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OSMANU UNIVERSITY LIBRARY 

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LABORATORY MANUAL 
of ORGANIC CHEMISTRY 



BY 



HARRY L. FlgHER, Ph.D. 

Instructor in Organic Chemistry, Columbia University 



FIRST EDITION 



NEW YORK 

JOHN WILEY & SONS, INC. 

LONDON: CHAPMAN & HALL, LIMITED 
1920 



1RAUNWOHTH * CO, 
BOOK MANUPAOTURIM 
CLYN. (I. V. 



PREFACE 



THIS book is the outgrowth of almost ten years of intensive 
laboratory teaching. Practically all the laboratory experi- 
ments, in mimeograph form, have been in the hands of three 
different classes tff students, day, night, and summer, each year 
for over five years, and dXiring this time have been repeatedly 
corrected. As our classes grew we found it necessary to keep 
to a definite list of experiments and all our attention was devoted 
to these. In order to bridge the gap between the particular reac- 
tion studied and allied reactions, many questions were added. 
These questions have been made the basis of laboratory quizzing 
and are meant primarily for the student to use for his own ad- 
vancement in the subject to aid him to become his own teacher. 
A portion of the questions are on the practical work in the 
laboratory, that is, on the methods of handling apparatus, etc. 
Many of them will appear to be perfectly obvious. They are; 
nevertheless, put in since it has been noticed that it is the most 
obvious point which is most often overlooked. 

The experiments are, in general, the usual ones found in 
laboratory manuals, changed of course in accordance with our 
experience, and they were chosen for their teaching value and 
for the good all-round practical manipulation involved. There 
are only a few innovations. Menthone and menthone oxime 
illustrate typical reactions even though their formulas may seem 
large to the beginner. Glycocoll is prepared by hydrolysis, 
thus linking up the chemistry of the proteins with that of 
simpler compounds. Limonene dihydrochloride has tremendous 
teaching value, and the synthesis of camphor from pinene gives 
an opportunity for select work in an enticing field. The methods 
described give good yields in most cases, but the yield was 
not the prime reason for choosing any experiment. 

It will be noticed that there are no directions for preparing 



IV PREFACE 

such substances as acetacetic ester, malonic ester, etc. These 
can advantageously be given in connection with special advanced 
synthetic work, for example, malonic ester can be prepared as 
the starting-point in the synthesis of veronal (barbital), acet- 
acetic ester and also phenyl hydrazine in the preparation of 
antipyrine, anthraniiic acid for methyl anthranilate or indigo, 
ethylene chlorhydrin for novocaine (procaine), pyruvic acid 
for atophan, etc. 

In the large classes of to-day the beginning student does not 
any longer have the opportunity of " rubbing elbows " with the 
older men and learning from such contact many of the little 
things about laboratory manipulation which aid materially in the 
successful outcome of an experiment. For this reason, the 
first experiments in this book are written up in considerable detail 
with the hope that after the student has learned how to set up 
his apparatus in the correct way, he will thereafter follow this 
practice. For the most part this hope has been realized in this 
laboratory. All operations are described where they are first 
used, in the order of the experiments, and afterwards their use 
only is mentioned, sometimes being cross-referenced, but always 
fully indexed. Special discussions are included only where it is 
believed the material cannot be found in the ordinary books which 
the student has at his disposal. 

It is assumed that before beginning organic laboratory 
work students have been prepared with a long course in general 
chemistry and a short course in qualitative analysis. 

A shortened organic course is mentioned below which has been 
designed especially for pre-medical students. A good grounding 
in organic chemistry is, however, absolutely essential for the 
study of medicine, and the long course should be taken whenever 
possible. A student gets much more out of his work when he 
prepares certain compounds and has time to study their char- 
acteristics and think over his work, than when he goes through a 
very great number of test-tube reactions which superficially are 
very much alike and therefore the more easily forgotten. 

The long course consists of two afternoons a week for two 
semesters, and Comprises for the first semester, experiments 



PREFACE V 

Nos. 1-7, 9-15, 17-23, and for the second semester, experiments 
Nos. 24-29 (i), 30-46, 48-49? 5 x -53' 5 6 > S 8 , 6 5> 66. These are 
arranged in the order of discussion found in Stoddard's " Intro- 
duction to Organic Chemistry." The short course consists of 
two afternoons for one semester, and comprises experiments 
Nos. i, 2, 3, 4, 28, 5, 10, 6, 24, 12, 25, 29 (i), 16, 19, 22, 30, 8, 9, 
26, 27, 34, 37, 33, 38, 43. 45> 46, 5 X > S3* 49, 13 (optional), in the 
order given. This different order is in accordance with the 
discussion in Moore's " Outlines of Organic Chemistry." Since 
the order of both courses is not the same, some of the experiments 
in the long course which also occur early in the short course, 
have been written up in greater detail than would ordinarily 
be necessary from their position in the list. A list of apparatus 
furnished to each student and lists of the chemicals used in each 
course will be found on pages 312-323. In our laboratory each 
student receives his complete set of chemicals and apparatus 
for the semester when he starts work, and keeps them in his desk. 

Each desk in the organic laboratory at Columbia University 
is equipped with gas (2), air blast, water (2 outlets including one 
which can be used for suction pump), steam cup, steam outlet 
for steam distillation, etc., draft pipe (downward), and electric 
fixture for extra light and with a 2o-ampere connection. It 
is expected that in addition a special hot-plate will soon be 
installed having a steam pipe cast in it and also having another 
pipe cast in it which can be connected with the air blast to 
give hot air when desired. At the adjacent sink is a goose-neck 
outlet for water and another one with a steam mixer attached 
for producing water of any desired temperature. The desks, 
phich are 6 feet long, contain the Fales type of cupboards, and 
are arranged for two students to work on alternate afternoons. 
There are no shelves or racks between the desks and on this 
account the room is light and it is possible to look across the entire 
laboratory at any time. The room is of course equipped with 
fire extinguishers, bottles of dry sodium bicarbonate for burning 
oil, and blankets, at each end of every aisle, and three needle 
shower-baths in case one's clothing catches fire. 

A book is never a thing by itself. It is always a growth and 



vi PREFACE 

many factors and influences from other workers contribute 
largely in the making of it. The author is very glad to make 
acknowledgment for assistance of various kinds to such works 
as the following: Barnett, " The Preparation of Organic Com- 
pounds"; J. B. Cohen, " Practical Methods of Organic Chem- 
istry"; E. Fischer, " Introduction to the Preparation of Organic 
Compounds"; Gattermann, "Practical Methods of Organic 
Chemistry"; Henle, " Anleitung fur das organisch praparative 
Praktikum"; Holleman, " Laboratory Manual of Organic 
Chemistry for Beginners "; L. W. Jones, " Laboratory Outline 
of Organic Chemistry"; F. J. Moore, " Experiments in Organic 
Chemistry "; J. F. Norris, " Experimental Organic Chemistry "; 
W. A. Noyes, " Organic Chemistry for the Laboratory "; Sud- 
borough and James, " Practical Organic Chemistry "; and Ull- 
mann, " Organisch-chemisches Praktikum." Special references 
are given here and there largely to induce students to get ac- 
quainted with articles in the journal literature and thus to 
stimulate them toward acquiring a good scientific attitude toward 
chemistry. 

I wish to make most generous acknowledgment to my friend 
and colleague, Professor John M. Nelson. The work herein set 
forth was begun with him and grew under his constant sympa- 
thetic support and kindly guidance. His sound advice and 
valuable suggestions call for my most cordial thanks. 

I am also indebted to Professor Thos. B. Freas and his asso- 
ciates of the stock room for many favors and to Mr. S. J. Ballard, 
who made many of the drawings and prepared all for the pub- 
lishers. My sincere thanks are also given to Dr. George 
Scatchard and Mr. William E. Morgan, and to many students 
whose friendly advice and helpful co-operation has been of the 
greatest assistance. 

A special foreword concerning organic combustions which 
constitutes the subject of the second part of this work will be 
found just preceding that part. 

HARRY L. FISHER 

COLUMBIA UNIVERSITY, 
June, 1919. 



CONTENTS 



PART I 
LABORATORY EXPERIMENTS 

EXPf. NO. PAGE 

GENERAL NOTES AND SUGGESTIONS i 

IN CASE OF ACCIDENT OR FIRE 6 

*i. DETERMINATION OF THE BOILING-POINT AND STANDARDIZA- 
TION OF THE THERMOMETER IN THE ORDINARY DISTILLA- 
TION APPARATUS 7 

*2. FRACTIONAL DISTILLATION; FRACTIONATION OF A MIXTURE 

OF ETHYL ALCOHOL AND WATER 22 

*3. ABSOLUTE ALCOHOL 26 

*4. TESTS FOR CARBON AND HYDROGEN IN ORGANIC COMPOUNDS 30 
*5. METHANE FROM CHLOROFORM AND CHEMICAL PROPERTIES 

OF PARAFFIN HYDROCARBONS 31 

*6. PREPARATION OF ETHYL IODIDE FROM ETHYL ALCOHOL. ... 35 

7. PREPARATION OF ETHYLENE AND ETHYLENE DIBROMIDE. . 40 

*8. ETHYLENE 48 

*9. ACETYLENE 

(i.) From Calcium Carbide 50 

(2.) From Ethylene Dibromide 52 

*io. ALCOHOLS, REACTIONS OF 54 

ii. THE IDENTIFICATION OF AN ALCOHOL THE METHYL 

ESTER OF 3.5-DiNiTROBENZOic ACID 55 

*i2. DETERMINATION OF THE MELTING-POINT 58 

*i3. PREPARATION OF DIMETHYL-ETHYL-CARBINOL (Grignard's 

Reaction) 69 

14. PREPARATION OF METHYL-PHENYL-CARBINOL 73 

15. DISTILLATION in vacuo OR UNDER DIMINISHED PRESSURE. . 76 

* These experiments constitute the short course, see p. v. 
vii 



viii CONTENTS 

EXPT. NO. PAGE 

*l6. ACETALDEHYDE (Solution) 83 

17. PREPARATION OF ACETALDEIIYDE AMMONIA 85 

18. ACETALDEIIYDE FROM ALDEHYDE AMMONIA 90 

*i9. TESTS FOR ALDEHYDES 91 

20. METHYLAL. HYDROLYSIS OF METIIYLENE DIETHERS 94 

21. FORMALDEHYDE: TEST FOR FORMALDEHYDE, AND PREPA- 

RATION OF HEXAMETHYLENETETRAMINE 96 

*22. ACETONE 98 

23. PREPARATION OF /-MENTHONE AND /-MENTHONE OXIME. . . 99 

*24. PREPARATION OF ACETYL CHLORIDE 102 

*25. PREPARATION OF ETHYL ACETATE 106 

*26. HYDROLYSIS (VSAPONIFICATION) OF BUTTER 108 

*2y. LECITHIN FROM EGG-YOLK no 

*28. DETECTION OF NITROGEN, SULFUR, THE HALOGENS, AND 

PHOSPHORUS IN AN ORGANIC COMPOUND 112 

*2Q. PREPARATION OF ACETAMIDE 

(1) From Ammonium Acetate and Glacial Acetic Acid. . 115 

(2) From Ammonium Acetate in a Sealed Tube 117 

*3o. METHYL AMINE 1 20 

31. ETHYL ISOCYANATE 122 

32. METHYL MUSTARD On 123 

*33. PREPARATION OF GLYCOCOLL FROM HIPPURIC ACID. PURI- 
FICATION OF AN AMINO ACID 124 

*34. HYDROLYSIS OF SUCROSE (CANE SUGAR) AND PREPARATION 

OF PlIENYLGLUCOSAZONE 127 

35. PENTOSES. FURFURAL TEST 132 

36. PREPARATION OF Mucic ACID 134 

*37. CELLULOSE ACETATE 137 

*38. BENZENE: CHEMICAL PROPERTIES 138 

39. PREPARATION OF ETHYL BENZENE (Fittig's Reaction) .... 141 

40. PREPARATION OF DIPIIENYLMETHANE (Friedel-Crafts' Re- 

action) 144 

41. TRIPHENYLMETIIYL 147 

42. PREPARATION OF BROMBENZENE 149 

*43. PREPARATION OF BENZENE SULFONIC ACID, SODIUM SALT. . 152 

44. PREPARATION OF NITROBENZENE 154 

*45. PREPARATION OF ANILINE 157 

*46. PREPARATION OF ACET-^-TOLUIDIDE 164 

47. PREPARATION OF SULFANILIC ACID 167 



CONTENTS ix 

EXPT. NO. PAGE 

48. BENZIDINE REARRANGEMENT 169 

*49. DYES: PREPARATION OF METHYL ORANGE 170 

PHENOLPHTHALEIN 171 

FLUORESCEIN 171 

CRYSTAL VIOLET 171 

50. PREPARATION OF CRYSTAL VIOLET 175 

*5i. PREPARATION OF PHENOL, AND .REACTIONS OF PHENOLS. . . 177 

jj2. ,PRF;PARATION OF ANISOLE 180 

53. BENZALDEHYDE 182 

54. PREPARATION OF HYDROCINNAMIC ACID 184 

55. PREPARATION OF />-TOLUNITRILE 187 

56. PREPARATION OF ACETANTHRANILIC ACID 189 

57. PREPARATION OF METHYL SALICYLATE 191 

58. TANNIN 193 

59. PREPARATION OF LIMONFNE DIHYDROCIILORIDK 195 

60. CAMPHOR SYNTHESIS: PINENE HYDROCHLORIDE 198 

61. CAMPIIENE 202 

62. ISOBORNYL ACETATE 205 

63. ISOBORNEOL 206 

64. CAMPHOR 208 

65. PREPARATION OF ANTHRAQUINONE 210 

66. PYRIDINE AND QUINOLINE 213 

PART II 
ORGANIC COMBUSTIONS 

DIVISION A 
The Determination of Carbon and Hydrogen 

PAGE 

I. HISTORICAL INTRODUCTION 217 

II. LIST OF APPARATUS AND CHEMICALS 223 

III. TOPICAL OUTLINE OF GENERAL METHOD OF PROCEDURE. . 224 

IV. THE APPARATUS AND How TO PUT IT TOGETHER, WITH 

NOTES ON MANIPULATION 225 

The apparatus is arranged in the following order and 
is discussed in this same order: 

i. Tank of Compressed Oxygen with Stand and Pressure 
Gauges 225 



X CONTENTS 

PAGE 

2. Bubble Counter 227 

3. Gas Purifying Apparatus, including the Pre-heater. ... 228 

4. a. The Electric Combustion Furnace 230 

b. The Combustion Tube and How to Fill It 231 

5. Absorption Train 236 

a. First Absorption Bottle : for Water 238 

b. Second Absorption Bottle : for Carbon Dioxide 243 

c. Guard Tube and Bottle of Palladious Chloride 
Solution 245 

V. METHOD OF RUNNING BLANK DETERMINATIONS 246 

VI. WEIGHING THE ABSORPTION BOTTLES 248 

VII. WEIGHING THE SUBSTANCE 250 

VIII. THE COMBUSTION PROPER 253 

IX. CALCULATIONS, AND DISCUSSION OF RESULTS 257 

X. SOME COMMON ERRORS AND How TO AVOID THEM 261 

XI. COMBUSTION OF SUBSTANCES CONTAINING NITROGEN, 

SULFUR, HALOGENS, PHOSPHORUS, SODIUM, ETC 265 

XII. COMBUSTION OF LIQUIDS, GASES, AND EXPLOSIVE SUB- 
STANCES 267 

DIVISION B 
The Determination of Nitrogen 

I. HISTORICAL INTRODUCTION 269 

II. LIST OF APPARATUS AND CHEMICALS 271 

III. TOPICAL OUTLINE OF GENERAL METHOD OF PROCEDURE. . 273 

IV. THE APPARATUS AND How TO PUT IT TOGETHER, WITH 

NOTES ON MANIPULATION 275 

1. The Carbon Dioxide Generator 275 

2. The Manometer, accompanying Stop-cocks, U-tube, 

etc. ..". 281 

3. The Electric Combustion Furnace 283 

4. The Combustion Tube and How to Fill It 284 

5. The Azotometer (Nitrometer) 285 

V. THE FINAL PREPARATION OF THE CUPRIC OXIDE 288 

VI. WEIGHING THE SUBSTANCE 292 

VII. THE COMBUSTION PROPER 293 

VIII. CALCULATIONS, AND DISCUSSION OF RESULTS 300 

TABLES FOR NITROGEN 303 

TABLE OF LOGARITHMS 308 



PART I 

LABORATORY EXPERIMENTS 



LABORATORY MANUAL OF ORGANIC 
CHEMISTRY 



GENERAL NOTES AND SUGGESTIONS 

Each preparation, if a liquid, is placed in a square 15 cc. 
glass-stoppered bottle, 1 and, if a solid, in a 20 cc. round wide- 
mouthed bottle, 1 and neatly labeled with the name of the 
substance, the corrected boiling-point or melting-point, as found 
by you, the yield of pure substance (always in grams, to the 
first decimal place, as originally obtained even though some 
material may have been used for special experiments), and the 
name of the student, for example: 

Ethylene dibromide 

B. P. 131 cor. 

Yield, 20.2 grams 

JOHN SMITH 

The yield is the amount of pure product actually obtained. 
The "theoretical yield" is the amount which would be obtained 
if the reaction went entirely to the right according to the ordi- 
nary equation, in other words, if the starting material was 
entirely converted into the product desired. 

The yield given in the experiments is the amount usually 
obtained by following out the directions carefully. It is not 
the theoretical yield. 

1 Practically all the preparations will give amounts that will be contained by 
bottles of these sizes. Acetaldehyde ammonia and acet-o-toluidide will be found 
too bulky, but it is expected that only a sample of these will be handed in for 
inspection, the remainder being used for preparing another substance. 



2 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Only through the intimate acquaintance made in the labor- 
atory in the actual handling and the preparation and purifica- 
tion of compounds can the student hope to gain a thorough, 
comprehensive knowledge of the properties and reactions of 
organic substances. Study the experiments first with the aid 
of the text-book and afterwards carry them out in the laboratory. 
Always read through the entire experiment before beginning any 
work in the laboratory. It is most important THAT YOU KNOW 

WHAT YOU ARE DOING WHEN YOU ARE DOING IT. 

Wherever possible save time by looking ahead and working 
on more than one experiment at a time. 

Neatness will be insisted upon in all laboratory work. Set 
up your apparatus neatly and in good shape, and do not allow 
unnecessary and unused apparatus to collect around it. Keep 
the desk top free from dirt and oil spots. The apparatus in 
the cupboards of the desks should be clean and neatly arranged. 
The desks will be inspected by the instructor periodically. 

All apparatus and chemicals must be placed within the 
desk at the end of each laboratory period. Whenever it is 
necessary to leave apparatus on the desk a "red tag" permit 
will be issued by the instructor. In such cases do not leave 
out burners, or any other disconnected pieces of apparatus. 

Grades. The laboratory grade will be based upon (i) 
the quality and yield of preparations, and (2) the general man- 
ner in which the student performs his laboratory work, includ- 
ing his manipulation, neatness, knowledge of the experiment 
while the work is being done as evidenced by replies to oral 
questions, etc. This second part is given several times the weight 
of the first. 

Note-books. It is recommended that each student keep 
a note-book. Two pages should ordinarily be allowed for each 
experiment: the left-hand page for the Type of Reaction, the 
Object of the Experiment (for example, the Preparation of 
Ethylene dibromide from Ethylene and Bromine), the Equa- 
tion for the Reaction, Materials to be used, any special notes, 
and references; and the right-hand page for the Method of 
Preparation, B.P. or M.P. of Substance as found, Yield, Theo- 



GENERAL NOTES AND SUGGESTIONS 3 

retical Yield and Percentage Yield, which is the actual yield 
multiplied by 100 and divided by the theoretical yield, Chemical 
and Physical Properties, Notes, and any other data. The topics 
for the left-hand page given above refer particularly to the 
"preparations." For other experiments use special topics as 
needed. Make the Method of Preparation or Procedure con- 
cise: do not rewrite the directions as given in the laboratory 
directions. Use constitutional formulas throughout. The 
left-hand page should be written up before the apparatus is 
assembled and the experiment started. The right-hand page 
should be written up immediately after the experiment is com- 
pleted. Be brief. 

Amounts of Chemicals. In every case carefully weigh or 
measure out all chemicals, regardless of what amount may be 
stated on the label. If a horn-pan balance is used for weigh- 
ing, place papers in the scoops. Sometimes the exact amount 
is not necessary, as in the methane experiment. Although the 
laboratory work in organic chemistry is not carried out with 
the same degree of accuracy, as for example in quantitative 
analysis, the best results are obtained only when molecular 
quantities are used, and these are usually given in the direc- 
tions. Chemicals should generally be weighed to the first 
decimal place. 

For a liquid, the specific gravity equals the weight divided 
by the volume. This simple expression should always be borne 
in mind when making calculations where liquids are involved. 

Cutting Sticks of Solid Sodium or Potassium Hydroxide. 
Caustic alkali should not be handled with the fingers. Put 
the stick on a piece of filter paper, and turn up one side as a 
buffer. A common knife and a 'sharp blow upon it will quickly 
cut off the desired amount. Protect the eyes with goggles. 
For alkali in the eye, use castor oil. (See p. 6.) 

Rubber Stoppers should not be left in any piece of apparatus 
which has been heated. They should be removed, if possible, 
as soon as the heating is discontinued. Otherwise the stopper 
will be molded to the shape of the opening by the contraction 
of the glass in cooling. 



4 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Loosening Ground Glass Stoppers and Stop-cocks. The 

following is very often efficient in loosening glass stoppers and 
stop-cocks. Give a stout piece of twine one or two turns around 
the neck of the bottle and heat the glass by drawing the string 
rapidly back and forth. 

In case this method does not work, compare opening of 
bromine bottles, Note 3, p. 33. 

An excellent method of removing "frozen" stop-cocks is 
given by V. C. Allison (Journ. Ind. and Eng. Ckem., 11 (1919), 
468). The handle of the key is slipped into a socket in a block 
of hard wood while the opening of the block rests as a collar 
on the shoulder of the barrel of the stop-cock. A plug of wood 
is placed against the other end of the key, and easy regular 
pressure brought to bear by means of a vise. Different sizes 
are given for the ordinary stop-cocks in use. The scheme is 
rapid and it works! 

Following are the names of three concise and valuable handy 
books 'which contain a large amount of chemical data in com- 
pact ready-reference form: 

Van Nostrand's "Chemical Annual," 8vo; " Chemiker- 
Kalender" (German), 2 vols., i2mo; "Handbook of Chemistry 
and Physics," 7th Ed., 1919, published by The Chemical Rubber 
Co., Cleveland, O., i2mo. 

Collection of Liquid Specimens in the " Preparations." 
In the Boiling-point Experiment (Experiment No. i) you will 
observe the influence of radiation, superheating, etc., and this 
will give you an idea as to how even pure liquids behave during 
distillation in the ordinary apparatus. When you are making 
pure specimens the behavior of these pure liquids should be 
kept in mind. There will be a small portion passing over within 
2-3 before the temperature has reached the proper boiling- 
point, and another small portion near the end as the temperature 
rises 2 or 3. Usually in ordinary laboratory "preparation" 
work thes first and last runnings are collected along with the 
major portion distilling at a constant temperature and the 
entire amount weighed as a specimen. Material boiling below 
or above these limits should be discarded. On the label state 



GENERAL NOTES AND SUGGESTIONS 5 

the range of temperature in which the material was collected 
and also give the corrected boiling-point where the temperature 
remained constant for a long interval. 

Sodium Residues. Great care should be exercised in handling 
residues of sodium. It should not be put into the sink or the 
waste jar, but should always be destroyed by adding it in small 
pieces to some alcohol or acetone in a beaker, waiting until 
practically all action has ceased with each piece before adding 
another. Then very carefully pour the solution into the sink. 
Also rinse the flask with alcohol or acetone before adding any 
water. 

In the laboratory directions which follow, very detailed 
directions are given at first. Later, when the general manipula- 
tion should be well understood all the details arc not given. 
Then the experience gained in the earlier part of the course 
should be properly used when necessary. 

The organic laboratory is open during definite hours on 
the regular days and it is expected that students will do all 
their work during these specified times. 

Plan your work and work your plan! 

You can more readily show your interest in organic labora- 
tory work by carrying it out according to well-studied plans 
than by dilly-dallying along at all hours and wasting your time 
and the time of others also! 

Don't leave the gas, water, blast or steam turned on for any 
reason whatsoever when you leave the laboratory. 

Don't make any unnecessary noise in the laboratory. (Please 
note especially in the use of the air blast.) 

Don't forget that you will not get any more out of your work 
than you put into it! 



In Case of ACCIDENT or FIRE 

FIRE. Fire extinguishers are hung up all around the room. 
In case of burning oil use the powdered sodium bicarbonate 
in the bottles on the racks. 

The blankets are for wrapping round a person whose cloth- 
ing is on fire. If necessary, use the needle showers. 

ACCIDENT. On the special shelf in the laboratory are: 
Boric acid solution, saturated, for the eyes. 
(Eye-cups hang below shelf.) 

Acetic acid, 1 per cent solution, for washing alkali from 
the skin. 

Carron oil (half linseed oil and half lime water), for all 
kinds of burns, including alkali and acid burns on skin. 
Shake well before using. 

Castor oil for eye burns, especially alkali in the eye. 
There is a first aid kit in the instructor's laboratory. 

ACIDS. On skin: wash with much water immediately, then 
with dilute sodium bicarbonate. Use carron oil (on shelf) ; 
on clothing: wash with dilute ammonium hydroxide 
solution. 

ALKALIES. In the eye: use saturated boric acid on shelf if 
injury is slight. Drop castor oil into the eye; on skin: wash 
with much water, then with dilute acetic acid, i per cent 
solution, or saturated boric acid solution. Use carron oil; 
on clothing: use some weak acid like acetic or boric, wash, 
and then neutralize any remaining acid with ammonium 
hydroxide or ammonium carbonate. 

BROMINE. On skin: wash with any solvent, like alcohol, 
benzene, gasolene, benzine, carbon tetrachloride, or dilute 
sodium bicarbonate. Then treat with carron oil or car- 
bolated vaseline. 

NOTE. Post a copy of this sheet on the bulletin board and also 
give the name and telephone number of the nearest physician and 
the nearest hospital. 

6 



Experiment No. 1 1 

Determination of the Boiling-point and Standardization of the 
Thermometer in the Ordinary Distilling Apparatus 

One of the characteristic physical constants of a liquid is 
its boiling-point, and a compound is generally considered pure 
when it distills at a constant boiling-point, under constant pres- 
sure. It may also aid in the identification of a compound. 
In regular laboratory work it is determined by means of a ther- 
mometer in a distilling flask and the temperature of the vapor 
entering the outlet tube is recorded as the boiling-point of the 
liquid. Obviously in this method, when the ordinary long-scale 
360 thermometer is used, there are several errors, of which 
the following are most important: the true boiling-point is not 
usually found because the entire column of mercury is not sur- 
rounded by the vapor, the vapor is easily superheated, and 
the thermometer may be inaccurate. Since the boiling-point 
of each liquid compound prepared in the course must be deter- 
mined with a fair amount of accuracy, the thermometer must 
be standardized at the beginning, and in order that any cor- 
rection found may apply in the regular work the same general 
form of apparatus will be used in the standardization as in the 
regular work. 

The error due to the cooling of the column of mercury which 
extends above the stopper of the flask, and therefore out of the 
vapor of the boiling liquid, often amounts to 6 or 7 for high- 
boiling liquids. It can be corrected as described in the notes 
at the end of the experiment, but the method of correction is 
open to grave errors, since it is seldom possible and not always 
convenient to obtain the required average temperature of the 

^ave you read over the section entitled "General Notes and Suggestions"? 
p. i. 

7 



8 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

exposed mercury column. Furthermore this correction varies 
and must be made every time a distillation is carried out. This 
so-called "stem correction" can be obviated by using a ther- 
mometer with a short scale and of such a size that the entire 
column of mercury will be surrounded by the vapors of the 
boiling liquid. In order that the ordinary range of boiling- 
points of common liquids may be covered you will use a set 
of three thermometers 1 each one of which has a short scale 
with a total range of 120, No. i, 15 to 135; No. 2, 95 to 
215; No. 3, 175 to 295. (See Fig. i.) These thermometers 
"over-lap" each other by 40, and this makes it possible to choose 
the one which can be employed to the best advantage. Pure 
liquids will be used in the tests and a comparison experiment 
will be made in at least one instance to show the extent of the 
stem correction by using both a short-scale and a long-scale 
thermometer 2 with the same liquid (aniline). 

The error due to superheating can be made a minimum by 
proper heating of the liquid in the flask. 

The temperature which is obtained under conditions where 
the errors mentioned above have been eliminated or reduced 
to a fraction less than the error of observation is generally 
considered as the corrected boiling-point. Such a temperature 
when written is followed by the abbreviation "cor." This dis- 
tinguishes it from the multitude of unqualified (meaning gener- 
ally uncorrected) boiling-points which unfortunately fill the 
literature and text-books. More corrected boiling-points are 
now being reported than ever before, and this is a good omen 
for future work. It is hoped that henceforth an unqualified 
boiling-point will mean a corrected boiling-point. 3 If the cor- 

1 The markings on solid stem thermometers often become very dim and dif- 
ficult to read on account of the loss of the blackening from the fine lines. This 
can be remedied by rubbing a little graphite over the lines and wiping off the 
excess. 

2 A method of standardizing a long-scale thermometer is described in the 
notes, p. 20. 

3 Even this book contains some boiling-points which are unqualified, since it 
has not always been possible to find the data in the literature or to obtain the 
pure materials, etc., necessary. 



-Outside diameter 5 to 5% mm. 

(o) 



1 

7T J 



-735 



-75 



-275 



-95 



-295" 



-175 



FIG. i. Short Scale Thermometers. 

Manufactured by Eimer & Amend, N. Y., and sold under the name of Fisher Organic 

Thermometers. 

9 



10 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

reeled boiling-point is for a pressure other than 760 mm., the 
pressure is placed as a subscript before the temperature, for 
example, "b.p. 735 99 cor." 

Set up a distilling apparatus, using a 60 cc. distilling-flask, 
style B (Fig. 2), and a condenser 1 with straight inner tube. 
Clamp the flask securely, but not too tightly, above the outlet 
tube (why?) and if possible just under the lip. (Why?) 
Select the thermometer which has the right temperature on 
the scale where it will be surrounded by the vapor of the liquid 
(water, in the first distillation) and fasten it in the neck of the 
flask with a sound well-bored cork. Fasten the outlet tube in 
the larger end of the condenser. The outlet tube should pass 
far enough into the condenser that the vapors will be delivered 
directly into the part of the condenser that is surrounded by 
the water. (Why?). Compare upper sketch in Fig. 3. 

The bulb of the thermometer should be placed just Mow 
the outlet tube, but not in the bulb of the flask, and never in 
the liquid. (Why?) It must not touch the walls of the tube. 
(Why?) Be sure that the cork does not cover up the thermometer 
where the degrees must be seen. In this event raise or lower 
the thermometer, or cut off a complete portion of the cork or 
exchange the flask. When the short-scale thermometers are 
used this difficulty will seldom be encountered. 

Soften the selected cork by means of a cork press. (There 
are cork presses on the side walls of the laboratory.) Or wrap 
it in a filter paper and roll it under foot. Make a hole with a 
sharp cork-borer which has a slightly smaller diameter than the 
desired opening. Hold the cork in the hand and turn the borer 
gently by means of the rod, which should be inserted through the 
holes in one end of the borer. In order to bore the hole straight 
it is often found convenient to keep turning the cork in the 
left hand after each slight twist of the borer, and not take the 
right hand from the handle of the borer at all. If the cork is 
placed on the desk, the borer under excessive pressure gouges 
out the inside of the cork and in addition plunges through to 

x When the word "condenser" is used it ordinarily means a condenser with 
water jacket (Liebig condenser). 



LABORATORY EXPERIMENTS 



STYLE- A 

High CM//*?/- for Low 
Boiling Liquids 



11 



STYLE: - 

Low Qit+t&i- /of- High 
Boiling 




ORDINARY 
DISTILLING FLASKS 




DISTILLING FLASKS 



12 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

the hard surface of the stone covering, and its cutting edge is 
ruined. As a rule it is well to pull out the borer when it is half 
through the cork, and push out the cork plug inside before con- 
tinuing the boring. In this way a clean, even cut is made 
throughout. Use a rat- tail file to enlarge the opening and make 
it fit tightly. Place the cork on the desk and run the file back and 
forth, always pressing downwards and meanwhile rolling the 
cork. The cork should slide over the tube with only moderate 
pressure. Never try to thrust a tube through a cork of too small 
aperture; an injured finger or hand is very inconvenient, if 
not useless, for laboratory work. Take hold of the tube near 
the cork and twist it slowly as it is carefully forced in. It is 
advisable to use new corks as much as possible in organic work, 
and therefore a good supply of the different sizes should always 
be kept on hand. 

Always remove the stopper from a flask or condenser before 
changing the position of any glass tube or thermometer in the 
hole of the stopper. 

Set the condenser at a convenient angle so that the condensed 
liquid will drop directly into the receiver, which should, as a 
rule, rest upon the desk. Use a large condenser clamp, 1 with 
the two prongs underneath, and turn the heavy base of the stand 
toward you where it will be underneath the condenser. The 
base of the stand to which the distilling-flask is attached should 
also be underneath the flask and turned toward you. It is not 
always necessary that the distilling-flask be absolutely vertical. 
The positions of the flask and the condenser can conveniently 
be arranged before connecting any parts of the apparatus by 
putting them in place with the upper part of the condenser in 
line with, but just behind, the outlet tube of the flask. Then 
when the apparatus has been adjusted for the proper angles, 
the condenser can be slid down through the large clamp and 
then brought up around the outlet tube of the distilling-flask 
and fastened. 

In case it is desired to disconnect the distilling-flask with- 

1 The prongs of all clamps should be protected with white rubber tubing 
or strips of cork or felt. 



LABORATORY EXPERIMENTS 



13 




f 

Ordinary Distillation Apparatus 

With Liebig straight water condenser and Ertenmeyer 
f/crsk as receiver 

V 




wifh ^Jdd/1-ion-f-ube 
and ref/ux (but bed) wafer 
condenser attached 



Flask 

Condenser connected 

with a bent tube 



Calcium Chloride 
Tube 



FIG. 3. 



14 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

out changing the clamps and adjustments, it is easier to do this 
by loosening the stopper in the upper part of the condenser 
and allowing the condenser to slide down through the large 
clamp before removing the distilling-flask, rather than to dis- 
arrange the setting of the clamps and stands by taking away 
the distilling-flask first. After the distilling-flask is ready, with 
fittings made, etc., and clamped in the original position, the 
condenser can then readily be replaced and connected without 
changing the angle and main position of any clamp. 

The upper outlet for water from the condenser should be 
above the jacket so as to give the maximum condensing sur- 
face since the condenser will then be full of water. It should 
be somewhat slanted so that the rubber tube which carries the 
waste water will not kink. The rubber tubes slip on easily if 
a drop of water is used as a lubricant or if moistened by means 
of the breath. 

Use a small Erlenmeyer flask as the receiver. 1 

Add 15 cc. of distilled water to the distilling-flask, using 
a funnel whose stem reaches below the opening of the outlet 
tube, and drop in several small pieces, not dust particles, of 
porous tile to prevent bumping. Heat the flask directly 2 with 
a small blue flame 3 not over i cm. in height, giving it a rotary 
motion at first, and hold the burner obliquely so that in case 
the flask breaks the hand will not be in danger. When the 
liquid distills regularly the burner should be set directly under- 
neath and with the flame touching the flask. Do not heat the 
surface above the liquid as this will superheat the vapors. Avoid 
drafts; use a conical metal shield chimney for the burner or a 
large wind shield for the apparatus. 

The temperature will rise rapidly at first until near the 

1 Such a receiver should never be fastened to the condenser by means of a 
stopper. (Why?) 

2 When a larger flask is used, as in some of the later experiments, it is pro- 
tected with a wire gauze when being heated. This method, however, generally 
tends to superheat the vapor and therefore gives high results in distillations. 

8 Such a small flame can easily be obtained by cutting down the supply of 
air at the same time that the gas supply is lowered. Always regulate the gas sup- 
ply (of the Tirrill burner) by means of the set screw at the base. 



LABORATORY EXPERIMENTS 15 

boiling-point of the substance, and then slowly until finally 
it will remain practically constant. Distill over at least one-half 
of the liquid. 1 The constant temperature within one-half of 
one degree at which most, if not all, of it distills is noted as the 
observed boiling-point. Toward the end of the distillation the 
temperature may rise slightly on account of superheating. 
Record the corrected barometer 2 reading also. 

NOTE : The salient points in connection with carrying out a 
distillation are a stable and well set-up apparatus, with receiver 
resting upon the desk, the thermometer properly placed, corks 
well bored, and a small-sized flame used in the right way to prevent 
superheating. 

Next, carry out another distillation, using the same amount 
of pure aniline, 184.4 cor -> under the same general conditions, 
except that the water condenser is replaced with an "air" con- 
denser 3 and a style C distilling-flask (Fig. 2) is used instead of 
style B. A water condenser with no water in it should not be 
used in place of the "air" condenser because of the danger of 
cracking at the joints. A flask with a low outlet tube is used 
for high-boiling liquids in order to avoid too much condensation 
and on this account excessive heating which causes a partial 
decomposition of the substance. The distilling-flask and con- 
denser must be clean and dry, and fresh porous tiling should be 
used as before. 

In order to dry a piece of apparatus rapidly, rinse it with 
alcohol and then with ether (keep all flames away). To remove 
the ether vapors connect a glass tube leading almost to the 
bottom of the flask with the suction or the blast. Since the air 
from the blast is likely to be contaminated with iron dust, 

1 The effect of superheating upon the temperature of the boiling-point can be 
seen if all the liquid is distilled over. There is practically no danger of cracking 
the flask if it is made of Pyrex glass. 

2 For correcting the barometer reading see p. 300. 

3 An air condenser is a long, straight, thin glass tube of 1.0-1.5 cm. diameter. 
The inner tube of a Liebig water condenser makes a very convenient air con- 
denser (see Fig. 3). It is used when the substance boils above about 150-160. 
If a substance solidifies readily it would clog the condenser, and is therefore 
collected directly from the end of the outlet tube. Compare Expt. No. 51, phenol. 



16 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

oil, moisture, etc., it is better to use the suction. The wash 
alcohol and ether can be used again, and should be placed in 
bottles properly labeled and kept for this purpose. Acetone 
may be used instead of the alcohol-ether combination. 

The substance distilled may have absorbed a little moisture 
in the handling, etc. This will be evidenced by a turbidity in 
the first runnings. 1 

Repeat the distillation with pure aniline, but this time use an 
ordinary long-scale 360 thermometer instead of the short-scale 
thermometer. Compare the temperature obtained in each case. 

Since the boiling-point varies with the air pressure a correction 
must be applied unless the barometer shows 760 mm. For 
non-associated liquids, the correction 2 for a difference of every 
10 mm. in pressure, in the vicinity of 760 mm., may be found 
by dividing the absolute temperature of the boiling-point by 
850, that is, 

Corrected observed b.-p. = temp. of obs. b.-p.+ 

273+temp. of obs. b.-p. 760 cor, barometric reading^ 





For associated liquids, such as alcohols, acids, and hydroxyl 
compounds generally, divide by 1020, instead of 850. Water 
is an associated liquid, and aniline is a non-associated liquid. 

For a more complete standardization, two temperatures, 
one near the bottom and one somewhat near the top of the 
scale of each of the three thermometers, should be checked 
up. The following combinations of liquids, all of which are 
found in the list given below, can be used: For thermometer 
No. i, chloroform and water; for No. 2, water and aniline; 
and for No. 3, aniline and quinoline. 

The following is a list 3 of liquids which when pure are suit- 
able for testing the accuracy of thermometers at the corrected 
temperatures for 760 mm. given: 

1 Regarding the absorption of moisture by pure liquids when handled in ordi- 
nary operations, compare Young and Fortey, Trans. Chem. Soc., 83 (1903), 65. 

2 Alex. Smith and Menzies, Journ. Amer. Chem. Soc., 32 (1910), 907. 

3 Compare Young, " Fractional Distillation," 10. 



LABORATORY EXPERIMENTS 17 

Carbon bisulfide 1 46 . o 

Chloroform 61.3 

Benzene 80. 2 

Water 2 100.0 

Ethylene dibromide 131.2 

Chlorbenzene 131 . 95 

Brombenzene 3 155 . 5 

Aniline 184 . 4 

Nitrobenzene 210.9 

Naphthalene 218.0 

Quinoline 237 . 5 

a-Bromaphthalene 280.4 

Benzophenone 305 . 9 

Mercury 356 . 8 



NOTES ON BOILING-POINT AND DISTILLATION 

i. The boiling-point of a liquid is that temperature at which 
the saturated vapor pressure of the liquid becomes equal to the external 
pressure, and usually this external pressure is the atmospheric pres- 
sure. 

"The true boiling-point of a liquid is identical with the condens- 
ing-point of its vapor under the same pressure, provided that some 
liquid is present and that the vapor is not mixed with an indifferent 
gas or vapor, and it is generally more convenient to measure the 
condcnsing-point of the vapor than the boiling-point of the liquid. 
To do this an ordinary distillation bulb is generally employed." 
Young: "Fractional Distillation," p. 26. 

"The correct boiling-point of a liquid at atmospheric pressure is 
best determined by wrapping cotton-wool, or, if the liquid attacks 
that substance, asbestos, round the bulb of the thermometer. By 

1 Carbon bisulfide is very inflammable and great care must be exercised in hand- 
ling and distilling it. A bath of warm water can be used for heating it, but the 
vapor should not be superheated. 

2 Water is the only associated liquid in this list. 

3 Considerable difficulty has been encountered recently in obtaining bromben- 
zene of the desired purity. That on the market is probably all prepared by direct 
bromination of benzene which was not properly purified. Preparation on a 
small scale from pure aniline by Sandmeyer's reaction is recommended. 



18 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

this plan, even though the vapor may be superheated, yet the liquid 
in contact with the thermometer bulb must be at the true boiling- 
point, since it has a free surface of evaporation." Ramsay and 
Young, Trans. Chem. Soc., 47, (1885), 42. Compare Cottrell, 
"On the Determination of Boiling-points of Solutions," Journ. 
Amer. Chem. Soc., 41 (1919), 721-9; and Washburn and Read, "The 
Laws of 'Concentrated' Solutions, VI, The General Boiling-point 
Law," ibid., 41 (1919), 729-41. Figures of a special apparatus are 
given in both articles. 

For the determination of correct boiling-points a special form of 
apparatus is used in which all possible errors from superheating, 
radiation, etc., are provided against. Short-scale thermometers 
which are made of normal glass and which have been properly stand- 
ardized are employed. Normal glass is a special glass that has been 
aged by suitable treatment of heating, etc., until its behavior on 
further heating and cooling has become uniform. Such thermometers 
can be obtained with certificates showing the results of standardization 
by certain bureaus of different governments, like the U. S. Bureau 
of Standards. 

2. A liquid ought to boil as soon as its vapor pressure becomes 
slightly greater than atmospheric, but it is a well-known fact that 
boiling does not necessarily take place under these conditions. Most 
liquids can readily be superheated. 1 The transformation of a liquid 
into the vapor phase will, however, take place immediately if the 
vapor phase any inert gas be introduced, but not otherwise.- 
For comparison we have the supercooling of a liquid which will solidify 
as soon as a particle of the solid phase is added, for example, ice 
in supercooled water. 

Superheating cannot take place at the surface of a liquid since 
there the liquid is always in contact with the vapor phase. It always 
takes place in the interior and especially at the bottom where the 
heat is applied. It is of course not possible to go an unlimited dis- 
tance into the metastable "area," since the further away we get 

1 It is of interest to note that chloroform, which ordinarily boils at 61, has been 
heated to a temperature of 100 by suspending the drops in a zinc chloride solu- 
tion of the same specific gravity, and that water has similarly been heated to 170 
by suspending it in a mixture of oils. (Dufour, Arch, dc la Bibl. univ. (1861) 
T. XII, 210; and Pogf*cndorfs Annalen, 124 (1865), 205.) 

2 Aitken, "On boiling, condensing, freezing, and melting," Trans. Royal Scot- 
tish Society of Arts, 9 (1875), 240-87; Duhem, "Thermodynamics and Chem- 
istry," trans, by Burgess, (1913), 365-8. 



LABORATORY EXPERIMENTS 19 

from equilibrium the greater is the tendency for the system to come 
to equilibrium. Finally this tendency will become so great that the 
system will be able to overcome its reluctance to a change of phase, 
vaporization will then take place suddenly and sometimes with great 
violence in other words, bumping occurs. Stirring 1 helps to prevent 
bumping, since the liquid is thus evenly heated and vaporization 
will take place readily at the surface, as mentioned above. The 
best means to prevent bumping is to introduce the vapor phase 
directly, and this is done in several ways, (i) By passing a stream of 
air bubbles through a capillary tube into the liquid (see Expt. No. 15, 
Vacuum Distillation). (2) Another method which is very convenient 
for a short period is to place in the liquid a small glass tube, about 
i mm. in diameter and sealed at one end. It should be long enough 
to stand upright, and when in position the open end should be at the 
bottom. On warming the liquid the air in the tube expands and 
bubbles through the liquid. If the distillation is interrupted, a 
new tube must be introduced. (3) By using pieces of porous tiling 
which contains a large amount of air. Pumice cannot be used so 
well, since it floats in most liquids and therefore does not introduce 
the air bubbles at the seat of the trouble. Glass beads, and many 
substances with "points" are often used to prevent bumping, but 
their efficiency does not' depend upon their "points," but upon the 
air which is adsorbed on their surfaces. As soon as this air has been 
driven off they are no longer of any use, unless they are removed, 
dried and heated before being used again. 2 Even platinum "tri- 
angles" after a time must be removed, heated, and allowed to cool 
in the air before being introduced again. 3 Fine particles of any sub- 

1 Morgan, "The Elements of Physical Chemistry," 5th Ed., (1914), 178. 

2 Ostwald-Luther, " Physiko-chcmische Messungen," 3. Auilage, (1910) 219; 
Lehmann, " Molekularphysik," (1889), II, 151. 

3 E. C. Kendall, in a recent note, Journ. Amer. Chem. Soc., 41 (1919), 1189, 
states that carbon in certain forms is an excellent aid to produce rapid boiling. 
"It was found, however, that the various forms of carbon differ greatly in their 
power to cause rapid boiling of a solution. While powdered charcoal or coke has 
slight power in this respec , anthracite coal is without exception the very best 
substance to bring about the rapid boiling of a solution. The formation of bub- 
bles does not take place on the sharp edges and corners alone, but over the hard, 
smooth surfaces of the coal minute bubbles form with great rapidity, and under 
some conditions a piece of coal 2 cm. cube can be raised from the bottom of the 
flask by the rapid formation of bubbles on its surface. It acts in a similar man- 
ner in the acidification of a carbonate or sulfite solution If the coal is 

kept under water indefinitely it becomes less active, but heating in an oven will 



20 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

stance rapidly lose their adsorbed air and then they increase the 
tendency to bumping instead of decreasing it. 1 

3. The "stem correction," in degrees= +N(t 00.000154, 
where A^=that portion of the mercury column which is not heated 

by the vapors, read in degrees; 
/= observed boiling temperature; 

t' average temperature of the exposed column of mercury 
as found by a second thermometer hung beside the first 
one; 
0.000154= coefficient of apparent expansion of mercury in glass. 

4. Standardization of a long-scale thermometer. 

A long-scale thermometer is standardized by locating certain 
points found by means of the boiling-points of pure liquids such as 
those on p. 17, and also the freezing-point of water, and then by 
plotting these results on co-ordinate paper the correction for any 
one degree may be read off at any time. The correction is of course 
larger as the boiling-point increases, and often amounts to several 
degrees for higher-boiling liquids. The results are applicable only 
for the particular distilling flasks used in obtaining the data. 

On a piece of cross-section millimeter paper, 100X300 mm., 
mark on the lowest heavy horizontal line as the abscissa the degrees 
of the thermometer every 50, counting each millimeter as a degree. 
The corrections are generally to be added, and are therefore plotted 
above the main line. If any minus corrections are found, the heavy 
horizontal line chosen must, of course, be far enough above the bot- 
tom of the sheet to allow space for the proper corrections. The 
amount of the correction, that is, the difference between the "cor- 
rected observed reading" and the true boiling-point at 760 mm., 
is plotted on a perpendicular line as an ordinate, opposite the num- 
ber on the abscissa corresponding to the "corrected observed read- 
ing," and counting each centimeter as a degree. Connect the four 
points thus found with a smooth curved line. From this curve it 
is now possible to tell at a glance the correction for any degree as 
follows: add to the corrected observed reading the difference in 
degrees between the main abscissa at the point of the corrected 
observed reading and the point where its ordinate cuts the curve. 

restore its activity. . . . One or two pieces of about i cm. cube are better than 
many smaller pieces.'* 

1 1 am indebted to a "seminar" paper on " Bumping" by Mr. Harold L. Simons 
for most of the material presented in Note 2. 



LABORATORY EXPERIMENTS 21 

Put all the data used in the plotting in a convenient corner of the 
same paper for reference. 

The curve between 155 and 180 is not very accurate if the 
style of flask was changed. Explain. Mark the standardized ther- 
mometer for future identification with a piece of cord or wire in the 
loop. 

QUESTIONS 

1. Define the boiling-point. 

2. Give some of the errors in the ordinary method for deter- 

mining the boiling-point. 

3. What is a standardized thermometer? a normal ther- 

mometer? 

4. How is the true boiling-point determined? 

5. How may this be done for ordinary laboratory conditions? 

6. What is meant by the "stem correction"? How is the 

"stem correction" determined practically? How can it 
be obviated? 

7. Why should a cork be softened before using? 

8. When are the different styles (A, B and C) of distilling-flasks 

used? 

9. Why not place the bulb of the thermometer in the liquid? 

10. Why is the flame given a rotary motion at first? 

1 1 . Explain how the porous tiling aids the boiling. 

12. Why should porous tiling not be added to a hot liquid? 

13. What is meant by an "associated" liquid? A "non-asso- 

ciated" liquid? 

14. Why is water used in the condenser? Could mercury be 

used? 

15. When the same quantities of water and aniline are each 

separately distilled from the same flask under identical 
conditions using the same size flame, etc., why does the 
aniline distill faster than the water even though it has a 
higher boiling-point? (This behavior is particularly notice- 
able in the case of brombenzene.) 

1 6. After the plot for the corrections has been made could 

it be used for finding the correction if a distilling-flask 
of different style and size were used instead of one of 
the style and size used when the plot was made? 



Experiment No. 2 

FRACTIONAL DISTILLATION 
Fractionation of a Mixture of Ethyl Alcohol and Water 

Measure separately in a graduated cylinder 50 cc. of ethyl 1 
alcohol (95 per cent) and 50 cc. of distilled water and mix the 
two liquids in a beaker. Note the temperature of the mixture, 
cool to the temperature of the room by setting the beaker in 
water and then measure its volume again. Is it exactly 100 
cc.? Place i cc. of the cooled liquid into an evaporating dish 
and apply a flame momentarily. Do not heat it. Does it catch 
fire? Transfer the dilute alcohol to a clean dry 125-0:. Laden- 
burg distilling flask, 2 add several small pieces of porous tile, 
insert a thermometer, and connect the outlet-tube with a con- 
denser having a straight inner tube. Make two fractionations. 
First Fractionation. This will consist of four fractions. 
For receivers use clean dry Erlenmeyer flasks, two i25-cc. 
and two 6o-cc., and label them from i to 4, using the larger 
ones for the first and last fractions. Have corks ready to fit. 
The temperature intervals at which the fractions are collected, 
as usually taken, are approximately equal. The number of 
fractions depends on the substances and the degree of separa- 
tion desired. In this experiment allow all that comes over up 
to 83 to flow into the receiver labeled No. i. When the tem- 
perature begins to exceed 83 exchange the receiver for No. 2, 
and collect the fraction up to 89, similarly for No. 3, 89+ 
to 96, and No. 4, 96+ to ioo+. 

1 Ordinary alcohol is ethyl alcohol. 

2 A sketch of the Ladenburg distilling flask is given in Fig. 2. It consists 
of a distilling flask and a simple still head (or fractionating column) combined. 
For supporting such a round-bottomed flas"k when unattached, use a suberite 
(pressed cork) ring. 

22 



LABORATORY EXPERIMENTS 23 

Heat the flask first with a rotary motion of the burner. 
Use a small non-luminous flame not more than 2 cm. long. 
When the liquid is distilling regularly, set the burner directly 
under the center of the flask with the flame touching and do 
not remove it during the entire distillation. The drops of the 
distillate should form regularly and at such a rate that they can 
easily be counted, 90-100 a minute. Keep up this rate by very 
gradually increasing the flame. The distillation takes about 
thirty minutes. The slower the distillation the better is the sep- 
aration. On account of superheating, the temperature may go 
slightly above 100 toward the end. It is not necessary to 
distill over all the remaining portion. Add it to receiver No. 4, 
cool under running water, and then measure the amount at the 
ordinary temperature. 

Measure the volume of each fraction, and tabulate the results 
according to the following scheme: 

Fraction I IT ITI IV 

Temperature Up to 83 83+ to 89 89+ to 96 96+ to loo-f 

Volume 20 cc. 31 cc. 8 cc. 40 cc. 

Second Fractionation. To make a further separation distill 
the fractions one after another according to the following pro- 
cedure: Clean out the distilling-flask and pour into it the first 
fraction. After adding some new porous tile distill as above, 
collecting the distillate up to 83 in receiver No. i. As the tem- 
perature begins to rise above 83, although there will still be 
some liquid in the flask, interrupt the distillation by removing 
the burner. When the flask is cool add to it fraction No. 2, 
and again distill until the temperature just exceeds 83, col- 
lecting this distillate in the same receiver, No. i. Now add 
similarly No. 3, and finally No. 4, collecting in each case all that 
distills up to 83 in receiver No. i. After No. 4 has been added 
do not stop the distillation at 83 but continue as in the first 
fractionation, and collect the distillates in receivers 2, 3 and 4, 
at the same temperature intervals as before. 

The new results will appear somewhat as follows: 

Fraction I II III IV 

Temperature Up to 83 83+ to 89 89+ to 96 96+ to 100 

Volume 47 cc. 0.5 cc. 7.5 cc. 43.5 cc. 



24 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Apply a flame to fraction No. i. Does it kindle now? 

A third fractionation made as described under the second 
fractionation would lead to a more thorough separation because 
of the altered composition of the fractions. Furthermore, any 
single fraction may be subjected to a similar process of fraction- 
ation by means of which its separation into alcohol and water 
could be made more nearly complete. 

A mixture of ethyl alcohol and water containing 95.57 
per cent of alcohol by weight has a minimum boiling-point, 
78.15 (760 mm.), so that it is not possible by distillation alone 
to make a separation beyond this point. Pure alcohol boils 
at 78.30. Alcohol of 90.7 per cent has the same boiling-point 
as pure alcohol. 

NOTE 

The results given in the tables were obtained under the condi- 
tions described above, that is, the distillate came over at the rate 
of about 90-100 drops a minute. Under similar conditions, but 
using an ordinary distilling flask instead of the Ladenburg distilling 
flask, the results are somewhat as follows: First fractionation, 
12, 31, 8, 40 cc., and second fractionation: 40, 2, 10 and 41 cc., 
respectively. 

References for collateral reading on the fractionation of liquids 
which mix in all proportions: Morgan, "The Elements of Physical 
Chemistry," 5th Ed. (1918), 177; Walker, "Introduction to Physical 
Chemistry," 7th Ed. (1913), 84-6; Washburn, " Principles of Physical 
Chemistry," (1915), 180-1. 

Alex. Smith, "Introduction to Inorganic Chemistry," New Ed. 
(1917), fractionation, 587-8; alcohol and water, 609; other constant 
boiling mixtures, 211-2, 273, 279. 

For the boiling-point curve of mixtures of ethyl alcohol and water, 
see W. A. Noyes and Warfel, Journ. Amer. Chem. Soc., 23 (1901) 
468. 

A still-head described by S. F. Dufton in an article on "The 
limits of separation by fractional distillation," Journ. Soc. Chem. Ind., 
38 (1919), 4<;, is said to be unusuallv efficient. 



LABORATORY EXPERIMENTS 



25 



QUESTIONS 

1. Outline the theory of fractional distillation. 

2. Discuss the fractional distillation of the three different cases 

of liquids which mix in all proportions. 

3. Explain why pure alcohol is not obtained (See No. 2). 

4. Of about what percentage alcohol does the first fraction of 

the second fractionation consist? 

5. Why is the burner not removed after the distillation has 

begun? 

6. Would the first fraction be increased or diminished if the 

flask was protected with a wire gauze during the heating? 

7. What is a "still-head" or fractionation apparatus? See 

Fig. 4. Why used? 




FRACTIONATION APPARATUS 

WITH 
YOUN&S PEAK STILL-HEAD 



FIG. 4. 



Experiment No. 3 
Absolute Alcohol 

The presence of water in alcohol may be shown by shaking 
3 cc. with a very little white anhydrous copper sulfate in a dry 
well-stoppered No. i test-tube. After half an hour note any 
change in the copper sulfate. Explain. 

In the following experiment, ordinary 95 per cent ethyl 
alcohol is dehydrated over quicklime (CaO). It is then dis- 
tilled from the semi-solid residue and collected under anhydrous 
conditions. 

To a looo-cc. flask attach the narrow end of a slanting 
condenser with bulbed inner tube ("reflux" condenser). (Com- 
pare Fig. 3.) The end of the tube should pass entirely through 
the cork so that the condensed liquid will drop free without 
touching the cork. This is a general rule always to be followed 
under similar condit'ons. If there is a small hole near the end 
of your condenser see that it is below the stopper. (What is 
the object of this small hole?) Arrange the apparatus so that 
the flask can be heated on the steam-bath. 1 Pour 300 cc. of 
ordinary alcohol into the flask, slant it and add about 150 
grams of good quicklime, well crushed. (It should not be 
powdered.) Connect, and heat for an hour. During this time the 
alcohol will boil gently. If it condenses rapidly and the liquid 
rises in the condenser, lower the temperature of the bath slightly, 
and if necessary pour water over the flask. During the heating it 
is well to attach the filled calcium chloride tube mentioned 
below. (Why?) 

1 If a steam-bath is not handy or in working order, use a constant-level water- 
bath (Fig. 5). When working with inflammable liquids the flame under the water- 
bath should be enclosed in a chamber surrounded by a wire screen, in other 
words, a "safety water-bath'' should be used. 

26 



LABORATORY EXPERIMENTS 



27 



If the alcohol is allowed to remain in contact with the lime 
for two or three days, heating for one-half hour will be sufficient 
before the absolute alcohol is distilled. 

Prepare a calcium chloride tube 1 by first inserting a loose 
plug of glass wool or cotton into the bulb (not the narrow tube) 
and then almost filling the tube with small lumps of granular 
calcium chloride, free from dust particles, and covering this 



Wafer 



T\ 



JTL 



ftubberTube Connecfton- 



Mjusfoble 
^ Tube 



Overflow to drato 



CONSTANT LEVEL WATER BATH 

CROSS SECT/ON 
FIG. 5. 

with another plug ot glass wool or cotton. To keep the contents 
in place, and also to prevent an undue circulation of air, insert 
a cork containing a short piece of glass tubing open at both ends. 
If the apparatus is allowed to stand overnight, place the cal- 
cium chloride tube in the top of the condenser, fastening the 
narrow end in a cork. 

Also make ready a condenser with straight inner tube, dry 
inside, and a bent glass tube for connecting the flask with the 
larger end of the condenser in the position for distillation. 
The bend of the tube should be just above the cork stopper, and 
the tube should be cut off just below the stopper. (Why?) For 
the receiver attach a clean dry Erlemneyer filter-flask by means 

1 See Fig. 3. 



28 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

of a cork to the lower end of the condenser and connect its side 
tube with the narrow end of the calcium chloride tube by means 
of rubber tubing. Do not close this tube with a stopper during 
the distillation. (Why?) The receiver should rest upon the 
desk when the apparatus is ready for use. 

Bending Glass Tubing. Hold the dry tube lengthwise in 
the spreading even flame of a wing-top burner. If the wing- 
top does not give an even flame it should be exchanged or 
repaired. Keep turning the tube until it is soft, then remove 
it from the flame and bend to the desired angle. The bend should 
be round and strong, never angular. If the tube is thick or large 
it must be heated in the smoky flame. Always "round" the 
rough edges of all glass tubes by holding them in the flame 
until the edges have melted. This also applies to stirring-rods. 

At the end of the hour cool the contents of the flask by allow- 
ing a stream of cold water to play upon the flask, which should 
be raised slightly in order that the waste water will run into 
the bath. When the alcohol ceases to boil, connect the flask 
as outlined above for distillation, and distill until no more drops 
come over, heating the flask on the steam-bath. Collect the 
first 10 cc. in an open, unattached test-tube, and the remainder 
in the filter-flask. Test the lo-cc. portion and a portion of the 
main distillate for moisture. (?) The distillation may be 
hastened by covering the flask and bent tube with a towel to 
prevent radiation. Sometimes the liquid bumps furiously, 
since all the air has been driven out of the lime. (Compare 
the Boiling-point Experiment, Note 2.) In this case, cool 
thoroughly, add a few pieces of porous tile, then heat again. 

Keep the absolute alcohol in a dry, labeled bottle. It will 
be needed for later experiments. 

Do not empty the waste lime into the sink! 

QUESTIONS 

1. What is formed in the test for water in alcohol? 

2. Why is a bulbed condenser preferable to a straight condenser 

for reflux work? 



LABORATORY EXPERIMENTS 29 

3. Why is the bulbed condenser not used for the distillation? 

Could it be used at all? 

4. Why should the quicklime not be powdered? (Compare 

Note 2, p. 18.) 

5. Why is a calcium chloride tube necessary? 

6. Why must the calcium chloride tube not be stoppered with 

a cork? 

7. Why is the first 10 cc. of the distillate discarded? 

8. Does every part of the distillate as it drips from the con- 

denser contain the same percentage of alcohol? Explain 
fully. (Compare with the curves showing the boiling- 
point and composition of the different mixtures of alcohol 
and water: see Walker's " Introduction to Physical 
Chemistry," yth Ed. (1913), 85.) 

9. Is the "absolute alcohol" prepared in this way absolutely 

free from water? 

10. How can the driest ethyl alcohol be- prepared? 

11. Why cannot the following drying agents be used: calcium 

chloride; cone, sulfuric acid; phosphoric anhydride; 
solitf potassium hydroxide? 



Experiment No. 4 
Tests for Carbon and Hydrogen in Organic Compounds 

1. Effect of heat alone on an organic substance: a. Place a 
little cane sugar in a porcelain evaporating dish and heat gently 
with a small blue flame. 

b. Repeat the above experiment, using benzoic acid instead 
of cane sugar. By using a small flame all the substance will 
sublime without charring, or leaving a residue. (The fumes 
produce coughing when breathed.) 

2. Carbon and Hydrogen can be detected in organic com- 
pounds by oxidation: 

In a porcelain evaporating dish dry about 2 grams of cupric 
oxide powder by heating to dull redness for several minutes. 
While it is cooling, heat a piece of glass tubing (6 mm.) about 
15 crn. long in the Bunsen flame at a point 10 cm. from the end, 
and as it softens slowly draw it out and seal it. Intimately 
mix a very small amount of benzoic acid (from the end of a 
knife blade) with half the warm cupric oxide, transfer this to 
the 10 cm. sealed tube and add the remaining cupric oxide. 
Tap the tube horizontally on the desk so as to make a 
channel above the mixture and clamp it near the open end 
in a horizontal position. Connect it with a short piece of 
rubber tubing to another length of glass tubing bent at right 
angles and leading just below the surface of 3 cc. of clear lime 
water contained in a No. i test-tube. Now gently heat the 
layer of pure cupric oxide and then the mixture. What evidence 
is there of the formation of water and of carbon dioxide? 

QUESTIONS 

1. What is sublimation? 

2. Why is the glass tube not sealed by simply melting the edges 

together? 

3. What causes the reddish-brown color in the tube after the 

heating? 

4. How are carbon and hydrogen determined quantitatively? 

30 



Experiment No. 5 

FORMATION OF A PARAFFIN HYDROCARBON BY REDUCTION OF 
A HALOGEN DERIVATIVE 

Methane from Chloroform and Chemical Properties of the 
Paraffin Hydrocarbons 

Fasten a 125 ex. Erlcnmeyer flask upright with a clamp, 
and place into it 10 grams of zinc dust 1 and 15 cc. of alcohol 
and 10 cc. of water. Insert a bent glass tube through a well- 
bored tight-fitting cork and connect with a short tube leading 
to a beaker or small pail of water arranged so that the gas that 
is formed may be collected by displacement. Now add to the 
flask 5 cc. of chloroform and 2 cc. of a ^V molar solution of cop- 
per sulfate. The reaction will soon begin spontaneously. It 
may even be necessary to moderate it by cooling the flask with 
some water. Collect two test-tubes of the gas, discarding the 
first one, and then in addition fill two 2 glass-stoppered bottles 
of the capacity of the test-tubes. 

a. Ignite the gas in the test-tube (Wrap the test-tube 
in a towel before doing so, because if the methane contains 
air an explosion might result of sufficient violence to shatter 
the tube.) Immediately after the gas is burned add 2 cc. of 
lime water, stopper and shake. What causes the turbidity of 
the solution? Why does the gas made by this method burn 
with a green flame? Is this characteristic of pure methane? 

b. To a bottle of the gas add 2 cc. of bromine water and 
shake. Is there any change in color? Explain. 

c. To 5 cc. of benzine ( u benzolene," not benzene, see Note i) 
add i cc. of a solution of 5 grams of bromine in 100 grams of 

1 See Note regarding weighing out chemicals, p. 3. 

2 One extra, in case a second trial of one of the tests is required. 



32 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

carbon tetrachloride. Divide into two portions, set one in the 
dark and the other in direct sunlight. After several minutes 
compare them. What has happened in the one exposed to sun- 
light? Breathe across the top of the tubes. What does the 
formation of a cloud of vapor indicate? 
d. Stability of paraffins toward reagents: 

1. Add several drops of benzine to i cc. of cone, sulfuric 
acid. Shake. Is there any evidence of chemical action apparent 
by the formation of heat or by darkening? Does the mixture 
become homogeneous? Pour it slowly into cold water, cool 
further if necessary, stir, and then pour it into a small (No. i) 
test-tube. Is a homogeneous solution obtained? 

2. Repeat, using fuming sulfuric acid. Be careful when 
pouring the solution into water. Do so drop by drop. Pour 
upon ice if possible. (?) 

3. Repeat, using cone, nitric acid. (?) 

4. To i cc. of a very dilute solution of potassium perman- 
ganate (just rose color) add several drops of benzine. Shake. 
(Do not use a cork stopper.) Do you notice any change? 

The above general reactions with bromine, sulfuric acid, nitric 
acid, and permanganate are given not only for showing the 
inertness of the paraffins, but also for laying the foundation of a 
general comparison of the properties of other types of hydro- 
carbons as shown by their reactions toward these same reagents. 
See under ethylene, acetylene, and benzene. 

NOTES 

i. The benzine used in the above tests is a fraction of petroleum 
usually taken between 70 and 80. It must not be confounded with 
benzene, CeHo, which boils at 82. The compounds in pure benzine 
will react only very slowly with fuming sulfuric acid and the sulfonic 
acids formed are, like most sulfonic acids, soluble in water. The 
ordinary benzine sometimes contains impurities, probably "un- 
saturated" hydrocarbons formed in the large-scale distillation, and 
these substances are rapidly attacked by even cone, sulfuric acid and 
charred. These things must be borne in mind when interpreting 
the results in this particular case. 



LABORATORY EXPERIMENTS 33 

Since benzine and benzene are both pronounced the same, con- 
fusion as to which is meant often arises. Therefore it has been well 
suggested that the term "benzolene," which corresponds to the 
neighboring fraction, gasolene, be used instead of "benzine." 

2. Opening sealed bottles: Wrap a towel around the bottle, 
leaving the neck exposed, and make a file mark on the neck. Then 
melt the end of a stirring rod in the flame and immediately touch 
the file mark with the melted glass. Generally this causes the glass 
tube to crack. If this fails the end of the neck may be knocked off 
with a sharp blow of the file. In any case, the bottle should be held 
over a casserole or beaker so that if the bottle is cracked the con- 
tents will do no damage. The fuming ac d may be kept for a short 
time for laboratory use in a small glass-stoppered bottle. 

3. Opening bromine bottles: The glass stoppers in bromine 
bottles are often "frozen" and are difficult to remove. If the method 
given in the general notes, p. 4, does not prove effective, the neck 
of the bottle must be broken off. Have ready a funnel large enough 
to hold the entire bottle, supported in a stand, and another bottle 
underneath ready to receive the bromine, all set near the draft pipe. 
Make a file mark around the neck, wrap the bottle all over with a 
towel, and while it is securely held in an upright position strike the 
top a sharp blow with the file or a small hammer. Carefully remove 
the towel, protect the hand with a towel or glove, and pour the 
contents into the funnel. Be sure that you hold the bottle in such a 
way that the bromine will not run down on your fingers, and hold 
the entire bottle over the funnel in order that none will run outside 
See p. 6 for treatment of bromine burns. 

QUESTIONS 

1. What is the purpose of the copper sulfate solution? 

2. Why is alcohol added to the mixture of zinc dust, etc.? 

3. Why is the first test-tube of the gas discarded? 

4. Why is carbon tetrachloride used as a solvent for bromine 

in these tests instead of water? (Noyes and Mulliken, 
"Class Reactions and Identification of Organic Sub- 
stances," 3d Ed. (1915), 8.) 

5. What is the object of pouring the mixture of benzolene and 

cone. H2SO4 into water? (Compare properties of sulfonic 
acids.) Why is a "small, No. i, test-tube" used? 

6. Are the paraffins ever acted upon by HbSO* or HNO.,? 



34 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

7. Give two other general methods (applicable to the entire 

paraffin series) of forming ethane. 

8. Why must a cork stopper not be used when making the 

permanganate test? 

9. What is the main constituent of the benzolene used? Could 

it be obtained pure by fractional distillation? 
10. Why does the gas as prepared in this experiment burn with 
a green flame? 



Experiment No. 6 

FORMATION OF AN ALKYL HALIDE BY THE REPLACEMENT 
OF AN ALCOHOLIC HYDROXYL GROUP WITH HALOGEN 

Preparation of Ethyl Iodide from Ethyl Alcohol 

To 2 grams of red phosphorus and 10 cc. of absolute ethyl 
alcohol in a glass-stoppered bottle add in small quantities 17 
grams of powdered iodine. Shake and cool if necessary after 
each addition by immersion in water. Stopper the bottle and 
set it aside for twenty-four hours or longer. Then transfer 
the reaction-mixture to a small round-bottomed flask, rinse out 
the bottle with 2-3 cc. of absolute alcohol and add the rinsings 
to the main solution. Heat under a reflux condenser on the 
steam-bath for fifteen minutes. Then cool and dry the out- 
side of the flask, connect with a straight water condenser by 
means of a bent glass tube, and distill 1 with care (without using 
a thermometer) until no more liquid passes over. The mixture 
will bump somewhat and this can more or less be avoided by 
keeping the flame in motion. Put the distillate into a Squibb's 
separatory funnel, 2 add some water and test with litmus. (?) 
Add a dilute solution of sodium hydroxide, 3 stopper securely 
and agitate gently in the following manner: Invert the funnel, 
holding the stopper in with one hand and placing the thumb 

1 Use a small flame Excessive heat may decompose the phosphorous acid 
formed in the reaction, giving phosphine. 

2 Fig. 6. When in use the stop-cock should be greased with a good stop- 
cock lubricant. Vaseline may be used, but it is not recommended, since it is too 
"thin" and has no "body." Be sure to clean the separatory funnel before leaving 
the laboratory, so that the stopper and the stop-cock will not stick. It is well 
to keep the ground parts separated but tied with a piece of twine. The separatory 
funnel is conveniently supported in a ring which is clamped to a stand. 

3 Cold dilute sodium hydroxide solution causes no appreciable hydrolysfs 
under these conditions. 

35 



3& LABORATORY MANUAL OF ORGANIC CHEMISTRY 

of the other hand on the handle of the stop-cock and the first 
two fingers on the other side of the stem, and shake. While 
it is still inverted open the stop-cock to release the pressure. 
(?) Repeat both these operations several times. Turn the 
funnel right side up, support it in a ring and as soon as the 
mixture has separated 1 into layers, remove the upper stopper, 
(Why?) and then allow the heavy lower layer of ethyl iodide 
to flow into a clean beaker, cutting off the stream when the upper 






SEPARATION FUNNEL 

(GLOBE. SHAPE) 



SQU/BB'S 
SEPARATOR* FUNNED 



DROPPING 
FUNNEL 

sNOTE NARROW 
J OUTLET TUBE 



FIG. 6. 



layer flows through the stop-cock. The ethyl iodide is usually 
turbid on account of the presence of water. If the brown color 
(?) has not been removed and if the aqueous layer is not alkaline, 
treat it with a second portion of sodium hydroxide solution. 

1 Alkaline solution , sometimes form difficultly separable emulsions. If the 
separation is not complete within an hour and if It is inconvenient to let it stand 
overnight, add dilute acid until the mixture just reacts acid. This procedure 
will usually break up an ordinary emulsion. 



LABORATORY EXPERIMENTS 37 

Separate as above. Remove any water from the stop-cock and 
the stem, and again return the lower layer for one more washing 
with water. This time make a very careful separation, 1 allowing 
the lower layer to run into a small dry Erlenmeyer flask. The 
liquid still contains a small amount of water, although there 
may not be enough to make it turbid. This last trace of water 
is removed by allowing the liquid to, remain in contact with 
a good drying agent such as calcium "choride for several hours, 
or better overnight. Add several pieces of granular anhydrous 
calcium chloride, stopper the flask, (Why?) and set aside until 
the next laboratory period. The Erlenmeyer flask is used in 
order that practically all the liquid may be in close proximity 
to the drying agent. Such flask should never be more than half 
full. For a discussion of drying agents, etc., see Gattermann, 
" Practical Methods of Organic Chemistry, 3d Amer. Ed., pp. 
53-6; and Weyl, "Die Methoden der Organischen Chemie," 
II (2) (1911), 1357-64. 

When the liquid is clear and dry filter it through a funnel, 
containing a small plug of glass wool pushed well down in the 
stem, into a small dry distilling flask (the stem of the funnel 
should reach below the opening of the delivery tube), but do not 
allow any of the droplets of the solution of calcium chloride that 
may be present to flow into the flask with the dry ethyl iodide. 
Distill through a water condenser with a straight dry inner tube, 
using a dry, weighed specimen bottle 2 as the receiver. 3 Ethyl 
iodide boils at 72 cor., and its specific gravity is 1.994 (14). 
Compounds containing a halogen, and particularly those con- 
taining iodine, have a tendency to decompose on strong heating. 
Therefore a very small flame should be used in this instance, 
and the heating should not be continued until the last traces are 
decomposed because some of the products, which are colored, will 
pass over and contaminate the pure distillate. Yield, 16 grams. 

1 If drops of ethyl iodide float on the water, they can be made to drop to the 
bottom by sudden jars to break the surface tension, or by filling the funnel with 
water, thereby lessening the area of the upper surface. 

2 See p. i. 

3 A turbid distillate shows the presence of moisture. It must be dried again 
over night with fresh calcium chloride. 



38 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

What is the corrected boiling-point? Calculate the theo- 
retical yield on the basis of the alcohol used, also of the iodine, 
and compare with the actual results. What is the percentage 
yield on each basis? The product becomes dark on standing, 
especially in the presence of light. A globule of mercury placed 
in the bottle will keep the specimen colorless. (Why?) 

Bottle the product, label as directed in the " Notes," p. i, 
and place in the proper tray for inspection by the instructor. 

Before handing in the preparation perform the following 
experiments : 

a. Test the action of silver nitrate solution on a drop of 
ethyl iodide. Is there an immediate precipitate? Repeat with 
chloroform. (?) 

b. Dissolve i gram of potassium hydroxide in 10 cc. of 
alcohol. Use the KOH marked " purified by alcohol." l To 
i cc. of this solution, which is commonly known as " alcoholic 
potash," add nitric acid until the solution reacts acid, and then 
add distilled water to dissolve any precipitate. (?) To this 
solution add a drop of silver nitrate solution. Is there any 
precipitate or is the solution turbid? (Why?) 

c. Boil i cc. of " alcoholic potash " containing one drop (no 
more) of ethyl iodide for one minute. Cool and acidify with 
nitric acid, dissolving any precipitate (?) with distilled water. 
If an emulsion is formed add alcohol, or repeat, using a smaller 
amount of the halide. Then add a drop of silver nitrate solution. 
Is there aft immediate precipitate? How do you account for it? 

Reference for the preparation of alkyl iodides in large quantities, 
Adams and Voorhees, Journ. Amer. Chem. Soc., 41 (1919), 789-98. 

QUESTIONS 

1. Could yellow phosphorus be used in preparing ethyl iodide? 

(See reference to Adams and Voorhees, p. 31.) 

2. Why is a glass-stoppered bottle used? 

1 If this is not available, dissolve some ordinary stick potassium or sodium 
hydroxide in absolute alcohol and filter from any chloride or carbonate. Or use 
a solution of metallic sodium in alcohol. In the latter case only clean bright 
sodium should be used, the parings being returned to the bottle. 



LABORATORY EXPERIMENTS 39 

3. Why is absolute alcohol used? 

4. Why is the reaction mixture set aside overnight? 

5. Why is the bottle rinsed with a small amount of alcohol? 

6. Account for the formation of the hydrogen iodide which is 

evidenced by the cloud of vapor when the reaction- 
mixture is transferred. 

7. Why is a thermometer not used in the first distillation? 

8. When \sfnsed calcium chloride used for drying liquids? 

9. What causes the " brown color "? How is it removed? 

Write the reactions. 

10. How does the mercury keep the specimen colorless? 

11. Give two other methods for forming ethyl iodide. 

12. Why cannot ethyl iodide be prepared by the direct action of 

iodine on ethane? 

13. Compare the preparation of ethyl iodide and of hydrogen 

iodide. 

14. Why is the halogen in alkyl halides not generally precipi- 

tated with silver nitrate solution? 

15. What is the qualitative test for halide-ion in aqueous solu- 

tion? 

16. What is the brown precipitate formed when not enough 

nitric acid has been added to make the solution react acid? 

17. What would happen in (c) if aqueous potash were used? 

Try it. 

1 8. What is a general method of detecting the halogens in organic 

compounds? Can the sodium-decomposition be used if 
nitrogen is also present? Compare Expt. No. 28. 

19. What impurities does the ordinary potassium hydroxide 

contain? Acidify a dilute solution of potassium hydroxide 
with nitric acid and add silver nitrate solution. (?) 

