THE CONDENSATION OP SOME SECONDARY ALIPHATIC
ALCOHOLS WITH BENZENE IN THE PRESENCE OF
ALUMINUM CHLORIDE

fey
IRVING ALLAN KAYE

A THESIS
Submitted to the Graduate School of Michigan
State College of Agriculture and Applied
Science in partial fulfilment of the
requirements for the degree of
DOCTOR OF PHILOSOPHY

Department of Chemistry
1942

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ACKNOWLEDGMENT
The author wishes to express his appreciation for the
guidance and helpful counsel given him in this work by
Dr* 1* C* Huston*

.
331644.

1.
INTRODUCTION
The reaction of saturated aliphatic and mixed aliphaticaromatic alcohols with benzene and other aromatic compounds,
using aluminum chloride as catalyst, has been the subject of
an intensive Investigation in this laboratory since 1916
when Huston and Friedemann (1) reported the condensation of
benzyl alcohol with benzene*
In the case of the saturated aliphatic alcohols it has
been shown that the tertiary alcohols, up to and including
those containing eight carbon atoms, condense readily, and
in good yield for the most part, with benzene to give the
expected products*
The secondary alcohols in this series have not been
studied as thoroughly*

Isopropyl, secondary butyl, the

secondary amyl and four of the secondary hexyl alcohols have
been condensed with benzene by Huston and Hsleh (2), Thompson
(3) , and Applegate (4)*

However the yields of alkylbenzenes

were rather poor and the nature of the products was not
ascertained*
It Is the purpose of the present investigation to fur­
ther the work begun by these men with a view to Improving
their yields and determining the nature of the products*

HISTORICAL
Humerous methods 3m ve been used to prepare alkylbenzenes*

As a rule these methods have been restricted to the

preparation of the lower members, but in most eases they can,
and in some cases have been, extended to the higher homologues.
The simplest secondary alkylbenzene, eumene? was first
prepared by the distillation of para cumic acid with cal­
cium or barium oxides <5-6}*

It was thought to be normal

propylbenzene until Liebraann (7) showed it to have the second­
ary structure by preparing it from benzal diehloride and
dimethyl zinc*

Sabatier and coworkers (8-9) prepared it by

passing the vapors of various terpenes with hydrogen over
nickel at 350-560 degrees centigrade*
Decarboxylation by the distillation of an aromatic acid
In the presence of a strong base has been used, too, to
prepare a higher alkylbenzene*

Pulvermacher (10) obtained

2-phenylpentane by distilling a mixture of alpha, alpha
diethylhomophthalie acid anhydride, calcium oxide and sodium
hydroxide#
Llebmann,s method, involving the reaction of zinc alkyls
with phenylmethyl halides, has been used to prepare other
alkylbenzenes#

Diethyl zinc and benzyl chloride have yielded

n-propylbenzene (11-12) and 2-phenylpentane (13)*

The

latter compound has also been prepared by the action of
diethyl zinc on trichlorophenylmethane (14), though In
poorer yield#

Sec *-butylbenzene has been prepared by react­

ing diethyl zinc with alpha phenylethyl bromide (15)#

The Wurtz reaction and some of its modifications have
also been used.

Cumene has been prepared by reacting sodium

with a boiling ether or benzene solution of bromobenzene
and isopropyl bromide (16).

See.-butylbenzene has been

prepared in similar fashion from ethyl iodide and alpha
phenylethyl bromide (17)*

Sodium benzyl gave n-phenyIhexane

on treatment with n-amyl chloride {18) • The Grignard reac­
tion has been used similarly for the preparation of 5phenylpentane from ethylmagnesium bromide and 1-brom-lphenylpropane (19) as well as from phenyl magnesium bromide
and 5-bromopentane {20)•
Alkylbenzenes have been prepared by the reduction of
their halogen substituted derivatives, see.-butylbenzene
being formed by reducing the 3-ehloro or 3-bromo derivative
with sodium (21), while a-phenyIhexane and n-phenylheptane
have been prepared similarly from their corresponding 6and 7-chloro derivatives (22)*
Other compounds that have been reduced to alkylbenzenes
are ketones, acids and ketoacids*

Hydrogen, in the presence

of nickel has been used to reduce n-amyl and n-hexylphenyl
ketones to the corresponding hydrocarbons (23)*

This is an

excellent method for the preparation of the normal alkyl­
benzenes since the ketones are easily prepared by condensing
acyl halides (24) or acid anhydrides (25) with aromatic
nuclei.

In place of nickel and hydrogen, sodamide has effected

the reduction of sec.-amylphenyl ketone (26) and 3-benzoylhexane (27).

Phosphorus and hydriodic acid have been used

to reduce 2-methy1-5-phenylpentanone-3 (28)•

The ethyl ester

4
of 2-phenylbutyric acid gave a fair yield of sec--butylbenzene on reduction with a copper-chromium oxide catalyst
(29)*

Electrolytic reduction has produced the hydrocarbon

from the ethyl ester of methylbenzylacetoacetlc acid (30)•
Perhaps one of the best methods available for the prep­
aration of a pure, unrearranged alkylbenzene is that in­
volving the Grignard reagent*

Hormal propylbenzene can be

prepared in excellent yield by the action of diethyl sulfate
(31) or para ethyl toluene sulfonate with benzylmagneslum
chloride (32)*

Propyl sulfate and phenylmagneslum bromide

gave a ten per cent yield of cumene (33)*

The product

formed by the reaction of phenylmagne sium bromide with
n-heptaldehyde on reduction gave n-phenylheptane <34),
while di-isopropyl ketone, treated in the same fashion, gave
2,4 dimethy1-5-phenylpentane (35)*
Klages has prepared many alkylbenzenes by a synthesis
Involving the use of the Grignard reagent-

He treated a

ketone, as acetophenone, with the appropriate alkylmagneslum
halide to form a tertiary alcohol which split out water
easily to yield an unsaturated compound.

The olefin, on

reduction with sodium and absolute alcohol, gave the alkyl­
benzene in good yield*

In this fashion were prepared

n-propylbenzene (36), cumene (37), see.-butylbenzene (38),
the 2 and 3-phenylp©ntanes (37-39), 2-methyl-3-phenyIbutane
(39), 2-methy1-4-phenyIpentane (40), 3-methyl-1-phenylpent&ne (41), and 2-me thy1-5-phenyIhexane (38)*

In the course of their studies on the relationship
between molecular structure and optical activity, Levene and
Marker synthesized quit© a few alkylbenzenes.

Their syn­

theses usually consisted of the replacement of the hydroxyl
group of a primary phenyl substituted alcohol by a carbinol
group.

This was accomplished by replacing the hydroxyl

group first by bromine, forming the Grignard reagent of the
halide and condensing it with formaldehyde to give an alcohol
containing on© more carbon atom than the original starting
compound*

This was then converted to the corresponding

bromide, the Grignard reagent of this compound formed, and
subsequently treated with a substance containing active
hydrogen to yield the alkylbenzene*

Using tills procedure,

they prepared 3-phenyIp©ntane (42), the 2- and 3-pheny1hexanes (43) and 3-phenylhept ane (43)*
More popular than any of the preceding reactions for
the preparation of alkylbenzenes is the condensation reac­
tion wherein an alkyl halide, ether, alcohol, ester, olefin
or naphthene is combined directly with an aromatic nucleus
In the presence of some catalytic agent.

The latter is

usually a strong dehydrating agent, as zinc chloride, sul­
furic acid, aluminum chlorde, hydrogen fluoride or boron
fluoride*
This method Is far more direct and rapid and gives much
better yields of alkylbenzenes.

The chief disadvantage,

however, lies in the fact that rearrangement frequently
accompanies the reaction, giving an altogether different

6*
product from that expected, or a mixture of several products,
difficult to separate*
formal propyl and isopropyl halides both give cumene
on condensing with benzene (44,45,72)*

Condensing agents

used in this reaction have been aluminum chloride (46),
(72), aluminum bromide (47), aluminum turnings and hydrogen
chloride gas (48), and hydrogen fluoride (45)*

Simons and

Archer (45) reported that their product* when n-propyl
chloride was condensed in the presence of hydrogen fluoride,
consisted of the rearranged secondary product to the extent
of eighty eight per cent*

Ipatieff, using aluminum chloride

(72), obtained a mixed product of similar composition*
Hormal or secondary butyl chloride, In condensing with
benzene In the presence of aluminum turnings and mercuric
chloride (49), or aluminum chloride alone (50), gave only
the secondary product*

Konovalov and Jegorov (51) found

that Iso amyl and tertiary amylbenzenes are formed In addi­
tion to the secondary product when 2-me thy1-3- chlorobutane
was condensed with benzene in the presence of aluminum
chloride*

Curiously enough, no rearrangement was reported

in the condensation of 1,1-diehloroheptane with benzene,
aluminum chloride acting as catalyst*
was normal phenylheptane (52-53)*

The product formed

Tertiary alkyl halides

and benzene give the expected product in the presence of
aluminum chloride#

In this manner were 3-methyl-3-

phenyIhexane (54), 2,5-dimethy1-2-phenyIhexane (55), and
3-ethyl-3-phenylpentane (55) prepared#

7*
Olefins, too, have been condensed with benzene to form
alkylbenzenes-

The catalysts used have been aluminum chlor­

ide and hydrogen chloride gas (46), sulfuric acid, either
alone (57,72) or in conjunction with phosphoric acid (56),
hydrogen fluoride (55) and boron fluoride (59)*

Propene

gave cumene (56,59), butene see.-butylbenzene (57), isopropylethylene tert.-amylbenzene in the presence of sulfuric
acid (60,72) and 3-methy1-2-phenylbutane in the presence
of aluminum chloride (72), and hexene-1 gave 2-phenyIhexane
(61).

