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Practical organic chemistry (1920) by Julius Berend Cohen - PDF ebook

Practical organic chemistry 

Practical organic chemistry
Practical organic chemistry (


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 especially emphasized. 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 examinations.

 One important feature in some of the new examination regulations is the rec6gnition 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 subject, 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 still 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consists in allotting a few hours to the identification of a substance selected from a particular list, will in time be superseded or accompanied by a scheme encouraging candidates to show, in addition to their note-books, evidence of skill and originality, as, for example, in submitting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 preparations, 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.


Some contents of the book:

ORGANIC ANALYSIS 
Qualitative examination I
Carbon and Hydrogen I
Nitrogen 2
The Halogens 3
Sulfur 3
Phosphorus 3
Quantitative estimation 4
Carbon and Hydrogen 4
Nitrogen 13
The Halogens 22
Sulfur 28
Determination of molecular weight 28
Vapour density method 29
Cryoscopic or Freezing-point method 32
Ebullioscopic or boiling-point method 37
The molecular weight of acids 43
The molecular weight of bases 46
PREPARATIONS
General remarks 47
Purification of spirit 48
Ethyl alcohol 49
Potassium ethyl sulfate. 50
Crystallization 52
Ethyl bromide 54
PREPARATIONS PAGE
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
Acetonitrile 79
Methylamine hydrochloride (Hofmann's reaction) ... 80
Ethyl acetate 81
Ethyl acetoacetate 83
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 .... 100


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