > 82 Carbides, hydrocarbons from 208 Carbohydrate, levulinic acid from 67 furfural from 196 Carbon compounds, qualitative examination 23 1 Carbonyl chloride, urea from 82 Chapman filter pump 48 Chlorides of acids 76,82,83,201,227,70, 73 Chloride of sulphuric acid 201 Chlorination, direct 112, 105 of butane 105 Chlorine, preparation 112 substitution in side chain 112 tests for 231, 232, 233 Chloroform 119,107, 60 Chromic acid, oxidation with 12, 170, 182, 190, 18, 178 " Chromophor " groups 150 Cinnamic acid 58, 59, 103, 9 Ciscrotonic acid 95 INDEX. 247 Claisen distilling bulb 47 Collidine 222 Collidiuedicarboxyllic ester 220 Condensation 4 of acetic to acetacetic ester 44 acetacetic ester with a halogen compound 55, 7 acetacetic ester with itself 51 acetone with benzaldehyde 60 an aldehyde with the sodium salt of an acid 58, 9 aldehyde with itself 188 a diazo compound with amines and phenols ;':':--'' 155,157, 149 by means of aluminium chloride 184, 210, 225, 205 of ketones to hydrocarbons 212, 207 Condenser, upright or reversed 13 Copper zinc couple 228, 206' Corncobs, furfural from 196 Corrections for boiling-points and melting-points 16, 17 />-Cresol 168 Crystallization 27, 54 Cuprous bromide for Sandmeyer's reaction 1 14 Cyanhydrines 37, 3 Cyanides or nitriles 32, 35, 38, 142, 227; 2, 4, 81 amines from 142, 132 Cyclic acids 76 ketones 178 i ,4-Cyclohexanedion 55 Cymene 212 DECOMPOSITION, "acid" and " ketonic ". .. 50, 55, 57, 8 of bibasic acids 61, n Dehydracetic acid 50 Derivatives of acids 70 aldehydes and ketones.... 191, 192, 193, 178, 180 Dextrosazone 162 Diacetyl succinic ester 51 tartaric ethyl ester 89 Dialkyl sulphonamid.es 85 />-Diaminobenzene ' 136 Diazoaminobenzene 155, 149 Diazobenzene chloride 159 Diazo compounds 150 azo compounds from 155, 157, 149 cyanid es from 42, 3 248 INDEX. Diazo compounds, discussion of decomposition in Saiid- meyer's reactions 115 halogen compounds from 115, 106 hydrazine from 160 hydrocarbons from 125, 208 phenol from 168 Dibenzal acetone 60 Dibenzyl 190, 148 acetacetic ester 57 Dibromallyl alcohol 176 />-Dibrombenzene m Dibromcinnamic acid 59 Dibromethane 117 Diethyl amine 138, 133 Dihydrocollidinedicarboxyllic ester 221 Dihydroxy acids V ' * ' : l6 5 Dihydroxyquinone from a sulphonic acid 172 Diketohexamethylene 55 i, 4-Dimethylphen 209 ra-Dinitrobenzene 123 Dinitrotoluene (2:4) 135 Dioxyterephthalic acid 55 Diphenyl 213 Diphenyluiethane 214, 212 Diphenylmethanone 184 Diphenylmethanonmethyllic acid 225 Diphenylsulphone 84 Dipropylketone 18 Distillation, fractional 15 under diminished pressure 46, 48 with air condensing tube 15 steam 13,14, *9 Distilling bulb, Claisen 47 Ladenburg 47 " Division coefficient " 39 Dry ether ." : ' : 5*, 5 2 Drying under diminished pressure in distilling bulb 36 with calcium chloride 15, 25, 51, 109, 119 Dye stuffs, characteristics of 15 Dyes, azo 15. *55. 157. 2O1 * * ENOI/' form of acetacetic ester 5 Bsterification, theory of 74 Esters, amides from 7 2 preparation 87, 89, 92, 73, 80, 34 saponifi cation II INDEX. 249 Ethanol 181 Ethanediol 166 Ethanoic acid, ethyl ester of 87 anhydride 78 Ethanoyl chloride 76 Ether, purification, drying, preservation 51, 52 use in extraction 38 Ethyl aniline 138 bromide 109, 138 Ethylene 117 bromide 117,32,33, 166 cyanide 33, 144 glycol : 166 Ethyl nitrite 159, 125 zinc iodide 229 sulphuric acid, ethyl bromide from no Extraction with ether 38 F*AT, saponification of 63 Fatty acids, separation of 18, 2 sulphonic acids of 198 Ferric bromide, used in bromination in chloride, color reactions 50, 99, 103 Filtration of a hot solution for crystallization 29, 54 ^with Witt plate or Hirsch funnel 21 Fluoresce'in 220 Formaldehyde, hexamethylene amine from 145 