Ipatieff (72) considers sulfuric acid a stronger

isomer1zing agent than aluminum chloride in the condensa­
tion of olefins*
Compounds other than olefins, which also exhibit strain,
can be condensed*

Some naphthenes, of which cyclopropane

is the simplest, have been condensed with benzene*

Ipatieff

and coworkers (72) found that the aluminum chloride-catalyzed
reaction, whether carried out at zero or seventy one degrees
centigrade, gave the same product, normal propylbenzene*
The use of sulfuric acid, on the contrary, results in the
formation of cumene*
In similar fashion and with similar rearrangements have
esters (62,101-102) and ethers (105) been condensed with
benzene*

In the case of the esters some anomalous results

have been reported*

Bowden (62) reported that n-propyl

esters of formic, acetic and sulfuric acids gave normal
propylbenzene when aluminum chloride was used as catalyst*
The corresponding n-butyl esters gave see.-butylbenzene

8.
and the isobutyl esters tert.-butylben.zene.

Contrast this

with the work of McKenna and Sowa (63) who found that npropyl formate gave isopropylbenzene in the presence of
boron fluoride.
More recently have the alcohols achieved prominence
in this condensation reaction with benzene and other aromatic
nuclei.

Condensations in the presence of zinc chloride (64),

sulfuric acid (65), aluminum chloride (66) (76, 100), boron
fluoride (67), and hydrogen fluoride (68) have been reported.
In general it has been found that tertiary alcohols give
no rearrangement, though fragmentation has been found to
occur with the higher highly branched members (69, 70).
Touasaint and Hennlon (71) found that primary alcohols gave
the secondary alkylbenzene exclusively when boron fluoride
was the catalyst*

On the other hand, Ipatieff (78) reported

that n-propyl alcohol gave n-propylbenzene exclusively in
the presence of aluminum chloride*

While seemingly in con­

flict, these results are in harmony with those of others
using the corresponding esters.

In keeping with the find­

ings of Toussaint and Hennion, Meyer and Bemhauer (44)
obtained sec.-butyIbenzene from both normal and secondary
butyl alcohols in the presence of sulfuric acid.

Isopropyl

alcohol has been found to give only the secondary alkylbenzene In the presence of aluminum chloride (73-74).
The Chemical laboratories of Michigan State College have
witnessed considerable progress in the condensation of various**
alcohols with aromatic nuclei in the presence of aluminum

9.
chloride*

This catalyst was first used in tbs condensation

of alcohols with aromatic nuclei by Nef (75) who, In 1897,
prepared diphenyIme thane by allowing benzyl alcohol to react
with benzene in Its presence*

This work was repeated in

1916 by Huston and Friedemann {1} and a thirty per cent
yield of dlphenylmethame was reported*
This was followed tip by the condensation of mixed
aliphatic-aromatic and true aromatic secondary alcohols
with benzene (76)*

Huston (77} later used phenol and its

methyl and ethyl ethers in place of benzene and found that
benzyl alcohol gave yields of 46-50 per cent of alkylated
products*
In 1926 Huston and Sager (78) investigated the reaction
of primary alcohols with benzene but were unsucessful in
condensing methyl, ethyl, propyl, iaopropyl, n-butyl,
isobutyl, isoamyl, phenylethy1 and phenylpropyl alcohols*
They did succeed In getting a 16 per cent yield of allylbenzene from allyl alcohol*

This alcohol was later condensed

with phenol by Huston and Hewmann (79)•

The conclusion was

then drawn that aluminum chloride favored condensation only
when the alpha carbon of the alcohol was double bonded or
the member of a benzene ring*
Confirmation of this theory was obtained in the work
of Huston, Lewis and Grotemut (80) who condensed phenol with
benzhydrol, methylphenylcarblnol and ©thylphenylearbinol.
Benzhydrol, in which both carbon atoms adjacent the earbinol
group are members of a benzene ring, gave a much larger

10.
yield of alkylated product than benzyl alcohol under the
same conditions.

This was pointed out as definite evidence

that aromatic unsaturation has a pronounced effect on the
activity of the hydroxyl group*
In 1933 Huston and Davis (81) found that the tertiary
alcohol, triphenyl carbinol, reacted with benzene to give
trlphenyl methane instead of the expected tetraphenylmethane *
Huston and coworkers (82-84) condensed benzyl and
halogenated benzyl alcohols with phenol and halogenated
phenols and with the eresols and their halogenated deriva­
tives*

In each ease, two mono substituted and one disubstituted

derivatives were obtained.
To Investigate the effect of unsaturation of the alpha
carbon atom on condensation, Huston and Goodemoot (85) com­
pared the reactivities of eyelohexyl, cyclopentyl and cyclobutyl carbinols with benzene.

They found a progressive

increase in activity as the number of carbon atoms of the
ring was reduced from six to four.
Investigation of several diaryl-alkyl and dialky1-aryl
carbinols by Huston and Wilsey (86), Huston and Hradel (87),
and Huston and Mac Comber (88) showed that they did not con­
dense with benzene but were dehydrated yielding the
corresponding unsaturated products*
All these experiments indicate that unsaturation of
the alpha carbon atom, whether it be that of an ordinary
double bond or that of a benzene ring, favors condensation
reactions of aliphatic and aromatic alcohols with aromatic

11*
hydrocarbons and phenols in the presence of aluminum chlor­
ide*
The groundwork for the condensation of saturated ali­
phatic alcohols with benzene and phenol was laid by Huston
and Hsieh (2) in 1956*

They prepared cumene in fair yield

by reacting isopropyl alcohol with benzene and followed up
this work with the condensation of simple aliphatic primary,
secondary, and tertiary alcohols with benzene and phenol•
It was found that under the conditions of their experiment,
primary alcohols would not condense with either phenol or
benzene while secondary and tertiary alcohols reacted with
both benzene and phenol*

They also condensed some tertiary

alcohols with toluene, meta cresyl methyl ether and anisole*
In 1934 Huston and Fox (89} condensed tertiary butyl,
tertiary amyl and the three tertiary hexyl alcohols with
benzene*

These alcohols had already been condensed with

phenol by Huston and Hsieh (2)*

fsukervanik (73-74, 100)

condensed seme simple secondary and tertiary alcohols with
benzene and toluene and obtained results similar to those
of Huston and Hsieh (2) and Huston and Fox (89)*
Since the tertiary aliphatic alcohols condensed readily
with both benzene and phenol, the condensation of the higher
tertiary aliphatic alcohols was studied*

Huston and Binder

(90) condensed the tertiary heptyl alcohols with benzene
and Huston and Hedrick (91) condensed the same alcohols
with phenol*
The condensation of the tertiary octyl alcohols with

12.
benzene and phenol was investigated by several later workers*
Huston and Anderson (92) condensed methyl©thyl-n~butyl and
me thyle thyl-tert•-butylcarbinols with benzene and phenol.
Huston and Sculatl (93) reacted some of the dimethylamylearblnols with benzene*

Huston and Cline (94) and Huston

and Brelning (95) worked with the methyldipropyl and propyldiethyl carbinols respectively*

In 1940 Huston and Wasson

(69) condensed scan© dimethylamylcarbinols with benzene, and
Huston and Guile (70) condensed the dimethylamylearbinols
with phenol.

Fragmentation of the carbon chain was found

to occur when the amyl radical was highly branched*

As a

result of this fragmentation, some alkylphenols of lower
molecular weight were obtained.
In 1940 Huston and Jackson (96) reported the condensa­
tion of some diphenylalkylcarbinols with phenol and Huston
and Hughes (97) continued the Investigation of the reaction
of dialkylarylcarbinols with phenol.
In the same year Huston and Esterdahl (98) condensed
the secondary amyl alcohols with phenol and found that a
mixture of produets was formed as though a dehydration of
the alcohol had occurred in the reaction followed by the
condensation of the phenol with the olefin formed*

Similar

results were found by Huston and Curtis (99) the next year
when they studied the reaction of the secondary hexyl
alcohols with phenol, and by Tsukervanik and Hazaranova
(100) who obtained a mixture of the 2- and 3-p-hydroxyphenylpentanes when methylpropylcarbinol was condensed

13.
with phenol in the presence of aluminum chloride*
This investigation is a continuation of the work begun
in this laboratory on the condensation of the secondary
alcohols*

The propyl, butyl, amyl, hexyl, and some of the

heptyl secondary alcohols were condensed with benzene under
the influence of aluminum chloride and the nature of the
products was studied*

14 •

THEORETICAL
It will be shown later that the results of this study,
in agreement with those of other workers at this laboratory
and elsewhere, would indicate that the condensation of a
secondary aliphatic alcohol with benzene, in the presence
of aluminum chloride, takes place with the splitting out
of water and the condensation of the resulting olefin*
fsukervanik and Bazaranova (100) have suggested as a
mechanism for the condensation of the tertiary alcohols,
the formation of an Intermediate compound from the alcohol
and the aluminum chloride, hydrogen chloride being eliminated
simultaneously*

An olefin is then thought to be formed by

the scission of this compound*

The olefin can then combine

with the hydrogen chloride that has been eliminated to form
an alkyl halide which then condenses with the aromatic
nucleus in true Prled® 1-Grafts style*

The reaction may be

represented as follows*
(1)

(CHs)aCGM ♦ A i d * — >

AlClaGC(CHa)a + H d

(2)

Ald»QC(CH*}* --> (CHa)#-C*CH* + Ald*0H

(3)

(CHa)aC«CH* ♦ H d — * (CBa)aC-d

(4)

(CHa)a-C-Cl ♦ C«H« — »

(CH8)a-C-CeH* + HOI

However, it is difficult to conceive of the formation
of the intermediate aluminate by the replacement of the
hydrogen atom of the tertiary hydroxyl grouping*

The theory,

too, conflicts with work of Huston and Hedrick (91) who

15.
found that hydrogen chloride Is evolved when aluminum chlor­
ide Is treated with a petroleum ether solution of a tertiary
alcohol.