20. How are the halogens determined quantitatively? 

21. What is alkylation? 



Experiment No. 7 

FORMATION OF AN OLEFINE HYDROCARBON 

AND 
ADDITION OF A HALOGEN TO AN OLEFINE HYDROCARBON 

Preparation of Ethylene (Ethene) and Ethylene Dibromide 
(1.2-Dibrom-ethane) 

In this experiment ethylene is prepared by heating ethyl 
alcohol and phosphoric acid, and the ethylene thus made is 
purified by passage through cone, sulfuric acid and then run 
into bromine, which absorbs it with the formation of ethylene 
dibromide. After the ethylene dibromide is made, the gas 
itself is collected and studied. 

Set up the apparatus shown in Fig. 7. Use rubber stoppers. 

Care must be exercised in putting the glass tubes through 
the rubber stoppers. Be sure to round the edges of all tubes 
in the flame. (See p. 28.) Use a drop of water or of glycerine 
as a lubricant. Always take hold of the tube near the stopper 
and twist it slowly as it is carefully being forced in. Never, 
for example, grasp a long thermometer at one end to push the 
other end through the stopper. With these precautions acci- 
dents resulting in more or less serious cuts would be avoided. 

As a rule it is not necessary to enlarge the hole in a rubber 
stopper. In case a larger hole is required a cork borer can be 
used. It must be moistened frequently, and only very slight 
pressure is needed, otherwise a tapering hole will be made. 

The connections with rubber tubing are easily made if you 
breathe through the rubber tubing before pushing it over the 
glass. Here again the sharp edges of the glass tube should be 
well rounded in the flame. 

40 



LABORATORY EXPERIMENTS 



41 



Fit a 250 cc., round-bottomed, short-necked flask with 
a three-holed stopper through which pass a thermometer, a bent 
outlet tube, with the bend near the stopper, 1 and an inlet tube 
drawn into a narrow tube, 1.5-2 mm. in diameter, with the 
lower end bent upwards about 5 mm. The size of this tube 
is important. If it is larger or smaller than designated it will 
not deliver the alcohol properly. The tapering should begin 




(0 



(3; 



Empty safety turtle ^Br jjjj fl/ a ott 



Diagram of </?pparaf-us 
for Efhylene Di bromide 

FIG. 7. 

just below the stopper and the tube should extend almost to the 
bottom of the flask, so that the alcohol can be delivered well 
below the surface of the liquid. Turn the bend away from the 
thermometer. 

1 The apparatus should be so arranged that the alcohol which condenses below 
the first bend in the outlet tube will not drip upon the lower part of the ther- 
mometer and cause it to crack. In order to avoid back flow of any condensation 
liquid slant the outlet tube as shown. 



42 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

To make the inlet tube, heat evenly a piece of glass tubing 
held lengthwise in the flame of a burner provided with a wing- 
top, rotating it and moving it from left to right until it becomes 
very soft, then remove it from the flame and slowly at first and 
then much more rapidly draw it out as desired. Very rapid 
drawing makes the tube too narrow. It must be made in one 
heating. A smoky flame need not be used as long as the tube 
is slowly warmed in the blue flame. The narrow tube is easily 
broken where a file mark is made. It is bent by softening the 
tube near the end in the flame and quickly touching the end to a 
hard surface when it will bend very readily. Do not fuse the 
capillary or change its bore. 

Connect a dropping-funnel (Fig. 6) with rubber tubing to the 
upper part of the inlet tube above the stopper, and wire the connec- 
tions. 1 Lead the gas (i) through an empty 250 cc. wide-mouthed 
bottle as a safety bottle, using a three-holed stopper. The three 
tubes in this stopper should be cut off just below the stopper. 
Insert a glass stop-cock and attach a piece of rubber tubing to 
lead away the gases to the draft pipe. From this bottle lead the 
gas through a long high glass tube into (2) a 2 cm. test-tube 
with side neck, where it is washed by passing through 10 cc. of 
cone, sulfuric acid. This test-tube should be provided with an 
open safety tube 30 cm. long which should be drawn out and bent 
slightly upwards at the bottom, opening under the surface of the 
liquid. The long high connection is used in order that the 
operator may be able to see the cone, sulfuric acid rising in case 
of back pressure in the apparatus and have time to prevent its 
being drawn into the first bottle by equalizing the pressure 
by opening the stop-cock momentarily. Then (3) through 
another test-tube with side neck containing 7 cc. of bromine 2 

1 This rubber connection must be wired since the rubber absorbs alcohol and 
swells so much that the joint becomes loose 

2 Not bromine water. Do not add the bromine until just before the experi- 
ment is begun. If the bromine is allowed to stand in the tube for several days 
before the experiment is begun it attacks the rubber stopper. Colored compounds 
are formed which run down the walls into the bromine. Since their color is red or 
reddish-brown th.y make it very difficult to tell when all the bromine is decolor- 
ized with the ethylene. Always handle bromine near the draft pipe or under 



LABORATORY EXPERIMENTS 43 

covered with 10 cc. of water. The two tubes leading the gas 
into the sulfuric acid and into the bromine should be drawn 
out to a small opening so that the issuing bubbles will be small. 
Both tubes should open near the bottom of the test-tubes. The 
two test-tubes can conveniently be arranged and supported on 
one ring-stand. Set the first bottle and the two test-tubes in 
beakers full of cold water. Finally (4) through a tube opening 
just above the surface of a normal sodium hydroxide solution con- 
tained in a bottle provided with a vent. Or the bromine vapors 
may be adsorbed by passing the gas through a calcium chloride 
tube filled with adsorbent charcoal. In either case lead the gases 
finally into the draft pipe. 

Into the generating flask put a mixture of 40 cc. of syrupy 
phosphoric acid (sp. gr. 1.7) and 20 cc. of alcohol. Almost fill 
the main bulb of the dropping-funnel with alcohol, and in 
order to displace the air in the tube allow some of the alcohol 
to flow into the flask. Heat the flask over a wire gauze until the 
thermometer in the mixture indicates 230. Only a small 
flame is necessary after the flask is heated through. During 
the preliminary heating have the stop-cock open. When the evo- 
lution of ethylene has well begun close the stop-cock, and let 
the alcohol run in slowly at such a rate (about one drop a second) 
as will give a good constant stream of gas. Keep the tempera- 
ture between 23o-25o. Drafts cool the flask and cause such 
a back pressure that the sulfuric acid and bromine may be 
drawn into the preceding bottles. This back flow may readily 
be avoided by opening the stop-cock, as mentioned above. 
The liquid in the flask should appear as if filled with bubbles 
and will foam as the ethylene is regularly generated. The tem- 
perature may rise even above 250 but should not be allowed to 
reach 300. Continue the passage of the gas until the bromine 
has changed completely to a straw-colored liquid. This will 

the hood. If you get any on your hands wash it off immediately with alcohol, 
and then rub in some carron oil (half linseed oil and half lime water) or carbolated 
vaseline. Benzene and gasoline are good solvents and may also be used for remov- 
ing bromine. See p. 6. 

For opening bromine bottles, c'ompare Note 3, under Methane, p. 33. 



44 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

take about thirty minutes. Much more time will be necessary 
if the gas is not delivered near the bottom where it will stir 
up the bromine and be more readily absorbed. Purify it accord- 
ing to the directions given below. 



NOTES ON THE GENERATION or ETHYLENE 

1. Be sure to open the stop-cock before turning out the flame. 

2. The generation of the gas may be stopped and resumed at 
any time. 

3. When carrying out this experiment it is well to protect the 
eyes with goggles. 

4. Do not try to burn the gas leaving the apparatus unless the 
end of the delivery tube is drawn into a capillary opening. (Why?) 

5. The method can be used for preparing fairly large quantities 
of ethylene. However, the phosphoric acid attacks the glass and 
after about 16-20 hours running the inlet tube is generally "eaten 
off " and finally the flask itself will leak. 

After the color of the bromine has disappeared disconnect the 
second test-tube, connect the outlet tube of the sulfuric acid tube 
with a tube leading to a beaker or small pail of water, and when a 
test-tube of the gas collected over water burns quietly fill, two 
250: cc. narrow-necked, glass-stoppered bottles and a 250 cc. 
ordinary wide-mouthed bottle with the gas by displacement. 

a. Into one narrow-necked bottle pour i cc. of bromine water. 
Insert the glass stopper immediately and shake. (?) 

b. To the second narrow-necked bottle add i cc. of a very 
dilute solution of potassium permanganate. 1 Close with the 
glass stopper and shake vigorously. (?) 

c. Ignite the gas in the wide-mouthed bottle (near the draft 
pipe) and immediately add water to displace the gas. Is the 
flame distinctly luminous? 

Repeat the above experiments using city gas. Conclusions. (?) 

1 For the oxidation of ethylene, see Stoddard, " Introduction to Organic Chem- 
istry," p. 156; of other defines, see Moore, "Outlines of Organic Chemistry," 
2nd Ed., p. 129. 



LABORATORY EXPERIMENTS 45 

Test amylene or pinene ior the "double bond" as follows: 
Use i cc. in each case. 

a. Add i drop of cone, sulfuric acid. (Care!) Result? 

b. Add i drop of cone, nitric acid. (Care!) Result? 

c. Add a solution of bromine in carbon tetrachloride. (?) 

d. Add i cc. of potassium permanganate solution as above 
and shake. (Do not use a cork stopper.) 

Compare the results with those obtained with benzine. 
(Expt. No. 5, p. 31.) 

Transfer the crude ethylene dibromide to a Squibb 's separa- 
tory funnel: add some dilute sodium hydroxide solution; agitate 
gently, and separate. 1 Return the heavy liquid to the separator^ 
funnel, and treat again with a dilute solution of sodium Tiy- 
droxide unless the aqueous layer remained alkaline in reaction. 
Finally wash once with water, and draw off into a dry Erlenmeyer 
flask. The product may be slightly colored. This is due to the 
fact -that some decomposition took place on account, of the heat 
of the reaction between the ethylene and bromine with the 
formation of a small amount of colored by-products. This color 
cannot be removed with alkali. Add several pieces of calcium 
chloride to the cloudy ethylene dibromide, cork the flask (?), 
and set aside for several hours (overnight) to dry the liquid. 
Filter through a funnel containing a plug of glass wool in the 
stem into a dry distilling flask, just as in the ethyl iodide experi- 
ment, but do not allow any of the droplets of the calcium chloride 
solution 2 that may be present to flow into the flask with the dry 
ethylene dibromide. (Why?) Distill through a water condenser 
with dry inner tube, using a dry- weighed specimen bottle as the 
receiver, observing the precautions mentioned under ethyl 
iodide. The substance boils at 131.2 cor., melts at 9.5, and 
its specific gravity is 2.1774 (2i/4)- Yield, 20 grams. Cal- 

1 For separating an emulsion, see foot-note, p. 36. 

2 If there is a layer of calcium chloride solution, even though some of the solid 
is still present, it is quite probable that the product is not very dry. It should 
be separated, treated with fresh calcium chloride, and allowed to stand for several 
hours longer. 



46 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

culate the theoretical yield from the amount of bromine used. 
What is your corrected observed boiling-point? 

Repeat tests a and c as given under ethyl iodide (p. 38), with 
pure ethylene dibromide, and compare the results with those ob- 
tained with ethyl iodide. Write the equations. 

NOTE ON TAKING APART THE APPARATUS 

The glass tubes often stick in the rubber stoppers. In such cases 
do not try to pull out the tube directly. Work the rubber away from 
the tube with the fingers and allow water to flow in and moisten it 
as fast as it is separated. In this manner the tube soon becomes free 
and can be withdrawn easily. 

QUESTIONS 

1. What objection is there to an inlet tube with a diameter 

less than 2 mm.? Greater than 2 mm.? 

2. Why must the alcohol be delivered below the surface of the 

liquid? Why is the inlet tube turned up at the bottom? 

3. What substances are caught in the empty safety bottle? 

Account for them. Is this the only purpose of this 
bottle? 

4. Why must the gas be passed through cone. EbSCU? Could 

fuming H2SO4 be used? dilute H 2 SO4? 

5. Why should the alcohol vapors not be allowed to go over 

into the bromine? 

6. Why are the bottles surrounded with cold water? 

7. Why is the bromine covered with a layer of water? 

8. What substances are caught in the sodium hydroxide solu- 

tion? Account for them. 

9. Why is the apparatus disconnected before extinguishing the 

flame? 
10. What is the brown precipitate formed in the permanganate 

. test? 

n. What unsaturated hydrocarbons are in the city gas? What 
are illuminants? Name some. 

12. How are the unsaturated hydrocarbons in illuminating gas 

estimated? 

13. Is an addition or substitution product formed with amylene 

and sulfuric acid? 



LABORATORY EXPERIMENTS 47 

14. In the purification of ethylene dibromide why must the 

sodium hydroxide solution be used? 

15. Why avoid the emulsion which would be formed by vigorous 

shaking? 

16. Why is a 250 cc. Squibb's separatory funnel used instead of a 

dropping-funnel although the volume of liquid is small? 
(Fig. 6, p. 36.) 

17. Why not dry the product in a small distilling flask and 

distill directly without removing the calcium chloride? 

1 8. Why is glass wool used instead of a filter paper in the 

funnel? 

19. What compounds are in the " amylene "? 

20. Look up the formula for pinene. 

21. Why not use the weight of the alcohol instead of the bro- 

mine in calculating the theoretical yield? 

22. Is ethylene dibromide a saturated or unsaturated compound? 

Of what hydrocarbon is it a derivative? 

23. What happens when ethylene dibromide is heated with alco- 

holic sodium hydroxide? Vith aqueous sodium hydroxide? 

24. What other methods can be used for preparing ethylene? 

25. How did the United States Government prepare ethylene in 

large quantities for the manufacture of " mustard gas " 
(dichlor-diethyl-sulfide) during the war? (Ref., Doirsey, 
Journ. Ind. and Eng. Chem., 11 (1919), 288. 



Experiment No. 8 

FORMATION OF AN OLEFINE HYDROCARBON 
Ethylene from Ethyl Alcohol (for Short Course) 

Weigh directly into a large test-tube (No. 3), 4 grams of 
phosphorus pentoxide. Connect the test-tube by means of a 
closely fitting cork with a reflux air condenser; immerse the tube 
in cold water, and pour 5 cc. of ethyl alcohol slowly through the 
condenser. The alcohol should be added cautiously in small 
portions and the test-tube shaken under water, since much heat 
is evolved when alcohol comes in contact with phosphorus 
pentoxide. Remove the condenser, support the test-tube at an 
angle of about 45 with the desk top by means of a clamp, and 
connect it with a delivery tube arranged to collect gas over 
water. Heat the tube carefully until the mixture becomes 
homogeneous; then more strongly until a steady stream of gas 
is evolved. Fill two 250 cc. narrow-necked glass-stoppered 
bottles and a 250 cc. wide-mouthed bottle with the gas over 
water by displacement. 

a. Into one narrow-necked bottle pour i cc. of bromine water. 
Insert the glass stopper immediately and shake. (?) 

b. To the second narrow-necked bottle add i cc. of a very 
dilute solution of potassium permanganate. Close with the 
glass stopper and shake vigorously. (?) 

c. Ignite the gas in the wide-mouthed bottle (near the draft 
pipe) and immediately add water to displace the gas. Is the 
flame distinctly luminous? 

Repeat the above experiments, using city gas. Conclusions. (?) 
Test amylene or pinene for the " double bond " as follows: 
Use i cc. in each case. 

a. Add i drop of cone, sulfuric acid. (Care!) Result? 

48 



LABORATORY EXPERIMENTS 49 

b. Add i drop of cone, nitric acid. (Care!) Result? 

c. Add a solution of bromine in carbon tetrachloride. (?) 

d. Add i cc. of potassium permanganate solution as above 
and shake. (Do not use a cork stopper.) 

Compare the results with those obtained with benzine, 
Expt. No. 5., p. 31. 

QUESTIONS 

i. Compare the action of ethyl alcohol with that of water on 
phosphorus pentoxide. Write structural formulas of the 
compounds in each case and name them. 

2. What is the action of heat on the compounds formed by the 

action of ethyl alcohol and of water, respectively, on 
phosphorus pentoxide? 

3. Write the equation for the reaction of bromine and ethylene. 
4.' What happens when ethylene is treated with dilute potassium 

permanganate? 

5. What is the brownish precipitate formed in the perman- 

ganate test? 

6. Define an addition product; a substitution product. Illus- 

trate. 

7. Is ethylene dibromide a saturated or an unsaturated com- 

pound? Of what hydrocarbon is it a derivative? 

8. Is an addition or substitution product formed with amylene 

and sulfuric acid? 
g. What unsaturated hydrocarbons are in the city gas? 

10. What are " illuminants "? Name some. 

11. How are the unsaturated hydrocarbons in illuminating gas 

estimated? 



Experiment No. 9 

FORMATION OF AN ACETYLENE: i. BY HYDROLYSIS OF AN 

ACETYLIDE 

Acetylene from Calcium Carbide 

Set up a gas generator consisting of a filtering-flask and 
dropping-funnel. Into the dry flask place several lumps l of 
calcium carbide and allow water to drop very slowly upon it. 
(Care!) Pass the gas through an empty safety-bottle and then 
fill with the gas by displacement over water a test-tube, two 
narrow-necked glass-stoppered bottles, and a wide-mouthed 
bottle in the order named. 

a. Ignite the gas in the wide-mouthed bottle, holding it near 
the draft pipe. Notice the luminosity of the flame and the 
amount of carbon deposited. 

b. To one narrow-necked bottle add 2 cc. of bromine water 
and shake. (?) Compare with methane, p. 31, and ethylene, 
p. 44 or p. 48. 

c. To the other narrow-necked bottle add i cc. of a very 
dilute solution of potassium permanganate. Shake. Are there 
any signs to denote unsaturation? 

d. Dilute 0.5 cc. of silver nitrate solution to about 3 cc. 
From a test-tube add this silver nitrate solution to a test-tube 
of the gas. What is the white precipitate? Filter with suction 
and let it dry on filter paper. Explode it by heating small pieces 
in the flame. 2 Note the presence of carbon on the knife blade 
after the explosion. 

e. Prepare a solution of cuprous chloride as follows: Dis- 
solve 0.5 gram of copper sulfate crystals in a little water, add 

1 The powder is generally useless since it is mostly decomposed. 

2 Destroy all the remaining silver precipitates before leaving the laboratory, 
either by explosion or by warming with dilute hydrochloric acid. 

50 



LABORATORY EXPERIMENTS 



51 



2 cc. of cone, ammonium hydroxide and 1.5 gram of hydroxyl- 
amine hydrochloride. Dilute with water to about 25 cc. It may 
be kept colorless by placing it in a tightly corked bottle con- 






taining some copper turnings. The bottle should be full in order 
to avoid oxidation by any air present. This will be used in both 
parts of this experiment. 

Pass acetylene into 5 cc. of the cuprous chloride solution. 
What is the reddish-brown precipitate? Filter the solution 



52 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

with suction and wash the precipitate. Let it dry on the filter 
paper, and then explode small portions of it in the flame Try 
its solubility in dilute hydrochloric acid solution. 

Filtration with Suction. In order to filter with suction fit the 
porcelain Buchner funnel, Fig. 8, p. 51, tightly into the neck of a 
filtering-flask with a good cork or rubber stopper, and connect 
the outlet tube to the filter pump with heavy rubber tubing. 
In the bottom of the funnel place a filter paper cut so that it 
covers all the holes and lies flat without being folded on the sides. 
Moisten the paper with some of the liquid used, start the suction, 
and then pour in the mixture. Oftentimes with bulky material 
it is convenient to press it down with a flat-topped glass stopper. 
At the end of the filtration carefully disconnect the tube from the 
flask before stopping the suction. 

For the filtration of small quantities, see p. 56. 

2. BY THE ACTION OF ALCOHOLIC POTASSIUM HYDROXIDE ON 
AN ALKYLENE DIHALIDE 

Acetylene from Ethylene Dibromide 

To a 100 cc. flask set on the steam-bath attach an addition 
tube with reflux condenser connected with its side opening. 1 
From the top of the condenser run a tube leading into 5 cc. 
of the ammoniacal cuprous chloride solution. Have all con- 
nections tight. Good corks, well bored, must be used. Col- 
lodion sometimes may be used to aid in making a cork gas- 
tight, but it is not a substitute for an evenly bored cork. Rubber 
stoppers may also be used if desired. Heat 2 grams of potassium 
hydroxide, " purified by alcohol/' 2 in 12 cc. of alcohol in the flask 
for about ten minutes. Cool and add through the addition 
tube 2 cc. of ethylene dibromide. Heat again. What is the 
precipitate formed in the cuprous chloride solution? At the end 
of the reaction dissolve the precipitate (?) in the flask by adding 
some distilled water, add nitric acid to a small portion of this 

1 See Fig. 3, p. 13. 

2 Or use an equivalent amount of metallic sodium in alcohol. Connect the 
condenser to the flask after the sodium is added, since the alcohol becomes hot 
and hydrogen is given off. 



LABORATORY EXPERIMENTS 53 

until it reacts acid, and then add a drop of silver nitrate solution. 
What is the precipitate? Account for it. 

NOTE 

Only a small amount of the ethylene dibromide is converted into 
acetylene. The major portion is converted into vinyl bromide (mono- 
brom-ethylene) which is a gas at room temperature and passes out 
of the reaction mixture before it can be reacted upon further and 
completely transformed into acetylene. If no acetylene is detected 
in your experiment it is because there were leaks in your apparatus. 
Some is always formed. 

QUESTIONS 

1. What two compounds may be formed when acetylene and 

bromine react? 

2. What happens when an acetylide is boiled with dil. hydro- 

chloric acid? 

3. What kind of a reaction is the decomposition of calcium 

carbide? 

4. What causes the bad odor of the gas? Source? 

5. What style of acetylene hydrocarbons form metallic deriv- 

atives? 

6. When the copper sulfate is reduced to the cuprous form, 

what becomes of the hydroxylamine? 

7. Why is an ammoniacal solution of cuprous chloride used? 

8. Why is ammonium hydroxide not used also with the silver 

nitrate? 

9. Are all acetylides explosive? 

10. What is meant by an exothermic compound? an endothermic 

compound? 
n. Write the reactions for the formation of acetylene from 

ethylene dibromide, giving the different products formed. 

12. Explain why the acetylene burns with a smoky flame in 

the experiment, while in certain lamps, such as automo- 
bile lamps, it burns with an exceedingly bright flame. 

13. Discuss the reactions, in the treatment of the residual 

" alcoholic potash " solution. 

14. What advantages has a Buchner funnel over the ordinary 

funnel? 

15. In the suction filtration why is the tube disconnected from 

the flask before the water is turned off? 

1 6. Why should the filter paper not be allowed to " run up v 

the sides of the Buchner funnel? 



Experiment No. 10 
Alcohols, Reactions of 

a. Add a small piece of bright sodium to 2 cc. of ethyl alcohol. 
What gas is evolved? What is the white solid that separates 
as the solution cools? Add more sodium if nothing separates the 
first time. Is this reaction characteristic of all alcohols? How 
do you name the compounds formed? 

b. Add a few drops of cone, sulfuric acid to 0.5 cc. of glacial 
acetic acid and i cc. of ethyl alcohol. Warm, with shaking. 
Pour it on a large cover glass and neutralize with sodium car- 
bonate. To what is the pleasant odor due? To what class of 
organic compounds does it belong? 

Repeat, using iso-amyl alcohol. (This alcohol usually pro- 
duces coughing when breathed.) 

c. Make a dilute solution of sodium dichromate, add a drop 
or two of cone, sulfuric acid and then several drops of ethyl 
alcohol. Heat. Notice the odor of the vapors. What is 
formed? What causes the green coloration? 



54 



Experiment No. 11 

THE IDENTIFICATION OF AN ALCOHOL 
The Methyl Ester of 3.5-Dinitrobenzoic Acid 

It is seldom possible to identify organic substances in the same 
general manner as inorganic substances. Class reactions l 
are relied upon to tell the nature of the substance, that is, its 
class, such as a hydrocarbon, an alcohol, etc., and physical con- 
stants will often show what member of the class the substance is. 
Then, in order to make certain, the substance is transformed into 
a derivative which can readily be prepared on a small scale, and 
a physical constant taken upon this. On account of the diffi- 
culties in purifying liquids in small amounts, 2 a solid derivative 
is chosen whenever possible. The following experiment illus- 
trates this point in the case of the lower alcohols. 

In a small dry test-tube heat together 0.3 gram of 3.5-dinitro- 
benzoic acid and 0.4 gram of phosphorus pentachloride over 
a low flame. Keep the tube in motion and finally allow the 
mixture to boil gently for a minute. Then while it is still 
liquid pour the product upon a small dry watch glass. When the 
acid chloride (?) has solidified remove the liquid by-product, 
phosphorus oxychloride, adhering to it, by pressing out the 

1 Noyes and Mulliken, "Class Reactions and Identification of Organic Sub- 
stances," and Clarke, "A Handbook of Organic Analysis." For a more extended 
work, see the three monumental volumes by Mulliken, "Identification of Pure 
Organic Compounds." 

2 For a method of determining the boiling-point of a very small amount of 
liquid, see Mulliken, Vol. I, p. 222; also Alex. Smith and Menzies / Journ. Amer. 
Chem. Soc., 32 (1910), 897. 

55 



56 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

mixture with a porcelain spatula l on the smooth side of a piece 
of clean porous tile. 2 

Put the dry material into another small test-tube, add 
eight drops of methyl alcohol, stopper the tube and shake 
now and then. The reaction is soon complete and after a few 
minutes the ester can be recrystallized. To do this, place the 
product into a 60 cc. flask under a reflux condenser, add 20 cc. 
of dilute alcohol (3 volumes of alcohol and i of water), and heat 
to boiling by heating on the steam-bath or by immersing the flask 
in hot water. If the substance does not completely dissolve after 
a short time add a little more dilute alcohol and boil again. 
There may be some foreign particles which will not go into solu- 
tion. Filter the hot solution through a small filter paper into a 
beaker and allow the filtrate to cool. The ester crystallizes in 
shining leaflets. Separate these by filtering with suction. 

Filtration of Small Quantities with Suction. Use a Gooch 
perforated porcelain plate in a No. i funnel, and place upon 
the plate a piece of filter paper just large enough to cover it 
and extend to the walls of the funnel. Fasten the funnel in a 
stopper in the neck of a test tube with side opening. Moisten 
the filter paper with dilute alcohol, start the suction, and proceed 
as usual. (See Fig. 8, p. 52, and compare p. 52.) 

Allow the crystals to dry between filter papers or under 
a watch glass on a porous tile, and then determine the melting- 
point according to the directions given in Expt. No. 12, p. 58. 
The pure substance melts at 107 (uncor.). 

Other esters 3 of this acid may be employed to identify the 
corresponding alcohols. They may be prepared according to 
the directions given above for the methyl ester. The ethyl 
ester melts at 92 ~93, i-propyl ester, 73; i-normal-butyl 
ester, 64; i-iso-butyl ester, 83-84. 

1 In ordinary cases where no corrosive substance is present a steel spatula can 
be used. It should be cleaned previously with soap to remove traces of rust and 
dirt. 

2 A porous unglnzcd tile is good for one drying, unless only a portion of the 
surface has been used. Obviously it cannot be washed. 

3 Mulliken, "Identification of Pure Organic Compounds," Vol. I (1904), 



LABORATORY EXPERIMENTS 57 



QUESTIONS 

i. Why is the solid ester of 3.5-dinitrobenzoic acid made for 
the identification of an alcohol instead of the liquid ester, 
for example, of acetic acid? 

2 Write the equations for the reactions for preparing the methyl 
ester. (Compare Stoddard, " Introduction to Organic 
Chemistry, 2d Ed. (1918), p. 354, last paragraph, and 
p. 99, No. 3, near bottom of the page, p. 114, No. 2 and 
p. 116, No 3.) 

3. What is the object of the porous tile? Why not use filter 
paper? 



Experiment No. 12 
Determination of the Melting-point 1 

The melting-point is the physical property most generally 
used as a criterion of the purity of a solid organic compound. 
It also serves for the characterization and recognition of a 
compound. On account of its significance the melting-point 
should be very carefully and accurately determined. The method 
employed is to heat a small amount of the substance in a capillary 
tube attached to a thermometer in a suitable bath until the sub- 
stance becomes a clear liquid 2 and the temperature at this point 
is recorded as the melting-point. A substance is regarded as 
pure when it melts within 0.2-0.4 of a degree, 3 provided that the 
temperature is kept as nearly constant as possible, and if after 
repeated crystallization it does not change. Slow melting 
over several degrees usually indicates an impure compound, 
provided the rate of heating is all right. Some pure substances, 
however, especially those of high molecular weight, do not show 
a sharp melting-point in the ordinary method (compare phenyl- 
glucosazone, Expt. 34, p. 129). 

Set up a melting-point apparatus like the one illustrated in 
Fig. 9. It consists of two tubes, one inside the other. The outer 
one is 32 mm. in diameter and about 14.5 cm. long; 4 the inner 
one is 17 mm. in diameter and 14 cm. long, and has a series of 

1 See G. A. Menge, "A Study of Melting-point Determinations," U. S. Hygienic 
Laboratory Bulletin, 70 (1910), for an excellent description and discussion of the 
methods of determining melting-points, common errors, etc. NOTE: This bulletin 
is out of print, but may be consulted in the general library. 

2 Frequently the temperature of decomposition (often coincident with the 
melting-point) is taken, but in this case there is the possibility of a greater amount 
of divergence due to manipulation. 

3 This error is about equal to the error of observation. 

4 The outer tube of a Beckmann freezing-point apparatus is suitable. 

58 



LABORATORY EXPERIMENTS 



59 



small holes l not over 2 mm. in diameter four at each height 
as indicated in the figure. In order that the behavior of the sub- 
stance can be watched there are no holes opposite the bulb of 



MELT/NG-POINT 
TUBE 



CONG. 




2O HOLES 
ZMM.DIAM. 



MELTING -POINT 

FIG. 9, 



the thermometer. The inner tube can be supported in the outer 
tube by means of a cork as shown, with a narrow channel cut 

1 In case an inner tube all perforated is not at hand, the holes can be blown in 
as follows: Select a test-tube of the proper dimensions, stopper it with a good 
cork which carries a glass tube to which is connected a piece of rubber tubing 
for blowing. Heat a tiny area of the glass at the desired point with a fine blast 



60 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

along the edge to allow the heated vapors to escape, or, when the 
thermometer is in position and securely held in alignment by a 
cork, 1 it can be supported by holding the top of the thermometer 
in a clamp. 

The outer tube should be supported by clamping it firmly but 
not too tightly under the lip. Add enough cone, sulfuric acid 
to come up to a height of 6 cm. from the bottom of the inner 
tube when it is in place. 2 The apparatus is heated with a small 
flame which should be protected with a metal chimney. The 
liquid in the inner tube is regularly heated and stirred mainly 
by means of convection currents made possible by the series of 
small holes. The liquid near the thermometer always shows an 
even downward flow all around the stem. 3 Moreover, the inner 
liquid can be heated uniformly and steadily since it is not affected 
by ordinary drafts. 

Make several capillary tubes, the so-called melting-point 
tubes, as follows: Heat evenly a piece of glass tubing held 
lengthwise in the blue 4 flame of a burner provided with a wing 
top, rotating it and moving it from left to right until it softens, 
then remove it from the flame and draw it out very slowly at first 
and then, as the glass begins to cool and harden, much more 
rapidly, into a long, straight, thin-walled, narrow tube of about 

flame, and when it melts remove it from the flame and blow a bubble, not a hole. 
Repeat this at every point. Then complete the making of the holes by melting 
each little bubble or by breaking the glass with a file and "rounding" the edges 
of each hole with the flame. Remember that the holes should be not more than 
about 2 mm. in diameter. 

An apparatus like the one described above but without the holes in the inner 
tube has been in use for many years in different laboratories. It is believed, how- 
ever, that the perforated inner tube is new and is an advantage since it permits 
good stirring and more rapid heating and cooling. 

1 If a long-scale 360 thermometer is used, this cork should have a longitudinal 
section cut out to form a canal through which the degrees of the thermometer 
can easily be read at this interval. 

2 If more acid is used the melting-point tube is likely to drop off in the liquid, 
since too small a length of it is held by capillary attraction. 

3 The currents in the liquid can be seen very nicely if a little finely divided 
carbon is put in the acid. 

4 A smoky flame need not be used provided the tube is slowly warmed in the 
blue flame. 



LABORATORY EXPERIMENTS 61 

i mm., (dz 0.2 mm.), inside diameter. 1 Rapid drawing in the very 
beginning makes the tube too narrow. It must be made in one 
heating. The wing-top should give an even flame. If the flame 
is irregular the glass will not be heated evenly and the narrow 
tube will consequently be uneven. Test-tubes give excellent 
melting-point tubes. They are heated in the ordinary Bunsen 
flame. It is sometimes difficult to make a tube of circular 
cross-section, but the walls are sure to be thin and this is an 
advantage since there will be less glass through which the heat 
must be conducted to the substance. Cut the long narrow tube 
into lengths of 9 cm. by means of file marks (do not try to break 
it otherwise) and seal one end of each tube by carefully heating 
the edges in the outer mantle of a small flame. Do not fuse too 
much of the glass, since this thickens the walls, thus diminish- 
ing the diameter of the tube, and causes the formation of a glass 
bead at the sealed end. Smaller lengths should not be used be- 
cause they will not remain attached to the thermometer as de- 
scribed below. If possible, it is advisable to cut the original 
capillary into lengths of 18 cm. and seal both ends. When 
needed the double-length tube is broken at the center and serves 
for two determinations. 

Make a little mound of dry, powdered 2 substance and force 
some of this into a melting-point tube by gently thrusting the 
open end directly into the material, and giving it a rotary motion 
at the same time. This operation cuts out a little cylindrical 
cake of the substance. Shake this down by letting the sealed 

1 Lengths of 30 to 60 cm. arc readily made in this way. Larger tubing of soft 
glass, such as "bomb" tubes, can be drawn out rapidly, with the aid of an assist- 
ant, into a length of several meters, and a good stock of melting-point tubes cut 
therefrom. 

The advantages of the long straight melting-point tube over the tapering tube 
with a cup at the top which has often been described are threefold : (i) many tubes 
can be made at the same time; (2) they can be attached more easily to the ther- 
mometer; and (3) most organic compounds are light and fluffy, and on this account 
they cannot be made to drop readily to the bottom of the melting-point tube, 
but since the straight tube has an even bore, the little cylinder of material which 
is cut out, as described in the next paragraph above, will usually slide down to 
the bottom without difficulty. 

2 Large crystals do not form a compact mass and therefore the material is not 
heated as evenly and quickly as when powder is used. 



62 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

end of the tube drop gently upon the desk. 1 Repeat until a layer 
3 mm. deep is formed. Rub off the substance adhering to the 
outside of the tube so that it will not be charred by the acid and 
discolor the bath. Remove the thermometer from the apparatus, 
allow most? of the acid to drain off, and touch the bulb to the 
upper part of the melting-point tube, thus leaving behind a 
droplet of the liquid. Place the tube with the sealed end down 
against the thermometer stem and it will adhere by capillary 
attraction. The substance should be opposite the bulb of the 
thermometer. Return the thermometer, with the tube attached, 
to the apparatus. The melting-point tube should extend about 
as far along the thermometer above the liquid as it does in the 
liquid in order that the capillary force will be great enough to 
hold it to the .thermometer. Now begin to heat the liquid 
with a small flame. 2 The heating may be fairly rapid until 
within about 15 of the melting-point (already known or approxi- 
mately determined in a preliminary trial) and then slowly, 
3 a minute, until the substance melts. Do not guess at the 
rale, time it, and then you will obtain consistent results. Sub- 
stances generally soften and contract, and often become dis- 
colored before melting. 

It is absolutely essential to use a small flame, and heat 
regularly, especially when within io-i5 of the melting-point. 
Alternate heating with a large flame never gives consistent results. 
The small flame can easily be obtained if the air supply of the 
burner is properly cut down. Drafts should of course be avoided 
as much as possible. 

The temperature of the bath can be carried up to about 
280 if pure cone, sulfuric acid is used. If water has been 
absorbed the diluted acid will begin to boil at a lower tempera- 

1 If the substance does not drop readily to the bottom of the tube try either 
of the following methods: Hold a piece of ordinary glass tubing, about 60 cm. 
long, open at both ends, in an upright position on the desk and touching the desk 
top, then let the melting-point tube, with sealed end down, drop through it. Repeat 
this several times if necessary. Or, draw the flat side of a triangular file hori- 
zontally across the tube a little below the substance. The powder, loosened by 
the vibration set up in the glass, will quickly slide down to the bottom. 

2 If the burner is held in the hand, hold it in an oblique position in order o avoid 
accident in case the apparatus cracks. 



LABORATORY EXPERIMENTS 63 

ture and cannot be used for the higher temperatures. If it begins 
to boil the heating should be discontinued. The boiling-point of 
the acid may be increased by boiling it in a flask or beaker under 
the hood. 

The errors in this determination are generally due to the vari- 
ation of the thermometer, rate of heating, 1 physical condition 
of the compound, 2 and individual manipulation. For an 
extended discussion of these errors the student is referred to the 
bulletin mentioned in the foot-note above. The true melting- 
point is obtained by the use of short-stem, normal, standardized 
thermometers whose mercury thread is entirely immersed in 
the bath. Since these are expensive and are not always avail- 
able, the set of three short-scale thermometers mentioned in 
connection with the Boiling-point experiment, p. 8 and Fig. i, 
should be used. 

Experience in determining the melting-point and checks on 
the accuracy of the thermometer can be obtained by using 
substances whose melting-points are near the bottom and some- 
what near the top of the scale in each case, as mentioned in 
the first experiment. The following substances are suitable. 
The temperatures given are corrected: 

Naphthalene 80.8 

Benzoic acid 122.5 

Salicylic acid 159 . 8 

Anisic acid 184 . 2 

Anthracene 216 .0 

Carbazol 246 . o 

Anthraquinone 285 .0 

All these substances in addition to giving good melting- 
points have a special advantage in that they are easily obtained 

1 Probably more errors arc made in manipulation by improper heating than in 
any other way. The rate of heating must not be so rapid that an appreciable rise 
of temperature occurs during the time necessary for the attainment of the same 
temperature throughout the entire mass. Otherwise the temperature may rise 
several degrees during the interval between incipient and complete melting. 

2 Compare preceding foot-note, and foot-note 2 , p. 61. 



64 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

and are readily purified by sublimation. 1 It is seldom necessary 
to use a substance melting below naphthalene. If necessary 
one of the following can be used: ^-toluidine, 45; hydrocin- 
namic acid, 48.7; a-naphthylamine, 50; or diphenylamine, 54. 

Compare the results with those obtained with the same 
thermometers in the boiling-point experiment. 

If the set of three thermometers mentioned above is not at 
hand, an ordinary long-scale thermometer may be standardized 
for the conditions obtaining in the laboratory work by determin- 
ing the melting-points of some of the pure substances given in 
the list, for example, naphthalene, salicylic acid, anthracene and 
carbazol. Then by plotting the results on co-ordinate paper, as 
described in note 4, Boiling-point experiment, p. 20, the cor- 
rection for any one degree may quickly be read off at any time. 

The influence of changes in atmospheric pressure on the 
melting-point is negligible. 

The abbreviation " cor." is placed after a corrected melting- 
point. It is to be noted that almost all the melting-points given 
in the literature and the text-books are unfortunately un- 
corrected. 2 Melting-points determined under uncorrected con- 
ditions cannot always be duplicated by other workers. This 
is especially true of melting-points above about 125. 

NOTES 

i. The Thiele melting-point apparatus is shown in Fig. 10. It 
uses a small amount of acid and can be heated and cooled quickly. 
The flame is placed under the bend of the side loop, and the liquid 
is stirred by means of convection currents. The hot current, how- 
ever, usually goes down the side near the loop, and the remainder 
of the liquid is heated mainly by conductance. The temperature 
of the sulfuric acid bath can be carried up to about 250. Then 
the liquid begins to boil, and bubbles sometimes form rapidly and 
exert such pressure in the narrow side loop that the tube may be 
cracked. Very good results can be obtained with this apparatus 

1 For a simple method of sublimation, see Anthraquinone, Expt. 65, p. 210. 

2 The data given in this book are not all "corrected," since they cannot always 
be found in the literature and very pure material has not been available. 



LABORATORY EXPERIMENTS 



65 



when the heating is properly carried out. It is quickly affected by 
drafts. 

2. Discoloration of the sulfuric acid on account of charring of 



C/amp 



Me/ftnj Point 
Tube ' 




Thiele Me/ting -point Apparatus 



FIG. 10. 



organic matter may be prevented to a limited extent by the addition 
of very small amounts of potassium nitrate, sodium persulfate, 
etc., or the discolored acid may be treated with cone, nitric acid and 



66 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

boiled in a flask or beaker under the hood until the fumes of nitric 
oxides are no longer evolved. 

3. A micro-burner is convenient to use for determinations under 
100. 

4. Water can advantageously be used for determining low melt- 
ing-points. 

5. A skillful operator can attach several different melting-point 
tubes to the same thermometer and make all determinations by one 
continuous heating of the bath. 

6. For temperatures between 220 and 320, Mulliken 1 recommends 
a bath prepared by cautiously boiling together for 5 to 10 minutes, 
under a hood, a mixture of 70 parts by weight of cone, sulfuric acid 
and 30 parts of neutral potassium sulfate, and stirring until the 
sulfate is completely dissolved; or by similar treatment of a mixture 
of 55 parts by weight of the acid with 45 parts of acid potassium 
sulfate. The mixture has the consistency of glycerol, does not fume 
badly, and is less corrosive and less easily discolored by traces of 
organic matter than sulfuric acid. By increasing the proportion of 
neutral sulfate from 30 to 40 per cent this bath may be used for 
temperatures up to 370. This mixture, however, is solid at the 
ordinary temperature. 

For temperatures between 370 and 500, fused zinc chloride, 
free from dust, may be employed. 

The student is referred to the reference cited for the method of 
handling these mixtures. 

7. Certain substances which decompose at high temperatures 
giving of! water vapor, carbon dioxide, or ammonia, give better melting- 
points when heated in melting-point tubes sealed at both ends. 
Complete data as to size of tube, quantity used, etc., are necessary 
for comparison, because they will vary many degrees with a change 
in conditions on account of the differences in the gas pressures of 
the decomposition products. 

Similarly substances which readily sublime are sometimes heated 
in melting-point tubes sealed at both ends. 

8. It is not always possible to determine the melting-point a 
second time on the same sample previously melted in the tube, since 
in many cases the substance decomposes. It should also be mentioned 
that in some cases the substance undergoes a change in its crystalline 
condition, being converted from an unstable form into the stable 

1 "Identification of Pure Organic Compounds," Vol. I, 218-9. 



LABORATORY EXPERIMENTS 67 

form, 1 like iodine monochloride, and phosphorus. For example, 
the labile or metastabile form of benzophenone melts at 26, but 
after having been melted and allowed to solidify, if heated again, 
it is found to melt at 48. Sometimes the difference is much greater 
than in this example, sometimes it is very much less. The changes 
from one form to the other may be very rapid or very slow. If the 
melting-point is taken very slowly the metastabile form may be 
transformed into the stable form and only the melting-point of the 
stable form actually noticed. . 

In other cases the stable form may have the lower melting-point. 
The stable form of benzaldoxime melts at 34-5 and the unstable 
at 130. TheiL-e two forms, however, are isomeric, 2 not polymorphic 
like benzophenone, and the change is supposed to be stereoisomeric. 

Furthermore there are a few known cases where the substance 
melts sharply at a definite temperature to a milky liquid, which 
on being further heated suddenly becomes clear also at a definite 
temperature. On cooling the reverse series of changes occurs. Since 
these milky or turbid liquids show properties of both liquids and 
?olids they have been called liquid crystals? The crystalline structure 
of the turbid liquid cannot be detected by the microscope, but is 
Indicated by the double refraction exhibited by the liquid, and by 
the formation of the figures characteristic of double-refracting crys- 
tals between crossed Nicol prisms in converging light. 

1 Such a substance is called monotropic. For a discussion of this phenomenon, 
see Findlay, "The Phase Rule," 4th Ed. (10,14), 46-9; and Holleman, "Organic 
Chemistry," 4th Ed. (1914), 430; and Lehmann, " Molecularphysik" (1888), 
Vol. I, 193-213, 291-309, 687-695. The following common substances exist in 
these two modifications: benzophenone, />-tolyl-phenyl-ketone, $8-dibrom-pro- 
pionic acid, mono-chloracctic acid, acetanilidc, tt-triphenyl-guanidine, m-chlor- 
nitrobenzcne, />-nitrophenol, diphenyl-naphthyl-methane,triphenylmethane, penta- 
methyl-leucaniline, styphnic acid, w-dinitro-benzene, resorcinol, hydroquinone, 
trinitro-w-crcsol, phthalic acid, stilbcne-dichloride, benzoin, mandelic acid, cin- 
namic acid, carbostyril, mercury-diphenyl, limonene-tetrabromide, etc. 

2 See Findlay, "The Phase Rule," 4th Ed. (1914), 208-11; Holleman, "Organic 
Chemistry," 4th Ed. (1914), 431-3; and Sidgwick, "The Organic Chemistry of 
Nitrogen," (1910), 118. 

3 For discussion see Findlay, 'The Phase Rule," 4th Ed. (1914), 55-8; and 
Holleman, "Organic Chemistry," 4th Ed. (1914), 408. Cholesteryl benzoate 
melts to a milky liquid at 145.5 an( l to a c ^ ear liquid at 178.5. Azoxyanisole, 
azoxyphenetolc, and ^-methoxy-cinnamic acid also show a similar behavior. 



68 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

QUESTIONS 

1. Discuss some of the errors in the ordinary method of deter- 

mining the melting-point. 

2. Why is it necessary to heat slowly when the temperature is 

near the melting-point? 

3. Why should the substance be powdered? 

4. What objection is there to the use of a rubber band for holding 

the melting-point tube to the thermometer? 

5. What advantage does cone, sulfufic acid have over glycerine 

and cottonseed oil as used in the melting-point apparatus? 
(Compare behavior on heating.) 

6. What bath is used for taking melting-points above 300? 

7. What is the object of adding sometimes a crystal of potassium 

nitrate or sodium persulfate to the cone, sulfuric acid bath? 

8. Given two substances having the same melting-point, if one 

is known, how can you tell whether the other compound 
is identical with the first by means of the melting-point 
determination? Explain. 

9. What advantage has water over cone, sulfuric acid for deter- 

mining low melting-points? (Compare specific heats.) 



Experiment No. 13 

FORMATION OF A TERTIARY ALCOHOL BY MEANS or GRIGNARD'S 

REACTION 

Preparation of Dimethyl-ethyl-carbinol (2-methyl-butanol-2) l 

The success of this experiment depends on the absence of 
water until after the ketone is all added. Therefore the appara- 
tus and substances used must be perfectly dry. Dry the acetone 
with anhydrous potassium carbonate or anhydrous sodium sul- 
fate, the ethyl bromide with calcium chloride, and the " absolute " 
ether with very thin slices of clean sodium in a flask provided with 
a calcium chloride tube. 2 Let them all stand at least overnight. 
Use larger amounts than called for below since some is absorbed 
by the drying agents. The " ether over sodium " or " absolute " 
ether as obtained from the stockroom must be dried again because 
it cannot be kept free from water in the ordinary containers. 
The ordinary ether can be used for this experiment if it is treated 
as follows: Shake it two or three times with different portions 
of a saturated solution of salt in order to remove the alcohol and 
dry first with calcium chloride and then with sodium. 3 If it is 
turbid at the end of the drying, it should be distilled under an- 
hydrous conditions (see Absolute Alcohol, p. 26), and then 
dried again with sodium before use in the experiment. 

1 The Geneva or official nomenclature is outlined in Amer. Chem. Journ., 15 
(1893), 50- 

2 During warm weather a small reflux condenser in addition should be used to 
prevent excessive evaporation of the ether. 

3 Sodium residues : Great care should be exercised in handling the residue of 
sodium. It should not be put into the sink or the waste jar, but should always be 
destroyed by adding it in small pieces to some alcohol or acetone in a beaker, 
waiting until practically all action has ceased with each piece before adding another. 
Then (Care!) pour the solution into the sink, a little at a time. Also rinse the 
flask with alcohol or acetone before adding any water. 

69 



70 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Ether Distillation. Ether must be kept away from flames. 
Its vapor is heavier than air and vecy inflammable, and therefore 
the heating for the distillation must be done with steam or 
warm water. In ether distillation use an Erlenmeyer suction flask 
as a receiver connected as in the Absolute Alcohol experiment, 
p. 27, but with a long rubber tube attached to its outlet tube and 
leading below the level of the desk to carry away the fumes. 
When small quantities are distilled an ordinary flask may be used 
as a receiver and the space between the condenser tube and mouth 
of the flask loosely plugged with cotton to prevent the circulation 
of the vapors. 

Have all necessary connections ready before the experiment 
is started. 

To a 250 cc. flask containing 5 grams of dry magnesium 
turnings attach an addition tube and reflux condenser with inner 
tube dry. 1 Insert a dropping-funnel 2 in the addition tube and 
connect a calcium chloride tube filled half with calcium chloride 
and half with soda lime (to remove carbon dioxide). The soda 
lime should be next to the large open end of the tube. Add 25 
cc. of dry ether to the flask. Place a solution of 30 cc. (44 grams) 
of dry ethyl bromide (twice the theoretical amount required ac- 
cording to the equation) in 15 cc. of dry ether into the bulb 
of the funnel, stopper loosely and let this slowly drop into the 
flask. A vigorous reaction begins after the first small portion has 
been added. Moderate by surrounding the flask with cold water. 
If it does not start spontaneously, warm the flask with the hand 
or add a crystal of iodine. Shake frequently. After the reac- 
tion is well started add 50 cc. of the dry ether direct to the 
mixture by pouring it through the condenser. When practically 
all the magnesium has disappeared cautiously add, with shaking 
and good cooling, a solution of 15 cc. (12 grams) of dry acetone 
and 10 cc. of dry ether from the dropping-funnel. Each drop 
reacts with a hiss and causes a white precipitate which at first 
redissolves but later settles down as a bluish-gray, viscous mass. 

1 See Fig. 3, p. 13. 

2 The connection can sometime . be made with a piece of rubber tubing instead 
of a cork. 



LABORATORY EXPERIMENTS 71 

After the reaction is complete cautiously decompose the 
addition product by adding, from the funnel during about 
thirty minutes, the calculated amount of sulfuric acid l in 140 cc. 
of water. During this treatment place the flask in ice and shake 
frequently. A flocculent white precipitate is formed at first 
but is later dissolved. (?) Separate the ethereal solution which 
contains the product, and dry with fused potassium carbonate. 
Remove the ether by distillation, observing the precautions 
mentioned above, and fractionate the residue in a small distilling 
flask. Since the carbinol is volatile with ether collect the 
distillate in the following fractions: 7o-95, 95-io5, 105- 
110, then redistill each, collecting the portion distilling ioo- 
104 as the sample. Pure dimethyl-ethyl-carbinol boils at 102 
and has a specific gravity of 0.8069 a ^ 25. Yield, 40 per cent 
of the theory. 

Test the first runnings of the distillate for unsaturated com- 
pounds with bromine in carbon tetrachloride, and with dilute 
potassium permanganate. (?) 

NOTE 

Magnesium turnings for use in the Grignard reaction must be 
prepared fresh or kept in a bottle whose cork has been covered with 
melted paraffin to prevent the entrance of moisture. Otherwise 
the magnesium becomes coated with the hydroxide, etc., and does 
not react well. 

REFERENCES 

Gattermann, "Practical Methods of Organic Chemistry," 3d 
Amer. Ed., 350-4; Wren, "The Organometallic Compounds of Zinc 
and Magnesium" (Van Nostrand, 1913), 1-36, 72-9; Nelson ana 
Evans, "Electromotive force developed in cells containing non- 
queous liquids," Journ. Amer. Chem. Soc., 39 (1917), 82. 

QUESTIONS 

1. How does moisture cause trouble in this experiment? 

2. Why is absence of water unimportant after the ketone 

has been added? 

1 Cone, sulphuric acid of sp. gr. 1.84 contains approximately 96% H 2 SO.j 
by weight. Make sure of your equation before making this calculation. 



72 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

3. Why isn't ordinary ether used and dried directly with 

calcium chloride as in the case of the acetone? 

4. Why cannot the acetone be dried with metallic sodium? 

5. What other solvent besides ether can be used for this experi- 

ment? Why? 

6. What reactions take place when ether, magnesium, and 

ethyl bromide are brought together? 

7. Why is the flask containing this reaction mixture kept in 

cold water? 

8. Why is the acetone added cautiously? 

9. Can the acetone be added directly with the ethyl bromide 

to the ether and magnesium mixture? (Compare Davies 
and Kipping, Jour. Chem. Soc., 99 (1911), 296-301.) 

10. What would happen if carbon dioxide came in contact 

with the Grignard reagent? 

11. Is the magnesium oxidized or reduced in the experiment? 

12. What would be formed if only water was added at the end of 

the reaction? 

13. What is the purpose of adding acid? Is it absolutely 

necessary? 

14. Could cone. H2SO4 be used in place of dilute acid? 

15. What causes the bubbling that often occurs after all the 

dilute acid has been added? 

1 6. What might be some of the impurities in the crude tertiary 

alcohol? (Compare the properties of the "first iimnings" 
of the distillate.) 

17. Explain what is meant by the term " volatile with ether." 

(Compare fractionation of liquids which mix in all pro- 
portions.) 

18. Why use a small distilling flask in the redistillation of 

dimethyl-ethyl-carbinol? 

19. How does this pentyl (amyl) alcohol differ from the isomyl 

alcohol of commerce? 

20. The amount of ethyl bromide (30 cc.) is twice the amount 

required by the theoretical equation. Why is it necessary 
to use an excess? 



Experiment No. 14 

REDUCTION OF A KETONE TO A SECONDARY ALCOHOL (SODIUM 
ALCOHOL REDUCTION) 

Preparation of Methyl-phenyl-carbinol from Acetophenone 
(Methyl-phenyl-ketone) 

Dissolve 10 grams (10 cc.) of acetophenone in 125 cc. of al- 
'cohol in a 500-00. flask, with an addition tube attached and a 
reflux condenser connected with the side tube. Prepare 10 
grams of clean metallic sodium 1 cut in strips narrow enough 
to slip through the vertical tube easily. Add these strips to the 
alcoholic olution through the vertical tube a few at a time and 
let the reaction abate somewhat before the addition of others. 
The reduction should be strong and the alcoholic solution should 
boil vigorously, but at the same time the reaction must be kept 
in hand. 

When all the sodium has dissolved, distill off as much as pos- 
sible of the alcohol, in vacua. Since it is difficult to transfer the 
reaction-mixture, which is very viscous, and since there is a great 
deal of foaming during the distillation, the original flask is used 
for this first distil ation instead of the Claisen flask described in 
the accompanying d rections 'or vacuum distillation, Expt. 15, 
p. 76. Slant the flask in order to allow the foam to " break " 
against the walls and not pass out into the distillate. Connect 
it with a bent tube leading into a distilling-flask which acts as a 
receiver (Compare Fig. u). The receiver need not be cooled 
in this case; let the alcohol vapors pass through uncondensed. 
The receiver is used to catch any of the product which some- 
times distills or goes over with some foam. Heat the main flask 

1 Use a common knife or pen-knife to cut the sodium and dip the blade 
frequently into the kerosene with which the sodium is covered Return all resi- 
dues to the original bottle or destroy them with alcohol, as mentioned under 
Dimethyl-ethyl-carbinol, p. 69. 

73 



74 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

with water kept at 5o-6o, and frequently shake the flask 
somewhat to change the surface of the mixture and thus permit 
rapid vaporization. The distillation requires from one to two 
hours. As it progresses the mixture becomes a darker brown, 
and pasty. 

When practically all the alcohol is distilled over add 50 cc. 
of water and then exactly neutralize the solution with acetic 
acid. Distill off the remaining alcohol in vacua from the same 
flask and in the same manner as before. 

Ether Extraction. Transfer the residue to a separatory 
funnel with the aid of water and a little ether, and extract it with 
ether as follows: Add about 30 cc. of ether (and if necessary 
enough water to dissolve any precipitate), stopper securely, 
invert the funnel, holding the stopper in with one hand and plac- 
ing the thumb of the other hand on the handle of the stop-cock 
and the first two fingers on the other side of the stem and shake. 
While it is still inverted open the stop-cock to release the pres- 
sure l within the funnel. Clo e the stop-cock and shake again, 
frequently releasing the pressure. Turn the funnel right side 
up, support it in a ring, allow to settle, draw off the aqueous 
layer into a beaker, and pour the ethereal solution from the top 
of the funnel into a dry Erlenmeyer flask. Return the aqueous 
layer to the funnel, repeat the extraction with about the same 
amount of ether, and add the ethereal solution to the first por- 
tion in the Erlenmeyer flask. 

If some of the product was distilled over into the receiving 
flask, the material thus collected should be extracted with ether, 
provided it contains practical'y no alcohol, and added to the 
main ethereal solution. If it contains much alcohol it cannot 
very well be extracted with ether (?), and the alcohol must be 
evaporated off before extraction. 

If the main ether extract is acid to litmus, neutralize it by 
shaking with a solution of sodium carbonate. 

Dry the ethereal soluton with fused potassium carbonate, 
transfer it to a Claisen distilling-flask, remove the ether by 

1 In this laboratory there are two cases on record where the separatory funnel 
exploded on account of carelessness in disregarding this procedure. 



LABORATORY EXPERIMENTS 75 

distillation under the usual conditions and then distill the residue 
in vacua, in accordance with the directions given in Expt. 15, 
following this. Some ether will pass over first, the temperature 
then rises and the carbinol distills. It boils at 118 at 40 mm., 
106 at 21 mm., and 98 at 15 mm. At atmospheric pressure, 
it boils with partia decomposition at about 202. The yield 
is about 40 per cent of the theoretical amount. 

REFERENCES FOR ETHER EXTRACTION 

Walker, " Introduction to Physical Chemistry," 7th Ed. (1913), 
59-61; Alex. Smith, " Introduction to Inorganic Chemistry," jd 
Ed. (1917), 189. 

QUESTIONS 

1. Why is alcohol used in this experiment? 

2. Is all the alcohol used up during the reaction? 

3. What becomes of the sodium ethoxide? 

4. Point out what is reduced and what is oxidized. 

5. Is the methyl-phenyl-carbinol formed acted upon by 

sodium? 

6. What other organic compound is likely to be formed? 

7. Is this a " higher " or " lower " reduction product of the 

ketone? 

8. Why is sodium used instead of some other metal like zinc? 

9. Why does sodium react with alcohol while zinc does not? 

10. Where does the " remaining alcohol " come from? 

11. How could you calculate how much of this " remaining 

alcohol " there would be? 

12. Why is it necessary to distill off this alcohol before extracting 

with ether? 

13. Why is the ethereal solution poured from the top of the sep- 

aratory funnel? 

14. Discuss the extraction of aqueous solutions and mixtures 

of organic substances with immiscible liquids, such as 
ether, chloroform, benzene, etc. 

15. What is meant by the Coefficient of Partition or Distribu- 

tion? (See references above.) 

16. Why is it necessary to distill in a vacuum? 

17. What is the boiling-point of acetophenone? 

18. How could the presence of any unchanged acetophenone 

be shown in the product? 

19. Is the methyl-phenyl-carbinol as prepared in the laboratory 

optically active? Explain. 



Experiment No. 15 
Distillation in vacua or under Diminished Pressure 

Distillation in vacuo or under diminished pressure is always 
resorted to if the compound decomposes when heated at atmos- 
pheric pressure, but is volatile without decomposition at lower 
pressures. The apparatus employed is indicated diagrammatic- 
ally in Fig. ii. A Claisen distilling-flask is used since it has a 
side arm which helps to prevent any liquid from being sprayed 
up into the outlet tube if the liquid should bump violently, and 
since tighter joints can be obtained by connecting the ther- 
mometer and the capillary extension tube with heavy rubber 
tubing outside than when rubber stoppers are used. Attach 
an ordinary distilling-flask as the receiver with a rubber stopper, 
making certain that the outlet tube of the Claisen flask projects 
into the bulb of the receiver in order that the vapors of the dis- 
tillate may not be carried off by the suction. During the dis- 
tillation cool it with running water. 1 Support both flasks with 
clamps. If the temperature of the distillate under the diminished 
pressure exceeds 160 the rubber stopper in the receiver should 
be changed for a good cork stopper. Rubber stoppers soften and 
gradually melt above this temperature. A good cork stopper 
can sometimes be made air-tight by coating it with collodion 
after the apparatus has been fitted up. Connect the delivery 
tube of the receiver by means of rubber " pressure " tubing to a 
manometer and a water pump. By using glass tubing and short 
rubber connections only a small amount of the expensive " pres- 
sure " tubing is necessary. All glass connecting tubing should 
have smooth, rounded ends. 

1 The cooling is made more efficient if a piece of cloth is wrapped around the 
bulb of the receiving flask. 

76 



LABORATORY EXPERIMENTS 



77 




78 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

A good water pump will give a pressure in the apparatus 
as low as the vapor tension of the water at its particular tem- 
perature. In winter when the temperature of the water may be 
8, at which the vapor tension of the water is 7.99 mm., the 
pressure within the apparatus may approach 8 mm., but in sum- 
mer when the temperature of the water may be as high as 23 
a pressure cannot be obtained lower than 21 mm., which is the 
vapor tension of the water at that temperature. 1 

The general connections for vacuum distillation are made 
as follows: Outlet tube of the receiver to an Erlenmeyer suc- 
tion ftask and the latter to the water pump and the manometer. 
The tube connecting the suction flask with the pump should 
extend to the bottom of the flask in order that any water which 
may come over on account of unequal pressure in the water 
main will be sucked right out as soon as the greater water pres- 
sure returns. A three-holed rubber stopper is used in the mouth 
of the suction flask. This provides for the tube to the pump, 
just mentioned, for the tube connecting the manometer, and for 
a glass stop-cock which is used for equalizing the pressure when 
necessary (or this glass stop-cock may be placed between the 
receiver and the suction flask). A " vacuum " valve 2 may be 
placed just before the pump. Instead of using a distilling- 
flask as the receiver it is often convenient for small amounts 
of high-boiling liquids or solids to use a " suction " test-tube 
a test-tube with a side outlet tube. In some cases, a sample 
tube can be placed inside, and then it will not be necessary to 
transfer the distillate. 

In order to prevent bumping the vapor phase is introduced 

1 For pressures lower than these, a good oil pump must be used. Then it is 
possible to go down to o.i mm. 

A table of the vapor pressure (tension) of water at different temperatures is 
given on p. 301. 

2 Not shown in the figure. A "vacuum" valve consists of a glass tube bent 
in the form of a narrow inverted U with elongations at the end ; for connecting 
purposes. One arm contains a free-moving hollow glass plunger which is ground 
at one end to fit into a corresponding ground glass scat formed by a constriction. 
When the pressure suddenly changes the plunger moves up into the ground seat 
and closes the tube automatically, and moves out again when the pressure is 
reversed. It serves to keep water from being drawn into the apparatus. 



LABORATORY EXPERIMENTS 79 

by using pieces of porous tiling 1 in the liquid, or better by 
passing a rapid continuous stream of tiny air bubbles through 
the liquid (see discussion in note 2, p. 18, of the Boiling-point 
experiment). An ordinary glass tube is drawn out into a fine 
capillary, and cut off at the proper length. To the wide end is 
attached a short piece of rubber tubing with a screw clamp at 
its upper end to regulate the bubbling. 2 Sometimes the capillary 
can be made so fine that no other regulation will be necessary. 
A slight drawback to this method is that it introduces an error 
in the boiling-point, as the pressure registered when air is 
present will be the sum of the partial pressures of the vapor 
and of the air. 

The distilling-flask should not be more than one-third full. It 
is heated by means of a water or an oil-bath, 3 according to the 
temperature required. Good results are obtained by immersing 
the bulb of the flask at least two-thirds into the bath. The vapor 
is not superheated so much as under ordinary conditions on 
account of the rarefaction of the vapor and less heat conduct- 
ance. A thermometer is kept in the oil and the temperature 
of the oil should not ordinarily be more than 2o-3O higher 
than the temperature at which the liquid in the flask distills. 
The heating is not begun until the apparatus is exhausted. 
Sometimes it is necessary to prevent radiation by wrapping 
filter or asbestos paper around the neck of the flask below the 
outlet tube. 

1 The porous tiling loses its efficiency within a short time, probably because 
the air is given up more rapidly under the reduced pressure. 

2 If an ordinary distilling-flask is used instead of the Claisen distilling-flask, 
and if there is not space enough for both thermometer and the glass bubbling 
tube in the neck, the thermometer may be placed within the tube and a one-holed 
stopper used. 

3 Rape-seed oil is good to use. Paraffin or paraffin oil smokes a great deal. 
The rape-seed oil also smokes somewhat at first and gives off a pungent odor, 
but after two or three heatings it does not smoke so much. It can be carried up 
to about 300. A metal bath has the advantage that it does not smoke and is not 
liable to catch fire, but it is solid at ordinary temperatures. Following are alloys 
which can be used for low-melting baths: Wood's metal, 1-2 parts of cadmium, 
2 of tin, and 7-8 of bismuth, melts at 71; Rose's metal, 2 parts of bismuth, i of 
lead, and i of tin, melts at 95; an alloy of i part of lead and 2 of bismuth, melts 
at 120. If the flask which is heated in such metal baths is coated with graphite 
the metal will not stick to the glass. 



80 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

It is best to test the apparatus before putting in the substance 
in order to determine whether the glass is perfect and the joints 
are tight. In this way a loss of material may often be avoided. 

When carrying out a vacuum distillation it is advisable to 
protect the eyes with goggles, or use a glass screen. 

At the end of the distillation the stop-cock should be grad- 
ually opened before the water is turned off. If the stop-cock 
is used between the receiver and the suction flask, the stopper 
itself is gradually and carefully removed. This allows the mer- 
cury column to settle slowly and also prevents water vapor from 
being sucked into the apparatus. 

The Manometer. The manometer consists of a glass tube 
bent in such a way as to hold a column of mercury, a scale, 
and a stand for a support, as shown in the figure. The short 
length of the glass tube should be about 50 cm. long and the 
longer length 85 cm. The lower bend can be made by one 
heating in a smoky flame. After the mercury has been poured 
in, 1 insert a plug of cotton to keep out foreign matter and place 
a small test-tube over it. By slanting the manometer when the 
mercury is added any air bubbles will come out readily, especially 
if the tube is tapped. The glass tube should be dry and free from 
dust, grease, etc. If the mercury does not run free from bubbles 
wash the tube with alcohol and ether and remove the adhering 
ether with a current of air. The column of mercury is of such a 
height that when the apparatus is exhausted the lower and upper 
limits of the mercury will be opposite some point on the scales 
described below. The glass tube is connected with the suction 
flask. 

To Make the Scale. Select any point, X, not less than 
38 cm. above the lowest bend in the glass tubing, and attach 
narrow strips of paper (Y and Z) near the top and the bottom of 
the stand in the positions shown. Measuring from the point A 
mark on the papers numbers showing 28 to 38 cm. up and down 
respectively. Ruled centimeter paper is very convenient, and 
when this is used it should not be attached until a definite 
point opposite a centimeter line has been located. 

1 Use a small funnel connected by means of rubber tubing to the manometer tube. 



LABORATORY EXPERIMENTS 81 

Instead of these scales a meter stick can be fastened to the 
stand and the different heights read directly. 

To Calculate the Pressure within the Apparatus. Add the 
figures on the lower and upper scales opposite the top of the 
mercury meniscus l in each case and subtract the sum of these 
numbers from the barometric reading. Record both the boiling- 
point and the pressure, for example b. p. 22 145. The tem- 
perature of the bath should also be recorded for reference. 

It is not always possible to obtain exactly the same pressure 
at which the boiling-point is given in the text. However, the 
difference in boiling-points at the given pressure and the pressure 
actually used can be estimated. The distillate is, of course, 
always collected while the temperature (and pressure) remains 
constant. * 

There is no set rule or exact method of calculation for finding 
the boiling-point under diminished pressure when only the 
boiling-point at 760 mm. is known. A few general hints may be 
given. A substance that boils around 100 at 760 mm. will 
boil about 60 lower at 25 mm., and one that boils around 200 
at 760 mm. will boil about 8o-ioo lower at 25 mm. The 
variation in the boiling-point becomes greater for each degree 
at the lower pressure, and is very marked as the pressure drops 
below 3 or 4 mm. 

NOTES 

1. Purification of mercury: If the mercury is wet or dirty it can be 
purified by running it through a dry filter paper which has a pin hole 
in the bottom. The impurities stick to the paper, which also absorbs 
the moisture. Several treatments may be necessary with clean filters 
each time. 

2. If the water pump does not "catch," and the water runs out 
straight without causing proper suction, hold the hand close to the 
bottom of the pump while the water is turned on and cause a slight 
back pressure until the suction is all right. 

3. Never use an ordinary flat-bottomed flask in the apparatus 
for vacuum distillation. Explain. 

1 Tap the glass tubing before taking the reading in order to bring the mercury 
to rest and overcome the "lag." 



82 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

4. Sometimes for more complete cooling a water condenser must 
be placed between the distilling-flask and the receiver. 

5. An apparatus for collecting fractions without interrupting the 
distillation is described by M. T. Bogert, Journ. Ind. \and Eng. 
Chem., 7 (191 sX 785-6. 

6. If water should splash into the oil, the distillation must be 
stopped and the wet oil replaced with fresh oil. If this happens 
while the oil is hot it will foam very much and great care must be 
used to prevent any of the hot oil from getting on your hands, etc. 
Oil with even a very small amount of water in it is useless. 

QUESTIONS 

1. In " vacuum distillation " how is bumping avoided? 

2. Why should the outlet tube of the distilling-flask extend 

into the bulb of the receiver? 

3. Why should the distilling-flask be not more than one- third 

full? 

4. Why is the stop-cock opened before the water is turned off? 

5. Why is the tube from the suction flask to the pump run 

down to the bottom of the suction flask? 

6. What advantages has a Claisen flask in distillation in 

vacua? 

7. Why should an ordinary flat-bottomed flask never be used 

in the apparatus for vacuum distillation? 

8. How low a pressure can be obtained with a water pump? 

9. Why is it not necessary to have an absolutely definite 

volume of mercury in the tube? 

10. Do air bubbles along the walls make any difference? 

11. Does the mercury drop exactly as far as it rises? 

12. Which reading on the barometer should you use for calcula- 

ting the pressure within the apparatus, the " corrected " 
or " uncorrected "? 



Experiment No. 16 

OXIDATION OF A PRIMARY ALCOHOL TO AN ALDEHYDE 
Preparation of a Solution of Acetaldehyde 

In this experiment ethyl alcohol is oxidized to acetaldehyde 
by means of sodium dichromate in dilute sulfuric acid solution. 
Since it is difficult to separate the acetaldehyde, which boils at 
21, from the impurities by fractionation, the crude acetaldehyde 
is usually absorbed in ether and converted into the crystalline 
aldehyde ammonia, which is easily purified, and then used foi 
making pure acetaldehyde. This is a long process, however, and 
requires elaborate apparatus, as described in Expt. 17. 

For making a crude product which can be used in the alde- 
hyde tests, proceed as follows: 

Attach a dropping-funnel to a 25o-cc. distilling-flask con- 
nected with a long water condenser, and arrange a receiver set 
in ice. On account of its low boiling-point care must be exer- 
cised in catching the distillate. A small Erlenmeyer flask makes 
a good receiver. The end of the condenser should extend into 
it as far as possible and the flask should be entirely surrounded 
by ice. Add a mixture of 20 cc. of cone, sulfuric acid and 50 cc. 
of water. Fill the dropping-funnel with a solution of 20 grains of 
sodium dichromate in 30 cc. of water and 25 cc. of alcohol, and 
during the course of about fifteen to twenty minutes allow this 
to drop slowly into the flask. Heat the mixture to gentle boiling 
with a very small flame. After all the solution has been added 
continue the gentle heating for several minutes. Redistill very 
slowly, collecting the portion boiling between 20 and 45 in an 
ice-cooled receiver. Acetaldehyde boils at 21. The product 
(which need not be handed in) contains some water, but can be 
used in the experiments entitled " Tests for Aldehydes," Expt. 

83 



84 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

19, p. 91. For study, use the questions given under the prepara- 
tion of acetaldehyde from aldehyde ammonia, Expt. No. 18, p. 90. 

NOTE 

This experiment and the tests which follow should if possible be 
carried out during one laboratory period. Otherwise extra pre- 
cautions must be taken to keep the solution of the aldehyde properly 
stoppered and cooled. 



Experiment No. 17 

OXIDATION OF A PRIMARY ALCOHOL TO AN ALDEHYDE 
The Preparation of Acetaldehyde Ammonia 

In this experiment ethyl alcohol is oxidized to acetaldehyde 
by means of sodium dichromate in dilute sulfuric acid solution. 
Since it is difficult to separate the acetaldehyde, which boils at 
21, from the impurities by fractionation, the crude acetaldehyde 
is absorbed in ether and converted into the crystalline aldehyde 
ammonia, which is easily purified, and then used for preparing 
pure acetaldehyde. 

Set up the following apparatus and have it ready to start the 
experiment at the beginning of the laboratory period. If the 
experiment cannot be completed in one period, it must at least be 
continued until the aldehyde has all been absorbed in ether 
(one hour) which solution can then be set aside in the icebox 
in a well-stoppered bottle. 

To a 500 cc. flask attach an addition tube (Fig. 3, p. 13), 
insert a dropping-funnel (Fig. 6, p. 36), and connect the side 
arm with a long slanting reflux condenser (60 cm.). Through 
a cork in the upper end of the condenser attach a bent tube and 
connect this with a 100 cc. pipette leading into a 250 cc. wide- 
mouthed bottle (with a vent) set in an ice mixture. Place a 
thermometer inside the inner tube of the condenser and support 
it with a thread held fast by the cork stopper at the upper end. 
The bulb of the thermometer should be as near the center of the 
condenser as possible. Insert another thermometer through the 
stopper at the upper end in order that the temperature of the 
issuing vapors may be noted. 1 Use good corks and make 

1 A second addition tube can be used here also if desired. 
85 



86 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

tight connections throughout. Rubber stoppers may be used 
with advantage. 

Into the bottle surrounded by ice pour 100 cc. of anhydrous 
ether. The pipette should open about i cm. below the surface 
of the ether. Add a mixture of 17 cc. of cone, sulfuric acid and 
75 cc. of water to the flask, and during the course of thirty 
minutes allow a solution of 35 grams of sodium dichromate 
in 60 cc. of water and 50 cc. of alcohol to drop in slowly. During 
this time heat the solution to gentle boiling, and allow the 
water to run very slowly through the condenser. Regulate 
the heat and water flow so that the temperature indicated by 
the thermometer in the condenser does not register higher than 
45. (What is the lowest temperature limit? 1 Why must a 
large flame not be used?) After all the mixture has been added 
continue the heating with the same precautions for an additional 
thirty minutes. If the ether solution at any time should rise 
high in the pipette, add a little more of the solution, or if this 
has all been added simply open the stop-cock of the dropping- 
funnel momentarily. All the aldehyde has been driven over 
when its pungent odor is not very strong in the funnel opened 
for the test. 

When the apparatus is disconnected note the most pronounced 
odor from the mixture in the flask. To what is this due? How 
can you account for it? 

Through a wide tube, such as the large part of a calcium 
chloride tube or an adapter, or a funnel, pass a stream of an- 
hydrous ammonia from a cylinder into the ether solution con- 
tained in the wide-mouthed bottle packed in ice and salt near 
the draft pipe. The solution will be saturated in about five 
minutes. Filter off the white crystals of aldehyde ammonia with 
suction and dry them until all the ether has completely evapo- 
rated. This can be done conveniently in a vacuum desiccator. 
The aldehyde ammonia is somewhat soluble in ether and a second 
crop of crystals can be obtained by concentrating the mother 



1 In wintertime warm water should be added to the condenser to bring the 
temperature within the proper limits. 



LABORATORY EXPERIMENTS 87 

liquor. Determine the melting-point. Yield, 13 grams. 1 The 
aldehyde ammonia often becomes yellow and brown on standing 
and loses its crystalline character, probably due to slow " resin- 
ification." For this reason the product should not be allowed 
to remain in the desiccator more than a day. This chemical 
change can be noted by the lowering of the melting-point. 

NOTES 

1. In case an addition tube is not at hand, use a two-holed stopper 
through which pass the stem of the dropping-funnel and the small 
end of an adapter. The condenser is then connected with the adapter. 

2. If an ammonia cylinder is not available, the dry ammonia 
gas can be obtained by boiling the ordinary cone, ammonium hydrox- 
ide solution, sp. gr. 0.90, and passing the vapors through a drying 
tower containing calcium oxide, care being taken that a wide tower 
is used. 

3. Vacuum desiccator. A vacuum desiccator is like an ordinary 
desiccator, but has as top-cock on a ground-in stopper in the cover. 
Put some calcium chloride or cone, sulfuric acid in the bottom and 
place the watch glass containing the substance on a support, such as a 
perforated porcelain disk or a wire gauze, across the constricted part 
of the desiccator. Grease the stop-cock, and the other ground surfaces. 
Attach the outlet to the suction with a heavy rubber tube, open the 
stop-cock and evacuate. 15-30 minutes usually suffices. Close the 
stop-cock and then remove the rubber tube before shutting off the 
suction (?). When ready to open the desiccator turn the stop-cock 
just enough to let in the air slowly, otherwise the rush of air may 
blow the dry particles about. 

It is well to insert a stout empty bottle in the connection between 
the desiccator and the pump. Then if there is any back pressure 
and the water begins to flow back it will be caught in the bottle and 
you will have time to disconnect before it reaches the desiccator. 

Never go away and allow the stop-cock to remain open with the 
suction on, especially when a water-pump is used. The change in 
water pressure may cause the water to be drawn in and flood the 
desiccator. 

1 This amount is too bulky for the usual preparation bottle. Hand in a 
sample, stating the total yield on the label, and use the major portion for the 
preparation of acetaldehyde itself in the next experiment. 



88 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Liquids will evaporate about six to seven times faster in a vacuum 
desiccator than in an Ordinary desiccator, as shown recently by Mr. 
W. E. Morgan. 

The efficiency of the conventional vacuum desiccator can be 
increased if it is provided with a second inlet tube, with stop-cock 
attached, in the lower part of the desiccator. While the suction is 
on, allow air, which is thoroughly dried by passage through some of 
the same kind of drying agent used within the desiccator, to enter 
very slowly through this inlet tube. 

QUESTIONS 

1. Write equations for all the chemical changes involved in the 

formation of acetic aldehyde from ethyl alcohol by this 
method. 

2. Point out in the above reactions what is oxidized and what 

is reduced. 

3. Why cannot a simple water solution of sodium dichromate 

be used instead of one that has been acidified with sul- 
furic acid? 

4. What causes the green coloration? (Compare Mellor, 

"Modern Inorganic Chemistry" (1912), 652.) 

5. Could hydrochloric or acetic acid be used in place of sul- 

furic acid? 

6. Why is a dropping-funnel necessary? Why not add the 

mixture of dichromate and alcohol all at one time? 

7. Why not omit heating the mixture in the reaction flask until 

after the alcohol and the dichromate has all been added? 

8. Why is the condenser attached to the reaction flask held in 

a slanting position? 

9. Why is it important to keep the temperature of the condenser 

at about 45? 

10. Why is it necessary to absorb the acetic aldehyde in anhy- 

drous ether? Why is water not used in place of ether? 
Alcohol? 

