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Full text of "The alkylation of benzene, toluene and naphthalene and the chorlination of acetylene.."

THE ALZYLATIOIJ OF BaiJZSWfi. TOLUfillE Ai^D NAPHTHALENE 
AIJD THE GHLOHIIJATION OF ACETYLENE 



DISSERTATION 

Submitted to the Board of University Studies of 
The Johns Hopkins University in Conformity 
with ii:equirements for the Legree of 
Loctor of i-hilosophy 



by 
Thomas Llorris Berry 



BALTIMOiffi 
JUNE 1923 



\^^ 



oils" 



TABLE OF COlJTEiJTS 

Acknowledgement 

PAHT I. 
The Alkylation of Benzene, Toluene and ivaphthalene 

Introduction 1 

The Present Investigation 2 

Apparatus - Fig. I 3 

The Ethylation of Benzene 4 

Hatio of C5E5 to AIGI3 5 

Examination of the Two Layers 7 

Fig. 2 

Ethylation of Toluene 16 

Ethylation of Brom Benzene 17 

Propylene and Benzene 19 

Propylene and Toluene 33 

Propylene and Naphthalene 35 

Tetrahydro Benzene and Benzene 35 

Summary 38 

PAHT II. 
The Chlorination of Acetylene 

Introduction 40 

Experimental 40 

Conclusions 50 

Biography 51 



ACO0WL2DGE:,:ii:NT 

The author welcomes this opportunity to express his 
deepest sense of gratitude to Doctor lieid, under whose 
direction the first part of this work was done, and to 
Doctors Prazer, Patrick, Lovelace and Thornton for the in- 
spiration received in the lecture room and laboratories. 

Appreciation is also extended to the authorities of 
The Chemical .Varfare Service for permission to publish the 
work on the chlorination of acetylene, which work was done 
at idg-ewood Arsenal. 



TH3 ALETLATION OF B3NZSIIE, TOLUENE AUD NAPHTHALENE. 

Friedel and Crafts and later workers have shown that 
benzene may he alkylated by treating it with an alky^ halide 
in the presence of anhydrous aliuninum chloride - 

RCl ^ C6H6 ^1^1_3> C6H5R -»- HCl 

Balsohn-'- in preparing ethyl benzene modified the Friedel 
and Crafts reaction slightly. Instead of using ethyl chloride, 
he used ethylene and hydrochloric acid in proportions to give 
ethyl chloride - 

CgH^ -f- HCl > CgHgCl 

Since ethyl chloride and benzene react in the presence of alum- 
inum chloride to liberate hydrochloric acid, the total amount 
of hydrochloric acid required in comparison with that of ethy- 
lene is very small since it undergoes a cyclic process 
C2H4 4- HCl > CgHgCl 

HCl -H C6H5C2H5 ; 
in fact Balsohn later found that even traces of water vapor 
in the ethylene used were sufficient, on reacting with the 
aluminum chloride, to furnish the required amount of hydro- 
chloric acid. 

Balsohn's method consisted in bubbling ethylene through 

1. Bull. SOG. Chim. (2) 31, 539 (1879). 



-2- 

a mixture of benzone and aluminum chloride at 70°- 90° C. 
Under these conditions ethylation takes place very slowly; 
consequently the practical importance of the reaction was 
at that time not realized. 

According to McDaniels-'- 1 volume of benzene at 80°C. 
dissolves two volumes of ethylene. Since this solubility is 
small it is important that the benzene be saturated continu- 
ously with ethylene if the best results are desired. This 
point was recognized by Milligan and Reid^ who used high speed 
stirring to maintain a condition of saturation; as a result 
they found that the obscure and apparently unimportant method 
of Balsohn was, in reality, a very practical one - a reaction 
which when performed with the aid of high speed stirring, far 
outrivaled the usual method in which a previously prepared 
alkyl chloride is employed. 

TH3 PRESENT INVESTIGATION. 

1. To study more thoroughly certain features of the 
Friedel and Crafts reaction. 

2. To apply the method of Balsohn in the alkylation of 
Benzene, Naphthalene and Toluene, using high speed stirring. 

3. To study the chlorination of acetylene, using 
stirrin.Dr. 



1. J. Phys. Chera. 15, 605 

2. J. Am. Chem. Soc. 44. 206 



-3- 

APPARATU3 . 

The stirrer as is shovra in Figure I consists of a disc 
two inches in diameter and three sixteenths of an inch thick 
with holes three sixtyfourth of an inch in diameter bored 
radially aroiind its periphery and terminating inside of a 
small cone at the bottom of the disc. The disc is screwed 
onto a tool-steel shaft which is connected by means of belts 
and an intermediate pxilley to a 1700 R.P.M. motor. /Vith the 
size of pulleys which were used speeds as high as 13,000 R.P.M. 
could be obtained. The gas to be used was, after preliminary 
drying and purification, introduced by an inlet tube ending 
just Tinder the cone and thrown out through the small holes by 
the centrifugal force of the rapidly rotating disc. A rather 
closely fitting iron tube was placed around the stirrer shaft 
and connected by suitable means to the frame of the stirrer. 
This tube passed through the rubber stopper of the reaction 
bottle and dipped below the surface of the liquid contained 
therein; in this way a perfectly gas-tight reaction chamber 
was obtained. Baffle plates were used to decrease the gyra- 
tory motion of the liquid. 

A condenser was attached at one end by means of an adapter 
to the reaction bottle, while the other end was connected to 
a receiver for unused gas. 



THE STHYIATIOK OF BJCUZENS. 

Tha ethylene used was of commercial variety but of a very 
high grade of purity. It was first passed through a gas meter. 
The difference between the amount of gas as represented by the 
gas meter and the amount of recovered gas was taken as the 
amount which had reacted. After passing through the gas meter, 
the ethylene was purified and dryed. by passing through two 
gas wash-bottles, one containing pyrogallic acid and the other 
sxilphuric acid respectively; and then through two drying 
towers filled with soda lime and another containg phosphoric 
anhydride. 

The gas was passed into the benzene-aluminum chloride 
mixture at such a rate as to allow only an occasional bubble 
to escape. This was found to be the method conducive to the 
best resiilts, since if the amount of escaping gas is large, it 
carries appreciably quantities of hydrochloric acid along with 
it and the reaction slows down to a very marked degree. In 
some cases it was possible to restore the original reactivity 
by passing in small quantities of dry hydrochloric acid along 
with the ethylene. 

In all of the experiments, the temperature was held at 
approximately 70°. It was found that the change of tempera- 
ture coefficient of the reaction within the interval 60°-90°C. 
is approximately zero. 



Throughout the work it was found that an incubation 
period of about twenty minutes before the passage of the 
ethylene, favored the reaction. 

Experience has shown that at any given Instant during 
the course of a reaction, a maximum rate of absorption of gas 
under the prevailing conditions can be obtained, only with 
one particular rate of stirring. If the rate of stirring be 
reduced below this point, a reduction in the rate of gas 
supply must be made; while on the other hand, if the rate of 
stirring is increased, a corresponding escape of gas takes 
place with the consequent loss of hydrochloric acid, and, as 
a resiilt the reaction slows down to a very marked degree. 
The rates of stirring ranged between 8,000 and 10,000 E.P.LI. 

RATIO OF C5H5 TO AICI3 

It was desirable to know the relative proportions of 
benzene and aliuninum chloride which would afford a maximum 
rate of reaction. It is quite conceivable that if this ratio 
be either very large or very small a poor rate of reactions 
will be obtained. The Inclination is to use a large amount 
of catalyst with the hope of insuring a good rate of reaction; 
it has however been fo\md that an excess of aluminum chloride 
is Just as detrimental to the rate of reaction as an insuf- 
ficiency. The aluminiun chloride used in all of the experi- 
ments in one set was from the same lot. 