According to the above mechanism, no hydrogen

chloride should be evolved until the aromatic nucleus has
been introduced and condensation taken place.
TsukervanIk,s mechanism for the condensation of second­
ary alcohols with benzene (73) la supported by Ipatieff (72),
but fails to explain the rearrangement obtained in this
present study.

The intermediate aluminum alkoxy compound

Is thought to react directly with benzene without prior
splitting and formation of the olefin.

Cumene may be pic­

tured as being formed from isopropyl alcohol and benzene
In the following fashions
(1)

sec.-C3H7OH + AlCla -— * sec.-C8H7QAlCla + HC1

(2)

sec.-C3H7OAlCXa 4- ceBe Alc3^

sec.-C8B 7C€H8 + H0A1C1*

McKenna and Sowa (67) propose as a mechanism for the
condensation of alcohols, with boron trifluoride as catalyst,
the formation of an alkene by the dehydration of the alcohol.
See.-butylbenzene may be formed from n-butyl alcohol In this
manner.
(1)

CHa-CH*-<m8-CH«0H

CHa-CBa-CH=CH8 ♦ H*0

(2) CHa-CH*-CH=CHa ♦ CSH* -— > CH8GH*-GH~C8B8
CHa
The condensation of unsaturated hydrocarbons with
aluminum chloride as catalyst {72} gives support to this
theory.
An excellent discussion of the eatinoid theory of

16.
condensation may be found in a review by Price (134)*

An

i

ionic type of mechanism is postulated for all aeylations
with acid chlorides, anhydrides and esters, and alkylationa
with alkyl halides, alcohols, ethers, esters or olefins
using such compounds as boron, aluminum or iron halides,
as well as, sulfuric, phosphoric, ox* hydrofluoric acids as
catalysts *
An ionic complex between aluminum chloride and the
alcohol is first assumed to be formed#
GHa-CEs-CH-CH* + A1G1® '--- * GHa-CH*-CH-CEa
OH
0-H
i
CW1-C1
Cl
In this complex the carbon-oxygen bond is weakened, probably
due to the greater attraction of aluminum for the electrons
of the oxygen, and the compound dissociates into an electrondeficient carbonium ion and a negatively charged aluminum
complex#
CHa-CE»-CH-CHa ---■* (CHs-CHa-GH-CB^ faO-Al-Cl®) ~
0-H
*
I

C1-A1-C1
Cl
The carbonium ion can then complete its octet of electrons
by association with a pair of electrons from a double bond
of the aromatic nucleus#

0

>
,

^

H
-CE-CEa-CH®

' CH®
-CH-CHa-CHa + H+

17.
d-Sec*-butyl alcohol, in the presence of boron fluoride,
was found to yield a see.-butylbenzene product, 95 per cent
of which was a racemlc mixture, the remainder being the
laevo form.

This phenomenon was explained on the basis of

the life period of the cation.

If the asymmetric alkyl

cation reacts almost simultaneously with the process of
ionization, the only avenue of approach is at the face
opposite that being vacated by the anion.

Complete inver­

sion of the configuration would then occur.

The longer the

life of the cation, however, the more extensive would be
Its racemization before subsequent reaction.
If the catlnoid theory were correct, the results of
i
this present investigation might indicate a further change
occurring In the carbonium ion formed In the reaction,
possibly a dynamic equilibrium involving the shift of a
hydrogen from an adjacent atom to the carbon containing
the positive charge.

The result would be a shift of the

positive charge, too, to the adjacent carbon atom.
(BaC-CHs-CHa-eE-CHa) or
<U

*

S

(H*C-CHa i| s§s CH»\+
%
If H
\
(h s c -gh 8 ?C ids CH3 + H+) +

♦)+

^HsjC-CH* ?C :C :CH3 + H /

^

/
HE
v
(HaC-CHa-C-C-CH3J
(II)

A mixture of carbonium Ions I and II would result which,
on condensation with benzene, would give a mixture of the
2 and 3 phenylpentanes.

18*
In like fashion, the formation of a tert.-alkylbenzene
from an alcohol having an adjacent branched methyl group
might be explained*

What the correct mechanism for the condensation of
secondary alcohols with benzene is cannot be ventured to
be said at present*

Suffice it to say that the reaction

appears to proceed with the elimination of water followed
by the subsequent condensation of the olefin formed*

EXPERIMENTAL

I* Preliminary
The problem of condensing secondary aliphatic alcohols
with benzene first necessitated an Improvement In the yields
of alkylated products obtained by previous workers in this
laboratory*

Their studies were quite extensive, Involving

condensations in petroleum ether solution using a slight
excess of benzene and one-eighth to onf-half mole of
aluminum chloride*
In order to improve the yields, the preparation of cumene
was studied*

A much greater excess of benzene was used,

petroleum ether was omitted, more aluminum chloride was
employed and dry hydrogen chloride gas was bubbled through
the reaction mixture In an attempt to remove the water
formed in the reaction*

Ail these factors, it was hoped,

would make the reaction,
H
R-C-R* + C*H«
OH

H
R-C-R* + Ha0

go more to completion*
The first factor studied was the amount of aluminum
chloride to be added*

The proportions of reactants used

are shown in Table X*

It was found that poor yields resulted

when much aluminum chloride was used, many side-reaeti ons
taking place*

This Is In accordance with the observation

of Tsukervanik (100) who reported that an excess of aluminum

20.
Table 1

Benzene

Isopropyl Alcohol

A1C1S

Yield of
Climene

100 grams

13*7 grams

30 grams(0.5 mole)

450 ml*(5 moles)

30 grams

450 ml*

25 grams

30 grams

450 ml*

50 grams 35*0 grams

0*0 grams

chloride resulted In the formation of polyalkyl compounds*
Too little catalyst gave no yield at all*

Good results were

obtained with 50 grams of aluminum chloride*

It is to be

noted that these reactions were carried out, unlike later
experiments, at, or below, room temperature*
In later work, under conditions

It was found

finally worked out, that

the amount of catalyst could be reduced to 35 grams with
no decrease in yield*
Smaller amounts of benzene were next tried but given
up after a few attempts*

Viscous gels were formed, when

the aluminum chloride dissolved, which were difficult to
stir and decreased the yields considerably*

It was found

that when a ratio of ten moles of benzene to one of alcohol
was used, the aluminum chloride dissolved easily to give a
clear, non*viscous, yellow, orange or brown solution*
Another factor studied was the influence of temperature
upon the yield*

It was found that the suspension of aluminum

chloride in benzene should be kept cold when the alcohol
was being introduced*

This fact is borne out by a reaction

carried out at two different temperatures*

When the alcohol

was added to the boiling suspension, a 36 per cent yield of

21.
cumene resulted*

The yield rose to 53 per cent when the

same experiment was repeated at zero degrees centigrade*
Later experiments, using the higher homologues, diethyl,
methyl isobutyl, methyl secondary butyl, methyl isoamyl,
methyl tertiary and ethyl tertiary butyl carbinols, showed
that the reaction could be carried out without external
cooling with no decrease in yield*

The alcohol was added,

In these latter reactions, at such a rate that the tempera­
ture of the system was maintained at about 50 degrees centi­
grade*

The nature of the products was shown to be Identical

with that carried out at the lower temperature.

In fact,

In almost all cases these higher alcohols gave slightly
better yields of alkylbenzene at the higher temperature*
After the alcohol had been added, the reaction mixture
was allowed to remain at room temperature for various periods
of time*

Standing for four or sixty four hours made little

difference in the yield*

A shorter period of time did re­

duce the yield considerably.

Under final conditions, the

reaction mixture was permitted to stand overnight, usually
for a period of eight hours.
After standing a few hours, better yields were obtained
If the reaction mixture was re fluxed*

In one experiment,

the reaction mixture after standing forty eight hours, was
divided into two equal parts*

One was refluxed for three

hours and the other allowed to stand at room temperature
for the same length of time.