11. Why is it necessary to keep the ethereal solution of the 

aldehyde cold? 

12. How does anhydrous ammonia react with acetic aldehyde? 

Write equation. 

13. Do all aldehydes react in a similar way when treated with 

anhydrous ammonia? Compare formaldehyde and benz- 
aldehyde. 

14. How does water react with formaldehyde? 



LABORATORY EXPERIMENTS 89 

15. Could aqueous ammonia be used in place of tne anhydrous 

ammonia? 

1 6. Why is a wide tube used to pass the ammonia gas into the 

ethereal solution? 

17. Explain how a mixture of ice and salt is colder than ice alone. 

1 8. What advantage does a vacuum desiccator have over an 

ordinary desiccator for drying these crystals? 

19. What impurities are liable to contaminate the crystals of 

aldehyde ammonia? Name four and account for them. 

20. Since the object of making the aldehyde ammonia is not only 

to show the formation of the addition product but also to 
obtain pure acetaldehyde, why not make the pure acetalde- 
hyde directly by simply catching the main distillate in a 
flask Jn a freezing-mixture and then fractionating this? 



Experiment No. 18 
The Preparation of Acetaldehyde from Aldehyde Ammonia 

From the aldehyde ammonia (which should be entirely free 
from ether) prepared in the preceding experiment prepare acet- 
aldehyde as follows: Provide a distilling-flask with a dropping- 
funnel, connect with a condenser and attach to the latter a tube 
leading to the bottom of a second distilling-flask which is set in a 
mixture of ice and salt. Dissolve 10 grams of aldehyde ammonia 
in 25 cc. of water and allow this to drop into a solution of 8 cc. 
of cone, sulfuric acid in 20 cc. of water in the distilling-flask 
heated with boiling water. Dry the distillate with calcium 
chloride in the flask in which it was collected by shaking for 
a few minutes, and then distill from this same flask without 
removing the calcium chloride, using the precautions noted above. 
Pure acetaldehyde boils at 20.8 cor. Use the product in the 
following experiments. (Keep the product in a well-stoppered 
bottle in the ice-box if it is not used on the same day it is made.) 

QUESTIONS 

1. Write all equations for reactions involved in the formation 

of the aldehyde from its aldehyde ammonia. 

2. Why should the aldehyde ammonia used be entirely free from 

ether? 

3. Why is the aldehyde ammonia dissolved in water before 

being added to the dilute sulfuric acid? 

4. Why should the end of the condenser be extended to the 

bottom of a small distilling flask? 

5. Why is this distilling flask surrounded by a freezing mixture? 

6. Why is it necessary to redistill the aldehyde? 

7. Could any other drying agent besides calcium chloride be 

used for drying the acetic aldehyde? 

8. What advantage has the porous calcium chloride over fused 

stick calcium chloride in this case? 

9. Why is the drying agent not removed before the distillation 

in this case while in practically all other experiments the 
drying agent is removed before the distillation? 

on % 



Experiment No. 19 
Tests for Aldehydes 

1. Silver-mirror test. Make an ammoniacal solution of 
silver nitrate by treating 4 cc. of N/io silver nitrate with $N 
ammonium hydroxide drop by drop until the precipitate (?) 
which is first formed just redissolves. Add a single drop of the 
aldehyde, quickly mix by shaking, and set the tube in the rack. 
A deposit of metallic silver will begin to form at once and soon 
makes a beautiful mirror. If the test-tube is not perfectly 
clean only a black precipitate of silver will be obtained. If 
necessary, clean the tube with boiling sodium hydroxide solu- 
tion. \ 

Sometimes a very small amount of dilute sodium hydroxide 
solution must be added in order to get the reduction. Com- 
pare Benzaldehyde experiment, p. 182. A mixture of sodium 
hydroxide and silver nitrate constitutes Tollens' reagent for 
aldehydes. 

Do not heat the silver solution or let it stand for a long 
time, since explosive compounds are formed. See Smith, " In- 
org. Chem.," p. 753; Alfred Tingle, "Ammoniacal Silver oxide 
Solution," Journ. Ind. and En g. Chem., 11 (1919), 379; and E. J. 
Witzemann, ibid., 11 (1919), 893; also, note, 884. 

2. Reduction of Fehling's Solution. Mix 3 cc. of each of the 
two portions of Fehling's Solution (" copper half " and " alka- 
line tartrate half "), and bring the clear, deep blue solution to a 
boil. Note whether a precipitate is formed. If not, add a 
drop of the aldehyde and boil for a minute. A yellow precipitate 
of cuprous hydroxide is generally formed at first and this is 
rapidly converted into bright red cuprous oxide. If the amount 
of reduction is small the cuprous oxide sometimes cannot be seen 
until after the solution has been allowed to stand long enough 
for it to settle out. Or the solution can be filtered. Note the 
odor during the boiling, and compare test 4. 

91 



92 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Fehling's solution is kept in two parts because it gradually 
deteriorates on standing after being mixed. 

3. Polymerization. To a little of the aldehyde add a single 
drop of cone, sulfuric acid on a stirring rod. (Care!) What is 
formed? 

4. Resin Formation. Gently heat a little aldehyde and a 
few drops of a cone, solution of sodium hydroxide. (?) 

5. Schiff's Aldehyde Test. Schiff's aldehyde reagent con- 
sists of a very dilute solution of fuchsine decolorized with sul- 
furous acid. It is also known as " Fuchsine-sulfurous acid 
reagent," and is furnished ready for use by the stockroom. 

Add a drop of the aldehyde to 5 cc. of water and then add 
a drop of the reagent. The development of the original reddish- 
violet color of the fuchsine indicates the presence of an alde- 
hyde. 

Schiff's reagent can be prepared by dissolving 0.2 gram of 
pure fuchsine or rosaniline (in the form of the hydrochloride or 
acetate) in 15 cc. of water and passing in sulfur dioxide until the 
solution is saturated, This requires but a few minutes and 
the solution will be colorless, provided pure rosaniline or its 
salt were used. Then dilute to 200 cc. It should be kept in a 
dark-colored glass-stoppered bottle. If the bottle is not properly 
stoppered the liquid will gradually lose sulfur dioxide and then 
of course the color will return even before any aldehyde is added. 

Do not boil the reagent! Why? What would happen if 
a weakly alkaline substance was added to the reagent? 

The reactions in the Schiff's Aldehyde Test are not completely 
understood. The manner in which the aldehyde removes the 
sulfurous acid is probably similar to the reaction of an aldehyde 
and sodium bisulfite. See Acetone,, p. 98. 

QUESTIONS 

1. Discuss the reactions involved when the acetic aldehyde is 

mixed with ammoniacal silver nitrate. 

2. What is the purpose of the alkali in this test for aldehydes? 

(Stieglitz, " Qualitative Chemical Analysis, " I, 290-2.) 

3. Is it necessary to employ the nitric acid salts for this oxida- 



LABORATORY EXPERIMENTS 93 

tion of the aldehyde, or could silver acetate be used just 
as well? 

4. What advantage does Fehling's solution have over an ordi- 

nary aqueous solution of copper sulfate in testing for 
aldehydes? 

5. How is heating advantageous in the Fehling's solution test 

for aldehydes? 

6. In the polymerization of acetic aldehyde by means of 

sulfuric acid, why is it necessary to add only a trace 
of acid instead of a drop? 

7. Why is it best to cool the aldehyde with a freezing mixture 

before adding the acid? 

8. Write equation and structures in the reactions involved 

in the polymerization of the aldehyde by acid. 

9. Is the above reaction reversible? 

10. Write equations and structures for reactions which take 
place when acetic and formic aldehydes are each treated 
with cone, and with dil. solutions of sodium hydroxide. 



Experiment No. 20 

HYDROLYSIS or METHYLENE DIETHERS (ACETALS) 
Methylal 1 

1. Does its odor resemble that of the ethers? To what 
alcohols are these ethers related? 

2. To 3 drops of methylal in a test-tube add 2 drops of cone, 
sulfuric acid. Heat gently over a small flame until the liquid 
begins to boil, and then allow to cool. What is the white solid 
that is deposited on the walls of the tube? Note the odor of the 
gas evolved. (Care!) Outline the "steps" in the reactions of 
this experiment. 

3. Repeat the above experiment, using dilute sulfuric acid. 
Any white solid formed? Odor? 

4. Try the action of dilute sodium hydroxide solution on 
methylal. (?) 

5. What is an ortho-ester? 2 What is formed when an 
ortho-ester is warmed with an alcoholic solution of potassium 
hydroxide? 

6. Does methylal reduce Fehling's solution, or ammoniacal 
silver nitrate? (See under Acetaldehyde, p. 91.) 

QUESTIONS 

1. Write equations for reactions involved ir\ the chemical 

change produced by the action of cone, sulfuric acid on 
methylal. 

2. What is polymerization? Show by structure how this polym- 

erization of formaldehyde to paraldehyde differs from a 
polymerization like formaldehyde to formose. 

1 Methylal boils at 42. 

2 Richter's "Organische Chemie," n. Auflage (1909), Vol. I, 273, 316. 

94 



LABORATORY EXPERIMENTS 95 

3. What is the structure of the formaldehyde in the water 

solution obtained when dil. sulfuric acid reacts with the 
methylal? 

4. How is methylal formed? Two methods. 

5. Show how it is related to ethers by its behavior when hydro- 

lyzed. 

6. Can diethyl ether be hydrolyzed by sulphuric acid? 

7. Can aqueous alkali cause hydrolysis of methylal or ethyl ether? 

8. Of what alcohol is methylal an ether? Does it exist? Com 

pare chloral hydrate. 



Experiment No. 21 
Formaldehyde 

1. Dissolve 2 drops of methyl alcohol in 3 cc. of water in a 
small test-tube (No. i). Make a compact spiral of fine copper 
wire by winding it around a glass rod. The spiral should be about 
2 cm. long and should have a straight piece about 20 cm. long. 
Oxidize the spiral by moving it rapidly through a Bunsen flame, 
and plunge the red-hot wire into the alcohol solution. Repeat 
this operation several times. 

Pour the solution from the solid particles into another small 
test- tube, and add i drop of a fresh 0.5 per cent solution of re- 
sorcinol. 1 Carefully pour this solution down the sides of a second 
test-tube containing about 5 cc. of cone, sulfuric acid. If the 
second tube is properly inclined the mixture will form a distinct 
layer upon the surface of the acid. 

A red zone, slightly violet in color, will appear, and above the 
zone there will be a light flocculent precipitate. This reaction 
is characteristic of formaldehyde ; other aldehydes do not show 
this behavior. The composition of the colored substance and 
of the precipitate is not well understood. 

(Reprinted with permission from Jones, " A Laboratory Outline of Organic 
Chemistry/' p. 25.) 

2. Evaporate 5 cc. of " formalin " (commercial 40 per cent 
solution of formaldehyde) to dryness on the water-bath, under 
the hood. What is the residue? 

3. Preparation of Hexamethylenetetramine. In a round- 
bottomed flask mix 25 cc. of " formalin " and 15 cc. of cone. 

1 If the resorcinol solution is allowed to stand for some time it gradually develops 
a brownish flocculent precipitate, and then it is worthless for this test. 

96 



LABORATORY EXPERIMENTS 97 

ammonium hydroxide. Insert an inlet tube drawn out to a cap- 
illary at the lower end and opening near the bottom of the flask, 
and an outlet tube connected with a suction flask, stop-cock, 
and water pump, and evaporate approximately to dryness in 
vacuo (compare, Expt. 15, p. 76), over the steam-bath. By 
attaching a piece of rubber tubing with a screw clamp to the 
inlet tube the stream of bubbles can be regulated. Then add 
a second portion of ammonium hydroxide and evaporate again. 

Dissolve out the residue with hot absolute alcohol and filter 
while hot. The hexamethylenetetramine crystallizes out of the 
filtrate in colorless, well-formed rhombohedra. The crystals 
should of course be filtered off before the solution is allowed to 
evaporate to a small bulk since the mother liquor contains a 
considerable amount of by-products as impurities. The sub- 
stance sublimes when heated, and is very soluble in water. 

It is used in medicine, usually under the name of " urotro- 
pine," also for preparing condensation products of phenols 
(Bakelite) , for absorbing poisonous gases, in gas-masks, as an 
" accelerator " (catalyst) in the vulcanization of rubber, etc. 

QUESTIONS 

1. Explain the formation of formaldehyde from methyl alcohol. 

2. What is " formalin "? How prepared commercially? 

3. What is obtained when the " formalin " evaporates to dry- 

ness? 

4. What is trioxymethylene? For what is it used in commerce? 

5. Write the formula proposed for hexamethylenetetramine. 

(Richter's " Organic Chemistry/' trans, by Spielmann, 
Vol. I, p. 211.) 

6. Compare the action of ammonia on formaldehvde, acetalde- 

hyde and benzaldehyde. 



Experiment No. 22 
Acetone 

1. Mix 5 cc. of acetone with 7 cc. of a saturated solution of 
sodium bisulfite. 1 Shake vigorously. Note the heat developed. 
What is the product that separates? How may acetone be 
regenerated from it? How is this reaction used in analysis? 
Do all ketones respond to this test? How does KCN react with 
the bisulfite addition product? 

2. Try the action of the fuchsine-sulfurous acid reagent on 
acetone. (?) 

3. Does acetone reduce Fehling's solution, or an ammoniacal 
solution of silver nitrate? 

*4. Write the structure of dibenzalacetone (dibenzylidene 
acetone). (Compare Perkin and Kipping, " Organic Chemistry," 
p. 456.) How can it be formed? Explain the reaction for its 
preparation. What is its significance in organic analytical chem- 
istry? 

5. How can you prepare iodoform from acetone? Is this 
reaction characteristic of most ketones which contain the 
CH 3 CO group? 

1 The saturated solution of sodium bisulfite is prepared by means of sodium 
hydroxide solution and sulfur dioxide, or by passing sulfur dioxide into a mixture 
of sodium bicarbonate in three parts of water until the solution smells strongly of 
the gas. On long standing unless properly stoppered it is slowly converted into 
the sulfate. This can generally be noticed by loss of the yellowish color of the 
saturated solution and by the presence of a white sediment. It will then no longer 
give the crystalline addition-product with acetone, etc. 

* Need not be studied by students in the "short" course. 



Experiment No. 23 

FORMATION OF A KETONE BY THE OXIDATION OF A SECONDARY 
ALCOHOL AND THE FORMATION OF A KETOXIME 

Preparation of /-Menthone from /-Menthol 

Pour 3 cc. (no more) of cone, sulfuric acid into 40 cc. of 
water and dissolve 5 grams of sodium dichromate in this solution. 
Transfer to a small glass-stoppered bottle, and add 5 grams of 
powdered /-menthol. Shake frequently during the next half 
hour and let stand overnight or longer. When the mixture 
is allowed to stand the solid lumps should be in contact with 
the liquid and not sticking to the walls of the bottle above 
the liquid. These dark-colored, insoluble masses probably con- 
sist of the ester of menthol and chromic acid which is first 
formed, and they gradually disappear, leaving a dark but clear 
solution with the menthone floating as an oil on the surface. 
Extract the mixture in a separatory funnel with about 25 cc. 
of ether. Filter the ether solution into a small weighed beaker 
and evaporate the ether by means of warm water. Support 
an inverted funnel over the beaker and connect with the suction 
to carry away the ether vapors. As soon as the fumes of ether 
are no longer evident as shown by the odor, cool and then 
determine the yield of crude menthone (about 4.5 grams). It is 
somewhat volatile at the ordinary temperature and pressure, 
and therefore it should not be heated too long. 

An excess of sulfuric acid must be avoided since it gradually 
changes the levo-compound into the dextro-variety. Menthone 
is one of the chief constituents of the oil of peppermint. It 
is a colorless liquid boiling at 109 at 36 mm. 

It need not be further purified for the following experiment. 

99 



100 LABORATORY MANUAL OF ORGANIC CHEMISTRY 



Preparation of /-Menthone Oxime from /-Menthone 

Dissolve 2 grams of the crude menthone in three times its 
weight of about 90 per cent alcohol (sp. gr., approximately 0.83) 
in a small beaker (No. oo). Add an amount of powdered hydrox- 
ylamine hydrochloride equal to 1.3 times the theoretical amount 
required by the equation. It will not all dissolve. Then, 
during ten minutes, add in portions with stirring slightly more 
than the theoretical quantity of sodium hydrogen carbonate 
required to neutralize the hydrochloric acid of the first 
salt and free the hydroxylamine. Let stand for thirty minutes 
with occasional stirring. Pour the mixture into 75 cc. of cold 
water and stir vigorously. The oxime separates immediately 
as an oil or a white semi-solid mass which soon solidifies. Cool 
further if necessary to help solidification. Filter with suction. 
Dissolve the product in hot, approximately 50 per cent alcohol, 
50 cc. for each gram, filter while hot if necessary to remove 
any insoluble particles, and set aside for crystallization. Before 
setting aside cover the beaker with a watch glass. After the first 
crop of crystals has been filtered off a second may often be 
obtained by longer standing. White needles of a characteristic 
persisting odor are obtained which melt at 60. The product 
may be dried by letting it stand overnight on a clean porous 
tile covered with a watch glass. In this way their crystalline 
shape is preserved. Yield, 80 per cent of the theory. 

Try the action of a dilute solution of sodium hydroxide on a 
small amount of the oxime. (?) 



NOTES 

1. When the oxime is hydrolyzed with dilute sulfuric acid, the 
angle of rotation of the resulting menthone is changed. 

2. Like most terpene compounds menthone oxime is somewhat 
volatile and therefore should not be left in the open or in a vacuum 
desiccator under diminished pressure for any length of time. 



LABORATORY EXPERIMENTS 101 



QUESTIONS 

1. What becomes of the sodium dichromate? 

2. Write the general structure of the esters of chromic acid. 

3. Why must an excess of sulphuric acid be avoided? 

4. Write the structures of menthone oxime and of hydroxyl- 

amine hydrochloride. 

5. In hydroxylamine hydrochloride why does not the hydro- 

chloric acid neutralize the OH-group? 

6. What is the purpose of the 90 per cent alcohol? Why not use 

95 per cent alcohol? 

7. Why is sodium hydrogen carbonate used? 

8. What other substances could be used in place of the sodium 

hydrogen carbonate? 

9. Is it necessary to use the hydrochloride of hydroxylamine 

or could the free hydroxylamine be added directly? 
Which one reacts? 

10. How can an aldehyde or a ketone be regenerated from the 

oxime? 

11. How do oximes behave towards alkalies? towards boiling 

alcohol and sodium? 

12. Show how oximes can be used in organic analytical chemistry. 

13. Give an experiment which will show that menthone is a 

ketone and not an aldehyde. 

14. How can you prepare menthol from menthone? 

15. What compound is formed when menthone is treated with 

ethyl magnesium iodide and the product hydrolyzed? 

1 6. Give structure and name of acid formed by treatment of 

menthone with HCN and hydrolysis of the cyanhydrin 
compound. 

17. How does menthone behave toward chlorine? 

18. Give the structures of the stero-isomeric forms of menthone 

oxime. 



Experiment No. 24 

FORMATION OF AN ACID CHLORIDE FROM THE ACID 
Preparation of Acetyl Chloride from Acetic Acid 

The apparatus in this experiment consists of a 60 cc. distil- 
ling-flask, provided with a dropping-funnel (Fig. 6, p. 36), and 
attached to a condenser. A second distilling-flask of the same 
capacity tightly connected with the condenser (if a good cork 
connection cannot be made, use a piece of rubber tubing as you 
would a bored cork) serves as the receiver, the outlet tube being 
connected to a calcium chloride tube. 1 The calcium chloride 
in the tube is protected at each end with a plug of glass wool or 
cotton. Since the receiving flask is used later as the distilling- 
flask without transferring the distillate, a thermometer and well- 
fitting cork should be ready before the operation is started. 
All the apparatus must be perfectly dry and the connection should 
be so made that the product does not come in contact with any 
cork or rubber. Use cork stoppers throughout, except as noted 
above. The experiment must be carried out under a hood, or the 
calcium chloride tube connected with a tube opening just 
above the surface of a dilute sodium hydroxide solution contained 
in a bottle and the fumes then led into the draft pipe. The 
acetyl chloride fumes in the air, being decomposed by moisture 
into acetic acid and hydrochloric acid. Care must be exercised in 
handling both reagents and product to keep them from the skin and 
to avoid inhaling the vapors. Acetyl chloride attacks both rubber 
and cork; therefore the apparatus should be disconnected as soon 
as the experiment is completed, and the product should be 

1 Be careful that the calcium chloride tube does not become stopped up dur- 
ing the distillation. 

102 



LABORATORY EXPERIMENTS 103 

kept in a sealed bottle 1 instead of the ordinary specimen 
bottle, although it can be kept for a few days in a glass- 
stoppered bottle. 

Acetyl chloride has a high vapor pressure and therefore good 
corks must be used and the joints made tight, otherwise serious 
losse? will occur. It is best to plan to perform the experiment 
during one laboratory period. 

Add 12 cc. of glacial acetic acid to the distilling-flask, which 
is immersed in cold water in a beaker. Then add slowly from the 
dropping-funnel 7.5 cc. of phosphorus trichloride. When all 
this has been added, mix the liquids by gently shaking the 
flask and allow to stand for about one hour. Then warm the 
water to 4o-5o and continue the heating at this tempera- 
ture for a short time. The liquid, which was homogeneous before 
heating, finally separates into two layers; the upper layer consists 
mainly of the acetyl chloride, and the lower of phosphorous 
acid. Slowly heat the water to boiling until nothing further 
distills. The distillate contained in the same distilling-flask, 
now provided with the thermometer, is carefully redistilled. 
Collect the portion that distills between 52 and 55 in a receiver 
protected with a calcium chloride tube, or with absorbent cotton 
to prevent circulation of air. 

Acetyl chloride is a colorless liquid with a pungent odor, it 
fumes in contact with moist air; b.p. 53, sp.gr. 1.105 at 2O - 

After the yield has been determined perform the following 
test-tube experiments: 

NOTE 

The reactions with acetyl chloride are usually very vigorous. 
Therefore, when carrying out experiments with it care should be 
taken that the test-tube is held in such a position that its contents 
cannot be shot out into the face of the experimenter or of anyone else. 

i. Add a few drops of acetyl chloride to about 3 cc. of water 
in a test-tube. The acetyl chloride sinks to the bottom of the 

1 A thin-walled bottle of soft glass with an extended neck which can be sealed 
off as described at the end of this experiment. 



104 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

tube, but on shaking rapidly dissolves, and heat is evolved. 
What are the products? 

2. To about i cc. of ethyl alcohol add i cc. of acetyl chloride 
drop by drop, cooling the test-tube under the tap. Then add 
an equal volume of water, the tube being cooled as before. Make 
weakly alkaline with sodium carbonate solution and add common 
salt until no more dissolves. What is the pleasant-smelling 
substance that separates out as a mobile layer on the surface of 
the water solution? 

3. To i cc. of aniline add i cc. of acetyl chloride, drop by 
drop. A vigorous reaction occurs, and a solid separates. Cool 
the mixture with water and add about five times its volume of 
water. What substance is formed? What is its trade name? 
Recrystallize by dissolving it in hot water and allowing the 
solution to cool. It is obtained in leaflets which melt at 114 
cor. Determine the melting-point; see Expt. 12, p. 58. 

Write equations for all the above reactions. 

Place the remainder of the product in a sealing tube or bottle 
and seal off the neck by means of a small, blast-lamp flame. On 
account of the volatility of the acetyl chloride the lower part of 
the scaling tube must be kept cool by means of a cloth saturated 
with ice water. Total yield, 12-14 grams. 

NOTE 

For an excellent discussion of the reaction between acetic acid 
and phosphorus trichloride, see Brooks, Journ. Amer. Chem. Soc^ 
34 (1912), 492-9. 

QUESTIONS 

1. Write the equation for this reaction. 

2. When is PC1 5 used to replace OH groups with Cl? 

3. What is the product remaining in the first flask? 

Is the second equation on p. 142 in Gattermann correct? 

4. Account for the HC1 gas. 

5. What two objections are there to the use of PCls in certain 

cases? 

6. Why does acetyl chloride fume in the air? 



LABORATORY EXPERIMENTS 105 

7. Compare acetyl chloride and benzoyl chloride with regard 

to their stability toward water, alkalies, etc. 

8. Compare the physical characteristics of the acyl chlorides 

with the acid from which they are derived. 

9. How can the following classes of compounds be prepared 

from acyl chlorides: esters, amides, acid anhydrides, 

* ke tones and * 3-alcohols? 

10. How is acetyl chloride used for detecting and estimating 

OH groups, and * for distinguishing between i or 2 and 
3 amines? 
*n. What is the Schotten-Baumann reaction? 

12. What is meant by acylation? Acetylation? 

13. What other reagents are used for acetylation? 

14. How can acid chlorides be distinguished chemically from 

alkyl chlorides? 

*i5. How are the sulfone chlorides formed? 

*i6. What is Hinsberg's method of distinguishing between i, 
2 and 3 amines? (Bernthsen, "Organische Chemie," nth 
Ed., 2d par., p. 440; Noyes, " Org. Chem. for the Lab. ," 
2d Ed., p. 160; Clarke, " Org. Anal./' p. 36.) 

17. What is sulfuryl chloride and how formed? Thionyl chlor- 

ide? 

18. Compare the boiling-point of acetyl chloride with that 

of phosphorus trichloride. 

* These questions are not required for study in the "short" course. 



Experiment No. 25 

FORMATION OF AN ESTER FROM THE ALCOHOL AND THE ACID 
Preparation of Ethyl Acetate 

To a small distilling-flask connected with a condenser add 
a mixture of 10 cc. of absolute ethyl alcohol and 12 cc. of cone, 
sulfuric acid. Insert the stem of a dropping-funnel into the neck 
of the flask and let the end reach below the surface of the liquid. 
Heat the flask in an oil-bath. 1 When the temperature of the oil 
reaches 145 allow a mixture of 15 cc. of absolute alcohol and 
15 cc. of glacial acetic acid to drop slowly into the liquid, and 
as soon as the reaction proceeds regularly add the mixture at 
about the same rate at which the products distill. Keep the 
temperature at about 145-! 50 until all the mixture has been 
added. When no more distills over treat the distillate in a beaker 
with a concentrated solution of sodium carbonate until there is 
no further effervescence (?), separate the layers in a separatory 
funnel, and wash the upper layer with about its own volume of 
saturated salt solution. (?) Separate again, dry with anhydrous 
sodium sulfate or fused potassium carbonate, and distill. Ethyl 
acetate boils at 77, its specific gravity is 0.9239 at o, and it is 
soluble i part in 17 parts of water at 17.5. Yield, n grams 
or more. 

NOTE 

The slower the distillation in the first reaction the better the 
yield will be. It will be noticed that practically nothing distills over 
until the temperature has almost reached 145. 

Hydrolysis of an Ester 

In a small flask with reflux condenser attached heat for ten 
minutes 5 cc. of ethyl acetate, 50 cc. of water, and 2 grams of 

1 A shallow iron dish and rape-seed oil are convenient for this purpose. For 
discussion of heating-baths, see foot-note, p. 79. 

106 



LABORATORY EXPERIMENTS 107 

sodium hydroxide. Then distill over about half the liquid. 
Test the distillate for alcohol with potassium dichromate (see 
Expt. 10, "Reactions of Alcohols," p. 54). Empty the remainder 
of the original solution into a porcelain disk and evaporate to 
dryness. Dissolve the residue in water and acidify with sul- 
furic acid. Note the odor. (?) 

How could you test for the acid by a chemical method? 

Outline a procedure for preparing a derivative of the alcohol to 
confirm your qualitative findings (compare methyl ester of 3.5- 
dinitrobenzoic acid, p. 55). 

QUESTIONS 

1. Is it necessary to use absolute alcohol in the preparation 

of ethyl acetate? 

2. Could hydrochloric acid be used in place of cone, sulfuric 

acid? dilute sulfuric acid? Explain. 

3. What would be the effect if some water was added to this 

reaction mixture? or methyl alcohol? or ethylenc? 

4. Would any ethyl acetate be formed without the presence of 

sulfuric acid? If any, how much compared to the yield 
when sulfuric acid is present? 

5. What is the object of keeping the temperature between 145 

and 150? What happens when the temperature is raised? 

6. Would it make any difference if a mixture of 25 cc. of acetic 

acid and 50 cc. of alcohol was run into the reaction flask 
instead of a mixture of 25 cc. of each? 

7. Why is this mixture introduced through a dropping-funnel, 

and led underneath the surface of the solution? 

8. Is the yield of ethyl acetate affected in any way by dis- 

tilling off the ethyl acetate as it is being formed? 

9. Why is the distillate treated with sodium carbonate? Could 

sodium hydroxide solution be used instead? 
10. Why is the ester washed with salt solution instead of water? 
n. Why cannot other drying agents, such as calcium chloride 

and solid potassium hydroxide, be used for the drying of 

the ethyl acetate? 

12. Solve the problems on p. 161, in Gattermann. 

13. Point out all the conditions that are used to give a maximum 

yield of the ester. 

14. What would you expect to happen when methyl acetate is 

heated with dry hydrogen chloride? with an alcoholic 
solution of hydrogen chloride? 



Experiment No. 26 
Hydrolysis (Saponification) of Butter 

Dissolve 2 grams of sodium hydroxide in 2 cc. of water. In a 
porcelain dish, such as a casserole (not a glass beaker. Why?) 
heat 10 grams of butter until it melts, add the concentrated 
solution of sodium hydroxide, and continue \he heating cautiously 
with good stirring until the mixture becomes of a creamy con- 
sistency. Pour it into 15 cc. of water and transfer this solution 
to a distilling-flask. Acidify with 20 cc. of dilute sulfuric acid 
(i part of acid to 4 of water), and distill over about 15 cc. 

a. Test the reaction of the distillate with neutral litmus. (?) 

b. To what is the odor of the distillate chiefly due? 

c. Of what does the oily residue in the flask consist? How 
could you prove it? 

d. Remove the oily layer, wash it several times with water 
(?) and see if it dissolves in dilute sodium hydroxide solution. 
Add a drop of dilute acetic acid to the solution thus made. (?) 

e. Test a small portion of butter for unsaturated radicals 
with a solution of bromine in carbon tetrachloride. 

QUESTIONS 

1. What is a fat? a fatty oil? a mineral oil? 

2. What are soaps and how are they prepared? 

3. In your experiment what solution contained the soaps? 

4. What is the by-product when fats are saponified? How is it 

purified? 

5. What is rancid butter? Explain. 

*6. What is meant by the " saponification number '7 
7. What advantage has an alcoholic solution of potassium hy- 
droxide over an aqueous solution in saponifying fats? 

*8. How is the number of hydroxyl groups in a compound deter- 
mined? 

* Not required for study by students in the "short" course. 
108 



LABORATORY EXPERIMENTS 109 

9. What would happen if " nitroglycerine " was boiled with an 
alcoholic solution of potassium hydroxide? 

10. What is the difference in the behavior of the two esters, 

triolein and ethyl bromide, when boiled with alcoholic 
potassium hydroxide? , 

11. Can acids be used for hydrolyzing esters? Compare the 

rate of hydrolysis with alkali and with acid of corre- 
sponding " strengths." 

12. What is the irritating gas formed when a fat is heated alone? 

Explain. 

13. What are the products formed when lecithin is saponified 

with alkali? (Compare Expt. 27, p. no.) 

14. What is a wax? What difference from a fat is noted on 

saponification? 

15. How could you distinguish in the laboratory between a fatty 

oil and a mineral oil? between a fat and a wax? 



Experiment No. 27 

ISOLATION AND STUDY OF A NATURAL PRODUCT 
Lecithin from Egg-yolk 

Grind the yolk of one hard-boiled egg with 50 cc. of ether. 
Filter and wash the solid material twice with 10 cc. of ether. 
Discard the solid material. Evaporate the combined ether ex- 
tracts and washings on the steam-bath. Extract this residue 
twice with hot alcohol, using 10 cc. each time. Pour off the 
alcohol from the heavy oil through a small filter. Evaporate 
off the alcohol from the alcoholic filtrate, dissolve the residue in 
10 cc. of cold ether, and add 20 cc. of acetone. Stir until the 
particles of precipitated lecithin adhere together and form a 
ball. Describe its properties. 

Boil about one-fourth of the lecithin with about 10 cc. of 
a 2N solution of sodium hydroxide. Note <he odor of the gas 
evolved. What is it? Cool the solution. Is there any evidence 
of the formation of a soap? Filter, dissolve the precipitate in 
warm water and add dilute hydrochloric or Acetic acid to the solu- 
tion. What is precipitated? 

Test a part of the lecithin for nitrogen and for phosphorus 
(See Expt. 28, p. 112). Results? 

REFERENCES 

MacLean, "Lecithin and Allied Substances," (1918) (Longmans); 
Levene and West, " Lecithin, I. Hydrolecithin and its bearing on the 
constitution of cephalin," Journ. Biol. Chem., 33 (1918), 111-7. 
Levene and West, "Lecithin, II. Preparation of pure lecithin; 
composition and stability of lecithin cadmium chloride." Journ. 
Biol. Chem., 34 (1918), 175-86. 

110 



LABORATORY EXPERIMENTS 111 

QUESTIONS 

1. Write the structural formula of lecithin. 

2. Is lecithin a name for a single substance or is it a generic term? 

Explain. 

3. Why is the first extraction residue treated with hot alcohol? 

4. What are the physical properties of lecithin? 

5. What elements did you find present? 

6. What other methods could be used for decomposing the 

organic matter before testing for phosphate? 

7. What is choline? How is neurine related to it? Muscarine? 

Betaine? 



Experiment No. 28 

Detection of Nitrogen, Sulfur, the Halogens and Phosphorus 
in an Organic Compound 

Support a clean, dry, hard-glass (Pyrex) tube (9 mm. by 100 
mm.) in a clamp, using two pieces of cork about 5 mm. thick 
for protection, or pass the tube through a hole in an asbestos 
disc in such a way that the tube is supported by the flare at the 
top. Prepare a small piece of bright metallic sodium, 1 not more 
than 2 cmm. and drop it into the tube. Apply a very low 
blue flame (1.5 cm. long) now and then until the sodium melts 
and there is a layer of sodium vapor i cm. deep. Drop a small 
amount of the substance to be tested (diphenylthiourea, 
Ci3Hi2N2S, or lecithin) into the tube from the point of a knife 
blade, and continue the gentle heating while the decomposition 
is progressing, being careful not to drive the vapors of the sub- 
stance out of the tube by too strong heating. Finally bring the 
mass to red heat for a minute and then allow to cool to room 
temperature. 

In the meantime (for the sulfur test) prepare about 2 cc. of a 
dilute solution of ferrous sulfate, and also a very dilute solution 
of sodium nitroprusside, Na2(NO)Fe(CN) 5 , by adding a small 
crystal to 2 cc. of water. 

To the cool reaction-tube add two or three drops of alcohol 
to destroy any unused sodium. Use a stirring-rod to break up 
the charred mass. When the evolution of hydrogen has ceased 
cautiously add a drop or two of water. When it is certain 
that all the sodium is destroyed add more water. Filter through 
a small wet filter paper and rinse out the tube with three or 
four portions of water, making the total volume used about 
3 cc. The filtrate should be water-white. If it is colored, 
the decomposition was not complete and should be repeated. 

1 Return all sodium residues to the bottle. 
112 



LABORATORY EXPERIMENTS 113 

Make alkaline with sodium hydroxide solution, if not already 
so. Divide the filtrate into three portions. 

To one portion in a test-tube add two or three drops of 
the freshly prepared ferrous sulfate solution, and a very small 
amount of potassium fluoride. 1 Stopper the tube and rotate 
the contents only enough to mix the substance. Allow to stand 
five to ten minutes. Then acidify with dilute sulfuric acid 
(approx. normal). If nitrogen was present in the sample, 
a precipitate of Prussian blue will be formed. 

NOTE 

Hydrochloric acid is not used because the yellow color of the 
ferric chloride and the blue color of the fine precipitate will give a 
green color at the end, and sometimes no blue precipitate is formed. 

Dilute two or three drops of the second portion of the filtrate 
to 2 cc. and add a drop of the sodium nitroprusside solution. 
The presence of sulfur is shown by the appearance of a violet or 
purplish-violet color. This is a very delicate test for alkaline 
sulfides. An idea of the amount of sulfur present may be gained 
by acidifying the remainder of the second portion of the original 
filtrate with acetic acid and adding a solution of lead acetate. (?) 

To the third portion add just enough dilute hydrochloric acid 
to make the solution react acid, and then add two or three 
drops of ferric chloride solution. If a blood-red color is formed 
it indicates the presence of a thiocyanate. However, although 
nitrogen and sulfur may originally be present in the sample, 
this test may not be positive because the sodium thiocyanate 
first formed is sometimes decomposed by the metallic sodium 
into sodium sulfide and sodium cyanide. 

REFERENCE 

Viehover and Johns, "On the Determination of Small Quantities 
of Hydrogen Cyanide," Journ. Amer. Chem. Soc., 37 (1915), 601-7. 

This same general procedure can be used also for the detec- 
tion of other elements such as the halogens and phosphorus. 

1 It is not definitely known why the potassium fluoride is more efficient in aid- 
ing the precipitation of the Prussian blue than any other salt. Compare Viehover 
and Johns' reference above. 



114 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

For the halogens the fusion is carried out in the usual manner 
and the water-white nitrate is acidified with nitric acid, boiled 
(?) and treated with a few drops of silver nitrate solution. If it 
has already been shown that nitrogen and sulfur are absent it is 
not necessary to boil the solution (?). 

For phosphorus, use about i cc. of the nitrate from the 
sodium decomposition in the nitrogen test and boil this for one 
minute with 3 cc. of cone, nitric acid (?). Cool the solution and 
add twice its volume of ammonium molybdate reagent. Heat 
the tube to such a temperature that it can just be held in the hand, 
then set aside. If phosphorus was present in the original sample 
a yellow crystalline precipitate of ammonium phospho-molybdate 
will form. 

QUESTIONS 

1. At the end of the sodium decomposition, in what chemical 

combinations are the nitrogen and the sulfur found? 

2. How does the alcohol destroy the unattacked sodium? 

Why not use water at first? 

3. Write equations for the reactions involved in the test for 

nitrogen. 

4. Why is the mixture acidified with sulfuric acid rather than 

with hydrochloric acid? 

5. How else may sulfur be detected? 

6. Explain the ferric chloride test. 

7. Can the sodium method be used for detecting a halogen? 

Suppose a halogen and nitrogen are both present. (?) 

8. How is nitrogen detected, and also estimated, by the soda- 

Jime method? 

9. In what combination is the nitrogen when it can ordinarily 

be detected by the soda-lime method? 

10. What is the Kjeldahl method for the estimation of nitrogen? 
n. What is the Dumas or absolute method for the estimation 

of nitrogen? 



Experiment No. 29 

FORMATION OF AN ACID AMIDE FROM THE AMMONIUM SALT OF 

THE ACID 

Preparation of Acetamide from Ammonium Acetate 

The ammonium acetate used in this experiment should be 
as free from water as possible. Press out the material on a 
porous tile l if necessary. 

First Method 

Under a reflux condenser heat to gentle boiling a mixture 
of 15 grams of dry ammonium acetate and a little more than the 
same amount of glacial acetic acid for three to four hours. Cool, 
transfer the liquid to a 6o-cc. distilling-flask connected with a 
water condenser, and distill until the temperature reaches 160. 
Discard this portion. (Of what does it chiefly consist?) Replace 
the water condenser by a small distilling-flask, allowing the outlet 
tube of the first one to pass through the neck of the second one 
so that the distillate will be collected in the bulb of the second 
one. 2 Continue the distillation and collect the portion distilling 
above 160. Redistill this slowly as previously, but for a receiver 
attach to the outlet tube of the distilling-flask a small ordinary 
flask or large test-tube, which has been weighed, and with a cork 
containing a channel cut in the side. This time collect the 
portion distilling 2io-2i5. The product solidifies to a white 
crystalline mass. A third distillation may be necessary if it 
does not solidify on cooling. Pure acetamide boils at 222 cor. 
Yield, 10 grams. 

1 For use of porous tile, compare, foot-note, p. 56. 

2 It is not usually necessary to cool the receiving flask. If this is done, how- 
ever, care must be taken not to allow the condensate to solidify in the outlet tube 
of the main distilling-flask, since it may clog it and cause trouble. 

115 



116 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

The peculiar odor characteristic of mice excrement in the 
crude substance is due to an impurity which can generally be 
removed by re-crystallization. Acetamide is deliquescent and 
volatile at the ordinary temperature and pressure. It is easily 
soluble in chloroform and in alcohol, and difficultly soluble in 
ether. 

Recrystallization of Acetamide. Determine the weight of the 
crude product by weighing the receiver again. Add some 
chloroform, i cc. for each gram, to the flask or tube, attach a 
reflux condenser and heat to boiling by means of warm water. 
Chloroform boils at 61, and all the acetamide will be dissolved 
within a few minutes. Disconnect, and pour the clear hot 
solution into a small beaker and cover with a watch glass. 
Within a very short time the crystals will commence to form and 
the entire mass will quickly set to an apparent solid. Note 
the supercooling, and evolution of heat when crystallization 
begins. (Explain.) Cool further by placing the beaker in cold 
water or ice. Break up the crystalline mass with a stirring-rod 
and filter rapidly with suction, using a 5 cm. Buchner funnel 
(Fig. 8, p. 51), or the method for suction filtration of small 
quantities, p. 56. In the latter case use a 6-7 cm. funnel and 
moisten the little filter paper with chloroform before turning on 
the pump. Press the material down slightly with a spatula or 
glass stopper. On account of the very hygroscopic nature of 
acetamide the filtration must not be prolonged, otherwise the 
substance will liquefy. Yield, 80 per cent of crude product. 

i. t Heat some acetamide with dilute sodium hydroxide 
solution. What gas is evolved? Acidify with dilute sulfuric 
acid, and note the odor. (?) 

2. Heat a second portion of acetamide with dilute sulfuric 
acid. Odor of vapors? Neutralize the resulting mixture with 
dilute sodium hydroxide. (?) 

NOTE 

Save a one-gram sample of the acetamide for the methylamine 
experiment, p. 120. 



LABORATORY EXPERIMENTS 117 

Second Method (Sealed Tube MetJwd} 

Put 15 grams of ammonium acetate into an ordinary soft glass 
" bomb " tube, packing it in with a glass rod flattened at one 
end. The tube should not be more than half full when sealed. 
Two tubes may be used if desired. 

Sealing the Bomb Tubes. The open end of the tube is now 
sealed in the blow-pipe flame. This operation requires some 
care and a little skill. It is advisable to practice with an empty 
tube first. Grasp the tube about the middle with the left 
hand and while it is inclined at an angle of 45 heat about 5 cm. 
of the tube at the open end very gradually by revolving it 
for several minutes in a small smoky flame. Increase the size 
of the flame slowly until it is large enough to make the desired 
blue flame later by simply turning on the air only. Slowly turn 
on the air until a good blast flame, about 10 cm. in length, is 
obtained, and heat the end of the tube until it softens. At the 
same time heat the end of a glass rod, about 12 cm. long, held in 
the right hand, and seal it into the inside of the tube. Care 
must be taken to make a good seal not just to stick it on 
otherwise it will crack off when the tube is drawn out. Remem- 
ber that the hottest part of the flame is at the end of the inner 
blue cone. The glass is allowed to cool down slowly in the heat 
above the flame with the rod perfectly in line with the tube, and 
then smoked. Now warm the tube further down with the smoky 
flame, low at first. Gradually make the flame as hot as possible 
and about 7-10 cm. long, and heat the tube very hot around a 
point about 4 cm. below the open end to which the glass rod 
is attached, the glass rod now serving as a support while the 
tube is slowly rotated. The glass, evenly heated, begins to 
thicken where the flame plays upon it, and the inside diameter 
of the tube contracts. Rotate it carefully, do not draw it 
out, and keep the tube in line. This can be done easily if the 
glass rod is held as you would hold a pencil. When the inside 
diameter of the tube is reduced to about 5 mm. the tube is 
removed from the flame, and while held in a vertical position a 
capillary is formed by very slowly drawing out the thickened part 



118 LABORATORY MANUAL OF ORGANIC CHEMISTYY 

of the tube, and holding it there until it becomes rigid. It is 
then sealed off so as to leave a capillary about 4 cm. long. The 
capillary is necessary as will be seen later in opening the tube. 
Smoke the sealed end and allow the tube to stand with the warm 
end up until cold. Then remove the soot with filter paper or a 
cloth. The instructor must pass on all sealed tubes before they 
are heated in the furnace. 

Heating the Tube. Protect the eyes with goggles. The 
sealed tube is gently put into an iron jacket with the capillary 
at the open end. (See instructor.) Place it in the bomb 
furnace so that the open end of the jacket is towards the wall. 
Slide in the guard, see that the end of the furnace near the wall 
is raised and properly fastened, and then place a thermometer 
in the top of the furnace. Gradually, thirty to forty minutes, 
raise the temperature up to 2oo-2io, at which temperature 
the bomb is heated for three hours. Do not allow the tempera- 
ture to go higher because an explosion will result. The tem- 
perature should be noted about every thirty minutes. The 
heating can be interrupted at any time. 

Opening the Sealed Tubes. The tubes are always allowed 
to cool overnight. No one should enter the cannon room without 
wearing goggles to protect the eyes. In no case whatsoever should 
a sealed tube be taken out of the iron casing for examination or for 
any other purpose. When being opened the tube is held in such a 
position that neither the operator nor anyone else can be injured in 
case of bursting. The tube should be opened in the cannon room. 
It should never be taken out into the laboratory unopened. 

The contents of the tube are now liquid. The protecting 
case of iron, containing the tube, is removed from the furnace 
and held in a slightly inclined position, the end of the capillary 
being higher than the rear end. By means of a slight jerk the 
capillary of the glass tube is caused to project from the jacket. 
The extreme end of the capillary is now held in the flame of a 
Bunsen burner. If there is any internal pressure in the tube, 
the glass on becoming soft will be blown out and the gases will 
escape from the opening thus made. Should no gas be released 
even at red heat (which sometimes is the case in this experiment) 



LABORATORY EXPERIMENTS 119 

the end may be broken off by a sharp blow with a file. The glass 
tube is now taken out of the iron jacket. A deep file mark is 
made in the wide part of the tube about an inch below the 
" shoulder/' and this is touched lightly with the hot end of a 
glass rod previously heated to fusion in the blast flame. If 
the crack caused by this does not extend entirely around the 
tube, the extreme end of it is extended by applying the hot end 
of the glass rod again so that the conical end may be lifted off. 
Purify the product as in the first method above. 

QUESTIONS 

1. Why must the ammonium acetate be dry? 

2. Explain why the acetic acid is used in the first method. 

3. By means of structural formulas indicate the "steps" in the 

hydrolysis of a cyanide. 

4. How can acetamide be prepared from methyl cyanide? 

5. What is the action of phosphorus pentoxide on acetamide? 

6. What other methods are used for forming amides? 

7. How are the substituted amides prepared? E.g., acetanilide. 

8. What are the chemical properties of the amides as shown by 

their behavior toward (i) dry HC1 in ether, (2) bromine, 
(3) bromine and potassium hydroxide, *(4) mercuric 
oxide, (5) nitrous acid, *(6) PC1 5 , (7) aq. HC1? (8) 
aq. KOH? 

*g. What is an imide? How formed? Ex. succinimide. 
*io. What is the action of ale. KOH on an imide? What use is 
made of this reaction? 

ii. Look up the structure of urea and show how it is related 
to the amides. What is its chemical name? 

* These questions are not required for study in the "short" course. 



Experiment No. 30 

FORMATION AND STUDY OF A PRIMARY AMINE 

Methyl-amine from Acetamide 

- 

In a 60 cc. distilling-flask dissolve 2.5 grams of sodium 
hydroxide in 6 cc. of distilled water (ammonia free). Cool, 
and then (under the hood) cautiously add through a funnel 
i cc. of bromine (not bromine water). Shake and cool. Now 
add i gram of acetamide, stopper with a cork, slant the flask a 
little and allow the end of the outlet tube to dip just below the 
surface of 6 cc. of distilled water (ammonia free) contained in an 
open test-tube. Heat carefully with a small, moving flame l 
until the mixture becomes clear and vapors are vigorously 
evolved; then remove the flame, but resume the heating and con- 
tinue for several minutes after the main reaction has subsided. 
If the water in the receiver begins to run back remove the 
stopper temporarily. 

1. Note the odor. Is it exactly like that of ammonia? 

2. Test the reaction of the solution with neutral litmus. (?) 

3. Add a drop of the solution to i cc. of a very dilute solution 
of ferric chloride. (?) Repeat with dilute ammonium hydroxide 
instead of the amine solution. (?) Compare. 

4. Add a drop of the solution to i cc. of a very dilute solution 
of cupric sulfate. If the precipitate first formed does not 
dissolve add another drop of the solution. (?) Repeat, using 
dilute ammonium hydroxide. (?) To what is the color in each 
instance due? 

5. To the remainder of the solution in an evaporating dish 
add cone, hydrochloric acid drop by drop with stirring until 

1 Strongly alkaline solutions bump considerably. 
120 



LABORATORY EXPERIMENTS 121 

the solution reacts acid to litmus. What are the fumes? Evapo- 
rate to dryness on the water-bath. What is the white residue? 
Transfer the residue, 1 which is hygroscopic, to a test-tube and 
add a small amount of sodium hydroxide solution. Boil gently. 
Again note the odor of the vapors. Hold a stopper moistened 
with cone, hydrochloric acid near the mouth of the tube. (?) 
Test the inflammability of the gas. 

6. Add a drop of silver nitrate solution to a very dilute 
solution of ethyl ammonium chloride (ethylamine hydrochloride). 
Explain your result. 

QUESTIONS 

1. Explain the formation of methyl amine from acetamide. 

2. Why should you expect methyl amine to give an alkaline 

reaction in aqueous solution? 

3. Is methyl ammonium hydroxide a " stronger " base than 

ammonium hydroxide? Explain. 

4. Write the equations for the reaction with ferric chloride 

and with cupric sulfate. 

5. How does methyl amine react with hydrochloric acid? the 

product with sodium hydroxide? 

6. Compare the reaction of ethyl ammonium chloride and 

ethyl chloride with silver nitrate. How can you account 
for the difference? 

7. What is the carbyl amine (isonitrile) test for i amines? 

8. How can you distinguish between i, 2, and 3 amines? 

9. What compounds are formed by the treatment of amines with 

chlorplatinic acid? How can these salts be used for 
determining the molecular weights of the bases? 

10. Compare the action of bromine and sodium hydroxide on 

urea with the action of this same reagent on acetamide. 

11. What practical use is made of the reaction in No. 10? 

1 Save a few crystals of the hydrochloride for making methyl mustard oil, 
p. 123, 



Experiment No. 31 
Ethyl Isocyanate 

Grind together equal parts (about 0.5 gram) of dry potassium 
or sodium cyanate l and dry potassium ethyl sulfate. Place the 
mixture in a dry test-tube and heat carefully. A liquid soon 
begins to distill and partially condenses on the walls of the 
test-tube. Note its odor. (Care!) 

1. What is its structural formula? 

2. Why must the reacting substances be dry? Explain fully. 

3. What happens when the liquid obtained above is boiled 

with water? 

4. How do the isocyanates react with alcohol? Show how 

this reaction can be used in the identification of alcohols; 
also amines. 

5. Give the reasons for assigning the accepted structural formula 

for the isocyanates. 

6. Do esters of cyanic acid itself exist? Can you give any reason? 

1 Not cyanide. 



122 



Experiment No. 32 
Methyl Mustard Oil (Methyl Isothiocyanate) 

In a test-tube mix a few crystals of methyl amine hydro- 
chloride (Expt. 30, test 5, p. 120), one drop of carbon bisulfide, 
and one or two drops of a strong solution of sodium hydroxide. 
After a few seconds add a little water and slightly more than 
enough silver nitrate solution (N/io) to react with the potassium 
hydroxide. (?) Bring to a boil. The odor of the mustard oil 
will at once become pronounced. 

1. Outline all the " steps " in this reaction. 

2. Do all amines (i, 2, 3) give this reaction? Therefore, 

what use can be made of the reaction? 

3. How can you distinguish chemically between an isocyanate 

and a thiocyanate? 

4. Which compound of this series is found in true mustard oil? 

Does the name of its hydrocarbon radical have any sig- 
nificance in organic nomenclature? 



123 



Experiment No. 33 

HYDROLYTIC PREPARATION, SEPARATION AND PURIFICATION 
or AN AMINO ACID 

Preparation of Glycocoll (Glycine) from Hippuric Acid 

Heat to slow boiling i gram of hippuric acid and 15 cc. of 
cone, hydrochloric acid in a 250 cc. flask under reflux condenser 
for thirty minutes. During this time have a tube connected 
with the top of the condenser to lead the fumes into a flask con- 
taining dilute sodium hydroxide solution. The opening should 
be above the surface of the alkaline liquid and the flask should be 
loosely stoppered with cotton. Toward the end of the hydrol- 
ysis crystals (?) are deposited on the inside walls of the con- 
denser. 

After the thirty minutes' heating disconnect the apparatus, 
add 10 cc. of water to the main reaction mixture and cool with 
running water. Filter off the crystals with suction and save 
both the precipitate and the filtrate. Dry the white crystalline 
product and determine its melting-point. Test its solubility 
in ether. Dissolve out the deposit in the condenser with ether, 
evaporate the ether, and determine the melting-point of the 
residue. Compare with that obtained from the hydrochloric 
acid solution. 

Evaporate the filtrate to dryness on the water-bath. Add 
15 cc. of water and filter off any insoluble matter. Neutralize 
exactly with dilute sodium hydroxide solution, using litmus 
paper for the tests. Filter again, if necessary. Add about 
0.5 gram of basic copper carbonate and warm with stirring. A 
deep blue color is obtained which is characteristic of the solu- 
tions of the copper salt complexes of many of the monamino 
acids. Filter the solution while still hot and allow the filtrate 

124 



LABORATORY EXPERIMENTS 125 

to cool. Separate the blue needles of the copper salt complex 
which have been formed, and concentrate the filtrate to obtain 
a second portion. Dissolve the combined product in 20 cc. of 
warm water, saturate the warm solution with hydrogen sulfide 
gas (which has been washed with water), filter and carefully 
evaporate to dryness at a low temperature, 4O-5o, or allow to 
evaporate at room temperature. Complete the drying on the 
steam-bath. Extract the residue with a little water and filter 
off any copper sulfide with suction. Sometimes gravity filtra- 
tion and the use of a very small wet filter paper is better, espe- 
cially for a second filtration. The filtrate should be water 
white. 1 Concentrate the clear colorless solution to a small vol- 
ume and allow to crystallize in a small round-bottomed crystal- 
lizing dish. Beautiful crystals can be obtained in this way. 
Otherwise, when the volume of the solution is about i cc. or 
less, pour it into 3-4 cc. of alcohol with stirring. White needles 
will be precipitated. Set aside for complete precipitation, and 
filter before all the mother liquor has evaporated. (Why?) 
Dry and determine the melting-point of the pure white amino 
acid thus obtained. (?) What is the chemical name of this com- 
pound? Hand in the product and put the melting-point which 
you have found upon the label. 

NOTE 

The above experiment is a sort of "index" of your experimental 
skill. Only by very careful manipulation can the small amount of 
pure product be obtained. 

1 Sometimes considerable difficulty is experienced in removing all the copper 
sulfide and in getting the solution colorless. Apparently the copper sulfide forms 
a soluble complex with the ammo-acid, or is peptized by the excess of hydrogen 
sulfide and becomes colloidal. Similar difficulties are found in removing mer- 
curic sulfide from organic solutions. Warming with a good decolorizing carbon 
helps to remove both the copper sulfide and any color. If it is due to colloidal 
cupric sulfide then an excess of hydrogen sulfide should be avoided. An electro- 
lyte cannot be added to precipitate the colloidal material since it will contaminate 
the product, although a trace of an aluminium salt (which contains a trivalent 
ion) would be helpful if properly used. If the solution is heated too much the 
color is deepened and it is not easy to get rid of it. It is known, however, that 
you can evaporate a solution of pure glycocoll almost to dryness over a free flame 
without producing any color; in fact, no color is developed even if a little sulfuric 
acid is present. 



126 LABORATORY MANUAL OF ORGANIC CHEMISTRY 



QUESTIONS 

1. What is the structure of hippuric acid? Point out its 

chemical groupings. 

2. In the hydrolysis of hippuric acid what compounds are 

formed? Write their structures. 

3. Of what does the deposit in the condenser consist? 

4. Why is the reaction mixture diluted? 

5. Why is the filtrate evaporated to dry ness? 

6. What is left after the evaporation to dry ness? 

7. Write the reaction for the neutralization. (See also ques- 

tion No. n.) 

8. Why not use copper sulfate for preparing the copper salt? 

Could it be used at all? 

9. What advantage has a round-bottomed crystallizing dish 

over a flat-bottomed one. 

10. Discuss the structure of amino-acetic acid (glycocoll, glycine). 

Account for its high melting-point. 

11. How are amino acids estimated? 

12. Give three methods of forming glycocoll, including its 

preparation, for example, from gelatine. 

13. How can you prepare hippuric acid? 

14. What is glycyl-glycine? Its preparation by two different 

methods? 

15. Compare the structure of hippuric acid with that of a 

dipeptide. 

1 6. How are polypep tides prepared? 

17. How are the amino acids separated and identified in the 

mixture obtained by the hydrolysis of a protein? 

18. Give names and structures of the important amino acids. 



Experiment No. 34 
Hydrolysis of Cane Sugar and Preparation of Phenylglucosazone 

Dissolve 2 grams of cane sugar in 20 cc. of water. Test a 
few drops of this solution with Fehling's solution (mix 5 cc. of 
each part, boil, and then add the solution to be tested), and 
also test with ammoniacal silver nitrate. Result? Add 0.5 cc. 
of cone, hydrochloric acid to the main solution, and place the 
tube in water kept at 70 for five minutes. Cool under running 
water. Exactly neutralize 2-3 cc. with dilute ammonium 
hydroxide solution, and then test again with Fehling's solution 
and also with the ammoniacal silver nitrate. (?) If a light 
colored precipitate is obtained with the silver solution add more 
ammonium hydroxide until it dissolves. (?) Explain all re- 
sults. 

Neutralize with ammonium hydroxide 10 cc. of the hydro- 
lyzed sugar solution, make up to 20 cc. with water, place the solu- 
tion in a large test-tube (No. 3), and add 2 cc. of phenylhydra- 
zine l and 3 cc. of glacial acetic acid. Mix well. Stopper 
loosely with a cork to prevent evaporation, and set the tube into 
water which has been brought to boiling 2 and let stand for 
one-half hour. Masses of fine yellow crystals of the osazone 
soon settle out. Cool, filter off the osazone in a Buchner funnel, 
and wash with cold water. Recrystallize as follows: Place the 
yellow product in a 250 cc. Erlenmeyer flask and add a mixture 
of 1 20 cc. of alcohol and 60 cc. of water, attach an upright con- 
denser or cover with a small watch glass, set the flask on the steam- 
bath and heat until all or practically all the substance is dissolved. 

1 Phenylhydrazine is poisonous. Its vapors should not be breathed, and it 
should not be allowed to come into contact with the skin since it produces an 
intolerable itching. Dilute acetic acid will remove phenylhydrazine. 

2 Do not heat after placing the tube into the bath, otherwise a dark product 
jvi\\ be obtained. 

127 



128 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

In order to prevent crystallization in the filter, the solution 
should be filtered 1 at once through a fluted filter in a glass funnel 
set in a hot- water funnel, using a stirring rod to direct the flow of 
the hot solution into the filter. The hot- water funnel consists of a 
double-walled copper jacket for an ordinary funnel, with a side 
tube for heating the water within (Fig. 12). Steam may 
be passed into it instead of using water. If a burner is used, 
it must be removed when you are filtering inflammable liquids, 




HOT 



FUNNE 



FIG. 12. 



as in this case. The stem of the glass funnel should not project 
more than 2-3 cm. below the neck of the hot-water funnel. 

1 A fluted filter is made by first folding a large circular filter paper in the ordi- 
nary way. Then half open it, and bring one corner in to the center of the hemi- 
circle and crease the paper. Bring back this same corner to the edge of the fold 
just made, and crease again. Now fold this back to the middle line of the original 
hemicircle. Repeat with the other quadrant. This gives an alternating series of 
folds. When completely opened, it will be noticed that there are two places where 
the paper would lie flat against the walls of the funnel. Fold each one of these in a 
half fold to make them similar to the others. A fluted filter gives very rapid 
filtration. (Why?) 



LABORATORY EXPERIMENTS 129 

(Why?) The osazone almost immediately begins to crystallize 
out of the filtrate. Filter, when cold, with suction, and set aside 
the product to dry on a porous plate covered with a watch 
glass. Determine the melting-point. Pure phenylglucosazone 
is a bright yellow finely crystalline substance which melts at 
205-2o6 uncor.; or 208 cor., when the rate of heating is 
i in two to three seconds. 1 

The osazone should be prepared and recrystallized during 
one laboratory period. Yield, about 1.2 grams. 

NOTES 

1. Solubility of phenylglucosazone: 

o.oi part dissolves in 100 parts of boiling water. 
0.0042 part dissolves in 100 parts of water at 20. 
0.031 part dissolves in 100 parts of 5% acetic acid at 20. 

2. If the phenylhydrazine is not available, use instead of it 
and the acetic acid, 2 grams of phenylhydrazine hydrochloride and 
3 grams of crystalline sodium acetate. Explain. 

Phenylhydrazine hydrochloride when pure is a white crystalline 
substance, but when moist or impure it rapidly decomposes and 
darkens on keeping. Unless the pure white substance is used dark 
tarry spots will be found in the reaction mixture. These will be 
removed in the recrystallization unless there is a large amount. 

In connection, with the identification of sugars by means of the 
rate at which the osazone begins to precipitate, Mulliken describes 
the method of obtaining pure phenylhydrazine hydrochloride from 
phenylhydrazine, "Identification of Pure Organic Compounds," 
Vol. I, foot-note, p. 32. 

In order to prevent the decomposition Boeseken advises using 
the sulfite salt instead of the hydrochloride, Chem. Weekblad, 7, 
934; Chem. Abs., 5 (1911), 2078, 

3. Phenylglucosazone is also known as phenylfructosazone, and 
also as phenylmannosazone. (Why?) 

1 Garard and Sherman: Journ. Amer. Chem. Soc., 40 (1918), 957, and com- 
pare, p. 58 of melting-point experiment. 



130 LABORATORY MANUAL OF ORGANIC CHEMISTRY 



QUESTIONS 

1. Why would you expect cane sugar to be soluble in water? 

2. What are the two mono-saccharides in invert sugar? 

3. Write the structural formulas for cane sugar and the sub- 

stances in invert sugar. 

4. Show by means of its structure that cane sugar is an acetale. 

5. What does the behavior of cane sugar toward Fehling's 

solution and ammoniacal silver nitrate solution indicate 
in its structure? 

6. Why is the invert sugar solution neutralized with ammonium 

hydroxide solution before it is tested with Fehling's 
solution? 

7. What is the white precipitate formed when insufficient 

ammonium hydroxide is used in the silver mirror test? 

8. Explain why the same concentration of acetic acid as of 

hydrochloric acid in water would not hydrolyze cane sugar 
as rapidly. 

9. How can you show that cane sugar is an alcohol? 

10. Explain why it is that invert sugar can be oxidized by 

Fehling's solution although the larger portion of the 
mono-saccharides in it are known to be in the lactone 
form. 

11. Explain how the reaction between Fehling's solution and 

invert sugar can be used as a quantitative method for the 
estimation of cane sugar in the presence of known amounts 
of glucose. 

12. Explain why invert sugar yields only one osazone. 

13. For what purpose is acetic acid added in the formation of 

the glucosazone from the hydrolyzed cane sugar? 

14. Could strong hydrochloric acid be used in place of the 

glacial acetic acid in the formation of the osazone? 

15. Can invert sugar form hydrazones and if so what would be 

their chemical structure? 

1 6. Explain how the hydrazones and osazones are of value to 

the analyst in identifying sugars? 
*i7. Could any other hydrazines besides phenyl hydrazine be 

used for the purpose? Are they ever used, and why? 
*i8. Can you give any reason why the hydrazones of glucose and 

mannose should be different in physical properties since the 

two mono-saccharides differ only in a sterochemical way? 
*ig. What is formed when the osazone is heated with cone. 

hydrochloric acid? 



LABORATORY EXPERIMENTS 131 

*2o. How can d-glucose be transformed into d-fructose? into 

d-mannose? 
*2i. How can ^-fructose be transformed into d-glucose? 

22. What is oj-methyl glucoside? How prepared? 

23. Of what does the Benedict-Fehling solution consist? What 

advantage has it over the Fehling solution in the test 
for glucose in a physiological solution like urine? (Hawk, 
"Practical Physiological Chemistry/' 5th Ed. (igi6), 
27, 417-8; Plimmer, " Practical Organic and Bio-chemistry 
(1915), 191.) 

* These questions are not required for study in the "short" course. 



Experiment No. 35 
Pentoses (Furfural Test) 

A solution of a pentose is first made by the acid hydrolysis 
of a pentosan such as gum arable or an ordinary corn cob, and 
then the presence of the pentose is shown by the colored com- 
pound formed by the action of the decomposition product of the 
pentose with hydrochloric acid and aniline acetate. 

Make up 30 cc. of a solution of dilute hydrochloric acid ( sp.gr. 
i. 06) by mixing 9 cc. of cone, hydrochloric acid and 21 cc. of 
water. Pour 10 cc. of this dilute acid into a 100 cc. flask and add 
about 0.2 gram of gum arabic. Slowly bring to a boil over a. 
low flame and boil gently for five to ten minutes. Withdraw 
the flame, and while the vapors are coming out place in the mouth 
of the flask a roll of filter paper which has been soaked in a 
solution of aniline acetate, and from which the excess of the 
solution has been removed by pressing between filter papers, 
The test should be made while the paper is still moist. The 
aniline acetate solution is prepared by mixing 2 cc. each of 
aniline, glacial acetic acid and water. A bright crimson color 
on the aniline acetate paper indicates the presence of furfural 
from the action of the hydrochloric acid on the pentose. 

Repeat the above experiment, using 0.2 gram of ground 
corn cob. 

Some of the hexoses also give a pink color in this same test, 
but the color generally is not so pronounced. Repeat the 
experiment, using the same amount of cane sugar, and compare 
the color produced with that from the pentoses. 

REFERENCES 

For a discussion of this test see Sherman's "Organic Analysis," 
and for the probable composition of the colored compound formed on 

132 



LABORATORY EXPERIMENTS 133 

the test paper, see Richter's "Organische Chemie," n. Auflage, 
Vol. II, 713- 

QUESTIONS 

1. Write the stereo structures of the different possible pentoses, 

and name them. 

2. What substance is formed by the action of hydrochloric 

acid on a pentose? 

3. What are the pentoses obtained from gum arable, cherry 

gum, corn cobs, bran, etc.? 

4. To what class of cyclic compounds does furfural belong? 

5. What is a pentosan? 

6. How can pentoses be obtained from the pentosans? 

7. Name some substances which are or contain pentosans. 

8. Compare the pentosans with starch and cellulose. 

9. What is a galactan? 

10. What is the phloroglucinol test for furfural? 

11. How can the phloroglucinol test be used for the quantitative 

estimation of pentoses? (See Sherman's " Organic Anal- 
ysis.") 

12. Show how arabinose can be converted into glucose. 

13. Show how glucose can be converted into arabinose. 

14. What is a pentonic acid? How prepared? 



Experiment No. 36 

OXIDATION OF A SUGAR 

Mucic Acid from Lactose 

In a porcelain dish, 13-14 cm. in diameter, evaporate over a 
free flame a solution of 12 grams of lactose in 150 grams of nitric 
acid 1 of sp.gr. 1.15 to a volume of about 25 cc. with stirring 
towards the end. In order to remove the fumes support a large 
funnel over the dish and connect it with the suction pump. Do 
not heat so strongly that the material is charred on the sides 
of the evaporating dish. Brown fumes (?) are evolved, and 
the mass finally becomes thick and pasty owing to the separa- 
tion of mucic acid. When cold, dilute with water, filter with 
suction, and wash with small amounts of cold water. In order 
to determine the yield of crude product, dry it on a watch glass 
on the steam-bath or in an oven. 

To purify, dissolve the crude dry material in a cold solution 
of sodium hydroxide and re-precipitate with hydrochloric acid. 
Only the neutral salt is easily soluble in water, and its solubility 
is decreased by excess of alkali. (?) It is best therefore to 
calculate approximately the amount of N/2 sodium hydroxide 
solution necessary. Do not add dry solid sodium hydroxide to 
the water containing the mucic acid use a cold solution. Filter 
if necessary. If the solution is dark brown, decolorize by gently 
warming with animal charcoal, or filter through a funnel con- 
taining animal charcoal. Cool and add the equivalent of 5N 
hydrochloric acid 2 to set free the mucic acid. The hydro- 

1 The calculations can be made from the following data: The specific gravity 
of ordinary cone, nitric acid is 1.42. 

Nitric acid, 1.15, contains 24.84% HNO 3 by weight (15) 
Nitric acid, 1.42, contains 69.80% HNO 3 by weight (15) 

2 Cone, hydrochloric acid, sp. gr. 1.19, contains 37% HC1 by weight (15). 

134 



LABORATORY EXPERIMENTS 135 

chloric acid must not be added while the liquid is warm because 
part of the mucic acid may be converted into the easily soluble 
lactone. To complete the crystallization, allow the liquid to 
stand, then filter with suction, wash with cold water, and dry. 
Yield, 4 grams. Determine the melting-point. (?) Mucic 
acid is soluble one part in too of water at 14. 

Try the action of Fehling's solution on lactose. What does 
this indicate? 

NOTE 

The term "mucic" comes from the Latin word "mucus," mean- 
ing mucus or slime. Mucic acid has been known for many years, 
having early been prepared by the action of nitric acid on some plant 
mucilaginous material which contained galactans. The German 
name for mucic acid is "Schleimsaure." 

QUESTIONS 

1. Write the equations for all reactions involved in the pro- 

duction of mucic acid from lactose, indicating the various 
reactions by means of stereochemical structures. 

2. Explain why it is necessary to use nitric acid of about this 

particular strength, and give reasons. 

3. What is the action of cone, nitric acid on lactose? 

4. What significance is there in the fact that lactose reduces 

Fehling's solution? 

5. Which of the two mono-saccharides combined in the lactose 

molecule contains the " free " carbonyl group? How can 
this be shown? (The structural formula of lactose in 
Stoddard, " Introduction to Organic Chemistry," 2d Ed., 
p. 215, should be reversed.) Compare Holleman's 
" Organic Chemistry." 

6. What becomes of the saccharic acid and how does it differ 

from mucic acid structurally? Is it optically active? 

7. Can you give any reason why you would expect mucic acid 

not to have the same solubility as saccharic acid? 

8. Is this acid named d, /, racemic or meso mucic acid? Give 

reasons. 

9. What is the salt formed when sodium hydroxide reacts with 

mucic acid? Name? 

10. Why is it necessary to neutralize so carefully with sodium 
hydroxide? 



136 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

11. Write the structure of the lactone of mucic acid. 

12. To what class of organic compounds do the lactones belong? 

13. Are compounds like the lactones often formed by boiling 

water? 

14. Indicate the difference between an " acid lactone " and a 

" sugar lactone/' 

15. What is the chief organic impurity removed by the re- 

crystallization and washing? Is this obtained from other 
sugars likewise? 



Experiment No. 37 
Cellulose Acetate 

In a small Erlenmeyer flask place 20 cc. of glacial acetic 
acid, 6 cc. of acetic anhydride, 2 drops of cone, sulfuric acid, 
and 0.5 gram of absorbent cotton. Press the cotton into the 
solution with a glass stirring-rod, and after a few minutes stir 
it so that most of the air bubbles are removed. Stopper and let 
it stand overnight or longer. Pour the clear solution which is 
obtained in a thin stream, and with stirring, into 500 cc. of water. 
Filter with suction, using a large funnel. Press out between 
filter paper or on a porous tile until dry. Put about one-half 
the dry product in a small beaker or test-tube and add 20 cc. of 
chloroform. After standing some time the acetate should pass 
into solution. Pour the solution upon a watch glass and let it 
evaporate slowly. When the chloroform has evaporated, put 
some water into the watch glass and allow it to stand for a 
minute or two. Lift the edge of the film and remove it slowly 
from the glass. Dry the film and try its burning qualities. 
Test the solubility of the remainder of the acetate in glacial 
acetic acid, in alcohol, and in ether. 

QUESTIONS 

1. How is cellulose related to the simple sugars? 

2. Outline, in general, the reaction with acetic anhydride. 

3. What conclusion as to the groups in cellulose can you draw 

from this reaction? 

4. How does cone, sulfuric acid affect cellulose? 

5. How does a mixture of cone, nitric and sulfuric acids react 

with cellulose? 

6. What is a " tetra-nitrate," a " hexa-nitrate " of cellulose? 

7. What is smokeless powder? Celluloid? Collodion? 

8. How is artificial silk made? 

9. What is viscose? Explain its formation and use. 

10. What is mercerized cotton? 

11. Compare the action of the reagents mentioned in questions 

2, 4, and 5 on starch. 

137 



Experiment No. 38 
BENZENE: CHEMICAL PROPERTIES 

a. To 2 cc. of benzene, labeled " thiophene free," add 0.5 cc. 
of a dilute solution of bromine in carbontetrachloride. Does the 
color of the bromine disappear immediately? At all? 

b. (Hood.) Add several drops of bromine (not bromine 
water) to 5 cc. of benzene. Divide the solution into equal 
portions, and to one add some iron powder. Note the differ- 
ence in the velocity of the reaction in the two tubes. Breathe 
across the top of them. (?) 

c. Add several drops of benzene to i cc. of cone, sulfuric 
acid. Shake. Is there any evidence of chemical action apparent 
by the formation of heat or by darkening? Does the mixture 
become homogeneous? Pour it into 6 cc. of cold water, cool, 
stir, and then transfer to a No. i test-tube. Is a homogeneous 
solution obtained? Does benzene dissolve in hot cone, sulfuric 
acid? 

d. Repeat c., using fuming sulfuric acid. Pour the mixture 
drop by drop into cold water or better, upon ice. Result? 
(A solid substance, diphenylsulfone, may separate in the water 
solution. Explain.) 

e. Add several drops of benzene to i cc. of cone, nitric 
acid. Shake well for two minutes. Any heat formed? Then 
add slowly with cooling i cc. of cone, sulfuric acid. Shake. 
Any change? Pour into cold water and stir well. What is the 
heavy yellow oil that settles out in droplets? Note the odor. 

Is benzene reacted upon by fuming nitric acid? Try it. 

/. To i cc. of a very dilute solution of potassium perman- 
ganate in a small glass-stoppered bottle, add i cc. of benzene 
(" thiophene free ") Is there any change noticeable? 

138 



LABORATORY EXPERIMENTS 139 

Compare all the above reactions with benzine (in the Methane 
experiment, p. 31) and pinene (in the Ethylene experiment, p. 45). 

g. Determine the freezing-point of benzene by freezing some 
in a test-tube placed in ice and water. Stir the benzene with a 
thermometer until it solidifies. Note any super-cooling also. 

The true freezing-point of benzene is 5.483. See Richards 
and Shipley, " The Freezing-point of Benzene as a Fixed Point 
in Thermometry," Journ. Amer. Chem. Soc., 36 (1914), 1825. 

h. Small quantities of aromatic hydrocarbons are conveniently 
identified by converting them into solid nitro derivatives, usually 
the di-nitro-compound, and determining the melting-point. 

Mix i cc. of cone, sulfuric acid and i cc. of cone, nitric acid 
in a dry test-tube and add three drops of benzene. Heat to 
boiling and boil for thirty seconds. Cool and pour slowly into 
10 cc. of water in another test-tube. Shake. Filter off the 
bulky precipitate with suction, collecting it upon a small filter l 
and wash until the washings are no longer colored. Dissolve the 
substance with shaking in a boiling mixture of 4 cc. of alcohol 
and 4 cc. of water and set aside to crystallize. It crystallizes 
in long fine needles which are nearly white. Filter with suction 
and allow to dry upon a porous tile. Determine the melting- 
point of the w-dinitrobenzene formed, which should be 89.72 cor. 2 

Write the structure of the compound formed in this reaction. 
Can a similar compound of toluene be prepared with the same 
kind of acid mixture? 

HISTORICAL NOTE 

Faraday, in 1825, discovered a liquid hydrocarbon in compressed coal-gas 
which he called "bicarburet of hydrogen," since it had the empirical formula 
CaH (on the basis of the atomic weight of carbon being 6 which was used at that 
time). Mitscherlich, 1834, obtained the same hydrocarbon by the distillation of 
benzoic acid with slaked lime and termed it "benzin." He assumed that it was 
formed from the benzoic acid by the removal of CO 2 . Liebig denied this, adding 
the following editorial note to Mitscherlich's memoir in the "Annalen": "We 
have changed the name of the body obtained by Prof. Mitscherlich by the dry 
distillation of benzoic acid and lime and termed by him benzin, into benzol, because 

1 For filtration of small quantities with suction, see p. 56. 

2 For this method of preparation, see Mulliken, "Identification of Pure Organic 
Compounds," Vol. I, 200. 



140 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

the termination 'in' appears to denote an analogy between strychnine (German, 
strychnin) and quinine, etc., bodies to which it does not bear the slightest resem- 
blance, whilst the ending in 'oF corresponds better to its properties and mode of 
production. It would have been better perhaps if the name which the discoverer, 
Faraday, had given to this body had been retained, as its relation to benzoic acid 
and benzoyl compounds is not any closer than it is to that of the tar or coal from 
which it is obtained." A. W. Hofmann, in 1845, isolated the hydrocarbon from 
coal-tar. Later the name benzene came into use in accordance with the ending of 
unsaturated hydrocarbons. 

For many years, however, the ending "ol" has been used to denote an alcohol 
or a phenol. The term benzol is, therefore, considered a hybrid and a misnomer. 
Unfortunately the pronunciation of benzene is the same as that of benzine one 
of the petroleum fractions, but this can be remedied by using bcnzolene instead of 
benzine (see Note i, p. 33). 

REFERENCES 

Roscoe and Schorlemmer, "Treatise on Chemistry," Vol. Ill, Pt. Ill (1897), 
64; and "Resolution Concerning Organic Nomenclature," Journ. 2nd. and Eng. 
Chem., 10 (1918), 944. 



