PRACTICAL ORGANIC CHEMISTRY BY JULIUS B. COHEN, PH.D., B.SC. PROFESSOR OF ORGANIC CHEMISTRY, THE UNIVERSITY, LEEDS AND ASSOCIATE OF THE OWENS COLLEGE MACMILLAN AND CO., LIMITED ST. MARTIN'S STREET, LONDON RICHARD CLAY AUD SONS, LIMITED., BREAD STREET HILL, E.C, AND BUNGAY, SUFFOLK. First Edition, 1900. Reprinted 1904, 1907. Second Edition^ 1908, 1910. PREFACE TO THE FIRST EDITION THE present volume is an enlarged edition of that published in 1887, and has been completely rewritten. The preparations have all been carefully revised, some of the former ones omitted and many new ones introduced. The chief additions are the introductory chapters on organic analysis and molecular weight determinations, and an extension of the appendix. The book does not aim at being a complete laboratory guide, but is intended to provide a systematic course of practical in- struction, illustrating a great variety of reactions and processes with a very moderate outlay in materials and apparatus. The objection may be raised that the detailed description of processes makes no demand upon a student's resourcefulness or ingenuity. It must be remembered, however, that the manipulative part of organic chemistry is so unfamiliar to the elementary student that he requires minute directions in order to avoid waste of time and material. Until he..has acquired considerable practical skill he cannot accomplish the experi- mental work requisite for research, and repeated failures will be apt to destroy his confidence in himself. To satisfy, to a.legitimate extent, the prejudices of certain examining bodies, who still adhere to the old system of testing a student's knowledge of practical organic chemistry by means of the qualitative analysis of certain meaningless mixtures, the special tests for some of the more common organic substances have been inserted. At the same time, an attempt has been at the end of the appendix to systematise the analysis of PREFACE TO THE FIRST EDITION organic substances on a broader and therefore more rational basis. The present occasion seems opportune to direct attention to the fact that one of the most familiar, most readily procurable and most cheaply produced of all organic materials is placed beyond the reach of many students by the heavy duty levied upon it. May I, in the name of teachers of organic chemistry, appeal to the Board of Inland Revenue, on behalf of scientific and technical education, to provide institutions for higher education in science with a limited quantity of pure alcohol free of duty, thereby placing schools of chemistry in this country in the same position as those on the Continent ? In conclusion I desire to thank Dr. J. McCrae, who has written the section on Ethyl Tartrate and the use of the Polari- meter, Dr. T. S. Patterson, who has been kind enough to look •over the proofs, and Mr. H. D. Dakin, who has given me sub- stantial assistance in the practical work of revision. J. B. COHEN. THE YORKSHIRE COLLEGE, October; 1900. PREFACE TO THE SECOND EDITION IN the former edition attention was drawn to certain drawbacks which accompanied the study of practical organic chemistry, among which the heavy duty on alcohol and the unsatisfactory nature of the practical tests demanded by public examining bodies were specially emphasised. Teachers and students alike must welcome the changes which have since taken place. An excise duty on alcohol used in the laboratory is no longer exacted from students of science, and substantial reforms have been introduced into practical examina- tions. One important feature in some of the new examination regulations is the recognition of the candidate's signed record of laboratory work. We are, in fact, beginning to discover an inherent .defect in practical chemistry as an examination sub- ject, namely, its resistance to compression into a compact and convenient examination form. The old and drastic method by which chemistry was made to fit into a syllabus consisted in cutting out the core of the subject, or in other words, in removing all the processes which demanded time, skill, and some intelligence, and in reducing the examination to a set of exercises in a kind of legerdemain. This process has been to a large extent abandoned, but a residuum of it s.till remains. It is to be hoped that the kind of practical examination in organic chemistry, which consists in allotting a few hours to the identification of a substance selected from a particular list, will in time be superseded or accompanied by a scheme encouraging candidates to show, in addition to tfceir note-books, evidence of skill and originality, as, for viii PREFACE TO THE SECOND EDITION example, in submitting specimens of new or rare preparations, or in presenting an account of some small investigation. The