-6- 



Slnoe the usual course of a catalytic reaction is to in- 
crease up to a maximum and then decrease, a comparison of 
results can be obtained only by counting time from the in- 
stant at which the introduction of the ethylene is begun, 
since the rate of increase of reaction rate varies in the 
different experiments. In table I the rates of absorption 
for a period of 134 minutes after the introduction of the 
ethylene are listed for five different experiments in which 
varying relative amounts of aluminum chloride and benzene 
were used. 

TABLE I 

Ext. 



Molal I 
AICI3 


latio 
C6H6 


Z. C2H4 
Absorbed 


Time 


Average Hate of 

Absorption 
cc. CgH^/Mol CgHg/LIin 




8.5 


58.6 


134 


114 




10 


60.9 


134 


120 




13 


138.5 


134 


200 




22 


104.4 


134 


133 




44 


4.8 


134 


10 



It thus appears that better results are obtained when the 
ratio of aluminum chloride to benzene lies between 1 : 13 and 
1 : 22 . Ratios greater than 1 : 13 give poorer results while 
a ratio as small as 1 : 44 gives practically no results. 



-7- 



EXMIIMTION OP THIi TWO LAYERS 



Friedel and Crafts^, Gustavson, Boeaeken and others have 
fotmd that in the Friedel and Crafts reaction, there are always 
two layers formed. A clear upper layer and a dark "brown, very 
viscous lower layer. They state that the upper layer contains 
mostly benzene and the low boiling products, i.e. the lower 
substituted benzenes, while the lower layer contains materials 
boiling at much higher temperatures. An explanation for this 
phenomenon makes its appearance on consideration of the various 
theories which have been proposed to explain the mechanism of 
the Friedel and Crafts reaction. Friedel and Crafts own theory 
was, that the aluminum chloride used combines with the benzene 
to form a compound CgH5.Al2Cl5 which later reacts with the alkyl 
chloride giving hydrochloric acid and a substituted benzene 

CgHgAlgClg + RCl -> CgHgR -V HCl 

This theory was later abandoned for the theory proposed by 
Gustavson*^ who attributed the condensation to the formation 
of addition products of aluminum chloride with three molecules 
of benzene AICI3.3 CgHg; products which have been isolated and 
analyzed. These addition products are attacked very easily by 



1. Ann. Chim. Phys. 6, (1), 449 

2. B. 12, 853; 13, 157; 16, 784; 33, 767. 



-8- 



alkyl chlorides: 

AICI3.3 C5H5 + 3 RCl -> 3 HCl -V AlClg.SCCgHsR) 

AICI3 -+ 3 CgHgE 

Boeseken-^ has shown that Gustavson's intermediate is 
formed only in the presence of traces of moisture. He also 
shows that Gustavson's assiimption, that one mol of AICI3 suf- 
fices for 3 mols of hydrocarbon and three mols of alkyl 
chloride, is not valid in certain cases, since in these one 
mol of AICI3 will condense only one mol of hydrocarhon and 
one mol of alkyl chloride. He contends that the aluminum chlo- 
ride confines with the alkyl halide and has isolated some of 
these compounds 

C5H5COCI.AICI3 -t- C5H5 -^ C5H5COC5H5.AICI3 

Boeseken^ points out that in the formation of homologues 
of "benzene, a very small amount of AICI3 was sufficient to 
cause the reaction of a large amount of alkyl halide. This, 
he explained, was due to the inability of AICI3 to form very 
stable compounds with the reactants. 

All of the theories which have been proposed assume that 



!• Boeseken - A. ch. (G) 14, 467 
E. Boeseken - Rec. Trav. 22, 301 



aluninum chloride forms an addition product with the alky- 
lated benzene. If this be true, then we should expect to 
find at the end of our reaction, the most alkylated benzenes 
in corabination with the aluminum chloride. 

This point was investigated by first separating the two 
layers, as well as possible, by siphoning off the upper layer. 
The two layers were then treated separately with water to de- 
compose the aluininiim chloride complexes. The amounts of these 
complexes, in the upper layer, are very small as is shown by 
treating with water; practically no heat is evolved and only 
very small amounts of aluminum hydroxide precipitate. The 
lov/er layer, on the other hand, contains practically the whole 
of the aluminum chloride used and has to be decomposed extremely 
slowly and with constant cooling. The upper and lower layers 
were fractionated separately through a Vigreux column. It 
was found that the lower layer contained, by far, a higher per- 
centage of the more alkylated benzenes. 

The following ratios will indicate the relative molecu- 
lar amounts of the different ethyl benzenes appearing in the 
upper and lower layers. These calculations were made upon 
the basis of 1000 molecular weights of mono ethyl benzene 
appearing in the upper and lower layers respectively. 



•10- 



Rtm 



4 
12 



Layer 


Mono 


Di 


Tri 


Tetr: 


Upper 
Lower 


1000 
1000 


583 
1943 


122 
698 


47 

199 


Upper 
Lower 


1000 
1000 


588 
325 


354 

354 


177 
177 


Upper 
Lower 


1000 
1000 


94 
354 


42 
125 




Upper 
Lower 




1000 
1000 


5253 
7169 


1128 





3991 



Penta 



26 

302 


32 

151 


59 
1622 


59 
270 


1204 
9018 


1813 
71 



Prom the data given, it is quite apparent that there is 
a marked difference in the composition of the two layers. In 
run #£ the reaction was stopped in its early stage, i.e. after 
considerable quantities of mono- and di-ethyl benzenes had 
been formed. Run #12 was carried much further toward completion 
and as a restilt higher percentages of the more ethylated 
benzenes were obtained. In all of the runs which v/ere made, it 
was observed that an extraordinary high percentage of penta 
ethyl benzene was obtained in the lower layer as compared with 
that in the upper layer. 

In all of the experiments it was observed that the speed 
of the reaction increased up to a maximum, remained constant, 
and then began to decrease. Experiment #13 shows this rather 
clearly. In the following table the rates are given in cc. of 
ethylene absorbed with their respective periods of absorption. 



•11- 





# 13 






Period of 

Absorption 

Min. 




CO 

Ab 


. of C2H4 
sorbed per 

Min. 


72 






190 


30 






770 


20 






1300 


30 






1220 


35 






1350 


15 






1322 


15 






982 


18 






883 



Fig. 2 is a graphic representation of these values. 

The manner in which the benzene was dryed had considerable 
influence on the reaction. Calcium chloride-dryed benzene on 
being stirred with aluminum chloride gave rise to hydrochloric 
acid fumes which hovered above the surface 6f the benzene. 
After the reaction had progressed for some time these fumes 
gradually disappeared. Reactions in which calcivin chloride 
dryed benzene was used appeared to be very sensitive to changes 
in temperature, rate of stirring and loss of hydrochloric 
acid, and further, maintained the maximum rate for only a 






I 200 



1 ZOO 








llOO 




1 000 



900 



0. 



&00 < 
N 



600 <: 



^00 



_ J- 



300 



106/_ 



\ 1-i--:| i 



Time In h^l i nutes 



s 



20 40 60 80 100 120 (40 ISO 180 ^oo zio z^q 



FLq' Z. 