Experiment No. 39 

FITTIG'S SYNTHESIS OF AN AROMATIC HYDROCARBON 

Preparation of Ethylbenzene from Benzene and Ethyl 
Bromide 

Weigh out 12 grams of metallic sodium in lumps from which 
all the crust has been removed. Use a common knife or a pen- 
knife and dip the blade frequently into the kerosene with which 
the sodium is covered. Return all residues to the original 
bottle. Put the sodium into a dry 200 cc. round-bottomed 
flask and cover with 30 cc. of commercial xylene. Attach an 
addition tube and bulbed condenser with sealed joints l as a 
reflux condenser. Stopper the tube and heat the flask gently 
over a wire gauze until the sodium melts (m.p. 95.6, the xylene 
boils at i36-i4i). Do not heat the xylene to boiling. On 
account of the crust which forms about the sodium while exposed 
to the air, it often appears that the sodium does not melt because 
the melted globules are held by this covering. Disconnect while 
hot, stopper the flask with a good cork, place a folded towel 
at the bottom of the flask and another at the top to protect the 
hands, hold the flask in an upright position and shake vigorously 
in a vertical line for a moment until the sodium is broken into 
small globules " bird-shot " sodium. Let the flask rest upon a 
suberite ring 2 until cold. Do not shake too long, since the 
melted sodium may form one large lump. Now decant 3 the 
xylene into a dry beaker and quickly wash the sodium twice by 
decantation with 20 cc. portions of dry ether (" absolute ether " 

l li a condenser with rubber connections is used, the joints must be wired 
to make them perfectly tight. 

2 A suberite ring is a ring of pressed cork for supporting round-bottomed 
flasks. 

8 Do not decant the xylene or the ether into a wet beaker or into the sink. Par- 
ticles of sodium may thus come in contact with water. Destroy the sodium by 
adding alcohol. 

141 



142 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

or " ether over sodium ") Add 50 cc. of dry ether and re- 
assemble the apparatus, setting the flask in a beaker. In 
twenty to thirty minutes the ether, which is very hygroscopic 
and cannot ordinarily be kept dry, will be dry enough and 
practically no more bubbles will be given off. Now pour 
through the addition tube a mixture of 30 grams (20 cc.) of 
brombenzene and 30 grams (20 cc.) of ethyl bromide (an excess 
of the theoretical amount), and let stand overnight. If the liquid 
begins to boil vigorously cool by pouring cold water into the 
beaker. It should be watched for about an hour before leaving 
the laboratory. Do not allow the water to run through the 
condenser outside of laboratory hours! 

During the reaction the sodium is changed to a blue powder 
and an ethereal solution of ethylbenzene is formed. The next 
day remove the ether by distillation observing the ordinary 
precautions. The ether is practically all distilled when no more 
drops come over. Dry the outside of the flask, connect it in an 
inclined position, with the extreme end of the neck clamped 
loosely, to an air condenser with adapter attached leading into 
a receiver and loosely plug the annular space in the mouth of 
the receiver with cotton. Distill the crude ethylbenzene from 
the apparently dry residue by heating with a luminous flame 
which is kept in constant motion. Toward the end of the dis- 
tillation the heat may be increased. Since the ether is not 
entirely removed in the first distillation care must be taken in 
this operation and the eyes should be protected with goggles. 

Then subject the crude product to at least two fractionations. 
Use a small distilling flask and place into it a piece of pumice 
or tiling to aid ebullition. Carefully heat the flask directly with 
a very small flame. Collect separately the portions boiling below 
115, between ii5-i4o and above 140. Redistill each portion, 
collecting as the sample the part boiling between i33-i36. 
The boiling-point of pure ethylbenzene is 135.98 (760 mm.) 1 
cor. It is of great advantage in this fractionation to use a 
small round-bottomed flask surmounted by a Young four-pear 
still head, see Fig. 4, p. 25. Yield, 8 grams. 

1 T. W. Richards and F. Barry. Journ. Amer. Chem. Soc., 37 (1915), 998. 



LABORATORY EXPERIMENTS 143 

The residue in the original flask contains some sodium 
and must be handled with care. Remove the material and 
add it in small pieces to ethyl alcohol or acetone in a beaker, 
waiting until all the sodium in each piece has been destroyed 
before adding another. Dilute with water (Care!) before pour- 
ing the solution into the sink. Rinse out the flask with alcohol 
before adding any water. 

Sometimes crude amyl alcohol is used for destroying sodium 
residues. Its action is much slower, and, furthermore, globules of 
sodium are often found at the end of the main reaction coated 
with sodium amyl oxide, and their presence is sometimes not 
noticed until after water has been added! 

QUESTIONS 

1. Of what does the crust on the sodium consist? 

2. Name some other liquids that might be used to cover the 

sodium in the bottle. 

3. Why must the xylene be removed after making the " bird- 

shot " sodium? 

4. Compare the molecular and structural formulas of ethyl 

benzene and the xylenes. 

5. How could you distinguish chemically between the isomers, 

ethyl benzene and w-xylene? 

6. Why not add the brorrlbenzene and the ethyl bromide 

separately? 

7. Why must you wait until the ether is dry before proceeding? 

8. What two other organic compounds are formed in this 

reaction? What becomes of them? 

9. Is the reaction applicable to the aliphatic series? 

10. What is the object of the ether? Why is the " ether over 

sodium " used? What other substances could be used? 

11. Why must the condenser be perfectly tight? 

12. Why does not all the ether come over in the first distillation, 

since it boils at 35? 

13. Why is the flask dried after the distillation of the ether? 

14. Why is the flask inclined? 

15. What is the cause of the blue color? 

1 6. Why is the luminous flame kept in constant motion? 

17. Write the structure of the compounds formed when ethyl 

alcohol and sodium, and amyl alcohol and sodium react. 

1 8. Outline an apparatus for heating a reaction mixture above its 

boiling-point in a flask. (Gattermann, p. 280.) 



Experiment No. 40 

SYNTHESIS or AN AROMATIC HYDROCARBON BY MEANS OF 
FRIEDEL-CRAFTS' REACTION 

Preparation of Diphenylmethane from Benzene and Benzyl 

Chloride 

Attach an addition tube and dry reflux condenser to a dry 
300 cc. flask. Connect the top of the condenser with a tube 
leading into the draft pipe. Put 60 cc. of benzene, and 17 cc. 
of benzyl chloride l into the flask. Weigh out 5 grams of finely- 
pulverized anhydrous aluminium chloride 2 in a dry test-tube 
closed by a cork and add this in two portions (the second after 
the first reaction has subsided) to the mixture in the flask. Let 
stand until the evolution of hydrogen chloride has nearly stopped 
(thirty minutes). Then disconnect the apparatus and add 
40 grams of finely ground ice. (?) Shake, and after the ice 
has melted, separate the layers in a separatory funnel. The 
upper layer of benzene contains the diphenylmethane, and after 
the lower layer has been drawn off pour the upper layer from 
the top of the funnel. 

In order to remove the benzene most quickly and also leave 
the crude diphenylmethane in a small flask ready for the final 
fractionation, the solution is fractionated in portions under 
diminished pressure or in vacuo as follows: Connect a 125 cc. 
Claisen and an ordinary distilling-flask for distillation in vacuo 

1 The vapors of benzyl chloride are very irritating to the eyes and the mucous 
membranes of the nose and mouth. 

2 The sealed bottles in which the anhydrous aluminium chloride comes often 
contain considerable pressure. Great care is therefore necessary in opening them. 
Use the method described on p. 33, and completely wrap the bottle in a towel 
before striking the neck above the file mark a blow with the file. The aluminium 
chloride must be in good condition or the experiment will be a failure. 

144 



LABORATORY EXPERIMENTS 145 

(Expt. 15, p. 76), fill the upright one not more than one-third 
full of the solution, and, keeping the bath 4o-5o, distill until 
practically all the benzene and water have gone over. Equalize 
the pressure by slowly opening the stop-cock, take away the bath, 
cool, then add more of the solution. Continue these operations 
until all the benzene and water have been removed. The last 
time raise the temperature and stop the distillation when the 
diphenylmethane begins to distill. Attach a clean receiving- 
flask and then distill the residue. By keeping the temperature 
of the oil-bath constant where the diphenylmethane distills 
regularly no trouble with excessive foaming will be experienced. 
If the product is colored or does not completely solidify, redistill 
in vacua after adding two or three small pieces of sodium. 
(Why?) Destroy the sodium in the residue with alcohol. At 
22 mm. pressure diphenylmethane boils at 145 (at 760 mm., 
263). It is a clear heavy liquid which crystallizes to a solid 
white mass of needles on standing in the refrigerator or after 
adding a crystal of the substance (" seeding "). M. p., 25-26. 
It is partially decomposed when distilled under ordinary atmos- 
pheric pressure, and has an odor resembling that of orange- 
peel. Yield, 15 grams. 

QUESTIONS 

1. Why is the aluminium chloride weighed out in a closed 

test-tube? 

2. What causes the initial brown color when the AlCls is 

added? 

3. What is the purpose of the ice? 

4. What becomes of the aluminium chloride? 

5. Why is the product distilled in vacuo? 

6. Is there any advantage in removing the benzene in vacuo? 

7. Why is the benzene distilled off in portions in a small flask? 

8. What other possible compounds are formed in the reaction 

and remain in the " tar " in the fractionating flask? 
(Compare Gattermann, p. 323.) 

9. At the end of the distillation of the diphenylmethane the 

temperature often drops considerably although the bath 
is still at a high temperature. Explain. 



146 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

10. What other class of compounds can be made by the Friedel- 

Crafts reaction? 

11. Diphenylme thane on oxidation with chromic acid mixture 

yields benzophenonc. Is this reaction general with 
aromatic hydrocarbons? Compare triphenylme thane and 
diphenyl. 

12. What kind of halogen derivatives are used in the Friedel- 

Crafts reaction, aliphatic or aromatic, or both? 

13. Would there be any reaction between brombenzene and 

benzene in the presence of aluminium chloride? 

14. How could you prepare triphenyl-me thane? 

15. From its structure would you expect diphenylmethane to 

be soluble in benzene? 

16. Discuss the use of the aluminium-mercury couple in place 

of the aluminium chloride for preparing diphenylmethane, 
etc. (J. B. Cohen, " Organic Chemistry for Advanced 
Students/' Pt. I, 2d Ed. (1918), 198; and Norris, " Experi- 
mental Organic Chemistry " (1915), p. 132.) 



Experiment No. 41 

FORMATION OF A FREE RADICAL 

Triphenylmethyl 

Place 0.5 gram of triphenylchlormethane 1 and i gram of 
powdered zinc into a clean, dry, No. i test-tube. Seal a glass 
rod in the open end, soften the glass near this end in the blast 
flame and draw it out to a narrow tube about 2 mm. in diameter 
(compare sealing of a bomb tube, p. 117). When cold, pour in 
4 cc. of dry benzene 2 and after letting it drain well seal off 
the end of the tube. (Care!) Shake and allow it to remain 
in a horizontal position for two days. The heavy brown oil 
which separates on the bottom is a double compound of tri- 
phcnylmethyl and zinc chloride. At the end of the time specified 
open the tube and quickly divide its contents into two test-tubes. 
Have ready a solution of iodine in benzene and immediately test 
the unsaturated nature of the compound by slowly adding the 
iodine solution. (?) The other portion rapidly absorbs oxygen 
from the air and the insoluble triphenyl-methyl -peroxide is 
precipitated. 

REFERENCE 

Gomberg, "The Existence of Free Radicals," Journ. Amer. 
Chem. Soc., 36 (1914), 1144-70. 

1 Triphenylchlormethane must be kept in sealed bottles, since it will slowly be 
hydrolyzed by moisture in an ordinary cork-stoppered bottle. 

2 If the tube is so narrow that the benzene does not flow down readily, alter- 
nately warm the lower part of the tube with the hand, and cool, when the liquid 
will be drawn into the tube in small portions. Sometimes it will run down easily 
if the tube is inclined and the liquid poured in very slowly. 

147 



148 LABORATORY MANUAL OF ORGANIC CHEMISTRY 



QUESTIONS 

1. Is there any objection to the use of a larger test-tube in this 

experiment? 

2. Why must dry benzene be used? 

3. Explain the ready absorption of iodine by the solution. 

4. Write the formula for the compound formed when the solu- 

tion is exposed to the air. 

5. Compare some of the higher homologues of triphenylmethyl 

with triphenylmethyl itself, in regard to physical and 
chemical properties. (See Journ. Amer. Chem. Soc., 36 
(1914), 1165-6.) 

6. Discuss the question of the existence of free radicals. 



Experiment No. 42 

HALOGENATION OF AN AROMATIC HYDROCARBON 
Preparation of Brombenzene 

NOTE. This experiment must be allowed to stand overnight, but not longer 
than two or three days, since the monobrombenzene first formed is gradually 
converted into higher bromination products. 

Into a 200 cc. flask containing two small iron nails place 
20 cc. of benzene and 13 cc. (42 grams) of bromine (draft pipe). 
Immediately attach a reflux condenser with top connected with 
the draft pipe by means of a tube. In a short time an energetic 
action will begin, generally spontaneously, with the evolution 
of hydrogen bromide, 1 If necessary, warm slightly to start the 
reaction. Let stand overnight. Add water to the flask and 
wash twice by decantation, then in a separatory funnel wash with 
dilute sodium hydroxide solution 2 until the liquid is no longer 
acid, and again with water. Separate the liquids (sp. gr. of 
brombenzene is 1.489 at 21), dry with calcium chloride, 3 and 
distill, using an air condenser (p. 15). Collect the portion 
boiling between i4o-i7o and fractionate this two or three 
times narrowing the limits each time, collecting finally the por- 
tion between 154-6. The boiling-point of pure mono-brom- 
benzene is 155.5 cor. Yield, 18 grams. 

The crystals which are sometimes present in the original 
flask and the residue boiling above 170 in the distilling-flask 

1 This is a good method for preparing hydrobromic acid by absorption of the 
gas in water. 

2 If an emulsion is formed, it can be "broken" by making the mixture slightly 
acid with hydrochloric or sulfuric acid. 

3 If sufficient water has been extracted by the calcium chloride to form a solu- 
tion of the salt sometimes floating on the surface of the liquid, separate this aque- 
ous layer and add fresh calcium chloride. (Why is this necessary?) 

149 



150 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

consist mainly of ^-dibrombenzene. Dissolve this material in 
10-20 cc. of hot alcohol and filter the hot solution. If the 
filtrate is not water-white decolorize by adding animal charcoal, 
in small amounts to avoid excessive foaming of the hot liquid, 
cover with a watch glass, heat on the steam-bath for several 
minutes, and filter again while hot. Set the beaker aside for 
crystallization. Finally filter off the crystals of p-dibrombenzene 
with suction, dry and determine the melting-point. (?) 

a. Repeat experiment c under ethyl iodide (p. 38) using 
only a portion of a drop of brombenzene. Result? 

b. Repeat the same experiment using benzyl chloride. 

c. Repeat the above experiments, but use distilled water 
in place of the alcohol. Do not mistake an emulsion for a pre- 
cipitate. Compare results with those with the alcoholic solution. 

QUESTIONS 

1. What is the object of the iron nails? Why not use iron 

filings? Under what condition could the latter be used? 

2. What dibrom product is obtained in the experiment? Are 

any of the other two possible dibrom products formed at 
all? 

3. Why should the reaction mixture not be allowed to stand 

more than one or two days after the bromine has been 
added? 

4. What is the reddish-brown precipitate sometimes formed 

when the sodium hydroxide solution is added? 

5. How is benzyl bromide prepared? 

6. What are alpha- and beta-benzene hexabromides? (J. B. 

Cohen, " Organic Chemistry for Advanced Students/' 
Pt. II, 2d Ed. (1918), 260-3.) How prepared? 

7. What advantages has a separatory funnel over decantation, 

and decantation over a separatory funnel, for washing 
purposes? 

8. Compare the stability toward hydrolyzing reagents of the 

aryl halides with the alkyl halides. 

9. What compounds, if any, are formed by the action of alcoholic 

KOH on benzyl chloride; on i-phenyl-2-chlorpropane; 
picryl chloride; brombenzene? 

10. How can brombenzene be converted into benzene? Into 
diphenyl? 



LABORATORY EXPERIMENTS 151 

11. Give some of the modifications in the methods of using 

bromine for brominations. 

12. Give methods for preparing chlorbenzene from aniline; 

from chlorbenzoic acid; and for benzyl iodide from benzyl 
chloride. 

13. How are the iodo-derivatives prepared? 

14. Explain the action of the boneblack in decolorizing the solu- 

tion of dibrombenzene. 



Experiment No. 43 

SULFONATION OF AN AROMATIC HYDROCARBON 

Preparation of Benzene Sulfonic Acid, Sodium Salt 

To 5 cc. of fuming sulfuric acid in a test-tube, add in small 
portions 3 cc. of benzene, shaking vigorously and cooling after 
each addition. When the benzene has all dissolved and the liquid 
is clear, slowly pour it into 20 cc. of water in a flask, cooling it 
under running water. Filter off with suction any diphenyl- 
sulfone which separates. Partly neutralize by adding 4 grams 
of crystalline sodium carbonate, then add 5 grams of common 
salt. Warm and stir till it dissolves, filter while hot through a 
fluted 1 filter paper, and cool. Stir well when the solution is almost 
cold. The sodium benzene-sulfonate separates out in a mass of 
white lustrous plates. It may be necessary to set the beaker 
in ice in order to promote and complete the crystallization. 
Filter with suction. Press as dry as possible while it is in the 
funnel. Allow to dry on filter paper or press out on a porous 
plate. Recrystallize from hot alcohol. The pure sodium salt 
melts at about 450. Such a melting-point cannot be taken with 
the ordinary apparatus. Yield, 4 grams. 

NOTES 

i. A greenish color often develops during the sulfonation. This 
usually disappears in the recrystallization from alcohol. 

% 2. Sometimes the material does not crystallize out of the alco- 
holic solution very well. Possibly a soluble "alcoholate" similar to 
a "hydrate" is formed. Evaporation, thorough cooling, and stirring 
generally overcome the difficulty. 

1 See foot-note, p. 1 28. 
152 



LABORATORY EXPERIMENTS 153 



QUESTIONS 

1. What is fuming sulfuric acid? 

2. Could cone, sulfuric acid be used? How? 

3. Account for the formation of the diphenyl-sulfone. Would 

a lesser amount of sulfuric acid tend to increase or di- 
minish the amount formed? 

4. Why is the mixture partly neutralized with sodium car- 

bonate? 

5. Is it necessary to use the sodium carbonate for the forma- 

tion of the sodium benzene-sulfonate which crystallizes 
out, or would the sodium salt be formed and precipi- 
tated by adding sodium chloride alone? 

6. How could you filter a fuming sulfuric acid solution? 

7. What impurities does the sodium benzene-sulfonate con- 

tain before recrystallization? 

8. How may the product be freed from these impurities (No. 7)? 

9. Explain the formation of the sodium salt of benzene sulfonic 

acid by the theory of " salting out." 
*io. How are the corresponding calcium and barium salts 

prepared? 
*n. How is the free sulfonic acid obtained from these salts 

(No. 10)? 

12. How is the free sulfonic acid obtained from the lead salt? 
*i3. What mono-sulfo derivatives of naphthalene are prepared 
by direct sulfonation? 

14. Compare the structures of the sulfonic acids and of the 

nitro-compounds with relation to the acids from which 
they are derived. 

15. How can the sulfo-acids be converted into the parent hydro- 

carbon? 

16. How can the sulfo group be replaced by OH, by CN? 

* These questions are not required for study in the "short" course. 



Experiment No. 44 

NITRATION OF AN AROMATIC HYDROCARBON 
Preparation of Nitrobenzene 

In a flask carefully mix 18 cc. of cone, nitric acid and 18 cc. 
of cone, sulfuric acid, cooling under running water after each 
addition of one acid to the other. When the solution has come 
to the room temperature add it slowly from a dropping-funnel to 
13 cc. of benzene contained in an open 300 cc. flask, under the 
hood. (Do not use any cork or rubber connection.) Shake well 
and cool frequently under running water, keeping the temperature 
of the liquid below 50. When all the mixture has been added, 
half immerse the flask in water maintained at 50 by means of 
steam or a burner kept burning low and let it remain at this 
temperature for thirty minutes connected with a tube leading 
to the draft pipe. Since the mixture separates into layers on 
standing, it must be shaken occasionally during the heating. 
The nitration is complete when a drop which is added to water 
sinks to the bottom. The presence of any unchanged benzene 
will cause it to float. In performing this test stir well to make 
certain that any drops on the surface are not held up by surface 
tension alone. 

Pour the contents of the flask into about 500 cc. of water 
in another flask, shake thoroughly, cool it, and separate the lower 
turbid yellow layer of nitrobenzene by means of a separatory 
funnel. Return it to the funnel and wash the oil with sodium 
hydroxide solution until free from acid, and finally wash with 
water. Separate as completely as possible and return the oil to 
a dry separatory funnel. Add calcium chloride and shake. If 
an aqueous solution of the salt separates, remove it and add fresh 
calcium chloride. Repeat, and then transfer the liquid to a small 

1,54 



LABORATORY EXPERIMENTS 155 

Erlenmeyer flask, add several pieces of fresh calcium chloride, 
stopper, and allow to stand overnight to complete the drying. 
Be sure to clean the separatory funnel so that the stopper and 
stop-cock will not stick. It is well to keep the parts separated, 
but tied with a piece of twine. When dry the nitrobenzene will 
be clear. Filter through a funnel as usual containing a plug 
of glass wool into a dry distilling-flask with low outlet tube 
(style C). The stem of the funnel should reach below the open- 
ing of the delivery tube. Distill. Catch the first runnings, 
which consist chiefly of benzene and traces of water, direct from 
the outlet tube. When the clear yellowish nitrobenzene begins to 
distill attach a dry air condenser and distill, using a dry weighed 
specimen bottle as the receiver. Do not in any case allow the 
temperature to go more than 5 above the boiling-point: the 
residue sometimes decomposes explosively. 1 B.p. 210.9 cor - 
Yield, 17 grams. 

NOTE 

Nitrobenzene is a poison. Its vapor should not be breathed 
excessively and it should not be allowed to remain in contact with 
the skin. 

QUESTIONS 

1. Can nitrobenzene be prepared by adding benzene to the acid 

mixture, instead of the acid mixture to the benzene? 
Why is the method used in the laboratory preferred? 

2. What compound is formed if the temperature is allowed 

to rise much above 50? 

3. What is the object of the sulfuric acid? 

4. What compounds are formed by the " nitronation " 2 of 

toluene? Under what conditions does toluene yield ben- 
zoic acid when treated with nitric acid? 

1 This is most likely to happen when the product contains polynitro derivatives 
and also nitro derivatives of homologucs of benzene if a good quality of benzene 
was not used. 

2 The word "nitration" at present stands for the formation of both a true 
nitro derivative like nitrobenzene and of a nitrate like the cellulose nitrates. The 
term "nitronation" is suggested for the formation of a nitro derivative just as 
"sulfonation" stands for the formation of a sulfo derivative in a similar manner. 



156 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

5. Name some important classes of nitro-compounds and 

indicate their uses. 

6. Why must nitrobenzene not be heated above its boiling- 

point? 

7. How are most nitro-compounds purified? 

8. Are different products obtained when nitrobenzene is chlo- 

rinated and when chlorbenzene is nitrated? 

9. How are the conditions of nitration varied? Compare the 

preparation of nitrobenzene and of nitrophenol. 

10. What is the general chemical influence of the nitro-group? 

11. How are the aliphatic nitro-compounds prepared? Two 

methods. 

12. How is phenyl-nitro-me thane prepared? Why is this 

soluble in alkali? 

13. Compare the structure of nitro-compounds and the isomeric 

nitrites. 

14. What are the products of the reduction of nitro-compounds 

and of nitrites? 

15. What is a pseudo-acid? 

1 6. How are the alpha- and beta-mono-nitronaphthalenes pre- 

pared? 

17. How can the three different classes of aliphatic mono-nitro 

compounds be distinguished? 



Experiment No. 45 

REDUCTION OF A NITRO-COMPOUND TO AN AMINE 
Preparation of Aniline from Nitrobenzene 

To 15 grams of nitrobenzene and 35 grams of granulated tin, 
contained in a 500 cc. flask with a vertical air condenser attached, 
add in small portions 100 cc. of cone, hydrochloric acid. Shake 
the flask frequently. The mixture will become so warm that 
the reaction must be controlled by occasionally cooling the flask, 
but not enough to prevent the liquid from boiling quietly. After 
the first 50 cc. of acid have been added the second may be added 
in larger amounts of about 15 cc. with the same precautions. 
In order to effect the complete reduction of the nitrobenzene the 
mixture is finally heated for one-half hour on the steam-bath. 
The reaction mixture must be watched when first heated on the 
steam-bath, since if it were kept so cold in the beginning that the 
reaction was cut down too much, it will now suddenly become 
so violent that the unreduced nitrobenzene and the hydrochloric 
acid will be driven out of the tube of the condenser. During the 
reaction (and especially when cooled) the double salt of aniline 
hydrochloride and stannic 1 chloride (C G H 5 NH 2 HC1)2, SnCl 4 , 
separates out as a white crystalline solid. At the end of the 
operation when the odor of nitrobenzene has entirely disappeared, 
and a drop of the reaction mixture gives a clear solution in water 
(Why?) , add enough water to dissolve the salt, cool thoroughly, 
then pour off this solution from any unused tin into a separatory 
funnel. If any of the salt separates on cooling add more water to 
dissolve it. Extract the liquid twice with 60 cc. portions of 
ether, following the directions on p. 74. Remember when 

1 Stannous chloride forms a similar double salt, and a mixture is obtained here. 

157 



158 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

working with ether to keep away from free flames! Ether boils 
at 35, has a very high vapor pressure, and is very inflammable. 
Finally draw off the aqueous layer into a flask. The ethereal 
extracts should be discarded. 

(If the entire experiment cannot be completed at one time 
it should be interrupted at this point in order that the neutrali- 
zation with sodium hydroxide may be directly followed by the 
steam distillation, and the heat of neutralization thereby 
utilized.) 

The free amine (aniline) is obtained from the double salt in 
the extracted acid solution by adding gradually a solution of 
about 50 grams of sodium hydroxide in 90 cc. of water. Stannic 
and stannous hydroxides form at first and partially dissolve. 
The precipitate may be entirely dissolved by adding more sodium 
hydroxide, but this is not necessary. The mixture should have a 
strongly alkaline reaction. (Why?) If boiling occurs during 
the addition of the alkali, cool the solution under running water 
before adding more. (Why?) Most of the aniline rises to the 
top as an oil. 

The aniline could now be extracted with ether, but this is 
not advisable, since the alkaline solution forms a difficultly 
separable emulsion with the ether. 

Distillation with Steam. 1 The free aniline is separated by 
steam distillation, using the apparatus shown in Fig. 13. 

Steam is passed into the flask through a tube which is bent 
in such a way that it reaches almost to the bottom (Why?) 
when the flask is inclined. (Why is the flask inclined?) The 
outlet tube should be cut off just beneath the stopper (?) and 
the bend should be just above the stopper. (Why?) The outlet 
tube also should be of a larger diameter than the inlet tube. (?) 
The flask should not be more than half full when the distillation 
is begun. Use a long water condenser. Make the rubber con- 
nections as short as possible and attach the rubber tube to the 

References for the principles involved in distillation with steam: Morgan, 
"The Elements of Physical Chemistry," sth Ed. (1918), 177-8; Smith, "Introduc- 
tion to Inorganic Chemistry," 3d Ed. (1917), 563; Walker, "Introduction to 
Physical Chemistry," 7th Ed. (1913), 87. 



LABORATORY EXPERIMENTS 159 

inlet tube of the flask in such a way that it can easily and quickly 
be removed if occasion demands. Set the flask into a Babo- 
funnel l or upon a wire gauze, and heat gently during the opera- 
tion. (?) It is well to wrap a towel around the upper part of 
the flask (?). If the steam is passed into the solution when cold 
a " cracking " sound is often heard. This disappears as soon as 
the liquid becomes hot. 

The steam on the desk can be used as the supply. Since 
there is always considerable condensation water, a 500 cc. flask 

-Steam from 
the /aborafory 
Supply 




Diagram 
for Steam 



FIG. 13. 



should be placed as a trap between the steam nozzle and the 
apparatus. Use a three-holed stopper in this flask. The inlet 
and outlet tubes should be cut off just below the stopper. Into 
the third hole pass a glass tube leading to the bottom of the 
flask, bent downwards above the stopper and connected with a 
piece of rubber tubing to act as a siphon. Use a screw clamp 
to shut off the siphon. When the flask is nearly filled with 
water open the clamp and the water will go out and it is not neces- 
sary to stop the distillation during this time. If the screw clamp 

1 A Babo-funnel is an iron funnel partially lined with strips of asbestos, and is 
often used in place of an iron gauze. 



160 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

is partly opened and properly adjusted the water will pass out 
regularly without requiring further attention. 

Or steam can be generated in an ordinary tin oil-can, pro- 
vided with a safety tube 50 cm. long; the spout is used for the 
outlet. Or a flask may be used with a safety tube and outlet 
tube. The safety tube should extend almost to the bottom, 
and if a wide one is used, such as a condenser tube, it will also 
serve for pouring in the water, especially when the " boiler " 
is hot (although in such a case the " boiler " must not be con- 
nected with any apparatus when the water is being added 
unless boiling water is used). 

The distillation is considered complete when no more oily 
drops come over in the distillate (i to i^ hours). Remove the rub- 
ber connection from the main flask before turning off the steam 
or extinguishing the flame. Collect about 300 cc. of the cloudy 
distillate. Some of the aniline separates as an oil at the bottom 
of the receiver. Toward the end of the distillation, just after 
the oily drops have ceased to come over, collect separately 
2 cc. of the clear distillate and make the following two tests for 
dissolved aniline. 

To one portion add some bromine water. What is the 
white precipitate? 

To another portion add a small amount of a filtered water 
solution of good bleaching powder. (?) 

Ether Extraction. Saturate the steam distillate contained 
in a liter separatory funnel with powdered sodium chloride, 
25 grams for every 100 cc. of liquid. Then extract the aniline 
with ether, using three successive portions of ether, 50 cc. at first, 
then 30 cc. and 30 cc. Test a portion of the aqueous solution 
after the ether extractions to see if any aniline remains, in 
same manner that you tested the steam distillate above. Dry 
the combined ethereal solutions in an Erlenmeyer flask by 
adding two or three small sticks of solid sodium hydroxide. 
Stopper the flask with a cork and let stand overnight. If an 
aqueous solution of sodium hydroxide forms at the bottom, 
the layers should be separated, fresh sodium hydroxide added, 
and the mixture allowed to stand overnight "again. (?) (Cal- 



LABORATORY EXPERIMENTS 161 

cium chloride cannot be used for drying in this case because it 
forms a double compound with aniline.) 

Distillation. In order that the small amount of aniline 
remaining after the removal of the ether may be left in a small 
flask for the final distillation, the ether is distilled over in the 
following manner: Attach a dropping funnel to a 50 cc distilling 
flask. The stem of the funnel should reach into the bulb of the 
flask. Put in one or two pieces of porous tile. Do not add these 
after the ~olution has become warm since it may cause violent 
ebullition with loss of solution by overflow and imminent danger 
of fire. Connect the outlet tube with a straight water condenser 
and attach an adapter to the lower end of the condenser by means 
of a cork. In order to avoid circulation of ether vapors loosely 
plug the remaining space in the mouth of the receiver with 
cotton. Add the ethereal solution to the flask until it is one- 
third full. Heat the flask gently over the steam-bath and 
continue the addition at about the same rate at which the ether 
distills. 

When all the ether is distilled over, disconnect the apparatus 
and remove the ether distillate. Dry the outside of the dis- 
tilling-flask. (Why?) Insert a thermometer, connect with a 
dry air condenser, and distill the aniline, using a small free 
flame. Since there may be some ether remaining in the flask 
the initial heating should be carefully done. Collect the pure 
aniline in a dry weighed specimen bottle. It boils at 184.4 
cor.; its specific gravity is i.o2 1 4 ^oj and 100 cc. of water dis- 
solves 3.48 cc. of aniline at 22, and 100 cc. of aniline dissolves 
5.22 cc. of water at 22. When pure it is a colorless, oily, 
strongly refracting liquid, which becomes yellow and red on 
standing, especially when in the presence of air, and light, and 
possesses a peculiar odor common to many amines. Yield, 
10 grams. 

a. Shake a drop of pure aniline with a few cubic centimeters 
of pure distilled water (ammonia free), and test the clear solution 
with a piece of neutral litmus paper. What is the reaction? 

b. Add some of this solution to a solution of ferric chloride, 
and of zinc chloride. In view of the reaction shown in a, how do 



162 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

you account for the observation which you have made with 
these salt solutions? 

c. Dissolve two or three drops of aniline in the least possible 
amount of dilute hydrochloric acid. Why does aniline dissolve 
easily in acids while it is soluble with difficulty in water? Neu- 
tralize with sodium hydroxide solution. (?) 

d. To four or five drops of cone, sulfuric acid in a small 
porcelain evaporating dish add a drop of aniline on a stirring- 
rod. What is the white solid formed? Now add two or three 
drops of a water solution of sodium dichromate and stir. (?) 
Compare Holleman, " Organic Chemistry/' 4th Ed. (1914), 

457, 463- 

e. Add two or three drops of nitrobenzene to 0.5 cc. of 
aniline. Note the deep red color that is formed. (Compare 
Biron and Morguleva, " Color of Mixtures of Anilines with 
Aromatic Nitro Compounds." Journ. Russ. Phys. Chem. Soc., 
46 (1914), 1598; Chem. Abstracts, 9 (1915), 2069. 

QUESTIONS 

1. Write the equation for the reduction of nitrobenzene. 

2. Explain why only a little acid is necessary in the production 

of aniline commercially from nitrobenzene by means of iron 
as the reducing agent. 

3. Why is not all the hydrochloric acid added at one time when 

the nitrobenzene is reduced by tin and hydrochloric acid? 

4. Calculate the amount of hydrochloric acid necessary for this 

experiment. 

5. What is the nature of the salt formed from stannic chloride 

and aniline hydrochloride? How would this salt behave 
in a water solution? 

6. Is there any difference between a double salt and a complex 

salt? 

7. Why is it necessary to cool before extracting the nitro- 

benzene with ether? What is the principle underlying 
ether extraction? 

8. What does the ether extract contain and why is it desirable 

to perform this extraction? 

9. Could any other method be used in place of the ether extrac- 

tion? 



LABORATORY EXPERIMENTS 163 

10. How does sodium hydroxide react with the double salt? 

Write all equations for this chemical change. 

11. Show how aniline hydrochloride can be converted into 

aniline, writing the equation from the ionic standpoint. 

12. Why is it necessary to be careful in adding, the sodium 

hydroxide solution to the solution of the double salt? 
Explain why the liquid becomes hot. 

13. What is the gray precipitate that forms when a large excess 

of sodium hydroxide has been used? Account for it. 
(References, Mellor, " Modern Inorganic Chemistry/' 
790-1, and Ditte, Ann. Ckem. Phys. [5], 27 (1882), 145.) 

14. Discuss fully the principles involved in steam distillation. 

15. How can you tell by chemical means when all the aniline 

has been distilled over with steam? 

1 6. Why not continue the steam distillation until the distillate 

gives no test for aniline? 

17. Does aniline react alkaline toward litmus? Is it a true 

base? 

18. In a short time after the steam distillation has begun a 

considerable amount of aniline collects in the receiver, 
and by the time the distillation is completed practically 
all this aniline has disappeared. Explain. 

19. During the steam distillation some of the aniline collects 

at the bottom of the receiver, some floats on the water. 
Explain. 

20. Explain why aniline hydrochloride is not volatile with 

steam while aniline is. 

21. Would you expect phenyl ammonium hydroxide to be vola- 

tile with steam? 

22. What is the object of adding sodium chloride to the steam 

distillate before the ether extraction? 

23. Explain why the ether solution is dried with solid sodium 

hydroxide instead of calcium chloride or anhydrous 
sodium sulfate. Could the latter be used? 

24. Why is no jacket necessary for the condenser; would it do 

any harm if a condenser jacket were used? 

25. Point out the relationship between the double salt of stannic 

chloride and aniline hydrochloride, and ammonium chlor- 
platinate. 



Experiment No. 46 

ACETYLATION OF AN AROMATIC AMINE 

Preparation of Acet-0-toluidide from 0-Toluidine 

To 5 cc. of acetic anhydride 1 in a 125 cc. Erlenmeyer flask, 
add 2 drops of cone, sulfuric acid. Then add slowly in small 
portions, with shaking and cooling under running water after each 
addition, 4 cc. of 0-toluidine. Allow the mixture to stand at 
room temperature for one-half hour or longer. The entire product 
then appears like a solid mass. If it does not solidify, scratch 
the inside wall of the vessel with a glass rod to promote crystal- 
lization. Now add 30 cc. of water and warm on the steam- 
bath. This loosens the product and with the aid (careful!) of a 
stirring-rod disintegrate and transfer it to a 250 cc. flask. Make 
the volume up to 160 cc., using some of this water to rinse out 
the flask. Neutralize with ammonium hydroxide solution. 
(Why not NaOH?) Heat the flask on the steam-bath until 
solution takes place. Generally a pink solution is obtained. 
Sometimes the substance melts and collects at the bottom of 
the flask. Shake to dissolve it. Decolorize by adding, in small 
amounts, two spoonfuls of animal charcoal. Continue the heat- 
ing for about twenty minutes, with occasional shaking, then 
filter while hot through a large fluted filter in a hot-water funnel 
(see p. 128), and set the solution aside to crystallize. If the 
crystals obtained are colored they should be re-dissolved as before 
in hot water and heated again with animal charcoal. Filter 
off the needle-like crystals with suction by means of a Buchner 
funnel and let them dry between filter papers, or in a desiccator, 
or press them out on a porous tile. Concentrate the filtrate on 

1 Acetic anhydride attacks the skin and the mucous membranes. Be careful 
in handling it. 

164 



LABORATORY EXPERIMENTS 165 

the steam-bath to about 30 cc. volume, decolorize, if necessary, 
filter as before, and allow to cool. M. p., 1 10. Yield, 5 grams. 1 

a. Heat some of the crystals of acet-0-toluidide with a 
strong solution of sodium hydroxide. What is formed? Boil a 
few crystals with dilute sulfuric acid (i : i). Notice the odor 
of the vapor. (?) 

b. To 2 cc. of acetyl chloride add i cc. of 0-toluidine carefully. 
Warm and treat the product with water. Separate the crystals 
and recrystallize the substance from a little boiling water. 
Compare the melting-point of these crystals with the melting- 
point of a sample of the acet-0-toluidide prepared above. 

c. Grind together small dry portions of the pure acet-0- 
toluidide obtained in the main experiment and of the substance 
prepared in b, and determine the melting-point of the mixture. 
If the substances were not of the same chemical composition 
would the melting-point of the mixture be the same even though 
each substance originally had the same melting-point? 

d. Warm i cc. of acetyl chloride with i cc. of mono-methylanil- 
ine; then heat i cc. of acetyl chloride with r cc. of dimethylanil- 
ine. Pour each product into water. Is there evidence of chemi- 
cal change in each case? Are the reactions illustrated in b and 
d typical of primary, secondary, and tertiary amines in general? 

REFERENCES 

W. M. Dehn, " Acetylations in Ether Solutions," Jour. Amer. 
Chem. Soc., 34 (1912) 1399; Dehn and Ball, " Benzoylations in 
Ether Solutions," ibid., 36 (1914) 2091. 

NOTE 

Solutions of organic compounds should seldom be evaporated 
over a free flame. If any evaporation is necessary in the above 
experiment use a steam-bath. At low temperatures there is the least 
decomposition, and for this reason it is often best to evaporate under 
diminished pressure. 

1 This amount is too much for the usual preparation bottle to contain. Hand 
in a sample, stating the total yield on the label, and use the major portion for the 
preparation of acetanthranilic acid (p. 189). 



166 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

QUESTIONS 

T. Compare the structures of acetic anhydride, acetyl chloride, 
and acetyl sulfuric acid. How is the anhydride prepared? 

2. Explain the use of the " two drops of cone, sulfuric acid." 

3. Why is it necessary to neutralize the solution? 

4. What product is neutralized with ammonium hydroxide? 

5. What objection would there be to the use of sodium hydrox- 

ide? Could it be used at all? 

6. Why is a hot-water funnel used? Why must the stem of the 

funnel not project much below the metal collar? 

7. By means of structural formulas show how acet-0-toluidide 

differs from 0-toluidine acetate. 

8. What would be obtained by heating dry ammonium acetate? 

dry 0-toluidine acetate? Compare No. 9. 

9. To what class of organic compounds does acet-0-toluidide 

belong? 

*io. What advantage has acetic anhydride over acetyl chloride 
for acetylation? 

11. How is aniline acetylated commercially? Use of product? 

12. Do 3-amines react at all with acetyl chloride? (Sefc 

special references above.) 

*i3. What is the structure of diacetanilide? How prepared? 
*i4. Of what use in the laboratory is the acetylation of amines? 

* These questions are not required for study in the "short" course. 



Experiment No. 47 

SULFONATION OF AN AROMATIC AMINE 

Preparation of Sulfanilic Acid from Aniline 

Pour 50 grams of cone, sulfuric acid into a 100 cc. round- 
bottomed flask, then attach an air condenser, and through it 
add cautiously with moderate shaking 15 grams of aniline. 
Do not shake so vigorously that the sulfuric acid comes in contact 
with the upper portion of the flask or the lower part of the air 
condenser. The first reaction product (?) deposited at these 
places is not easily got down into the main portion. Half 
immerse the flask in an oil -bath, which consists of a shallow 
iron dish partly filled with rapeseed oil, 1 and heat the mixture 
of aniline sulfate and sulfuric acid at a temperature of 175- 
i8o, 2 thermometer in the oil, for three hours. Pour the par- 
tially cooled product with stirring into about 250 cc. of cold 
water, when the sulfanilic acid will separate out in crystals. 
Allow to stand for about twenty-four hours, then filter off the 
product with suction in a Buchner funnel. Wash once with a 
little cold water. 

Suspend the crystals thus obtained in 100 cc. of water and 
dissolve them by adding a 2N solution of sodium hydroxide until 
neutral to litmus. If the solution is water-white filter from 
any impurities, otherwise heat to boiling, decolorize by heating 
for about half an hour on the wate.*-bath with the addition of 
animal charcoal (added in small quantities to prevent foaming) 
and filter. Precipitate the sulfanilic acid in the filtrate by 
adding the calculated amount of hydrochloric acid (based 

1 Do not allow any water to come in contact with the hot oil. It causes violent 
foaming. Compare note 6, p. 82. 

2 A higher temperature causes considerable decomposition. The heating may 
be interrupted at any time. 

167 



168 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

on the theoretical yield) to liberate the acid from its sodium 
salt. Allow to stand overnight, filter with suction, wash with a 
little water, and dry the crystals between filter paper. Large 
rhombic plate crystals may be obtained by dissolving the sulf- 
anilic acid in just the sufficient amount of hot water for com- 
plete solution and allowing to cool slowly. The crystals con- 
tain 2 molecules of water of hydration, which is slowly lost 
in the air and the crystals fall to a powder. They are soluble 
in hot water but not very soluble in cold water. Yield, 15 grams. 
It has no definite melting-point, but decomposes 28o-30o. 

QUESTIONS 

1. What is the white solid first formed? 

2. If necessary, how could you filter the hot acid solution? 

3. Name sulf anilic acid to show its chemical groups and their 

position. 

4. Trace the changes from the compound first formed through 

the amide-form and the rearrangement to sulfanilic acid. 
(See J. B. Cohen, " Organic Chemistry for Advanced 
Students," Pt. II, 2d Ed. (1918), 371.) 

5. Why must the mixture not be heated above 180? 

6. How could a test be made to show that all the aniline has 

been converted into the sulfanilic acid? 

7. Why must an excess of sodium hydroxide be avoided? 

8. If you have added an excess of sodium hydroxide in trying 

to make the solution neutral how could you treat the solu- 
tion in order to obtain all the sulfanilic acid? 

9. Although sulfanilic acid is soluble in hot water the material 

is bone-blacked in an alkaline solution. Why? 

10. Explain the action of bone black (animal charcoal). 

11. Why must the calculated amount of HC1 be used? Why not 

simply add HC1 to acid reaction? 

12. What is naphthionic acid? 

13. Compare the chemical properties of the amino sulfonic acids 

and the amino carboxylic acids. 

14. What use is made of sulfanilic and similar acids? 

15. How can the meta-compound corresponding to sulfanilic 

acid be prepared? 



Experiment No. 48 
Benzidine Rearrangement 

Dissolve 2 grams of powdered sodium hydroxide in 20 cc. 
of alcohol in a large (No. 3) test-tube. Add 2 cc. of nitrobenzene 
and warm gently. During the course of several minutes add, 
in small quantities, about 5 grams of zinc dust. At first the solu- 
tion becomes deep red in color. This is due to the formation 
of azo-benzene. Later this color is discharged on account of the 
formation of hydrazo-benzene. Sometimes instead of a color- 
less solution a light brown solution is obtained. Then pour 
the mixture into about 50 cc. of water containing more than 
enough sulfuric acid to neutralize the sodium hydroxide used. 
(Why?) A colorless or slightly yellow precipitate of benzidine 
sulfate separates. There should be no oil (?) floating upon the 
surface. 

QUESTIONS 

1. Write the structures of the compounds formed in this reaction. 

2. Are all sulfates of mono- and di-amines insoluble in water? 

3. How could you prepare pure benzidine from this salt? 

4. Tabulate some important reactions in which it is believed the 

" benzidine rearrangement " takes place. (Ex., />-amino- 
phenol from phenyl hydroxylamine, />-phenylenediamine 
from phenyl hydrazine, sulfanilic acid from the amide of 
aniline sulfate, salicylic acid from sodium phenolate and 
carbon dioxide, amino-azobenzene from azo-amino-benzene, 
etc. J. B. Cohen, " Organic Chemistry for Advanced 
Students," Pt. II, 2d Ed. (1918), 369-75-) 

5. For what is benzidine used commercially? Example. 

6. Of what hydrocarbon is hydrazobenzene a derivative? ben- 

zidine? 

169 



Experiment No. 49 

DYES 

FORMATION OF AN Azo DYE 
Preparation of Methyl Orange 

NOTE 
Use amounts as nearly correct as possible. 

Make ready a solution of i.o gram of sodium hydroxide in 
10 cc. of water. In a small beaker, No. o, dissolve i.o gram of 
sulfanilic acid in 5 cc. of water and 2.4 cc. (i mol.) of the sodium 
hydroxide solution. Set the beaker in ice and diazotize by adding 
first a solution of 0.42 gram (i mol.) of sodium nitrite (which 
should be powdered to make it dissolve readily) in 2 cc. of water, 
and then slowly, with stirring, a solution of 0.5 cc. (i mol.) of 
cone, hydrochloric acid in 2 cc. of water. A reddish solution is 
often obtained. 

In a separate small beaker or test-tube mix 0.74 gram (about 
20 drops l ) (i mol.) of dimethylaniline and 0.37 gram (about 13 
drops *) (i mol.) of glacial acetic acid. Add this solution drop 
by drop, with constant stirring, to the diazotized solution. 
The dye begins to separate at once and forms a thick, dark red 
mass. Treat this with the remaining 7.6 cc. (3 mol.) of the 
sodium hydroxide solution and stir well. Filter off the reddish- 
yellow product with suction, using a hardened filter paper 2 or 
two ordinary filter papers in the bottom of the funnel. Re- 
crystallize the crude methyl orange from 20 cc. of hot water. 

1 From the lip of a 10 cc. graduated cylinder. 

2 A hardened filter paper is one which has been treated with cone, sulfuric acid. 
It is tough and smooth and has no loose fibres. 

170 



LABORATORY EXPERIMENTS 171 

Leaflets with a golden luster are thus obtained. Allow to dry 
on filter papers. Yield, 1.2 grams. 

NOTES 

Methyl orange is the sodium salt of the sulfonic acid, and its 
aqueous solution has a yellow color. On the addition of an acid the 
free sulfonic acid (Helianthine) is obtained, which has a red color in 
aqueous solution. The use of the dye as an indicator in acidimetry 
and alkalimetry depends upon this change in color. (For further 
discussion of this color change see Cohen, " Organic Chemistry," 
Vol. II (1913), P. 380.) 

STUDIES OF TRIPHENYLMETHANE DYES 
Phenolphthalein 

Mix o.i gram of phthalic anhydride and o.i gram of phenol 
in a test-tube, and add 2 drops of cone, sulfuric acid. Heat 
gently over a small flame with constant agitation for about two 
minutes. The melt will become dark red and the heating 
should not be so strong that the material blackens on account 
of extensive decomposition. When cold treat with 5 cc. of 
water, and add very gradually with shaking a dilute solution 
of sodium hydroxide until a permanent pink color is obtained 
(no more). Dilute a portion of this solution and test the suit- 
ability of the dissolved phenolphthalein as an indicator by adding 
first a trace of acid and then a trace of alkali. (?) 

Fluorescein 

Mix o.i gram each of phthalic anhydride and resorcinol in 
a test-tube and add 3-4 drops of cone, sulfuric acid. Heat 
gently for two minutes. Allow to cool, add 5 cc. of water, 
and make alkaline with sodium hydroxide. Transfer a drop of 
this solution to a test-tube full of water. (?) View by both 
reflected and transmitted light. 

Crystal Violet 

Place o.i gram of Michler's ketone (/^'-tetramethyl-diamino- 
benzophenone), 5 drops of dimethylaniline, and 2 drops of 



172 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

phosphorus oxychloridc in a test-tube, and heat the tube in 
boiling water for one-half hour. Add 10 cc. of water and stir. 

1. Add a drop of liquid to about 20 cc. of water and note 
the color. 

2. Add several drops to 20 cc. of water and treat with a 
little ammonium hydroxide solution. Let stand until the color 
has disappeared and white flocks are found in the liquid (several 
minutes) . Explain. 

To a portion of this decolorized solution, add very dilute 
hydrochloric acid until the color returns. Explain. 

3. To a second dilute portion of the original solution add 
dilute hydrochloric acid. What makes the green color which 
changes to yellowish? (See E. Q. Adams and L. Rosenstein, 
" The Color and lonization of Crystal Violet/' Journ. Amer. 
Cftem. Soc., 36 (1914); i45 2 -73-) 

4. To a third dilute portion of the original solution add a 
small amount of zinc dust and warm for a few minutes. Why 
does the color disappear? 

5. Allow the remainder of the original solution to stand 
overnight when crystals of crystal violet, which have a greenish 
luster, will separate out on the walls of the test-tube. 

REFERENCES 

Holleman, " Organic Chemistry," 4th Ed. (1914), 528. 

For a general discussion of color and structure, see Curtiss, 
"Relation between Color and Constitution," Journ. Amer. Chem. 
Soc., 32 (1910), 795. 

QUESTIONS 

METHYL ORANGE 

1. What is diazotization? 

2. What is the diazo structure? the diazonium structure? 

3. Write the structure of benzene diazoic acid; of benzene 

diazonium hydroxide. Why are these formulas assigned 
to the two isomers? 

4. Using structural formulas and equilibria equations, trace the 

course of the reaction in the formation of an amino-azo 
dye with the simplest preparation in the series, />-amino- 



*. 



LABORATORY EXPERIMENTS 173 

azo-benzene from aniline as follows: (i) phenylammonium 
hydroxide formed when aniline is dissolved in water, 
(2) the salt formed with hydrochloric acid (this is partially 
hydrolyzed), (3) the salt (nitrite) formed when nitrous 
acid is present, (4) the amide formed from this, (5) the 
tautomeric change to the diazoic acid, (6) the formation 
of the phenylammonium salt between the diazoic acid 
and a second molecule of phenylammonium hydroxide 
(added after the diazotization is complete), (7) the com- 
pound formed through the amide formation (azo-amino 
stage), (8) and the final rearrangement to the ^-amino- 
azo-benzene. 

5. Follow out the same scheme with sulfanilic acid and dimethyl 

aniline, using the proper modifications due to the presence 
of the sulfo group. 

6. Why is acetic acid used in the second part of the experiment 

instead of hydrochloric? Could hydrochloric be used? 

7. Why is sodium hydroxide added at the end of the reaction? 

8. What is a chromophore, an auxochrome group? Point 

out any such groups in methyl orange. 

9. Write the structure of methyl orange to show the presence of 

a quinoid nucleus, and also the changes involved in its 
use as an indicator. (Cohen, " Organic Chemistry/' 
II (1913), 380.) 

10. What is the leuco base of an azo dye? How obtained? 

1 1 . How can it be proved that in the making of methyl orange the 

coupling has taken place at the para position to the 
dimethylamino group? 

12. How is the coupling carried out (in acid, neutral, or alkaline 

solution)? Why? (Mohlau and Bucherer, " Farben- 
chemisches Praktikum," 118.) 

13. What are the congo dyes? How used in dyeing? 

*i4. What is a syn-diazo compound, and an anti-diazo corn- 
compound? 

*iS. Which one enters into a reaction? (Holleman, 413, 417-9; 
Mohlau and Bucherer, 70.) 

*i6. Why should the diazotized solution not stand overnight 
before coupling? 

*i7. How are the salts of the anti-diazo acid obtained? (Mohlau 
and Bucherer, 71.) Salts of the diazonium hydroxide in 
solid form? Give structures. 

18. How can you prepare phenylhydrazine? 

19. What is benzidine? How prepared? For what used? 

20. What are poly-azo dyes? How prepared? 



174 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

*2i. What is Bismarck brown? How is w-phenylenediamine 
hydrochloride used in the test for nitrites? 

PHENOLPHTHALEIN AND FLUORESCEIN 

22. What are the structural formulas of phenolphthalein and 

fluorescein? 

23. What are some of the derivatives of fluorescein? 

24. What is the theory for the color change in the use of phenol- 

phthalein as an indicator? 

CRYSTAL VIOLET 

25. What is the structural formula (quinoid) for crystal violet? 

26. Trace the course of the reaction beginning with the addition 

product formed from Michler's ketone and dimethylanil- 
ine, through the tautomeric change to the true base, and 
then the formation of the dye by neutralization with 
hydrochloric acid. 

27. Point out any chromophore and auxochrome groups in crys- 

tal violet. 

28. What is the parent substance of the fuchsine series? 

29. What is a color base? Illustrate in the case of crystal 

violet. How formed? 

30. Explain the changes that take place in the presence of the 

alkali. 

31. What is the structure of the leuco-base of crystal violet? 

How formed? 
*32. What happens when crystal violet is treated with cone. 

hydrochloric acid? 
*33. How is Michler's ketone manufactured? 

34. Are all colored substances dyes? 

35. What is a mordant? How used? 

36. What is a lake? 

37. What is a vat dye? How used? Ex. Indigo. 

38. What is rosaniline, fuchsine, or magenta? Para-rosaniline? 

How used in Scruff's aldehyde reagent? 
*3Q. What is malachite green? How prepared? 
*40. What is aurin? rosolic acid? How prepared? 
41. What is indigo? Summarize the steps in its manufacture. 
*42. What is alizarin? 
*43. What is the structure of indanthrene? (Mohlau and 

Bucherer, 225-6.) 

* These questions are not required for study in the " short " course. 



Experiment No. 60 
FORMATION OF A TRIPHENYLMETHANE DYE 

Preparation of Crystal Violet from Michler's Ketone 
and Dimethyl Aniline 

Heat a mixture of 6 cc. of dimethyl aniline, 2.5 grams of 
Michler's ketone (^'-tetramethyl-diamino-benzophenone), and 
2 cc. of phosphorus oxychloride, in a porcelain evaporating dish 
for 2\ hours on the steam-bath. Then transfer the blue-colored 
mass to a flask with water, make alkaline with a solution of 
sodium hydroxide (calculated on the basis of the amounts of the 
hydrolytic products of the phosphorus oxychloride), and distill 
with steam (see p. 158) until no drops of the unattacked di- 
methylaniline pass over (about three hours). After the addition 
of the sodium hydroxide the blue color should disappear either 
on standing or soon after the distillation is begun, and a reddish 
precipitate formed. If it does not, add more sodium hydroxide. 
(Explain the color change.) After cooling, filter the reddish, 
solidified color -base remaining in the distillation flask from the 
alkaline solution, wash with water, and boil with a mixture of 
250 cc. of water and 2 cc. of cone, hydrochloric acid. Filter the 
blue solution while hot from the undissolved color-base; and 
boil the latter again with a fresh quantity of the dilute hydro- 
chloric acid. This operation should be repeated until the sub- 
stance is almost entirely dissolved. On cooling and standing, 
the crystal violet separates out in beautiful needle crystals of a 
greenish color. Filter and dry in the air on filter paper. A 
further quantity may be obtained by adding finely pulverized 
salt to the filtrate (" salting out ") Yield, about 4 grams. 

Make a dilute solution of the crystal violet and perform 
experiments 2-4 given under crystal violet on p. 172. 

175 



176 LABORATORY MANUAL OF ORGANIC CHEMISTRY 



QUESTIONS 

1. What is a " condensing " agent? 

2. Why must the mixture be alkaline before distilling with 

steam? 

3. Why must dilute hydrochloric acid be used for preparing the 

dye? What happens when stronger acid is used? 
Answer also questions 25-43, p. 174. 



Experiment No. 51 

FORMATION OF A PHENOL FROM A PRIMARY AROMATIC AMINE 
BY MEANS OF THE DIAZO REACTION 

Preparation of Phenol from Aniline 

Pour 10 cc. of cone, sulfuric acid rapidly, with stirring, 
into 50 cc. of water, and to the hot solution slowly add 10 cc. of 
aniline, with constant stirring to make complete solution. 1 
(What is the white solid first formed?) Transfer to a liter flask, 
then add 200 cc. of water. Diazotize by treating the cold solu- 
tion with the calculated amount of sodium nitrite (powdered to 
make it dissolve readily) contained in about 40 cc. of water. 
Heat on the steam-bath for thirty minutes at a temperature 
between 4o-5o, with the thermometer in the liquid. (What gas 
is evolved?) The phenol is then distilled over with steam. 
(See Aniline Experiment, p. 158.) 

Collect about 600 cc. of distillate (about 1.5-2 hours are re- 
quired). When near the end of the distillation test the clear 
distillate with bromine water and ferric chloride, according to the 
directions given below in c and d. (?) Compare with aniline, 
p. 1 60. Saturate this distillate, contained in a liter separatory 
funnel, with finely powdered sodium chloride, 25 grams for every 
100 cc. of liquid, and extract the solution three times with 
ether (p. 74), using 50 cc. of ether for the first extraction and 
30 cc. each for the other two. 

Filter the combined ethereal extracts through a fluted 
filter 2 to remove any brownish impurities from the salt, and 
then dry with anhydrous sodium sulfate. In order that the 
small amount of phenol remaining after the removal of the 

1 Any precipitate which separates on cooling will dissolve when the solution is 
diluted. 

2 See foot-note, p. 128. 

177 



178 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

ether may be left in a small flask for the final distillation, the 
ether is distilled over in the manner described in the Aniline 
Experiment, p. 161. Distill the residue, using a short wide tube 
or an adapter as an air condenser. B.p. 183, m.p. 42.5. The 
specimen should be white and should solidify, especially when the 
tube is placed in cold water. If it is colored re-distill carefully. 
Yield, 8 grams. 

Reactions of Phenol and Derivatives 

a. Test the reaction of an aqueous solution of phenol with 
neutral litmus paper. 

b. Add a little sodium hydroxide solution to i gram of 
phenol. Now acidify with hydrochloric acid. Do not use too 
much water. Any change? 

c. Dissolve a drop of phenol in water and add bromine 
water until it is no longer absorbed. Filter off the precipitate 
and wash it with a dilute solution of sulfur dioxide or of sodium 
hydrogen sulfite until there is a strong odor of sulfur dioxide. 
Wash with water. Dissolve in about 5 cc. of hot alcohol, filter, 
add 10 cc. of hot water, and set aside to crystallize. Dry it on a 
porous tile and determine its melting-point. For what is this 
reaction used? Compare with the action of bromine and of 
bromine water on benzene (p. 138), and on amylene (p. 45). 

NOTE 

The sulphur dioxide converts any BraCoEfoOBr into tribrom- 
phenol, Br 3 C G H 2 OH. 

d. To a dilute solution of phenol add a drop of 5- molar ferric 
chloride solution. (?) 

e. Add a drop of ferric chloride solution to dilute solutions 
of catechol, resorcinol, salicylic acid and gallic acid. (?) Com- 
pare the structures of these compounds. 

/. Try the action of ferric chloride on a solution containing 
a drop of acetacetic ester and on another containing a drop of 
ace ty lace tone. Use alcohol in each case to make the solution 
homogeneous. What is meant by the enol and the keto form? 



LABORATORY EXPERIMENTS 179 

To which one is this color reaction supposed to be due? Do 

all hydroxyl compounds give color reactions with ferric chloride? 

Also compare the action of ferric chloride on aromatic 

amines (aniline), and on alpha-hydroxy acids, like tartaric acid. 

QUESTIONS 

1. How does aniline differ from ammonia? Compare the action 

of nitrous acid in each case. 

2. Why is aniline first treated with sulfuric acid? 

3. What compound is formed when aniline and sulfuric acid 

react? 

4. Would there be any objection to using too little sodium 

nitrite? too much? 

5. What reason is there for heating the diazotized solution? 

6. Calculate the amount of sulphuric acid theoretically neces- 

sary for converting 10 grams of aniline into phenol, and 
compare with the amount used. 

7. Explain the principle of steam distillation. 

8. Why is steam distillation used in this experiment? 

9. How can you tell by chemical means when all the phenol 

has been distilled over with steam? 

10. Why not continue the steam distillation until the distillate 

gives no test for phenol? 

11. Why is the distillate saturated with salt before extraction? 

12. What advantage is there in extracting the solution three 

times with small amounts of ether, instead of once with 
a larger amount of ether? 

13. How can anhydrous sodium sulfate be used as a drying 

agent? 

14. Where does the moisture taken up by the sodium sulfate 

come from? 

15. Is this method for the formation of phenols practical? 

1 6. Can this method of replacing an amino group with hydroxyl 

be used in the case of aliphatic amines? 

17. What advantage is there in distilling the ether from a small 

flask? 

18. How can phenol be prepared from benzene sulphonic acid? 

19. Compare the behavior of ethyl alcohol and phenol when 

treated with bromine. 

20. Compare the action of the halogens and of nitric acid on 

phenol and on benzene. 

21. What is the action of acetyl chloride; and of zinc dust, on 

phenol? 



Experiment No. 52 

ALKYLATION OF AN HYDROXYL GROUP 

Preparation of Anisole (Methyl-phenyl Ether) from Phenol and 

Dimethylsulfate 

Perform this experiment with apparatus connected with the 
draft pipe. Dimethylsulfate has no odor, but it is very poison- 
ous to some people. Be careful not to breathe its vapors and 
since it is readily absorbed do not allow any to come in contact 
with the skin. If any be spilt upon the clothes these should be 
changed immediately. 

Dissolve 12 grams of phenol l in a solution of 10 grams of 
sodium hydroxide and 100 cc. of water. Pour this into a 250 cc. 
flask and add slowly and with continuous shaking 25 grams of 
dime thy Isulf ate. 2 Place a thermometer in the mixture. 
There is a slight rise in temperature, which should not be 
allowed to exceed 40 (cooling is usually not necessary). The 
clear liquid becomes turbid and in a few minutes a layer of oil 
will float on the surface. The reaction may be considered com- 
plete when the temperature no longer rises and the products 
cool. 

To destroy the excess of dimethylsulfate (dry the flask if 
it has been placed in water), attach an upright air condenser, 
and heat the mixture to the boiling-point with frequent shaking. 
(How does this destroy the dimethylsulfate?) Finally, cool 
the liquid, add a solution of 6 grams of sodium hydroxide in 60 

1 Melt it by placing the bottle in warm water. If phenol should come in con- 
tact with the skin use dilute alcohol immediately. 

2 Opening sealed bottles : Wrap the bottle in a towel, leaving the narrow 
sealed end protruding, and make a file mark around the tube near the end. Hold 
it over a beaker in a slanting position and knock off the end with a sharp blow of 
the file, or touch the mark with the hot fused end of a glass rod. 

180 



LABORATORY EXPERIMENTS 181 

cc. of water, and extract once with ether. The liquid must be 
alkaline when the extraction is made. It cannot be tested 
directly since the oil would prevent the litmus paper from ab- 
sorbing water and indicating. Test a drop drawn off from the 
liquid in the separatory funnel. Dry the ethereal solution with 
calcium chloride. Remove the ether by distillation, observing 
the ordinary precautions (see p. 70), and then distill the anisole. 
The boiling-point of anisole is 153.9 cor - The yield amounts 
to about 95 per cent of the theory. 

QUESTIONS 

1. Write all the reactions involved in the formation of anisole 

from phenol, upon the assumption that an " oxonium " 
compound is formed as an intermediate product. 

2. How is dimethylsulfate prepared? 

3. What advantages has it over methyl iodide as a me thy 1- 

ating agent? over diazomethane? 

4. Why is the sodium hydroxide used? 

5. Why must the temperature of the mixture be kept under 40? 

6. Would an excess of dimethylsulfate be likely to affect the 

yield of anisole? 

7. To what class of organic compounds does anisole belong? 

dimethylsulfate? 

8. Could dimethylsulfate be used for alkylating the hydroxyl 

group in water, ethyl alcohol, and acetic acid? Equations. 

9. Does it make any difference as to the order in which the 

dimethylsulfate, phenol, and sodium hydroxide are 
mixed? 

10. Why is the anisole mixture made slightly alkaline before 

extracting with ether? 

11. Could anhydrous sodium sulfate be used in place of calcium 

chloride for drying the ethereal solution of anisole? 

12. How can anisole be changed into phenol? 

13. What is the Zeisel method of estimating methoxy groups in 

alkaloids, etc.? 

14. Could dimethylsulfate be used for methylating amino- and 

imino-groups? Examples. 

15. How can pure mono-methyl aniline be prepared? 

16. What is the action, if any, of bromine, cone, nitric acid, 

cone, sulfuric acid, cone, sodium hydroxide, potassium 
permanganate, and alcoholic potassium hydroxide at a 
high temperature, on anisole? 



Experiment No. 53 
BENZALDEHYDE 

Perform the following reactions: 

1. Silver-mirror test. Make an ammoniacal solution of 
silver nitrate, as given under Acetaldehyde, p. 91, and add a drop 
of sodium hydroxide solution. If a precipitate forms dissolve it 
with a little more ammonium hydroxide. Add a single drop 
(or a lesser amount) of benzaldehyde, shake, and let stand. 
The mirror forms very slowly. 

2. Try the action of the fuchsine-sulfurous acid reagent 
(SchifTs aldehyde reagent) p. 92, on benzaldehyde. If the 
drop of benzaldehyde is run down the side of the test-tube it 
will float on the surface of the solution and will assume the 
color of the fuchsine without coloring the entire solution. 

3. Does benzaldehyde reduce Fchling's solution? Try it. 

4. Add several drops of benzaldehyde to 2 or 3 cc. of a 
saturated solution of sodium bisulfite, and shake vigorously. 
Of what do the white crystals consist? Filter with suction and 
then warm with a solution of sodium carbonate. (?) 

5. Add a drop of benzaldehyde to a solution of a drop of 
phenylhydrazine in 3 cc. of dilute acetic acid (i : i). What is the 
yellow precipitate? 

6. Rub a drop of benzaldehyde on a watch glass. What are 
the crystals that form after a short time? 

7. Make a very dilute solution of soluble starch and add to 
it a few drops of dilute potassium iodide solution. Spread a 
drop of benzaldehyde on a watch glass with the aid of a stirring- 
rod. Allow it to remain for a minute or two, and then add a 
few drops of the starch-potassium iodide solution. Set the 
watch glass over a filter paper, and stir with the rod. Explain 
the formation of the blue color (see Question 9 below). 

Which of the above reactions are also characteristic of 
ketones? 

182 



LABORATORY EXPERIMENTS 183 

8. In a test-tube thoroughly mix about o.i gram of cin- 
namic acid and about 5 cc. of a cold strong solution of potassium 
permanganate. Note the odor. Explain. 

What type of unsaturated aromatic compounds, with relation 
to the position of the double bond, undergo this reaction? 

Outline the commercial preparation of vanillin from eugenol 
and of piperonal from safrol. (Holleman, " Organic Chemistry/' 
4th Ed. (1914), 482-5; Stoddard, "Introduction to Organic 
Chemistry," 2d Ed. (1918), 347, 342.) 

QUESTIONS 

1. Does benzaldehyde react with Fehling's solution? 

2. Write equations and complete structures involved in the 

reactions between benzaldehyde and sodium hydrogen 
sulfite, and between the product and sodium carbonate. 

3. Could a dilute solution of acid sodium sulfite be used instead 

of the concentrated? 

4. Could any other reagent be used in place of the sodium car- 

bonate? 

5. Write equations and structures for the reaction with phenyl- 

hydrazine. 

6. Could 50 per cent hydrochloric acid be used in place of 

the 50 per cent acetic acid? 

7. Could phenylhydrazine hydrochloride be used? What 

modification is generally necessary? 

8. Could hydrazine itself be used? *Semicarbazide? (Per- 

kin and Kipping, " Organic Chemistry/' New Ed., 
(1911), 456. 

9. What happens when benzaldehyde is exposed to the air? 

(For discussion of autoxidation, see Holleman, " Organic 
Chemistry/' 4th Ed. (1914), 428; and Bayliss, " Principles 
of General Physiology" (1915), 580.) 

10. Explain what takes place in the experiment with starch and 

potassium iodide. 

11. Write equations for the reactions occurring when benzalde- 

hyde is treated with the following reagents: (a) phos- 
phorus pentachloride, (6) mixture of nitric and sulfuric 
acids at o, (c) hydroxylamine hydrochloride and sodium 
carbonate, *(d) acetone and sodium hydroxide solution 
(compare Perkin and Kipping, 456), *(e) alcoholic solu- 
tion of potassium cyanide, *(/) ammonia, (g) aniline. 
* These questions are not required for study in the " short " course. 



Experiment No. 54 

ADDITION OF HYDROGEN TO AN ETHYLENE DERIVATIVE 

Preparation of Hydrocinnamic Acid (Phenylpropionic Acid) 
from Cinnamic Acid 

The 3 per cent sodium amalgam used in this experiment is 
prepared as follows: Weigh out in a dry evaporating dish or 
casserole 145 grams of pure dry mercury. Warm on the steam- 
bath to 75. Prepare 4.5 grams of sodium, free from crust and 
from the liquid which can be removed with filter paper. Cut off 
slices and immediately press them to the bottom of the warm 
mercury in rather rapid succession by means of a short moderately 
thick glass rod, drawn out to a point and bent at a short right 
angle. Use a pestle if necessary in the above operation. After 
each piece is added a somewhat violent reaction takes place. If 
the operation is conducted quickly all the sodium can be added 
before the mass solidifies. This operation must be carried out 
under the hood, using the glass door as a shield; protect the eyes 
with goggles and the hands with gloves. These precautions are ab- 
solutely necessary because pieces of burning sodium are often pro- 
jected in different directions from the dish. Break up the semi- 
solid amalgam at once and transfer it to a tightly stoppered 
dry bottle. 

Into a 250 cc. flask put 5 grams of cinnamic acid, 80 cc. of 
water containing 1.4 grams of sodium hydroxide, and 150 grams 
of sodium amalgam (3 per cent) in small portions. Shake the 
mixture well after each addition. At the beginning the amalgam 
liquefies rapidly, very little hydrogen is evolved and the solution 
becomes warm. Toward the end the amalgam does not liquefy 
at all readily and numerous bubbles of hydrogen are evolved. 
Add more water, if necessary, to dissolve any precipitate. (?) 

184 



LABORATORY EXPERIMENTS 185 

Take out a few drops of the solution, dilute, acidify with dilute 
hydrochloric acid, neutralize with and add a slight excess of 
sodium carbonate and then a drop of a very dilute solution of 
potassium permanganate. If the permanganate is decolorized 
or turns brown at once, cinnamic acid is still present and the solu- 
tion must be warmed on the steam-bath, shaken occasionally, 
and, if necessary, more amalgam added till the solution no longer 
decolorizes permanganate. This permanganate test is of great 
value for the detection of unsaturatcd compounds. (Compare 
test for "double bond/' p. 44-5.) The test cannot be applied to 
the solution when there is fixed alkali in excess because it is some- 
times masked by the formation of a green manganate. 

When the reduction is complete, pour off from the mercury, 
filter and then precipitate the hydrocinnamic acid by adding 
18 cc. of concentrated hydrochloric acid, or more, depending 
on the amount of amalgam used. The product usually separates 
as an oil which crystallizes when the solution is cooled and 
stirred. Filter off, test the filtrate for more of the product by 
adding dil. hydrochloric acid and allowing to stand, and re- 
crystallize from about 200 cc. of hot water. Yield, 4.5 grams. 

Hydrocinnamic acid crystallizes in long colorless needles which 
melt at 49. It boils at 280. It is easily soluble in boiling 
water, in alcohol, and in ether. It is volatile with water vapor, 
and solutions of it cannot be concentrated by boiling without 
loss. It is soluble i part in 168 parts of water at 20. 

The reduction of an unsaturated acid by sodium amalgam 
can only be carried out, apparently, when the double bond is 
adjacent to the carboxyl. When the double bond is further re- 
moved the reduction may often be carried out by first adding 
hydriodic acid and then reducing with zinc dust or the zinc- 
copper couple in an alcoholic solution and in presence of a 
little dilute acid. The reduction may also be effected electrolyt- 
ically. 

NOTE 

The German name for cinnamic acid is Zimmtsaure, and of 
hydrocinnamic acid, Hydrozimmtsaure. 



186 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

QUESTIONS 

1. What is cinnamic acid? 

2. How is cinnamic acid prepared? (Perkin's reaction.) 

3. Explain why the amalgam is used instead of metallic sodium. 

4. Point out what is oxidized and what is reduced. 

5. What is the white precipitate that sometimes forms toward 

the end of the reduction? Explain its formation. 

6. In the test for unattacked cinnamic acid, explain why the 

solution must first be acidified with hydrochloric acid and 
then made alkaline with sodium carbonate. How else 
could the same condition be obtained? What effect would 
the sodium hydroxide have on the test? 

7. Could the following compound be reduced with sodium 

amalgam in water: C 6 H 5 .CH : CH.CH 2 COOH? 

8. How does sodium amalgam react in an ethyl alcohol solution? 

Give an example. (Perk in and Kipping, " Organic 
Chemistry," New Ed. (IQTI), 385-6, 628.) When is amyl 
alcohol used? What advantage is there in using alcohol? 

9. What other reducing agents are used for reducing the olefine 

bond? 

10. How can benzene be reduced to cyclohexane? (Perkin 

and Kipping, 365, 623.) 

11. Discuss the hydrogenation (reduction) of oils. See C. A. 

Ellis, Journ. Industrial and Eng. Chem., 5 (1913), 95-106; 
and his book, " The Hydrogenation of Oils," published by 
Van Nostrand. 



Experiment No. 55 

REPLACEMENT OF A DIAZO-GROUP BY CYANOGEN (SANDMEYER 

REACTION) 

Preparation of />-Tolunitrile (/>-Tolylcyanide) from /-Toluidine 

Perform all the operations under the hood. Dissolve 1 2 grams 
of powdered copper sulfate crystals in 50 cc. of water in a 500 cc. 
flask by heating on the steam-bath; then add gradually, with 
continuous heating, absolution of 14 grams of powdered potassium 
cyanide in 25 cc. of water. Since cyanogen is evoked the greatest 
care must be taken not to breathe the vapors. 

While the potassium cuprous cyanide solution is further 
gently heated on the steam-bath, prepare the toluene diazonium 
chloride solution as follows: Warm 5 grams of />-toluidine with 
a mixture of 10 cc. of concentrated hydrochloric acid and 25 cc. 
of water until solution takes place. Then set the beaker in 
ice and stir in order that the toluidine hydrochloride may 
separate out in as small crystals as possible. To this ice- 
cooled mixture add gradually with good stirring a solution of 
4 grams of powdered sodium nitrite (more than i molecular 
equivalent) in 15 cc. of water until a drop of the reaction 
mixture gives a permanent blue color with starch-iodide l paper, 
or until you just notice the odor of the oxides of nitrogen from the 
excess of nitrous acid. The temperature of the mixture should 
not rise above o at any time. Pour this diazotized solution, 
in small portions during ten minutes, into the hot cuprous cyanide 
solution, with frequent shaking. A rapid effervescence occurs, 
nitrogen and some hydrocyanic acid being evolved. Heat for 
about a quarter of an hour on the steam-bath. Then distill over 
the tolunitrile with steam (see p. 158). If the solid separates 
in the condenser tube shut off the water, and after the material 

1 Prepared by soaking strips of filter paper in a very dilute solution of starch 
and potassium iodide. The papers are dried and kept in a closed bottle. 

187 



188 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

melts and flows through, slowly turn on the water again. This, 
operation must also be carried out under a hood with a good 
draft, as not only is hydrocyanic acid liberated, but a small 
quantity of the isonitrilc which is formed in the reaction pro- 
duces a disagreeable odor. Continue the distillation until no 
more of the oil passes over. 1 The nitrile solidifies in the receiver 
on cooling as a yellow crystalline mass. Cool thoroughly, 
decant off the water, and press out the substance on a porous 
tile. Distill the product from a small flask, using a short tube 
as an air condenser. Best results are obtained by distilling the 
nitrile in vacuo (p. 76). If the oil does not solidify, extract 
with ether, shake the ethereal solution with sodium hydroxide 
solution to remove the cresol (?), and then, after separating and 
drying with anhydrous sodium sulfate and evaporating the 
ether in a small flask as in the Aniline Experiment (p. 161), dis- 
till the residue directly. Boiling-point, 218 at 760 mm. and 
about 103 at 21 mm., melting-point, 29. Yield, 3.7 grams. 

QUESTIONS 

1. Give equations to show the formation of the cuprous cyanide, 

and of the nitrile. 

2. Why is it advantageous to have the toluidine hydrochloride 

separate in small crystals? 

3. Why is the solution kept cold during the diazotization? 

4. Explain the starch-iodide test for free nitrous acid. 

5. What is the formula for the isonitrile? 

6. How can you account for the presence of any cresol? 

7. How is the cresol removed? 

8. What is the Gattermann modification of the Sandmeyer 

reaction? 

9. What other derivatives can be prepared by means of the 

Sandmeyer reaction? 

10. Is it necessary to use cuprous iodide in order to prepare 

phenyl iodide from aniline? 

11. How is the />-tolunitrile converted into p-toluic acid? 

Give the " steps " in this reaction. 

12. How can you prepare aceto-nitrile (methyl cyanide) from 

acetamide? from methyl iodide? 

13. What is the action of sodium and alcohol on a nitrile? 

1 The residue in the flask should not be emptied where acid might be added 
and thus cause evolution of HCN. 



Experiment No. 66 

OXIDATION WITH POTASSIUM PERMANGANATE IN A NEUTRAL 

SOLUTION 

Preparation of Acetanthranilic Acid (0-Acetamino-benzoic Acid) 
from Acet-0-toluidide 

In a 500 cc. flask dissolve 8 grams of potassium permanganate 
and 6 grams of magnesium sulfate crystals in 250 cc. of water. 
Add 3 grams of acet-0-toluidide (Expt.46,p. 164), connect the flask 
to an upright condenser and heat slowly to boiling. Continue 
the boiling with a low flame and shake frequently until all the 
permanganate has been used up (1-1.5 hours T ). Test by 
filtering a few cc. (?) Filter the hot solution (it filters more 
rapidly when hot) of potassium acetanthranilate from the 
brown precipitate (?) with suction in a xo-cm. Buchner funnel, 
using two filter papers. If the filtrate begins to boil under the 
diminished pressure, allow air to enter by squeezing the rubber 
tube over the outlet of the suction flask until a small opening is 
made momentarily. The filtrate will probably be colored at 
first with the fine brown particles. As soon as it comes through 
water-white and clear remove the tube and transfer the brown 
liquid in the filtering flask to the flask containing the main 
bulk of the solution, then continue the filtration. If necessary, 
filter again, by gravity. What is the reaction of the filtrate 
with neutral litmus? Then carefully add to the clear colorless 
filtrate with stirring the calculated amount of sulfuric acid (as 
approximately normal solution) based upon the theoretical yield, 
to set free the acetanthranilic acid. Let stand until cold. 