Formic acid 61, 68, 175, n Fractional distillation 15, ,210 Friedel and Craft's reaction 184, 210, 226, 205 Furfural 196 Furfuramide 197 Furoin 197 Fusel oil, oxidation 12 Fusion of a sulphonic acid with potassium hydroxide 172 GLUCOSIDES ii Glucose 68, 162 Glucosazone 162 Glutaric acid and derivatives, anhydrides of 71 Glycerol 61, 175 Glycocoll 97 Glycollic acid 99, 167 Glycols 166, 165 250 INDEX. H AIvOGEN compounds 105 from alcohols 108, 109, 106 amines 114, 106 hydrocarbons in, 112, 117, 106 qualitative characteristics of 235 derivatives of acids 75 Halogens, tests for 231, 232, 233 Hell-Volhard-Zelinsky method for the brotnination of acids 93> 75 4-Heptanone I Hexamethylene amine 144. I3 1 compounds transformed to pentamethylene by hydriodic acid 208 Hirsch funnel 2I Hoffmann's reaction 100, 147, 99 Hydrazides T 5 2 > 223 Hydrazines.... l6o > *5i Hy drazo compounds 1 53> I 4o> I 5 Hydrazobenzene J 53 Hydrazones I 9 I > ^ l8 amines from *3 2 Hydriodic acid, reduction of ketones by 214, 208 Hydrocarbons 2 5 qualitative characteristics of 238 Hydrocinnamic acid 55> IO 3 Hydrocyanic acid, use in benzaldehyde 188 Hydrogen sulphide T 37 Hydrolysis of a pentosan 197 Hydroquinone I 7 Hydroxy acids 101,37, 7 6 acid, ester and acetyl derivative of 89 Hydroxyanthraquinone J 73 Hydroxyazo compounds 149 Hydroxybutyric acid 95 Hydroxyvaleric acid 6 9 Hydroxypropylbenzoic acid 213 Hypochlorites, use to oxidize the acetyl group 60, 119, 107 Hypobromite, use in Hoffmann's reaction 100, 147 I HIDES, qualitative characteristics of 234 Immiscible solvents 39 Indigo, anthranilic acid from IO1 Iodine, tests for 231, 232, 233 lodoso compounds 2O Isocinnamic acid 59 INDEX. 251 Isonitrosoacetone 192 Isopropyl amine 140 Isosulphocyanides 236 Isovaleric acid 12, i ICETONES 178 from chlorides of acids 184, 167 179 salts of acids 18, 178, 168 reduction of 167 " Ketonic " decomposition 50, 55, 57, 8 Knoevenagel's synthesis 10 Kohnlein's method for preparing hydrocarbons 206 Kolbe's synthesis of hydroxy acids 101, 76 " Kuppelung" 150 L ACTONE, angelica 69 valero 69 Law of division for immiscible solvents 39 4 ' I/euco ' ' compounds 150 Levulinic acid from a carbohydrate 67 Levulosazone 162 Liebermann's reaction for secondary amines 236 7VYAGNESIUM acetate, solution of 63 Malonic diethyl ester 34, 9 Mandelic acid*. 37 Manuesmann tube 174 Manometer 49 Marsh gas series, nitro derivatives of 121 Melting-points 30 correction for 16 Mesoxalic acid from aloxan 67 hydrazone of 152 Metaldehyde 184 Metanilic acid 201 Methanoic acid 61 3-Methylbutanoic acid 12 3-Methylbutanol, oxidation 17 Methyl cyanide 81 Methylene diethyl ether 146 Methyl iodide 108 /-Methylisopropylphen 212 ^-Methylphenol 168 Monochloracetic acid 34, 97 Monohalogen derivatives of the ethylene series 106, 166 " Monohydrate," sulphuric acid 96 252 INDEX. Mordants, effect on alizarin ................................ 174 " Murexid " reaction for uric acid ......................... 66 Mustard oils .............................................. 236 amine, azo compound from .................. 158 Naphthalene, nitration of ................................. 127 tetrahydride ................................ 208 Nitrate of urea ....................................... 194, 83 Nitration of acetanilide .................................... 136 acettoluide ................................... 124 benzene ....................................... 123 naphthalene .................................. 127 toluene ................................... 25, 135 toluidine ..................................... 128 urea .......................................... 194 laws of position of groups in ..................... 122 Nitric acid, oxidation with ............................. 