-12- 



short period as compared to sodium-dryed benzene, which did 
not yield white fumes of hydrochloric acid on being stirred 
with alwnintun chloride. 

iixperiment #E gives a fair idea of the rate at which 
benzene can be ethylated. 5.83 mols of benzene were ethy- 
lated with 139 Z. of ethylene, in the presence of 60 g. of 
AlCl-3 over a period of 134 minutes. The average rate of 
ethylatinn being 1034 cc. of ethylene per minute. The above 
amount of ethylene was calculated from the products obtained 
which were - 

123 g. Benzene 
200 g. iithyl benzene 
155 g. Di ethyl benzene 
42 g. Tri ethyl benzene 
18 g. Tetra ethyl benzene 
13.5 g. Penta ethyl benzene 
16 g. Hexa ethyl benzene 

It has been previously stated that the reactions were run 
so as to permit only an occasional bubble of ethylene to escape. 
In this experiment calculation shows that 97 % of the ethylene 
sent into the reaction bottle is present in the distilled 
products. In this experiment 3.85 mols. of benzene, 0.385 mols 
of AICI3 and 14.1 mols of ethylene were made to react over a 
period of 675 minutes. The products obtained were - 



-13- 

l/2 g. Benzene 

4 g. Ethyl benzene 

74i- g. Di ethyl benzene 

305 g. Tri ethyl benzene 

8E g. Tetra ethyl benzene 

31 g. Penta ethyl benzene 

154 g. Hexa ethyl benzene. 

It was not possible to ethylate the benzene directly to 
hexaethyl benzene with the apparatus which was used in this 
work, due to the increase in volume of the liquid mixture 
on ethylati6n. The volume change is about 100 °io for an 
ethylation of about 80 per cent. 

Experiment # 13 is interesting from the standpoint of 
the comparative ease of ethylation of benzene and diethyl 
benzene. A mixture of 2.E4 mols of diethyl benzene and 0,385 
mols of aluminum chloride was ethylated at a rate of 900 cc. 
per minute for 233 minutes. In this experiment benzene and 
aluminum chloride were employed in the ratio of 1 : 5.7 and 
the average rate at which the ethylene reacted for a period 
of the first 134 minutes amounted to 257 cc. per mol of di- 
ethyl benzene per minute. This is a much higher rate than 
would have been obtained had benzene and aluminum chloride 
been used in the above proportions. If diethyl benzene 
ethylates at the same rate as benzene we would have expected 
a lower rate of absorption. It appeared throughout this 
work that alkylated benzenes alkylate with somewhat greater 



-14- 



ease than does benzene; in other words it is harder to sub- 
stitute the first alkyl group into the benzene ring than it 
is to substitute the second alkyl group. This experiment 
was stopped on account of the product solidifying in the re- 
action bottle and consequently preventing further stirring. 
There were obtained on separation - 

447 g. Hexa ethyl benzene 
32 g. Tetra ethyl benzene 
4 g. Penta ethyl benzene 
3 g. Residue 

The amount of ethylene which reacted in this experiment 
represents 822- % of the amount required to convert all of 
the diethyl benzene into hexa ethyl benzene. Of the amount 
of ethylene which reacted 86-2 % was accounted for in the 
hexa ethyl benzene obtained after centrifuging out the in- 
cluded oils. 

In experiment #14, 2.24 mols of tri-ethyl benzene were 
ethylated with 5.03 mols of ethylene; 6.385 mols of AlClg 
were used and the reaction run for a period of 248 mimites. 
The average rate was 240 cc. per minute for the first 134 
minutes as compared with 257 cc. per mol of diethyl benzene 
as was stated in the previous experiment. From these results 
it appears that tri-ethyl benzene can be alkylated at ap- 
proximately the same rate as diethyl benzene but both of 
these at a greater rate than benzene. This reaction was 



-15- 



stopped before the products in the reaction bottle solidi- 
fied. On separation there were obtained - 
345 g. Hexa ethyl benzene 
10 g. Penta etliyl benzene 
70 g. Tetra ethyl benzene 
22 g. Tri ethyl benzene 
The amount of ethylene which reacted corresponded to 72-^ % 
of the amount required to carry all of the tri-ethyl benzene 
to hexa-ethyl benzene; of this amount 8C.1 percent went to 
form hexa-ethyl benzene. 

It was expected that by stirring gaseous ethyl chloride 
into a mixture of benzene and alumintim chloride that the 
ethylation would take place somev^at faster, since a certain 
amount of time must be consumed in its formation from ethy- 
lene and hydrochloric acdi. Commercial ethyl chloride after 
drying was passed into a mixture of benzene and aluminum 
chloride. In this reaction one mol of hydrochloric acid is 
liberated from each mol of ethyl chloride which reacts; con- 
sequently the escaping hydrochloric acid carried large amounts 
of ethyl chloride along with it and as a result a large loss 
was involved. On the whole, this method was very unsatis- 
factory as compared with that in which ethylene was used. 

The reaction between ethylene and benzene in the presence 
of AICI3 is exothermic and a cooling coil was placed aroimfl. 
the reaction bottle vixich was immersed in a water bath; this 
was used in case the mixture got above 70^0. 



•16- 



It was fotmd that the reaction was aided "by allowing 
the temperature to rise, at the "beginning, tmtil gentle re- 
fliLicing was taking place. The refluxing was allowed to con- 
tinue for several minutes, after which the mixture was cooled 
to 700C. Refluxing for short periods of time tended also 
to revive the reaction after it had slowed down. 

Two different boiling points are given in Beilstein for 
Hexa-ethyl Benzene namely 305°C. and 292°C. In this work 
a total of about 1400 grams of hexa- ethyl benzene were pre- 
pared; consequently, it seemed that advantage should be taken 
of this opportunity to obtain its boiling point. After 3 
recrystallizations from hot alcohol, the boiling point as 
determined with a 400 g. sample was found to be 293°C. at 766 

ETHYLATIOII OF TOLUNSKS. 
3.04 mols of toluene were treated with ethylene at a rate 
of 811 cc. per minute for a period of 81 minutes. This re- 
presents a rate of 266 cc. per mol of toluene per minute. 
This is a greater rate of ethylation than could be obtained 
with benzene. On fractionation of the product under ordinary 
pressure the following fractions were obtained: 



Up to 120° C. 


= 


45 g, 


120 - 145° 


z 


42 g, 


145 - 160° 


= 


47 g, 


160 - 164° 


, 


74 g, 


164 - 171° 


- 


33 g. 



-17- 



- mostly toluene 

- a mixture of dimethyl and ethyl 
benzenes 

- ortho- and meta-mGthyl ethyl 
benzenes 

- p. ethyl methyl benzene 

1.3,5 trimethyl benzene and 
1.2.4 trimethyl benzene 

171 - 198° = 28 g. 1.2.3 trimethyl benzene and 

1.2.3.5 and 1.2.4.5 metaethyl dimethyl benzene 

198 - 203° 2 32 g. 3.5 diethyl -1-ipethyl benzene. This 

fraction had an intensive blue fluorescence. 

203 - 207 = 33 g. 1.2.3.4 tetra methyl benzene 

5 g. Residue. 

The ethyl-methyl benzenes have been prepared by the 

Pettig synthesis-^. 

ETHYLATION 0? BROM BSIIZSITS 
2.83 mols of Brom Benzene were ethylated at a rate of 
70 cc. per mol of brombenzene per minute for a period of 
345 minutes using 0.375 mols of aluminum chloride. Toli^ene, 
on the other hand , was etlaylated at a rate of 266 cc. per 
minute per mol of toluene under nearly the same conditions. 



1. Glaus - B. 18, 1121 

vVroblewski - A. 192, 198 
?ittig & Gliazer - A. 136, 312 
Jannasch & Deickmann - B. 2. 1513 



-18- 



It appears that alkyl side chains Increase the rate at 

which the "benzene ring can be alkylated, while halogen 

substituents effect a retardation. Previous workers have 

shown, that AICI3 causes a shifting of halogen atoms in the 

benzene ring. This, as would be expected, took place in the 

ethylation of brombenzene. On fractionation of the product 

we obtained the following fractions: 

Up to 140° C. - 15 g. - a mixture of benzene and ethyl- 
benzene 

140 - 180" r 135 g. Sthyl- & DlEthyl-Eenzene 

180 - 204° z 47 g. - 2 brom-1-ethyl benzene 

204 - £15° = 39 g. - 4 brom-1-ethyl benzene 

215 -221' z 45 g. - Triethyl benzene and dibrom benzene 

221 - 240° - 35 g. Brom-diethyl benzenes. 