1 If the permanganate has not all disappeared in this time the little that remains 
can be destroyed by adding in very small amounts through the top of the condenser 
i or 2 cc. of alcohol, or a little sulfurous acid or a sulfite. (Explain the action.) 

189 



190 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Filter off with suction the acetanthranilic acid, which is precipi- 
tated as fine white needle crystals, and wash with a little cold 
water. Test the filtrate for complete precipitation by adding 
more sulfuric acid. Melting-point, 185. Yield, 75 per cent 
of the theory. 

NOTE 

The brown stains can easily be removed from the hands and 
apparatus by means of a solution of sodium bisulfite. 

QUESTIONS 

1. What is the specific object of the magnesium sulfate? 

2. Why is it necessary that this object be attained? 

3. What becomes of the potassium and of the manganese of 

the potassium permanganate during the oxidation? 

4. How can anthranilic acid be prepared from acetanthranilic 

acid? 

5. Why cannot anthranilic acid be formed by the direct oxida- 

tion of 0-toluicline? 

6. What is meant by " blocking " or " protecting " the amino 

group? 

7. How can anthranilic acid be obtained from its potassium 

salt? 

8. What is the best method for purifying anthranilic acid? 

(Same as used for any amino acid.) 

9. How is anthranilic acid obtained from phthalic acid? Where 

is this reaction used commercially? 

10. What is the effect of hydrochloric acid on anthranilic acid? 
Is the product soluble in water? 



Experiment No. 57 

FORMATION OF AN AROMATIC ESTER FROM THE ACID AND THE 

ALCOHOL l 

Preparation of Methyl Salicylate (Oil of Wintergreen) from 
Salicylic Acid and Methyl Alcohol 

Place 17 grams of salicylic acid in a 125 cc. round-bottomed 
flask, add 30 cc. of methyl alcohol and then gradually and with 
shaking, add 4.5 cc. of cone, sulfuric acid. Add a few pieces of 
porous tiling, connect with an upright or reflux condenser, and 
heat on a steanvbath for about 2.5 hours. When the reaction has 
proceeded for some time the oil of wintergreen formed stays 
at the bottom of the flask and sometimes when stirred by the 
boiling and dripping from the condenser forms an emulsion 
which resembles a precipitate. Distill off the methyl alcohol 
over the steam-bath in the regular manner, transfer the residue 
to a separatory funnel, add about 40 cc. of water, shake, separate 
the lower layer which is the methyl salicylate, and wash it in the 
separatory funnel first with water, then with dilute sodium 
carbonate solution (Why?) and finally with distilled water. 
Separate from the water, dry over anhydrous sodium sulfate, 
and purify by distillation under diminished pressure (p. 76). 
If an emulsion is formed in the washing, allow to stand thirty 
minutes, and if it does not subside, separate the layers as well as 
possible, and then dry over anhydrous sodium sulfate. The 
turbid water layer contains only a very small amount of product. 

All the ester distills at constant temperature provided the 
pressure remains constant. The boiling-point of methyl salicy- 
late is 224 at 760 mm., and 115 (approx.) at 20 mm. Its specific 
gravity is 1.197 at - Yield, 17 grams. 

1 Compare ethyl acetate, p. 106. 
191 



192 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

QUESTIONS 

1. Define an ester. 

2. Why not use the term " ethereal salt "? 

3. What is the structure of salicylic acid? 

4. Explain why cone, sulfuric acid is used. 

5. Could dilute sulfuric acid be used? 

6. Could cone, hydrochloric acid be used? 

7. Why is not methyl sulfate formed instead of methyl salicylate 

in the experiment? 

8. What effect has an excess of methyl alcohol on the yield of 

methyl salicylate? an excess of salicylic acid? 

9. Calculate the theoretical amounts and compare with the 

amounts used. 

10. Would there be any methyl salicylate formed if the alcohol 

and acid were heated alone? 

11. Why must the methyl alcohol be removed before the mixture 

is poured into water? 

12. Why is sodium carbonate used in the washing? Could 

sodium hydroxide be used? Why? 

13. Can you suggest any other drying agents that could be used 

instead of anhydrous sodium sulfate? 

14. What is E. Fischer's method of esterification? 

15. How is Fischer's method used in the analysis of proteins? 

(Perkin and Kipping, " Organic Chemistry/' New Ed., 
(1911), 554). 

1 6. Outline three other methods of preparing esters. 

17. Compare the physical properties of acids and their esters 

(boiling-point, solubility, conductivity, etc.). 

18. Show by means of structural formulas the difference between 

the methyl ether of salicylic acid (methyl salicylic acid) 
and the methyl ester of salicylic acid (methyl salicylate). 

19. How could you differentiate chemically between the two 

compounds in No. 18? 

20. How could you separate by chemical means salicylic acid 

and methyl salicylate? 

21. How is salicylic acid prepared commercially? 

22. Discuss the chemical combination of oil of wintergreen as 

found in nature. 



Experiment No. 58 
Tannin (Tannic Acid) 

Make up 25 cc. of an approximately i per cent solution of 
tannin 1 for the first three experiments: 

1. Add a few drops of molar ferric chloride solution to about 
5 cc. of the solution of tannin. (?) Dilute i cc. of the original 
solution of tannin to 50 cc. and add a drop of the ferric chloride 
solution. (?) Repeat, using gallic acid. (?) Compare with 
section e under Phenol Experiment (p. 178). 

2. Add to the dilute solution of tannin a normal solution of 
lead acetate. Repeat, using copper sulfate. Results? 

3. Dissolve about o.i gram of gelatin in 10 cc. of warm water, 
cool, and add some of the dilute i per cent solution of tannin. 

4. Ink. Dissolve i gram of tannin in 10 cc. of hot water, 
0.5 gram ferrous sulfate in 5 cc. of hot water, and 0.05 gram of 
gum arable in 5 cc. of hot water. Cool the solutions and mix 
them. Write on a piece of paper with some of the ink, using a 
new pen. Add a few drops of ferric chloride to a little of the 
ink and write with the mixture. Compare the results in the 
two cases and explain. Put the paper away and examine the 
writing with the two samples of ink at the next exercise. Ex- 
plain. 

NOTE 

The ferrous sulfate snould contain no ferric sulfate. Use the pure 
greenish solid. If it is colored yellow or brown it has been oxidized 
in the air and is worthless. 

REFERENCE 

Holleman, " Organic Chemistry," 4th Ed. (1914), 473. 
1 This solution must be freshly prepared, since it slowly decomposes on standing. 

193 



194 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

QUESTIONS 

1. Where is tannin obtained? 

2. Is tannin a true organic (carboxylic) acid? 

3. What is Fischer's proposed formula for tannin? (For an 

extended discussion of the subject, see Emil Fischer, 
" Synthesis of Depsides; Lichen-substances and Tannin/' 
Journ. Amer. Chem. Soc., 36 (1914), 1170. For formula, 
read pp. 1193-4.) 

4. With lead acetate, does tannin precipitate lead tannate or 

a complex of lead acetate and tannin? 

5. Compare the reaction with gelatine to the use of tannin in 

tanning hides. Also with the reaction of milk in tea. 

6. Why is gum arabic used in the ink? 

7. What changes take place in the ink on the paper after 

standing? 

8. In commercial ink how is the ferrous salt kept from oxidation? 

9. As far as you can, show how the " depsides" are synthesized. 

(See Fischer's article above.) 
10. How is tannin used in dyeing? 



Experiment No. 59 

ADDITION OF A HALOGEN ACID TO AN OLEFINE 

Preparation of 7>aws-l,8-Dichlor-terpane (J-Limonene- 
dihydrochloride) from rf-Limonene 

To a 50 cc. distilling-flask with an air condenser attached add 
20 cc. of crude d-limonene l and a small amount of bright sodium. 
Distill and collect separately the fraction between 170-! 76. 
Redistill this fraction, using another small piece of clean sodium, 
and collect the portion boiling close to the boiling-point of pure 
d-limonene, 175 (uncor.). It is necessary to use pure d-limonene 
in the experiment. Destroy the sodium in the residues by treat- 
ment with alcohol before the apparatus is cleaned with water. 

Arrange an Erlenmeyer suction flask with a dropping-funnel 
as a generator for hydrochloric acid gas. 2 Place about 25 grams 
of sodium chloride in the flask and cover it with cone, hydro- 
chloric acid. From the dropping-funnel allow cone, sulfuric 
acid to drip into the mixture. Pass a slow stream of the gas 
through an empty safety bottle and then into a 250 cc. wide- 
mouthed bottle through a tube opening above a solution of 10 cc. 
of the purified d-limonene in 5 cc. of glacial acetic acid. Keep this 
solution cold by placing the bottle in a freezing mixture consisting 
of ice and a small amount of salt. The unused gas is not allowed 
to come out into the room, but is absorbed by a sodium hydroxide 
solution in a third bottle, as the bromine vapors were absorbed 
in the experiment for preparing ethylene dibromide (p. 43). 

1 If only a very crude oil is available purify it first by distilling with steam, 
drying with calcium chloride, and subjecting to an ordinary distillation. 

2 A very convenient generator for preparing hydrogen chloride from cone, 
hydrochloric acid and cone, sulfuric acid, is described by Sweeney, Journ. Amer. 
Chem. Soc. y 39 (1917), 2186. 

195 



196 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

In a short time the liquid solidifies to a crystalline mass. About 
forty-five minutes is required. It should not become appre- 
ciably discolored. Transfer it to a beaker with cold water. 
Use a few cc. of alcohol to dissolve out the residual particles and 
add this to the main portion. Dilute to 200 cc., stir well, and 
filter off the solid product with suction in a Buchner funnel 

(p. 52). 

Dissolve the product in about 45 cc. of alcohol, filter from 
any insoluble particles, and pour in a thin stream, with stirring, 
into 200 cc. of cold water. The dichlorterpane separates imme- 
diately in small white crystalline lumps. Filter again with 
suction and press out with a spatula l on the smooth side of 
a clean porous tile (p. 56) to remove the last traces of moisture. 
Since the substance evaporates very slowly when left in the 
open, it must be covered with a watch glass if allowed to stand 
any length of time before it is bottled. Tmw^-i,8-dichlorterpane 
is a white crystalline solid, melting at 50. It can be recrystal- 
lized from warm alcohol. Yield, 30 per cent of the theory. 

NOTES 

1. Since the product decomposes when standing in the presence 
of acid, the experiment should be completed in one laboratory period. 
If this is not possible, let the product remain in water. 

2. The as-form of i,8-dichlorterpane melts at 25 and is usually 
liquid at ordinary temperatures. If this is obtained instead of the 
solid /raws-form it is probably due to the use of d-limonene that 
has not been properly purified, or to allowing the temperature to go 
too high. 

3. The specific gravity of J-limonene is 0.846 at 18. 

4. The substance is also named i,8-dichlor-men thane, dipentene- 
dihydrochloride, and trans-terpm dichloride. 

5. If the dichlorterpane does not crystallize out after being 
poured into water cool the entire material in ice and then remove the 
lumps and press them out on a porous tile. If there is any of the trans- 
form present it will generally remain on top after the liquid impurities 
have been absorbed. Then recrystallize from alcohol, etc. 

1 If a steel spatula is used it should always be previously cleaned with soap to 
remove traces of dust and rust. 



LABORATORY EXPERIMENTS 197 



REFERENCES 

Cohen, "Organic Chemistry for Advanced Students," Pt. Ill 
(1918), Chap. V; Semmler, "Die Aetherischen Oele," Vol. II (1906), 
339; Stewart, " Recent Advances in Organic Chemistry," 3d Ed. 
(1918), 41-52. 

QUESTIONS 

1. What is the source of d-limonene? 

2. Name d-limonene according to the terpene system of no- 

menclature. 

3. What does the " d " in J-limonene and the " trans " in trans-i, 

8-dichlorterpane signify? 

4. Show by means of the structural formula why limonene can 

exist in both d- and /- forms. 

5. How many molecules of HC1 combine with each molecule of 

d-limonene, and how can this be shown experimentally? 

6. What is the purpose of the glacial acetic acid? What is the 

melting-point of glacial acetic acid? 

7. What is the object of the porous tile? Why not use filter 

paper? 

8. Why must the product not be left in the open? 

9. What compound is formed by the addition of HC1 to propene? 

10. Can sodium be used for purifying hydrocarbons in general? 

11. Is limonene an aromatic or hydroaromatic compound? 

Why? 

12. Of what use in terpene chemistry is the formation of the 

" hydrochlorides "? 



SYNTHESIS OF CAMPHOR FROM PINENE 

(IN FIVE STEPS) 
Experiment No. 60 

(1) Pinenehydrochloride from Pinene (Rectified Oil of Tur- 
pentine) 

Perform this experiment under the hood, or connect the 
outlet tube with the suction pump and let the water run ver? 
slowly. In the latter case pass the gases through a tube opening 
just above the surface of a 2N sodium hydroxide solution con- 
tained in a bottle, and then to the pump. 1 

Provide a 250 cc. short-neck, round-bottom flask with a 
three-holed rubber stopper, through which pass (i) a gas inlet 
tube reaching almost to the bottom of the flask, (2) a calcium 
chloride tube, (3) and a thermometer. Saturate 200 grams of 
pinene contained in this flask with dry hydrogen chloride, 
which is generated in the following apparatus. Fit up an 
ordinary liter flask or bottle with a dropping-funnel and an outlet 
tube inserted through a two-holed stopper. Connect this (i) 
with an empty wash bottle, (2) with a Woulff bottle 2 or a 250-0:. 
wide-mouthed bottle containing cone, sulfuric acid, provided 
with a safety tube 2 feet long, (3) another wash bottle also con- 
taining cone, sulfuric acid, and (4) with an empty wash bottle, 
from which the gas is led into the pinene flask. The empty wash 
bottles act as guards and prevent any danger of serious explo- 
sions in case there is back pressure in the apparatus. Use 
rubber stoppers and glass tubing throughout, joining the glass 

1 Test the apparatus for leaks with the gas under pressure before turning on 
the water. Otherwise bubbles of air may be mistaken for hydrogen chloride. 

2 A wide bottle with three apertures. 

198 



LABORATORY EXPERIMENTS 199 

tubing with as short rubber connections as possible. The two 
wash bottles with sulfuric acid are necessary for thoroughly 
drying the gas. 

The pinene flask is imbedded in a mixture of cracked ice 
and a small amount of common salt. As the reaction proceeds 
more salt may be necessary. When the apparatus is all ready 
put 500 grams of common salt in the generating flask, add 
enough cone, hydrochloric acid to cover the salt, and then allow 
cone, sulfuric acid to drop, upon this mixture from the dropping- 
funnel. The gas should be run into the pinene continuously 
at a fairly rapid rate (about two hours are necessary), care 
being taken that the temperature does not exceed 20. The re- 
action does not take place readily below o. The best tem- 
perature is about 5-i5. Sometimes it is necessary to take 
the ice away in order to allow the temperature to rise and the 
reaction to start. After the gas has been passing in for some 
time the temperature may rise to 60. This will do no great 
harm, other than to color the mixture on account of slight 
decomposition, but the temperature should not be allowed 
to stay up. A higher temperature should be avoided. A 
slower stream of gas and further cooling will soon bring the 
temperature down. The success of the experiment depends upon 
the dryness of the gas and the temperature of the reaction. 

After about two hours when no more gas is absorbed and 
the pinene has been transformed into a semi-solid mass disconnect 
the flask and close it with a good cork or rubber stopper. Cool 
it to 10 to 15 in a freezing mixture consisting of about 
two parts of cracked ice and one of salt and let it remain for 
thirty minutes or overnight (in the ice-box). In case it is left 
overnight, care should be taken that no water from the melting 
ice will get into the flask, by fastening the flask upright with a 
clamp. On the next day it must be packed again and cooled 
for an hour. Filter off the crystallized pinenehydrochloride with 
suction x and press out on a porous tile. Cool the filtrate and 
thus obtain more of the product. Now dissolve the entire 

1 It is convenient to use a flat-topped glass stopper to press down the cake 
in the Buchner funnel. 



200 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

crude product in about 80 cc. of warm alcohol contained in a 
beaker and heated on the steam-bath. It will remain milky 
white. Then cool to 5, with stirring to avoid the formation of 
a solid mass. Filter and press out as above. Yield, 100-125 
grams. The snow-white crystalline powder, which has an odor 
resembling camphor, melts at n8-i2o. This product is 
used for the next experiment. It is somewhat volatile at the 
ordinary temperature and pressure, and therefore should not be 
left uncovered for any length of time. 

NOTES 

1. Arrange your time so that the experiment may be started at 
the beginning of a laboratory period. The pincnehydrochloride should 
be recrystallized from alcohol the same afternoon or on the following 
day, since it decomposes slowly on standing. If it does not crystallize 
after the gas has been run in for i\ hours, the pinene used probably 
contained moisture or was otherwise impure, or the temperature was 
too low. 

2. Perfectly pure and stable pinenehydrochloride which melts 
at 125 can be obtained by crystallization from petroleum ether, but a 
large amount of the substance is lost by this method. 

3. At one time pinenehydrochloride was known as " artificial 
camphor/' on account of its odor. Now, however, this is a 
misnomer, since camphor itself can be synthesized. 

4. Rectification of Oil of Turpentine. Pinene (boiling-point, 
155) is the chief constituent of the oil of turpentine. It is obtained 
fairly pure by distilling the oil in a flask with metallic sodium and 
using a Young's pear fractionating column or still-head (Fig. 4, 
p. 25). The portion going over between 154 and 160 consists 
almost entirely of pinene. For this experiment use 300 cc. of crude 
pinene and about 4-5 grams of sodium. 

5. The brown resinous mass remaining in the flask is treated 
with alcohol to destroy any unattacked sodium before water is added 
and then the flask is cleaned. 

6. Save a specimen of at least i gram of each of the products in 
the synthesis of camphor from pinene, and hand them in. 



LABORATORY EXPERIMENTS 201 



GENERAL REFERENCES FOR STUDY 

Stewart, " Recent Advances in Organic Chemistry," 3d Ed. 
(1918), Chap. Ill; and Cohen, " Organic Chemistry for Advanced 
Students," 2d Ed., Pt. Ill (1918), Chap. V; and Semmler, " Die 
Aetherischeii Oele," Vol. II (1906). 

QUESTIONS 

1. Outline the terpene system of nomenclature and write all the 

reactions in the synthesis of camphor from pinene on this 
basis, using only the skeleton formula. 

2. Discuss Baeyer's Strain Theory. 

3. Review the properties of the olefines as shown by their reac- 

tions when treated with (i) halogens, (2) halogen acids, (3) 
hydrogen in presence of colloidal platinum or finely divided 
nickel (at high temperature), (4) hypochlorous acid, 
(5) nitrosyl chloride, (6) cone, and fuming sulTuric acid, 
(7) ozone, (8) potassium permanganate, (9) heat alone, or 
with strong acids and pressure. 

4. What addition products are used for the identification of the 

terpenes? 

5. What compounds are formed when pinene is treated with 

moist hydrochloric acid, and particularly with alcoholic 
sulfuric or nitric acids? 

6. Is pinene regenerated when pinene hydrochloride is boiled 

with "alcoholic potash " or potassium phenolate? What 
does this indicate? 

7. Can sodium be used in general for the purification of hydro- 

carbons? 



Experiment No. 61 
(2) Camphene from Pinenehydrochloride 

In a 400 cc. round-bottomed flask melt 190 grams of phenol l 
and then add 75 grams of potassium hydroxide 2 (crushed). The 
mixture becomes heated spontaneously and the alkali dissolves. 
Shake. Warm, if necessary, to produce complete solution. 
Now connect the flask with a condenser for distillation, insert a 
thermometer with the bulb in the neck (not in the liquid), and 
carefully heat over a metal gauze to distill off the water formed 
in the reaction. A small amount of phenol also goes over. 
After the temperature reaches 150 exchange the water con- 
denser for an air condenser. When all the water has been 
distilled off and the temperature has risen to 180, allow the 
flask to cool somewhat, disconnect, and add 100 grams of pinene- 
hydrochloride, 3 in three portions, the second and third after 
the preceding reaction has subsided. Attach an upright air 
condenser to the flask after each addition and heat carefully 
at first since there may be a violent reaction. Finally keep the 
mixture boiling for two or three hours, shaking the flask fre- 
quently. The vapors must not be allowed to rise more than 
one-half the length of the air condenser. // the heating is very 
strong, fumes will come out of the top and these will settle down and 
become ignited. If the heating is interrupted and the potassium 
phenolate is allowed to solidify the flask must be cautiously 
heated around the sides until the solid material melts before heat 
is applied at the bottom. 

1 If any phenol conies in contact with the skin apply alcohol at once. 

2 Sodium hydroxide cannot be used on account of the high melting-point of 
the sodium phenolate. 

8 Prepared in the previous experiment. 

202 



LABORATORY EXPERIMENTS 203 

Then, in order to obtain the camphene, subject the mixture 
?o distillation in the same manner as the water was distilled 
above, using an air condenser, until the temperature of the 
vapor reaches 180 (the boiling-point of phenol). At first 
pure camphene distills (i5o-i6o), later it is contaminated 
with increasing amounts of phenol. The distillation is stopped 
when a drop of the distillate entirely dissolves in dilute sodium 
hydroxide. (Why?) The distillate is then shaken in a flask with 
dilute sodium hydroxide (Why?), and cooled with ice, whereby 
the camphene solidifies in crystalline lumps. If the camphene 
does not crystallize out well from the alkaline solution, warm, 
separate and then cool. Filter with suction and wash with ice 
water, retaining the filtrate for recovering the phenol, if desired 
(see below). If a small amount of an oily constituent should pass 
through the filter paper, separate it from the remainder of the 
filtrate and add to the main portion. Heat the camphene in a 
small flask on the steam-bath until it melts. When it is liquid, and 
a good separation can be made, pour off from the drops of water 
into an Erlenmeyer flask and again melt in the same way with 
addition of a few pieces of calcium chloride, decant, and finally 
fractionate in a round-bottomed flask surmounted by a good 
fractionating column such as the apparatus of Young (Fig. 4, 
p. 25), to which is connected an air condenser. Protect the 
distilling apparatus from excessive radiation and consequent con- 
densation by surrounding it with paper or a towel. Collect the 
fraction distilling between 155 and I6O . 1 This solidifies on 
cooling to a colorless, crystalline mass. Yield, 60 grams. Pure 
camphene melts at 5i-52 and boils at 160. 

The product should be chlorine-free. Test for chlorine 
according to the directions on p. 114. If the product is not 
chlorine-free, redistill until the distillate gives no test for halogen. 

The residue in the flask contains a small amount of pinene- 
hydrochloride. 

If it is desired, the student may recover the phenol used 

1 Use only this fraction for the next experiment. The lower boiling fraction 
(around 147) contains other hydrocarbons which, if allowed to remain, apparently 
causes trouble in the crystallization of the isoborneol later on. 



204 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

in this experiment, part of which is in the main residue and 
part in the sodium hydroxide washings, by making the combined 
residues acid with hydrochloric acid and then extracting with 
ether. Dry the ether solution for twenty-four hours over anhy- 
drous sodium sulfate, decant and remove the ether in the ordinary 
way by distillation and then distill {he phenol, using a short air 
condenser. Boiling-point, 181.5 Yield, 150-160 grams. 

QUESTIONS 

1. Why is potassium phenolate used instead of potassium 

alcoholate? 

2. Why not use sodium phenolate? 

3. How is the camphene separated from the phenol? 

4. Give two reactions which show that camphene is chemically 

different from bornylene. 

5. What is formed when camphene is oxidized with chromic acid? 



Experiment No. 62 
(3) Isobornylacetate from Camphene 

To a solution of 50 grams of camphene l in 125 cc. of glacial 
acetic acid contained in a flask, add a mixture of 2 cc. of cone, 
sulfuric acid and 3 cc. of water. Warm on the steam-bath 
to 5o-6o (thermometer in the flask) for 2.\ ' hours, with 
frequent shaking. The reaction product separates in two layers 
at first which finally disappear after heating. 

Transfer the reddish-colored solution of the ester to a large 
beaker, rinse the flask with 100 cc. of water and add this to the 
beaker. Neutralize with, powdered sodium carbonate crystals 
(about 300 grams). Separate and dry the ester with calcium 
chloride, and then fractionate in vacua. At 12 mm. pressure 
the first runnings up to 95 contain some camphene; the main 
portion then distills between 95 and 105 at 12 mm., chiefly 
ioo-io2. Yield, 60 grams. Isobornyl acetate is a colorless 
liquid which smells like valerian. Specific gravity, 0.9905 at 
15. Boiling-point, 102 at 12 mm.; io6-io7 at 15 mm. 

QUESTIONS 

1. Explain the use of the sulfuric acid. 

2. Why is the crystalline sodium carbonate preferred to the 

anhydrous sodium carbonate or to sodium hydrogen 
carbonate? (Compare heats of solution.) 

3. Why is the isobornyl acetate so carefully purified? 

1 Experiment No. 61. 



205 



Experiment No. 63 
(4) Isoborneol from Isobornylacetate 

The isobornylacetate is hydrolyzed (saponified) with potas- 
sium hydroxide and converted into isoborneol as follows: In a 
250 cc. flask dissolve 50 grams of isobornylacetate 1 in a solution 
of 100 cc. of alcohol and 20 grams of potassium hydroxide, and 
heat to boiling for three hours under reflux condenser on the steam- 
bath. Pour the solution into cold water. The isoborneol separates 
as a white or light yellow solid. If it remains as an oil or a 
semi-solid mass, place the beaker in ice and stir with a mechanical 
stirrer 2 for J to 2 hours. The isoborneol gradually becomes white 
and crystalline. If it does not crystallize, but remains as an oil 
or an oily lump, separate, add fresh water, and stir again. Break 
up any lumps. Or continue the hydrolysis with fresh " alco- 
holic potash " for \ to i hour. Filter off the crystals with 
suction, and wash with cold water, press out and dry on a porous 
tile. Melting-point of this crude product, 203-2O5. Yield, 
35 grams. The isoborneol thus obtained is pure enough for con- 
version into camphor, as described in the next experiment. 
Crystallized from petroleum ether, absolutely pure isoborneol 
is obtained, melting at 212 (in a closed tube, see foot-note 7, 
p. 66). 

QUESTIONS 

1. Compare the preparation of glycol from ethylene dibromide 

through the acetate. 

2. How can ethyl alcohol be prepared from ethylene? 

1 Experiment No. 62. 

2 An electric mixer such as are used at soda water fountains is excellent for this 
purpose. 

206 



LABORATORY EXPERIMENTS 207 

3. What chemical reaction of isoborneol shows that it is a 

tertiary alcohol? 

4. Why cannot a good melting-point of isoborneol be taken in 

an open tube? 

5. How does changing the water aid in the crystallization of the 

product? 

6. Is alcoholic KOH generally used for hydrolysis? (Compare 

the analysis of fatty oils, etc.) 

7. How can tertiary alcohols be prepared by the Grignard 

reaction? 



Experiment No. 64 
(5) Camphor from Isoborneol 

Perform this experiment under the hood or near the draft pipe. 
Make a mixture of 60 grains of concentrated nitric acid (sp.gr. 
1.42) and 12 grams of red fuming nitric acid (sp.gr. 1.60) in a 
250 cc. flask, cool to 2o-25, and keeping the temperature be- 
tween 2o-25, cautiously add in small amounts 30 grams of 
isoborneol. 1 Each portion of isoborneol dissolves in the acid 
with rise in temperature and evolution of nitric oxides. During 
the operation the mixture must be well stirred, shaken and 
cooled. At the end, a compound of camphor and N2Os separates 
as a slightly colored oily layer. Continue the stirring and 
shaking as much as possible for about thirty to forty minutes, 
and then, while shaking, slowly pour out the contents into some 
cracked ice in a beaker. The camphor separates out in white 
lumps. If it does not, melt the ice, separate, and add cold 
water to the camphor layer. It will then crystallize out, espe- 
cially on cooling. Filter with suction and wash with ice water. 
This crude product melts at about 168 and contains some 
oxides of nitrogen. In order to purify the camphor treat it in 
a 500 cc. flask with a dilute solution of 3 grams of sodium hydrox- 
ide and 5 grams of potassium permanganate, and then distill 
with steam through an air condenser 2 into a wide-mouthed bottle 
which is cooled in cold running water. Dry the purified pro- 
duct on a porous tile. It should be perfectly white, and melt at 
i72-i73. Yield, 21 grams. Camphor is volatile and care 
must be used to carry on all operations under good cooling. 

1 Experiment 63. 

2 The camphor separates out in a water condenser, and therefore if one is used 
the distillation must be discontinued now and then, and the camphor pushed out 
with a long rod. Otherwise it will clog the condenser. 

208 



LABORATORY EXPERIMENTS 209 

By neutralizing the nitric acid filtrate obtained above with 
sodium carbonate and distilling this with steam, about 2.5 grams 
more of camphor can be obtained. 



NOTES 

1. Do not leave the product in the open air longer than is neces- 
sary to press out on the porous plate. 

2. ^/-Camphor melts at 175, boils at 209, and sublimes at the 
ordinary temperature; sp.gr. 0.992 at 10. Camphor obtained from 
isoborneol consists of a racemic mixture. Camphor from the camphor 
tree (Laurus camphora) is dextro-rotary. 



REFERENCE AND ACKNOWLEDGMENT 

This series of experiments in the synthesis of camphor is based 
upon those given in Ullmann's " Organisch-Chemisches Praktikum" 
(1908), 230-6, and the author is glad to make acknowledgement here. 



QUESTIONS 

1. How is camphor obtained from isoborneol? 

2. Point out the asymmetric carbon atoms in camphor. 

3. Is the product obtained optically active? Why? 

4. Give several reactions which show that camphor is a ketone. 

5. How can it be shown that there is a CH2-group adjacent to the 

carbonyl group? 

6. Discuss the oxidation products of camphor. 

7. Outline Komppa's synthesis of camphoric acid. 

8. How can camphor be synthesized from camphoric acid? 



Experiment No. 65 

DIRECT OXIDATION OF A HYDROCARBON 
Anthraquinone from Anthracene 

Connect a flask containing 2.5 grams of anthracene with an 
addition tube and a reflux condenser. Pour in 20 cc. of glacial 
acetic acid and heat on the steam-bath. Prepare a solution of 
4.5 grams of chromium trioxide in a little water and add 7 cc. 
of glacial acetic acid. Add this solution in small amounts to 
the flask and continue the heating for five minutes after the 
addition of the last portion. It will not all dissolve. Pour 
the green mixture into water, and stir well. Filter off the 
precipitate with suction, wash, and dry it. Recrystallize as 
follows: Pour over the dry product in a flask no cc. of toluene. 
Connect with an upright condenser and heat carefully over a 
wire gauze to boiling for several minutes. Do not use such a 
large flame that some of the vapors come uncondensed out of the 
top of the condenser. The vapors are heavy and will settle 
down and become ignited. The solubility of anthraquinone 
is 2.56 parts in 100 parts of toluene at 100. Immediately after 
disconnecting, filter the solution through a fluted l filter paper 
in a glass funnel set in a hot-water funnel, 2 using a stirring- 
rod to direct the flow of the hot solution into the filter. When 
filtering inflammable liquids, the burner under the side tube 
must always be removed. The anthraquinone rapidly crystal- 
lizes out. It is separated with suction 3 and allowed to dry 

^eep. 128. 

2 Sec p. 128. 

3 If it is desired to concentrate the toluene solution, distill off the toluene in the 
usual way from a distilling flask. This, however, generally gives dark-colored 
crystals. 

210 



LABORATORY EXPERIMENTS 211 

between filter papers. Large well-formed crystals are obtained 
if the filtrate is allowed to cool very slowly. This can be done 
by placing the beaker in warm water and letting all cool together. 
However, the finer crystals formed by rapid cooling are more 
likely to be the purer product. Melting-point 285.5, cor - 
Yield, 2.5 grams. 

Sublime a sample of the anthraquinone as follows: Place 
a small amount of the material on an 8-cm. watch glass, cover 
with an 8-cm. filter paper which has been perforated with a 
number of tiny holes, and then put another watch glass of the 
same size, convex side up, over these. Set on a wire gauze 
and place a very small flame underneath. Light-yellow crystals 
soon begin to deposit on the cold surface of the upper watch 
glass and the paper will prevent them from falling back to the 
lower one. An inverted funnel can be used instead of the upper 
watch glass. Determine the melting-point of this sublimed 
sample as well as of the recrystallized product. 



QUESTIONS 

1. Is anthraquinone a true chemical derivative of anthracene? 

2. Compare anthracene and diphenylme thane in regard to 

oxidation with chromic acid. 

3. Does anthraquinone have any aliphatic characteristics? 

Compare it with />-benzoquinone. 

4. Explain why you should expect the 9 and TO carbon atoms 

of anthracene to be more easily oxidized than the others. 

5. What naturally occurring dye is related to anthraquinone? 

6. To what is the green color of the reaction mixture due? 

(Compare question 4, Acetaldehyde Ammonia, Expt. 17, 
p. 88.) 

7. Why cannot alcohol or water be used in place of the acetic 

acid in this experiment? 

8. Why is a fluted filter paper used? 

9. Why are the finer crystals more likely to be purer? 

10. Explain sublimation. 

11. Does anthraquinone contain auxochrome or chromophore 

groups? 

12. How can anthraquinone be reconverted into anthracene? 



212 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

13. What compound is formed when anthraquonine is shaken 

with zinc dust and sodium hydroxide solution? How 
can this be changed back into anthraquinone? 

14. Discuss quinone monoxime relative to its structure and 

method of preparation from quinone, and from phenol. 

15. What are the naphtho-quinones? How prepared? 



Experiment No. 66 

NITROGEN HETEROCYCLES 
Pyridine 

1. Dissolve a few drops of pyridine in pure ammonia-free 
water and test its reaction with neutral litmus. 

2. To an aqueous solution of pyridine add a drop or two of 
i molar ferric chloride solution. (?) 

3. Mix i cc. of pyridine and 0.9 cc. of methyl iodide 1 in an 
ordinary No. 2 test-tube supported in a rack. Stir with a ther- 
mometer. A vigorous reaction sets in and a yellowish solid is 
formed. Note the temperature as the reaction continues. 
It may become so hot that the product melts. Recrystallize 
the product by adding 5 cc. of absolute alcohol and heating the 
tube in warm water until solution takes place, and then allow 
to cool. Filter with suction and wash the crystals with a small 
amount of cold absolute alcohol. The crystals are usually in the 
form of flat pencils which are sometimes aggregated in rosettes. 
They very slowly deliquesce. Melting-point, 117. 

Test the solubility of a small portion of the recrystallized 
product in water. To this solution add a drop of silver nitrate 
solution. Is there an immediate precipitate? What is it? 
Account for it. 

Quinoline 

1. Test the solubility of quinoline in water. Does the 
aqueous layer react alkaline toward litmus? 

2. Add a little hydrochloric acid to a few drops of quinoline 
in Water. (?) 

1 Methyl iodide is somewhat poisonous. Be careful not to breathe its vapors or 
get it on the skin. 

213 



214 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

3. To a hydrochloric acid solution of quinoline add a solu- 
tion of potassium dichromate. (?) 

QUESTIONS 

PYRIDINE 

1. Write the equation to show the substances formed in the 

condition of equilibrium when pyridine is dissolved in 
water. 

2. Explain the action of the aqueous solution of pyridine on 

ferric chloride. What is the precipitate? 

3. What type of substance is formed by the reaction between 

pyridine and methyl iodide? Write its structure. 

4. Explain the action of silver nitrate on the aqueous solu- 

tion of the pyridine iodmethylate (or methiodide). Com- 
pare with ethylammonium chloride used in a previous 
experiment (under Methyl Amine, p. 121). 

5. What is formed when the pyridine iodmethylate is treated 

with potassium hydroxide? 

6. What is formed when the pyridine iodmethylate is heated 

alone to 300? Compare with the preparation of o- and 
/>-toluidine from methyl aniline. 

7. How could you tell experimentally when a substance con- 

tains a tertiary nitrogen atom as in pyridine and when it 
contains a secondary nitrogen atom as in pyrrole, coniine, 
etc.? 

8. Look up the formulas for nicotine, coniine, tryptophane and 

indigo. What nitrogen heterocycles do they contain? 

QUINOLINE 

9. Write the structures of the compounds formed when quino- 

line is treated with hydrochloric acid, and this solution 
with potassium dichromate. 

10. Why does the quinoline dissolve in dilute hydrochloric acid? 

11. How can quinoline be prepared synthetically? 

12. How does isoquinoline differ from quinoline? 

13. Look up some alkaloids which contain the quinoline nucleus; 

also the isoquinoline nucleus. 



PART H 

ORGANIC COMBUSTIONS 



FOREWORD 



THE determination of carbon and hydrogen and of nitrogen 
in organic substances is very important because it is fundamental, 
and yet, in spite of its importance, the operations are not always 
as successful as they should be, and are often regarded in organic 
laboratories as a somewhat " necessary nuisance," and as F. G. 
Benedict says, 1 " exasperatingly vexatious." It is practically 
impossible to find a commercial laboratory that will undertake 
the task, and usually one must set up his own apparatus and 
attend to it himself unless he is so fortunate as to be located 
in a large research laboratory where someone is employed for 
this sole purpose. 

Organic combustions, as the operations are commonly called, 
will continue to be more or less difficult, since some variation must 
be added in the case of each individual substance. Combustions 
should be considered as a means to an end, not the end in itself, 
and therefore the methods should be so clearly and exactly defined 
that they can be carried out with the greatest possible accuracy 
in the minimum amount of time and with the smallest amount 
of energy. If all the mechanical details and the more useful 
forms of apparatus are adequately described and the pitfalls in 
manipulation pointed out, there is no good reason why anyone 
with a knowledge of and skill required in ordinary quantitative 
analysis should not be able to master the method and obtain 
good results from the very beginning. Accordingly, if the direc- 
tions in the following pages come anywhere near accomplishing 
this end, the hopes of the author will be realized. 

The methods selected for description are the outgrowth of our 
experience covering several years. Like most workers in the 
subject the author has taken the liberty of describing some of his 
own modifications, especially in apparatus, and he is willing to 
assume the responsibility for the direct statements made herein. 
1 " Elementary Organic Analysis," Preface. 
216a 



216b FOREWORD 

Where he has not been very familiar with a certain procedure or 
with certain kinds of apparatus he has tried to show that lack 
in the wording of the text. The descriptions ordinarily refer to 
work on the common organic compounds usually met with in 
laboratory practice. 

It is believed that many of the difficulties in carrying out an 
organic combustion arise from the fact that the operator, as is 
very natural, is not thoroughly familiar with the apparatus and 
its possibilities. For this reason, the apparatus has been very 
carefully described, and many of those little " kinks " which are 
very helpful but not always available in writing are also added. 
Lest the student lose track of his work on account of the length 
of some of the descriptions and notes, he is referred to the 
important " Topical Outline of General Method of Procedure/' 
which is a concise summary of the necessary operations arranged 
to save both time and energy. It must be remembered that you 
cannot run a combustion just by keeping a set of directions 
beside your apparatus. You must study the method in detail. 
Then the topical outline will help bridge the gaps. 

The author has tried to give due credit to the proper authori- 
ties in special cases by numerous references in appropriate places. 
Acknowledgments are hereby gladly made to such standard 
works as: 

Gattermann's " Practical Methods of Organic Chemistry "; 
W. A. Noyes' " Organic Chemistry for the Laboratory "; 
Sudborough and James' " Practical Organic Chemistry "; 
Cohen's " Practical Organic Chemistry "; 
F. G. Benedict's " Elementary Organic Analysis "; 
Dennstedt's " Anleitung zur vereinfachten Elementaranalyse." 

The author also wishes to extend his grateful thanks for many 
helpful suggestions to his colleagues, especially Professors John 
M. Nelson, H. T. Beans, and Harold A. Fales, and to his former 
students and co-workers in the organic laboratory at Columbia 
University, who have borne with him in his efforts to standardize 
organic combustions and to make them more easy and fruitful. 

HARRY L. FISHER 

COLUMBIA UNIVERSITY, NEW YORK, 
June, 1919. 



DIVISION A 

THE DETERMINATION OF CARBON AND HYDROGEN 

I. Historical 1 Introduction 

In the year 1781 Lavoisier, working on the theory of combus- 
tion, established with a fair degree of accuracy the quantitative 
relation of carbon and oxygen to carbon dioxide, and of hydrogen 
and oxygen to water, and also showed that carbon dioxide and 
water were the sole products of the combustion of organic sub- 
stances such as " spirit of wine/' oil, wax, sugar, and resins. 
In 1784 he burned weighed portions of some of these organic 
substances in a known volume of oxygen, and collected the 
gaseous products in a bell-jar over mercury. These gaseous 
products he analyzed by volume, absorbing the carbon dioxide 
in a potash solution, and measuring the residual oxygen. He 
then calculated the weight of the water indirectly, and in this way 
he was able to determine the composition of the substance. 2 For 
the more difficultly combustible substances he used, instead of free 
oxygen gas, mercuric oxide and manganese dioxide, which give 
up oxygen when heated. 3 Thus he laid the very foundations of 
elementary organic analysis. 

1 Dennstedt has given us an excellent detailed account of the historical develop- 
ment of organic combustions in his article, " Die Entwickelung dcr organischen 
Elementaranalyse," in Ahrens' " Sammlung chemischer und chemisch-technischer 
Vortrage," IV (1899), 1-114. The article also contains a very complete bibliog- 
raphy. 

2 Ladenburg, " History of Chemistry," trans, by Dobbin (1899), 289. 

3 Ernst von Meyer, " A History of Chemistry," trans, by George McGowan, 
3d English edition (1906), 410-2; Armitage, "A History of Chemistry," (1906), 
54. Dennstedt, on pages 2 and 3, of his history mentioned above, gives a detailed 

217 



218 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Gay-Lussac and Thenard, 1 in 1810, extended Lavoisier's 
work and modified the method of burning the substance by 
mixing it with a known weight of potassium chlorate. The 
mixture was worked into a paste with water and formed into 
pellets, which were dried in an air-bath and dropped into a 
hot vertical tube. The gases given off were collected over 
mercury and analyzed as in gas analysis. The results obtained 
were considered as accurate as the best mineral analyses known 
at that time. Violent explosions often occurred in this method, 
and Berzelius 2 in 1817 made a marked improvement, which 
reduced the possibility of an explosion to a minimum. He 
mixed the organic substance with potassium chlorate and a 
large amount of sodium chloride, and then gradually decom- 
posed this mixture by heating in a horizontal tube. He was 
the first to pass the gases through a straight tube contain- 
ing fused calcium chloride, and thus he obtained directly the 
amount of water absorbed by weighing the tube before and 
after the combustion. He also determined the carbon dioxide 
directly by weight. For this purpose he used solid potassium 
hydroxide which was contained in a small glass vessel. It 
was weighed before, and after standing in the bell-jar for twenty- 
four hours, it was weighed again. It was no longer necessary 
to take into account the residual oxygen. 

Cupric oxide was introduced as the oxidizing agent by 
Gay-Lussac 3 in 1815, and its general use thenceforth was 
established. 

account of the method with illustrations of the apparatus, used by Lavoisier. 
Compare H. Meyer, " Analyse und Konstitutionsermittelung organischer Ver- 
bindungen," 2. Auflage (IQOQ), 146-53- 

A short history of organic combustions is also given in Lassar-Cohn's " Arbeits- 
mcthoden," Allgemeiner Teil, Vierte Auflage (1906), 274-5. 

For early work and analyses, see the following books by Emil T. Wolff, which 
are replete with examples and references, although no description of the methods 
is given; "Quellen Literatur der theoretisch-organisher Chemie" (1845), 18-26; 
and " Vollstandigc Uebersicht der Elcmcntar-analytischen Untersuchungen organ- 
ischer Substanzen" (1846). The author is indebted to Prof. F. B. Dains for 
Wolff's work. 

l Dennstedt, 9; Armitage, 129. 

2 Dennstedt, 10-11; von Meyer, 412. 

8 Dennstedt, 12; von Meyer, 413; Armitage, 139. 



ORGANIC COMBUSTIONS 219 

The U-form of tube for calcium chloride appeared in 1822, 
being first used by Bussy. 1 

The whole procedure of organic combustions was put upon a 
firm basis by the very careful and painstaking work of Justus 
von Liebig, who improved the details and simplified the deter- 
mination of carbon dioxide by the introduction of a convenient 
bulb-shaped apparatus the Liebig potash bulb. 2 

For many years Liebig's outline was the standard. Modi- 
fications were introduced, especially in the manner of heating 
the tube. He had used a charcoal furnace. This was replaced 
first by gas furnaces and now by electric combustion furnaces. 
Oxygen 3 was used instead of air in some instances. Soda lime 
was first used in 1858 by Mulder. 4 It absorbs carbon dioxide 
more rapidly than the potassium hydroxide solution and is more 
convenient to handle. The chief modification was brought out 
by Kopfer 5 in 1876, who used platinum black, and later platin- 
ized asbestos, as a catalytic oxidizing agent, burning the sub- 
stance in a stream of oxygen, without any copper oxide, etc. In 
this method the tube is shortened and only a few gas burners 
are required; furthermore, the combustion itself can be car- 
ried out in a much shorter time, and many organic substances 
which could not be properly burned by the older method could 
be burned completely. Kopfcr's method was improved by 
F. Blau, fi but has been perfected and most successful in the 



1 Journ. dc Pharm. (1822), 580; Dcnnstedt, TO. 

2 Dennstedt, 18-20; von Meyer, 413; Armitage, 149. Liebig, " Ueber einen 
neuen Apparat zur Analyse organischer Korper und iiber die Zusammensetzung 
einiger organischen Substanzcn," PoggcndorfTs Annalen, 21 (1831), i. 

Liebig published the details of the method in a pamphlet entitled, " Anleitung 
zur Analyse organischer Korper," (1837); a second edition being published in 
1853. It was translated into English by Wm. Gregory, and published in 1839 
under the title, " Instructions for the Chemical Analysis of Organic Bodies." 

3 Dumas and Stass first used oxygen in combustions in redetermining the atomic 
weight of carbon. See Dennstedt, 77. Liebig had used air in his combustion 
method. 

*Jahresber. (1858), 589; Dennstedt, 28. 

6 Ber., 9 (1876), 1377; Zeitschr. anal. Chem., 17 (1878), i; Dennstedt's 
history, 81. 

*Monatshcfle fur Chemie, 10 (1889), 357-71- 



220 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

hands or Dennstedt. 1 It requires a double inlet for two carefully 
regulated streams of oxygen. One stream goes through a short 
inner tube which contains the boat and substance, and the other 
stream goes outside this tube, and furnishes an abundant supply 
of oxygen just as the products of combustion come out of the 
inner tube and meet the catalyst. Considerable practice is 
necessary to handle the operation, but it gives excellent results. 
The platinum is " poisoned " by some substances and requires 
frequent treatment with cone, hydrochloric acid to activate it. 

Another method, which was being developed at about this 
time but which has not yet seen its full development, is the 
combustion of the substance in a bomb with oxygen under 
pressure. 2 There have been many limitations in experimenting 
with this method, but these are gradually disappearing with the 
perfecting of the bombs for calorimetric work, and the present 
author feels that the day will soon come when the variations in the 
burning of each individual substance will no longer cause any 
difficulty, since it will be possible to have a bomb in which any 
substance can be burned within a few seconds under the same 
general conditions, and connections arranged for the absorption 
of both water vapor and carbon dioxide in the usual manner. 

The use of platinum as a catalyst heated by a burner outside 
a combustion tube naturally led to the electrical heating of the 
platinum. This method has been shown to be rapid and very 
efficient, but the apparatus is not generally available. It was 
first described by Morse and Taylor 3 in 1905, and is given in 

1 Dennstedt, " Anleitung zur vereinfachten Elementaranalyse," (1903); Dritte 
Auflage (1910). 

Also, H. Meyer, " Analyse und Konstitutionsermittelung organischer Ver- 
bindungen," 2. Auflage (1909), 170-6; Gattermann, "Practical Methods of 
Organic Chemistry," 3d English ed. (1914), 113-29; and Sudborough and James, 
" Practical Organic Chemistry," (1915), 50-5. 

2 Berthelot, Comp. rend., 114 (1892), 318; 129 (1899), 1002; Ztschr. anal. 
Chem., 40 (1901), 124; Hempel, Ber., 30 (1897), 202; Zuntz and Frentzel, Ber., 
30 (1897), 381; Langbein, Ztschr. angew. Chem., Year 1900, 1227, 1259; and 
Year 1901,516. 

The method is also described in the catalogue of the Emerson Fuel Calorimeters 
(1915), 17-23. 

3 Morse and Taylor, Amer. Chcm. Journ., 33 (June i, 1905), 591; and Morse 
and Gray, Amcr. Chcm. Journ., 35 (1906), 451; and almost at the same time by 



ORGANIC COMBUSTIONS 221 

detail in Morse's " Exercises in Quantitative Analysis/' (1905), 

537-45- 

All these combustion methods require from 0.2-0.5 r am of 
substance for each determination. Oftentimes such an amount is 
not available, and on this account, Prcgl l devised a scheme by 
which it is possible to make a complete analysis for carbon 
and hydrogen on only 0.005 gram of the substance. Platinum 
as the catalyst or cupric oxide on asbestos are used in a tube 
about 20-40 cm. long. A special balance 2 is required. The 
method is spoken of as micro-combustion in contradistinction 
to the ordinary method, which is termed macro-combustion. 

In 1913 Bekk 3 published a modification of Dennstedt's 
method using cerium dioxide as the catalyst instead of platinum, 
and by using a long train of the catalyst (30 cm. of the tube 
filled with cerium dioxide deposited on asbestos) and by placing 
the substance in a special small tube inside the larger com- 
bustion tube he was able to do away with Dennstedt's com- 
plicated double inlet. He claimed even greater rapidity for his 
method over Dennstedt's, and furthermore showed that the 
cerium dioxide was not only an excellent catalyst, but also that 
it was much cheaper and not " poisoned " by the common 
materials that destroy the catalytic action of the platinum. 

Carrasco, Atti R. Accad. del Lincei Roma [5] 14, II, 608-18 (Dec. 3, 1905); Chem. 
Central. , 1906 (I), 699-701. See also Bretau and Leroux, Com p. rend., 145 (1907), 
524-6, Chem. Central., 1907 (II), 1653. 

1 Pregl, " Die quantitative Mikroelementaranalyse organisrhcr Substanzen," 
in Abdcrhalden's " Handbuch der Biochemischen Arbcitsmethoden," V (1912), 
1307-32. 

Other references on micro-combustions: Dubsky, Chem. Zlg., 40 (1916), 
201-3; Rinkes, Chem. Wcekblad, 13 (1916), 800-3; Fisceman, Rend. acad. sci. 
(Napoli), 22 (1916), 31-8; and Noorduijn, " An electric furnace for micro-ele- 
mentary analysis," Chem. Wcekblad, 14 (1917), 1131-5. 

2 Pregl describes the Kuhlmann balance used by him in his article mentioned 
above. See also Emich, " Micro-balances and their application in chemical 
analysis,'' Natitrwissensihajten, 3 (1915), 693-8. 

That an ordinary sensitive balance can be used, provided the investigator can 
use as much as 0.012-0.022 gram of substance, has been shown by L. E. Wise, 
" A simplified micro-combustion method for the determination of carbon and 
hydrogen," Journ. Amer. Chem. Soc., 39 (1917), 2055. 

*Ber., 46 (1913), 2574- 



222 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Professor Marie Reimer, 1 in an article entitled, " On Rapid 
Organic Combustions/' in 1915, combined the good points of the 
old Liebig method and of Bekk's method and showed that copper 
oxide and cerium dioxide could be used together advantageously 
for the rapid determination of carbon and hydrogen. 2 The 
technique of the method was improved by Levene and Bieber. 3 
The copper oxide is added to oxidize any products of incomplete 
combustion, like carbon monoxide, if they happen to get beyond 
the catalyst or in case the supply of oxygen is momentarily 
used up. This is the method outlined in the following pages. 

The use of alumina 4 as the absorbent for water in place of the 
time-honored calcium chloride has only recently been described. 
It is believed that it has several advantages over calcium chloride, 
for example: (i) it is a better absorbent for water/ 7 (2) when it 
has absorbed water it does not crystallize and " freeze " to the 
walls of the absorption bottle, (3) it does not require " soaking " 
with CO2 before using, and (4) the same bulk of material has 
less weight. Its chief advantage over phosphorus pentoxide is 
that it does not liquefy when it absorbs water; and over cone, 
sulfuric acid, that it is a solid and therefore readily handled 
and produces no appreciable back pressure. 

In the general description which follows, it is assumed 
that the substance to be analyzed is a solid and contains no 
other elements than carbon, hydrogen and oxygen. Further on, 
the manner of dealing with substances containing in addition 
nitrogen, the halogens, sulfur, phosphorus, etc., is discussed. 

Before taking up the method in detail it seems not inappro- 

1 Journ. Amer. Chcm. Soc., 37 (1915), 1636-8. 

2 The presence of the copper oxide obviously makes it impossible to estimate 
halogen or sulfur at the same time as the carbon and hydrogen, as has been worked 
out by Dennstedt. 

3 Journ. Amer. Chcm. Soc. 40, (1918), 460. 

4 Presented by the author at the Cleveland meeting of the American Chemical 
Society, September, 1918. 

6 That is, as compared with the ordinary " anhydrous " granular calcium 
chloride. Compare, A. T. McPherson, " Granular calcium chloride as a drying 
agent," Journ. Amer. Chcm. Soc., 39 (1917), 1317-9; and Dover and Marden, 
" A comparison of the efficiency of some common desiccants," ibid., 39 (1917), 
1609. Also Baxter and Starkweather, ibid., 38 (1916), 2038. 



ORGANIC COMBUSTIONS 223 

priate to give the following quotation from Liebig's original 
directions, as translated by Gregory : l 

" The essential conditions for performing a good analysis are 
the greatest accuracy in weighing and the strictest conscientiousness 
in the execution of all the preparatory steps of the process. Let 
us Hot flatter ourselves that we can obtain an accurate result if any- 
thing be neglected that can secure it. All the time and labor we 
bestow are thrown away, if we omit any one of the precautions which 
are recommended" 



II. List of Apparatus and Chemicals Required for the Deter- 
mination of Carbon and Hydrogen 

Apparatus 

1. Electric combustion furnace (p. 230). 

2. Electric pre-heater (pp. 228-9). 

3. Tank of oxygen with gauges and iron stand (p. 225). 

4. Pyrex combustion tube, 76 cm. long and 15 mm. inside 

diameter, for combustion furnace (pp. 231-2). 

5. Pyrex combustion tube, 36 cm. long and 15 mm. inside 

diameter, for pre-heatcr (p. 228). 

6. Asbestos paper for lining trough of the furnace and of the 

pre-heater (pp. 229, 231). 

7. Copper gauze, 40 mesh, i square foot (pp. 228, 235-6). 

8. Copper wire, No. 16, 3 feet long (pp. 228, 235). 

9. Bubble counter or gas bubble indicator (p. 227). 

10. Six red rubber stoppers, one holed; four of them size i or 

o, depending upon diameter of combustion tube; and two 
for calcium chloride tube connections (pp. 228, 242, 245). 

11. Rubber pressure tubing (pp. 227, 230, 244). 

12. Two U-tubes, with ground-glass stoppers, 12.5 cm. (5 inches) 

(p. 229). 

13. Two Fisher absorption bottles (new style) (p. 237). 

14. One calcium chloride tube, as a guard (p. 245). 

15. One small bottle for palladious chloride solution (p. 245). 

1 " Instructions for the Chemical Analysis of Organic Bodies (1839), 3. 



224 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

16. Glass tube for palladious chloride bottle (p. 245). 

17. One porcelain or quartz boat (p. 236). 

18. One special weighing tube, boat tube (" piggie ") (p. 251). 

19. Two quartz dishes, 7.5 cm. in diameter (p. 238), or one large 

one 11.5 cm. in diameter, depending upon conditions for 
heating. 

20. Crucible tongs. 

21. One pair of pliers. 

22. Desiccator. 

23. Six pine splinters, 5 to 6 inches, as aids in filling and empty- 

ing the absorption bottles (pp. 240 (foot-note), 245). 

24. One pair of forceps (long and narrow, curved near the end, 

somewhat like those used in biological work) for handling 
the cotton, and for use in filling and emptying the absorb- 
tion bottles (p. 240). 

Chemicals 

1. 35 grams soda lime, 20 mesh, 2 per cent water (about one fill- 

ing of U-tube (p. 229) and absorption bottle) (p. 243). 

2. 10 grams soda lime, 12 mesh, 15 per cent water (about one 

filling of absorption bottle) (p. 243). 

3. 100 grams aluminium chloride, crystals (AlCla.6H2O) (p. 238). 

4. i ounce of absorbent cotton. 

5. 5 grams cerium nitrate (p. 234). 

6. 120 cc. pumice, 12 mesh (pp. 234, 238). 

7. One vial stop-cock grease, E. & A. (p. 229). 

8. Cone, sulfuric acid for bubble counter and desiccator. 
Q. 100 grams cupric oxide, wire form (p. 236). 

10. 20 cc. palladious chloride solution (p. 245). 

III. Topical Outline of the General Method of Procedure 

1. Set up the electric combustion furnace (p. 230). 

2. Select the combustion tube, and if necessary cut to proper 

length and " round " the edges (p. 231). 

3. Prepare the pumice and cerium nitrate mixture and place 

in the tube (p. 234). 



ORGANIC COMBUSTIONS 225 

4. Get ready the oxygen apparatus, pre-heater, and purifying 

train (pp. 225-30). 

5. Complete the preparation of the cerium dioxide on pumice 

in the tube (pp. 234-5). 

6. Prepare the guard tube for protecting the combustion tube 

when the absorption train is not attached (pp. 246-7). 

7. Prepare the rolls of copper gauze (p. 235), the copper wire 

with hook, and fill the remainder of the combustion tube 
(p. 236). 

8. Make the preliminary heating (" glowing out ") (p. 246). 

9. During the preliminary heating, prepare the entire absorption 

train (pp. 236-46). 
10. Run a blank determination (p. 246), and weigh out the 

sample of dry substance (pp. 250-3). 
n. The combustion proper (p. 253). 

12. Calculate the results (p. 257). 

13. Run a " check " determination (p. 256). 

IV. The Apparatus and How to Put it Together with Notes 
on Manipulation 

1. Tank of Compressed Oxygen with Stand and. Pressure 
Gauges. The combustion is carried out in oxygen, which is most 
conveniently supplied in a tank or cylinder, equipped with the 
usual gauges, 1 and supported in an iron stand (see Fig. 14, p. 226, 
and Fig. 16, p. 233). The large gauge registers the pressure 
in the cylinder and the small one registers the pressure at which 
the oxygen is delivered. This delivery pressure is regulated by 
means of a thumbscrew which holds a spring in place upon an 
internal diaphragm. A small stop-cock is added beyond this 
gauge in order that the gas supply can be regulated further or 
shut off quickly when necessary. The operating pressure is 
generally from i to 4 pounds, but this varies greatly with the 
resistance offered throughout the combustion system. It is 

1 While this book is being published, Prof. S. W. Parr has described " A needle 
valve with delicate adjustment for high-pressure gases," Journ. Ind. and Eng. 
Chem., 11 (1919), 768, by means of which the gas can be delivered directly from the 
cylinder without the use of gauges. 



226 LABORATORY MANUAL OF ORGANIC CHEMISTRY 




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ORGANIC COMBUSTIONS 



227 



regulated in accordance with the gas bubbling. Ordinarily 
the gas bubbles should come through the bubble counter so 
fast that they can just be counted, about three to four a second. 
This rate of course varies with the substance being burned. 

2. The Bubble Counter. 1 The bubble counter (Figs. 15 and 
16) is placed next to the supply of oxygen and is connected with 
the outlet from the pressure gauges by means of heavy-walled rub- 
ber pressure tubing. Only a very small amount of concentrated 
sulfuric acid is required in this apparatus, usually not over 0.3 cc. 2 
A larger amount of the acid gives irregular bubbling on account 




BUBBLE 
COUNTER 



FIG. 15. 

of the depth of the liquid. The liquid is run in through a small 
tube or dropped into the outlet tube of the apparatus. The 
apparatus is constructed in such a manner that this small 
amount of sulfuric acid cannot run out, even though it be turned 
upside down, and cannot flow back in case of back pressure. 3 

1 Also called " Gas bubble indicator." 

2 About 15 drops as counted when dropped from the tip of a small tube, drawn 
out to a thin-walled opening, i mm. in diameter, such as would be used for filling 
the apparatus. 

3 If some other style of bubble counter is used which is not so constructed that 
provision is made for possible back flow, then arrangements should be made for 
attaching an inlet tube containing a bulb like a small pipette which will act as a 
reserve reservoir for the liquid in case of back pressure. 



228 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

As stated in connection with the pressure of oxygen under 
the preceding heading the rate of gas bubbling should ordinarily 
be so fast that the bubbles can just be counted, three to four a 
second, although this rate will vary more or less with different 
substances. 

The object of the bubble counter is not only to give one 
an idea as to how fast the gas is passing into the apparatus, 
but also to show a comparison between the amount of gas enter- 
ing the train and the amount of gas leaving the system through 
the palladious chloride solution (see No. 5c, p. 245). This will 
be discussed in detail later (pp. 245, 254). 

The bubble counter is connected with the glass tube in the 
pre-heater by means of a good red rubber stopper. On the 
side near the oxygen tank it should be supported with a clamp 
to prevent sagging of the tube in the pre-heater when it is hot. 

3. Gas Purifying Apparatus, including the Pre-heater. 
The Pre-heater. The compressed oxygen generally contains 
small amounts of impurities and it has been found that it is best 
and easiest to purify it by passage over hot copper oxide or cerium 
dioxide on pumice in a " pre-heater " before running the gas 
through the regular drying train. 1 After this treatment blank 
determinations will show that the apparatus is ready for use right 
after the preliminary heating of the combustion tube. Other- 
wise the percentage of hydrogen will be too high. 

Round off the ends of a Pyrex combustion tube, 36 cm. 
long and 15 mm. inside diameter, in a blast flame. Then put 
inside a 12 cm. roll of copper gauze or a 12 cm. layer of copper 
oxide in wire form. The roll of copper gauze or copper " spiral " 
as this is sometimes called, is made by tightly rolling a piece 
of copper gauze (40 mesh to the square inch), 12 cm. wide and 
about 18 cm. long, around a length of No. 16 2 copper wire and 
bending the projecting ends of the wire into short loops close to 
the gauze. 

'This has been found necessary when the oxygen is manufactured by electrolysis, 
as demonstrated in our laboratory by Miss Alice R. Thompson. It contains 
small amounts of hydrogen (o.j to i.o per cent). 

2 Brown & Sharpe gauge. 



ORGANIC COMBUSTIONS 229 

This tube is heated to dull redness in a 20 cm. (8 in.) electric 
furnace provided for this purpose. It consists of one of the 
sections of an electric combustion furnace, mounted like the regu- 
lar furnace itself, with trough and its own rheostat for tempera- 
ture control. In order to prevent the glass, if it should melt, 
from adhering to the trough, place under it a strip of asbestos 
paper. The ends of the glass tube are allowed to project more 
than usual beyond the furnace, since all precautions must be 
taken to prevent the rubber stoppers from burning. 

The Purifying Train. The oxygen must be freed from any 
possible traces of carbon dioxide and water, and therefore it is 
next passed through a 12.5 cm. (5 in.) U-tube l containing 
soda lime (2o-mesh size and containing 2 per cent of moisture) 
and then through another U-tube containing alumina-pumice. 2 
These U-tubes should be fitted with ground glass stoppers 3 and 
should have glass braces 4 to give strength and to prevent 
breakage. The stoppers must be greased with a good stop- 
cock grease 5 in such a way that they present a clear surface 
showing good contact. Too little grease makes a stopper stick 
or leak; too much often stops up the openings and also makes 
the stopper so loose that the gas pressure may force it out of 
the tube. Never turn a stop-cock by using only one hand. 
Use the other hand at the same time to hold the U-tube, then 
you can be sure that the stopper is in tight and that there are 
no channels. The stoppers should be kept closed when the 
apparatus is not in use. This applies particularly to the alumina- 
pumice U-tube. 

1 A small funnel of thin glass with a wide stm is very useful in filling the 
apparatus. 

2 See p. 238 for preparing the alumina-pumice. 

3 Fasten these stoppers loosely with wire or twine, otherwise, if excessive 
pressure is developed, they may be forced out and the stoppers broken. This 
causes much inconvenience. Do not use rubber bands. On account of their 
elasticity they often alter the position of the stopper after it has been set. 

4 R. Nowicki, Chcm. Ztg., 28 (1904), 622; Mclntire, Jonrn. Amcr. Chem. Soc., 
33 (191 1), 450-1 (like the ones shown in the figure). For other similar types, 
see Abdcrhalden's " Handbuch dcr Biochcmischen Arbeitsmethoden," VIII (1915), 
400-1. 

5 Do not use vaseline, since the stoppers are likely to stick. Eimer & Amend, 
N. Y., furnish a good stop-cock grease in handy soft metal tubes. 



230 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Place a wad of absorbent cotton on top of the material in 
each arm of the U-tubes to keep the stop-cocks free from dust 
particles. 

Connect the U-tubes by means of rubber pressure tubing. 
It is well to support these U-tubes by means of a clamp around 
the rubber connection. This prevents any sagging of the tubes 
in both pre-heater and combustion furnace when they are hot. 

The preparation of the aluminium oxide on pumice is de- 
scribed in connection with the absorption bottle for water 
(see 5a, p. 238). The same kind of material must be used here 
for drying the gas as is used for absorbing the water in the 
absorption train, otherwise there will be discrepancies in the 
percentage of hydrogen. 1 

Instead of the U-tubes any variety of absorption apparatus 
may be used. No weighing is necessary and therefore the shape 
docs not require consideration. The same type of absorption 
bottles as described in the absorption train can be used if desired. 

If many combustions are to be run, the purifying train 
should consist of more U-tubes, or of larger apparatus according 
to conditions. 

4a. The Electric Combustion Furnace. The multiple unit 
type of electric combustion furnace is the most convenient to 
use. 2 Each heating section is regulated by its own rheostat 
placed underneath and is fitted with replaceable heating units. 
The upper part of each section can be lifted and the tube ex- 
amined at any time during the course of the combustion. The 
maximum current requirement is from 12 to 18 amperes, de- 
pending upon the model. The units are so well insulated that 
parts of the tube may be heated to redness while other parts 
remain cool fairly close to the unit. This insulation to prevent 
loss of heat is a boon to the manipulator also because it makes it 
possible to run combustions in a small room even in summer time 

1 See, also, Morse, " Exercises in Quantitative Chemistry" (1905), pp. 340-2, 
353-4, where data are given to illustrate the difference in the absorption capacity 
of warm and of cold calcium chloride, and of cone, sulfuric acid. 

2 Multiple unit electric organic combustion furnace, Type 122-8, manufactured 
by the Electric Heating Apparatus Co., Newark, N. J., is built in accordance with 
the specifications given in this description. 



ORCxANIC COMBUSTIONS 231 

with no more discomfort than in carrying out ordinary work. 
The trough for supporting the combustion tube is made of nickel 
and therefore it does not corrode appreciably even in the high 
heat. A strip of asbestos paper is placed in this trough and then, 
if the glass melts, it will not stick to the metal and crack on 
cooling. In case the tube does crack, turn off the current and 
when the furnace is cold remove any copper oxide wire that might 
get among the wires of the heating units when the glass is 
taken away, otherwise short circuits will result later. 

The electric combustion furnace is ordinarily supplied with 
three heating sections of unequal lengths. Each of these can 
heat the tube to redness. The longest section (No. 2) l should 
be in the center. The heat regulation of the smallest section 
(No. i) should be such that when the current is on and all resist- 
ance in, the temperature should not be above 4o-5o. When 
necessary, it should be possible to keep the section of medium 
length (No. 3) at 3oo-32o, since this is the temperature 
required when the lead peroxide mixture is used in the combustion 
of substances containing nitrogen and sulfur. (See p. 265.) 

Each rheostat is generally arranged in such a way that 
when the handle is at the right all the resistance is in and there- 
fore this position gives the lowest temperature. The heat is 
increased by moving the handle toward the left. 

The temperature must be carefully watched when the coils 
of wire are red, since it gradually rises and thus may cause the 
tube to melt after a time. In a well-lighted room it is dif- 
ficult to tell the temperature by the color of the wires. How- 
ever, if you lift the upper half just a little so that the inside 
is shaded, you can then obtain a good idea of the color and be 
able to judge the temperature properly. 

The handles on the upper section should be wound with 
asbestos cord to make it possible to touch them with the fingers 
at any time. A piece of heavy white rubber tubing serves well 
in place of the asbestos cord. 

4b. The Combustion Tube and How to Fill It. For combus- 
tion tubing, Pyrex glass is generally better than Jena or Bo- 

1 The sections are numbered correspondingly on the diagram, Fig. 16, p. 233. 



232 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

hemian glass since it does not vitrefy and become opaque at the 
required high temperature. 1 Select a combustion tube of 15 mm. 
inside diameter and of such a length (about 76 cm.) that it will 
extend 3-4 cm. 2 beyond the ends of the nickel trough. 3 Usually 
this amount of extension is sufficient to prevent the burning of 
the rubber stoppers. The end next to the absorption train should 
not be so long that much water can condense since it is difficult 
to drive this water through. 

Round off the edges of the tube by gentle heating first and 
then with a blast flame, so that they will not cut the rubber 
stoppers. Do not change the bore of the tube! 

Clean the combustion tube, and fill it as indicated in the 
diagram, Fig. 16, making sure that the positions of the materials, 
etc., are in proper relation to the sections of the furnace. The 
dimensions given are for the 72 cm. (28! in.) furnace. Even 
if a longer furnace is used, the positions of the cerium dioxide 
and the boat should be relatively the same as described here, 
the extra length being taken up simply with more copper oxide 
wire. 

1 Where many combustions are to be run, a quartz tube with a transparent 
section where the boat is placed is both advantageous and economical. Levene 
and Bieber, Journ. Amcr. Chem. Soc., 40 (1918), 460. 

2 A longer extension is necessary when a gas furnace is used. 

3 Pyrex combustion tubing is cut with a narrow grinding wheel. The ordinary 
methods cannot always be used, since the expansion of the glass on heating is so 
small. Some of these methods, however, do work sometimes and are given here 
for sake of convenience. 

1. Make a short file mark at the desired length and then heat the tube at this 
point by giving a piece of twine two turns at the mark and drawing the twine up and 
down rapidly several times while the tube is held securely by another person on the 
desk with the edge for a guide. Then immediately put the tube under cold water, 
or apply a wet cloth. 

2. A second method of cutting the glass tube is to make the file mark as above 
and then heat this mark very carefully with the slanting tiny flame from a capil- 
lary tube. This tube can be made of glass, although a metal one is of course pref- 
erable. As soon as a crack is formed follow it with the tiny flame until it extends 
clear around. Do not point the flame directly at the tube, always slant it, other- 
wise the crack may extend longitudinally. 1 

3. Another method consists in winding a platinum or nichrome wire around 
the tube and then heating it to redness by means of an electric current. 

1 K.H. Parker, Journ. Amer. Chem. Soc., 40 (1918), 105, described "Anew glass cut- 
ting tool," a small gas-heated iron for which he claims excellent results. 



ORGANIC COMBUSTIONS 
n 



233 



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234 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Prepare the cerium dioxide first. Use enough pumice l of 
i2-mesh size to fill 5-6 cm. of the tube. Dissolve 5 grams of 
pure white crystals of cerium nitrate in enough water (about 
1 2 cc.) to cover the pumice in a quartz or porcelain dish. Evapo- 
rate this mixture to dryness on the steam-bath, with frequent 
stirring to prevent formation of a cake. Then transfer this 
impregnated pumice to the tube and put the asbestos wads in 
place by means of a long glass rod flattened at one end. The 
asbestos wads should not be over 0.5 cm. in width, and the 
asbestos must not be so tightly packed that the oxygen gas will 
not go through it. This can be remedied when it is in place by 
putting in tiny holes, if necessary, with a long glass rod drawn 
out to a point. Support the asbestos wads in position by using 
a roll of copper gauze, 0.5 cm. in width. This prevents them from 
crumbling and from being moved out of position by the force 
of the gas, etc. It is important for proper heating that the 
cerium dioxide be placed in the relative position shown in the 
diagram (C) and also that the end of the boat be not more than 
2.5 cm. distant, in order to prevent the formation of explosive 
mixtures of gases. Therefore the size of the asbestos wad and 
the short rolls of copper oxide gauze must not be greater than 
mentioned above. Complete the drying by heating the tube 
at a low temperature and at the same time passing a current of 
pure dry oxygen through the tube. As soon as no more mois- 
ture collects in the cool end of the tube gradually raise the tem- 
perature while the oxygen is still passing and finally complete 
the decomposition of the cerium nitrate at dull red heat. 2 
Allow to cool in the current of dry oxygen or attach a drying 
tube to the open end of the combustion tube. When hot, the 

1 Pumice is used instead of asbestos, then the material does not crumble and 
" sag." Fisher and Wright, Journ. Amer. Chcm. Soc., 40 (1918), 869. 

2 This procedure is used in accordance with the suggestion of Levene and 
Bicber, Journ. Amer. Chem. Soc., 40 (1918), 460, who found that when the decom- 
position was carried out over a gas burner the oxide was not always so good a 
catalyst as when prepared as above. 

If the material is heated too much at first some of it is driven out of the pumice 
and deposited upon the inner walls of the tube, where it will remain when dry and 
form an opaque layer. No special harm is done if this happens. 



ORGANIC COMBUSTIONS 235 

cerium dioxide is deep yellow, but this color changes to a straw 
yellow when the material is cold. Complete the preparation of 
the cerium dioxide before putting any of the other substances 
into the tube. Otherwise the copper nitrate which is formed 
may cause trouble later by slowly being decomposed and giving 
off oxides of nitrogen which are caught in the absorption train. 
The small rolls of gauze next to the asbestos need not be con- 
sidered in this. Once the cerium dioxide has been prepared 
it will remain ready for use at any time provided, of course, that 
the combustion tube is kept stoppered when not in use. 

For position A prepare a roll of copper oxide gauze, 8 cm. 
long, by rolling a piece of copper gauze (40 mesh to the square 
inch), 8 cm. wide and about 18 cm. long, around a length of 
No. 16 copper wire (B. & S. gauge) and bending the short 
projecting ends of the wire into short loops close to the gauze. 
It should be rolled tightly. Let it remain in the tube overnight 
if possible and become molded to the proper shape and size. 
When oxidized it should fit the tube snugly but not so snugly 
that it sticks and cannot readily be withdrawn. After it has 
remained in the tube overnight cut off some of the gauze if 
necessary. The gauze usually is covered with more or less 
grease and dirt and if directly oxidized in the tube the inner 
walls of the glass often become coated with a black layer of 
fine copper oxide which makes the tube opaque. Therefore it 
is best to oxidize the roll of gauze (or copper " spiral " as it is 
sometimes called) in a large blast flame or over a Meker burner, 
before heating it in the tube. 

The copper oxide gauze is moved back and forth in the tube 
by means of a stout copper wire with a short hook bent at right 
angles. 

The object of this roll of gauze is twofold: In the first plaice 
it acts as an " oxidation buffer," that is, it oxidizes any gases 
that may go backward, and thus prevents them from getting 
so far back that the determination is spoiled. Furthermore, by 
its very shape, size, and position it causes the oxygen to flow 
through its interstices more rapidly than in the open spaces 
of the tube before and after and in this way tends to keep any 



236 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

unoxidized gases which may go backward from getting beyond it 
before they are completely oxidized. 

The intervening space of 12 cm. between the roll of gauze 
at A and the cerium dioxide at C is reserved for the boat B. 
As stated above (p. 234), the boat should be placed within about 
2.5 cm. of the cerium dioxide. A greater distance will allow the 
formation of explosive mixtures of oxygen and the gases from the 
substance. 

Ordinarily a porcelain or quartz boat 7 cm. long is used. 
Clean it with dilute nitric acid, heat in a blast flame and allow 
to cool in a desiccator. A longer boat is used for very light 
and fluffy materials. A boat with little compartments aids 
the burning of a substance which decomposes readily. The 
compartments prevent that portion of the substance that has 
melted from mixing with the unmelted portion. 

For weighing out sample, see p. 250. 

Beyond the cerium dioxide in space D put a 23 cm. layer of 
cupric oxide l in wire form and keep it in place with a short roll 
of copper oxide gauze E. Cupric oxide is very hygroscopic. 

The i2-cm. space at F is reserved for the lead peroxide 
mixture which is used when substances containing nitrogen and 
sulfur are burned. (See p. 265.) Otherwise it may be filled 
with copper oxide wire. 

6. The Absorption Train. The absorption train is made up 
of two absorption bottles, the first one for collecting the water 
and the second one for the carbon dioxide, and a guard tube and 
bottle of palladious chloride solution. The absorption apparatus 
selected should be one that is capable of being readily and 
thoroughly cleaned, easily filled and emptied, handled without 
difficulty, of a moderate capacity, and when filled not weighing 
over 100 grams. For carbon dioxide absorption, it should have 
two chambers which can be entirely shut off one from the other 
when the apparatus is not in actual use. It is believed that the 

1 Cupric oxide which has been used in the determination of nitrogen cannot 
be used for carbon and hydrogen since it contains some carbon dioxide, unless it 
has been heated for several hours in a stream of oxygen or in the open air. Com- 
pare foot-note, p. 284. 



ORGANIC COMBUSTIONS 237 

absorption bottle l shown in Fig. 17, fulfills these requirements. 



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FIG. 17. Fisher Absorption Bottle. 

1 Fisher, U. S. Patent 1,313,626 (1919). The bottle is manufactured by Eimer 
& Amend, New York. The forerunner of this particular bottle had no means of 
shutting off the two chambers, and the stopper was ground in to fit the top of the 
inner standing tube instead of the bottom. See Fisher, " A new form of absorp- 
tion bottle for use with either calcium chloride or soda lime in the elemental anal- 
ysis of carbon and hydrogen in organic substances," Journ. Ind. and Eng. Chem. 
8 (1916), 368. 

Other forms of absorption bottles and tubes can be found in the apparatus 
catalogues. 



238 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

The bottle is literally a U-tube turned partially inside out. 
The available capacity of the stopper and its extension tube 
is 25 cc., and of the outer chamber of the bottle, 25-30 cc., 
making a total available capacity of 50-55 cc. By way of 
comparison it is of interest to note that an ordinary 5-inch 
U-tube has a total available capacity of only 20-25 cc. 

a. The First Absorption Bottle. Aluminium oxide (alum- 
ina) is used for absorbing the water formed in the combustion. 
It is mixed with pumice to make it more porous. The use of 
alumina is described first. Following this, on p. 239, is a de- 
scription of the use of calcium chloride for the absorption of 
water. It should be borne in mind that whatever absorbing 
agent for water is used here, the same one must also be used 
in the soda lime bottle and in the drying train (compare p. 230). 