The latter gave a fifty seven

per cent yield while the other procedure gave a sixty six

22*
per cent yield*

The yields were even better when the reac­

tion mixture was refluxed seven to eight hours * Under these
conditions* the yield rose to seventy one per cent and was
not Improved by longer refluxing*

This period of re flux­

ing was later abandoned in the condensation of the branched
chain alcohols* sines yields were not improved and in some
cases actually decreased*
The hydrogen chloride gas was found to have a beneficial
effect upon the reaction for in one experiment where it was
omitted the yield dropped from sixty six to sixty per cent*
These conditions were used in all subsequent condensations
with the higher alcohols: namely*
(1) using fifty grams of aluminum chloride for a half
mole run*
(2) using a ratio of ten moles of bensene to one of
alcohol*
(3) adding the alcohol to a suspension of aluminum
chloride in benzene kept in an ice bath with hy­
drogen chloride gas bubbling through the reaction
mixture*
(4) permitting the reaction mixture to stand at room
temperature for about eight hours after the addi­
tion of the alcohol* and
(5) refluxing the reaction mixture for eight hours
longer while bubbling in hydrogen chloride gas
(in the case of alcohols having no branching)*

23.
II* Preparation of Alcohols
In a dry, three liter, three neck, round bottom flask,
fitted with a separatory funnel and soda-llme tube, reflux
condenser and soda-llme tube, and mechanical stirrer with
glycerol seal, were placed 49 grams of magnesium turnings,
a few crystals of Iodine and about 100 ml. of anhydrous
ether*

A few grams of the alkyl halide was added and the

solution stirred*

If necessary, the flask was warmed by

means of a water bath to start the reaction.

After the re­

action began, the external heating was removed and the re­
mainder of the two moles of alkyl halide, dissolved in an
equal volume of anhydrous ether, was added with stirring*
The addition was dropwise, at a rate just sufficient to
cause mild refluxing.

Stirring was continued for almost

15 minutes after the addition of the alkyl halide*
To the Grlgnard reagent was added dropwlse, with cool­
ing and stirring, two moles of the aldehyde dissolved in
an equal volume of anhydrous ether*

Acetaldehyde was pre­

pared by the depolymerization of paraldehyde (104)*
The reaction mixture was decomposed with Ice and suffi­
cient concentrated hydrochloric acid was added to barely
dissolve the basic magnesium salts that were formed*

The

ether layer was then separated and the aqueous layer extracted
twice with ether*

The combined ether extracts were washed

once with water, then with a dilute sodium bicarbonate solu­
tion and then dried over anhydrous sodium sulfate.

The ether

was removed on a steam bath and the alcohol distilled at
atmospheric pressure*

24*

With the exception of methyl isopropyl earbinol, which
was prepared by Mr. Wasson using the Grignard reaction,
the following alcohols were obtained from Eastman Kodak
Company and redistilled over sodium.
(1) Propanol-2

B.Pt. * 82-83°C.

(2) Butanol-2

B.Pt. « 99°C.

(3) Pentano1-2

B.Pt* * 117-118*0.

(4) Pentanol-3

B.Pt* » 115-116*0.

(5) 2-Methylbutanol-3

B.Pt* » 112-114*0*

(6) Hexanol-2

B.Pt. * 156-158°C*

(7) 2-Methylpentanol-4

B.Pt. - 130-132°C.

(8) Hexanol-3 £105-107)
By the Grignard reaction using ethyl bromide £108)
and n-butyral&ehyde#
Yield » 65 per cent
3Ta8 = 133-135°C.
Dja * 0.8227
nj* « 1.4167
Surface Tension at 25*C. * 27.30 dynes
(9) 3-Methylpentanol-2 £109)
By the Grignard reaction using sec.-butyl bromide (108)
and acetaldehyde £104).
I

Yield « 48 per cent
B7Sa * 133*0.
Dj® * 0.8305
n£* * 1.4213
Surface Tension at 25°C. * 28*60 dynes

25.
(10) 2-Methylpentanol-3 (110)
By the Grignard reaction using isopropyl bromide (108)
and propi ona ldehyde •
Yield * 42 per cent
BTes m 125-128*0•
dJ* * 0.8289
nj* * 1.4193
Surface Tension at 25°C. * 28.60 dynes
(11) 2,2-DimethyIbutanol-3 (Pinacolyl Alcohol) (111)
By the Grignard reaction using iert.ibhtyl bromide;(108)
and acetaldehyde.
Yield « 24 per cent
B7aa * 120-124*0.
(12) Heptanol-2 (112)
By the Grignard reaction using n-amyl bromide (108)
and acetaldehyde*
Yield * 75 per cent
B7ea * 157-158*0.
b J*

« 0.8187

nj* * 1.4212
Surface Tension at 25®C. * 28.70 dynes
(13) Heptanol-3 (107)
By the Grignard reaction using n-butyl bromide (108)
and proplonaldehyde.
Yield * 62 per cent
B7e« * 154-156*0.

26.
DJ* * 0.8225
up

* 1*4214

Surface Tension at 25*0. ■ 28.80 dynes
(14) Heptanol-4 (115-117)
By the Grignard reaction using n-propyl bromide (108)
and n-butyraldehyde*
Yield = 75 per cent
B7e* * 154-155*0.
d J*

* 0.8192

»p* « 1.4209
Surface Tension at 25*0. ® 27.80 dynes
(15) 2-Methylhexanol-3 (118-119)
By the Grignard reaction using Isopropyl bromide (108)
and n-butyraldehyde.
Yield * 54 per cent

B-re* * 146-147*0.
Dj1 * 0.8234
n£* * 1.4218
Surface Tension at 25*0. * 27.40 dynes
(16) 3-Methylhexanol-4 (120)
By the Grignard reaction using sec.-butyl bromide (108)
and propionaldahyde •
Yield * 42 per cent
8T9» * 147-148*0.
d J*

* 0.8355

“D* * i-4250

27.
Surface Tension at 25°G. * 28.60 dynes
(17) 2-Methylhexanol-4 (121)
By the Grignard reaction using isobutyl bromide (108)
and propionaldehyde.
Yield * 35 per cent
B768 » 144-146*0.
Dj® « 0.8164
nj* * 1.4187
Surface Tension at 25°C. * 27.10 dynes
(18) 2-Methylhexanol-5 (122)
By the Grignard reaction using isoamyl bromide (108)
and acetaldehyde.
Yield = 73 per cent
B768 * 150.6-152*0.
Dj® * 0.8156
nj* * 1.4200
Surface Tension at 25°C. * 27.00 dynes
(19) 3-Methylhexanol-2 (123)
By the Grignard reaction using 2-chloropentane (124)
and acetaldehyde.
Yield * 57 per cent
B78a * 150.5-161.5*0.
£>J® * 0.8291
nj* * 1.4266
Surface Tension at 25*0. * 28.50 dynes
(20) 2,2-Dimethylpentano1-3 (125)
By the Grignard reaction using tert*-butyl chloride (108)

and prop!onaIdehyde•
Yield * 22 per cent
^V6« * 155-X58°C.
Ill* Condensation of the Secondary Aliphatic Alcohols with
feenzene*
''
~.
In a dry, one liter, three neck, flask equipped with
a mercury sealed stirrer, dropping funnel and calcium
chloride tube, and inlet tube were placed 50 grams of alumi­
num chloride (C.P. anhydrous) and 400 ml* of ben sens (anhy­
drous, thiophene-free) • The stirrer was set in motion and
hydrogen chloride gas was bubbled through the reaction mix­
ture at such a rate that the bubbles could just be counted*
The reaction mixture was then surrounded by an Ice bath and
after 10-15 minutes, a solution of one-half mole of the
alcohol in 50 ml. of benzene was added dropwise and with
stirring over a period of about one and a half hours*
Stirring was continued for about one hour longer and then
the reaction mixture was permitted to s tand for about eight
hours*

In the ease of the straight-chain alcohols, the

reaction mixture waa then refluxed for eight hours more, the
dropping funnel beldg
calcium chloride tube*

replaced by a reflux condenser and
An oil bath was used in the heating

and hydrogen chloride gas was kept bubbling through the
reaction mixture*
The reaction mixture was then poured onto ice and con­
centrated hydrochloric acid was added to dissolve any basic
aluminum salts that separated*

The resulting mixture was

shaken well in a separatory funnel, the aqueous layer

29.
separated and extracted twice with small amounts of benzene
or ether.

The combined benzene or benzene-ether extracts

were washed once with water, then with a dilute sodium bi­
carbonate solution and finally once more with water*
After drying over anhydrous sodium sulfate, the benzene
and ether were removed by vacuum distillation.

The residual

liquid was distilled at atmospheric pressure using a short
column.
(1) Condensation of Propanol-2 with benzene.
Yield of monoalkyXbenzene * 71 per cent
By** « 151°C.
j>J® * 0.8600
np* » 1.4956, n§® * 1.4858
Surface Tension at 25°C* = 27*78 dynes (Drop Weight)
= 29.28 dynes (Du Souy)
P&rachor « 320.6 (Drop Weight), calculated* * 319.8
* 324*8 (Du Kouy)

xAll calculated values are those of the expected
secondary monoalkyIbenzene. The molecular volumes were cal­
culated by the formulae developed by Kauffmann for unbranched
homologues of benzene.
Kauffmann, ftBezlehungen Zwischen
Physikalischen Eigensehaften und Chemlsher Konstitution, ”
Verlag F. Enke, 8tuttgart, Germany, 1920, p. 98 • Molecular
volumes were corrected to 20°C. by subtracting 0*11 for
each degree above this temperature.
Parachor values are calculated using the constants
of Mumford and Phillips (J. Chem. Soc. 33, 2112 (1929)).
Decrements of 3.0 for branched groups of the type -GBK*
and double this value for the group -CRa were subtracted.
A similar decrement was used for the attachment of an alkyl
group to a benzene ring*
Indices of refraction were observed using an Abbe refractometer. Molecular refractions were calculated from
the Lorentz-Lorenz formula.