240 - 250" r 35 g. Decomposed with liberation of 

hydrobromic acid. 

Residue = 85 g. - Tar 



-19- 



PROPYIENE AND BSRZERS 

Gustavson-^ has shown, that when normal propyl bromide 
and isopropyl "bromide react with "benzene in the presence 
of alumintan chloride the same compound, namely isopropyl 
"benzene, is o"btained. It is evident from this that the 
alximinum chloride causes a transformation of the one form 

of propyl "bromide into the other. 

2 
Kekule and SchrOtter have shown that normal propyl 

"bromide under the influence of AICI3 splits off HBr and re- 
arrangement is brought about giving isopropyl bromide: 

H H H H Br H 

H-C-C-C-Br J^±ll^ H-C-C-C-H 
III III 

H H H H H H 

This action is a minimum at 0°C. 

From 60 g. of propyl bromide and 80 g. of Benzene, 

Gustavson obtained 20 g. of isopropyl benzene, a yield of 34%. 

Jacobsen^ prepared isopropyl benzene by the ?ittig 

method using 100 g. of isopropyl iodide and an excess of 

benzene. After a reaction period of 4 days he obtained 5 g. 
of isopropyl benzene, a yield of 7%. 



1. B. n, 1251 

2. Bl. (4) 3, 726 

3. B. 8. 126U 



■20- 



Liebman-^ prepared isopropyl benzene from benzal 
chloride and zinc methyl 

LI CU3 , . /CH, 

"^ CI CH3 ^ ^ ^^^3 

Since isopropyl benzene can be prepared only very slowly 
by the above methods, which furthermore afford very low yields, 
it was hoped that the reaction between propylene and benzene 
in the presence of AICI3 would prove a better means for its 
preparation. 

Propylene was generated from isopropyl alcohol by drop- 
pinsr it upon raeta phosphoric acid at a temperature of 500°- 
700° C. This method, although it yields propylene of a very 
high degree of purity, is undesirable from the standpoint of 
the destructive action of phosphoric acid upon the glass 
reaction vessel at this temperatiire. The action was such 
as to gradually eat away the bottom of a pyrex flask in the 
course of ten hours under running conditions. 

A slightly less pure grade of propylene (less reactive) 
can be obtained more readily, and in larger amounts, by pass- 
ing isopropyl alcohol vapor over pumice impregnated with 
■^^2^3 ^^^ ^Q^^ ^"t a temperature of about 600°C. The pumice 

1. Liebman - B. 13. 46 



•21- 



so impregnated may be naed for a period of 6 - 8 months 
before yielding an undesirable grade of propylene. The 
propylene was collected in a tank over water and after 
passage through a gas-meter was purified as in the case of 
ethylene. 

The rate of reaction between propylene and the benzene- 
altuninum chloride mixture was much slower than when ethylena 
was used. This might be explained as being due to the in- 
crease in weight of the isopropyl radical over that of the 
ethyl radical. 

In experiment #18, 15 mols of benzene were treated with 
propylene at a rate of 122 cc. per minute or 8 cc. per minute 
per mol of benzene for a period of 1770 minutes in the presencf 
of 1.1 mols of AICI3. This is a rate of about l/25 that at 
wliich it was possible to ethylate benzene. The two layers 
on fractionation gave the following products: 





Top Layer 


Bottom Layer 


35 g. 


up to 75°(b.p. 28°) 




188 g. 


Benzene 


54 g. Benzene 


550 g. 


Mono Isopropyl Benzene 


82 g. 135 - 155° 


369 g. 


Di Isopropyl Benzene 


32 g. 200 - 22C° 


62 g. 


Tri 


28i g. 220- 255° 


15 g. 


Tetra " 


16 g. 225 - 285° 


15 g. 


Residue 


75 g. Residue 



The molal relationship of these products existing in the two 



-22- 



layers, calculated upon the "basis of 1000 mols of inono- 
isopropyl benzene existing in each layer, is - 

Mono Di Tri Tetra 
Top 1000 : 497 : 66 : 13 
Bottom 1000 : ^85 : EOO : 100 

From this relationship it is apparent, as was the case 
with the ethyl benzenes that the bottom layer is relatively 
richer in the more highly substituted benzenes than is the 
upper layer. The crude product in this experiment differs 
from that obtained in the ethylation of benzene in that a 
fraction boiling below 75° was obtained and that further, 
the bottom layer always contained a high percentage of tar. 
The isopropyl benzenes which appear in the literature at the 
present time are - mono-, ortho- and meta-di and 1:3:5 tri- 
isopropyl benzene. By a study of the temperature intervals 
existing between the boiling points of the ethyl benzenes a 
very good idea was obtained as to the temperature limits 
between which the higher substituted isopropyl benzene fractions 
should be taken; after the boiling points of several of these 
higher products had been obtained it was apparent that the 
fractions had been cut within the proper ranges. 

In experiment #21, 14 mols of benzene were treated with 
100 cc. of propylene per minute (7 cc. per min. per mol of 
benzene) for a period of 2551 minutes in the presence of 1.1 
mols of illClg. The crude prodilcts yielded - 



■83- 



Upper Layer 




Lower Layer 


22 g. up to 75 




2 


g- 


252 g. Benzene 




53 


g. 


720 g. Liono Isopropyl Bnezene 


119 


g- 


293 g. Di 


" 


30 


g. 


29 g. Tri 


11 


20 


g. 


Tetra " 


ti 


5 


g- 


16 g. rlesidue 


Molal Ratio 


77 


g* 


Upper Layer 


1000 : 299 


23 


: _ 


Lower Layer 


1000 : 180 


100 


: 5 



It was noted throughout this v/ork that the complexes 
of AlClg with the isopropyl benzenes were decomposed more 
slowly "by water than were the complexes "between AICI3 and 
the ethyl "benzenes. 

It "became the additional o"bject of this work at this 
point to prepare some of the higher isopropyl benzenes. It 
is apparent from the data so far presented that mono- and 
di- isopropyl benzene may be prepared in large amoxmts by the 
reaction between benzene and propylene. After several attempts 
to carry the reaction to such a stage that the products 
would consist largely of the higher alkylated benzenes it 
was found that time was saved by first isolating the lower 
products and then retreating these with propylene in the 



•84- 



presence of AlClr^. It was also interestiriR: to find out 
whether or not the isopropyl benzenes and propylene react 
with greater ease than benzene and propylene. 

In experiment #23, 3 mols of mono isopropyl benzene wer( 
treated with 42 cc. of propylene per minute (14 cc. per mol 
of mono isopropyl benzene per minute) for a period of 1655 
minutes. Prom these results it is again apparent that an 
alkyl benzene may be alkylated with greater ease than benzene 
The two layers on fractionation yielded the following: 



Top Layer 


Bottom Layer 


10 g. 


up to 75° 




7 g. 


Benzene 

I.iono Isopropyl Benzene 




2t g. 


ig. 


20 g. 


Di " " 


ig. 


H9i g. 


Tri 


33 g. 


12 g. 


Tetra " " 


7 g. 


2 g. 


7/hite oolid 




10 g. 


Residue 


5 g. 



The percentage of each product occurring in each layer 



is 





Mono 


Di 


Tri 


Tetra 


Top 


0.73 % 


4.38% 


93.47c 


1.85% 


Bottom 


E.04 


1.5 


82.1 


14.3 



In this experiment a total of 452^- grams of the tri iso- 
propyl benzene was prepared. This product contains about 
92% of the propylene used in the experiment. 



■26- 



In experiment #22, 10.6 mols of mono- iijopropyl benzene 
were treated with propylene at a rate of 16 cc. per mol of 
propylene per minute (total of 170 cc. per minute) for a 
period of 1388 minutes in the presence of 60 g. of AICI3. 
The total products from the two layers were fractionated and 
refractionated several times to gain an idea of the relative 
isomeric yields. The fractions obtained were: 
17 g. up to 75° at 766 mm. 