present edition is much enlarged and contains new pre- parations, reactions and quantitative methods, all of which have been carefully revised. My object has been not to follow any particular syllabus, but to present a variety of processes from which a selection may be made to suit the special needs of different students. My thanks are due to Mr. Joseph Marshall, B.Sc, and several of my senior students, for their assistance in the work of revision. J. B. COHEN THE UNIVERSITY, LEEDS. July, 1908. CONTENTS ORGANIC ANALYSIS— PAGE Qualitative examination i Carbon and Hydrogen I Nitrogen 2 The Halogens 3 Sulphur 3 Phosphorus 3 Quantitative estimation 4 Carbon and Hydrogen 4 Nitrogen 13 The Halogens , 22 Sulphur 28 Determination of molecular weight 28 Vapour density method 29 Cryoscopic or Freezing-point method 32 Ebullioscopic or Boiling-point method 37 Molecular weight of acids 43 Molecular weight of bases 46 PREPARATIONS— General remarks 47 Purification of spirit 48 Ethyl alcohol ; 49 Potassium ethyl sulphate . 50 Crystallisation . 52 Ethyl bromide 54 CONTENTS PREPARATIONS— PACE Dehydration of liquids 56 Determination of specific gravity 56 ,, boiling-point 58 Ether 59 Purification of commercial ether 61 Ethylene bromide 62 Acetaldehyde 64 Methyl alcohol 67 Methyl iodide 68 Amyl alcohol 69 Amyl nitrite 69 Acetone , . 69 Chloroform 70 Acetoxime 71 Melting-point determination 72 Acetic acid 74 Acetyl chloride 74 Acetic anhydride ...... 76 Acetamide 77 Heating under pressure . 78 Acetonitnle 79 Methylamine hydrochloride (Hofmann's reaction) ... 80 Ethyl acetate . 81 Ethyl acetoacetate $3 Distillation in vacuo 84 Monochloracetic acid 87 Monobromacetic acid 89 Glycocoll 90 Glycocoll ester hydrochloride 92 Preparation of hydrogen chloride 93 Diazoacetic ester 94 Diethyl malonate . 96 Ethyl malonic acid 97 Chloral hydrate 99 Trichloracetic acid , 99 Oxalic acid . * $00 CONTENTS PREPARATIONS— rAGE Methyl oxalate 101 Glyoxylic and Glycollic acids 102 Palmitic acid 104 Glycerol 106 Formic acid 106 Distillation in steam 107 Allyl alcohol 109 Isopropyl iodide no Epichlorhydrin in Malic acid 112 Succinic acid 113 Tartaric acid 114 Ethyl tartrate 115 Determination of rotatory power 116 Racemic and Mesotartaric acid . 122 Resolution of Racemic acid (Pasteurs method) ... 123 Pyruvic acid 124 Citric acid 124 Citraconic and Mesaconic acid 125 Urea 126 Thiocarbamide 128 Uric acid 128 Alloxantin 129 Alloxan 130 Caffeine [31 Creatine 132 Tyrosinc and Leucine (E. Fischer's ester method) ... 133 Grape sugar 135 Benzene 136 Purification of Benzene 136 Fractional distillation 136 Bromobenzene 14° Ethyl benzene 141 Nitrobenzene T42 Azoxybenzene r43 Electrolytic reduction of Nitrobenzene 144 CONTENTS PREPARATIONS— I«AC;E Azobenzene *45 Electrolytic reduction of Nitrobenzene 145 Hydrazobenzene 146 Benzidine 14S Phenylhydroxylamine 148 Nitrosobenzene 149 j^-Aminophenol . 149 Aniline 149 Acetanilide 151 ^-Bromacetanilide 152 /-Nitraniline 155 7//-D initrobenzene 154 7/z-Nitraniline 154 ;/z-Phenylenediamine 155 Dtmethylaniline 156 /-Nitrosodimethylaniline 157 Thiocarbanilide 159 Phenyl thiocarbimide 160 Triphenylguanidine 160 Diazobenzene sulphate 161 Toluene from/-toluidine 163 /-Cresol 164 /-Chlorotoluene 165 ^-Chlorobenzoic acid 166 /-Bromotoluene 167 /-Iodotoluene 16S Tolyliodochloride 169 Iodosotoluene 169 p -Tolylcyanide 159 STli acid jyo jyo Terephthalic acid 1yl Diazoaminobenzene 1yl Aminoazobenzene iy2 Phenylhydrazine ly^ Phenyl methyl pyrazolone (Knorr's reaction) .... 175 Sulphaniltc acid x^- CONTENTS PREPARATIONS— PAGE Methyl orange • . 176 Potassium benzene sulphonate 177 Benzenesulphonic chloride • 178 Benzene sulphonamide 179 Phenol 179 Anisole 181 Hexahydrophenol (Sabatier and Senderens5 reaction) . 181 •0- and jz^-Nitrophenol l$3 Picric acid 185 Phenolphthalein V^!86 Fluorescein and Eosin 187 Salicylaldehyde and ^-Hydroxybenzaldehyde (Reimer's reaction) • 188 Salicylic acid (Kolbe's reaction) 190 Quinone and Quinol 192 Benzyl chloride 194. Benzyl alcohol 195 Benzaldehyde 196 a- and /3-Benzaldoximes 197 Benzoic acid 199 Nitro-, Amino-, and Hydroxy-benzoic acid ...... 200 w-Bromobenzoic acid 201 Benzoin 202 B'enzil 203 Benzilic acid 203 Cinnamic acid (Perkin's reaction) 204 Hydrocinnamic acid • 204 Mandelic acid 205 Phenyl methyl carbinol (Grignard's reaction) 206 Benzoyl chloride 208 - Benzamide 209 Ethyl benzoate 209 Quantitative hydrolysis of ethyl benzoate 210 Acetophenone (Friedel-Crafts3 reaction) 210 Acetophenoneoxime 211 Acetophenonesemicarbazone 212 jjv o >NTI:\ r> PREPARATIONS - Beckmann's reaction Benzoylacetone (Claisen's re.t< !i<>;i ... Diphenylmethane . Triphenyl methane Malachite green Naphthalene . Phthalic acid 5-Naphthalencsulphonate of sodium /3-NaphthoI Estimation of methoxyl (ZeiscP> mcthn.i} . „ ,, acetoxyl