30.,
Molecular Refraction « 40*28, calculated * 40*24
Molecular Volume at 20°C» * 138*88, calculated ~ 139*41
Monoaeetamino derivative, M*Ft.335 105°C*
Diacetamino derivative, M.Pt* * 215-214*0.
(2) Condensation of Butanol-2 with benzene*
Yield of monoalkylbenzene = 81 per cent
B78a * 171°C.
Dj® « 0*8597
nj* * 1*4936, nj® * 1.4878
Surface Tension at 25°C* ® 28.20 dynes (Drop Weight)
« 29*40 dynes (Du Mouy)
Parachor * 359*5 (Drop Weight), calculated * 359*4
* 365*2 (Du Nouy)
Molecular Refraction * 44*93, calculated 44*85
Molecular Volume at 20°C. * 155*14, calculated « 155*68
Monoacetamino derivative, M«Pfc. *» 126°0*
(3) Condensation of Pentanol-2 with benzene*
Yield of monoalkylbenzene * 83 per cent
B7ea * 190®C.
aG = 88*89 per cent, H » 10*98 per cent
D|» a 0.8599
n|4 ** 1.4921, nj* » 1*4867
Surface Tension at 25°C* * 28*49 dynes (Drop Weight)
* 29.72 dynes (Du Nouy)
Calculated, C * 89.12 per cent
H * 10*88 per cent

31.
Parachor * 397.0 (Drop Weight, calculated « 399.4
* 402.2 (Du Houy)
Molecular Refraction * 49.19, calculated * 49.45
Molecular Volume at 20°C. » 171.32, calculated * 171.95
Monoacetamluo derivative, M.Pt. * 118-119*0•
Alpha n&pkthy lure thane, M.Pt. « 99-99.S^C.
(4) Condensation of Pentanol-3 with benzene.
Yield of monoalkylbenzene « 65 per cent
B707 « 189-190.5*C.
aC * 88.97 per cent, H = 10.83 per cent
d J*

« 0.8605

nj4 * 1.4932, n®* * 1.4877
Surface Tension at 2S*C. » 28.51 dynes (Drop Weight)
* 29.65 dynes (Du Nouy)
Parachor 88 397.4 (Drop Weight), calculated = 399.4
* 401.7 (Du ilouy)
Molecular Refraction ** 49.57, calculated « 49.45
Molecular Volume at 20°C. « 171.17, calculated * 171.95
Monoacetamino derivative, M.Pt. * 121-122°C.
Alpha naphthylurethane, M •Pt • » 97.5-98.5°C.
(5) Condensation of 2-lethylbutanol-S with benzene.
Yield of monoalkylbenzene =* 54 per cent
B7ao 33 188.5-190*0.
aC » 89.23 per cent, H » 10.79 per cent
d J*

« 0.8634

nj4 « 1.4952, ng* * 1.4908

32.
Surface Tension at 25®C. ** 28.60 dynes (Drop Weight)
» 29.92 dynes (Du Nouy)
Parachor * 394.6 (Drop Weight), calculated = 396.4
« 399.1 (Du Mouy)
Molecular Refraction « 49.38, calculated * 49.45
Molecular Volume * 171.95, calculated « 169.63
at 20°C*
Monoacetamino derivative, M.Pt. «= 137-138°C.
Para hydroxy derivative, M.Pt. * 89-90°G.
Alpha naphthylurethane, M.Pt. * 125-126°C.
(6) Condensation of Hexanol-2 with benzene
Yield of monoalkylbenzene * 72 per cent
BTe* * 208-210*0.
* 88.86 per cent, B *» 11.06 per cent
Dj* * 0.8608
n*4 a 1.4909, n*® * 1.4866
Surface Tension at 25°C. « 28.79 dynes (Drop Weight)
« 30*16 dynes (Du Mouy)
Paraehor = 436.3 (Drop Weight), calculated = 439.4
* 441.5 (Du Houy)
Molecular Refraction = 54.15, calculated = 54.05
Molecular Volume at 20°C* - 187.33, calculated = 188.22
Alpha naphthylure thane, M.Pt. * 95-96.5°G.
(7) Condensation of 2-Methylpentanol-4 with benzene.

^calculated, C « 88.82 per cent
H * 11.18 per cent

33.
Yield of monoalkylbenzene = 50 per cent
BTeo = 205-206*0*
*>C « 38*53 per cent, E = 11*31 per cent
Bj® * 0*8754
nj* * 1.4988, ng* * 1*4932
Surface Tension at 25®G* » 28*79 dynes (Drop height)
» 29.84 dynes (Du Sony)
Parachor « 431*6 (Drop Weight), calculated * 436*4
= 432*9 (Du Houy)
Molecular Refraction * 53*85, calculated *= 54*05
Molecular Volume at 20°C* * 184*20, calculated * 188*22
Alpha naphthylurethane, M.Pt. 55 103-112° C*
(8) Condensation of Hexsnol-o uith benzene.
Yield of monoalkylbenzene » 65 per cent
BTa0 * 209-211*0.
bC * 88*67 per cent, H =* 11*11 per cent
Dj* » 0.8580
Up* =* 1*4894, n£® ~ 1*4845
Surface Tension at 25°C. » 28*93 dynas {Drop Weight)
« 29.84 dynes (Du Houy)
Parachor * 438*1 (Drop Weight), calculated » 439*4
W 441.7 (Du Houy)
Molecular Refraction 88 54.11, calculated * 54*05
Molecular Volume at 20°C. * 187*93, calculated * 188*22
Alpha naphtiiylurethane, M.Pt* * 95-96°C.
(9) Condensation of 3-M©thylpentanol-2 with benzene
Yield of monoalkylbenzene - 56 per cent

34.
&Ta, * 207-208*0#
« 89*17 per cent, H * 10*94 per cent
Djc *■ 0.8760
ag€ * 1.4990, ng* * 1.4951
Surface Tension at 25°C. » 29*28 dynes {Drop Weight)
* 30*55 dynes (Du Houy)
Parachor = 430*6 (Drop Weight), calculated * 436*4
* 435*1 (Du Houy)
Molecular Refraction = 53*99, calculated = 54*04
Molecular Volume at 20°C. * 184.07, calculated « 188.22
Alpha naphthylurethane, M.Pt* * 103.5=105.5°C.
(10) Condensation of 2-M©thylpentanol-3 with benzene.
Yield of monoalkylbenzene * 66 per cent
B7e4 * 208-209*0#
bG « 89*00 per cent, H * 11*04 per cent
Dj* * 0.8702
n£* * 1.4947, ng* • 1.4900
Surface Tension at 25°C. = 28*96 dynes (Drop Weight)
* 29.78 dynes (Du Houy)
Parachor * 432*3 (Drop Weight), calculated * 436.4
* 435.3 (Du Houy)
Molecular Refraction * 33*88, calculated 54.05
Molecular Volume at 20*G* * 185*31, calculated * 188*22
Alpha naphthylurethane, M.Pt* = 123.5-125*0*
(11) Condensation of 2,2-Dime thylbutanol-3 with benzene*
Yield of monoalkylbenzene = 62 per cent

35.
BT0O * 205-207°C.
*>0® 68*96 pep cent, B * 10*99 pep cent
Dj® « 0.8763
nj4 a 1.4988,

« 1.4942

Surface Tension at 25°C. ® 28.92 dynes (Drop Weight)
* 30.16 (Du Houy)
Parachor « 429*1 (Drop Weight), calculated * 433.4
« 433*6 (Du Houy)
Molecular Kefraetion * 53.89, calculated 54*05
Molecular Volume at 20® G. * 184.01, calculated * 188.22
Alpha naphthylurethane, M.Pt* = 109-110°C.
(12) Condensation of H©ptanol-2 with benzene*
field of monoalkylbenzene * 72 per cent
B70e ® 226-227®C.
cC « 88.47 per cent, 1 ® 11.40 per cent
Dj® * 0.8585
n£* « 1.4882, nj* » 1.4837
Surface Tension at 25®C. * 28.94 dynes (Drop Weight)
* 29.72 dynes (Du Houy)
Parachor * 475.9 (Drop Weight), calculated * 479.4
® 479.1 (Du Houy)
Molecular Kefraetion » 58.68, calculated ® 58.66
Molecular Volume at 20*0. ® 204*47, c&leulated * 204.49
Alpha naphthylurethane, M.Pt. = 94.5-96.5°C.
ccalculated, C » 88.56 per cent
H « 11.44 per cent

36.
(13) Condensation of Eeptanol-3 with benzene
Yield of monoalkylbenzene » 67 per cent
BT8* * 227-228*0.
cC * 88.66 per cent, E « 11.69 per cent
Dj* ® 0.8669
nj* * 1.4873, eg* « 1.4828
Surface tension at 25*0. » 28.73 dynes (Drop Weight)
* 30*03 (Du Houy)
Parachor « 475.9 (Drop Weight), calculated = 479.4
® 481.2 (Du Houy)
Molecular Kefraetion « 68.69, calculated « 58.66
Molecular Volume at 20 *C. ® 204.45, calculated * 204.49
Alpha naphthylurethane, IC.Pt. » 95.5-97.5*0.
(14) Condensation of Heptanol-4 with benzene.
Yield of monoalkylbenzene = 63 per cent
Bt#* * 226-229*0.
®G « 88.29 per cent, K * 11.62 per cent
Dj* ® 0*8613
n§* * 1.4899, n£® = 1.4847
Surface tension at 25*0. * 29.03 dynes (Drop Weight)
* 29.78 dynes (Du Houy)
Parachor * 474.7 (Drop Weight), calculated « 479.4
* 477.8 (Du Houy)
ISoleeular Kefraetion * 58.59, calculated » 58.66
Molecular Volume at 20*G. * 203.38, calculated “ 204.49
Alpha naphthylurethane, M.Pt. « 93.5-94*0.