20 g. Benzene 75 - 90 ° 

i g. 90 - 152 

220 g. Llono 152 - 156 (B.P. 152 - 154) 
25 g. Mono- Di- 156 - 201 
33 g. Mono- Di 201 - 203j 

203 J - 204i (B.P. 204) 
2044- - 205-1- 
206 - 206V 
206;^.: - 208^ 

208^- - 209V (B.P. 209) 
212 - 215 
215 - 220 
220 - 225 
225 - 230 
230 - 233 
256 g. 1.3.5 Tri 233^-234'; (B.P. 234) 
56 g. 2341 - 235V 

46 g. 236V - 236^ 



410 g. 


Mono- Di 


22 g. 




23 g. 




23 g. 




119 g. 


Ortho- D: 


20 g. 




35 g. 




12 g. 




11 g. 




6 g. 





-26- 



47 g. 




236^ - 237^ 


6 g. 




238 - 239 


9 g. 




239 - 24C 


15 g. 




240 - 241 


s g. 




242 - 243 


16 g. 




243 - 246 


61 g. 


above 


246° 



It appears from this data that about 65/o of the di- 
isopropyl benzenes formed is the meta. Of the tri-isopropyl 
benzenes fromed, about lb% is symmetrical tri-isopropyl 
benzene. 

250 g. of 1.3.5 tri-isopropyl benzene was treated with 
56 1. of propylene in the course of 12 hours. This reaction 
went at an exceptionally high rate; it being possible to 
cause an absorption of 80 cc. of propylene per minute. The 
reaction was not allowed to go to completion. On cooling 
the products in the reaction bottle solidified. On purifi- 
cation it was found that a white solid had been formed which 
was identical with the 2 grams of white crystalline compound 
obtained in experiment #23. The fractions obtained from the 
crude material were: 

5 g. 234 - 236 

48 g. 236 - 245 

14 g. 245 - 260 



•27- 



24 g. 260 - 265 

15 g. 265 - 270 

110 g. above 270 

26 g. 'iVhite crystals. 

Several runs were made using tri-isopropyl benzene and 
it was found to be possible to run the reaction until the 
products solidified completely. A total of 65 grams of the 
white crystalline material was prepared. It was centrifuged 
free of included oils and recrystallized several times from 
alcohol. The material crystallized in the form of long white 
needles which had a melting point of 117° and a boiling point 
of 260° at 775 ram. This material was oxidized with a 7/'b 
soli^tion Oi' permanganate on a water bath for one month and an 
acid melting at 282° was obtained. This could have been either 
mellitic acid of m.p. 286° or the dianhydride of 1.2.4.5 tetra 
carboxylic acid of melting point 286° C; hov/ever it would not 
be expected that the anhydride of this acid would be formed 
under the given conditions. 

The silver salt of this acid was prepared and gave an 
analysis 65.42 % Ag, the theoretical for s41ver mellitate 
being 65.82 °lo^ while the theoretical for the silver salt of 
benzene tetra carboxylic acid is 63.32 /b. The boiling point 
of the hydrocarbon (260° at 775 mm.) indicates that it Is 
tetra isopropyl benzene rather than hexa isopropyl benzene 
since its boiling point lies far belov/ that of hexa etiiyl 



-28- 



benzene (294°); also oils boiling above this were obtained 
(E65^° and 270°C.) which are thought to be tetra isopropyl 
benzenes. Mirtirros of oils boiling even higher than 270° 
were obtained but in insufficient quantities for separation. 
The 1.2.4.5 tetra methyl benzene boils below its two isomers, 
it being a solid while the isomers are liquids at room tem- 
perature. The boiling points of the hexa alkyl benzenes in- 
crease with increasing complexity of the alkyl groups as 
would be expected, hexamethyl benzene boiling at 254 ° and 
hexaethyl benzene at 294°; therefore we should expect hexa- 
isopropyl benzene to boil higher than 294°C. A combustion 
was made on this hydrocarbon and the following analysis 
obtained. 



Sample 



Theoretical For 
Hexa Penta Tetra 



% C 87.43 87.18 87.41 87.72 

87.60 



fo H 12.43 12.82 12.59 12.28 

12.61 

Since p. diisopropyl had not been made, considerable 
time v/as spent in trying to locate it within the range of 
the boiling points of the meta and ortho diisopropyl benzenes. 
The attempt to isolate this material failed, however, althoiigh 
it is thought that it boils between 212° and 216° since such 



-29- 



a fraction was obtained which was quite resistant to further 
separation. Hot enough of this fraction was obtained, how- 
ever, to effect an adequate separation. 

An attempt was made to synthesize para diisopropyl 
benzene by means of the Fittig synthesis. 240 grams of iso- 
propyl benzene were brominated with 321 grams of bromine in 
the presence of 30 g. of iodine at 0°C. On fractionation 
of the product there were obtained 290 g. of para brom- 
isopropyl benzene and 40 grams of oriho brom isopropyl benzene. 
Isopropyl chloride was obtained by refluxing isopropyl 
alcohol with an excess of concentrated hydrochloric acid, 
using a Hempel coltunn mounted by a 40" Vigreux column. By 
using this arrangement and carrying on the distillation so 
that the material does not distill above 50° a fairly rapid 
preparation of isopropyl chloride may be obtained. The para 
brom-benzene was mixed with its molecular equivalent of iso- 
propyl chloride and the mixture treated with the calculated 
quantity of sodium. The product on being separated yielded 

75 g. of a fraction 150°-1570c. 

300 g. of an earthy material. 
The fraction 15C°-157° was oxidized with permanganate, and 
benzoic acid of melting point 121°-122° obtained. It is 
evident from this that the bromine of para brom-isopropyl 
benzene was replaced by a hydrogen atom. This evidently 
came about as a result of the splitting off of hydrochloric 



-30- 



aoid from isopropyl chloride which thon reacted with the 
para brom benzene through the agency of the sodium to give 
isopropyl benzene. It was noticed while the reaction was 
tailing place that a gas was being liberated, this gas was 
evidently propylene. 

The earthy material was very light in v/eight, had a 
dark brown color and was insoluble in all of the common 
organic solvents; even on extraction with xylene for several 
days using a Soxlett apparatus nothing dissolved. The 
material burned in a manner much like cork and emitted a 
grayish smoke having a peculiar odor. This material is 
likely a polyphenyl compound. 

Jacobsen-'- states that it is very hard to put even one 
isopropyl group into the benzene ring by the Pittig Synthesis 
since the isopropyl halide is attacked with difficulty by 
sodium. After allowing brombenzene and isopropyl iodide to 
react for four days in the presence of sodium he obtained 

only a 5^i yield. Sprinkmeyer^ tried to prepare ortho iso- 

C ^- 
cymol ^yyj . y, from ortho brom toluol, isopropyl iodide 

f 1 ■" 
and I I sodium but failed to get any of the de- 



I J sodii 

tioweve 



sired product; he was however able to prepare small amoxmts 
of it from ortho bromcumol /■\_-\3,r • ^^'ti^yl iodide and 



sodi\im. 