Preparation of Aluminium Oxide (Alumina) for the Absorp- 
tion Bottle. Dissolve 50 grams of hydrated aluminium chloride 
(A1C13-6H2O) in 100 cc. of warm water in a 11.5 cm. quartz 
or porcelain dish and stir in 50 cc. (about 24 grams) of i2-mesh 
pumice. 1 Boil down this mixture over a wire gauze or asbestos 
disk with a free flame. Stir well with a stout glass rod after 
most of the water has disappeared, since it foams a good deal 
and will also form a cake. The particles of pumice should be 
kept separated as far as possible. Continue the heating^ and 
stirring until there is no danger of later fusion of the hydrated 
salt and agglomeration of the small lumps of impregnated pumice. 
Transfer this material to a 7.5 cm. quartz or porcelain dish and 
heat in an electric muffle furnace to 7oo-75o c 2 until no more 
hydrogen chloride is given off. A higher temperature should not 
be used. The time can be shortened to thirty to forty-five min- 
utes if a stream of air is blown or drawn through the heating 

1 These amounts are for the first absorption bottle. Double them or make up 
a second batch in order to have enough for all requirements. On account of the 
foaming, the evaporation is best done in this larger dish. The final heating can 
also be done in this same dish, but it is too large for the ordinary muffle furnace, 
which has an opening only 10 cm. wide. 

2 Approximately these same conditions can be obtained by heating the mixture 
in the dish on a nichrome gauze at the tip of a non-luminous flame 5 cm. high, for 
ij to 2 hours. 



ORGANIC COMBUSTIONS 239 

chamber to remove the gaseous products. Traces of hydrogen 
chloride can of course be detected with the nose or by means of 
ammonium hydroxide. At the end of the heating the dishes 
should be cooled in a desiccator which has no other substance 
in it. A vacuum desiccator is convenient to use since the pres- 
sure inside from the heated atmosphere can be released with 
the stop-cock. If the heating is too long or too high the alumina 
will no longer cling to the pumice, but will drop off as a fine 
powder. It will do this to some extent under any conditions. 
According to Johnson l the alumina is an excellent drying 
agent up to the time that it has absorbed about 18 per cent 
of its weight of water at ordinary temperature. Fifty grams of 
hydrated aluminium chloride theoretically yields about 10.7 
grams of aluminium oxide, and this amount ought to absorb 
about 1.92 grams of water under ideal conditions. If we con- 
sider the average organic substance as containing about 5 per 
cent of hydrogen, then a 0.2 gram sample will yield approximately 
0.09 gram of water, and on this basis the aluminium oxide theo- 
retically ought to suffice for twenty-one combustions. In prac- 
tice the mixture can safely be used for four to five combustions. 

NOTE. Originally the author used asbestos instead of pumice in order to 
give plenty of surface, and prepared the reagent by heating 10 grams of pure 
aluminium hydroxide with 2 grams of asbestos, as described above. The aluminium 
hydroxide must be free from alkali. When mixed with neutral water it should give 
only the faintest color with phenolphthalein (compare curve on p. 1500 in article 
by Blum, " The Constitution of Aluminates," Journ. Amcr. Clicm. Soc., 35 (1913)). 
The alumina-asbestos mixture is very efficient as shown in this laboratory by 
Mr. Henry L. Faust, but it packs very readily and then it requires three to four 
hours for the complete passage of carbon dioxide through it, in some cases. The 
material can be regenerated by re-heating, but after a time the asbestos crumbles 
to a powder. Pumice was being considered in place of the asbestos when Mr. 
Geo. H. Walden suggested the use of hydrated aluminium chloride as the source 
of alumina instead of the aluminium hydroxide. 

The Use of Calcium Chloride. Calcium chloride should be in 
a granular porous form (size about 8-mesh) and free from dust 
particles, when used in the absorption train. The ordinary 
" anhydrous " material as obtained on the market can be 
made much more efficient by heating it to 26o~275 in a current 

1 Journ. Amer. Chcm. Soc. t 34 (1912), 911-2. 



240 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

of air dried over phosphorus pentoxide. 1 Even this porous 
material, however, which contains some surface moisture, is 
better than the fused calcium chloride. Calcium chloride gen- 
erally contains basic substances and these absorb carbon dioxide. 
On that account it must be saturated while in the absorption 
bottle with carbon dioxide by passing a stream of the dry gas 
through it for two hours and then displacing this with dry air 
or oxygen. Or, better, after driving out all the original air 
with dry carbon dioxide (one-half hour), let it stand overnight, 
and then displace the gas with dry air or oxygen. 2 

The amount of moisture absorbed by calcium chloride varies 
with the temperature even around the temperature of ordinary 
working conditions. 3 This is sometimes very important since 
the temperature of the calcium chloride in the drying train is 
seldom the same as that of the calcium chloride in the absorption 
train. 

To fill 4 the absorption bottle: Remove the stopper and its 
extension tube. Place a flat wad of cotton over the hole in 
the inside of the stopper 5 and rapidly fill the stopper and its 
extension tube with some of the alumina-pumice. Put in a plug 
of absorbent cotton near the end. Place this filled part of the 
bottle immediately into a desiccator over fresh cone, sulfuric acid. 
Without any delay, put some cotton at the bottom of the outer 

1 A. T. McPherson, " Granular Calcium Chloride as a Drying Agent," Journ. 
Amcr. Chcm. Soc., 39 (1917), 1317-9. 

2 Morse, " Exercises in Quantitative Chemistry " (1905), 340, 354, states that 
these methods are open to objections since the conversion into the carbonate is 
only superficial, and when the moisture comes in new surfaces are exposed. He 
also states that calcium chloride may be obtained in a neutral condition, that is, 
free from oxide, by evaporating a solution of the chloride with ammonium chloride 
and heating the residue until the latter salt has been expelled. 

3 Morse, ibid., 340-1. 

4 A long narrow pair of forceps with slightly curved ends, such as are used in 
biological work, and a pine splinter, will be found very convenient as aids in filling 
and also emptying the bottle. The pine splinter is used instead of a piece of metal 
since a scratch on the inside of the bottle will almost invariably cause a crack. 
Similarly a glass rod with a sharp end should not be used. If a wire is used, be 
sure that the end is protected with cotton. 

5 But do not fill the entire stopper with cotton, since the space is needed for the 
drying agent. 



ORGANIC COMBUSTIONS 241 

chamber of the main part of the bottle to keep particles from 
sifting through the holes and getting upon the ground surface. 
Insert a plug of cotton or a cork in the top of the inner standing 
tube in the center of the bottle, and then quickly fill the outer 
chamber with the alumina-asbestos mixture. Pack in some 
cotton above it near the top of the tube. This keeps the fine 
particles from getting upon the ground surfaces of the stopper 
and also from being blown out into the side arm. Take out the 
cotton or cork from the top of the inner standing tube, quickly 
remove all dust particles from the ground surfaces in the bottom 
of the bottle and at the top by means of cotton held in the 
forceps, carefully grease with a good stop-cock grease 1 and 
insert the stopper. Do not use vaseline, since it has no "body" 
and is too " thin," and causes sticking of the stopper. The 
ground surfaces, when properly greased, will appear clear, show- 
ing that the joints are gas tight. Great care should be used in 
greasing the lower ground joint. Too little grease will make it 
stick and too much may close the holes. If this ground joint 
becomes " frozen " there is little hope of being able to open the 
bottle. Keep the cotton from coming in contact with the 
ground surfaces. 

This bottle ought to be provided with a small ground stopper 2 
in one arm, and this arm is the one that is next to the combustion 
tube. Then when the combustion is over and the rubber stopper 
removed, the ground stopper is inserted and any water that may 
remain in the arm cannot evaporate during further manipula- 
tions. Only a very small amount of grease, if any, should be 
put on this stopper on account of the danger of rubbing it off 
and thus causing loss of weight. 

The side arms of the bottle are bent slightly upward near 



1 See footnote, p. 229. 

2 In case the absorption bottle is not provided with a small ground stopper, 
attach a short piece of rubber tubing and plug up the open end with a piece of 
glass rod. This serves to prevent the evaporation of any moisture that may 
remain in the arm. Since the rubber may vary in weight under the different 
conditions of treatment it should be removed and the arm carefully cleaned before 
the bottle is weighed 



242 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

the neck in order that any droplets of water that may collect will 
remain in the depression and not tend to run along the arm 
during subsequent handling. The side arms should be free from 
any dust particles which might be lost during the operation 
and change the weight. The cotton inside the bottle is used 
partly to prevent any particles from being carried by the gas 
into these side arms. 

Connect the arm prepared for the small stopper directly with 
the combustion tube by means of a good rubber stopper. 1 In 
doing this do not grasp the bottle itself take hold only of the 
side arm. Otherwise the arm may be broken off. Do not use 
any intermediate tube since water will collect in it and stay there. 
The ordinary rubber stopper is about 25 mm. long and tapers 
considerably. Since a snug fit is necessary and since precautions 
must be taken in order that the rubber stopper can easily and 
quickly be removed from the absorption bottle at the end of 
the combustion, cut off the ends of the stopper in such a way 
that it will be about 12-13 mm. long and that it will fit in the 
tube without leaving any spaces for the collection of water 
between the stopper and the tube. A longer stopper is very 
difficult to remove from the absorption bottle after the arm has 
been heated by the hot gases. Red rubber stoppers are the best. 
They should be thoroughly cleaned and all moisture removed. 
Sodium hydroxide will help to remove any sulfur. 

The gases can be passed through either the inner or outer 
chamber first by changing the position of the large stopper. 
Since some heat is evolved in the absorption of the water, it is 
better to pass the gas through the outer chamber first. In 
subsequent combustions the gas must be passed in the same 
manner, otherwise there is the possibility of the gas leaving the 
bottle with some moisture which it has taken up from the part 
already more or less saturated in a previous run. 

This absorption bottle and the one described next, when 
not in use, should be kept in a box packed with cotton for proper 
protection from breakage and dirt. 

1 Carefully breathe through the stopper for a moment and then it will slip over 
the tube more readily. Do not allow any excess of moisture to remain. 



ORGANIC COMBUSTIONS 243 

Before emptying the bottle, remove the grease from the 
ground surfaces with cotton. 

b. The Second Absorption Bottle. The carbon dioxide ab- 
sorption bottle is filled with moist soda lime in the outer chamber 
and with alumina-pumice in the inner chamber. The alumina 
must be used since the gas becomes moiast fter passing through 
the soda lime, and it must of course leave the bottle in as dry a 
condition as that in which it entered. The absorption bottle for 
this work is constructed with the idea of preventing the alumina 
from absorbing moisture from the soda lime when it is not in use. 
The only time that the two chambers are in communication is 
when the stopper is in " running " position. 

Place some cotton in the outer chamber at the bottom of the 
bottle around the holes at the base of the tube, insert a plug of 
cotton or a cork in the top of the inner standing tube, and fill 
the outer chamber with three layers of moist soda lime. 1 The 
bottom layer and the top layer should consist of soda lime with 
2 per cent of water and of 2o-mesh size, the middle layer of 
soda lime with 15 per cent of water and of i2-mesh size. Cover 
the top with cotton to keep it in place. Then quickly fill the 
inner stopper and its extension tube with the alumina-pumice, 
and properly protect it with cotton, as in the case of the first 
absorption bottle (p. 240, see footnote 5). Be sure that the 
flat wad of cotton covers the hole in the stopper and that most 
of the stopper is filled with the drying agent. This can con- 
veniently be done if it is filled while the stopper is inclined 

1 Soda lime is a mixture of sodium hydroxide and calcium hydroxide, and 
comes on the market in granular form of different sizes as anhydrous material 
and with different amounts of moisture. The anhydrous soda lime does not 
give rapid and complete absorption. (Compare Lamb, Wilson and Chancy, " Gas 
Masks Absorbents," Journ. Ind. and Eng. Chem., 11 (1919), 437~8.) A simple 
method of distinguishing between the anhydrous material and that containing 
moisture is to heat the sample in a test-tube and note whether moisture condenses 
on the upper walls. The absorption bottle described above will hold a total weight 
of about 20 grams of the moist soda lime. 

" Soda asbestos," a mixture of sodium hydroxide and asbestos in granular 
form, is recommended by G. L. Kelly, Journ. Ind. and Eng. Chem., 8 (1916), 
1038. See, also, Stetser and Norton, Iron Age, 102 (1918), 443~5J and Rogers, 
Canadian Chem. Journ., 3 (1919), 122. 



244 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

with the hole underneath. Rapidly clean the ground surfaces, 
and grease and put together as described above. See that the 
cotton does not get on the greased ground surfaces and also that 
the arms are free from particles. The glass stopper for one arm 
is, of course, not necessary in this bottle. 

Connect this absorption bottle with the first absorption 
bottle by means of 3.5 to 4 cm. of heavy- walled rubber pressure 
tubing. 1 Here also do not grasp the bottle itself, but take 
hold only of the arm (compare p. 242). In order to avoid loss 
of gas the arms of the two bottles should almost meet, but care is 
necessary to prevent the edge of one from rubbing against the 
other since the glass is easily chipped off when they are brought 
together inside the heavy tubing. Sometimes it is advisable 
to wire these joints with No. 16 copper wire. 

The gas must be passed into the outer chamber first. 

One charge of soda lime (about 20 grams) is good for two 
combustions. Sometimes it can be used for one or two more, 
but then there is always a risk that the absorption may not be 
complete. Soda lime, when moist, absorbs carbon dioxide very 
rapidly and gives off considerable heat. Sometimes the soda 
lime is of a light yellowish-brown color which is due to the 
presence of some compound of iron from the pots in which it is 
prepared. As the absorption progresses, the color changes to 
white and thus it gives a measure of how much soda lime is 
being used. It is noticed that the color changes evenly as the 
absorption takes place. The presence of iron also helps by 
accelerating the rate of absorption, according to Guareschi. 2 

On account of the heat generated during the absorption, 
droplets of water will sometimes collect on the walls in the 
upper part of the outer chamber. This, of course, will do no 
harm. 

In cases where many combustions are being run, and especially 
where extreme accuracy is required, it is desirable to add another 

1 Carefully breathe through the tubing. Compare note on the rubber stopper, 
p. 242. 

2 " Supp. ann. all'enciclopedia di chimica," Aug., 1915, Ckem. Abstracts, 10 



ORGANIC COMBUSTIONS 245 

absorption bottle filled like the one described above with both 
soda lime and alumina-asbestos. This is weighed also 'and its 
weight indicates when the first bottle will no longer absorb 
carbon dioxide completely. Or instead, the second bottle of 
the train may be filled only with soda lime and the third one 
only with the alumina-asbestos. When the blank run (p. 246) 
is made with this latter combination, the third bottle should gain 
as much as the second bottle loses. In both of these combina- 
tions the sum of the gains of each bottle at the end of a com- 
bustion represents the total increase in weight due to carbon 
dioxide. 

Note on emptying the bottle. The soda lime becomes hard 
and caked on standing after the absorption of carbon dioxide 
and care must be exercised in removing it. A pine splinter 1 
is useful in breaking up the mass. Often it becomes necessary 
to moisten the mass to soften it. Too much water must not 
be used and it must be poured off at once, otherwise the bottle 
may be cracked on account of the heat and expansion of the mass. 
Dilute hydrochloric acid will remove the particles adhering to the 
walls. The alumina-pumice must also be renewed. 

c. Guard Tube and Palladious Chloride Solution. To the car- 
bon dioxide absorption bottle attach an ordinary calcium chloride 
tube which has the small end bent at 90, and which has been 
half filled with the alumina-pumice mixture kept in place with 
plugs of cotton. At the wide end of the tube arrange a short 
glass tube, with a narrow opening, for leading the gas into a very 
dilute solution of palladious chloride. By leaving the drying 
tube half empty, we have a reservoir for any of the palladious 
chloride solution that might be drawn back, and thus it is pre- 
vented from entering the absorption bottle. 

The palladious chloride solution is used for detecting any 
carbon monoxide from an incomplete combustion and also for 
indicating the rate of absorption of the products of combustion 
by comparing the bubbling here with that in the bubble counter. 
This will be discussed later (see p. 255). The solution is of a 
light-yellow color, and is prepared by mixing i cc. of a 
1 See foot-note, p. 240. 



246 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

5 per cent solution of palladious chloride with 200 cc. of dis- 
tilled water. From this very dilute solution carbon monoxide 
precipitates metallic palladium, which appears as black colloidal 
particles. The solution should be protected from any carbon 
monoxide in the room, especially when the laboratory is sup- 
plied with water gas. When in use the bottle should have a 
stopper through which passes the glass tube and which has a 
channel cut in the side to allow the gases to escape. 

The short glass tube mentioned above leading into the pal- 
ladious chloride solution, should be drawn out into a narrow 
opening like the one in the bubble counter, in order that the 
comparison of the rate can be made. Since the viscosity of the 
sulphuric acid is different from that of the palladious chloride 
solution and since the gas pressures are also different in each 
case, the rate of bubble formation will not be exactly the same, 
but a good idea of the " normal " rates can be obtained by 
comparing the bubbling before the substance begins to burn. 

Instead of the small bottle for the palladious chloride solution 
a bubble counter can be used. In this case the drying tube pre- 
ceding it is placed in a horizontal position. It is difficult to 
clean the bubble counter. If metallic palladium is precipitated 
it can be dissolved in nitric acid. 

V. Method of Running Blank Determinations 

Since there is the possibility of many errors in the apparatus 
and chemicals; no combustion should be run until the operator 
is certain that everything is all right. The only satisfactory 
method of finding this out is to run a blank determination. 

After the apparatus is all set up (without the boat and the 
absorption train), heat the combustion tube to the same tem- 
perature that will be used later in the determination, that 
is, to a cherry red, and pass in purified oxygen gas at the proper 
rate during the course of about two hours. This procedure 
is sometimes called " glowing out." At first, moisture will 
condense near the open end of the tube. After this moisture 
has disappeared attach an ordinary calcium chloride drying tube 



ORGANIC COMBUSTIONS 247 

filled with granular anhydrous calcium chloride, which is properly 
protected at each end with plugs of cotton. Later a drying tube 
filled with the alumina-pumice can advantageously be used. 
The combustion tube should now be in good condition but the 
final proof is made as follows: 

Remove the drying tube from the end of the combustion 
tube, and, without changing the heating or the oxygen gas, 1 
attach the entire absorption train as if for a regular combustion. 
The bottles can be supported by means of copper wire hooks 
hung from a rod, or simply allowed to stand on a platform 
arranged at the proper height. They can be protected from the 
heat of the furnace by means of an asbestos shield. After 
thirty or forty minutes, disconnect the absorption train, replace 
the drying tube, and immediately weigh the absorption bottles. 
See p. 248 for weighing these bottles. Then re-attach the ab- 
sorption train and allow it to remain under the same conditions 
as before for another thirty or forty minutes. 2 Weigh again in 
the same order as before. If the difference in each case is not 
greater than 0.0002 to 0.0003 gram the entire apparatus may be 
considered as all ready for the combustion. If necessary try 
another blank run. If the first absorption bottle continues to 
gain, then the purifying train is probably not doing its work 
and the alumina should be renewed. If the second absorption 
bottle containing the soda lime loses weight then the alumina- 
pumice has become saturated with moisture and must be re- 
newed, or it is insufficient in amount. 

Be sure to attach the drying tube to the end of the com- 
bustion tube, every time the absorption train is removed. 

The error as shown by the blank determination should be a 
minimum, not more than the error in weighing. Other errors due 
to burning the sample, to improper weighing, etc., are likely to 
occur, but these can be more readily remedied provided the ap- 
paratus itself is all right. 

1 Do not allow the absorption bottles to remain long stoppered up after attach- 
ing since the pressure of the oxygen will become so great that the stoppers will 
be blown out. The stoppers can be put in " running " position just before attach- 
ment and then there will be no chance for trouble. 

2 During this time the substance can be weighed out. See p. 250. 



248 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

In a later chapter the relative weight of the small variations 
in the blank runs are discussed (p. 259). 

VI. Weighing the Absorption Bottles 

It has often been found that the greatest of all the errors 
lies in the weighing of the absorption bottles. The method 
given here is not claimed to be perfect but in our experience it 
gives excellent results. When it is considered how many changes 
the absorption bottle goes through, changes due to the passage of 
hot gases, handling in making the connections, deposits from the 
laboratory atmosphere of dirt and moisture, etc., it is no wonder 
that concordant results cannot be obtained unless great care and 
consistent treatment is given. 

In the first place, the absorption bottles should be weighed 
each time right after being removed from the combustion tube. 1 
Then general conditions will always be as nearly the same as 
practicable. The only alternative would be to let the bottles 
stand for many hours, but this of course cannot usually be done. 

The bottles must be scrupulously clean when being weighed, 
otherwise surface conditions would vary too much. Wipe them 
very carefully with a clean dry cloth which is free from sizing 
and starch. A towel or handkerchief which has been washed 
many times is suitable. Good quality lens cloth is excellent for 
this purpose. It should only be used a few times. Make sure 
that all excess of grease around the stopper is removed by the 
first wiping in order that later cleanings will not change the weight 
on this account. Wipe very thoroughly every part of the bottle. 2 
Be careful not to break off the side arms. It may be necessary 
to rub hard at first, but afterwards this should not be done since 
rubbing with a dry cloth induces a static charge of electricity 
and this apparently has much to do with discordant results 
when the apparatus is weighed under these conditions. 3 

1 Dudley and Pease, Journ. Amer. Chcm. Soc., 16 (1893), 541; Levene and 
Bieber, Journ. Amer. Chcm. Soc., 40 (1918), 462. 

2 A disadvantage of many kinds of absorption apparatus is that they cannot be 
cleaned properly. 

3 H. K. Miller, in an article on " Electrical Disturbance in Weighing" (Journ. 
r. Chcm. Soc., 20 (1898), 428), states that " Careful experiments led to the 



ORGANIC COMBUSTIONS 249 

A change of several milligrams is a common occurrence. In 
order to dissipate this static charge some analysts allow the 
absorption apparatus to remain for a definite time (four minutes, 
for example, on the balance pan after wiping before taking 
the final weight 1 ). However, there is a question whether 
the conditions are always the same since the wiping is not always 
the same. The bottle cannot be left too long before weighing, 
because as the charge is slowly being dissipated, and the apparent 
weight becoming less, it will begin to gain on account of the 
deposit of moisture, and no constant weight will be found. 2 

Another method to obtain a constant weight after the wiping 
is to pass the thumb and one finger down opposite sides of the 
bottle at the same time, and then immediately set the bottle on 
the balance pan and weigh. Repeat the alternate wiping and 
passage of the thumb and finger and weighing until the weight 
is constant or does not vary in two consecutive weighings by more 
than 0.0002 gram. This may require from four to ten complete 
repetitions. Perhaps the use of the fingers on the bottle just 
before weighing is open to question, but the method gives such 
good concordant results and is so rapid that we are willing to 
recommend it. The fingers should be clean, and are usually 

conclusion that in wiping the flask it became electrified, and that this static charge, 
acting on the floor of the balance, induced on it a charge of opposite character, 
and that the mutual attraction between these two charges of electricity had the 
effect of apparently increasing the weight of the flask. The potential of the 
charge would vary with the atmospheric conditions and with the manner of wiping 
the flask. By using a linen cloth in very dry weather, it was found possible 
to produce a charge on a 100 cc. flask which would require 0.08 gram additional 
weight to restore equilibrium. A high charge like this, however, would be rapidly 
dissipated and the flask would appear to lose weight. It was found that a charge 
which apparently caused an increase in weight of about o.oi gram would be re- 
tained quite a long time, and one might readily overlook the error which would 
thus be introduced. It was further found that a small charge would be retained 
many days on a flask kept in a desiccator. In damp weather a charge would 
readily pass off and not give rise to an error, but on a very dry day the practice of 
wiping glassware just before weighing is liable to cause serious errors." 

1 L. E. Wise, Journ. Amer. Chem. Soc., 39 (1917), 2062. Small apparatus in 
connection with micro-analysis was used in this work, and the error is not so large. 

2 See also article by Rae and Reilly, Chem. News, 114 (1916), 187-9, 200-3. 
Prof. T. W. Richards has recommended the use of uranium oxide or radium I ro- 
mide in the balance case to dissipate these charges. 



260 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

slightly moist while handling the cloth and the bottle, and the 
very small amount of moisture and grease from the skin that may 
be left upon the surface of the bottle is no doubt fairly constant 
and involves an error far less than that caused by the static 
charge. The bottle should not, of course, be touched by 
the fingers except as directed. 

Difficulty is sometimes experienced in obtaining concordant 
results on damp days, 1 but with proper precautions good results 
can be obtained without much trouble. 

Since the absorption bottles are often shut off and discon- 
nected under different pressures of oxygen, it is well to release 
the pressure within the bottle by momentarily opening the stop- 
cock, before weighing. 

A fine analytical balance must of course be used, and it 
should have a capacity of 100 grams for accurate work. The 
absorption bottles, when filled, seldom weigh much over 90 grams. 

For an excellent discussion of and careful directions for 
weighing, calibration of weights, etc., you are referred to an 
article by Rae and Reilly, in Chem. News, 114 (1916), 187-9, 
200-3, an d to t* 16 forthcoming book on quantitative analysis 
by Professors H. T. Beans and Harold A. Fales of the Depart- 
ment of Chemistry, Columbia University. 

A counterbalance weight or bottle is sometimes used by some 
analysts in weighing the absorption apparatus. A similar 
piece of apparatus is made to weigh approximately the same by 
adding lead shot, and is kept beside the absorption apparatus 
all the time and treated just the same in every way, as far 
as possible. 

VII. Weighing the Substance 

Since organic substances are generally hygroscopic and 
since it is necessary to keep all moisture away from the sub- 
stance up to the very time it is put into the combustion tube, 

1 Dudley and Pease, Journ. Amer. Chem. Soc. t 16(1893), 540, state, " If we may 
trust our experience it is almost impossible to make satisfactory combustions in 
showery weather." These authors just weighed the apparatus direct from the 
furnace, without wiping. Their combustion consisted of determining carbon in 
steel. 



ORGANIC COMBUSTIONS 



251 



the sample should be weighed in a closed tube and kept l there 
until transferred to the combustion tube. This is done in the 
boat tube illustrated in Fig. 18. On account of its shape it 
is known in laboratory parlance as the " piggie " in order to 
distinguish it from the other types of weighing tubes. The legs 






are placed in the center in order that the tube will rest securely 
on the balance pan. If they are near the stopper, as in some 
models, they are likely to slip off the edge of the ordinary balance 
pan and then the tube will roll and the boat will be upset. 

1 If the substance readily sublimes, it should be weighed out just before beginning 
the combustion and not kept in the boat tube for any length of time. 



252 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

The porcelain or quartz boat, 1 properly cleaned, heated in 
a non-luminous flame, and cooled in a desiccator, is placed in 
the " piggie " and both weighed together. Then the boat is 
removed with tongs or forceps, the substance added, and all 
weighed together again. The difference in weight is therefore 
the weight of sample used. Similar precautions should be taken 
here in cleaning the outside of the " piggie " and in handling it, 
as given for the absorption bottles, see p. 248. When not in use 
both the boat tube and the boat should be kept in the desiccator. 

For weighing out liquids, see p. 267. 

Ordinarily the amount of substance used for a combustion 
should be about 0.2 gram, with an allowance of about 0.02 gram 
above or below, since the actual weight need not 'be exactly 
0.2 gram. With too small an amount of substance the propor- 
tional errors are greater and with a larger amount too much 
time is consumed in running the combustion. The weight should 
be carefully taken to the fourth decimal place, and properly 
recorded. 

The substance should be perfectly dry. If necessary spread 
it upon a clean dry weighed watch glass, determine the total 
weight and set aside in a desiccator over fresh cone, sulfuric 
acid for at least twenty-four hours. Then weigh again. If the 
weight has changed put the substance back again for another 
period. The drying can be hastened by first placing it on the 
watch glass as above and setting it in an oven heated to 110 C. 
and after several hours allowing it to cool in a desiccator. This 
treatment cannot be given to all organic substances since many 
sublime, melt or decompose at that temperature. The latter 
can be dried in a vacuum oven at about 50, or in a vacuum 
apparatus 2 provided with a drying agent and kept at the tem- 
perature of boiling acetone (56). 

In case it should be necessary to determine the hydrogen 
in a substance containing moisture, whose moisture content is 

1 See p. 236. 

* Abderhalden's " Handbuch der Biochmischen Arbeitsmethoden," I (1910), 
296; also, in Eimer & Amend, N. Y., catalogue, under the name, " Vaccum 
Drying Apparatus, Abderhalden's." 



ORGANIC COMBUSTIONS 253 

known, the hydrogen cannot be directly calculated to the dry 
basis like the carbon since the hydrogen has been obtained 
from the total weight of water absorbed in the first bottle. 
Therefore, the amount of water in the sample must first be 
subtracted from the weight of water absorbed, and the hydrogen 
calculated in the remaining weight of water. The percentage 
can then be obtained using the weight of moisture-free sample. 

VIII. The Combustion Proper 

After it has been shown by the blank determination (p. 246) 
that the entire apparatus is all right, turn off the heat in the small 
section (No. i) of the furnace and allow this end of the tube 
near the purifying train to cool to room temperature. Raise the 
upper half to hasten the cooling, At the same time push back 
the two other heating sections in order that the space for the 
boat will become cool. 

When the forward end is cool, turn off the oxygen, shut off 
the stop-cock in the adjacent drying tube, disconnect the purify- 
ing train from the combustion tube and pull out the roll of 
oxidized copper gauze by means of the copper wire with hook 
already prepared for this purpose, making sure that the roll is 
placed upon some clean surface where it will not be in contact 
with any organic material. Then carefully remove the boat 
containing the weighed amount of substance from the boat -tube 
(" piggie ") by means of forceps, put it into the tube, and 
shove it back with the copper wire into its proper position about 
2.5 cm. from the cerium dioxide. Replace the roll of oxidized 
gauze, connect the purifying train, and let the oxygen pass 
through. 

Remove the guard tube from the other end of the combustion 
tube and attach the entire absorption train (p. 247, including foot- 
note). If the substance is readily distilled out of the boat the 
absorption train should be attached before the boat is put into the 
tube. As a rule this is not necessary, and it is easier to attach 
the absorption train afterwards. 

Regulate the passage of the oxygen in such a manner that the 



254 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

bubbles passing through the sulfuric acid in the bubble-counter 
can just be counted that is, at the rate of about three to four 
a second. 

It is very difficult to describe in detail the actual method 
of burning an organic substance, since each substance has its 
own peculiarities and therefore only a general description can be 
given. An idea as to how the substance behaves on heating 
should be gained beforehand, if sufficient is available, by gently 
heating it and gradually burning it in a boat over a small flame. 1 
Gradually move the large heating section (No. 2) a centimeter 
at a time, toward the boat, until most of the cerium dioxide- 
pumice is heated to redness. At the same time, provided the 
substance is not too volatile, turn on the switch and allow the 
small heating section (No. i) to become warm and finally hot, 
but not to red heat, except in special cases. Also heat up the 
last section (No. 3) so that no water will condense in that end of 
the combustion tube. These operations ordinarily require about 
ten minutes. Then move the large heating section (No. 2) 
closer to the boat until the cerium dioxide-pumice is all being 
heated, and the asbestos plate on the end of the heating section 
is over the asbestos plug between the cerium dioxide-pumice and 
the boat. Now very slowly, just a little (0.5 cm.) at a time, move 
the small heating section (No. i) toward and finally over the boat. 
With substances that sublime readily, it may only be necessary 
to bring the small heating section (No. i) to a moderate tem- 
perature to drive all of the sample over the cerium dioxide- 
pumice. With an active catalyst the forward points of the im- 
pregnated pumice will glow. 2 The glow cannot always be seen 
on account of the asbestos. With some substances the forward 
part of the pumice mixture will appear gray as the decomposition 
begins. This is probably due to particles of carbon which 
are 'later burned completely. The burning of the substance 
ordinarily requires from ten to twenty-five minutes, depending 
upon how rapidly the substance can be distilled and burned. It 

1 Weyl, "Die Methoden der organischen Chemie," I (1909), 17; and Wise, 
Journ. Amer. Chem. Soc., 39 (1917), 20. 

2 In some cases the little roll of copper oxide gauze in front of the asbestos 
appears to act catalytically since it also glows under certain conditions. 



ORGANIC COMBUSTIONS 255 

is well to take the longer time specified for burning the substance 
the first time in order to learn any of its peculiarities. 

During the course of the combustion the operator must be on 
the alert and watch not only the burning of the substance but 
also the temperature (compare p. 231) which will gradually rise, 
and the rate of flow of the oxygen gas coming in and of the gases 
leaving the apparatus through the palladious chloride solution. 
Bubbles of gas should always be coming through the palladious 
chloride solution. If their number is diminishing so rapidly 
that it appears they may stop then more oxygen should immedi- 
ately be turned on in order that there may be an adequate supply 
for complete combustion. The presence of a black precipitate 
(colloidal palladium) in the palladious chloride solution indicates 
that carbon monoxide has been coming through the absorption 
train, and therefore that the combustion is incomplete and the 
determination no good (p. 245). 

Soon after the combustion begins, moisture will condense in 
the forward arm of the alumina bottle, and then the soda lime 
bottle will become warm. The general operation should be con- 
tinued until this latter absorption bottle is practically the 
same as the first one in temperature, as shown by the hand. 
The absorption bottles can be protected from the heat of the 
furnace which is not very great, by means of an asbestos shield. 

After all the particles of carbon have disappeared from the 
boat the passage of the oxygen should be continued for at least 
forty-five minutes in order that all the products of combustion 
will be swept out and properly absorbed. During this time the 
temperature may gradually be reduced. Little care is needed 
after all the substance has disappeared and the boat is clean, 
except to see that the gas is passing all right and the tempera- 
ture does not go so high that the tube is melted. Sometimes 
particles of black cupric oxide are found in the boat, having 
been swept along from the roll of oxidized gauze by the oxygen. 1 

1 Levene and Bieber, Journ. Amer. Chem. Soc., 40 (1918), 461, recommend that 
a small coil of fine platinum gauze be placed between the roll of oxidized copper 
gauze and the boat to prevent the particles of cupric oxide from getting into the 
boat. This is very important when the ash of the substance is to be weighed or 
analyzed. 



256 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

This of course gives the appearance of unburned carbon and its 
presence is annoying since the end of the combustion is indicated 
by the absence of black carbon particles. That the particles 
do consist of cupric oxide can sometimes be established by the 
fact that they do not disappear after prolonged heating. Later, 
when the boat has been removed, the proof can be made definite 
by seeing if they are soluble in nitric acid. It should be noted 
however, that carbon particles formed under certain conditions 
are very difficult to burn (so-called " graphitic " carbon). 

If moisture collects in the combustion tube just in front of 
the absorption apparatus and persists even for some time after 
the substance has been burned, it should be driven through by 
slowly drawing the tube further into the furnace. Consider- 
able care is necessary for this gradual heating to prevent the burn- 
ing of the rubber stopper and also the cracking of the tube. 1 

After the tube has been " swept out " for the forty-five 
minutes from the disappearance of the last particles of carbon 
in or around the boat, the absorption bottles are closed, dis- 
connected and immediately weighed (p. 250). The guard tube 
should be replaced and the combustion apparatus is then ready for 
another determination without further treatment. 

The time from putting the boat into the tube until the 
absorption bottles are taken to the balance usually is from an 
hour and ten minutes to an hour and a half. A little experi- 
ence soon makes it possible to cut this down to an hour, or to 
forty-five minutes, provided no special difficulty is encountered 
in burning the substance. 

Two combustions should always be run on the same substance 
whenever possible, and they should check up within narrow 
limits. See discussion of results, p. 258. 

NOTE 

If no cerium dioxide is used the layer of cupric oxide wire must 
be much longer, 40-70 cm., and the substance must be burned very 

1 If a gas furnace is employed, the water may be driven over by holding one of the 
hot tiles under the tube. Some operators use a small flame, but great care is 
necessary to prevent cracking the tube and burning the stopper. 



ORGAXIC COMBUSTIONS 257 

slowly. At least forty minutes is required just for the burning alone, 
and some substances are not completely oxidized even when the time 
is considerably extended. 

IX. Calculations, and Discussion of Results 

Since the ratio of H 2 to H 2 O is : * which is equal to 

18.016 n 

0.1119, the weight of hydrogen in the weight of water found can 
be calculated by multiplying the weight of water by 0.1119. 
The percentage of hydrogen is equal to the weight of hydrogen 
multiplied by 100 and divided by the weight of the substance 
used. Or the following formula may be used: 

Per cent H _Weight H 2 OX 2. 016X100 ^ 
Weight substance Xi8.oi6' 

For logarithmic calculation: 



Add 



Log. wt. H 2 O = 
Log. 100 = 

Log. 0.1119 =9.048710 



Subtract Log. wt. subs. = 
Log. per cent H = 

Similarly, since the ratio of C to C0 2 is if or A, which is 
equal to 0.2727, the weight of carbon in the weight of carbon 
dioxide found can be calculated by multiplying the weight of the 
carbon dioxide by fr or 0.2727. The percentage of carbon 
is equal to the weight of the carbon multiplied by 100 and divided 
by the weight of the substance used. Or, 

Per cent c ^ Weight CO 2 X 3 Xioo 
Weight substance X 1 1 " 

1 Using H = i.oo8. 



258 LABORATORY MANUAL OF ORGANIC CHEMISTRY 
For logarithmic calculation: 



Add 



Log. wt. CO 2 



Log. 100 = 

Log. 0.2727 =94357 ""10 

Subtract Log. wt. subs. = 

Log. per cent C = 

For ease in calculation, a table of four-place logarithms is 
given on pages 308-11. 

The figures showing the percentage of carbon and hydrogen 
should not be extended beyond the second decimal place. The 
figures beyond the second decimal place in this work are not 
significant. 

Limit of Error. In order to be able to compare the results 
of analyses to see whether they are what they should be, some 
standard is necessary for the limit of error. The criterion for 
the limit of error in good analytical work is one part in one 
thousand. Many examples can be given to show that the deter- 
mination of carbon approaches this limit, although the hydrogen 
is not so good. The number of parts per thousand error, X, 
can be calculated by using the following ratio: Difference of 
percentages : percentage :: X : 1000; or 

^_Diff. of per cents Xiooo. 
per cent ' 

where one percentage, often the theoretical, is taken for the basis 
of comparison. This is made more clear by means of the exam- 
ples which follow: 

A sample of cane sugar (Ci2H220n) was analyzed with the 
following results: = 42.05%; H = 6.48%. 1 The theoretical 
percentages for this substance are 0=42.09%; H = 6.46%. The 

! This analysis was made by Mr. R. T. Feliciano. His check analysis was 
C = 42.i4% and 42.15%; H=6.46% and 7.00%. Similar results were obtained on 
the same substance by Mr. H. R. Pyne: C = 42.iQ% and 42.07%; H = 6.23% 
and 6.26%. Alumina-asbestos mixture was used in the first instance, and 
alumina-pumice in the second. 



ORGANIC COMBUSTIONS 259 

difference between the theoretical value for C and the value 
actually obtained is 0.04. Therefore the error, expressed as parts 

per thousand, is -^ which equals 0.95 (approximately 

42.09 

one part per thousand). Correspondingly, for H, the differ- 
ence between the theoretical value and the value actually found 

, 0.02X1000 - , ,, , r . . 

is 0.02; and - - =3.1 parts per thousand. This is an 

0.40 

excellent analysis. The same comparison can of course be made, 
and should be made, between any two percentages found. 

An example with a very high percentage of carbon: Analysis 
of anthracene (CuHio): Found, = 94.17%; H = 5.7i%; 1 
the theory being = 94.34%; H = 5.66%. The error for C is 
( 94 .34-94.i7)Xiooo = ^ g thousand; for H? the error is 

94-34 

(5.7i-"5.66)Xiooo ==88 ^ thousancL 
5.66 

The " allowed " error for carbon ought not to be more than 
2.5 parts per thousand, and never over 5 parts per thousand. 
For hydrogen, the " allowed " error ought not to be more than 
20 parts per thousand, and never over 30 parts per thousand. 

Now it is possible to tell the extent of the errors which are 
found in connection with the blank runs (p. 247). If an increase 
of o.ooio gram is noted in the case of the first absorption bottle, 
this means that in a regular combustion, which would ordinarily 
require about twice the time of the blank run, the increase 
would probably be about 0.0020 gram. On the basis of using 
a 0.2 gram sample, this gain, counted as water, would be equal 
to o.i i% H ; and if the substance contained 5.0% H, the error due 
to this cause alone would be 22 parts per thousand, which is 

1 This analysis was made by Mr. Henry L. Faust and is the first one which 
showed us that alumina could be used in organic combustions. The same substance 
was later analyzed by Mr. David I. Hitchcock with the following results: 
= 94.36% per cent and 94.12%; H = 5.57% and 5.53%. 

For the sake of comparison, the very first results obtained by using the alumina- 
pumice mixture are added: Salicylic acid; found, C = 60.77% and 60.82%; 
H = 4.47% and 4.38%; theory, = 60.84%; H=4.38%. This work was done 
by Mr. Geo. H. Walden. 



260 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

about the " allowed " error. Correspondingly, if the same gain 
of o.ooio gram is noted in the case of the second absorption 
bottle, meaning about 0.0020 gram for a combustion, on the 
basis again of a 0.2 gram sample, this would be equivalent to 
0.27% C, and supposing the C = 6o%, the error on this account 
alone would be 4.5 parts per thousand, which isJbeyond the 
ordinary " allowed " limit of error. Any other error in the 
work would in each case put the determination way beyond 
what it should be. 

The limit of error of 0.0002 gram in weighing alone would, 
under the conditions mentioned above, be equal to 4.4 parts per 
thousand for the hydrogen and 0.9 parts per thousand for the 
carbon. 

These figures are given in order to show that the greatest 
care at all times must be exercised in carrying out the work. 

Two combustions should always be run whenever possible, 
and they should check up within the limit of error specified above. 

NOTES 

1. For calculating the hydrogen in a sample which contains some 
moisture and whose moisture content is known, see p. 252. 

2. The percentage of C and H in a hydrocarbon should add up to 
ioodbo.3 per cent. 

3. The percentage of oxygen in a compound is found by differ- 
ence. This method of calculating throws all the error upon the 
figure for this element. (For a method of determining oxygen 
directly, see Boswell, Journ. Amer. Chem. Soc., 36 (1913), 284-90; 

36 (1914), 127-32.) 

4. The empirical formula of a compound is found by dividing 
the percentage of each element by the atomic weight of the element, 
and the ratio is then expressed in whole numbers by dividing each 
term by the lowest value or by some simple fraction of this value. 
Since these numbers as found by analysis seldom are whole numbers, 
the formula which has been found in this way should always be 
checked up by calculating the percentage composition of each 
element from the formula so obtained and comparing the values with 
those found experimentally. They should agree within the limit 
of error set forth above. 



ORGANIC COMBUSTIONS 261 

The molecular formula can only be obtained after a molecular 
weight determination has been made. 

Sometimes the empirical formula cannot be selected since the 
results are too close to several possibilities. In this case some 
derivative of the substance should be made and then an analysis 
carried out on this new product. Usually the figures so obtained 
will settle the question. (An interesting case is the determination 
of the formula of cholesterol, see Glikin, " Chemie der Fette, Lipoide 
und Wachsarten," I (1912), 334-5, where Reinitzer's work is quoted 
from Monatshefte, 9 (1888), 421.) 

X, Some Common Errors and How to Avoid Them ' 

Many of the errors have already been discussed in connection 
with different parts of the apparatus, the method of running 
the combustion, etc., and many errors are perfectly obvious. 
Yet it has been our experience that direct attention must often 
be drawn to some errors before they arc corrected, and it is 
the most obvious error which is sometimes committed. There- 
fore all that have been noticed in actual work are mentioned. 

Read over once again Liebig's advice which is quoted at the 
end of the historical introduction (p. 223). 

The Apparatus 

1. Do not use too much sulfuric acid in the bubble counter. 

It may suck back or be splashed over and cause trouble 
with the rubber tubing and stopper (p. 227). 

2. The pre-heater should not be heated to such an extent that 

the glass tube melts. Watch the temperature (p. 231). 

3. Use heavy- walled " pressure " rubber tubing. Other kinds 

are not gas tight and do not fit snugly. Wire joints, if 
necessary, with No. 16 copper wire, and use a pair of 
pliers to tighten them (p. 244). 

4. See that the glass stoppers are properly greased (p. 229). 

Attach a piece of twine to prevent them from being blown 
out in case of excess of pressure (p. 229, (footnote)). 

5. Use red rubber stoppers, and clean them well, inside as well 

as out (p. 242). 



262 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

6. Cut the rubber stopper properly for connecting the first 

absorption bottle to the combustion tube (p. 242). 

7. Do not use a piece of glass or rubber tubing to connect the 

first absorption bottle with the combustion tube (p. 242). 

8. Do not fill the stoppers of the absorption bottles with cotton. 

The space is needed for the drying agent, especially in 
the soda lime bottle (p. 243). 

9. Do not allow the two absorption bottles to come so close 

that the ends of the arms are chipped (p. 244). 
10. See that there is space provided above the palladious chloride 
solution for any emergency in case of back pressure (p. 245.) 

The Chemicals 

1. Purify ail oxygen by passing it through the pre-heater 

(p. 228). 

2. Use the specified soda lime for both drying and absorption 

trains (pp. 229, 243). See that it is of proper size and 
moisture content. 

3. Use the same drying agent in the drying train that is used 

in the absorption train (p. 230). 

4. Do not expect the materials in the drying train to last for- 

ever. 

5. Keep the stop-cocks of the U- tubes in the drying train 

closed when not in use (p. 229). 

6. See that the copper spirals are properly made and fit all right 

(P- 235)- 

7. Do not use cupric oxide wire for carbon and hydrogen that 

has been used for determining nitrogen, unless it has been 
re-treated (p. 236). 

8. Do not use alumina that has been heated too long or too 

high (p. 238). 

9. Keep the palladious chloride solution stoppered except 

when in use (p. 246). 

Weighing 

T . Use a proper analytical balance and, if you use a rider, see 
that it is the right one for your balance. 



ORGANIC COMBUSTIONS 263 

2. The absorption bottles should not have anything on them 

when weighed. Detach rubber stopper and tubing. 

3. Wipe each absorption bottle carefully and do not record the 

weight until you are satisfied that it is all right and that 
you can duplicate it (p. 249). 

4. Weigh the bottles in the same order each time and try to 

take approximately the same time in weighing. A 
slightly different weight is found when the bottle has been 
standing and is cold. 

5. Wipe off all grease from around the stopper of the bottle 

before you begin to weigh. After that be careful not to 
wipe off any more in all other weighings (p. 248). 

6. Make proper record of all weighings in a neat manner so 

that all figures are known. Do not leave anything to 
guess work. Do not throw away any papers until the 
work is completed and accepted. 

Blank Runs 

1. Continued findings of gain in weight of first absorption bottle 

shows that drying train needs attention, or that rubber 
stoppers are burning. 

2. Loss in weight of first absorption bottle usually means that (i) 

grease has been wiped off the stopper, (2) particles of the 
drying agent have been blown out of the bottle, or (3) the 
drying agent is " spent " and moisture is being removed 
from it by the dry gas from the drying train. 

3. Loss in weight of either bottle may be due to chipping the 

glass at the end of the arms (p. 244). 

4. Loss in weight of the soda lime bottle is usually due to 

" spent " drying agent, or not enough of the good material. 
Fill up the stopper (p. 243). Sometimes it is necessary to 
add a third bottle (p. 244). 

5. Loss in weight may be due to the fact that the gas is being 

passed through the bottle in the wrong direction, (p. 242). 

6. Loss in weight may be due to loss of particles from side arms. 

See that these are scrupulously clean (p. 242). 

7. Gain in soda lime bottle is generally due to the burning of 



264 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

rubber stoppers in the pre-heater or forward end of the 
combustion tube. If the rubber stopper next to the dry- 
ing train in the pre-heater tube is burned, some of the gases 
may go through the drying train incompletely absorbed, 
and then they will be burned in the combustion tube. 
The rubber stopper should not become spongy. 

The Combustion 

Some of the troubles mentioned under the previous heading 
apply here also. 

1. Do not fail to prove your apparatus by running a blank 

determination. 

2. Keep enough oxygen in the apparatus to supply the needs 

all the time. See that it is always bubbling through the 
palladious chloride solution (p. 255). 

3. Do not try to burn the substance too fast before you are fully 

acquainted with the apparatus. 

4. Remember that the combustion needs attention all the time. 

Do not try to do too many other things at the same time. 
Too much effort will be lost. 

5. Black particles in the boat near end of the combustion may be 

carbon or cupric oxide (p. 255). 

6. Do not let the small section become too hot, especially at 

the beginning (p. 254). 

7. If you weigh the absorption bottle with the little stopper 

for one arm, do not fail to keep it safe and weigh it again 
with the bottle later. 

8. It is most desirable as a rule to run a blank determination 

between two consecutive combustions, since all the moisture 
and carbon dioxide may not have been removed, especially 
if the time after the substance has been burned is cut 
short. 

9. If the percentage of hydrogen in a determination is high and 

the carbon low, this may be due to the fact that the gases 
have not been completely driven through the first bottle. 
Attach the absorption train to the drying train, pass the 
oxygen through for twenty minutes and weigh again. 



ORGANIC COMBUSTIONS 265 

XI. Combustion of Substances Containing Nitrogen, Sulfur, 
Halogens, Phosphorus, Sodium, etc. 

Nitrogen. With an active catalyst and plenty of oxygen, 
the nitrogen is oxidized to nitrogen dioxide. This is true even 
with substances containing nitrogen in the so-called " unoxi- 
dized " form, as in amines, amides, etc. Nitrogen dioxide is 
absorbed more or less by the drying agent and completely 
absorbed by soda lime. Therefore it is necessary to keep it 
from going into the absorption train. Lead peroxide (PbCb) 1 , 
kept at 3oo-32o, is the best means of " fixing " the nitrogen 
dioxide and preventing it from leaving the combustion tube. 
The temperature must be tried out ahead of time to find out 
the working conditions. Too high a temperature (above 
350) will cause the decomposition of the lead nitrate which is 
formed, and also will convert the PbO2 into Pb C>4. Since 
water vapor acts upon lead nitrate giving a basic nitrate and 
liberating nitric acid which is not all reabsorbed by the lead 
peroxide, it is necessary to mix an equal amount of PbsCU 
(minium) with the lead peroxide. Some PbaQi for use can 
readily be obtained by heating some of the lead peroxide in a 
tube or open disE to 4oo-45o. 

The lead peroxide mixture (7-8 grams) is placed in a tube of 
hard glass, Fig. 19, which fits the combustion tube snugly, and 
put in position F as shown on the general diagram, p. 233 (see 
also p. 236). Or it is placed in a large boat, 14 cm. long, pref- 
erably with the end open (broken olf) toward the catalyst. 2 

Lead peroxide is very hygroscopic and care must be used in 
handling it~and proving it in the blank run. It must be very 
pure, free from any organic particles such as dust, fibers from 

1 Lead peroxide was used by Liebig and contemporary workers in organic 
combustions to absorb acidic gases, and in 1876 by Kopfer, when he introduced the 
catalytic method (p. 219), but Dennstedt has done the best work on how to use 
it. See his " Anleitung zur vereinfachten Elementaranalyse," 3 Auft. (1910), 
66-70, 90. 

*Levene and Bieber, Journ. Amer. Chem. Soc., 40 (1918), 460, recommend 
putting the lead peroxide directly into the tube with alternate layers of a mixture 
of it with asbestos. 



266 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

filter paper, etc. It must also be free from lead oxide since 
this absorbs carbon dioxide at a high temperature. 1 

The combustion must be run slower than when the substance 
contains no nitrogen. 2 

Cupric oxide also absorbs nitrogen dioxide. The copper 
nitrate formed is only slowly decomposed around 300, and if the 
latter part of the cupric oxide just preceding the lead peroxide 
mixture is not well heated between combustions, the nitrate 
may accumulate to such an extent that it will entirely block 
the combustion tube. 3 




TUBE: FOR LEAD PEROX/DEM/XTURE 

FIG. 19. 

NOTES 

1. For the electrolytic preparation of the lead peroxide you are 
referred to Dennstedt's book mentioned above, p. 265 ; and to King- 
scott and Knight, " Methods of Quantitative Organic Analysis " 
(1914), 35. 

2. For other methods of combusting organic substances contain- 
ing nitrogen, see Gattermann, " Practical Methods of Organic 
Chemistry," 3d Amer. Ed., (1914), and especially, F. G. Benedict, 
" Elementary Organic Analysis " (1900), 59-64. 

3. For estimating carbon, hydrogen, and nitrogen simultaneously, 
see Dennstedt and Hassler, Ber., 41 (1908), 2778. 

Sulfur. For determining carbon and hydrogen by the cataly- 
tic method when the substance contains sulfur, the same pro- 
cedure is used as above when nitrogen is present. The sulfur 
is fixed as lead sulfate. 

1 Lassar-Cohn, " Arbcitsmethoden," Allgemeine Theil, 4 Aufl. (1906), 286. 

2 Reimer, " On Rapid Organic Combustions," Journ. Amer. Chem. Soc. t 37 
(1015), 1636-8. 

3 Fisher and Wright, Journ. Amer. Chem. Soc., 40 (1918), 868. 



ORGANIC COMBUSTIONS 267 

Other methods, when a catalyst is not used, are discussed 
in the books mentioned in the foreword. 

Halogens. The lead peroxide mixture also serves for fixing 
chlorine and bromine, but not iodine. A roll of silver gauze 
or a long boat containing so-called " molecular silver," prepared 
by treating silver halide residues with granular zinc, is used for 
all the halogens. 

Phosphorus, Sodium, Mercury, etc. Only notes and refer- 
ences will be given for these. 

Phosphorus is often converted into phosphoric acid which, 
on account of its physical state, holds back particles of carbon. 
It is then necessary to use an alundum boat, which is removed 
after most of the carbon has been burned, dialyzed to get rid of 
the phosphoric acid, dried, and put back with the carbon in it 
for complete conbustion. 

Sodium and other basic elements retain carbon in the ash 
as carbonate. F. G. Benedict, " Elementary Organic Analysis" 
(1900), 70, recommends the admixture of lead chromate and 
potassium dichromate with the substance to expel the carbon 
dioxide. Or the ash can be analyzed by the ordinary methods. 
See also Kuzirian, " The estimation of CO 2 in the ash of plant 
and animal substances," Journ. Ind. and Eng. Cfiem., 8 (1916), 
89, who uses sodium paratungstate. 

Mercury. " The simultaneous determination of carbon, 
hydrogen, and mercury," V. Grignard and A. Abelman, Bull, 
soc. chim., 19 (1916), 25-7. 

XII. Combustion of Liquids, Gases, and Explosive Substances 

Liquids. If the liquid substance has a boiling-point above 
about 170, it may generally be weighed directly in the boat 
as if it were a solid. There should be no delay, of course, after 
weighing the boat should be put directly into the combustion 
tube. 

Lower boiling liquids are weighed in a sealed bulb with a 
capillary tube. 1 This tube is then carefully broken off at a 

1 Liebig, " Instructions for the Chemical Analysis of Organic Bodies." Trans 
by Gregory (1839), 20. 



268 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

file mark, and the bulb and the piece are put into the boat 
in such a way that the tube will rest on the end of the boat 
near the cerium dioxide, and immediately placed in the 
combustion tube. It is slowly distilled out and burned in the 
usual manner. Part cles of glass in the bulb aid in the dis- 
tillation (suggested by M . E. M. Slocum). The substance 
should not, of course, be allowed to be carbonized within the 
bulb. 

A smal thin-walled glass bulb, 1 3-5 mm. in diameter, such 
as is often employed for molecular weight determinations 
by the vapor density method, is used. It is filled by placing 
it with the open capillary tube dipping into the liquid to be 
analyzed, contained in a dish, inside a vacuum desiccator. The 
suction is then turned on and after a few minutes air is allowed 
to re-enter the desiccator. This causes the liquid to be drawn 
into the bulb. The bulb should be weighed before, and again 
after sealing. 

Very low-boiling liquids must be driven into the combustion 
tube somewhat as in the case when a gas is analyzed. They 
often form explosive mixtures. 

REFERENCES 

Benedict, loc. cit., 73-9; Clarke, "Note on the combustion of 
volatile organic liquids." Jour. Amer. Chem. Soc., 34 (1912), 746-7. 

Gases. Since gases form explosive mixtures with oxygen, 
the oxygen must always be in very great excess when the gas is 
slowly being driven into the combustion tube. The gas is held 
in a gas burette in which it is measured, and slowly sent through 
a capillary tube into the combustion tube. A long cupric oxide 
spiral near the entrance helps to cause thorough mixing and to 
prevent " back firing." 

1 This small bulb can be made as follows: Heat and draw out a piece of ordinary 
gla s tubing, and cut off one end of the narrow tube at the shoulder. Then soften 
in the flame the end which has been cut off, and, with the other end as a mouth- 
piece, blow a bulb. It is completed by cutting the narrow tube at the desired 
length. 



ORGANIC COMBUSTIONS 269 

Explosive Substances. These are weighed out as usual in a 
boat and then mixed with three or four volumes of cupric oxide 
(which is free from moisture, etc.) or quartz sand. 



DIVISION B 

THE DETERMINATION OF NITROGEN 

I. Historical Introduction 1 

Gay-Lussac and Thenard (1810) were the first to determine 
nitrogen in organic substances. Their method consisted in burn- 
ing the substance in the presence of potassium chlorate and 
analyzing the gases evolved (compare carbon and hydrogen, 
p. 218). Later (1815) cupric oxide was introduced by them 
and is still used up to the present time. Liebig used this 
same method, improving it so that he could collect and weigh 
the water and carbon dioxide, and measure the nitrogen as a 
gas. Dumas 2 burned the substance in an atmosphere of carbon 
dioxide, prepared from lead carbonate in the end of the closed 
tube, and collected the nitrogen in a eudiometer over mercury 
and a solution of potassium hydroxide to absorb the carbon 
dioxide. He also used reduced copper to reduce any oxides of 
nitrogen which may be formed. Thus he laid the complete 
foundation of the method which is the most general and, when 
properly carried out, as accurate for nitrogen as any yet devised. 

Erdmann and Marchand 3 used an outside generator for the 
carbon dioxide, and Hugo Schiff 4 devised the azotometer 
which has been such a great help in handling the gases. It is 
of considerable interest to note how the azotometer was developed 
and modified. The references for the different forms (and each 
reference contains a sketch of the apparatus for which the 
author is sponsor), are found in Dennstedt's history, p. 40, and 

1 Dennstedt, " Die Entwickclung der organischen Elementaranalyse," Ahren's 
"Sammlung chemischer und chcmisch-technischer Vortrage," IV (1899), 29. 

2 Ann. Chim. pkys.,2 (1831), 198; Dennstedt 's history, p. 35. 
3/. p r . Ckem., 14 (1838), 213. 

4 Zeitschr. anal. Chem., 7 (1868), 430. 



270 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

Richter's " Organische Chemie," n Aufl., I (1909), 7. Mag- 
nesite (magnesium carbonate) later displaced the lead and other 
carbonates and is most generally used when the substance is 
burned in a closed tube. 1 

Many organic substances when heated, expecially in the pres- 
ence of soda lime, give up their nitrogen as ammonia, or some 
simple amine. This method was used for the determination of 
nitrogen by Varrentrapp and Will 2 in 1841. The ammonia 
formed is absorbed in a known amount of standard acid and the 
excess of acid titrated back with alkali. From this, the amount 
of acid neutralized by the ammonia is obtained and the ammonia 
and nitrogen can then be calculated. This method is not 
applicable to substances in which the nitrogen is in such com- 
bination as in the nitro-group, azo-group, etc. 

Some forty years later, in 1883, Kjeldahl 3 brought forth an- 
other method which on account of its ease of manipulation and 
applicability to many substances which are analyzed for nitrogen 
in great numbers, has been of inestimable service. The Kjeldahl 
method consists of heating the substance with cone, sulfuric 
acid usually in the presence of a catalyst, such as a mercury salt, 
potassium permanganate or cupric sulfate. This procedure 
converts the nitrogen into ammonium sulfate. The mixture is 
then diluted, made strongly alkaline with sodium hydroxide, 
and distilled. The solution of ammonia which constitutes the 
distillate is collected in a definite amount of standard acid and 
the analysis completed by back titration, etc., as outlined in 
the previous paragraph. Some substances, especially those with 
the nitrogen in the ring are not completely decomposed by the 
method. Otherwise, by different modifications for increasing 
the temperature by adding potassium hydrogen sulfate, by 
reducing nitro-compounds just previously, etc., the method 
has found wide application. 

Within very recent years micro-methods for determining 

1 This is the method outlined in Gattermann, " Practical Methods of Organic 
Chemistry," 3d Amer. Ed. (1914), 90. 

2 Ann. Chem. Pharm., 39 (1841), 257. 
*Zcitschr. anal. Chcm. 22 (1883), 366. 



ORGANIC COMBUSTIONS 271 

nitrogen by both the Dumas and Kjeldahl methods have been 
devised by Pregl. 1 

Since the Dumas or absolute method is so generally appli- 
cable even though it is slow and must be carefully watched, 
it is the one selected and described in the following pages. The 
chief difficulties are in obtaining pure carbon dioxide and in 
preparing the cupric oxide so that it will not continue to give 
off occluded gases. These points are fully discussed later and 
need not be repeated here. The modifications used bring the 
results within a fair limit of error (compare p. 302). One 
must work with gases and with pressures above and below 
atmospheric. On this account many stop-cocks are necessary 
to make the apparatus efficient. However, although the array 
of stop-cocks may appear formidable at first you will rapidly 
become familiar with their uses and then good results will soon 
follow. 

II. List of Apparatus and Chemicals for the Determination of 

Nitrogen 

Apparatus 

1. * Electric combustion furnace (p. 283). 

2. * Pyrex combustion tube, 76 cm. long and 15 mm. inside 

diameter, for 72 cm. combustion furnace (p. 283). 

3. * Asbestos paper for lining trough of the furnace (p. 231.) 

4. * Copper gauze, 40 mesh, i square foot (pp. 283-4). 

5. * Copper wire, No. 16, 3 feet long. 

6. Two red rubber stoppers, one-holed, size i or o depending 

upon the diameter of the combustion tube; one rubber 
stopper, one-holed, for the dropping-funnel; one rubber 
stopper, three-holed, for the generator flask; one rubber 
stopper, two-holed, for the safety bottle connected with 
the generator; and one rubber stopper, three-holed, for 
the Erlenmeyer filtering flask in connection with the ma- 
nometer. 

1 Pregl, Abderhalden's " Handbuch der biochemischen Arbeitsmethoden," 
V (1912), 1332. See also Fisceman, Rend, accad.sci. fis. et mat. Napoli, [3], 21 
> 135-42. 



272 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

7. * Rubber pressure tubing (p. 283). 

8. * One U-tube, with ground glass stoppers, 12.5 cm. (5 inches) 

(p. 282). 

9. Glass beads for the U-tube (p. 282). 

10. *One porcelain or quartz boat (pp. 284, 292). 

11. * One special weighing tube, boat tube (" piggie ") (p. 251). 

12. Azotometer, 50 cc., graduated to o.i cc., and reservoir 

(p. 285). 

13. Carbon dioxide generator (p. 275), consisting mainly of: 

a. Erlenmeyer filtering flask, 750 cc. 

b. Dropping-funnel, 200 cc. 

c. Stout safety bottle, about 200 cc. 

d. Bulbed test-tube, 6 inches. 

e. Capillary tube. 

14. Seven stop-cocks. 

15. Erlenmeyer filtering flask (in connection with manometer) 

(p. 282). 

16. Manometer stand (p. 281). 

17. One length of glass tubing for manometer, about 140 cm. 

18. Water pump or oil vacuum pump (p. 282). 

19. Thermometer (p. 298). 

20. * Crucible tongs. 

21. * One pair of pliers. 

22. * Desiccator. 

23. Mercury, 450-500 grams (pp. 275, 281, 286). 

24. One test-tube of Pyrex glass, for the reduced copper spiral 

(p. 285). 

25. Glass wool or asbestos for the above (p. 285). 

26. * Stop-cock grease, E. & A. (p. 283). 

Chemicals 

1 . 100 grams of cupric oxide, wire form. 

2. Pure sodium bicarbonate, 100 grams for each determination. 

3. Cone. s\ilfuric acid, for use in generator and U-tube. 

* Those pieces of apparatus which are starred (*) are the same as on the list 
for the carbon and hydrogen determination and given on pp. 223-4. 



ORGANIC COMBUSTIONS 273 

4. Potassium hydroxide (100 grams dissolved in 100 cc. water 
makes a solution which is good for two determinations). 

III. Topical Outline of General Method of Procedure 

1. Set up the electric combustion furnace (p. 283). 

2. Select the combustion tube, and if necessary cut to proper 

length and " round " the edges (p. 284). 

3. Fill the combustion tube (p. 284). 

4. Assemble the carbon dioxide generator (p. 275), the manom- 

eter (p. 281), and accompanying stop-cocks and U-tube 
(p. 282). 

5. Clean, attach and test the azotometer (nitrometer), (p. 285). 

6. Prepare the carbonate mixture and i : i sulfuric acid for the 

generator (p. 277), and the mercury and the i : i potas- 
sium hydroxide solution for the azotometer (pp. 286-7). 

7. Prepare the cupric oxide wire in the combustion tube by 

heating it under diminished pressure and allowing it to 
cool in an atmosphere of carbon dioxide (p. 288). 

8. Test the entire apparatus (p. 293). 

9. Prepare the reduced copper spiral and allow it to cool (p. 285). 

10. Weigh out the substance (p. 292). 

11. The combustion proper (p. 294); the furnace can be cold or 

hot at the beginning (p. 294). 

a. Insert the boat containing the substance (pp. 294-5). 

b. Insert the reduced copper spiral (pp. 294-5). 

c. Connect up the entire apparatus, evacuate, and flood 

with carbon dioxide (p. 295). 

d. Heat the reduced copper spiral to redness for about 

five minutes in order to drive out occluded gases 
(P- 295). 

e. Test with azotometer full of the potassium hydroxide 

solution to see if all non-absorbable "gases have 
been removed from the apparatus, or reduced to 
a minimum (pp. 295-6). 

/. Heat the layer of cupric oxide wire to redness, being 
careful not to burn the substance (p. 295), and at 
the same time 



274 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

g. Reduce the flow of carbon dioxide to such an extent 
that it will just keep the products of combustion 
moving toward the azotometer, using the stopper 
in the U-tube for regulating the gas (p. 28-2), 
and allowing the excess of carbon dioxide to escape 
through No. 2 (p. 276). 

h. Slowly heat the oxidized copper spiral, and then com- 
bust the substance (p. 296). 

i. Drive over all the remaining nitrogen gas with carbon 
dioxide by gradually increasing its flow (p. 297). 

j. Close stop-cock No. 6 (between the azotometer and 
the combustion tube), wash the gas in the azotom- 
eter with one portion of the potassium hydroxide 
solution, while the reservoir is in the low position 
(I), and then wash with cold distilled water, which 
has been recently boiled to drive out dissolved air, 
until all the potassium hydroxide solution is out 
of the azotometer and the reservoir (p. 297). 

k. Level the liquid in the reservoir and the azotometer, 
place a thermometer in the water in the top of the 
azotometer, and after twenty to thirty minutes 
record the volume of the gas by reading the lower 
meniscus, the temperature, and the corrected 
barometer reading (p. 298). 

/. Calculate the percentage of nitrogen (p. 300). 

12. In order to have the tube ready for another combustion, 
remove the reduced copper spiral, draw air through the 
tube while it is still hot in order to oxidize the copper that 
has been reduced in the combustion, then flood the appa- 
ratus with carbon dioxide. Now it may be used again 
at once, or it can be closed off and the cupric oxide allowed 
to cool in the atmosphere of carbon dioxide (p. 299). 



ORGANIC COMBUSTIONS 275 



IV. The Apparatus and How to Put it together, with Notes on 

Manipulation 

i. The Carbon Dioxide Generator. Since the substance is 
burned in an atmosphere of carbon dioxide and since the nitrogen 
gas itself is measured directly, the carbon dioxide must be as free 
as possible from any impurities which will not be absorbed by 
the potassium hydroxide solution in the azotometer. The car- 
bon dioxide can be prepared from sodium bicarbonate l or from 
normal potassium carbonate. On account of the expense in- 
volved in the use of the potassium carbonate, the sodium bicar- 
bonate is generally used and unless otherwise stated is always 
referred to in the following discussion. The same style of 
generator can be used in either case. 

The generator must be one that can be used with pressures 
above or below atmospheric. Many are the styles of generators 
that have been used and published,* and the one described herein 
contains no new features. It has simply been selected as one 
that can easily be assembled from ordinary apparatus. At the 
end of this chapter an innovation is described in connection with 
the stop-cock (see p. 278). 

A glance at the general diagram* of apparatus, Fig. 20, 
shows that an Erlenmeyer filter flask (about 750 cc.) is sur- 
mounted by a dropping-funnel of about 2oo-cc. capacity. In 
order to equalize the pressures in the two chambers an outside 
connection is made from the top of the dropping-funnel through 
stop-cock No. ii 2 to the top of the filter flask. A three-holed 
rubber stopper is used in the filter flask and the third hole is con- 
nected with a stout empty bottle and this with a stop-cock (No. 
2) leading into a bulbed test-tube containing about 8 cc. (108 

1 Sodium bicarbonate was chosen by Bradley and Hale (Journ. Amer Chem. 
Soc. t 30 (1908), 1090) who prepared carbon dioxide which was of extreme purity 
containing only one part of impurity (that is, gas not absorbed by potassium hydrox- 
ide solution) in 30,000 to 40,000 parts of the gas. 

2 Stop-cock No. ii is added to close off the acid and prevent it from absorbing 
COa from the lower chamber and forming a partial vacuum. This is particularly 
true in the case of potassium carbonate when that is used. It is also added in 
order that the reservoir of the dropping-funnel may be recharged without allowing 
much air to get into the lower part of the generator. 



276 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

grams) of mercury. This acts as a safety outlet for the excess 
of carbon dioxide. Generally the tube from the stop-cock should 
dip about 3.5-4 cm. into the mercury. The bulb in the test- 




tube prevents the mercury from splashing out of the tube. The 
top of the test-tube should be loosely packed with cotton to 
prevent fine particles of mercury from being thrown out. The 
empty bottle serves as a safety bottle to prevent any of the 
mercury from being drawn into the generator in case the stop- 
cock is not closed at the proper time. Whenever carbon dioxide 



ORGANIC COMBUSTIONS 277 

is being passed through the apparatus under its own pressure, 
stop-cock No. 2 should always be left open in order that any 
excess of pressure can be taken care of. 

A capillary tube, i mm. inside diameter, bent upwards at the 
lower end, is attached to the stem of the dropping-funnel, 1 and 
is arranged to deliver the acid beneath the surface of the bicar- 
bonate mixture. This insures a more even generation of carbon 
dioxide and better control than when the acid is allowed to drop 
from the stem. The upward bend prevents the carbon dioxide 
from going up the stem of the dropping-funnel. Modifications 
will, of course, suggest themselves to each operator for his con- 
venience. 

One hundred grains of pure sodium bicarbonate and 100 cc. of 
recently boiled and cooled water are used as a single charge for the 
generator. This is not enough water to dissolve all the bicar- 
bonate, but is sufficient for the purpose. The bicarbonate mixture 
should be removed and fresh material put in after each combustion. 
Otherwise the supply of carbon dioxide may fail at a critical time 
when there is no possibility of making the change. One hundred 
and fifty cc. of a mixture of one part of cone, sulfuric acid and 
one part of distilled water in the dropping-funnel will serve for 
at least two combustions. 

Sodium bicarbonate and water react to give carbon dioxide 
even at the ordinary temperature, and at elevated temperatures 
the bicarbonate is rapidly converted into the normal carbonate. 
Reduction of the pressure produces the same reaction at lower 
temperatures, as will be noticed during the operation. 

Potassium carbonate has an advantage over sodium bicar- 
bonate as a source of CO2 in that it can be used in a fairly con- 
centrated solution. The solution of the carbonate is made up 
with a specific gravity (1.45-1.5) somewhat greater than that 
of the sulfuric acid (1.4) and the carbonate solution is put into 
the dropping-funnel instead of the filter flask of the generator 
described above. The carbonate solution of sp.gr. 1.45-1.5 

1 The joints should be wired, since the rubber gradually swells and becomes 
loose. 



278 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

contains 43-47 per cent of potassium carbonate and is prepared 
by dissolving about 85-90 grams of dry pure normal potassium 
carbonate in 100 cc. of recently boiled water, and the sulfuric 
acid solution is prepared by mixing 100 cc. of cone, sulfuric acid 
and 100 cc. of water. The relative specific gravity of the 
carbonate solution, when cold, can be tested if a hydrometer is 
not at hand by seeing if a drop of brombenzene (1.496/16) 
or of chloroform (1.498/15) sinks and a drop of ethyl bromide 
(1.468/13) just floats in it, provided, of course, the influence of 
surface tension is guarded against by stirring. Since the car- 
bonate solution dissolves carbon dioxide with the formation 
of the bicarbonate which is much less soluble than the normal 
carbonate and crystallizes out, and since this absorption produces 
a partial vacuum, the surface of the solution should be covered 
with a thin layer of petroleum oil 1 to prevent access of the 
carbon dioxide to the liquid. 

A generator with a special stop-cock 2 for dropping the liquid 
arranged for equalizing the pressure above and below the outlet 
in the stop-cock is shown in Fig. 21. The equalizing is done 
through a connection made by means of the annular groove 
in the key of the stop-cock. No matter which position the 
key occupies there is always communication between the atmos- 
phere in the lower flask and that in the upper flask. One 
arm of the stop-cock is extended until it opens above the liquid 
in the upper container. No outside connection is necessary. 
The liquid enters at an aperture in the lower part of the ex- 
tended arm and is delivered through a small glass tube sealed in 
at this opening. Two styles of stop-cocks are shown in the 
diagram, using the same general principle in each. 

If the flasks are used as shown they must be securely fastened 
by clamps close to the lips. The upper flask can be filled through 

1 Compare Watson Smith, Jr., " Quantitative determination of the carbonyl 
group in Aldehydes, Ketones, etc." Chem. News, 93 (1906), 83; where paraffin oil 
is used to protect Fehling's solution from absorbing carbon dioxide. Also given 
in H. Meyer, " Analyse und Konstitutionsermittelung organischer Verbindungen," 
2. Auflage, p. 683. 

2 Fisher, Journ. Ind. and Eng. Chem., 10 (1918), 1014. 



ORGANIC COMBUSTIONS 



279 



a funnel attached by means of a piece of rubber tubing. The 
liquid will flow down the inside walls and not drop into the ex- 



Fig, la 





Figf. 1 

Reproduced, with permission, from the Journal of Industrial and Engineering Chemistry. 

FlG. 21. 

tended tube. The arrangement and kind of flasks can be changed 
as desired. 



280 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

FURTHER NOTES AND REFERENCES 

F. Blau l used the potassium carbonate and sulf uric acid as de- 
scribed above. He found that 50-100 cc. of the carbonate solution 
was needed to drive the air out of the apparatus and only about 20 cc. 
was needed for the combustion proper. This latter amount in a 
blank run yielded only 0.07-0.1 cc. of unabsorbed gas in the azotom- 
eter, and the author's experience has been similar. Blau remarks 
that it is not necessary to boil the concentrated carbonate solution 
since it absorbs a much smaller amount of air than an equal volume of 
water and only a small volume is used. He adds that a more dilute 
solution cannot be used without having been boiled, since it absorbs 
a large amount of air and moreover greater amounts of the solution 
must be used. 

Young and Caudwell 2 used potassium carbonate also in their 
generator. They found that " the carbon dioxide formed in this 
manner does not contain o.i cc. of air per 5 litres," which means an 
impurity of less than i part in 50,000 (compare below and p. 275). 
Fieldner and Taylor 3 used this method, and state that " there was 
little difficulty in clearing the cold tube of air so that the CO2 was 
completely absorbed," and yet in reply to a letter from the author, 
Dr. Fieldner said that they tried three samples of potassium carbon- 
ate before they obtained carbon dioxide that gave only a minimum 
of tiny bubbles which were never totally absorbed. 

The purest carbon dioxide that has ever been obtained and 
accurately analyzed and recorded was prepared by Bradley and Hale 4 
in connection with work on physical constants of the gas. They 
used sodium bicarbonate in the form of a paste and cone, sulfuric 
acid. In guarding against impurities from the air they found it 
even necessary to place mercury jackets around all rubber connec- 
tions since air diffuses in as well as carbon dioxide diffuses out through 
the rubber. In their article other recorded attempts to prepare pure 
CO2 are given and discussed. 

Sodium bicarbonate in the form of dry powder has been used 
in connection with nitrogen determinations in the open-tube method. 

1 Monatshefie fur Chemie, 13 (1892), 277. 

2 "Apparatus for the Supply of Carbon Dioxide in the Determination of 
Nitrogen in Organic Compounds by the Absolute Method," Journ. Soc. Chem. 
Ind., 26 (1907), 184. 

3 Journ. Ind. and Eng. Chem., 7 (1915), 109. 

4 Journ. Amer. Chem. Soc., 30 (1908), 1090. 



ORGANIC COMBUSTIONS 281 

It is heated in a separate tube. Dennstedt 1 selected this substance 
for his work. Gattermann 2 also describes how to use it. However, 
it is difficult to handle and contains occluded air. 

Thudichum and Wanklyn 3 recommend a mixture of potassium 
bichromate and sodium carbonate for yielding carbon dioxide by 
direct heating. 

Magnesite (MgCOa) is used as the source of CO2 in the closeg 1 - 
tube method 4 (see p. 270), but it usually contains small amounts 
of occluded air. 

Carbon dioxide from a Kipp generator cannot be used even when 
the marble lumps have been boiled with water on account of the 
occluded air. 

The tanks of liquid C02 as obtained on the market contain con- 
siderable amounts of air and therefore cannot be used. 

2. The Manometer, Accompanying Stop-cocks, U-tube, etc. 

Since diminished pressures are used in the nitrogen determina- 
tion, it is necessary to have a manometer in connection with 
the apparatus in order that the operator will be able to under- 
stand what to do. The U-form is recommended as shown in the 
general diagram (p. 276). It is made of ordinary glass tubing 
and is attached to a wooden stand provided for this purpose. 
The long arm should be at least 82 cm. in length and the short arm 
at least 55 cm. The short arm is surmounted with an inverted 
small test-tube with a plug of cotton at the bottom to prevent dust 
particles from getting into the tube and to prevent mercury from 
splashing out. With the ordinary glass tubing of about 5 mm. 
bore, approximately 250 grams of mercury is required. The 
column of mercury when at rest should extend in each arm 
40-41 cm. from the lower bend. If it is much higher than this, 
it may be drawn over the top when a good vacuum is being 
obtained. A meter stick may be attached to the board to 
measure the difference in heights of the two columns, 5 if the actual 

1 Dennstedt, " Anleitung zur vereinfachten Elementaranalyse," 3 Auflage, 129. 

2 Gattermann, " Practical Methods of Organic Chemistry," trans, by Schober 
and Babasinian, 3d Amer. Ed. (1914), p. 101. 

*Journ. Chem. Soc. t 22 (1869), 293. 