37.
(15) Condensation of 2-Kethylhexanol-3 with benzene.
Yield of monoalkylbenzene * 62 per cent
Brea * 225-226®C.
CG » 88.19 per cent, H *» 11.56 per cent
dJ*

* 0.8688

n£* » 1.4935, n£* * 1.4893
Surface Tension at 25°C. » 29.08 dynes (Drop Weight)
a 30.09 dynes (Du Houy)
Parachor » 470.9 (Drop height)# calculated * 476.4
* 474*9 (Du Houy)
Molecular Refraction * 58.55, calculated « 58.65
Molecular Volume at 25°C. * 201.65, calculated * 204.49
Alpha naphthylurethane, M.Pt. * 125-127®C.
(16) Condensation of 3-®ethylhexanol~4 with benzene*
Yield of monoalkylbenzene ** 60 per cent
B t «# * 224-226®C.
eC * 88.27 per cent, H * 11.63 per cent
Dj* * 0.8727
n£* « 1.4952, n£* * 1.4913
Surface Tension at 25®C. « 29.88 dynes (Drop Weight)
* 30.91 dynes (Du Kouy)
Parachor « 470*0 (Drop Weight), calculated ® 476.4
= 476.0 (Du Kouy)
Molecular Refraction * 58.49, calculated * 58.66
Molecular Volume at 20°C* = 20C.75, calculated = 204.49
Alpha naphthylurethane, M.Pt. « 101-103°C.

38*
(17) Condensation of 2-Methylhexanol-4 with benzene*
Yield of monoalkylbenzene * 54 per cent
D7ea ® 224*225*0.
cC • 88.13 pet? cent, H * 11*40 per cent
b J*

« 0*8654

n£* * 1*4911, np* a 1*4873
Surface lension at 25°C* » 28*74 dynes (Crop Weight)
a 29*84 dynes (Du Houy)
Parachor a 471*3 (Drop Weight), calculated = 476.4
« 475*8 (Du Houy)
Molecular Refraction a 58*58* calculated a 58*66
Molecular Volume at 20°C* » 202*45* calculated » 204*49
Alpha naphthylurethane, M.Pt* * 119-121°C*
(18) Condensation of &»Hethylhexa&ol«5 with benzene
Yield of monoalkylbenzene * 44 per cent
B7«e * 223~226°C.
cC a 88*43 per cent* H » 11.31 per cent
Dj* * 0,8777
* 1*4973, ng® * 1.4929
Surface Tension at 25°G. » 29.06 dynes (Drop Weight)
* 29*97 dynes (Du Houy)
Parachor » 466*0 (Drop Weight), calculated * 476*4
* 469*0 (Du Houy)
Molecular Refraction « 58.33* calculated * 58.66
Molecular Volume at 20°C« * 199^59* calculated s 204*49
Alpha naphthylurethane* M.Pt* *= 119-121°C.
(19) Condensation of 3-Hethylhexanol-2 with benzene*

39*
Yield of monoalkylbenzene ** 36 per cent
©*«* * 224-226.5*0.
®C » ©8*99 per cent, H * 11*32 per cent
Dj* a 9*8767
n§* » 1*4976, n£® « 1*4939
Surface Tension at 25°G* » 29*14 dynes (Drop Weight)
* 30*09 dynes (Du Houy)
Parachor » 466*8 (Drop Weight), calculated * 476*‘4
** 470*6 (Du Houy)
Molecular Refraction = 58*48, calculated » 58*66
Molecular Volume at 20°C* = 199*82, calculated « 204*49
Alpha naphthylurethane, M.Pt* * 106-108*0*
(20) Condensation of 2,2-Dimethylpentanol-3 with benzene
Yield of monoalkylbenzene = 58 per cent
Brea * 221-223°C.
cC » 88*63 per cent, H «* 11*30 per cent
Dj* * 0.8720
n£4 * 1*4947, a|® * 1*4912
Surface Tension at 25°C* * 28*67 dynes (Drop Weight)
* 29*65 dynes (Du Houy)
Parachor = 467*5 (Drop Weight), calculated « 473.4
« 471.4 (Du Houy)
Molecular Refraction * 58*53, calculated = 58*66
Molecular Volume at 20°C* = 200*90, calculated * 204*49
Alpha naphthylurethane, 2J*Pt. * 114-115°C*

40.
If* Derivatives

(1) Acetamino Derivatives
These compounds were prepared by the method of
Ipatieff and Schmerling (126-127)*
(2) Alpha naphthylurethane a
These compounds were prepared by a modification
of the methods given in Fisher’s text (104) and is almost
the same as Malherbe’s procedure used by Guile (70)*
(a) Preparation of the mononitro alkylbenzenes*
To one-tenth of a stole of alkylbenzene was added
dropwise and with shaking, twenty four ml* of a mixture
consisting of concentrated sulfuric and nitric acids in
equal parts by volume.

The temperature of the reaction

mixture was kept below 50°C. by immersion In an ice bath
when this temperature was approached. The reaction mixture
was then placed in a water bath at 50°G. and kept there,
with frequent shaking for one-half to two hours.
then poured onto ice and extracted with ether.

It was
The ether

layer was washed three times with a saturated salt solution
and the ether removed on a steam bath.

The residue was

distilled in vacuo using a hywac oil pump.
(b) Reduction of the nitro compound to the amine.
To the nitro compound, placed in a flask fitted
with a reflux condenser was added 30 grams of mossy tin
for each one-tenth mole of compound.

Eighty ml. of con­

centrated hydrochloric acid (for each 1/10 mole of compound)
Motet

The para position of the entering nitro group has been
well established by previous workers In this laboratory
(2,98)*

41.
was added in small portions through the mouth of the con­
denser, the flask being shaken after each addition.

After

the vigorous reaction had subsided, the flask was heated
on a steam bath for one-half hour*
lee and sufficient concentrated sodium hydroxide to
dissolve most of the tin hydroxide that precipitated were
then added*

The solution was then extracted three times

with ether and the combined ether extracts washed til clear
with a saturated salt solution.

The ether was evaporated

on a steam bath and the residue distilled under reduced
pressure*
(c) Conversion of the amine to phenol*
For each one-tenth mole of amine, placed in a beaker,
was added a hot solution of 11 ml* of concentrated sulfuric
acid dissolved in 50 ml* of water.

The solution was stirred

well with a thermometer and placed in an ice-salt bath*

lee

was added to the solution and when the temperature of the
latter had dropped below zero degrees centigrade, a saturated
aqueous solution of eight grams of sodium nitrite was added
slowly and with stirring*

The temperature was maintained

at or below zero degrees centigrade during this addition*
When all the sodium nitrite had been added, the solution
was stirred until all the suspended solid amine sulfate
dissolved*

When all, or nearly all, the solid had dissolved,

two grams of urea {for each 1/10 mole of compound), dissolved
in a minimum of water, was slowly added.

The solution was

then permitted to stand for about ten minutes and then

42.
steam-distilled by allowing it to drop slowly on a boiling,
dilute, sulfuric acid solution through which steam was
being passed.

The reaction mixture was steam-distilled

until no more phenol came over.

The distillate was saturated

with salt, cooled, and extracted twice with ether.

The

ether was evaporated on a steam bath and the residue dis­
tilled in vacuo.
(d) Preparation of the Alpha naphthylurethane of the
phenol (128)•
1-2 grams of the phenol was treated with half its
volume of Alpha naphthylisocyanate.

The reaction was

catalyzed by the addition of a few drops of an anhydrous
ether solution of trimethyl amine (kept anhydrous over
sodium sulfate).

The mixture was shaken well, stoppered

with a cork to which was attached a drying-, tube, and
placed on a steam bath for five to fifteen minutes.

On

cooling, the solution solidified completely and the solid
was recrystallized to constant melting point from skellysolve
(B .Ft. 60-70 degrees Centigrade)(a higher boiling petroleum
ether portion) or ligroin*

43.
Table II
Para Nitro Derivatives of the Monoalkylbenzenes
Alcohol Condensed
with Benzene

B. Ft. of
Nitro Compd.

At. Pres

Pentanol-2

112-114®C.

2 mm.

Pentanol-3

111-117®C.

2 mm.

2-JSethy Ibut anol-5

113-118°G*

2 mm.

Eexanol-2

133-141°C*

3 mm.

2-Methylpentanol-4

I34-138®C.

3 mm.

Hexanol-5

122*5-124®C.

2 mm.

3-lfethyIpent anol-2

124-127®C.

2 mm.

2-MethyIpentanol-3

123.5-127®C.

2 mm*

2 ,2-Bime thylbutanol-3x

117-123®C.

2 mm.

Heptanol-2

154-156®C.

3 mm.

Heptanol-3

143-149®C.

3 mm.

Heptanol-4

146-150®G.

3 M*

2-Methylhexanol-3

140-146®C.

3 mm.

3-Methylhexanol-4

143-148®C.

3 mm.

2-Methylhexanol-4

136-143®0.

3 mm.

2-Methylhexanol-5

139-142®C.