20, 23 in tests ......................... 231 Nitriles ............................ 33, 35, 38, 43, 227, 2, 3, 81 amines from ............ . ..................... 142, 132 qualitative characteristics of ....................... 234 Nitroacetanilide, reduction ................................ 136 Nitroacettoluide (3:4) ..................................... 125 Nitrobenzene, reduction ................................... 136 o- and ^-Nitrobenzoic acid ............................. 24, 100 w-Nitrobenzoic acid ....................................... 95 Nitro compounds .......................................... 121 qualitative characteristics ................ 235 reduction ....................... 133, 135, 136 Nitrogen, tests for ............................ ....... 232, 233 #-Nitronaphthalene ....................................... 127 Nitrophthalic acid ..... .................................. 127 o- and /-Nitrotoluene ...................................... 25 ra-Nitrotoluene ........................................... 124 Nitroso compounds ................................... 139, 148 /-Nitrosodiethyl aniline .............................. 138, 133 ^-Nitrosophenol ........................................... 139 Nitrotoluidine (3:4) ........................ .............. 125 (2:4) ................................. 128, 135 Nitrourea ............................................ 194, 83 Nitrous anhydride (so-called) preparation ................. 222 OIL of bitter almonds ................................... 187 Oleic acid ................................................. 64 Osazones ......................... ................... 162, 152 Oxalic acid, decomposition of ............................. 61 INDEX. 253 Oxidation with a nitrate 187 chromic acid 12, 18, 170, 178, 181, 190 nitric acid 20, 23 potassium permanganate 24, 165 sodium hypochlorite 59 Oximes 192, 180 amines from 140, 132 0-Oxybenzoic acid 101 /-Oxybenzoic acid 103 Oxyazo compounds 149 F>ALMITIC acid 64 Paraldehyde 184 Pentamethy lene compounds from hexamethylene 208 Perkin's synthesis 58, 9 Phen 209 " Phenathylsaure " 55 i, 4-Phendiol 170 Phenethylol (i) 167 Phenethylolic acid 37 Phenmethylol 176 Phenol, benzoy 1 derivative of 86 phthalein 218 Phenols, amines from 133 from amines 168, 170, 164 sulphonic acids 172, 165 hydroxy acids from 101 qualitative characteristics of 237 Phen-3-propanoic acid 55, 103 Phenyl benzoate 86 cyanide 227 reduction 144 i-Phenyl-2, 3-dimethylpyrazolone 222 /-Phenylenediamine 136 #/-Phenylethylamine 142 Phenyl hydrazine 160, 191 hydrazone of acetophenone 191 methyl carbinamine 191 carbinol .. 167 i-Phenyl-3-methylpyrazolone 223 Phenyl propiolic acid 59 sodium carbonate 101 sulphonchloride 85 use in separating amines 85 sulphonamide 83 254 INDEX. Phosgene, urea from 82 Phosphorus oxychloride, action on acids and salts 79, 70 pentachloride " " " " " 80, 92, 70, 106 pentoxide, hydrocarbon from a ketone by 212 nitrile from amide by 227 to dry ether 52 tests for 232 trichloride, action on acids 76, 70 trisulphide, thiophen by 225 Phthalamidic acid 100 Phthalicacid 127 anhydride, anthranilic acid from 99 condensation with benzene 226 phenols 218 Pinacone from acetophenone 168 Potassium bromide 109, 114 cyanide as a condensing agent 188 permanganate, oxidation with 26, 165 test for unsaturated compounds- 104 phenolate 103 phthaliuiide, use in preparing amines 130 Primary, secondary and tertiary carboxyl, esterification of . 