1.3.5 Triisopropyl benzene has been prepared 3. YhQ 



1. Jacobsen - Ber. 8, 1260 

2. iprinkmeyer - Ber. 34, 195 

3. Comi^t. rend. 140, 940 ; C 1905 (11) 379; 
J. prak. Chem. 2 72.. 57 



-31- 



1.2.4 isomer was obtained as a result of the present work 
by refractionating the triisopropyl benzene fraction a number 
of times in a vacuiim using a pressure regulator. A total 
of 300 grains of this oil was obtained having a boiling point 
of 237°-237i° at 752.5 mm. and 97°- 97';-° under 4 mrn. It was 
oxidized for five days on a v/ater bath by a 7 percent solu- 
tion of permanganate. An acid melting with anhydride for- 
mation at 214° was obtained, this evidently is 1.2.4 benzene 
tri-carboxylic acid. The oil Ijad a specific gravity of 
0.87644 at 0°C. and of 0.85928 at 250c. It had a color of 
+ 18 as determined by the method recommended by the ^Imerican 
Society for Testing Ilaterials using a viscosity of 21.7 
seconds at 100°?. for 30 cc. using a Sabolt Universal Vis- 
cosimeter; 30 cc. of v/ater under the same conditions gave a 
viscosity of 17.4 seconds. The index of refraction was found 
to be 1.4855 at 25°C. The oil gave a flash point of 205°:\ 
and a fire test of 245°i\ 

200 grams of another oil were isolated. This had a 
boiling point of 270°C. at 766 mm. It had a color of -12 
and flash and fire points of 240° and 280°?. respectively. 
The specific gravity was found to be 0.91283 at 0°C. and 
0.89658 at 25°C. Its refractive index at 25°C. was found 
to be 1.5060. Its viscosity as determined with 30 cc. of 
oil was 45.7 seconds at 100°?.; the same amount of water at 
this temperature required 17.4 seconds. This oil was oxidized 



-32- 



with permanganate and an acid having a melting point of 
was obtained. 

About 60 grams of another oil was isolated. It had a 
boiling point of 265V°C. at 755.7 mr.i. and 10Zlr°C. at 4 mm. 
and refractive index 1.49G9. Color -7. 

The fraction boiling belov/ 75° was refractionated and 
fomid to be composed of two substances one boiling at 28°C. 
and t]ie other from 56°- 59°. The latter is likely diiso- 



propyl which has a boiling point of 58°C. The former had a 
specific gravity of 0.70949 at 0°G. 

2.5 dibrom isopropyl benzene was prepared by brominating 
120 grams of isopropyl benzene with 325 grams of bromine in 
the presence of iodine at a lov; temperature. 235 grams of 
a liquid boiling at 258°- 259° and having a refractive index 
of 1.5718 at 25° was obtained. This oil was oxidized with 
permanganate and an acid having a melting point of 151°C. 
was obtained; this is evidently 2.5 dibrom benzoic acid which 
melts at 151°-155°. 



-33- 



PROPYLSNil AlID TOLUSKi: 

Kel"be states that by treating toluene v/ith isopropyl 
iodide in the presence of alvj-ninun chloride meta i30c;>-mol 
is obtained. Flttig attempted to prepare para methyl iso- 
propyl benzene from para broratoluol, isopropyl iodide and 
sodiiun but failed to get the desired product^. However, 
Widman^ prepared it by the Pittig sjmthesis using para- 
brom-isopropyl benzene and methyl iodide. 

7.2 mols of Toluene were made to react with 2-5- mols of 
propylene at a rate of 75 cc. per minute in the presence of 
ICO g. of AlClg. It is to be noted that this reaction goes 
somewhat faster than that between propylene and benzene. 
The product after purification was fractionated into the 
foil owing :- 

5 g. Benzene 
370 g. Toluene 1050-1200 
17 g. Xylene I20O-145O 

25 g. 145°-170° A mixture of trimethyl benzene 
and ortho c:,Tnene 
161 g. 170°-185° of meta isocyraene (175-176) and 

cymene (para methyl isopropyl ben- 
zene) 175°-176° 
60 g. above 185° 
If the fraction 170°- 185° be a mixture of meta-and para- 



1. Ann. 210, 10 

2. iUin. 149, 337 

3. Ber. 24. 450 



-34- 



methyl isopropyl benzenes , a possible separation could not 
be obtained merely by distillation, since both boil at the 
same temperature. The mon- brom derivatives of these com- 
pounds hov/ever, boil at about ten degrees apart; that of 
the meta compound at about 224° and those of the para at 
about 234°. 

136^^- grams of the fraction 175-176, obtained by redis- 
tillation of the original 17C°-185° fraction, was brominated 
in the cold, using 10 g. of iodine as a carrier, with 162 
grams of bromine. The product after being washed and dryed 
gave the follov/ing: 

3.7 g. - 160°-195° C. 
11.2 g. - 195^-220° 0. 
para 160 g. - 228°- 240°G 

6 g. - 2400-2470C. 
£5 g. - Residue 
The fraction 228°-240°C. represents a yield of SO^-i of the 
brom derivatives of para- methyl isopropyl benzene, llelbe-'- 
states that by the Friedel and Crafts reaction using toluene 
isopropyl iodide and AlClg he obtained meta methyl isopropyl 
benzene. He obtained only a small quantity of his product 
and his method of identification which consisted in observing 
the solubility of barium salt of the corresponding di-carbox- 
ylic acid was unsatisfactory. 

1. Ann. 210 . 10 



-35- 



PROPYLENE AIID NAPTHAIEIIE 

Since ethylene and napthalene react only very slowly 
in the presence of iUCl^, it was to be expected that pro- 
pylene and napthalene would react even slower. Instead of 
propylene, diisopropyl benzene was used. 

217 grams of napthalene was stirred with 132 g. of di- 
isopropyl benzene in the presence of 50 g. of AICI3 at a 
temperature of 90°C. for a period of 4-^- hours. The product 
on fractionation gave the following: 

72 g. mono isopropyl benzene 15C°-185° 

72 g. of napthalene 185°- 250° 

15 g. isopropyl napthalene (264°-2660) 
9 g. E66°-50C° probably diisopropyl napthalene. 

50 g. of an oil boiling above 300° C. 

T3TRAHYDR0 BENZSHS AIJD BENZEIIE 

Since tetrahydro benzene contains an ethylene lini:age 
it was thought that it would react with benzene in the same 
manner as has been shov/n in the case of ethylene and pro- 
pylene. The product expected was phenyl cyclohexane 



:0: tc. - ^"v-; 



-36- 



3.54 mols of totra-hydro benzene were mixed with 3.54 
mols of benzene and treated very gradually with 60 grama 
of AICI3. On the addition of the AICI3 a violent reaction 
tool: place with the liberation of large amounts of heat. 
After the 60 grams of AICI3 had been added, the reaction 
bottle was connected with the stirrer. The mixture could 
not however be stirred for periods longer than 30 seconds, 
as the amount of heat liberated was sx;ch as to cause the 
liquid to boil. As the reaction proceeded the mixture could 
be stirred for increasing periods of time. After about 45 
minutes it was possible to stir the mixture continuously and 
this was done for a period of five hours; during which the 
temperature of the mixture remained at about 55 degrees. 
At the end of five hours of stirring the temperature began 
to fall. The reaction product was purified and dryed and 
on distillation gave the following fractions: 

30 g. up to 230° - mostly benzene, cyclohexyl chloride 
(141.3) and tetrahydro benzene 

50 g. 2300-245° Phenyl cyclohexane 
125 g. above 245° - lil:ely diphenyl cyclohexane and 
small amounts of dihexyl . 

Ilursanoff-^ prepared phenyl cyclohexane from cyclo- 
hexyl chloride, benzene and AICI3. 

1. Ann. 518. 310 



•37- 



To 100 grams of benzene and 10 grams of AlCl^ ho 
added slowly 50 grams of AICI3 he added slowly 50 grams of 
cyclohexyl c}iloride and obtained the following prodiicts: 

10 g. up to 130° mostly benzene 

34 g. 1300-1320 (10 mm.) Phenyl cyclohexane 
1 drop 1320-200° (10 mm. ) 

16 g. 2000-515° (20 mm.) diphenyl cyclohexane 
Ke showed that the latter was an ortho compound by prepar- 
ing it from ortho dichlorcyclohexane. 