3 mm.

3-M ethylhe.nanol-2

155-139°C*

3 mm.

2,2-DimethyIpent ano1-3

159-141®C.

3 mm.

*Anal. for Nitrogen;

Pound, N = 6.68 per cent
Calculated, N = 6*73 per cent

Table III
Para Amino Derivatives of the MonoalkyIbenzenes
Alcohol Condensed
with benzene

B. Pt. of
Amine

Pressure

Pentanol-2

101-102*0.

2 mm.

Pentanol-3

103-105.5*0.

2 mm.

2-Methylbutanol-3

99-103*0.

2 mm*

Hexanol-3

111-114*0.

2 mm#

2-SSethyIpent anol-4

124*0.

5 mm.

Hexanol-3

121.5*0.

3 mm.

3-Methylpentanol-2

112-113*0.

2 mm.

2-Methylpentanol-3

111-113*0.

2 mm.

2.2-Dlmethylbutanol-3x

115-118*0.

2 mm.

Heptanol-2

124-127*0.

2 mm.

Heptanol-3

124-126*0.

2 mm*

Heptanol-4

129-130*0.

2 mm.

2-Methylhexanol-3

127-129*0.

2 mm.

3-Methylhexanol-4

124-126*0.

2 mm.

2-Nethylhexanol-4

120-124*0.

2 mm.

2-Methylhexanol-5

123-127*0.

2 nun.

3-Methylhexanol-2

120-125*0.

2 mm.

2.2-Dimethylpentano1-3

120-126*0.

2 mm.

XAnal* for Nitrogen:

Pound,! = 7*74 per cent
Calculated, N * 7.87 per cent

45
Table I?
Para Hydroxy Derivatives of the MonoalkyIbenzenes
Alcohol Condensed
with Bensene

B. Pt. of
Phenol

Pressure

Pentanol-2

100-104*0.

2 mm.

Pentanol-3

100*0.

2 mm*

2-Methylbutanol-5

110-111*0.

3 mm .

Hexanol-2

108-113*0.

2 mm.

2-Methylpenfcanol-4

115-119*0.

3 mm.

Hexanol-3

117-119*0.

3 mm.

3- Methy Ipent ano1*2

117-121*0.

3 mm.

2-Methylpentanol-S

116-119*0.

3 mm.

2 ,2-DimethyIbutanol-S*

115-118?G*

3 mm.

He piano1-2

120-122*0.

2 mm.

Heptanol-3

125-127*0.

2 mm.

Heptanol-4

117-121*0.

2 mm.

2-Mefcfcylhexanol-3

123-127*0.

3 mm.

3-Methylhexanol-4

128-131*0.

3 mm.

2-Methylhexanol-4

122-129*0.

3 mm.

2-Me thylhexanol-5

123-126*0.

3 mm.

3-Methylhexanol-2

121-125*0.

3 mm.

2 ,2-Dime thyipentano 1-3

131-133*0.

3 mm.

xAnal. for C and H:

M.Pt.

89-90°d

122*0 .

Found, C * 80*65 per cent, H * 10.35 per cent
Calculated, 0 =* 80.85 per cent,
H * 10.18 per cent

46.

Table V
Alpha H aphthylure thanes from the Monoalkylbenzene a
Alcohol Condensed
with Benzene

M. Pt. of
Urethane

% H

Pentanol-2

99-99.5*0.

4.13*

Pentanol-3

97.5-99.5*0.

4.18®*

2-Methylbutanol-3

125-126.5*0.

4.17®

Hexanol-2

96-96.5*0.

3.99b

2-Methylpentan©l-4

108-112*0.

S.97b

Hexanol-3

95-96*0.

4*Q3b

3~Methylpentanol~2

103-105.5*0.

3.99b

2-Methylpentanol-3

123.5-125°C.

4.00^

2, 2-DimethyIbutanol-3

109-110*0.

5.98b

Heptanol-2

94.5-96.5*0.

3.82®

Heptanol-3

95.5-97.5*0.

3.86®

Heptanol-4

93.5-94*0.

3.82®

2-Me thylhexanol-3

125-126*0.

3.83®

3-Methylhexanol-4

101-103*0.

3.87®

2-Methylhexanol-4

119-121*0.

3.79®

2-Methylhexanol-5

119-121*0.

3.86®

3-MethyIhexano 1-2

106-108*0.

3.83®

2,2-Dimethylpentan©l-3

114-115*0.

3.79®

Calculated?

(a) H * 4.12 per cent
(b) H = 4.03 per cent
(c) 5 » 3.87 per cent

47.
V. Determination of the Nature of the Monoalkylbenzenes
The monoalkylbenzenes obtained in these condensations
may be divided roughly into three classes:
(a) pure monoalkylbenzenes obtained from the secondary
alcohol without rearrangement,
(b) tertiary alkylbenzenes, with the possibility of a
small amount of secondary alkylbenzene as impurity,
obtained from a secondary alcohol with branching
adjacent the hydroxyl group,
(c) mixtures of two or more alkylbenzene® obtained from
secondary alcohols which may or may not have branch­
ing in their molecules.
Two members of the first class, euraene and sec•-butylbenzene, were shown to be formed without rearrangement from
their corresponding secondary alcohols by comparison of
the melting points of their monoscetamino derivatives with
those in the literature (126-127).
The structure of the tertiary alkylbenzenes was proven
by converting these compounds to their corresponding para
hydroxy derivatives.

Alpha naphthylurethanes were prepared

from the latter and mixed melting points were taken with
the alpha naphthylurethanes prepared from the tertiary
alkylphenols obtained by previous workers in this laboratory
by the condensation of tertiary alcohols with phenol in
the presence of aluminum Chloride.

Curtis (99) prepared

the alpha naphthylurethanes of the tertiary hexyl phenols

48.

condensed by Haleb (2)•

The author prepared the alpha

naphthylure thanes of Hsieh’a para tert.-amylphenol and
Hedrick1s me thy lethy1-n-propyl-para-hydroxyphenylrae thane,
dime thy1-n-butyl-pa ra-hydroxyphenylme thane and methylethyl1sopropyl-para-hydroxyphenylme thane. The last three deriva­
tives were found to have higher melting points than those
reported by Hedrick and are listed, together with the afore­
mentioned data in Tables VI

and VIII.

To get some idea of the nature of those alkyibenzenes
which were mixtures, the monoalkyIbenzenes which would have
been obtained from the secondary alcohols if no rearrange­
ment occurred, were prepared by independent synthesis.
This was done by a modification of the method of Klages (37)
which consisted of treating an alkyl Grlgnard compound with
aeetophenone or its homologues, forming a tertiary alcohol.
The alcohol was reduced to the hydrocarbon by first forming
f

an olefin by splitting out water, and then reducing the
unsaturated compound with sodium and absolute ethyl alcohol.
This procedure {Procedure I) gave a pure alkylbenzene which
was converted to the para hydroxy derivative by the procedure
already outlined (see Section IV under Experimental)* The
alpha naphthy lure thanes of these phenols were then prepared
fmri compared with those obtained in the condensation, mixed
melting points being performed wherever feasible.

A more

convenient method (Procedure II) for obtaining the alpha
naph thylure thanes of the para hydroxyphenylalkanes consisted
in using the para methoxy derivatives of aeetophenone and

49.
its homologu.es, propiophenone and butyrophenone• These
compounds, when treated with the Grignard reagent, reduced
and demethylated, gave the alkylphenol directly, avoiding
the lenghthy nitration, reduction and diazotization scheme.
Procedure I.
The Grignard reagent was prepared by the technique
previously described (Section II under Experimental).

The

crude product was converted into the olefin, without isolat­
ing the tertiary alcohol formed, by refluxing, using a
Dean and Stark moisture trap (129) until no more water
collected.

This usually took but a few minutes.

The

product was then distilled.
The unsaturated compound was reduced by dissolving
0.25 mole of olefin in 375 ml* of absolute ethyl aleohol and
treating the boiling solution with 40 grams of sodium,
added in several large pieces at intervals#

The solution

was refluxed gently on a steam bath, using anhydrous pre­
cautions, during the treatment with sodium.

When all the

sodium had dissolved, water was added in great excess, and
the mixture extracted three times with ether.

The ether

layer was then washed free of alcohol repeatedly with a
saturated salt solution until its volume remained constant.
The ether was then removed on a steam bath and the residue,
after cooling, shaken thoroughly with a saturated potassium
permanganate solution.

The excess permanganate was then

reduced by the addition of solid sodium bisulfite and the
alkylbensene extracted with ether.

After evaporation of

50#

the ether on a steam hath, the residue was distilled at
atmospheric pressure*

The slkylbenzene was then converted

to the phenol by the procedure in Section I¥ under Experi­
mental and the alpha naphthy lurethane of the latter was
prepared*
(1) 3 -Phanylpentane (39), B?** * 1S9-191°C*
Prepared from dIethyIpheny1carbino 1 (prepared by Hughes
(97))*
(a) Intermediate unsaturated compound (39), B7«.i * 199-2O10C.
(b) Para Hi taro derivative, B8 « 11Q-11S°C.
Founds

Hitrogen * 7*18 per cent

Calculated?

Nitrogen * 7*25 per cent

(c) Para Amino derivative, B® « 107-116°C*
Founds

Nitrogen » 8*43 per cent

Calculated?

Nitrogen « 8*58 per cent

(d) Para Hydros derivative, B* * 108-117°C*
W.Pt. * 75.5®C.