74 amines, separation of 85 nitro compounds, chemical character of 85 Propanoic acid 18 Propanone oxime 192 Propionic acid 18 Pyrazolone derivative 222 Pyridine derivative by condensation 220 Pyrogenic reaction, hydrocarbon by 213 QUALITATIVE examination of carbon compounds 23 1 Quinoline, Skraup's synthesis of 217 use in preparing hydrocarbons from halogen compounds 206 Quinones 171, 190, 180 REAGENTS 240 Reduction of a cyanide or nitrile 142 diazo compound 160, 151 hydrazone 132 ketone by sodium 167 hydriodic acid 214 an oxime 141 INDEX. 255 Reimer-Tiemann's reaction 76 Replacement of an amine group by bromine 114 cyanogen 42 hydrogen 125,208 hydroxyl 168 Reversed condenser 13 ' ' SACCHARINE " 203 Salicylic acid 101 Sandnieyer's reaction, discussion 115 for the preparation of a cyanide. 42, 3 bromine compound 114, 106 Sealing tubes 81 Semicarbazide 195 Semicarbazones 193, 196 181 Saponificatiou of a cyanide 32, 35, 38, 2 fat 63 Separation of the active forms of mandelic acid 42 fatty acids 18, 2 Separatory funnel 25 use in ether extractions 40 Skraup's synthesis of quinoline 217 Silver butyrate and proprionate 20 nitrate as a test for aldehydes 184, 191 Soda-lime, use to prepare a hydrocarbon 209 Sodium amalgam 76 ethy late, condensation by 44, 53, 5 hydroxide, reagent 241 hypobrotnite, use in Hofmann's reaction 100 hypochlorite, oxidation of acetyl group with 60 nitrite, reagent 241 phenolate 101 P^ss 45 pyrochroniate 12, 102 sulphite, preparation of acid 188 wire 45 Solidification of ^-cresol 170 Solvents, immiscible 39 use of 28, 29 Stannous chloride 160 Steam distillation 13 with reversed condenser 14 Stearic acid 63 Stearin 12 256 INDEX. Stilbene, formation by reduction of a nitro compound 148 Sublimation 1 74 Succinate of sodium, thiophen from 225 Succinic acid 3 2 and derivatives, anhydrides of 71 diethyl ester 89, 53 monoethyl ester 80 anhydride 79 ester 89, 53 Succinylosuccinic ester 53> 6 Sugar, leyulinic acid from 67 Sulphaminebenzoic acids 202 Sulphanilic acid 200 azo compound from 158 Sulphine compounds 203, 199 /-Sulphobenzen-azo-0-naphtylamine 1 57 Sulphonamide, phenyl 83 toluene 201 Sulphonate, sodium benzene . 83 anthroquinoiie 1 73 Sulphonchloride, phenyl 85 use of in separating amines 85 Sulphonchlorides of toluene, from chloride of sulphuric acid 201 Sulphone, diphenyl 84 Sulphonic acids I9 8 > 200, 173, 84, 172 phenols from 1 7 2 > ^5 qualitative characteristics of 238 Sulphur dioxide *7 2 Sulphuric acid, chloride of 201 " monohydrate " 96 Sulphur, tests for 231, 232, 233 TALLOW 63 Tartaric acid, diacetyl diethyl ester of 89 diethyl ester of 89 Terephthalic acid from cymene 213 toluic acid 44 />-xylene 210 Tetrabromfluorescein 220 Tetraldehyde l8 4 Thermometers, testing and correction of io Thiocarbamic acids, derivatives of 236 Thiophen from sodium succinate 224 Toluene, ^-brom IJ 4 INDEX. 257 chlorination in side chain 112 nitration of 25, 135 m-nitro 124 sulphonamides and sulphonchlorides of 201 /-Toluic acid from cytnene 213 toltiidine 42 /-xylene 210 /-Toluidine, ^-acettoluide from 1 24 />-cresol from 168 nitration of 128 />-toluic acid from 42 ^-tolunitrile from 42 Trichlormethane 119 Trimethylene cyanide, reduction of 144 Trimethyl sulphine iodide. 203 Trinitrotriphenylmethane 212 Triphenylmethane 210 Tubes, sealing of 8r UNSATURATED acids, reduction of 103, 76 alcohol 1 75 Upright condenser 23 Urea 82 formation from aloxan 67 nitrate 194, 83 nitro 194 use in preparing a phenol 169 Urethanes, use in preparing amines 147 Uric acid 65 VALERIC acid, iso 12 hydroxy 69 Valerolactone 69 Volatile liquids, preservation of 52, 109 Vinyl bromide 119, 166 1A7 ASHING soluble substances 21 Witt plate 21 />-J?Cylene, preparation 209 ZINC alkyl compounds, hydrocarbons from 205 chloride as a condensing agent 133, 220 copper couple 206, 228 dust, reduction by distillation with 215 ethyl '^^^^!^^L 228 OTHER PUBLICATIONS. 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