Kursanoff states that the more AICI3 used the lower the 
percentage of phenyl cyclohexane obtained while the higher 
the percentage of higher boiling products. As an example of 
this he obtained a 11 percent yield 01 phenyl cyclohexane 
by using 30 g, of AlCl^, 20 g. of chlor cyclohexane and 40 g, 
of benzene whereas by using 0.1 g. of AICI3 under the same 
conditions he obtained a 68 percent yield of phenyl cyclo- 
hexane. This night explain why in the present work such 
a high percentage of higher boiling prodiicts were obtained. 

An effort was made to prepare phenyl cyclohexane by 
the Pittig synthesis. To 15 grans of finely divided sodium 
65 cc. of alcohol free dry ether were added. A nixture 
of 35 g. of brom benzene and 35 g. of cyclohexyl bromide 
were then added. The reaction began immediately and cooling 



-38- 



was necessary for its control. After standing over ni.'^ht 
the product was distilled. A yield of 6-7 grans of phenyl 
cyclohexane was obtained which corresponds to about 18',>; - 
20-/i of the theory. 

Phenyl cyclohexane has also been prepared by reducing 
diphenyl v/ith hydrogen in the presence of catalytic nickel"'-. 

SIMIARY 

1. Benzene, Toluene and Ilapthalene may be alkylated 
readily by define and Polymethylene hydrocarbons in the 
presence of aliuniniim chloride with the aid of high speed 
stirring. By this method these alkyl compounds may be 
prepared more rapidly than is possible by the ordinary 
Priedel and Crafts reaction. 

2. The rate at which alkylation will take place de- 
pends largely upon the relative amcants of aromatic hydro- 
carbon and aluminum chloride used. 

3. The two layers which are always obtained in the 
?riedel and Crafts reaction differ widely in the percentage 
of products present. The AlCl^ which is found almost wholly 
in the lower layer retains the higher boiling or more al- 
kylated products. 

4. The lower alkyl benzenes may be alkylated with 

1. 0(1912) 11, 191 



-39- 



greater ease than benzene. 

5. The larger the alkyl group the more difficult ii 
its entrance into the benzene ring. 



-40- 

II. 

THii CHLOI^INATIOIJ OF ACETYLENE 

The object of this work was to prepare tetra- and 
hexa-chloretharles from chlorine and acetylene using a 
liquid medium into which the two gases could be dispersed 
by means of a high speed stirrer, it was thought that 
saturation with water vapor, of the gases included within 
the Eiinute bubbles occasioned by the vigorous stirring, 
might cause a change in the usual course of the reaction. 
The reaction usually proceeds with explosive violence to 
give hydrochloric acid and free carbon. 

Chlorine and acetylene were introduced into the cone 
of the stirrer simultaneously by different inlet tubes. 

EXPERIMENTAL 
500 cc. of water was placed in the reaction bottle 
and a run made at room temperature. Explosions took place 
continuously from the start which gave rise to numerous 
scintillations throughout the liquid. It was thought that 
by using a large excess of one of the gases that the ex- 
plosions could be prevented, but this was found not to be 
true. Explosions took place in every case irrespective of 
the richness of the mixture. It was then decided to pass 
the gases into boiling water v/ith the view that the increase 



■41- 



in water vapor would tend to dilute the P:a3es and thereby 
reduce the violent action, iixploaions did not occur in 
any case with temperatures above 65° C. 

Sometime after this work was completed there appeared 
an riif^lish patent #174,6351 in which it was stated that the 
chlorination oi acetylene could be controlled in the presence 
01 steam superheated to 400°-500° C. 

Motmeyrat^ has studied the action of chlorine on acety- 
lene. He states that ethylene dichloride in the presence of 
aluminum chloride at 70°-75° decomposes to give acetylene 
and hydrochloric acid 

(1) C2H4CI2 > C2H2 + 2 HCl 

He chlorinated C2H4CI2 under these conditions and got C2H2CI4. 
Assuming that reaction (1) does take place he accounts for 
the fact that no explosions occurred on chlorination by say- 
ing that there was a total absence of oxygen. If the presence 
of oxygen be the cause of the explosions then we would expect 
that on passing the gases through water, the dissolved 
oxygen would be expelled and that the explosions v/ould gradu- 
ally cease. This, however, was not the case. 



1. Chem. Abs. 16, 1779 

2. Bull. soc. chim. 19, 448 



-42- 



Aftor the water had been stirred for one hour at a 
temperature of 80° using 350 cc. of Clo and 1400 cc. of 
C2H2 per minute, an emulsion was formed and very effective 
stirring was taking place. A current of air had to bo 
directed on the end of the exhaust pipe to prevent the 
exhaust gases from igniting. The fact that the exliaust 
gases after leaving the refl\r:c condenser would catch fire, 
Wiiile no explosions were occurring in the reaction bottle 
seeir.s to indicate that water vapor had a great influence 
in preventing explosions in the chamber; ot that due to 
the heating practically all of the oxygen was driven out. 
Refluxing began at 76° C After two hours at the above 
rates of flow the product was fractioned. Three drops of 
a coloi-less oil, heavier than water, having a boiling point 
at about 90° were obtained. This i)il has an odor which at 
first is etherial but on further inhalation becomes ex- 
tremely pxmgent. The odor was identical with that of di- 
chloracetaldehyde. It is known that acetylene and water 
react slightly to give acetaldehyde 

CgHg + HgO — ^ CH3CHO 

It is likely that a small amoimt of this compoiuid was formed, 
which on chlorination gave dichlor-acetaldehyde. 

After the water fraction had come over 50 g. of a color- 
less, odorless oil, boiling at 109° and having a specific 



gravity of 1.C889 was obtained. Theue physical duta do 
not check with those of any of the compoirnds which could 
be e:>rpected. 

THE CHLORIMTIOII OF ACiilTYLiillS 
BY THE USE OF SULPHUS DICHLORIDE 

Since acetylene coiild not be chlorinated under the 
conditions as set forth above, work was undertaken to study 
its chlorination by the use of sulphur dichloride according 
to the method of I.Iichel-'- . This consists in alternately 
passing chlorine and acetylene into a mixture of sulphur 
monochloride and 2% hydrogen reduced iron. I.Iichel simply 
allowed these gases to bubble through the mixture; he states 
that a good yield of hexa-chlorethane can be obtained in 
this waj^. The reactions v;hich take place are: 
(1) SgClg + Clg -^ 2 SClg 
(Z) CgHg ■\- 4 SClg -^CgHgCl^ +2 SgClg 
(3) CgHg + 6 SClg -^CgClg + 3 SgClg 

In the first experiment the temperature was so regu- 
lated that gentle reflxrxing took place, oince the reaction 
SgClg + Clg ^ 2 SClg 

1. /ieit. Angew. Chem. 19, 1095 



■44- 



is exotherrdc and since fiirthor the 'boilinf? point of -jClg , 
which is being formed, is lower than that of SgClj), a 
cooling coil was placed aroimd the reaction vessel and the 
wliole immersed in an oil bath. The temperature at the begin- 
ning was held at 125°. Chlorine was stirred into 1057 g. 
of S2CI2 at a rate of 1500 cc. per minute for 10 minutes; 
total absorption talcing place. At the end of this period 
the entire contents of the reaction vessel was forced out 
of the liquid seal witli exj-^losive violence. This could 
have been d\ie to the instability of sulphur dichloride or 
to the clogging of the exhaust line. The latter was found 
not to have been the cause. 

In the follov/ing experiments the temperature during 
chlorinations was held at 40°; this seemed to help rather 
than hinder the rate of chlorination. The absorption of 
acetylene however occurred more rapidly at somewhat more 
elevated temperatures. The heat liberated during the ab- 
sorption 01 acetylene v/as used to raise the temperature 
of the mixture to about 80° C. 