4 Gattermann, loc cit., p. 94. 

5 Or short paper scales can be used. Select any point, #, not less than 38 cm. 
above the lowest bend in the glass tubing, and attach a narrow strip of paper near 



282 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

pressure is desired. The pressure within the apparatus may be 
calculated by subtracting this difference in height from the 
barometer reading at the time. 

The manometer is connected with an Erlenmeyer heavy- 
walled filtering flask and this is provided with an outlet stop- 
cock (No. 9) and another stop-cock (No. 10) leading to a suitable 
pilmp. When a water pump is used the connection is made 
to go to the bottom of the filtering flask in order that any water 
which may come over on account of unequal pressure in the 
water main will be sucked right out as soon as the greater water 
pressure returns. A good water pump will give a pressure in the 
apparatus as low as the vapor tension of the water at its par- 
ticular temperature. In winter when the temperature of the 
water may be 8, at which the vapor tension of the water is 7.99 
mm., the pressure within the apparatus may approach 8 mm., 
but in summer when the temperature of the water may be as 
high as 23 a pressure cannot be obtained lower than 21 mm., 
which is the vapor tension of the water at that temperature. 
A good oil pump can be substituted for the water pump with 
much advantage. 

The outlet of the Erlenmeyer filtering flask is connected by 
means of a stop-cock (No. 8) to a T-tube which joins the genera- 
tor and a U-tube with ground stoppers. The U-tube is filled 
with glass beads and just enough cone, sulfuric acid is added to 
make a seal at the bottom and no more. The glass beads serve 
to prevent the acid from being splashed upon the stop-cocks. 
The acid attacks the grease and causes leakage as well as sticking 
of the stoppers. The acid is used to prevent an excess of moisture 
from the carbon dioxide from getting into the combustion tube 
and it also shows which way the gases are flowing. The amount 

the top and one near the bottom of the stand. Measuring from the point x, mark 
on the papers numbers showing 28 to 38 cm. up and down, respectively. The 
numbers may vary according to the positions of the papers. Ruled centimeter 
paper is very convenient, and when this is used it should not be attached until 
a definite point opposite a centimeter line has been located. In order to calculate 
the pressure within the apparatus, add the numbers on the lower and upper scales 
opposite the top of the mercury meniscus and subtract the sum of these numbers 
from the barometer reading at the time. 



ORGANIC COMBUSTIONS 283 

of carbon dioxide flowing into the combustion tube is regulated 
by one of the stoppers (No. 5). 

All connections are made with short lengths of heavy-walled 
rubber " pressure " tubing. 

All stop-cocks should be carefully cleaned and greased with 
a good stop-cock grease, such as that prepared by Eimer & 
Amend, New York (see p. 229). Do not plug up the opening in 
the key with grease. Too much grease is worse than too little. 
Also do not use vaseline, since it has no " body." Great care 
should always be exercised in turning the keys in the stop-cocks to 
see that they fit tightly and do not leak. Never turn the key by 
using only one hand. Support the other side of the stop-cock 
with the other hand and use just a little pressure when turning 
the key. Fasten the keys with wire or twine, not with elastic 
bands, to avoid possible breakage (compare p. 229). The parts 
of all stop-cocks should be numbered in order that they will be 
properly assembled. 

An alternative method of preparing the manometer is to use 
a straight glass tube, about 85 cm. long, dipping directly into 
mercury. The bottle containing the mercury should be of such 
a size that when the excess of C02 is passing out of the tube the 
pressure will be all right for the conditions involved, that is, 
the layer of mercury through which the gas must pass will be 
somewhat greater than that in the azotometer. Otherwise the 
gas jwould pass out at this opening instead of going into the 
azotometer. The method has the advantage of less apparatus, 
but the pressure in the generator cannot so easily be regulated 
as in the method described above, and there is more space to be 
emptied of air and kept filled with CO2 all the time the combus- 
tion is being run, since stop-cock No. 8 cannot be shut off. 

3. The Electric Combustion Furnace. An electric com- 
bustion furnace of the multiple unit type is the most convenient 
furnace to use for heating the combustion tube in the deter- 
mination of nitrogen. The arrangement of the heating sections 
and the heat control should be the same as described for the 
carbon and hydrogen combustion (p. 230). 



284 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

NOTE 

Water formed in the reaction sometimes collects in the end of 
the combustion tube near the azotometer, especially if an extra long 
extension is used. Since the water is not needed no provision is 
made for getting rid of it. However, if it is allowed to collect, it 
will cause some combustion tubes to crack. In order to keep it 
from flowing back along the heated portion of the tube and causing 
the tube to crack, the tube may be slanted somewhat by blocking 
up the other end of the furnace 2-3 cm. above the level of the desk. 

4. The Combustion Tube and How to Fill It. The com- 
bustion tube itself should be the same in every way as the one 
described in connection with the determination of carbon and 
hydrogen (pp. 232-3). 

The method of filling is indicated in the general diagram 
(p. 276). An 8-cm. roll of cupric oxide gauze (see p. 235) is pre- 
pared and placed at A , near the end to which the U-tube is con- 
nected. It serves the same purpose as the one in the carbon 
and hydrogen combustion, that is, mainly as an " oxidation 
buffer " in preventing any gases which may go backward from 
getting so far back that the determination is spoiled (see p. 235). 

About 25 cm. from this same end of the combustion tube, place 
a short roll of copper gauze, fitting snugly; follow this with a 
layer of cupric oxide 1 in wire form, and keep this in place with 
another snugly fitting short roll of copper gauze. This entire 
layer, including the short " spirals " should measure approxi- 
mately 26 cm. The open space, B, between the long cupric 
oxide " spiral " and the long layer of cupric oxide, is reserved for 
the boat. 

For the far end of the combustion tube which is heated by 
section No. 3, prepare a i2-cm. roll of copper gauze, D. This is 
always used in the reduced condition in order that any oxides 
of nitrogen that may be formed will be converted into elemental 

1 Cupric oxide, which has been used for the determination of carbon and hydro- 
gen, can be used for the determination of nitrogen, although the opposite is not 
the case on account of the possible retention of carbon dioxide, unless it has been 
heated in the open for a long time and allowed to cool in the air. The cerium 
dioxide catalyst cannot be used in the nitrogen determination. 



ORGANIC COMBUSTIONS 285 

nitrogen before passing into the azotometer. The reduction is 
carried out as follows: Select a Pyrex test-tube of such a size 
that the roll of copper gauze will fit in it loosely. Place a wad 
of asbestos or glass wool at the bottom, add not more than 
i cc. of methyl alcohol, and support it in a stand. Heat the 
spiral to redness over a Meker burner or in a very large blast 
flame. In order to avoid melting the copper the lower end of the 
spiral is slowly swung to and fro while the upper end is securely 
held in its position by the little loop with a pair of tongs. In 
this way the entire gauze is evenly heated. Then quickly drop 
it into the test-tube, and ignite the issuing vapors. Do not 
breathe the fumes, since they consist largely of formaldehyde. 
If the heating has been done properly the copper soon looks 
beautiful in the reduced condition. When the flame dies down 
and just as it recedes into the tube, put in the cork loosely, and 
set aside until it becomes cold before placing the spiral into the 
combustion tube. If the tube is not stoppered, the hot spiral 
will be reoxidized as air follows the flame down the tube. 

5. The Azotometer. 1 The nitrogen is collected and measured 
in a Schiff azotometer. 2 It is illustrated in the general diagram 
on p. 276, and as shown it consists of a graduated tube sur- 
mounted with a stop-cock and extension cap, and near the bottom 
arranged as indicated for a gas inlet protected by mercury and a 

1 The term " azotometer " is used instead of " nitrometer," as the apparatus 
is sometimes called, since the latter refers more directly to the measurement 
of nitric oxide formed in the analysis of nitric acid by reduction with mercury 
in presence of sulfuric acid, while azotometer literally means the nitrogen measure. 
(French, azote; Greek, utrpov (metron)). Schiff speaks of it in his original article, 
Zeit. anal. Chcm., 7 (1868), 430, as an " azotometer." Lunge, Ber., 11 (1878), 
434, named his nitrometer from the fact that he desired it for analyzing " nitrose," 
which is defined by Patterson in his " German-English Dictionary for Chemists " 
as " a solution of nitrosylsulfuric acid in sulfuric acid, formed in the lead-chamber 
process." This material is known in English as " nitrous vitriol " and described 
in the " Century Dictionary " as " strong sulfuric acid charged with nitrosulphonic 
acid. It runs off from the bottom of the Gay-Lussac absorbing tower in the man- 
ufacture of sulfuric acid by the lead-chamber process." Lunge also mentions 
" Gay-Lussac-Thurm-saure " (Gay-Lussac tower acid). Compare also Lunge, 
" Technical Methods of Analysis," trans, by Keane (1908), Vol. T, Pt. I, 125 and 

131- 

2 Schiff, Zeit. anal. Chem., 7 (1868), 430. 



286 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

connection by means of a rubber tube to a reservoir which holds 
the solution of potassium hydroxide. An adjustable ring (not 
shown in the diagram) is attached for holding the reservoir in 
any position desired. The tube proper should be about 7-8 mm. 
inside diameter, 48 cm. long (measured from the reservoir outlet 
to the stop-cock) with a capacity of 50 cc. of gas and gradu- 
ated in one-tenths. Enough mercury (about 10 cc. or 135 
grams) should be put into the bottom to make a good seal for 
the inlet tube l but not enough to splash over into the tube lead- 
ing to the reservoir. The distance between these inlet and 
outlet tubes should be not less than 3 cm. Furthermore the inlet 
tube should be bent upwards to such an extent (about 8 cm.) 
that the mercury will not run over when the reservoir full of KOH 
solution is raised to the top of the azotometer. 

Some azotometers are made without the cup sealed on top, 
but have a narrow tube for connecting with a eudiometer for 
transferring the gas. A cup can be put on one of this type 
by attaching a wide tube by means of a rubber stopper. Some azo- 
tometers are provided with water jackets, but it does not appear 
necessary to use this for general work. 

The stop-cock should be well ground and all directions given 
for handling stop-cocks should be used in handling this part 
of the azotometer (see pp. 229 and 283). Be sure that all 
parts of both key and barrel are dry before putting on the 
grease. Except when the apparatus is actually in use the key 
of the stop-cock should not be allowed to remain in its proper 
position, since it is very likely to become " frozen " even on 
standing overnight if there is any of the potassium hydroxide 
solution in the grease. 2 Attach it with a piece of twine. 

1 Dennstedt in his " Anleitung zur vereinfachten Elementaranalyse," 3 Auflage, 
125-8, describes a modified azotometer which has a capillary inlet tube ending in an 
internal projection which delivers a fine stream of gas, and which also has an en- 
larged portion below the graduated part to serve as a reservoir in case a large 
amount of gas is suddenly delivered into the azotometer. 

2 An excellent method of removing " frozen " stop-cocks is given by V. C. 
Allison, Journ. Ind. and Eng. Chem., 11 (1919), 468. The handje of the key is 
slipped into a socket in a block of hard wood while the opening of the block rests 
as a collar on the shoulder of the barrel of the stop-cock. A plug of wood is placed 
against the other end of the key, and easy regular pressure brought to bear by 



ORGANIC COMBUSTIONS 287 

The potassium hydroxide l solution is prepared by dissolving 
100 grams of solid potassium hydroxide in 100 cc. of water. 
Since much heat is developed a porcelain or quartz casserole 
should be used. The solution should be clear and free from 
foreign particles. It can be filtered through an ordinary wet 
fluted 2 filter paper if the solution is added slowly. The amounts 
given are sufficient for the azotometer described above, and are 
enough for at least two " runs." The solution may become col- 
ored from contact with the rubber tubing but this seems to do 
no harm. 

The mercury can be purified by washing, and then, after 
removing most of the water, filtering it through a dry filter paper 
containing a few tiny holes in the bottom. Repeat several times 
if necessary. 

Testing the Azotometer. Clean it thoroughly, properly 
grease the stop-cock, and add the mercury and the potassium 
hydroxide solution. Attach stop-cock No. 6, open it and also 
No. 7, the one on the azotometer (see general diagram, p. 276). 
Lift up the reservoir slowly from position I to position II, and note 
the rise of the mercury in the inlet tube. It should not go into 
the tube of the stop-cock, although this will do no particular 
harm, but it should never go beyond the stop-cock. Lower the 
reservoir until there is 4-5 cc. of air in the tube, then close the 
stop-cock (No. 7). Now lower the reservoir to position I and 
after allowing two to three minutes for drainage take the reading 
and record it. Allow the apparatus to stand for twenty to 
thirty minutes, take the reading under the same conditions, 
and compare with the previous reading. If there is no decided 
change and no chance for temperature fluctuation, the stop- 
cock is tight, but if the volume has increased there is something 
wrong with the stop-cock or with the greasing. 

means of a vise. Different sizes are given for the ordinary stop-cocks in use. The 
scheme is rapid and it works! 

1 Sodium hydroxide cannot be used, since the carbonates formed crystallize out 
and cause much trouble. 

2 See foot note, p. 128. 



288 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

V. The Final Preparation of the Cupric Oxide l 

Cupric oxide when heated and cooled in an atmosphere of 
oxygen or air adsorbs some of these gases. The cupric oxide thus 

1 NOTES AND REFERENCES 

Cupric oxide has been used in organic combustions for the determination of 
carbon and hydrogen and nitrogen since 1815 (see p. 218), and the method for 
determining nitrogen separately was worked out especially by Dumas in 1831 (see 
p. 269). That cupric oxide absorbs gases and gives them up on heating was noticed 
as early as 1842, when Erdmann and Marchand, J.filr prakt.Chcm.,26 (1842), 466-7, 
working " On the atomic weight of hydrogen," showed that 100 grams of cuprk 
oxide when heated in an atmosphere of carbon dioxide after " pure carbonic acid " 
had been passed through the tube for many hours, gave 5.5. cc. of air unabsorbcd 
by potassium hydroxide solution. In 1868 Frankland and Armstrong, in an 
article " On the Analysis of Potable Waters," /. Chcm. Soc., 21 (1868), 89 and 93, 
described their method of determining carbon and nitrogen in very small amounts 
of organic material by burning it in a combustion tube after complete evacuation 
with a Sprengel pump and analyzing the gases evolved. They state, " Cupric 
oxide prepared from the nitrate should on no account be used, since, even after 
being actually fused, it evolves considerable quantities of carbonic anhydride and 
nitrogen when ignited in vacuo" Eight years later Thudichum and Kingzett, 
/. Chem. Soc., 30 (1876), 363, confirmed these findings in general. Hilditch, 
Chem. News, 49 (1884), 37, mentions the fact that cupric oxide occludes air, and 
Morley, Amer. J. Set., 41 (1891), 281, shows that cupric oxide slowly gives off 
gas in a vacuum. T. W. Richards, in revising the atomic weight of copper, Proc. 
Amcr. Acad. Arts and Set., 26 (1891), 281, and Zeit. anorg. Chcm., 1 (1892), 196; 
proved that several of the former 1 y accepted results were incorrect on account of 
the error involved due to gas adsorbed by the cupric oxide which had been used for 
the determinations. In his later systematic work on this particular subject, " On 
the Cause of the Retention and Release of Gases occluded by the Oxides of 
Metals," Amcr. Chcm. /., 20 (1898), 701, he states (page 711), " When the im- 
prisoned gas (in cupric oxide) has once begun to be set free, at temperatures above 
850, the time is an essential factor, and that when sufficient time has been allowed, 
the expulsion of the gas is almost complete." Furthermore (p. 727), " Two grams 
of cupric oxide, which had been ignited for a long time in pure air until constant 
in weight, were found to evolve a gas steadily when heated in a vacuum to about 
the melting-point of common salt (790), provided that the gas was removed by 
a Sprengel pump as fast as it was formed." Cupric oxide begins to lose " struc- 
tural oxygen " even in the air at about 1000, but this is above the melting-point 
of the hard glass used. Cuprous oxide was found in the residue. The observation 
is then made (p. 728): 

" Since cupric oxide is slightly dissociated by heat, perceptible amounts of 
oxygen should be removed by heating it in nitrogen, just as carbonic acid is removed 
from limestone by heating it in a current of air. This dissociation of cupric oxide 
must have its effect on any process involving the ignition of cupric oxide in a 
vacuum or in an inert gas. The determination of organic nitrogen by means of the 
Sprengel pump, for example, must be affected by it. The use of carbon dioxide 



ORGANIC COMBUSTIONS 289 

prepared on being heated again slowly gives off the adsorbed gas. 
Since the gas which is slowly given off is not absorbed by the 

as a displacing medium in the Dumas method, probably disposes of the error, 
however, for carbon dioxide is itself dissociated by heat, and it undoubtedly fur- 
nishes enough oxygen to diminish greatly the decomposition of the cupric oxide." 
(NOTE. It should be emphasized that this latter statement refers only to 
the liberation of gas from the actual decomposition of the cupric oxide and not 
to the liberation of occluded gases.) 

The gas occluded in the cupric oxide is only slowly given off by heating to 
redness, and the error involved in the nitrogen determination amounts to +0.2 to 
0.5 per cent 1 (usually nearer the higher figure) when 0.2 gram of the .sample is 
used. Diminishing the time of the combustion of course diminishes this error, 
and usually there are compensating errors, which vary a great deal, in general 
practice which also sometimes keep the final error down to the ordinary amount, 
that is, 0.2 per cent. When a substance with a high content of nitrogen is analyzed 
the " percentage error " is of course decreased, but with a low content of nitrogen 
it is very serious. None of the text-books on practical organic chemistry to which 
one would ordinarily go for a description of the Dumas method, such as those by 
Gattermann, W. A. Noycs, and J. B. Cohen, say anything about this error, 
Neither is it mentioned by Clarke, " A Handbook of Organic Analysis;" King- 
scott and Knight, " Quantitative Organic Analysis; " nor even by Lassar-Cohn 
" Arbeitsmethoden," allgemeine Teil, 4 Auflage (1906); and Weyl, " Die Method- 
en der organischen Chemie," allgemeine Teil (1909). All these authors do 
generally speak of the " minimum amount of foam " that always collects in the 
top of the azotometer and which Thudichum and Kingzett, /. Chcm. Soc., 30 
(1876), 366, characterized as " that obstinate bubble in the gas-tube which has puzzled 
so many of the best experimentalists." 

In 1915 Ficldner and Taylor, J. Ind. and Eng. Chem., 7 (1915), 106, attempted 
to check up their results of the analysis of some samples of coal for nitrogen, made 
by modifications of the Kjeldahl method, with the Dumas method since " it is 
generally regarded as fundamental and applicable to most classes of organic com- 
pounds." Since the coal contained only very small amounts of nitrogen, approxi- 
mately i per cent, they naturally tested their apparatus and method, as given in 
the usual references, by blank runs, and found what many others have also found, 
that varying amounts of gas were given off, for example, 6.6 cc. after six hours' 
heating followed by i .4 cc. when the tube was re-heated the next day. They then 
noted the following remarks by H. Meyer in his " Analyse und Konstitutionsermit- 
telung organischen Verbindungen," 2 Auflage (1909), 187, " The chief source of 
error lies in the impossibility of freeing the fine copper oxide from air, and 
therefore most of the results are too high by o.i to 0.2 per cent." Also, in Fre- 
senius-Cohn, " Quantitative Chemical Analysis," 6th Ed., II (1904), 68, "The 
results are generally somewhat too high, viz., by about 0.2 to 0.5 per cent," and 
that in a blank experiment with sugar the quantity of unabsorbed gas " should 
not exceed i or 1.5 cc." H. N. Morse, " Exercises in Quantitative Chemistry" 
(1905), provides in part for the difficulty by heating both coarse and fine cupric 
oxide for ij hours at full red heat in a current of oxygen which is followed, without 
1 F. Blau, Monatschefle, 13 (1892), 277. 



290 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

potassium hydroxide solution in the azotometer. it causes a 
serious error in the determination of nitrogen. 

To prepare the cupric oxide for the analysis, it must be 
heated strongly to a good red heat, just as in the combustion 
itself, in a vacuum for about six hours, the gases being removed 
and replaced by " flooding " the apparatus two or three times 
with pure carbon dioxide. Finally the cupric oxide is allowed to 
cool in an atmosphere of pure carbon dioxide. In this manner 
the gas adsorbed is one that will cause no trouble in the analysis. 

After the entire apparatus 1 is set up and the generator 
properly filled, according to the description in Chapter IV, p. 275, 
set the stop-cocks as follows: Nos. i, 2, 6 and 9 closed, and 
3, 4, 5, 7, 8, 10, and n open; then turn on the pump, and also 
begin the heating. It is not necessary that the heating be done 
without interruption, but if it is interrupted the cupric oxide 
must be allowed to cool in an atmosphere of carbon dioxide, 
otherwise little will have been accomplished. 

Soon after the apparatus has been evacuated, occluded and 

cooling, by carbon dioxide for an hour or more, and the oxide is allowed to cool 
in CO2. Finally in an obscure journal, in an article published in 1898 by F. C. 
Phillips, on the " Fluctuation in the composition of Natural Gas," Proc. Eng. Soc. 
Western Pa., 14, 299, they found an account of similar difficulties overcome: " In 
beginning a series of determinations several days were often required for the purpose. 
The porcelain tube was strongly heated, while a slow stream of carbon dioxide was 
maintained; the CuO was not considered to be in proper condition until the 
escaping COg was absorbed without residue. It was found that the CuO when 
once impregnated with CO-2, while strongly heated, could be rcoxidized by air cur- 
rent with little tendency to occulsion of air, but if the copper oxide was allowed to 
cool in contact with air much time was lost in removing the air by carbon dioxide 
even when strong heat was applied." Fieldner and Taylor then proceeded to 
shorten the time for the final preparation of the cupric oxide by heating it in 
vacua. It is well worth one's while to go over their recorded experiments as 
given in their original article mentioned above. They concluded that, " Errors in 
the Dumas method due to nitrogen from the CuO were minimized by previously 
heating the oxide for several hours in vacua, cooling it in COz, and using * wire 
form ' oxide pulverized to pass through a 40-mesh screen and remain on 100 mesh." 
These results are incorporated in the present work. 

1 The boat filled with CuO wire should be in place (p. 284), but the reduced 
copper spiral should, of course, not be in the tube during the preliminary heating 
(pp. 294-5). Also, it is not absolutely necessary to have the azotometer attached 
at this time. 



ORGANIC COMBUSTIONS 291 

dissolved air and finally some CO2 will begin to come out of the 
materials in the generator. In order to help get rid of as much 
air in the generator as possible, allow a little swlfuric acid to 
flow into the carbonate mixture. After the vacuum has been 
maintained for about half an hour, close No. 3 and leave the gen- 
erator under these conditions until you are ready to flood the 
apparatus with CO2. 

To flood the apparatus with CC^: Close No. 10, then turn 
off the pump. If No. 3 has been closed during the heating, 
gradually open it. The mercury in the manometer will fall 
somewhat. Now allow the sulfuric acid to flow slowly into the 
carbonate mixture. 1 Carefully watch the fall of the mercury, 
and when the two columns are level quickly open No. 2 in order 
that the excess of CC>2 may pass out. By opening No. 6 (leaving 
No. 7 open also if the azotometer is attached) the gas can sweep 
out the entire apparatus. Then close No. 6 and No. 3, turn on 
the pump, and open No. 10, and continue the heating as before. 

When the six hours' heating is at an end, flood the apparatus 
once again in the same way as before, making certain that No. 2 
has been closed before No. 3 is opened. Now turn off the heat 
and allow the cupric oxide to cool in the atmosphere of CCb. 
The tube may be left alone to cool after closing Nos. 5 and 6 
If you have time, pass CO 2 through the tube while it is cooling, 
but this is probably not necessary. When you leave the appa- 
ratus for the night, see that Nos. 5, 6, i, 2, 10, and u are closed; 
and that 3, 8, and 9 are open. 

In order to avoid contaminating the carbon dioxide in the 
generator with air from possible leaks when the generator is 
under diminished pressure, it is well to keep it under a little 
pressure practically all the time and especially during the combus- 
tion, allowing the excess to pass out through stop-cock No. 2 
and the mercury trap. By exercising a little care you will find it 
possible to keep the generator under pressure even when connect- 
ing it with the apparatus that has been evacuated. After stop- 
cock No. 10 has been closed and while a good stream of gas is 

1 Too much acid at one time will cause the mixture to foam over into other 
parts of the apparatus. 



292 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

going out through the mercury trap, partially open stop-cock 
No. 3, watching the overflow all the time. As soon as the 
mercury begins to rise in the outlet tube close stop-cock No. 3, 
and then gradually open it again. Frequent glances at the 
manometer will show how the operation is going on. In this 
way the apparatus will soon be filled with carbon dioxide and 
the generator always kept under pressure and free from con- 
taminating air. 

After the cupric oxide has been heated and cooled in CO2, 
it can be handled in the open but not without adsorbing air that 
will cause a small error. For example, Fieldner and Taylor 1 
found that when 100 grams of the cupric oxide " was subjected 
to alternate vacuum and carbon dioxide for several hours at 
850 C., until no further nitrogen was evolved, and was then 
cooled in CCb, exposed to air and again heated, the 40-100 
mesh 'wire ' oxide gave off only 0.7-0.9 cc. of nitrogen, while 
the 2oo-mesh material gave off 1.9-2.2 cc." 

When a combustion has been run it is necessary to reoxidize 
some of the copper, and have it ready for another determination. 
Before turning off the heat (or after allowing to cool in 62), 
remove the reduced copper spiral, and while the tube is hot pass 
air or oxygen through it until all the copper has been oxidized. 
Then while the tube is still hot, replace the air or oxygen with 
pure COo in the usual manner, keeping up the passage of the 
carbon dioxide for an hour, and allow to cool in the atmosphere 
of CO2 while the tube is closed. It is not necessary to heat again 
for six hours as is the case when the cupric oxide has been cooled 
in air 

VI. Weighing the Substance 

The substance is weighed in a porcelain or quartz boat inside 
the special boat tube (" piggie ") and all precautions as to 
moisture, state of division, etc., mentioned in connection with 
weighing the substance for the carbon and hydrogen determina- 
tion must be observed in this case also (see p. 252). After the 
substance has been weighed, and the weight recorded, it is not 
1 Journ. Ind. and Eng. Chem., 7 (1915), m. 



ORGANIC COMBUSTIONS 293 

essential in most cases that moisture be so rigidly excluded as 
for the carbon and hydrogen determination. However, it is! 
unfortunate for one to let down on the good practice of keeping 
moisture from weighed samples, and thus spoil a good habit. 

The amount of substance used should ordinarily be about 
0.2000 gram. If the nitrogen content is approximately known, 
use enough substance to give about 15-20 cc. of nitrogen. Some 
substances have a high percentage of nitrogen, and 0.2 gram 
would give more nitrogen than the azotometer could hold. Then 
the amount of sample should be cut down accordingly. Cor- 
respondingly, the amount of sample of a substance with a very low 
content of nitrogen should be increased, even to 0.5 gram, if 
necessary, and provided this much can be spared. 

VII. General Method of Procedure for the Combustion Proper 

Testing the Apparatus. After the cupric oxide has been 
prepared and the tube filled with carbon dioxide as already 
described (p. 288), test out the entire apparatus to see if the 
cupric oxide is all right, the carbon dioxide is pure enough, and 
all joints are in good condition. Have all of the apparatus con- 
nected and heat the combustion tube as for a regular combustion. 
Pass carbon dioxide through it and into the azotometer for five 
to ten minutes. 1 In order not to exhaust the potassium hydrox- 
ide solution, drop the reservoir to position I, and have stop-cock 
No. 7 in the azotometer open. At the end of the time specified, 
while the gas is still passing, carefully raise the reservoir to posi- 
tion II when the solution will flow through the stop-cock and 
into the cup on top. Now close the stop-cock and slowly lower 
the reservoir to its former position in order to reduce the pres- 
sure against the inflowing gas. Pass the gas through at a fair 
rate for about five minutes. The bubbles should not be so large 
and come so fast that they fill the entire azotometer tube and force 
all the potassium hydroxide solution into the reservoir. After 
the five minutes note whether the volume of unabsorbed gas 
which collects at the top is more than o.i cc. It is difficult to 

1 In order to take care of any excess of pressure in the generator, be sure to have 
stop-cock No. 2 open (see p. 277). 



294 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

formulate any rule for how much unabsorbed gas should be 
allowed, since the rate varies, etc., but if much gas collects, then 
the stop-cock (No. 7) should be opened again to let the solution 
flow down and carbon dioxide run through freely for another 
five minutes, and a second trial made for almost complete ab- 
sorption as before. If the gas is not passing too rapidly the bub- 
bles diminish to the size of pin-points as they float upward. If 
much unabsorbed gas is collected again either the cupric oxide 
has not been properly prepared or the generator and joints leak 
or the carbonate is impure, and these must be attended to. 
This operation shows the chief error involved in the determination 
of nitrogen and therefore the error in the final result will be in 
almost direct relation to the amount of gas unabsorbed in these 
blank tests. 

If there is any doubt as to the proper condition of the appara- 
tus a complete blank run should be carried out, using, for example, 
0.2 gram of sucrose (cane sugar) in place of a nitrogenous sub- 
stance. 

When the test is satisfactory let that part of the combustion 
tube which is to contain the boat, and several centimeters each 
side of it, cool down to room temperature. During the cooling 
reduce the rate of the carbon dioxide, or close stop-cocks Nos. 5 
and 6 to prevent any of the potassium hydroxide solution from 
being drawn into the combustion tube. If a combustion is not 
to be made immediately, let the entire tube cool down in an 
atmosphere of carbon dioxide (see p. 291). 

The Combustion. The following arrangements are made 
for beginning the combustion proper depending upon whether 
the furnace is cold or heated in part: 

a. 1 If the furnace is cold, disconnect both ends of the com- 
bustion tube, carefully remove the cupric oxide spiral, 
insert the boat containing the substance, 2 replace the cupric 

b. oxide spiral, and then insert the cold reduced copper spiral 

1 These letters in the margin refer to the corresponding parts in the Topical 
Outline, section u, p. 273. 

2 If the substance burns with difficulty it should be covered with some of the 
cupric oxide wire already prepared for this purpose (p. 290). 



ORGANIC COMBUSTIONS 295 

in the position reserved for it beyond the layer of cupric 

c. oxide. Connect up the apparatus again, remove the air 
by evacuation and flood with pure C(>2 by the usual proce- 

d. dure. While the reservoir of the azotometer is in position 
I and stop-cocks Nos. 6 and 7 are open, and carbon dioxide 
is slowly passing through the apparatus, heat the reduced 
copper spiral to redness in order to drive out any occluded 
gases, such as hydrogen and air, and then heat the adjacent 
cupric oxide, making certain that the substance in the 
boat is not heated at all. This can be done if the long 
heating section, No. 2, is pushed over toward the reduced 
spiral (see general diagram, p. 276). 

c. While the tube is thus being heated, test the apparatus 

to see if the amount of unabsorbed gas is at a minimum, as 

/. described at the beginning of this chapter. If the sub- 
stance decomposes readily the heating of the cupric oxide 
should be delayed until after the final test. 

If the combustion tube has been heated and only that part 
which is to contain the boat and several centimeters on each 
side of it including the cupric oxide spiral have been allowed 
to cool down practically to room temperature, then, in order 
to make the final preparations, disconnect both ends of the 
combustion tube, carefully remove the cupric oxide spiral, 

a insert the boat containing the substance, 1 and quickly 
replace the spiral. Connect up this end only, leaving 
the other end open, and pass CC>2 rapidly through the tube. 
When you are reasonably certain that the air has been 

b. driven out, insert the cold reduced copper spiral into the 

c. heated part of the tube and quickly connect the azotometer, 
making sure beforehand that stop-cocks Nos. 6 and 7 are 

d. open and the reservoir is in low position I. In this way 
the reduced spiral will not become oxidized, provided there 
is a good flow of C(>2. Any occluded gases in the reduced 
spiral will be driven out in about five minutes of strong 

e. heating. Now test the apparatus to see if the amount of 

1 As stated above, if the substance burns with difficulty it should be covered 
with some of the cupric oxide wire already prepared for this purpose (p. 290). 



296 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

unabsorbed gas is at a minimum, as described at the be- 
ginning of this chapter. 

/. It must be borne in mind that these preliminary opera- 

tions should be varied in accordance with the properties 
of the substance. If it has a high vapor pressure and sub- 
limes readily or is easily melted, the time factor must be 
reduced, the heating regulated, etc. Furthermore, it 
cannot be overemphasized that good judgment and familiar- 
ity with the method are always very necessary to give reliable 
results. 

As soon as it has been found that the amount of un- 
absorbed gas has been reduced to the proper minimum 
g. amount, reduce the flow of carbon dioxide to such an extent 
that it will just keep the products of combustion moving 
toward the azotometer, using the stopper (No. 5) in the 
U-tube for regulating the gas, and allowing the excess of 
carbon dioxide in the generator to escape regularly through 
stop-cock No. 2 and the safety bottle. 

Raise up the reservoir and when it is opposite the stop- 
cock (No. 7), open the stop-cock to allow the small amount of 
unabsorbed gas that may have collected to pass out, care- 
fully close the stop-cock, leaving some of the solution in the 
cup above, and lower the reservoir to position I. If there 
has been any indication that the substance has begun to 
decompose then the small amount of unabsorbed gas should 
not be driven out of the azotometer lest some nitrogen from 
the substance be driven out too. 

h. Now gradually heat more of the cupric oxide by drawing 

the long heating section (No. 2) toward the boat a centi- 
meter at a time, and at the same time begin to heat slowly 
the cupric oxide spiral on the other side of the boat with 
section No. i. 

As mentioned in connection with the carbon and hydro- 
gen determination (p. 254), it is very difficult to describe 
in detail the actual method of burning the substance, since 
each one has its own peculiarities, and therefore only a 



ORGANIC COMBUSTIONS 297 

general description can be given. Here also an idea as to 
how the substance behaves on heating should be gained 
beforehand, if sufficient is available, by heating it and 
gradually burning it in a boat over a small flame. Notice 
whether it gradually burns, sublimes, or suddenly decom- 
poses. 

The substance is slowly burned by gradually drawing 
the two adjacent sections closer and closer in alternate turns 
toward the boat. When the large heating section (No. 2) 
is over all the cupric oxide do not draw it any further. Use 
the small heating section (No. i) to heat and slowly and com- 
pletely decompose the substance in the boat. Since the 
substance chars and the carbon is not completely burned in 
the presence of carbon dioxide, the amount and appear- 
ance of the black deposit does not give a very good indica- 
tion of the course of the combustion. But the amount of 
gas which enters the azotometer, and, passing upward, is 
only partially absorbed, does give a good idea as to how the 
combustion is progressing. The gas should not come 
through so fast that the bubbles will be very large and 
rapidly fill the azotometer tube, since there is danger that 
all the potassium hydroxide solution will be driven over into 
the reservoir and then the gas will follow ! 

After about twenty minutes the substance will all be 
decomposed and the rate of the gas entering the azotometer 
will then decrease to that of the carbon dioxide itself. 

i. Now drive over the remaining nitrogen with carbon dioxide 
by gradually increasing the flow of the latter, and continue 
this until the bubbles of unabsorbed gas are very tiny just 
as was noticed before the combustion was begun. If the 
volume of nitrogen in the azotometer is large the bubbles 
will not have very much liquid through which to travel 
and on this account it is sometimes not so easy to make a 
proper comparison. In such a case the gas is run through 
for about ten minutes after it appears that all the nitrogen 
has been driven over. 

/. Then close stop-cock No. 6 (between the azotometer and 



298 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

the combustion tube), and wash the nitrogen in the azo- 
tometer with one portion of the potassium hydroxide solu- 
tion. This is done while the reservoir is in the low position 
(I), the stop-cock being carefully and partially opened to 
allow the solution to run easily down the inside walls to 
absorb any traces of carbon dioxide that may be present, 
and closed before all the solution has left the cup. Now 
wash the gas in a similar manner with successive portions 
of cold distilled water which has been recently boiled to 
drive out dissolved air, 1 until all the potassium hydroxide 
solution is out of the azotometer and the reservoir also. 
Always keep some liquid in the cup. While the washing is 
being done do not let the potassium hydroxide solution over- 
flow. It should be poured out and saved for a second 
combustion unless it is " spent," and when you pour it out 
be sure not to pour all of it at a time, since air may get 
into the rubber tube and then into the azotometer! 

k. Raise up the reservoir until the liquid in it is on a level 

with the liquid in the azotometer in order that the nitrogen 
will remain at atmospheric pressure, thus preventing any 
error from leakage, etc., and clamp the holder of the reser- 
voir in this position. Place a thermometer in some water in 
the cup above, or hang it beside the azotometer, and allow 
the apparatus to remain untouched in a room of uniform 
temperature for at least twenty to thirty minutes. Then 
record the volume of the gas, as read by the bottom of 
the meniscus, the temperature, and also the barometric 
reading and the temperature of the barometer. 

/. From these results and the weight of i cc. of moist 

nitrogen (given in milligrams) as found in the accompanying 
tables, for the proper temperature and pressure, you can 
calculate the weight of nitrogen obtained and then the per- 
centage of nitrogen in the substance (see section on Cal- 
culations, p. 300). 

1 Otherwise this air will be liberated when the water mixes with the potassium 
hydroxide solution which does not dissolve as much air as water does. 



ORGANIC COMBUSTIONS 299 

NOTES 

1. Some operators prefer to measure the nitrogen over the potas- 
sium hydroxide solution. The weight of the nitrogen is different 
from what it is when measured over water on account of the differ- 
ence in vapor pressure of the two liquids. One of the difficulties, 
however, in reading the volume over the alkaline solution is that it 
is practically impossible to get rid of the foam. 

2. If only a small amount of water is used for the washing, not 
enough to displace all the potassium hydroxide solution, the column 
of liquid in the reservoir and its connecting tube will be of a greater 
density than the water in the azotometer tube. This means that the 
volume of nitrogen will be somewhat compressed when the two 
columns are leveled for the reading. This error would of course 
aid in reducing the " normal" error which is always too much, but 
any known error in manipulation should not be tolerated. 

3. Some azotometers are made in such a way that water is 
retained at the top of the tube under the stop-cock. This changes the 
reading of the volume of nitrogen. By gently tapping the tube it 
can be made to run down the walls to the liquid below. Then allow 
it to stand, etc. 

In order to have the tube ready for another combustion, 
the cupric oxide which has been partially reduced must be 
reoxidized. Do not allow the cupric oxide to cool with air 
in the tube if another combustion is to be made. 1 Without 
allowing the furnace to cool, disconnect the azotometer, 
remove the reduced copper spiral from the end near the 
azotometer, and while the tube is continued to be heated to 
redness draw air through it for several minutes. Then 
without diminishing the heat remove the remaining air and 
flood the apparatus with carbon dioxide in the usual manner. 
Now it may be used again at once, or it can be closed off 
and the cupric oxide allowed to cool in the atmosphere of 
carbon dioxide (p. 291). 

1 If there is not time to re-oxidize the cupric oxide, be sure to let the tube 
cool with carbon dioxide in it. 



300 



LABORATORY MANUAL OF ORGANIC CHEMISTRY 



GENERAL NOTES 

1. Some substances give off gases, such as methane, which are 
not oxidized by the cupric oxide in the absence of oxygen gas. These 
must be mixed with coarsely powdered lead chromate or freshly 
precipitated cuprous chloride, and the long layer of cupric oxide 
replaced with lead chromate. 

2. In some cases the entire space occupied by the boat must be 
filled with cupric oxide mixed with the substance in order to get 
intimate contact. 

3. If any nitric oxide, NO, has escaped the action of the reduced 
copper spiral its presence can be shown by the brown fumes formed 
when the nitrogen gas is allowed to come out into the air. Nitrogen 
as nitric oxide occupies only half the volume of the same amount of 
nitrogen in the free state. 

VIII. Calculations, and Discussion of Results 

Having ascertained the volume of the nitrogen, V, its tem- 
perature, /, and the barometric reading and the temperature of 
the barometer (p. 298), correct the barometric reading to zero 
by using the following formula and table. 1 



where 



H Q = corrected reading ; 
h = observed reading; 
a = coefficient; 
t = temperature; 



h 


a 


/; 


a 


h 


a 


h 


a 


720 


.1170 


736 


.1196 


752 


.1221 


768 


.1248 


722 


1173 


738 


.1199 


754 


.1224 


770 


.1251' 


724 


.1176 


740 


.1202 


756 


.1228 


772 


.1254 


726 


.1180 


742 


.1205 


758 


.1231 


774 


1257 


728 


.1183 


744 


.1208 


760 


.1235 


776 


.1261 


730 


.1186 


746 


.1212 


762 


.1238 


778 


.1264 


732 


.1189 


748 


.1215 


764 


.1241 


780 


.1267 


734 


.1192 


750 


.1218 


766 


1245 







1 This table gives the correction for a brass scale. The correction is approx- 
imately 8 per cent greater for a glass scale. It is very convenient to place a 
copy of this table for ready reference in the case surrounding the barometer. 



ORGANIC COMBUSTIONS 301 

The weight of the nitrogen can now be found by the formula: 



Wt. in 



= o.ooi2 S o7X 



-, . . 
76 (273+0 

where 0.0012507 is the weight of i cc. of pure dry nitrogen at 
normal temperature and pressure; 

F = volume of nitrogen in cubic centimeters; 
HO = corrected barometric pressure; 

p = vapor pressure of water at t\ 

t = temperature. 

TABLE OF VAPOR PRESSURE OF WATER l 



/ 


mm. 


t 


mm. 


t 


mm. 


t 


mm. 





4-6 


9 


8 6 


18 


iS-S 


27 


26.7 


I 


4-9 


10 


9 2 


19 


16.5 


28 


28.4 


2 


5-3 


ii 


9.8 


20 


17-5 


29 


30 i 


3 


5-7 


12 


10-5 


21 


18,7 


30 


31-8 


4 


6.1 


13 


IT .2 


22 


19. 8 


3i 


33-7 


5 


6-5 


14 


12.0 


23 


21. 1 


32 


35-7 


6 


7.0 


IS 


12.8 


24 


22.4 


33 


37-7 


7 


7-5 


16 


13 6 


25 


23.8 


34 


39 9 


8 


8.0 


17 


14 5 


26 


25.2 


35 


42.2 



The weight of nitrogen can more readily be obtained by 
using the accompanying tables (page 303), which give the 
weight of i cc. of moist nitrogen at different temperatures and 
pressures. 

The percentage of nitrogen in the substance will be: 

T. . XT Wt. nitrogenXioo 

Per cent N = rf- . 

Wt. substance 

For logarithmic 2 calculation: 

1 From Scheel and Heuse, Ann. Physik., 31 (1910), 731, as given in the 
Smithsonian Physical Tables, Third Reprint of Sixth Revised Edition (1918), 

IS4-S- 

2 A table of four-place logarithms is given on p. 308. 



302 LABORATORY MANUAL OF ORGANIC CHEMISTRY 

A , , f Log. wt. i cc. N at / and // = 

Ada i T _ 

I Log. F = 



A , , [ Log. wt. total nitrogen 
Add \ 

( Log. 100 



Subtract ^ r 

Log. wt. substance 

Log. per cent N = 

The Limit of Error. This may be calculated in the same 
general way as given on p. 258. For results of analysis, obtained 
by the method described, the " allowed " error should ordinarily 
not be more than 10 parts per thousand, and never more than 20 
parts per thousand. Check results should also come within these 
figures. 

The following results are given as being typical of the possibili- 
ties in the method: ^-nitro- toluene (CyHyC^N) was analyzed 
for nitrogen by Mr. S. L. Handforth with the following results 
(only two analyses made): N = 10.29%, 10.30%; theory calls 
for N= 10.22%. The error here is 6.9 and 7.8 parts per thousand, 
respectively. The same substance was also analyzed by Miss 
Sophia Schulman, N = 10.09%, 10.23%, 10.18%; error, 12.7 
(low), 0.9 and 3.9 (low) parts per thousand; and also by Mr. 
H. R. Pyne, N = 10.15%, 10.36%; error, 6.8 (low), 13.7 parts per 
thousand. Mr. T. C. Taylor obtained for nitrogen in diphenyl- 
amine (Ci 2 HnN), N = 8.28%, 8.32%; theory, N = 8. 28%; one 
result is quite fortuitous, the error in the other is 4.8 parts 
per thousand. Mr. Geo. H. Walden obtained for acetanilide 
(C 8 H 9 ON); N = 10.32%, 10.43%; theory, N = 10.37%; error is 
4.8 (low), and 5.8 parts per thousand. The greatest differ- 
ence in the results in any of the sets of determinations men- 
tioned is 0.21 (Mr. Pyne), and the error, based on the lower 
figure, is 20.7 parts per thousand. 



WEIGHT OF ONE CUBIC CENTIMETER OF MOIST 303 
NITROGEN IN MILLIGRAMS* 



t 


6692 


694 


696 


698 


700 

_. 


702 


704 


706 


708 


710mm 


6 


1.108 


i. in 


i . n/j 


i 117 


I .121 


i 124 


1.127 


1.130 


I-I34 


i.i37 




04439 


04565 


04691 


04817 


, 04043 


05068 


05192 


05317 


05441 


05564 


6 


1.103 


1.106 


1.109 


1.113! 1.116 


i 119 


I 122 


1. 125 


1.129 


1.132 




04251 


04378 


04504 


04630] 04755 


04880 


05005 


05130 


05254 


05378 


7 


i 098 


I . IOI 


I . IOC 


1.108 


I . Ill 


1. 114 


I. 117 


I. 121 


1.124 


1.127 




04063 


04190 


04316 


04442 


04568 


04693 


04818 


04943 


05067 


05191 


8 


i 093 


i 097 


I . IOO 


I . IO v ' 


i 106 


i .109 


I.II3 


1.116 


I IIQ 


I. 122 




03877 


04003 


04130 


04256 


04382 


04507 


04632 


04757 


04881 


05005 


9 


1.089 


1.092 


1.095 


i . 098 


I IOI 


1.105 


i . 108 


i. in 


I.II4 


I.II7 




03691 


03818 


03944 


04070 


04196 


04322 


04447 


04571 


04696 


04820 


10 


1.084 


i 087 


1.090 


i .093 


1.097 


I . IOO 


i . 103 


i . 1 06 


I.I09 


I. II 3 




03499 


03626 


03752 


03879 


04005 


04130 


04255 


04380 


04505 


04629 


11 


1.079 


1.082 


1.085 


1.088 


i .092 


i 095 


1.098 


I . IOI 


I . IO4 


I.I07 




03300 


03427 


03554 


03680 


03806, 


03932 


04057 


04182 


04307 


04431 


12 


1.074 


1.077 


1.081 


1.084 


1.087 


i .090 


i 093 


i .096 


I 099 


I.I03 




03109 


03236 


03363 


03490 


03616) 


03741 


03867 


03992 


04II7 


04241 


13 


i .069 


1.073 


1.076 


1.079 


1.082] 


1.085 


1.088 


i .091 


1.095 


1.098 




02912 


03040 


03167 


03293 


03420 


03546 


03671 


03796 


03921 


04046 


14 


1.064 


1.068 


1.071 


1.074 


i 077j 


i. 080 


i 083 


1.086 


1.089 


1.093 




02709 


02837 


02964 


03091 


03217 


03343 


03469 


03594 


03719 


03844 


15 


1.059 


1.063 


1.066 


i .069 


i .072! 


1.075 


i 078 


1.081 


1.084 


1.088 




02507 


02635 


02762 


02889 


03016' 


03142 


03268 


03393 


03518 


03643 


16 


i 055 


1.058 


1.061 


1.064 


1.067 


1.070 


i . 073 


1.076 


1.079 


1.083 




02305 


02433 


02560 


02687 


02814' 


02940 


03066 


03192 


03317 


03442 


17 


i 050 


1-053 


1.056 


1.059 


1.062 


i . 065 


i 068 


1.071 


1.074 


1.077 




02097 


02225 


02353 


02480 


02607 


02734 


02860 


02985 


03III 


03236 


18 


i 045 


i .048 


1.051 


1-054 


1.057 


i . 060 


i 063 


i. 066 


1.069 


I.O72 




01890 


02018 


02146 


02273 


02400 


02527 


02653 


02779 


02905 


03030 


19 


1.039 


i .042 


i .046 


1.049 


1.052 


i 055 


1.058 


i 06 1 


1.064 


1.067 




01676 


01805 


01933 


02060 


02188 


02314 


02441 


02567 


02693 


028l8 


20 


1.034 


i 037 


1.040 


1.043 


1.046 


1.049 


1-053 


i .056 


1.059 


I .062 




oi457 


01585 


01713 


01841 


01969 


02096 


O2222 


02349 


02475 


02600 


21 


i .029 


1.032 


1-035 


i 038 


i .041 


1.044 


1.047 


1.050 


1-053 


1.056 




01238 


01367 


01495 


01623 


01751 


01878 


02005 


02131 


02257 


02383 


00 

A& 


1.024 


i 027 


i 030 


1-033 


1.036 


i 039 


1.042 


1.045 


1.048 


I 051 




01019 


01148 


01276 


01405 


01532 


01660 


01787 


01914 


02040 


O2I66 


23 


1.018 


I O2I 


1.024 


i 027 


i . 030 


i 034 


1.037 


1.040 


1-043 


I 046 




00788 


00917 


01046 


01174 


01302 


01430 


01557 


01684 


01811 


01937 


24 


i .013 


I .Ol6 


i 019 


i .022 


1.025! 


i O28j i 031 


i 034' i 037 


I 040 




00557 


00686 


00815 


00944 


01072 


OI2OO 


01328 


01455 01582 


01708 


25 


1.008 


I. Oil 


i 014 


i .017 


i .020 


1.023 


I 026 


i .029 


i 032 


1.035 




00326 


00456 


00585 


00714 


00843 


00971 


01099 


01226 


oi353 


01480 


26 


i .002 


1.005 


i 008 


I. Oil 


1.014 


I.OI7 


1.020 


1.023 


i 026 


1.029 




00083 


00213 


00342 


00472 


00600 


00729 


00857 


00985 


Oil 12 


01239 


27 


o 996 0.999 


i .002 


1.005 


i 008 


I. Oil 


I.OI4 


i .017 


I .O2O 


I .023 




99840! 99970 


OOIOO 


00230 


00359] 


00488 


OO6l6 


00744 


00872 


00999 


28 


0.991 o 994 


0.997 


I. 000 


i 0031 


1 .006 


I OO9 


I. 012 


I.OI5 


I.OI8 




99500 99721 


99851 


99981 


OOIIO 


OO22O 


00368 


00497 


OO625 


00752 


29 


o 985 o 988 


0.991 


0.994 


0.997 


I. 000 


1.003 


i .006 


I .OO9 


I .OI2 




99341 09472 


99603 


99733 


99863 


99994 


OOI2I 


00250 


00378 


00506 


30 


0.079 o 982 


0.985 


0.988 


o 99i 


0.994 


0.997 


I. 000 


1.003 


I OO6 




99079J 99211 


99341 


99472 


99602 


99732 


99861 


99990 


OOII9 


00247 


t 


b 692 694 


696 


698 


700 


702 


704 


706 


708 


710mm 



* From the Third American Edition of Gatterman's " Practical Methods of Organic 
Chemistry," published by The Macmillan Company, reprinted by permission. 



304 WEIGHT OF ONE CUBIC CENTIMETER OF MOIST 
NITROGEN IN MILLIGRAMS 



t 


6712 


714 


716 


718 


720 


722 


724 


726 


728 


730mm 


5 


1.140 


1.143 


1.146 


1.150 


1-153 


1.156 


I-I59 


1.163 


1.166 


i .169 




05688 


05811 


05933 


06055 


06177 


06299 


06420 


06541 


06662 


06782 


6 


i -i3S 


1.138 


1.142 


1.145 


1.148 


1.151 


i.i54 


1.158 


1.161 


i 164 




05501 


05624 


05747 


05869 


05991 


06113 


06234 


06355 


06476 


06596 


7 


1.130 


1-133 


1-137 


1.140 


1-143 


i 146 


1.149 


1-153 


1.156 


i i59 




053U 


05437 


05560 


05682 


05804 


05926 


06048 


06169 


06289 


06410 


8 


1.125 


i . 129 


1.132 


i i35 


1.138 


1.141 


1. 145 


1.148 


1.151 


I-I54 




05128 


05251 


05374 


05497 


05619 


05741 


05862 


05983 


06104 


06225 


9 


I. 121 


1.124 


1.127 


1.130 


1-133 


1-137 


i . 140 


1-143 


i .146 


1.149 




04Q43 


05067 


05190 


05312 


05434 


05556 


05678 


05796 


05920 


06041 


10 


i . 116 


i .119 


I. 122 


1.125 


1.128 


1.132 


1. 135 


1.138 


i .141 


1.144 




04752 


04876 


04999 


05121 


05244 


05366 


05488 


05609 


05730 


05851 


11 


i .in 


i . 114 


1.117 


I 120 


1.123 


1.126 


i 130 


i-i33 


i . 136 


I-I39 




04555 


04679 


04802 


04925 


05047 


05169 


05291 


05412 


05534 


05654 


12 


i 106 


1. 109 


I. 112 


1 H5 


1.118 


I. 122 


i. US 


1.128 


1.131 


I-I34 




04365 


04489 


04612 


04735 


04857 


04980 


05101 


05223 


05344 


05465 


13 


I .IOI 


i 104 


I.I07 


I.IIO 


1.113 


I.II7 


I. I 20 


1.123 


1.126 


i 129 




04170 


04293 


04417 


04540 


04662 


04785 


04907 


05029 


05150 


05271 


14 


1.096 


1.099 


I . IO2 


1 . 105 


1.108 


i. in 


I . 114 


1.118 


I. 121 


1.124 




03968 


04092 


04215 


04339 


04461 


04584 


04706 


04828 


04949 


05070 


15 


1.091 


1.094 


1.097 


I. 100 


1.103 


i 106 


I.I09 


1.113 


i 116 


i 119 




03767 


03891 


04015 


04138 


04261 


04384 


04506 


04628 


04750 


04871 


16 


i. 086 


1.089 


I .092 


1.095 


i.o 9 s! 


I IOI 


I IO4 


i . 107 


i. in 


1.114 




03567 


03691 


03815 


03938 


04061 ' 04184 


04306 


04428 


04550 


04672 


17 


1.081 


1.084 


I 087 


1 .090 


I.OQ} 


i og6 


I 099 


I. IO2 


i 105 


1.108 




03361 


03485 


03609 


03733 


03836 


03979 


04101 


04224 


04345 


04467 


18 


1-075 


1.078 


1.082 


1.085 


1.088 


I OQJ 


I OQ4 


I 097 


I 100 


1.103 




03155 


03279 


03403 


03527 


03650 


03774 


038Q6 


0401 Q 


04141 


04262 


19 


i .070 


i 073 


1.076 


1.079 


1.082 


I 086 


1.089 


I 092 


I 095 


1.098 




02943 


03068 


03192 


03316 


03440 


03563 


03686 


03808 


03931 


04053 


20 


1.065 


1.068 


I.07I 


1.074 


1.077 


1.080 


1.083 


I. 086 


1.089 


i .092 




02725 


02850 


02975 


03099 


03223 


03346 


03469 


03592 


03715 


03837 


21 


i .060 


1.063 


1.066 


1.069 


1.072 


1-075 


1.078 


i 081 


1.084 


1.087 




02509 


02634 


02758 


02883 


03007 


03130 


03254 


03377 


03499 


03621 


22 


1.054 


1-057 


I. 060 


I 063 


1.066 


1.069 


i . 073 


i . 076 


1.079 


i 082 




02292 


02417 


02542 


02666 


02791 


02914 


03038 


03161 


03284 


03406 


23 


1.049 


1.052 


1-055 


1.058 


i 061 


1 .064 


1.067 


1.070 


1.073 


1.076 




02063 


02189 


02314 


02439 


02563 


02087 


02811 


02934 


03057 


03180 


24 


1.043 


i .046 


1.049 


1 .052 


1-055 


1.058 


i .061 


i .064 


1.067 


1.070 




01834 


01960 


02085 


02210 


02335 


02459 


02583 


02707 


02830 


02953 


26 


1.038 


1.041 


1.044 


1.047 


1.050 


I 053 


i 056 


i 059 


I 062 


i 065 




01606 


01732 


01858 


01983 


02108 


02233 


02357 


02481 


02604 


02727 


26 


1.032 


i 035 


1.038 


I .041 


i 044 


1.047 


i 050 


T-053 


1.056 


1-059 




01366 


01492 


Ol6l8 


01743 


01868 


01993 


02ii8| 02242 


02366 


02489 


27 


1.026 


i 029 


1.032 


I 035 


1.038 


1.041 


1.044 1.047 


1.050 


1.053 




01126 


01252 


01378 


01504 


01630 


01755 


01879 


02004 


02128 


02251 


28 


i .020 


1.023 


I .026 


I .029 


1.032 


1-035 


1.038 


i .041 


1.044 


1.047 




00879 


01006 


OH33 


OI25Q 


01384 


01510 


01635 


o 759 


01884 


02008 


29 


1.015 


1.018 


I .O2I 


I 024 


i .027 


I 030 


1.033 


i 036 


1.039 


1.042 




00634 


00761 


00887 


OIOI4 


01140 


01265 


01391 


01516 


01640 


01764 


30 


1.009 


I. 01 2 


I.OI5 


I.OI8 


i .021 


1.024 


1.027 


i .029 


1.032 


1.035 




00375 


00502 


00629 


00756 


00882 


01008 


01134 


01259 


01384 


01509 


t 


6712 


714 


716 


718 


720 


722 


724 


726 


728 


730mm 



WEIGHT OF ONE CUBIC CENTIMETER OF MOIST 3Q5 
NITROGEN IN MILLIGRAMS 



t 


6732 


734 


736 


738 


740 


742 


744 


746 


748 


750mm 


6 


1.172 


1.176 


1.179 


1.182 


r . 185 


i 188 


i . 192 


i . i95 


1.198 


I. 201 




06902 


07021 


07141 


07259 


07378 


07496 


07614 


07732 


07849 


07966 


6 


i .167 


1.170 


1.174 


1.177 


1.180 


1.183 


1.187 


1.190 


1-193 


I.I96 




06716 


06835 


06955 


07074 


07192 


07311 


07429 


07546 


07664 


07781 


7 


1.162 


1.166 


1.169 


1.172 


I.I75 


1.178 


1.182 


1.185 


1.188 


I.I9I 




06530 


06650 


06769 


06888 


07007 


07125 


07243 


07361 


07479 


07596 


8 


1-157 


1.161 


i . 164 


i 167 


1.170 


1. 173 


1.177 


1.180 


1.183 


I.I86 




06345 


06465 


06584 


06703 


06822 


06941 


07059 


07177 


07294 


074II 


9 


i 152 


1.156 


1-159 


1.162 


1.165 


1.168 


1.172 


1-175 


1.178 


1.181 




06161 


06281 


06400 


06520 


06638 


06757 


06875 


06993 


07111 


07228 


10 


1.147 


1.151 


i.i54 


i.i57 


I 160 


i . 163 


1.166 


i 170 


1-173 


1.176 




05971 


06091 


06210 


06330 


06449 


06567 


06686 


06804 


06922 


07039 


11 


i 142 


I-I45 


1.149 


i 152 


I-I55 


1.158 


i 161 


i 164 


1.168 


1.171 




05775 


05895 


06015 


06134 


06253 


06372 


06490 


06609 


06726 


06844 


12 


1-137 


1.140 


1.144 


1.147 


1.150 


I.I53 


i 156 


i 159 


1.163 


1.166 




05586 


05706 


05826 


05945 


06064 


06183 


06302 


06420 


06538 


06656 


13 


1.132 


i.i35 


i i39 


1. 142 


I-I45 


i 14^ 


1.151 


I.I54 


1. 157 


i 161 




05392 


05512 


05632 


0575J 


05871 


05990 


06108 


06227 


06345 


06463 


14 


1.127 


1.130 


i-i33 


1.136 


i 140 


1 T 43 


1.146 


119 


1.152 


i.iSS 




05191 


05312 


05432 


05552 


05671 


OS7QO 


05909 


06028 


06146 


06264 


15 


I 122 


1.125 


1.128 


1.131 


I-I34 


I.I37 


i 141 


1.144 


1.147 


1.150 




04992 


05113 


05233 


05353 


05472 


05592 


05711 


05829 


05947 


06065 


16 


I.II7 


i .120 


1.123 


1. 126 


i .129 


1.132 


i 135 


1.138 


1.142 


1. 145 




04793 


04913 


05034 


05154 


05274 


05393 


05512 


05631 


05749 


05867 


17 


I III 


1.115 


1.118 


I . 121 


i 124 


i 127 


i 130 


I-I33 


1.136 


1. 139 




04588 


04709 


04830 


04950 


05070 


05189 


05308 


05427 


05546 


05664 


18 


1.106 


i .109 


I . 112 


i 116 


I .119 


I 122 


i 125 


i 128 


1.131 


I-I34 




04384 


04505 


04625 


04746 


04866 


04986 


05105 


05224 


05343 


05461 


19 


I.IOI 


1.104 


I . IO7 


I IIO 


i 113 


I Il6 


I . 1IQ 


I .122 


i .126 


i .129 




04174 


04295 


04416 


04537 


04657 


04777 


04896 


05015 


05134 


05253 


20 


1-095 


1.099 


I. 102 


I 105 


i .108 


I III 


I 114 


I.I17 


1. 1 20 


1.123 




03958 


04080 


04201 


04321 


04442 


04562 


04682 


04801 


O4920 


05039 


21 


1.090 


1.093 


I .096 


1.099 


I . IO2 


I IO5 


I IO$ 


I .III 


I.II5 


1.118 




03743 


03865 


03986 


04107 


04228 


04348 


04468 


04587 


04707 


04825 


22 


1.085 


i 088 


I O9I 


1.094 


1.097 


I 100 


I .103 


i 106 


I.I09 


1. 112 




03528 


03650 


03772 


03893 


04013 


04134 


04254 


04374 


04493 


04612 


23 


1.079 


1.082 


1.085 


i.o 8 


I 091 


I 094 


1.097 


I. 100 


I.I03 


1.106 




03302 


03424 


03546 


03667 


03788 


03909 


04029 


04149 


04268 


04388 


24 


1.073 


i 076 


I.OSO 


1-083 


I . 086 


I 089 


i 092 


1 .095 


I 098 


I . IOI 




03076 


03198 


03320 


03441 


03562 


03683 


03804 


03924 


04044 


04163 


25 


1.068 


1.071 


1.074 


i 077 


I 080 


1.083 


i. 086 


1.089 


I 092 


1.095 




02850 


02972 


03094 


03216 


03338 


03459 


03579 


03700 


03820 


03940 


26 


1.062 


1.065 


1.068 


i .071 


I 074 


1.077 


1.080 


1.083 


1.086 


1.089 




02612 


02735 


02857 


02979 


03IOI 


03222 


03343 


03464 


03584 


03704 


27 


I 056 


1-059 


I .062 


1.065 


I 068 


1.071 


1.074 


I 077 


1. 080 


I 083 




02375 


02498 


O262O 


02742 


02864 


02986 


03107 


03228 


03349 


03469 


28 


1.050 


1.053 


1.056 


1.059 


1.062 


1.065 


1.068 


1.071 


1.074 


1.077 




02131 


02254 


02377 


02500 


O2622 


02744 


02865 


02986 


03107 


03228 


29 


1.044 


1.047 


1.050 


i 053 


I 056 


1.059 


1.062 


1.065 


1.068 


1.071 




01888 


O2OI2 


02135 


02258 


02380 


02502 


02624 


02745 


02867 


02987 


30 


1.038 


I.04I 


1.044 


1.047 


1.050 


I 053 


1.056 


1.059 


1.062 


1.065 




01633 


01757 


01880 


02003 


O2I26 


02248 


02370 


02492 


026l4 


02735 


t 


67.32 


734 


736 


738 


740 


742 


744 


746 


748 


750mm 



306 



WEIGHT OF ONE CUBIC CENTIMETER OF MOIST 
NITROGEN IN MILLIGRAMS 



t 


6752 


754 


756 


758 


760 


762 


764 


766 


768 


770mm 


6 


1.205 


i 208 


I 211 


1.214 


i 218 


I. 221 


1.224 


i 227 


i 230 


1-234 




08083 


08199 


08315 


08431 


08546 


08661 


08776 


08891 


09005 


09119 


6 


i.iQQ 


i 203 


I 206 


i. 209 


1 212 


I 2l6 


1.219 


I 222 


1.225 


1.228 




07898 


08014 


08130 


08246 


08361 


08477 


08592 


08706 


08820 


08934 


7 


1.194 


1.198 


I . 2OI 


i 204 


I 2O7 


I .2IO 


i .214 


I.2I7 


i. 220 


1.223 




07712 


07829 


07945 


08061 


08177 


08292 


08407 


08522 


08636 


08750 


8 


1.189 


I-I93 


I .196 


1.199 


1.202 


1.205 


1.208 


I 212 


i 215 


i. 218 




07528 


07645 


07761 


07877 


07993 


08108 


08223 


08338 


08452 


08566 


9 


1.184 


1.188 


I 191 


1.194 


I. 197 


I 200 


1.203 


1.207 


i .210 


i 213 




07345 


07462 


07578 


07694 


078lO 


07925 


08040 


08155 


08270 


08384 


10 


1.179 


1.182 


I.I86 


1.189 


I.I92 


I 195 


1.198 


1.201 


i 205 


1.208 




07156 


07273 


07389 


07505 


07621 


07737 


07852 


07967 


08081 


08196 


11 


i 174 i 177 


1.180 


1.183 


I.I87 


i . 190 


i.i93 


I.I96 


i . 109 


i .202 




o()C)6i 


07078 


07195 


07311 


07427 


07542 


07658 


07773 


07887 


08002 


12 


i 1 60 


i 172 


i 175 


1.178 


1.181 


1.185 


1.188 


I.I9I 


I.IQ4 


1. 197 




06773 


06890 


07007 


07123 


07239 


07355 


07470 


07585 


07700 


07814 


13 


i 164 


i 167 


i 170 


i i73 


I 176 


i 179 


i 182 


i 186 


I 189 


i 192 




06580 


06697 


06814 


06930 


07046 


07162 


07278 


07303 


07508 


07622 


14 


1.158 


i 161 


i 165 


i 168 


I 171 


1.174 


1.177 


1.180 


1 . 183 


1.187 




06381 


06498 


06615 


06732 


06848 


06964 


07080 


07195 


07310 


07425 


15 


I.IS3 


i 156 


i 159 


i 162 


i 1 66 


i 169 


i 172 


i 175 


1.178 


1.181 




06183 


06300 


06417 


06534 


06650 


06767 


06882 


06998 


07113 


07228 


16 


1.148 


i 151 


i 154 


i.i57 


i 1 60 


i 163 


i . 166 


1.170 


I 173 


1.176 




05985 


06103 


06220 


06336 


06453 


06569 


06685 


06801 


06916 


07031 


17 


i .142 


i .146 


1. 149 


i 152 


i 155 


1.158 


1.161 


i . 164 


I 167 


1.170 




05782 


05900 


06017 


06134 


06251 


06367 


06483 


06590 


06714 


06829 


18 


I-I37 


1.140 


i T43 


1.146 


i I4Q 


i 153 


1.156 


i 159 


1.162 


i 165 




05579 


05697 


015814 


05931 


06048 


06165 


06281 


06397 


06512 


06627 


19 


1.132 


i -135 


1*138 


i .141 


1. 144 


1.147 


1.150 


I.I53 


1.156 


1. 159 




05371 


05489 


05607 


05724 


05841 


05957 


06074 


06190 


06305 


06421 


20 


i .126 


i 129 


1.132 


1.135 


1.138 


i . 141 


I-I45 


1.148 


1.151 


i.i54 




05157 


05275 


05393 


05510 


05627 


05744 


05861 


05977 


06093 


06208 


21 


I . 121 


i 124 


1.127 


1.130 


I.I33 


i . 136 


1.130 


i 142 


1.145 


1.148 




04944 


05062 


05180 


05298 


05415 


05532 


05649 


05765 


05881 


05997 


22 


I.II5 


1.118 


I . 121 


i 124 


1.127 


i 130 


I-I33 


i . 136 


1.139 


1.143 




04731 


04849 


04967 


05085 


05203 


05320 


05437 


05553 


05669 


05785 


23 


I.T09 


I. 112 


I.II5 


i . 119 


I. 122 


i 125 


! 128 


1.131 


1.134 


1. 137 




04507 


04625 


04744 


04862 


04979 


05097 


05214 


05330 


05447 


05563 


24 


1 . 104 


I.I07 


I HO 


i 113 


1.116 


i 119 


I 122 


1.125 


1.128 


1-131 




04282 


O44OI 


04520 


04638 


04756 


04873 


04991 


05108 


05224 


05341 


25 


1.098 


I .IOI 


1 .104 


i .107 


I .110 


1.113 


I.1I6 


i . 119 


I. 122 


1.125 




04059 


04178 


04297 


04415 


04533 


04651 


04769 


04886 


05002 


05119 


26 


1.092 


1-095 


I 098 


I .101 


1 .104 


1 .107 


I.IIO 


1.113 


1.116 


1.119 




03823 


03943 


04062 


04180 


04299 


04417 


04534 


04652 


04769 


04886 


27 


1. 086 


1. 080 


1.092 


1-095 


1.098 


I. IOI 


I.I04 


1.107 


I.IIO 


1.113 




03589 


03708 


03828 


03946 


04065 


04183 


04301 


04419 


04536 


04653 


28 


1.080 


I 08^ 


1.086 


1.089 


1 .092 


1 .095 


I .098 


I . 101 


1.104 


1.107 




03348 


03468 


03587 


03706 


03825 


03944 


04062 


04180 


04297 


04415 


29 


1.074 


1.077 


1.080 


1.083 


1.086 


1.089 


1.092 


1 .095 


1.098 


I. IOI 




03108 


03228 


03348 


03467 


03586 


03705 


03823 


03941 


04059 


04177 


30 


1.068 


I.O7I 


1.074 


1.077 


I 080 


1.083 


1. 086 


1.089 


1.092 


1.095 




02855 


02976 


03096 


03216 


03335 


03454 


03573 


03691 


03809 


03927 


t 


6752 


754 


756 


758 


760 


762 


764 


766 


768 


770mm 



WEIGHT OF ONE CUBIC CENTIMETER OF MOIST 307 
NITROGEN IN MILLIGRAMS 



t 


b 772 


774 


776 


778 


780mm 


5 


1.237 


i 240 


i 243 


1.247 


1.250 




09233 


09346 


09459 


09572 


09684 


6 


i . 232 


i - 235 


i . 238 


i . 241 


i 245 




09048 


09162 


09275 


09387 


09500 


7 


i . 226 


i . 230 


i 233 


1.236 


i . 239 




08864 


08977 


09090 


09203 


09316 


8 


I. 221 


i .224 


1.228 


1.231 


1-234 




08680 


08794 


08907 


09020 


09133 


9 


I 2l6 


i . 219 


I 223 


i 226 


i 229 




08498 


08612 


08725 


08838 


08951 


10 


I. 211 


i 214 


I.2I7 


I . 220 


i 224 




08310 


08423 


08537 


08650 


08763 


11 


I. 206 


i . 209 


I 212 


I 215 


i 218 




O8ll6 


08230 


08343 


08456 


08569 


12 


T . 2OO 


i . 203 


I 207 


I 210 


i 213 




07929 


08043 


08156 


08269 


08383 


13 


I 195 


i 198 


I 2OI 


I . 204 


i 208 




07737 


07851 


07964 


08078 


08191 


14 


I I9O 


i 193 


I .196 


I. 199 


1 202 




07539 


07653 


07767 


07881 


07994 


15 


I.I84 


i 187 


i . igo 


I 194 


I.I97 




07342 


07457 


07571 


07684 


07798 


16 


I 179 


T .182 


1.185 


i 188 


I 191 




07146 


07260 


07374 


07488 


07601 


17 


I- 173 


I 177 


1. 180 


i . 183 


i 186 




06944 


07058 


07173 


07287 


07400 


18 


I.I68 


I 171 


i 174 


1. 177 


i 180 




06742 


06857 


06971 


0708 T; 


07T99 


19 


I.l62 


i 166 


i 169 


T T72 


i 175 




06536 


06651 


06765 


06879 


06993 


20 


I.IS7 


i 160 


I 163 


1.166 


i 169 




06324 


06439 


06553 


06668 


06782 


21 


I.ISI 


I.I54 


I-I57 


1.160 


i . 163 




O6ll2 


06227 


06342 


06457 


06571 


22 


I . 146 


1.149 


1-152 


I.I55 


1.158 




05901 


06016 


06131 


06246 


06360 


23 


I . I4O 


i - 143 


1 . 146 


i 149 


1-152 




05679 


05791 


05909 


06024 


06139 


24 


I-I34 


I-I37 


1 . 140 


i 143 


i .146 




05457 


05572 


05688 


05803 


05917 


25 


I 128 


1.131 


I-I34 


I-I37 


i 140 




05235 


05351 


05467 


05582 


05697 


26 


I . 122 


1.125 


1.128 


1.131 


i . 134 




05002 


05118 


05234 


05349 


05465 


27 


i . 116 


i .119 


I 122 


i 125 


1.128 




04770 


04886 


05002 


05118 


05233 


28 


I .110 


i H3 


I . Il6 


i 119 


T . 122 




04531 


04648 


04764 


04880 


04996 


29 


i . 104 


1 .107 


I . IIO 


1.113 


I .Il6 




04294 


04411 


04527 


04644 


04759 


30 


1.098 


I . IOI 


1 . 104 


i 107 


I . IIO 




04045 


04162 


04278 


04395 


045II 


t 


6772 


774 


776 


778 


780mm 



308 



LOGARITHMS 



Natural 
Numbers 





1 


2 


3 


4 


5 


6 


7 


8 


9 


PROPORTIONAL PARTS. 


1 


2 


3 


4 


5 6 


7 


8 


9 


IO 


oooo 


0043 


0086 


0128 


0170 


0212 


0253 


0294 


0334 


0374 


4 


8 


12 


17 


21 25 


2Q 


33 


37 


II 


0414 


0453 


0492 


0531 


0569 


OOO7 


0645 


0682 


0719 


0755 


4 


8 


II 


IS 


19 23 


26 


30 


34 


12 


0792 


0828 


0864 0899 


0934 


096Q 


100^ 


1038 


1072 


1106 


3 


7 


IG 





17 21 


24 


28 


31 


13 


1139 


H73 


1 206 1 239 


1271 


J 303 


1335 


1367 


1399 


143 


3 


6 


1C 


s 


16 ig 


23 


26 


29 


14 


1461 


1492 


1523 


1553 


1584 


1614 


1644 


1673 


1703 


1732 


3 


6 





2 


15 18 


21 


24 


27 


IS 


1761 


1790 


1818 


1847 


1875 


1903 


i93i 


1959 


1987 


2014 


3 


6 


8 




14 17 


20 


22 


as 


16 


2041 


2068 


2095 


2122 


214* 


2175 


22OI 


2227 


2253 


2279 


3 


5 


8 




13 6 


18 


21 


24 


17 


2304 


2330 


2355 


2380 


2405 


2430 


2455 


2480 


2504 


2529 


2 


S 








7 


20 


22 


18 


2553 


2577 


2601 


2625 


2648 


2672 


2695 


2718 


2742 


2765 


2 


s 








6 


19 


21 


19 


2788 


2810 


2833 


2856 


2878 


2900 


292^ 


2945 


2967 


2989 


2 


4 








6 


18 


2O 


20 


3010 


3032 


3054 


3075 


3096 


3118 


3139 


3160 


3181 


3201 


2 


L 








s 


17 


19 


21 


3222 


3243 


3263 


3284 


3304 


3324 


3345 


3365 


3385 


3404 


2 


L 








4 


16 


18 


22 


3424 


3444 


34^4 


3483 


3502 


3522 


354i 


356o 


3579 


3508 


2 


4 








4 


IS 


17 


23 


3617 


3636 


3f>SS 


3674 


3692 


37ii 


3729 


3747 


3766 


3784 


2 


4 








; 


IS 


17 


24 


3802 


3820 


3838 


3856 


3874 


3892 


3909 


3927 


3945 


3962 


2 


t 








2 


14 


16 


25 


3979 


3997 


4014 


4031 


4048 


4065 


4082 


4099 


4116 


4133 


2 


3 






9 o 


12 


14 


IS 


26 


4150 


4166 


4183 


4200 


42l() 


4232 


4249 


4265 


4281 


4298 


2 


2 






8 o 


II 


13 


IS 


27 


4314 


4330 


4346 


4362 


4378 


4393 


440Q 


4425 


4440 


445 f 


2 


2 






8 9 


II 


13 


14 


28 


4472 


4487 


4502 


4518 


45.53 


4548 


45^4 


4579 


45<)4 


4(;oq 


2 


2 






8 9 


II 


12 


14 


2Q 


4624 


4f>39 


4<>54 


4669 


4683 


4698 


4713 


4728 


4742 


4757 


1 


3 


4 




1 ( 


ZO 


12 


13 


30 


477i 


4786 


4800 


4814 


4829 


4843 


4857 


4871 


4886 


4900 


I 


3 


4 




7 9 


10 


II 


13 


31 


4QI4 


4928 


4942 


4Q55 


4969 


4983 4997 


5011 


5024 


5038 


I 


3 


4 


6 


7 8 


10 


II 


12 


32 


5051 


5065 


5079 


5092 


5105 


5HQI5I32 


5M5 


5T59 


5^72 


I 


3 


4 


5 


7 8 


9 


II 


12 


33 


i85 


5198 


5211 


5224 


5237 


5250(5263 


5270 


5289 


5302 


I 


3 


4 


s 


6 8 


9 


10 


12 


34 


315 


5328 


5340 


5353 


5366 


5378 


5391 


5403 


54i6 


5428 


I 


3 


4 


s 


6 8 


9 


10 


II 


35 


441 


5453 


5465 


5478 


54QO 


5502 


55U 


5527 


S53Q 


555 r 


I 


2 


4 


s 


6 7 


9 


10 


II 


36 


563 


5575 


5587 


5599 


5611 


5^23 


5635 


5647 


S658 


5670 


1 


2 


i 


i 


6 7 


8 


10 


II 


37 


682 


5694 


57055717 


5729 


5740 


5752 


5763 


5775 


57^6 


I 


2 


3 


c 


6 7 


8 


9 


IO 


38 


798 


5809 


5821 


5832 


5843 


5855 


5866 


5877 


5888 


5899 


I 


2 


3 


s 


6 7 


8 


9 


10 


39 


QII 


5922 


5933 


5944 


5955 


5966 


5977 


$988 


5999 


ftoio 


I 


2 


3 


4 


5 1 


8 


9 


10 


40 


O2 1 


6031 


6042 


6053 


6064 


6075 


6085 


6og6 


6107 


6117 


I 


2 




^ 


5 6 


8 


9 


IO 


4i 


128 


6138 


6149 


6160 


6170 


6180 


6191 


6201 


f)2I2 


6222 


I 


2 


2 


/ 


S 6 


7 


8 


9 


42 


232 


6243 


6253 


6263 


6274 


6284 


6294 


6304 


>3I4 


6325 


I 


2 


2 


i 


S 6 


7 


8 


9 


43 


335 


6345 


6355 


6365 


6375 


6385 


6395 


6405 


6415 


6425 


I 


2 


2 


4 


5 6 


7 


8 


9 


44 


435 


6444 


H54 


6464 


6474 


6484 


6493 


6503 


6513 


6522 


I 


2 


3 


4 


S 6 


7 


g 


i) 


45 


532 


6542 


551 


6561 


6571 


6580 


6500 


6599 


6609 


6618 


! 