It was not found necessary to remove the excess of 
acetylene by means of an inert gas such as COg before a 
new chlorination. 

The flow 01 chlorine was measured by a calibrated flow- 
m.eter, the acetylene by means of a wet meter. 

The chlorination of sulphur monochloride took place 



■45- 



with eictroue ease; it being possible to get 1299 g. of 
the monochloride to absorb as high as 7000 cc. of chlorine 
per minute. 

In the case oi' the absorption oi" acetylene the reac- 
tion proceeded in a manner which is often found when work- 
ing with catalysts, namely that the reaction had to gradual- 
ly "build itself up". By this is meant that although at 
the beginning the catalyst might be distributed throughout 
the sulphur chloride medium rather homogeneously, the acety- 
lene woiild not be taken up at the same rate at which it 
would bo, after the reaction had been in progress for some- 
time. The rate of absorption of acetylene wotLLd always in- 
crease to a maximum and then gradually decrease. This 
phenomenon is not to be explained as being due to the pres- 
ence of small amounts of the chlorethanes, for even when they 
were present at the beginning, the reaction exhibited the 
same behavior. It is likely, however, that this behavior 
can be explained as being due to the formation of an inter- 
mediate compound betv/een Fe and CgHg; which compound later 
catalizes the reaction. 

After the reaction slowed down, the siilphur monochloride 
was chlorinated to the dichloride and this was distilled off. 
The remaining liquid was steam-distilled; this served to 
carry off the liquid tetrachlorethane from the solid hexa- 
chlorethane. In several experiments the sulphur chlorides 



-46- 



were decomposed with water, tlie liberated hydrochloric 
acid neutralised with IJagCOg, and the mixture sterna-dis- 
tilled. The residue consistinp of sulphur and hexachlor- 
Qthane was then extracted with ether. 

In order to get a closer estimate of the relative 
yields, two runs were made and the resulting products were 
worked up together. 



-47- 









RUII 


# 


1 










1299 


S- 


OgClg : 


: 


9. 


61 


mols. 






25 


g. 


Pe 












CHLORIII 


S 












Ac: 


:TYL3I!E 



Time 


flowmeter 


Rate 


Total 


Time 


Flowmeter 


Rate 


Total 


Min. 


P 


cc. 


Cl2 
1. 




P 


cc. 


C2H2 


35 


8 


2550 


89.3 


30 


14 


1000 


30 


61 


6 


2130 


129.9 


78 


14 


1000 


78 


96 






219.2 


45 


14 


1000 


45 










60 


20 


1220 


73.2 










213 






226.2 


110 


6 


2130 


234.3 


15 


20 


1220 


18.3 


2 


11 


3100 


6.2 


5 


15 


1040 


5.2 


16 


24 


4800 


76.8 


4 
37 


15 
8 


1040 
750 


4.2 




317.3 


9.8 


128 


37.5 


11 


42 


7000 


77 


5 


20 


1220 


^6.1 


20 


20 


4350 


80.7 


52 


20 


1220 


63.4 










23 


12 


912 


21 


31 






157.7 


80 






00.5 


27 


24 


4800 


130 


42 


20 


1220 


51.2 










65 


20 


1220 


79.3 










107 






130.5 



282 



824 



437 



484.7 



Average rate of chlorination = 2920 cc. per nin. or 



2.25 cc. Gig per g. S„C1„ per minute. 



-48- 



The averarre rate oi acetylene absorption = 1100 cc. per 
minute, or 0.85 cc. CoHg per g. S^Clo per minute. 

The relative rates of chlorine uptake to acetylene 
uptake are apparently 3:1. V/eight of product z 1410 g. 



RUII # E 



934 g. S2CI0 

25 g. ?e 

Temp. 40° 

CHLORINE 



ACETYL3HE 



Time 


Flow- 
Ileter 


Rate at 


Total 
Gig 


Time 


?1 ov/- 


7/et 


Total 
C2H9 


Rate 
Flow 




P. 


P. 




Leter 


L'-eter 


71 ov/- 


P. 












P. 




meter 










Si. 






£. 


£. 


cc. 


45 


14 


3.55 


160 


3 


15 




3.1 


1040 










101 


8 


89.2 


75.8 


750 


46 


14 


3.55 


155 


87 


8 


61.5 


65.3 


750 


52 


14 


3.55 


184.6 


102 


8 


72.2 


76.5 


750 


57 


14 


3.55 


202.3 
701. 9 


82 


8 


57.1 
280 


61.5 
282.2 


750 


200 


. 374 





Yield of mixture of C2H2CI2 
C2H2CI4 
C2HCI5 



1035 g. 



•49- 



The total products from "both runs amounted to 2445 g. 
which on separation gave tiie lollowinr percentaf^e by weifjht. 





B. P. 


Yield 


% 


C2C16 


Sublimes 


76 g. 


3 


C2HC15 


158° 


49 g. 


2 


C2H2C14 


147° 


1887 g. 


77 


CgHgClg 


84° 


108 g. 


4 



It is qixite evident that this method gives only a very 
small relative amount of hexachlorethane ; the main product 
being s-tetrachloretliane. 

The tetrachlorethane thus prepared was further chlori- 
nated to hexachlorethane in the presence of AICI3. This 
procedure is similar to that used by Llouneyrat by which he 
chlorinated ethylene dichloride to hexachlorethane. 

The chlorine was passed into the mixture at 120° C. The 
density increased with the chlorine absorption until a point 
was reached where the entire contents of the hottle solidified 
and could no longer be stirred. The hexachlor-ethane was freed 
as much as possible from the tetraclilor-othane by suction and 
the former then recrystallized from alcohol. The yield 
of CgClg calculated upon the basis of the amoixnt of chlorine 
used amounted to 63/i. 

The effects of stirring: at a rate of 8000 K.P.LI. on the 



•50- 



rate or absorption of chlorino by tetruchlorethano in tho 
presence of AICI3 was investigated at a point in the chlori- 
nation where the chlorine was being taken up at a rate of 
1400 CO. per minute. The stirring was stopped with the 
result that the flow-meter pressure on the chlorine line 
dropped from 3 cm. indicating a rate of 1400 cc. per minute 
to 1 c:.:. indicating a rate of 750 cc. per minute. The latter 
rate is necessarily greater than it would have been, had not 
the liquid been previously stirred, since as soon as the 
stirring was stopped the AlCl^ was still rather homogeneously 
distributed throughout the liquid. 

C0NCLU3I01IS. 

1. Chlorination of acetylene in the presence of 2% 
catalytic iron gives s-tetrachlorethane almost exclusively. 

E. s-Tetrachlorethane can be chlorinated in the presence 
of AlCl^ using high speed stirring until the reaction mixture 
solidifies, thus giving a yield of 63/0 hexachlorethane. 

3. The effect of high speed stirring was to double the 
rate of chlorination of s-tetrachlorethane to hexachlorethane. 

4. Chlorine and acetylene may be made to react without 
violence in the presence of water vapor above 65° C. 



BIOGiiAPHY 

The author of this dissertation was born in Charles 
Co., iJaryland, ii'ebruary 8, 1897. He received his early 
education in the public schools of Baltimore and graduated 
from The .JOhns Hopkins University in 1920 with the degree 
of Bachelor of Science. In the fall of 19E0 he entered the 
Johns Hopkins Graduate School of Ghe;nistry, taking as his 
subordinate subjects rhysical uhemistry and -lathematics . 
In June 1922 he received the degree of ..iaster of Arts, the 
title of his thesis being:- "The Friedel and Orafts Reaction. 

During the years 1921-22 and 1922-23 he was part-time 
instructor in Organic Chemistry at the Mt. 7ernon College of 
Baltimore and the University of Maryland respectively. 

He was appointed a Hopkins Scholar for the years 1920- 
21. 1921-22 and 1922-23.