2 


3 


4 


5 6 


7 


8 


9 


46 


628 


6637 


646 


6656 


6665 


6675 


6684 


6693 


6702 


6712 


I 


2 


3 


4 


S 6 


7 


7 


8 


47 


721 


6730 


739 


6749 


6758 


6767 


6776 


6785 


>794 


6803 


I 


2 


3 


4 


5 5 


6 


7 


8 


48 


812 


6821 


6830 


6839 


6848 


6857 


6866 


6875 


6884 


6893 


I 


2 


3 


4 


4 S 


6 


7 


8 


49 


902 


6911 


6920 


6928 


6937 


6946 


6955 


6964 


6972 


6981 




2 


3 


4 


4 S 


6 


7 


8 


50 


990 


6998 


007 


7016 


7024 


7033 


7042 


7050 


7059 


7067 




2 


3 


3 


4 5 


6 


7 


8 


51 


076 


7084 


093 


7101 


7110 


7118 


7126 


7135 


7143 


7152 




2 


3 


3 


4 5 


6 


7 


V. 


52 


160 


7168 


177 


7i85 


7193 


7202 


7210 


7218 


226 


7235 




2 


2 


3 


4 5 


6- 


7 


7 


53 


243 


7251 


259 


7267 


7275 


7284 


7292 


300 


308 


7316 




2 


2 


3 


4 5 


o| 6 


7 


54 


324 


7332 


340 


7348 


735<3 


7364 


7372 


380 


388 


7396 




2 


2 


3 


4 d 


6 


6 


7 



LOGARITHMS 



309 



Natural 
Numbers. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


PROPORTIONAL PARTS. 


1 


2 


3 


4 


5 


6 


7 


8 





55 


7404 


7412 


74i9 


7427 


7435 


7443 


745i 


7459 


7466 


7474 


i 


2 


2 


3 


4 


5 


S 


6 


7 


56 


7482 


7490 


7497 


7505 


7513 


7520 


7528 


7536 


7543 


755i 


i 


2 


2 


3 


4 


5 


5 


6 


7 


57 


7559 


7566 


7574 


7582 


7589 


7597 


7604 


7612 


7619 


7627 


z 


2 


2 


3 


4 


5 


S 


6 


7 


58 


7634 


7642 


7649 


7657 


7664 


7672 


7679 


7686 


7694 


7701 


i 


I 


2 


3 


4 


4 


S 


6 


7 


59 


7709 


7716 


7723 


773i 


7738 


7745 


7752 


7760 


7767 


7774 


i 


I 


2 


3 


4 


4 


S 


6 


7 


60 


7782 


7789 


779<5 


7803 


7810 


7818 


7825 


7832 


7839 


7846 


i 


I 


2 


3 


4 


4 


S 


6 


6 


61 


7853 


7860 


7868 


7875 


7882 


7889 


7896 


7903 


7910 


7917 


i 


I 


2 


3 


4 


4 


5 


6 


6 


62 


7924 


7931 


7938 


7945 


7952 


7959 


7966 


7973 


798o 


7987 


i 


I 


2 


3 


3 


4 


5 


6 


6 


63 


7993 


8000 


8007 


8014 


8021 


8028 


8035 


8041 


8048 


8055 


i 


I 


2 


3 


3 


4 


S 


5 


6 


64 


8062 


8069 


8075 


8082 


8089 


8096 


8102 


8109 


8116 


8122 


i 


I 


2 


3 


3 


4 


5 


S 


6 


65 


8129 


8136 


8142 


8149 


8156 


8162 


8169 


8176 


8182 


8189 


i 


Z 


2 


3 


3 


4 


S 


S 


6 


66 


8i95 


8202 


8209 


8215 


8222 


8228 


8235 


8241 


8248 


8254 


i 


I 


2 


3 


3 


4 


5 


5 


6 


67 


8261 


8267 


8274 


8280 


8287 


8293 


8299 


8306 


8312 


8319 


i 


z 


2 


3 


3 


4 


5 


S 


6 


68 


8325 


8331 


8338 


8344 


8351 


8357 


8363 


8370 


8376 


8382 


i 


I 


2 


3 


3 


4 


4 


S 


6 


69 


8388 


8395 


8401 


8407 


8414 


8420 


8426 


8432 


8439 


8445 


i 


I 


2 


2 


3 


4 


4 


S 


6 


70 


8451 


8457 


8463 


8470 


8476 


8482 


8488 


8494 


8500 


8506 


i 


I 


2 


2 


3 


4 


4 


5 


6 


7i 


8513 


8519 


8525 


8531 


8537 


8543 


8549 


8555 


8561 


8567 


i 


I 


2 


2 


3 


4 


4 


5 


5 


72 


8573 


8579 


8585 


8591 


8597 


8603 


8609 


8615 


8621 


8627 


z 


z 


2 


2 


3 


4 


4 


5 


5 


73 


8633 


8639 


8645 


8651 


8657 


8663 


8669 


8675 


8681 


8686 


i 


z 


2 


2 


3 


4 


4 


S 


S 


74 


8692 


8698 


8704 


8710 


8716 


8722 


8727 


8733 


8739 


8745 


i 


z 


2 


2 


3 


4 


4 


S 


5 


75 


875i 


8756 


8762 


8768 


8774 


8779 


8785 


8791 


8797 


8802 


i 


z 


2 


2 


3 


3 


4 


5 


S 


76 


8808 


8814 


8820 


8825 


8831 


8837 


8842 


8848 


8854 


88 5Q 


i 


z 


2 


2 


3 


3 


4 


S 


5 


77 


8865 


8871 


8876 


8882 


8887 


8893 


8899 


8904 


8910 


8915 


i 


z 


2 


2 


3 


3 


4 


4 


S 


78 


8921 


8927 


8932 


8938 


8943 


8949 


8954 


8960 


8965 


8971 


r 


z 


2 


2 


3 


3 


4 


4 


5 


79 


8976 


8982 


8987 


8093 


8998 


9004 


9009 


9015 


9020 


9025 


i 


z 


2 


2 


3 


3 


4 


4 


5 


80 


9031 


9036 


9042 


9047 


9053 


9058 


9063 


9069 


9074 


9079 


i 


z 


2 


2 


3 


3 


4 


4 


5 


81 


9085 


9090 


9096 


9101 


9106 


9112 


9117 


9122 


9128 


9133 


i 


z 


2 


2 


3 


3 


4 


4 


5 


82 


9138 


9M3 


9149 


9154 


9159 


9165 


9170 


9175 


9180 


9186 


i 


z 


2 


2 


3 


3 


4 


4 


5 


83 


9191 


9ig6 


9201 


9206 


9212 


9217 


9222 


9227 


9232 


9238 


i 


z 


2 


2 


3 


3 


4 


4 


5 


84 


9 2 43 


9248 


9253 


9258 


9263 


9269 


9274 


9279 


9284 


9289 


z 


z 


2 


2 


3 


3 


4 


4 


5 


85 


9294 


9299 


0304 


9309 


9315 


9320 


9325 


9330 


9335 


9340 


i 


z 


2 


2 


3 


3 


4 


4 


5 


86 


9345 


9450 


0355 


9360 


9365 


9370 


9375 


9380 


9385 


9390 


i 


z 


2 


2 


3 


3 


4 


4 


5 


87 


9395 


9400 


9405 


9410 


9415 


9420 


9425 


9430 


9435 


9440 





z 


I 


2 


2 


3 


3 


4 


4 


88- 


9445 


9450 


9455 


9460 


9465 


9469 


9474 


9479 


9484 


9489 





z 




2 


2 


3 


3 


4 


4 


89 


9494 


9499 


9504 


9509 


9513 


95i8 


9523 


9528 


9533 


9538 





z 




2 


2 


3 


3 


4 


4 


90 


9542 


9547 


9552 


9557 


9562 


9566 


9571 


9576 


958i 


9586 





z 




2 


2 


3 


3 


4 


4 


Qi 


9590 


9595 


9600 


9605 


9609 


9614 


9619 


9624 


9628 


9633 





z 




2 


2 


3 


3 


4 


4 


92 


9638 


9643 


9647 


9652 


9657 


9661 


9666 


9671 


9675 


9680 





z 




2 


2 


3 


3 


4 


4 


93 


9685 


9689 


9694 


9699 


9703 


9708 


9713 


9717 


9722 


9727 


o 


z 




2 


2 


3 


3 


4 


4 


94 


9731 


9736 


9741 


9745 


9750 


9754 


9759 


9763 


9768 


9773 





z 




2 


2 


3 


3 


4 


4 


95 


9777 


9782 


9786 


9791 


9795 


9800 


9805 


9809 


9814 


9818 


o 


z 




2 


2 


3 


3 


4 


4 


96 


9823 


9827 


9832 


9836 


9841 


9845 


9850 


9854 


9859 


9863 





z 




2 


2 


3 


3 


4 


4 


97 


9868 


9872 


9877 


9881 


9886 


9890 


9894 


9899 


9903 


9908 


o 


z 




2 


2 


3 


3 


4 


4 


98 


9912 


9917 


9921 


9926 


9930 


9934 


9939 


9943 


9948 


9952 


o 


z 




2 


2 


3 


3 


4 


4 


99 


9956 


9961 


9965 


9969 


9974 


9978 


9983 


9987 


9991 


9996 





z 




2 


2 


3 


3 


3 


4 



310 



ANTILOGARITHMS 



Log. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


PROPORTIONAL PARTS. 


1 2 


3 


4 





6 


7 


8 


9 














IOI 2 


IOI J 


1016 


IOIO 


IO2I 


















.01 


1023 


1026 


1028 


1030 


1033 


1035 


i3* 


1040 


1042 


I04S 





i 


i 


I 


i 


2 


2 


2 


.02 


104 


1050 


1052 


*054 


1057 


1059 


1062 


1064 


1067 


1069 


o o 


i 


i 


I 


i 


2 


2 


2 


03 


1072 


1074 


1076 


1079 


1081 


1084 


io8f 


1089 


1091 

1 1 17 


IO94 
1 1 IQ 


O 


i 


i 


I 


i 


2 


2 


2 


.04 


1096 


1099 










TT3S 




T T A3 


1 146 


















S 
.06 


1148 


,Si 


1127 

"53 


1130 
1156 


1132 
1150 


IT 35 
1161 


1130 
Il64 


1167 


Il69 


1172 


D I 


i 


i 


i 


2 


2 


2 


2 


.07 


H75 


1178 


1180 


1183 


1186 


1189 


IIQI 


1194 


1197 


1199 


3 I 


i 


i 


I 


2 


2 


2 


2 


.08 


1202 


1205 


1208 


I2II 


1213 


1216 


1219 


1222 


1225 


1127 


a i 


i 


i 


I 


2 


2 


2 


3 


.09 


1230 


1233 


1236 


1239 


1242 


1245 


1247 


1250 


1253 


1256 


3 I 


i 


i 


I 


2 


2 


2 


3 


.10 


1259 


1262 


1265 


1268 


1271 


1274 


1276 


1279 


1282 


1285 


D I 


i 


i 


I 


2 


2 


2 


3 


.11 


1288 


1291 


1294 


1297 


1300 


1303 


1306 


1309 


1312 


I 3 I S 


~t I 


i 


r 


2 


2 


2 


2 


3 


.12 


1318 


1321 


1324 


1327 


1330 


1334 


1337 


1340 


1343 


M46 


D I 


i 


i 


2 


2 


2 


2 


3 


13 


I34Q 


1352 


1355 


1358 


1361 


1365 


1368 


1371 


1374 


1377 


D I 


i 


i 


2 


2 


2 


3 


3 


14 


1380 


1384 


1387 


1390 


1393 


1396 


1400 


M03 


1406 


1409 


3 I 


i 


i 


2 


2 


2 


3 


3 


IS 


1413 


1416 


1419 


1422 


1426 


1429 


1432 


1435 


1439 


1442 


) I 


i 


i 


2 


2 


2 


3 


3 


.16 


1445 


1449 


1452 


1455 


1459 


1462 


1466 


1469 


1472 


1476 


5 I 


i 


i 


2 


2 


2 


3 


3 


-17 

18 


1479 

T CT/I 


1483 


1486 

T C9 T 


1489 


1493 


1496 


1500 


1503 
TC7 Q 


1507 
T CA2 


1510 


1 1 


i 


i 


2 


2 


2 


3 


3 


.19 


I 5 I 4 

1549 


I 5 I 7 

!552 


I52I 
1556 


X 5 2 4 
1560 


1528 
1563 


I 53 I 
1567 


I S35 
1570 


1 53 
1574 


1578 


1581 


J I 


i 


i 


2 


2 


3 


3 


3 


.20 


1585 


1589 


1592 


1596 


1600 


1603 


1607 


1611 


l6l4 


1618 


) I 


i 


i 


2 


2 


3 


3 


3 


.21 


1622 


1626 


1629 


l6 33 


1637 


1641 


1644 


1648 


I6 5 2 


1656 


) I 


r 


2 


2 


2 


3 


3 


3 


22 


1660 


Tfif>3 


1667 


1671 


Tfi7C 


1670 


rfi8? 


1687 


l600 


1604 


















23 


1698 

TT-jCJ 


1702 


1706 

TT/lfi 


1710 


lu /5 
1714 


1718 


1722 

TT^O 


1726 

T7fi6 


1730 


1734 


) I 


i 


2 


2 


2 


3 


3 


4 


.24 
2 C 


I 73& 

1778 


1742 
T789 


1740 

T78fi 


I 7S 

T 7OT 


T 754 

T 7O C 


J 758 

T 7OO 


I7O2 

1803 


I70O 

1807 


I77O 

1811 


X 774 
1816 












3 


3 


4 


^5 

.26 


1820 


1702 
1824 


1828 


1791 
1832 


*795 
1837 


1 799 
1841 


lOO^ 
1845 


1849 


1854 


1858 


> I 


i 


2 


2 


3 


1 


3 


4 


.27 


1862 


1866 


I8 7 I 


1875 


1879 


1884 


1888 


1892 


i8 Q7 


1901 


> I 


r 


2 


2 


3 


3 


3 


4 


.28 


1905 


1910 


I9T4 


1919 


1923 


1928 


IQ32 


1936 


1941 


1945 


> I 


i 


2 


2 


3 


3 


4 


4 


.29 


1950 


I9S4 


1959 


1963 


1968 


1972 


1977 


1982 


1986 


1991 


> I 


i 


2 


2 


3 


3 


4 


4 


.30 


1995 


2000 


2004 


2009 


2014 


20l8 


2023 


2028 


2032 


2037 


I 


i 


2 


2 


3 


3 


4 


4 


.31 


2042 


2046 


2051 


2056 


2061 


2065 


2070 


2075 


2080 


2084 


I 


i 


2 


2 


3 


3 


4 


4 


.32 


2089 


2094 


2099 


2IO4 


2109 


2113 


2118 


2123 


2128 


2133 


I 


i 


2 


2 


3 


3 


4 


4 


33 


2138 


2143 


2148 


2153 


2I 5 8 


2163 


2168 


2173 


2178 


2183 


I 


i 


2 


2 


3 


3, 


4 


4 


34 


2188 


2*93 


2198 


2203 


2208 


2213 


2218 


2223 


2228 


2234 


I 


2 


2 


3 


3 


4 


4 


5 


35 
16 


2239 

2 2O I 


2244 

2206 


2249 
2 7OI 


2254 
23O7 


2259 

2312 


2265 

27f7 


2270 
23.23. 


2275 

2328 


2280 

23.77 


2286 

23. 3.O 


I 


2 


2 


3 


3 


4 


4 


S 


37 
38 


2344 

23.OO 


2350 

24O4 


2355 
24IO 


2360 
241 C 


2366 

2A2I 


2371 
2/127 


6 6 
2377 
2/172 


2382 

243.8 


2388 

24.4.3. 


2393 
244O 


I 


2 


2 


4 


3 


4 


4 


S 


3.0 


2 AC C 


460 


2466 


2A72 


2/L77 


2-182 


2A8o 


2AOC 


2 COO 


2<ro6 


















oV 

4O 


^455 

2CT2 


u8 


l?27 


2C2O 


C7 e 


2 CAT 


2CJ.7 


2CC3 


2CCQ 


2 c64 


I 
















.41 


2570 


576 


0^0 
582 


2588 


594 


2600 


606 


2612 


618 


2624 


I 


2 


2 


3 


4 


4 


> 


S 


.42 


2630 


636 


6 4 2 


2649 


655 


266l 


667 


2673 


679 


2685 


I 


2 


2 


[ 


4 


4 


S 


6 


43 


2692 


698 


704 


2710 


716 


2723 


729 


2735 


742 


2748 


T 


2 


3 


3 


4 


4 


*J 


6 


.44 


2754 


76i 


767 


2773 


780 


2786 


793 


2799 


805 


812 


1 


2 


3 




4 


4 


! 


6 


45 


2818 


825 


831 


2838 


844 


2851 


858 


2864 


871 


877 


r 


2 


3 


3 


4 


s 


s 


6 


.46 


2884 


891 


897 


2904 


911 


2917 


924 


2931 


93 


944 


I 


2 


3 




4 


5 


5 


6 


47 


2951 2958 


Q6,S 


2972 


979 


2985 


992 


2999 


006 


013 


I 


2 


3 


^ 


4 


c; 


S 


6 


.48 


30203027 


034 


3041 


048 


W>5 


062 


3069 


076 


3083 


I 


2 


3 


4 


4 


5 


6 


6 


49 


3090(3097 


105 


3"2 


119 


3126 


133 


3141 


148 


155 


I 


2 


3 


4 


4 


S 


6 


6 



ANTILOGARITHMS 



311 



Log. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


PROPORTIONAL PARTS. 


13345 


6789 


5 


316; 


317 


3i7: 


3184 


3i9 


3I9C 


320 


321 


322 


3228 


I I 2 3 


4 6 7 


51 


323* 


324 


3251 


325* 


326 


3*7.< 


328 


328 


3296 


3304 


1223 


556? 


52 


33U 


33i 


3327 


3334 


334 


335^ 


335 


336 


3373 


338i 


1223 


5567 


53 


338S 


339 


3404 


3412 


3420 


342* 


343 


344 


345 


3459 


1223 


5667 


54 


3467 


347 


3483 


349i 


3499 


35oS 


35i 


352 


3532 


3540 


1223 


5667 


55 


3548 


355 


3565 


3573 


358i 


358g 


359 


3606 


3614 


3622 


I 2 2 3 i 


5677 


56 


3631 


3639 


3648 


3656 


3664 


3673 


368 


3690 


3698 


3707 


1233 


56 8 


57 


3715 


3724 


3733 


374i 


3750 


375 


376 


3776 


3784 


3793 


1233 


5678 


.58 


3802 


381 


3819 


3828 


3837 


3846 


3855 


3864 


3873 


3882 


1234 


5678 


59 


3890 


3899 


3908 


39i 


3920 


3936 


3945 


3954 


3963 


3972 


1234 


5678 


.60 


398i 


3990 


3999 


4009 


4018 


4027 


403^ 


4046 


4055 


4064 


12345 


6678 


.61 


4074 


4083 


409. 


4102 


4111 


4121 


4130 


4140 


4150 


4159 


12345 


6789 


.62 


4169 


4178 


4188 


4198 


4207 


4217 


4227 


4236 


4246 


4256 


12345 


6789 


63 


4266 


4276 


4285 


4295 


4305 


4315 


4325 


4335 


4345 


4355 


12345 


6789 


.64 


4365 


4375 


4385 


4395 


4406 


4416 


4426 


4436 


4446 


4457 


1234 5 


6789 


65 


4467 


4477 


4487 


4498 


4508 


4519 


4529 


4539 


4550 


456o 


12345 


6789 


.66 


457i 


458r 


4592 


4603 


4613 


4624 


4634 


4645 


4656 


4667 


12345 


6 7 9 10 


.67 


4677 


4688 


4699 


4710 


4721 


4732 


4742 


4753 


4764 


4775 


12345 


7 8 9 10 


.68 


4786 


4797 


4808 


4819 


4831 


4842 


4853 


4864 


4875 


4887 


12346 


7 8 9 10 


.69 


4898 


4909 


4920 


4932 


4943 


4955 


4966 


4977 


4989 


5000 


t2356 


7 8 9 IO 


.70 


5012 


5 2 3 


035 


5047 


5058 

CT76 


5070 
5188 


5082 
c?nn 


5093 


5105 


5H7 

C2?6 


c 2 4 5 6 


7 8 9 II 


7 1 

fjiy 


129 

2A& 


140 
260 


I 5 2 

272 


528^ 


5 * 7 

C2O7 


C 2QC 


5 2O 
C22T 


(?72'2 


5224 
c 2/1.6 


5 2 3 
t?2eS 




' 1 .c ci 


7* 
73 


*4 
370 


3*uw 
5383 


* / ^ 

395 


540* 


j-^y / 

5420 


o'-'v 

433 


OO* A 

5445 


J-JOt 
5458 


oo^- u 

5470 


o30 
5483 


3456 


8 9 10 ix 


74 


495 


5508 


521 


5534 


5546 


559 


5572 


585 


5598 


6 10 


3456 


8 9 10 12 


-75 


623 


5636 


649 


5662 


5675 


689 


5702 


715 


5728 


74i 


3457 


8 9 10 12 


.76 


754 


5768 


78i 


5794 


5808 


821 


5834 


8 4 8 


5861 


875 


3457 


8 911 12 


77 


888 


S902 


916 


5929 


5943 


957 


5970 


98 4 


5998 


6012 


3457 


8 10 II 12 


.78 
^ro 


026 
166 


6039 
6l8o 


053 

TQA 


6067 
5 200 


6081 

)223 


095 

217 


6109 
62*2 


6l24 
266 


6138 

6281 


6152 

20 <j 


3467 


8 10 II 13 


79 
.80 


310 


6324 


*-y t \ 

339 


v^<*ry 

6353 


V *^O 
6368 


*OI 
383 


u^z 

6397 


412 


427 


u ^vo 

442 


3467 


9 10 12 13 


.81 


457 


6471 


486 


6501 


6516 


531 


6546 


561 


577 


592 


3568 


9 II 12 14 


.82 


607 


6622 


637 


6653 


6668 


68 3 


6699 


714 


730 


745 


3568 


9 ii 12 14 


.83 


761 


6776 


792 


6808 


6823 


839 


6855 


871 


887 


902 


3568 


9 II 13 14 


.84 


918 


6934 


950 


6966 


6982 


998 


7015 


031 


047 


063 


3568 


on 13 IS 


85 


079 


7096 


112 


7129 


7145 


161 


7178 


194 


211 


228 


3578 


12 13 IS 


.86 


244 


726l 


2 7 8 


7295 


73U 


328 


7345 


362 


379 


396 


3578 


12 13 IS 


87 


413 


7430 


447 


7464 


7482 


499 


75i6 


534 


551 


568 


3579 


o 12 14 16 


.88 


586 


7603 


621 


7638 


7656 


674 


7691 


709 


727 


745 


4579 


I 12 14 16 


.89 


762 


7780 


798 


7816 


7834 


852 


7870 


889 


907 


925 


4579 


I 13 14 16 


.90 


943 


7962 


980 


7998 


8017 


035 


8054 


072 


8091 


no 


4679 


I 13 15 17 


.91 


128 


SI47 


166 


8185 


1204 


222 


$241 


260 


279 


299 


.689 


I 13 IS 17 


.92 


3i8 


3337 


356 


8375 


?395 


414 


8433 


453 


472 


492 


. 6 8 10 


2I4I5 7 


93 


5" 


3531 


551 


3570 


8590 


610 


8630 


650 


670 


690 


. 6 8 ro 


2 14 16 18 


.94 


710 


3730 


750 


3770 


3790 


810 


8831 


8*1 


872 


892 


. 6 8 10 


2 14 16 18 


95 


913 


*933 


954 


3974 


^995 


016 


^036 


057 


078 


099 


. 6 8 10 


2 15 17 19 


.96 


120 


^141 


162 


5183 


3204 


226 


?247 


268 


290 


3ii 


4 6 8 ii 


3 15 17 19 


97 


333 


?354 


376 


?397 


3419 


441 


5462 


484 


506 


528 


4 7 9 ii 


3 15 17 20 


.98 


550 


?572 


594 


p6i6 


^638 


661 


3683 


705 


727 


750 


4 7 9 II 


3 16 18 20 


99 


772 


?795 


817 


3840 


?86 3 


886 


?9o8 


93i 


954 


977 


5 91 


4 16 8 20 



312 LIST OF APPARATUS FOR GENERAL ORGANIC CHEMISTRY 

LIST OF APPARATUS FOR GENERAL ORGANIC 
CHEMISTRY l 

Box I ARTICLES RETURNABLE 

Cat. No. 2 

Addition tube Emil Greincr 

Adapter tube E. & A. no 

Beaker, lipped, Griffin's low form, 50 cc E. & A. 737 

Beaker, lipped, Griffin's low form, 100 cc E. & A. 737 

Beaker, lipped, Griffin's low form, 150 cc E. & A. 737 

Beaker, lipped (Pyrex), Griffin's low form, 250 cc E. & A. 737 

Beaker, lipped, Griffin's low form, 400 cc E. & A. 737 

Beaker, lipped, Griffin's low form, 600 cc E. & A. 737 

Beaker, lipped, Griffin's low form, 800 cc E. & A. 737 

Beaker, lipped, Griffin's low form, 1000 cc E. & A. 737 

6 Bottles, sq., G. S., for handing in liquid preparations, 15 cc E. & A. 926 

6 Bottles, wide-mouthed, glass-stoppered, round, 10 cc., for handing 

in solid preparations E. & A. 034 

2 Bottles, tincture, narrow mouth, G. S., 250 cc E. & A. 918 

3 Bottles, wide mouth, 250 cc E. & A. 910 

i Calcium chloride tube, 6-inch E. & A. 7052 

i Condenser, sealed joints, bulbed inner tube, 12 inches long E. & A. 2246 

i Condenser, straight inner tube E. & A. 2243 

i Condenser, inner tube, "air condenser," i5-inch E. & A. 2240 

i Watch glass, 3-inch (cover glass) E. & A. 7382 

i Watch glass, 42-inch (cover glass) E. & A. 7382 

i Bottle, sealing tube, 15 cc 

i Cylinder, graduated, 100 cc E. & A. 2512 

i Cylinder, graduated, 10 cc E. & A. 2512 

1 Evaporating dish, pore., 6 cm. diam. (Coors) E. & A. 501 

2 Flasks, distilling, round bottom, 30 cc. (Pyrex) E. & A. 3065 

2 Flasks, distilling, B. & C., round bottom, 50 cc. (Pyrex) E. & A. 3065 

2 Flasks, distilling, B. & C., round bottom, 125 cc. (Pyrex) E. & A. 3065 

1 Flask, distilling, B. & C., round bottom, 250 cc. (Pyrex) E. & A. 3065 

2 Flasks, Erlenmeyer, 150 cc E. & A. 3027 

2 Flasks, Erlenmeyer, 50 cc E. & A. 3027 

i Flask, Erlenmeyer, 250 cc E. & A. 3027 

Flask, heavy glass, for filtering, with side neck, 500 cc E. & A. 3090 

Glass evaporating-dish, 5 cm E. & A. 2624 

Flask, round bottom, 125 cc E. & A. 3050 

Flask, round bottom, 250 cc E. & A. 3050 

Flask, round bottom, 300 cc., short neck E. & A. 3057 

Flask, round bottom, 500 cc E. & A. 3050 

Flask, round bottom, 1000 cc E. & A. 3050 

Funnel, 4 cm. diam E. & A. 3216 

1 See preface, p. v. 

2 These are given for the sake of convenience only. 



LIST OF APPARATUS FOR GENERAL ORGANIC CHEMISTRY 313 

Cat. No. 

Funnel, 7.5 cm. diam., short stem, special E. & A. 3216 

Funnel, dropping, 60 cc E. & A. 3302 

Funnel, separatory, Squibb's, 250 cc E. & A. 3300 

Funnel, Buchner, porcelain, 5 cm. diam. (Coors) E. & A. 630 

Gooch perforated plate 

i Set of three thermometers, short scale, with case (Fisher) E. & A. 

1 Thermometer, milk glass scale, 360 C E. & A. 6746 

6 Test-tubes, 4"X" E. & A. 7210 

12 Test-tubes, 6"X2" E. & A. 7216 

3 Test-tubes, 8"Xi" E. & A . 7216 

2 Test-tubes, side neck, 6" X i " E. & A. 7218 

i Melting-point apparatus 

i Hard glass test-tube, Pyrex, special, 10 cm.Xg mm 

i Mortar, glass lipped, 2-J inches E. & A. 4616 

i Pestle for above, glass E. & A. 4616 

i Spatula and spoon combined, pore., 12 cm Coors, 55.5 

1 Glass stop-cock, 2 mm E. & A. 6468 

Box II ARTICLES RETURNABLE 

Cat. No. 

2 Burette clamps, iron E. & A. 2006 

2 Burners, Tirrill E. & A. 1462 

i Burner chimney E. & A. 1586 

1 Burner, star support for chimney E. & A. 1608 

2 Condenser clamps, iron, large E. & A. 2020 

2 Condenser clamps, iron, medium. . E. & A. 2016 

4 Clamp holders, for -j\-inch rods. . . E. & A. 2044 

i Set of rings for steam-bath . . 

i Filter pump with special Columbia coupling medium, 4} inches.. E. & A. 5624 

1 Oil bath, iron, 6-inch, modified E. & A. 616 

2 Ring stands, medium, iron, modified in shop E. & A. 6540 

i Ring for iron stand, 2 inches E. & A. 6010 

i Ring for iron stand, 3 inches E. & A. 6010 

i Set cork borers, Nos. 1-9 brass (Old Cat.) E. & A, 2841 

i Screw clamp E. & A. 2080 

i Test-tube rack, copper *. 

i Tripod, 4^ inches diam E. & A. 7000 

i Wing top for burner E. & A. 1616 

1 Set weights, rental .75 (Columbia Style B) 

The following pieces of apparatus are too large to go into the packing box, 
but the student will need them immediately, therefore he should go to the 
Stockroom and draw them at once on a new debit card. 

2 Ring stands, large, iron, extra heavy, modified in shop E. & A. 6040 

The following and other apparatus may be obtained at the Stockroom at any 

time as needed: 

Manometer stand Porcelain casseroles 

Hot-water funnel Evaporating dishes 



314 LIST OF APPARATUS FOR GENERAL ORGANIC CHEMISTRY 

Funnels, Nos. 5 and 6 (i 2 cm. and 1 5 cm.) Special distilling-flasks 
Electric motor Instruments 

Stirring apparatus Glass stop-cocks 

Desiccators Large condensers, bulbed or straight inner 

Wind shields tubes 

Etc. 

Box II ARTICLES NON-RETURNABLE 

Cat. No. 
4 Lengths glass tubing, 6 mm. bore, 2\ ft E. & A. 3730 

2 Lengths glass rod, 4 mm. bore, 2\ ft E. & A. 3726 

3 Porous tiles 

i File, rat tail, 5 inches E. & A. 2864 

i File, rat tail, 7 inches E. & A. 2864 

1 File triangular, 5 inches E. & A. 2866 

Wire gauze, 4 inches square E. & A. 7450 

Steel spatula, 7.5 cm E. & A. 6272 

Sodium knife (common knife) E. & A. 2300 

Test-tube brush, sponge end E. & A. 1 210 

Test-tube cleaner E. & A. 1214 

Package filter paper, 12 \ cm., Whatman No. 2 E. & A. 5001 

2 Boxes matches 

i Test-tube holder, nickel E. & A. 2068 

i Sponge E. & A. 6378 

1 Box labels, square E. & A. 

2 Towels 

8 Feet black rubber tubing, & inch I. D E. & A. 6054 

12 Feet white rubber tubing, J inch I. D., heavy walled E. & A. 6048 

1 Pair goggles, wire gauze protectors E. & A. 3794 

2 Dozen assorted corks, sizes 1-15 E. & A. 2284 

i Suberite ring, 2\ inches I. D E. & A. 6020 

i Cake Pummo soap 

1 Tin pail 

2 Locks with keys, Eagle Lock Co 

i Vial litmus paper, neutral, Squibb's 

i Pocket ruler 

Rubber stopper No. 7, 3 holes, to fit 250-00. bottle E. & A. 6040 

Rubber stopper No. 5, i hole, to fit test-tube, with side neck E. & A. 6040 

Rubber stopper, 3 holes to fit 250-00. short neck R. B. flask. ... E. & A. 6040 

Rubber stopper, No. 5, 2 holes to fit test-tube with side neck. . . E. & A. 6040 

Scissors E. & A. 6104 

Cork screw, Williamson Wire Novelty Co pj 

Rubber washer 

i Perfection sand paper holder H. & S. 1017 

i Package sand paper, 4i"X4j" 1 

1 For keeping Alberene desk top clean. 



LIST OF CHEMICALS FOR LONG COURSE 



315 



LIST OF CHEMICALS FOR LONG COURSE 1 

FIRST SEMESTER 



Reagent 

No. 


Name and Specification. 


Amount. 


Kind of 
Container. 


I 


Acetone 


30 cc. 


G. S. B. 2 


2 


Acetophcnone 


10 gms. 


G. S. B. 


3 


Alcohol, 95% 


2X300 cc. 3 


G. S. B. 


4 


Amyl alcohol (iso) 


I CC. 


G. S. B. 


S 
6 

7 


Aniline from sulfate for B. P. determination 
Anisic acid, powdered, for M. P. determi- 
nation 
Anthracene, powdered, for M. P. determi- 
nation 


15 cc. 
o.i gm. 
o i gm. 


G. S. B. 
Vial 
Vial 


8 


Anthraquinone, powderr d, for M. P. deter- 
mination 


o. i gm. 


Vial 


g 


Benzine, 7080 


15 cc. 


G. S. B. 


IO 


Bcnzoic acid 


i gm. 


Vial 


II 


Benzoic acid, powdered, for M. P. determi- 
nation ... 


o. i gm. 


Vial 


12 


Bromine 


I OZ. 


G. S. B. 


17 


Bromine water .... 


25 cc. 


G. S. B. 


14 
15 


Bromine, 5% in carbon tetrachloridc .... 
Calcium chloride, anhyd., gran 


20 cc. 
loo gms. 


G. S. B. 
C. S. B. 2 


16 


Calcium carbide, lumps 


15 gms. 


C. Vial 


17 


Calcium oxide 


150 gms. 


WM., G. S. B. 2 


18 


Carbazol, powdered, for M. P. determina- 
tion ' . . . 


o. i gm. 


Vial 


IO 


Chloroform 


IO CC. 


G. S. B. 


20 


Copper oxide powder 


2 gms. 


Vial 


21 


Copper sulfate anhyd .... 


j cms. 


C. Vial 


22 


Copper sulfate crystals * 


i gm. 


Vial 


27 


Copper sulfate, ^j- molar 


3 cc. 


C. S. B. 


24. 


Copper turnings 


5 gms. 


Vial 


2C 


Copper wire 


2ft. 


Vial 


26 


Cotton, absorbent 


2 gms. 


Vial 











1 See preface, p. v. 

2 Abbreviations: G. S. B. = glass stoppered bottle; C. S. B. = cork stoppered bottle; 
WM. wide-mouthed. 

3 The amounts of such reagents as alcohol, ether, sulfuric acid are only nominal. These 
must be added to later in the work. 



316 



LIST OF CHEMICALS FOR LONG COURSE 



LIST OF CHEMICALS FOR LONG COURSE Continued 
FIRST SEMESTER 



Reagent 
No. 


Name and Specification. 


Amount. 


Kind of 
Container. 


27 


Di-nitrobenzoic acid (1*3*5) 


I gm. 


Vial 


28 


Ether, Merck's 


aXi lb. 


Cans 


2O 


Ethyl bromide 


35 cc - 


C. S. B. 


TO 


Fehling's solution A l 


5 cc. 


G. S. B. 


2T 


Fehling's solution, B 


5 cc. 


G. S. B. 


72 


Formalin 


25 re. 


G. S. B. 


77 


Glass wool 


20 cc. 


Vial 


?A 


Glycerol 


10 cc. 


C. S. B. 


7C 


Hydrochloric acid, cone 


35 c c. 


G. S. B. 


7,6 


Hydro xylamine hydrochloride 


3 . 5 gms. 


WM., G. S. B. 


77 


Iodine 


17 gms. 


WM., G. S.B. 


7,8 


Lime water 


10 cc. 


C. S. B. 


7Q 


Magnesium (Grignard's) 


5 gms. 


Vial 


4O 


Menthol 


5 gms. 


C. Vial 


41 


Methylal . 


2 CC. 


S. T. 2 


4.2 


Methyl alcohol 


2 CC. 


C. S. B. 


43 


Naphthalene, powder, for M. P. determi- 
nation . . 


o i gm. 


Vial 


AA 


Phenolphthalein, sol 


5 cc. 


C. S. B. 


AC 


Phosphoric acid (17) 


40 cc. 


G. S. B. 


46 


Phosphorus pcntachloride 


i gm. 


S. T. 


47 


Phosphorus red 


2 gms. 


Vial 


48 


Pinene 


is cc. 


C. S. B. 


4Q 


Porous tile, gran . ... 


10 gms. 


Vial 


CO 


Potassium carbonate, fused 


15 gms. 


C. Vial 


CT 


Potassium hydroxide. . . 


> Ems. 


C. Vial 


52 

JT7. 


Potassium hydroxide, purified by alcohol . . 
Potassium permanganate 


3 gms. 
2 gms. 


C. Vial 
Vial 


54 


Quinoline (synthetic) for B. P. determina- 
tion 


15 cc. 


G. S. B. 


<z 


Rapeseed oil 


300 cc. 


C. S. B. 


56 


Resorcinol solution, 0.5%) 


2 CC. 


C. S. B. 


57 


Salicylic acid, powder, for M. P. determi- 
nation . . 


o. i fzm. 


Vial 


58 


Schiff s aldehyde reagent (fuchsine sulfur- 
ous acid) 


10 cc. 


G. S. B. 


CQ 


Soda lime, dry 


20 cc. 


C. Vial 


60 


Sodium bicarbonate 


5 gms. 


Vial. 











1 The ground part of the glass stopper of the bottle containing the "alkaline half" of 
Fehling's solution is dipped in melted paraffin before being used. This prevents the stopper 
from becoming ''frozen." Cork and rubber stoppers cannot be used. 

2 S. T. = sealed tube. 



LIST OF CHEMICALS FOR LONG COURSE 



317 



LIST OF CHEMICALS FOR LONG COURSE Continued 
FIRST SEMESTER 



Reagent 
No. 



Name and Specification. 



Amount. 



Kind of 
Container. 



Oi Sodium bichromate 45 gms. 

62 Sodium bisulfite, sat. sol 5 cc. 

63 Sodium carbonate, dry 5 gms. 

64 Sodium chloride, sat. sol 50 cc. 

65 Sodium hydroxide 50 gms. 

66 Sodium, metallic 12 gms. 

67 Sulfuric acid, cone 300 cc. 

68 Sulfuric acid, fuming 15 cc. 

6q Vaseline 10 cc. 

70 Zinc dust 10 gms. 



Vial 
C. S. B. 

Vial 
C. S. B. 
C. Vial 

WM., G. S. B. 
(in can) 
G. S. B. 

S. T. 

Vial 

Vial 



318 



LIST OF CHEMICALS FOR LONG COURSE 



LIST OF CHEMICALS FOR LONG COURSE 1 
SECOND SEMESTER 



Reagent 
No. 


Name and Specification. 


Amount. 


Kind of 
Container. 


I 


Acetic acid (glacial) 


*7C CC 


GS T* i 


2 


Acetic anhydride 


12 CC 


GSR 


3 


Acetylacetone 


I CC 


G S B 


4 


Acetacetic ester 


I CC 


G S B 




Acetone 


2 (J CC 


P <s T* 


6 


Alcohol, 95% 


*5 *-'- 

2X3 cc 1 


C S B 


7 


Aluminium chloride (anhyd.) 


5 gms 


C Vial 


8 


Ammonium acetate (dry) 


i ? urns 


C Vial 


9 


Ammonium hydroxide, cone 


50 cc 


G S B 


10 


Ammonium molybdate reagent 


2J CC 


G S B 


ii 


Aniline I 


Sec 


G S B 


12 


Animal charcoal 


S crms 


Vial 


13 


Anthracene 


2r CTTY| 


Vial 


14 


Benzene, 8o-82 


115 cc 


C S B 


15 


Benzene, thiophene free 


3CC 


G S B 


16 


Benzaldehyde 


Sec 


C S B 


17 


Benzyl chloride 


I % CC 


S tube 


18 


Bleaching powder 


SormS 


C vial 


19 


Bromine 


I OZ 


G S B 


20 


Bromine water 


IO CC 


G S B 


21 


Bromine in CCh, 5% 


I CC 


G S B 


22 


Butter 


10 cms 




23 


Cane sugar 


5 firms- 


Vial 


24 


Carbon disulfide 


I CC 


C S B 


25 


Catechol 


o i gm 


Vial 


26 


Chloroform, U.S.P 


20 cc 


C S ft 


27 


Chromium trioxide 


4{? cms 


C vial 


28 


Cinnamic acid 


o i gm 


Vial 


29 


Copper carbonate (basic) 


o c crm 


Vial 


3 


Copper sulfate N 


7CC 


C S B 


31 


Corn cob (ground) 


i gm 


Vial 


32 


Cotton (absorbent) 


o < cm 


Vial 


33 


Dimethylaniline. . 


2 CC 


G S B 


34 


Dimethyl sulfate .... 


30 gms 


S tube 


35 


Diphenyl-thiourea 


o 01 gm 


Vial 


36 


Egg 


j 


Shell 


37 


Ether (Merck's) 


2Xi Ib. 1 


Cans 


38 


Ether ("over sodium") 


90 cc. 


C S B 


39 


Ethyl ammonium chloride 


2 CC. 


C S B 











1 See .foot-notes, p. 315. 



LIST OF CHEMICALS FOR LONG COURSE 



319 



LIST OF CHEMICALS FOR LONG COURSE Continued 
SECOND SEMESTER 



Reagent 
No. 


Name and Specification. 


Amount. 


Kind of 
Container. 


AQ 


Ethyl bromide . . /. . . 


20 cc. 


C S B 


AT 


Fehling's solution "A" 


TC re. 


G S B 1 


A.2 


Fehling's solution ' ' B " 


7C cc. 


G. S B 


A? 


Ferric chloride, molar 


< CC. 


C. S B. 


A A 


Ferric chloride, N 


2 CC. 


C. S B 


AC 


Ferrous sulfate 


i gm 


Vial 


45 
4,6 


Ferrous sulfide 


20 gms. 


Vial 


47 


Gallic acid 


o 01 gm. 


Vial 


48 


Gelatine 


i gm. 


Envelope 


AQ 


Gum arabic 


o. 5 gm. 


Vial 


*JO 


Hydrochloric acid, cone .... 


125 cc. 


G S B 


CT 


Hippuric acid 


i cm. 


Vial 


<2 


Iron powder 


c gms. 


Vial 


C7 


Iron nails (small) 


3 cms 


Vial 


CA 


Lactose . . 


1 2 gms 


Vial 


ee 


Lead acetate. N 


10 cc. 


C S B 


r6 


Magnesium sulfate, cryst 


6 gms. 


Vial 


17 


Methyl iodide 


I CC. 


S tube 


eg 


Michler's ketone 


o. i gm. 


Vial 


to 


Monomethyl aniline commercial 


I CC 


G S B 


60 


Nitric acid cone 


60 cc 


G S B 


61 


Nitric acid, fuming 


I CC. 


S tube 


62 


Nitrobenzene, commercial 


20 cc. 


C S B 


6* 


Phenol 


i ? gms 


Vial 


64 


Phthalic anhydride 


o 2 gm. 


Vial 


6c 


Phenylhydrazine 


2 cc. 


G S B 


66 


Phosphorus oxy chloride 


2 CC. 


S tube 


67 


Phosphorus trichloride 


1 CC. 


S tube 


68 


Potassium carbonate (fused) 


2 1 cms 


C vial 


60 


Potassium cyanate 


o c ir. 


Vial 


7O 


Potassium fluoride 


o c c. 


Vial 


71 


Potassium iodide N/io 


2 CC 


C S B 


72 


Potassium permanganate 


10 gms. 


Vial 


73 


Potassium ethyl sulfate 


o < em. 


Vial 


74. 


Pyridine, commercial 


5CC 


G S B 


75 


Quinoline 


VA-. 

2 CC. 


G S B 


76 


Resorcinol 


o i gm 


Vial 


77 


Salicylic acid 


o i gm 


Vial 


78 


Schiff's aldehyde reagent 


20 cc 


Amb G S B 











i See foot-note, p. 316. 



320 



LIST OF CHEMICALS FOR LONG COURSE 



LIST OF CHEMICALS FOR LONG COURSE Continued 

SECOND SEMESTER 



Reagent 
No. 



Name and Specification. 



Amount. 



Kind of 
Container. 



79 Silver nitrate, N/io * 10 cc. 

80 Sodium, metallic 12 gms. 

81 Sodium bisulfite, sat. sol . 10 cc. 

82 Sodium carbonate, cryst 4 gms. 

83 Sodium chloride, commercial 4 Ibs. 

84 Sodium chloride, sat. sol 50 cc. 

85 Sodium dichromate 15 gms. 

86 Sodium hydroxide 50 gms. 

87 Sodium nitrite 8 gms. 

88 Sodium nitroprusside o. i gm. 

89 Starch, soluble 5 gms. 

90 Sulfanilic acid i gm. 

91 Sulfuric acid (fuming) 6 cc. 

92 Tannin (tannic acid) 2 gms. 

93 Tin, granulated 35 gms. 

94 Toluene, commercial no cc. 

95 Toluidine (ortho) 5 cc. 

96 Triphcnyl-chlor-methane o 5 gm. 

97 Xylcne, commercial 30 cc. 

98 Zinc chloride, N 10 cc. 

99 Zinc dust, commercial 5 gms. 

100 Zinc, powdered i gm. 



Amb. G. S. B. 

WM., G. S. B. 

(in can) 

C. S. B. 

Vial 

Bag 
C. S. B. 
C. vial 
C. vial 

Vial 

Vial 

Vial 

Vial 
S. tube 

Vial 

Vial 
C. S. B. 
G. S. B. 

Vial 
C. S. B. 
C. S. B. 

Vial 

Vial 



LIST OF CHEMICALS FOR SHORT COURSE 
LIST OF CHEMICALS FOR SHORT COURSE 1 



321 



Reagent 

No. 


Name and Specification. 


Amount. 


Kind of 
Container. 


j 


Acetic acid glacial 


IOO CC 


G S B * 


2 


Acetic anhydride . . . 


I 2 rr 


G S B 




Acetacetic ester 


I CC. 


G S B 




Acetylacetone . . 


I CC 


G S B 


e 


Acetone 


2< CC. 


C. S. B. 1 


6 


Alcohol 95% 


' X 300 cc * 


G S B 


7 


Ammonium acetate 


15 gms. 


C. vial 


8 


Ammonium hydroxide, cone 


50 cc. 


G S B 




Ammonium molybdate, sol 


25 cc. 


G. S. B. 


10 


Amyl alcohol (iso) 


I CC. 


G. S. B. 


II 


Aniline I .... 


15 cc. 


G. S. B. 


12 


Aniline from sulfate, for B. P. determina- 
tion . . ... ... 


jc CC. 


G. S B. 


I 7 . 


Animal charcoal 


i $ cms. 


Vial 


14 


Anthracene, powdered, for M. P. determi- 
nation 


o i gm. 


Vial 


I! 


Benzene 8o-82 . 


1 <\ CC. 


C S B 


16 


Benzene (thiophene free) 


2 CC. 


C. S. B. 


17 


Benzine 7O-8o. 


I C CC 


G S B 


18 


Benzaldehyde 


c CC. 


C S B. 


TQ 


Bcnzoic acid 


i gm 


Vial 


20 


Bleaching powder 


5 ems. 


Vial 


21 


Bromine 


5cc 


G S B 


22 


Bromine water 


2C CC. 


G. S. B. 


23 
2A 


Bromine, 5% in carbon tetrachloridc . . . . 
Butter 


20 CC. 

10 gms. 


G. S. B. 


2<\ 


Calcium chloride, anhydrous, gran. . . 


2c cms 


C. S B. 


26 


Calcium carbide, lumps 


i n gms. 


Vial 


27 


Calcium oxide 


150 gms. 


WM C S B 


28 


Cane sugar 


j gms. 


Vial 


2Q 


Catechol 


o. ; cm. 


Vial 


7Q 


Chloroform . ... 


?o cc. 


G. S. B. 


2T 


Cinnamic acid 


o i gm. 


Vial 


72 


Copper carbonate basic . . 


o s gm. 


Vial 


22 


Copoer oxide, powder 


ej grns. 


Vial 


2A 


Copper sulfate, anhyd 


5 gms. 


C. vial 


7C 


Copper sulfate, cryst 


i gm. 


Vial 


26 


Copper sulfate N sol 


e cc. 


C. S. B. 


27 


Copper turnings 


1 gms. 


Vial 


28 


Copper wire No. 16 


2 ft. 


Vial 


2Q 


Cotton, absorbent 


2 gms. 


Vial 











1 See preface, p; v. and also foot-notes, p. 315. 



322 LIST OF CHEMICALS FOR SHORT COURSE 

LIST OF CHEMICALS FOR SHORT COURSE Continued 



Reagent 
No. 


Name and Specification. 


Amount. 


Kind of 
Container. 


40 


Dimethyl aniline 


2 CC. 


G. S. B. 


41 


Diphenyl-thiourea ... 


o.oi gm. 


Vial 


42 


Egg 


I 


Shell 


43 


Ether (Merck's) 


2XJ Ib. 


Cans 


44 

AC 


Ethyl ammonium chloride, sol 
Ethylene dibromide 


2 CC. 
2 CC. 


C. S. B. 
C. S. B. 


46 


Fehling's solution, "A" 1 


2O CC. 


G. S. B. 


47 


Fehling's solution, "B " 


2O CC. 


G. S. B. 


48 


Ferric chloride, -^ molar 


20 cc. 


C. S. B. 


4O 


Ferrous sulfate 


i gm. 


Vial 


CO 


Ferrous sulfidc 


20 gms. 


Vial 




Gallic acid 


o . i gm. 


Vial 




Glass wool 


20 cc. 


Vial 




Hippuric acid 


i gm. 


Vial 




Hydrochloric acid, cone 


150 cc. 


G. S. B. 


ec 


Hydroxylamine hydrochloride 


i 5 gms. 


WM. G. S. B. 




Iodine resublimed 


17 cms. 


WM G S. B. 


J7 


Iron powder 


5 gms. 


Vial 


eg 


Lead acetate N sol 


10 cc. 


C S B 


en 


Lime water . . 


10 cc. 


C S. B. 


60 


Methyl iodide 


I CC. 


SealT 


61 


Michler's ketone 


o . i gm . 


Vial 


62 


Monomethyl aniline 


I CC. 


C. S. B. 


63 


Naphthalene, powdered, for M. P. deter- 
mination 


o i gm. 


Vial 


64 


Nitric acid, cone 


c,o cc. 


G S B. 


6<? 


Nitric acid, fuming 


I CC. 


SealT 


66 


Nitrobenzene, commercial 


20 cc. 


C S. B. 


67 
68 


Nitrobenzene, for B. P. determination. . . 
Phthalic anhydride 


15 cc. 
o 2 gms. 


C. S. B. 
Vial 


69 


Phenolphthalein sol 


c cc. 


C. S. B. 


70 


Phenylhydrazine 


C CC. 


G. S. B. 


71 


Phosphorus, red 


2 gms. 


Vial 


72 


Phosphorus pentoxide 


4 cms. 


C. vial 


73 


Phosphorus oxychloride 


2 CC. 


SealT 


74 


Phosphorus trichloride 


7 <? CC. 


Seal T. 


75 


Pinene 


15 cc. 


C. S. B. 


76 


Porous tile, small broken pieces 


20 cc. 


C. vial 


77 


Potassium carbonate, anhyd 


20 gms. 


C. vial 


78 


Potassium hydroxide 


5 cms. 


C. vial 


79 


Potassium hydroxide, purified by alcohol . 


3 gms. 


C. vial 



1 See foot-note, p. 316. 



LIST OF CHEMICALS FOR SHORT COURSE 323 

LIST OF CHEMICALS FOR SHORT COURSE Continued 



Reagent 
No. 


Name and Specification. 


Amount 


Kind of 
Container. 


80 


Potassium flouride 


o.<> em. 


Vial 


81 


Potassium iodide, N/io sol 


2 CC. 


C. S. B. 


82 


Potassium permanganate 


5 cms. 


Vial 


83 


Pyridine, commercial 


J CC. 


G. S. B. 


84 


Quinoline 


2 CC. 


G. S. B. 


8<; 


Rapeseed oil 


300 cc. 


C. S. B. 


86 


Rcsorcinol . . . .... 


o 2 cm. 


Vial 


87 


Salicylic acid 


o i gm. 


Vial 


88 
80 


Salicylic acid, for M. P. determination . . 
Schiff's aldehyde reagent 


O.I 

20 


Vial 
Amb. G. S. B. 


oo 


Silver nitrate sol., N/io 


2? CC. 


Amb. G. S. B. 


OI 


Sodium bisulfite, sat. sol 


I<? CC. 


C. S. B. 


02 


Sodium dichromate, commercial 


20 gms. 


C. vial 


Q2 


Sodium chloride sat. sol 


<sO CC. 


C. S. B. 


04. 


Sodium chloride 


loo gms. 


C. S. B. 





Sodium carbonate, cryst 


10 gms. 


Vial 


06 


Sodium hydroxide 


25 gms. 


C. vial 


O7 


Sodium nitrite 


8 gms. 


Vial 


08 


Sodium nitroprusside 


o.oi gm. 


Vial 


OO 


Starch, soluble 


e cms. 


Vial 


IOO 


Sulfanilic acid. . 


i gm. 


Vial 


IOI 


Sulfuric acid, cone . . . 


IOO CC. 


G S. B. 


IO2 


Sulfuric acid, fuming 


10 cc. 


SealT 


IO3 


Tin, gran 


se crnis. 


Vial 


IO4 


Toluidine (ortho) 


* cc. 


G. S. B. 


IO"\ 


Vaseline 


10 cc. 


Vial 


1 06 


Zinc chloride, N/io 


10 cc. 


C S B. 


IO7 


Zinc dust, commercial. . 


10 gms 


Vial 











GENERAL INDEX 



NOTE. Substances with a prefix such as /-menthone, ^-tolunitrile, etc., are 
indexed under the name of the substance regardless of the prefix. 

Addition tube 13 

Alcohol, absolute, preparation of . . 26 

240 boiling-point 24 

for drying apparatus 15 

243 fractionation of mixture 22 

248 , secondary, preparation of 73 

236 , tertiary, preparation of 69 

6 Alcoholic potash, for halogen test.. 38 

Alcohols, identification of 55 

178 , reactions of 54 

Aldehyde ammonia, see Acetalde- 
90 hyde ammonia. 

83 Aldehydes, tests for 91 

85 Alkalies, accidents 6 

94 Alkylation of an hydroxyl group. . . 180 

115 Alumina, preparation of 238 

117 Aluminium chloride, in Friedel- 

C rafts' reaction 144 

189 , opening sealed bottles of. . 144 

mercury couple, reference for.. . 146 
189 oxide, preparation of 238 

6 Amino acid, preparation and prop- 

98 erties 124 

15 acetic acid, preparation of. ... 124 

73 Amylene, in tests for ' double 

164 bond." 45 

178 Aniline, preparation of 157 

164 Animal charcoal for decolorizing 

165 solutions 125, 150, 164, 167 

102 Anisole, preparation of 180 

103 Anthraquinone, preparation of. ... 210 
50 Atomic weights, table of. 

52 Inside back cover. 

50 Autoxidation of benzaldehyde 182 

51 Azotometer, for nitrogen combus- 

50 tion 285 

6 , testing 287 



Absorption bottles, how to fill, for 
water 

Absorption bottles, how to fill, for 
C0 2 

Absorption bottles, weighing 

train 

Accident, in case of 

Acetacetic ester, ferric chloride 

test 

Acetaldehyde, preparation from 

aldehyde ammonia 

, of a solution of 

ammonia, preparation of 

Acetals 

Acetamide, preparation of 

sealed tube method 

0-Acetamino-benzoic acid, prepara- 
tion of 

Acetanilide, formation of 
Acetanthranilic acid, preparation of 

Acetic acid, for accidents 

Acetone, chemical properties of .... 

for drying apparatus 

Acetophenone, reduction of 

Acet-o-toluidide, preparation of . . . 
Acetylacetone, ferric chloride test . . 
Acetylation, with acetic anhydride . 

, acetyl chloride 103-4* 

Acetyl chloride, preparation of. ... 

reactions 

Acetylene, from calcium carbide. . . 

, ethylene dibromide 

, properties of 

Acetylides, cuprous 

, silver 

Acids, accidents 



325 



326 



GENERAL INDEX 



B 

Babo funnel 159 

Barometer, table of corrections for. 300 

Baths for heating, metal 79 

, oil ... 79 

Bending glass tubing 28 

Benzaldehyde, reactions 182 

Benzene, chemical properties 138 

, historical note 139 

sulfonic acid, sodium salt, prepa- 
ration of . . . 152 

Benzidine rearrangement 169 

Benzine, properties 32 

Benzolene, name for benzine 33 

Benzyl chloride, in Friedel-Crafts' 

reaction 144 

, test for halogen in 150 

Blank determinations, method of 

running 246 

Blankets, for fire 6 

Boat, for organic combustions .... 236 

tube ("pigRic "). 251 

Boiling, discussion of . . 17 

Boiling-point, correct 17, 18 

- , correction for change in air 

pressure . . 16 

Boiling-point, definition 17 

, determination of 7 

, liquids for determining 17 

Bomb-tube, how to seal 117 

Boric acid for accidents . .... 6 

Brombenzene, preparation of 149 

Bromination of an aromatic hydro- 
carbon . .... 149 

Bromine, accidents 6 

, bottles, method of opening. . . 33 
Bubble counter. . . ... 227 

Bumping, causes and methods of 

prevention 19 

Butter, hydrolysis of 108 



Calcium chloride for absorbing 
water in organic combustions . . . 239 

for drying liquids, see Dry- 
ing agents. 

Calcium chloride tube, filling 27 



Calculations for carbon and hy- 
drogen 257 

, for nitrogen 300 

Camphene, preparation of 202 

Camphor, preparation of 208 

Cane sugar, hydrolysis of 127 

Carbon, determination of 217 

, tests for 30 

Carbon dioxide generator for nitro- 
gen combustion 275 

Carron oil for accidents 6 

Castor oil for alkali in the eye .... 6 

Catechol, ferric chloride test 178 

Cellulose acetate, formation of. ... 137 

Cerium dioxide, preparation of. ... 234 

Chemicals, amounts 3 

, lists, see List of chemicals. 

, weighing ' 3 

Chromic acid, oxidation with . 54, 83, 85 

99, 210 

Cinnamic acid, decomposition. . 183 

, reduction to hydrocinnamic 

acid ... 184 

Claisen distilling flask 76 

Combustion of gases 268 

explosive substances 269 

liquids. . 267 

substances containing mer- 
cury. . . 267 
Combustion of substances contain- 
ing nitrogen . 265 

Combustion of substances contain- 
ing phosphorus. . . 267 

Combustion of substances contain- 
ing sodium . . . 267 

Combustion of substances contain- 
ing sulfur 266 

Combustion proper, fo: carbon and 

hydrogen. . . 253 

Combustion proper, for nitrogen. . 293 
tube, for the determination of 

carbon and hydrogen 231 

Combustion tube, for nitrogen 284 

Condenser, air 15 

, bulbed 26 

, Liebig 13 

, reflux 26 

, water 10, 13 



GENERAL INDEX 



327 



Copper oxide, gauge, roll of, 

("spiral") 228,235 

Copper oxide, in qualitative test for 

carbon 30 

Copper oxide, preparation of, for 

nitrogen combustion 288 

Copper sulfate, in test for water in 

alcohol 26 

Corks, boring 10 

Crystal violet, formation of 171 

, preparation of 175 

Cuprous chloride solution, ammo- 

niacal 50 

Cuprous cyanide, for Sandmeyer 

reaction 187 



Decolorization with animal char- 
coal 125, 150, 164, 167 

Desiccator, vacuum 87 

Diazotization 170,177,187 

p Dibrombenzene, formation of. ... 150 
// itns-i .8-Dichlor-terpane, prepara- 
tion of 195 

Dimethylaniline, in test for 3- 

amine 165 

Dimethyl-ethyl-carbinol, prepara- 
tion of . . . 60 

Dimethyl sulfate, as alkylating 

agent 180 

Dinitro-benzenc, formation of . .. 130 
3.5-Dinitrobenzoic acid, for identi- 
fication of alcohols 55 

Diphenylmethane, preparation of 144 
Diphenylsulfone, formation of. 138, 152 
Diphenylthiourea, in test for ele- 
ments 112 

Discussion of results, for carbon and 

hydrogen 258 

Discussion of results, for nitrogen. 301 

Distillation, apparatus for 10 

, fractional 22 

in vacua 76 

with steam 158 

Distilling flasks, Claisen 76 

, Ladenburg n, 22 

, ordinary 1 1 

Double bond, tests for. .44,48, 183, 185 



Drying agents for liquids, anhy- 
drous sodium sul- 
fate 177,191 

, calcium chloride. . .37, 154 

, fused potassium car- 
bonate 71, 74 

, solid sodium hydroxide 160 

Drying pieces of apparatus 15 

Dumas method for nitrogen 269 

Dyes, azo, methyl orange 170 

, triphenylmethane, crystal vio- 
let i7i,i7S 

Dyes, triphenylmethane, phenol- 

phchalein 171 

Dyes, triphenylmethane, fluores- 
cein 171 



Electric combustion furnace.. . . 230, 283 

Empirical formula 260 

Emulsions, " breaking," foot-note. 36 
Error, limit of, for carbon and hy- 
drogen 258 

Error, limit of, for nitrogen 301 

Errors in combustions, and how to 

avoid them . . 261 

Ester, formation of an, by addition 

of an acid to an olefine 205 

Ester, formation of an, by replace- 
ment of a metal in a salt 122 

Ester, formation of an, from an 

acid chloride and an alcohol. .55, 104 
Ester, formation of an, from an al- 
cohol and an acid 54, 106, 191 

Ester, formation of an, from an 

alcohol and an acid anhydride. . 137 
Ester, hydrolysis of an. . . 106, 108, 206 

, ortho (reference) 94 

Esterification, by addition of an 

acid to an olefine 205 

Esterification, by means of the alco- 
hol and acid 106, 191 

Ethene, see Ethylene. 

Ether for drying apparatus 15 

, distillation of 70, 161 

, drying 69 

extraction 74 

Ethyl acetate, hydrolysis of 106 



328 



GENERAL INDEX 



Ethyl acetate, preparation of 106 

Ethylamine hydrochloride, in test. 121 
Ethyl ammonium chloride, in test 121 

Ethylbenzene, preparation of 141 

Ethylene, chemical properties. . . 44, 48 
, preparation from alcohol and 

phosphoric acid 40 

Ethylene, preparation from alcohol 

and phosphorus pentoxide 48 

Ethylene dibromide, preparation of 40 

, properties of 45 

Ethyl iodide, preparation of 35 

, properties 38 

isocyanate, formation and prop- 
erties 122 

Extraction with ether 74 

Eye, alkali in 6 



Fehling's solution, reduction of, 

with aldehydes 91, 182 

Fehling's solution, reduction of, 

with sugars 127 

Filter, fluted 128 

, hardened 1 70 

Fire, in case of 6 

extinguisher 6 

Fittig's synthesis of an aromatic 

hydrocarbon 141 

Flasks, Claiscn 76 

, distilling 1 1 

, Erlenmeyer 13, 14 

, Ladenburg 11,22 

Fluorescein, formation of 171 

Fluted filter 128 

Formaldehyde reactions 96 

, resorcinol test 96 

Fractionation apparatus or column 25 

Friedel-Crafts' reaction 144 

Fuchsine-sulfurous acid reagent for 

aldehydes 92, 182 

Funnel, Babo 159 

, Buchner 51, 52 

, dropping 36 

, hot water 128 

, separatory, Squibb's 36 

, , globe-shaped 36 

Furfural test, for pentoses 132 



Gallic acid, ferric chloride test. ... 178 

Gas purifying apparatus 228 

Gelatine, precipitation with tannin 193 

Glass tubing, bending 28 

Glycine, preparation of 1 24 

Glycocoll, preparation of 124 

Grades, laboratory 2 

Grease for stop-cocks 229 

Grignard's reaction 69 

Guard tube, in organic combustions 245 

H 

Halogens, detection with sodium 

decomposition 112 

Halogens, test for with "alcoholic 

potash," etc 38, 150 

Hardened filter paper 170 

Helianthine 171 

Heterocycles, nitrogen 2T3 

Hexamethylenetetramine, prepara- 
tion of 96 

Hippuric acid, for glycocoll experi- 
ment 1 24 

Historical introduction for the de- 
termination of carbon and hy- 
drogen 217 

Historical introduction for the de- 
termination of nitrogen 269 

Hydrocarbon, paraffin; properties 32 

Hydrocinnamic acid, preparation of 184 

Hydrogen, determination of 217 

, in organic substances, test for. 30 

chloride, preparation of 195, 198 

Hydrolysis of butter 108 

ethyl acetate 106 

hippuric acid 124 

isobornylacetate 206 

lecithin no 

methylal 94 

Hydroxylamine hydrochloride, for 

preparing an oxime 100 

, cuprous chloride 50 



Ink 193 

Isoborneol, preparation of 206 

Isobornylacetate, preparation of . . 205 



GENERAL INDEX 



329 



Ketone, reduction to secondary al- 
cohol 73 



I actose, oxidation to mucic acid ... 134 

Lead peroxide, for organic com- 
bustions 265 

Lecithin, from egg-yolk no 

Liquid crystals 67 

</-Limonene-dihydrochloride, prep- 
aration of 195 

List of apparatus for general or- 
ganic chemistry 312 

List of apparatus for the determina- 
tion of carbon and hydrogen. ... 223 

List of apparatus for the determina- 
tion of nitrogen 271 

List of chemicals for the determina- 
tion of carbon and hydrogen ... 224 

List of chemicals for the determina- 
tion of nitrogen 272 

List of chemicals for laboratory ex- 
periments, "long" course 315 

List of chemicals for laboratory ex- 
periments, " short " course 321 

Logarithms, table of 308 

M 

Magnesium for Grignard's reaction 71 
Manometer, for distillation in 

vacua 80 

Manometer, for nitrogen combus- 
tion 281 

Melting-point, apparatus 58 

, bath for high temperatures. ... 66 

, changes in 66 

, determination of 58 

, substances for standardizing 

thermometer 63 

, Thiele apparatus 64 

, tubes for 60 

/-Menthone, preparation of 99 

oxime, preparation of 100 

Mercury, purification of 81 

Methane, from chloroform 31 

Method of running blank determi- 
nations 246 



Methylal, hydrolysis of 94 

Methylamine formation and prop- 
erties 120 

Methylaniline, in test for 2 -amine . 1 65 
2-Methyl-butanol-2, preparation of 69 
Methylene diethers, hydrolysis of . . 94 
Methyl ester of 3-5-dinitrobenzoic 
acid 55 

isothiocyanate, formation of . . . 123 

mustard oil, formation and prop- 

erties 123 

orange, preparation of 1 70 

phenyl-carbinol, preparation of 73 

phenyl ether 180 

salicylate, preparation of 191 

Michler's ketone, for crystal violet 

171, i7S 
Micro-combustion, for carbon and 

hydrogen 221 

Micro-combustion, for nitrogen. . . 270 

Mucic acid, preparation of 134 

Mustard gas, reference 47 



Nitration of an aromatic hydrocar- 
bon 154 

Nitrobenzene, preparation of 154 

Nitrogen, detection of 112 

, heterocycles 213 

, estimation of, by absolute 

method 269 

Nitrometer 285 

" Nitronation " 155 

Note-books 2 



Oil-baths 79 

, water in 82 

Oil of turpentine, rectification of . . 200 

wintergreen, preparation of. . 191 

Olefine formation 40, 48, 202 

Ortho-ester, references 94 

Oxidation of an acetylene (" triple") 

bond 50 

Oxidation of a i -alcohol to an alde- 
hyde 54, 83, 85 

Oxidation of a 2-alcohol to a ke- 
tone 99 



330 



GENERAL INDEX 



Oxidation of a hydrocarbon 210 

side chain 189 

sugar 134 

an olefine "double" bond. . 44, 48 

with concentrated nitric acid. . . 208 

dilute nitric acid 134 

potassium permanganate 

44, 48, 50 

Oxidation with potassium perman- 
ganate in neutral solution 189 

with chromic acid. 54, 83, 85, 99, 210 

Oxime formation too 

Oxygen, for the determination of 

carbon and hydrogen 225 



Palladious chloride solution 245 

Pentoses, furfural test 132 

Permanganate oxidation in neutral 

solution 189 

Phenol, preparation of 177 

, reactions of 178 

Phenolphthalein, formation of 171 

Phenylglucosazone, preparation of. 127 
Phenylhydrazine, for osazone for- 
mation 127 

, for hydrazone formation 182 

Phenylpropionic acid 184 

Phosphorus, detection of 112 

Pinene, tests for "double" bond in . 45,48 
, purification of, for fiinenehydro- 

chloride 200 

Pinenehydrochloride, preparation 

of , 198 

Polymerization of acetaldehyde ... 92 

formaldehyde 96 

Porous tiling, to prevent bumping. 19 
Potassium hydroxide, cutting sticks 

of 3 

Pre-heater, for organic combus- 
tion 228 

Preparations, collection of liquid. . 4 

, labeling i 

' notes on i 

Pyridine, reactions of 213 

Q 

Quinojine, reactions of 213 



Rape-seed oil, for oil-bath 79 

, water in 82 

Reduction of a halogen derivative. 31 

ketone to a 2-alcohol.. . . 73 

an aromatic nitro-compound. 157 

olefine bond 184 

with sodium amalgam and water 184 

sodium and alcohol 37 

tin and hydrochloric acid. . . 157 

zinc-copper couple 31 

Reflux condenser 26 

Resin formation of aldehydes 92 

Resorcinol, ferric chloride test 178 

, for fluorescein formation 171 

, in test for formaldehyde 96 

Rubber stoppers, boring holes in . . 40 
, molded 3 



"Salting out" of a dye 175 

liquid . .' 160 

Sandmeyer reaction 187 

Saponification, see Hydrolysis. 

Schiff's aldehyde test 92, 182 

Sealed bottles, method of opening 33 

Sealing tubes, directions for 117 

Separatory funnel, globe-shaped. . . 36 

, Squibb's 36 

Silver-mirror test for aldehydes. 91, 182 
Soda lime for absorbing carbon 

dioxide in organic combustions 243 
Sodium amalgam, preparation of. . 184 

benzene sulfonate, preparation 

of 152 

Sodium, "bird-shot" 141 

bisulfite, reagent for aldehydes, 

etc 98 

Sodium bisulfite, preparation of 

reagent 98 

Sodium bisulfite, for removing 

stains of manganese dioxide 190 

Sodium hydroxide, cutting sticks of 3 

residues, treatment of . . . .5, 69, 143 

Starch-potassium iodide paper 187 

Steam distillation 158 

Stem correction for thermometers.. 8, 20 



GENERAL INDEX 



331 



Still-head 25 

Stop-cock for" equalizing pressures 

above and below it 278 

grease 229 

Stop-cocks, removing "frozen".. . 4 
Stoppers, glass, removing 4 

rubber, boring holes in 40 

, molded 3 

Suberite ring 141 

Sublimation, method of 211 

Sucrose, hydrolysis of 127 

Suction nitration of small quanti- 
ties 56 

with Buclmer funnel 51-2 

Sugar, hydrolysis of cane 127 

Sulfanilic acid, preparation of 167 

Sulfonation of an aromatic amine. . 167 

hydrocarbon 152 

Sulfur, detection of 112 



Table of atomic weights 

Inside back cover 

corrections for barometer. . . 300 

logarithms and a n t i 1 o g a- 

rithms 308 

vapor pressure of water. . . . 301 

weight of i cc. of nitrogen at 

different temperatures and 

pressures 303 

Tannic acid 193 

Tannin, ink 193 

, reactions 193 

Thermometer, short scale 8 

, standardization of, for b. -p. ... 7, 20 

, m.-p 63, 64 

, stem connection 8, 20 



^Tohmitrile, preparation of 187 

j^-Tolyl cyanide, preparation of . . . 187 
Topical outline, for carbon and 

hydrogen 224 

, for nitrogen 273 

Tra ns- 1 . 8-dichlor- terpane, prepara- 
tion of 195 

Triphenylmethyl, formation of. ... 147 

Triphenyl-methyl-peroxide 147 

U 

Urotropine, see Hexamethylenete- 
tramine 96 



Vacuum desiccator 87 

distillation 76 

valve 78 

W 

Water, vapor pressure of (table).. . 301 

Weighing liquids 267 

the absorption bottles 248 

substance for carbon and hy- 
drogen 250 

, nitrogen 292 

Woulff bottle 198 



Yield, notes on i 

, theoretical i 

, practical i 



Zinc-copper couple 31 




Wiley Special Subject Catalogues 

For convenience a list of the Wiley Special Subject 
Catalogues, envelope size, has been printed. These 
are arranged in groups each catalogue having a key 
symbol. (See special Subject List Below). To 
obtain any of these catalogues, send a postal using 
the key symbols of the Catalogues desired. 



1 Agriculture. Animal Husbandry. Dairying. Industrial 
Canning and Preserving. 

2 Architecture. Building. Masonry. 

Business Administration and Management. Law. 

Industrial Processes: Canning and Preserving; Oil and Gas 
Production; Paint; Printing; Sugar Manufacture; Textile. 

CHEMISTRY 
4a General; Analytical, Qualitative and Quantitative; Inorganic; 

Organic. 
4b Electro- and Physical; Food and Water; Industrial; Medical 

and Pharmaceutical; Sugar. 

CIVIL ENGINEERING 

5a Unclassified and Structural Engineering. 

5b Materials and Mechanics of Construction, including; Cement 
and Concrete; Excavation and Earthwork; Foundations; 
Masonry. 

5c Railroads; Surveying. 

5d Dams; Hydraulic Engineering; Pumping and Hydraulics; Irri- 
gation Engineering; River and Harbor Engineering; Water 
Supply. 

(Over) 



CIVIL 

Be Highways; Municipal 'Engineering; Sanitary Engineering; 
Water Supply. Forestry. Horticulture, Botany and 
Landscape Gardening. 



6 Design. Decoration. Drawing: General; Descriptive 
Geometry; Kinematics; Mechanical. 

ELECTRICAL ENGINEERING PHYSICS 
7 General and Unclassified; Batteries; Central Station Practice; 
Distribution and Transmission; Dynamo-Electro Machinery; 
Electro-Chemistry and Metallurgy; Measuring Instruments 
and Miscellaneous Apparatus. 



8 Astronomy. Meteorology. Explosives. Marine and 
Naval Engineering. Military. Miscellaneous Books. 

MATHEMATICS 

9 General; Algebra; Analytic and Plane Geometry; Calculus; 
Trigonometry; Vector Analysis. 

MECHANICAL ENGINEERING 

lOa General and Unclassified; Foundry Practice; Shop Practice. 
lOb Gas Power and Internal Combustion Engines; Heating and 

Ventilation; Refrigeration. 
V 10c Machine Design and Mechanism; Power Transmission; Steam 

Power and Power Plants; Thermodynamics and Heat Power. 
11 Mechanics. ___ . 

12 Medicine. Pharmacy. Medical and Pharmaceutical Chem- 
istry. Sanitary Science and Engineering. Bacteriology and 
Biology. 

MINING ENGINEERING 

13 General; Assaying; Excavation, Earthwork, Tunneling, Etc.; 
Explosives; Geology; Metallurgy; Mineralogy; Prospecting; 
Ventilation. 



INTERNATIONAL ATOMIC WEIGHTS, 1920. 



Atomic 

Symbol, weight. 

Aluminium Al 27.1 

Antimony Sb 1 20 2 

Argon A 39 9 

Arsenic As 74 96 

Barium Ba 137-37 

Bismuth Bi 208 . o 

Boron B 10 9 

Bromine Br 79 92 

Cadmium Cd 112 .40 

Caesium Cs 132 .81 

Calcium Ca 40 07 

Carbon C 12. cos 

Cerium Ce 140 . 25 

Chlorine Cl 35 46 

Chromium Cr 520 

Cobalt C 58.97 

Columbium 93 . i 

Copper Cu 63.57 

Dysprosium Dy 162 . 5 

Erbium Er 167 7 

Europium Eu 152.0 

Fluorine F 19 o 

Gadolinium Gd 157 .3 

Gallium Ga 70.1 

Germanium Ge 725 

Glucinum Gl 91 

Gold Au 197 2 

Helium He 4 oo 

Ilolmium Ho 163 5 

Hydrogen H i . 008 

Indium In 114.8 

Iodine I 126.92 

Indium Ir 193 . i 

Iron Fe 55.84 

Krypton Kr 82 . 92 

Lanthanum La 139.0 

Lead Pb 207 . 20 

Lithium Li 6 .94 

Lutecium Lu 175 .o 

Magnesium Mg 24-32 

Manganese Mn 54 - 93 

Mercury Hg 200 . 6 

Molybdenum Mo 96.0 



Atomic 

Symbol, weight. 

Neodymium Nd . 144 . 3 

Neon Ne * 20 . 2 

Nickel Ni 58.68 

Niton (radium 

emanation) Nt 222.4 

Nitrogen N 14.008 

Osmium Os 190.9 

Oxygen O 16.00 

Palladium Pd 106 . 7 

Phosphorus P 31 .04 

Platinum Pt 195 . 2 

Potassium K 39 . 10 

Praseodymium ...... Pr 1 40 . 9 

Radium .'. Ia 226.0 

Rhodium Rh 102 .9 

Rubidium Rb 85.45 

Ruthenium Ru 101 . 7 

Samarium Sa 1 50 4 

Scandium Sc 44 . i 

Selenium Se 79 . 2 

Silicon Si 28.3 

Silver Ag 107.88 

Sodium Na 23 .00 

Strontium Sr 87 . 63 

Sulfur S 32.06 

Tantalum Ta 181.5 

Tellurium Te 127.5 

Terbium Tb 159.2 

Thallium Tl 204.0 

Thorium Th 232 15 

Thulium Tm 168.5 

Tin Sn 118.7 

Titanium Ti 48.1 

Tungsten W 184.0 

Uranium U 238 . 2 

Vanadium V 51.0 

Xenon Xe 130.2 

Ytterbium 

(Neoytterbium) . . Yb 173.5 

Yttrium Yt 89.33 

Zinc Zn 65.37 

Zirconium Zr 90 .6