This compound has been reported as

melting at 79-S0°C* (133).
(e) Monoaeetamlno derivative of the alkylbenzene
M.Pt. » 144°C.

Ipatieff and Schmerling (127) report

a melting point of 145-1460C.
(f) Alpha naphthy litrethane, M.Pt.« 114°C*
Found:

Nitrogen « 4*07 per cent

Calculated:

Nitrogen « 4.12 per cent

(2) 2-Phenylpentane (37), B7es ~ 191-195°C*
Prepared from propyl bromide and aeetophenone.
(a) Intermediate unsaturated compound (37)
BTea * 202-204°C.

(b) Para NItro derivative, Bs * 112-118°C.
Found:

Nitrogen * 7*21 per cent

Calculated:

Nitrogen » 7.25 per cent

(c) Para Amino derivative, Ba « 1Q1-1Q4®C.
Found?

Nitrogen « 8.49 per cent

Calculated:

Nitrogen * 8*58 per Gent

(d) Para Hydroxy derivative, 8a * 101°C.
Found?

C * 80*83 per cent, B * 10*33 per cent

Calculated:

C * 81*19 per cent, H * 10.48 per cent

(e) Alpha naphthylurethane, M.Ffc. » 10C)-101°C.
Found:

litre gen * 4*09 per cent

Calculated?

Nitrogen « 4*12 per cent

(3) 2-Phenylhexane (43), B737 • 210°C.
Prepared from n-butyl bromide and aeetophenone*
(a) Intermediate olefin, B7S7 « 219-224°C*
(b) Para NItro derivative, B* * 120-128°C*
Found: Nitrogen * 6.62 per cent
Calculated;

Nitrogen « 6*73 per cent

(c) Para Asdno derivative, B* » 112~116®C.
Found?

Hitrogen « 7.78 per cent

Calculated:

Nitrogen * 7.82 per cent

(d) Para Hydroxy derivative (134), Ba 55 110-112°C.
(e) Alpha naphthylurethane, M.Pt. ** 108-109°C.
Found:

Nitrogen = 3.98 per cent

Calculated:

Nitrogen =4.03 per cent

(4) 4-Phenylheptane, B76o 35 221-224°C.
Prepared from n-propyl bromide and ethyl benzoate.

52 o

Founds

C s= 88*37 per cent, H * 11*51 per cent

Calculated?

C * 88*56 per cent, H * 11*44 per cent

(a) Intermediate olefin, B0 = 80-95°C.
(b) Para NItro derivative, Ba = 140-143®C«
Founds

Nitrogen * 6*29 $er cent

Calculated?

Nitrogen = 6*33 per cent

(c) Para Amino derivative, Bs * 128-132°C*
Founds

Nitrogen ** 7*26 per cent

Calculatedi

Nitrogen * 7*32 per cent

(d) Para Hydroxy derivative, Ba = 121-123°C*
Found:

C « 80*78 per cent, H ** 10*27 per cent

Calculated?

C * 81*19 per cent, H = 10.48 per cent

(e) Alpha naphthylurethane, M.Pt. * 104-105®C.
Founds

Nitrogen * 3*88 per cent

Calculated?

Nitrogen * 3.87 per cent

(5) 2-Me thy1-4-phenyIp@n tane (40), B736 ~ 197-198°C*
Prepared fro® isobutyl bromide and aeetophenone•
(a) Intermediate olefin (40), Bra& 38 213-225®C#
(b) Para Witro derivative, Bs = 132®C*
Found:

Nitrogen 38 6*66 per cent

Calculated:

Nitrogen =6*73 per cent

(c) Para Amino derivative, Ba 3=8 113~115®G*
Found:

Nitrogen =7*83 per cent

Calculated:

Nitrogen = 7.87 per cent

(d) Para Hydroxy derivative, Ba = 109-110®C*
Found:

C = 80.37 per cent, H = 10.18 per cent

53.
Calculated?

C ■ 80*85 per cent, B = 10.18 per cent

(e) Alpha naphthylurethane, H.Pt* * 107°G*
Found:

Nitrogen = 3.96 per cent

Calculated:

Nitrogen * 4.03 per cent

Procedure II.
The method was the same as the proceeding but instead
of aeetophenone, para methoxyacetophenone (25), para methoxypropiophenone (24,130), and para methoxybutyrophenone
were used and the para hydroxyphenylalkanes prepared with­
out preparing the intermediary products.

After the reduc­

tion with sodium and alcohol, the product was demethylated
without Isolating the ether*

In the hydrolysis of the ether,

10 grams of the product was re fluxed with 50 grams of phenol
and 100 ml. of 48 per cent hydrobromie acid'for 4 hours
(131).

The mixture wee then extracted with ether, the

ethereal layer washed three times with water to remove any
acid and the ether removed on a steam bath.

The product

was then vacuum-distilled, discarding the lower boiling
phenol.

The alpha naph thylure thane of the phenol was then

prepared.
(1)

3 -Para

bydroxyphenylhexane, B4 = 133®C.

Prepared from n-propyl bromide and para methoxypropiophenone.
Found:

C * 80*67 per cent, H = 10.11 per cent

Calculated:

C « 80*85 per cent, H « 10.18 per cent

Alpha naph.thylurethane , M.Pt. = 95-95. 5°C*
Found:

Nitrogen =3*99 per cent

Calculated:

Nitrogen = 4.03 per cent

54.
(2) 5-Para hydroxyphenylheptane, B® * 117®C.
Prepared from n-butyl bromide and para methoxypropiophenone.
Found:

C = 81.07 per cent, H = 10*31 per cent

Calculated;

C = 81.19 per cent, H « 10.48 per cent

Alpha naphthylurethane, M.Pt* * 100®C.
Found:

Nitrogen = 3.79 per cent

Calculated:

Nitrogen =3.87 per cent

(3) 2,2-Dimethyl-3-para hy&roxyphenylpentone, B® « 108®C.
Prepared from tert.-butyl chloride and para methoxypropiophenone•
Found;

C *= 80.87 per cent, H » 10.64 per cent

Calculated;

C = 81*19 per cent, H * 10.48 per cent

Alpha naphthyluro thane, M.Pt* • 118-119®C.
Found;

Nitrogen = 3*82 per cent

Calculated;

Nitrogen * 3.87 per cent

(4) 2-Methy1-4-para hydroxyphenylhexan©, B® ■ 111®C.
Prepared from Isobutyl bromide and para methoxypropiophenone.
Found:

C » 81.49 per cent, & * 10.29 per cent

Calculated:

C * 81*19 per cent, H * 10.48 per cent

Alpha naphthylurethane, M.Pt. * 117-117.5®C*
Found:

Nitrogen « 5.81 per cent

Calculated:
(5 )

Nitrogen * 3.87 per cent

3 -Methyl-2-para

hydroxyphenylpent&ne,

B3

=

120-123.5°C.

Prepared from sec.-butyl bromide and para methoxyacoto­
phonene.

55.
Found?

C « 80*71 per cent, H = 9*99 per cent

Calculated:

C * 80.85 per cent, H « 10.18 per cent

Alpha naphthylure thane, M.Pt. * 10G-101°C*
Found?

Nitrogen * 3.95 per cent

Calculated?

Nitrogen * 4*03 per cent

(6) 2-Para hydroxyphenylheptane, B* = 140°C*
Prepared from n-amyl bromide and para methoxyacetophenone.
Found:

C ® 80*78 per cent, H = 10*53 per cent

Calculated:

C « 81*19 per cent, B = 10.48 per cent

Alpha naphthylurethane, M.Pt. * 115-116°C.
Found:

Nitrogen = 3*86 per cent

Calculated?

Nitrogen =3.87 per cent

(7) 2-Methyl-5- para hydroxyphenylhexane, Ba « 123.5°C*
Prepared from isoamyl bromide and para methoxyaeetophenone *
Found:

C = 80.79 per cent, B « 10.20 per cent

Calculated:

C = 81*19 per cent, H = 10.48 per cent

Alpha naphthylure thane, M.Pt* = 125°C.
Found?

Nitrogen = 3*81 per cent

Calcu3a ted?

Nitrogen = 3.87 per cent

(8) 3-Methy 1-2-para hydroxy phenylhexan©, Ba » 123-125°C.
Prepared from sec.-amyl chloride and para methoxyaeetophenone.
Founds

C * 80.77 per cent, H = 10.37 per cent

Calculated?

C = 81.19 per cent, H * 10.48 per cent

Alpha naphthy lurethane, M.Pt. = 110-111°C.

56.
Pound:

Mitrogen « 3*82 per cent

Calculated:

Kitrogen *3*87 per cent

(9) 2,2-Dimethyl-3-para hydroxyphenyl butane, B4 * 1£3°C*
M.Pt* * 120-121°C*
Prepared from tertiary butyl chloride and para methoxyac etophenone .
Found*

C * 80*94 per cent* B * 10*64 per cent

Calculated*

C * 81*19 per cent* H ** 10*48 per cent

57.

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61*
&XSGTJSSIOH
The results of this Investigation can be reconciled
with the catinoid mechanism (134) of Fridel-Crafts condensa­
tions or the olefin mechanism of McKenna and Sowa (67)*
Either path

would yield the same product, assuming the

addition of the phenyl group to be in accordance with
Markownlkoff*s rule.
This work is in direct contrast with the statement by
Ipatieff (72) that aluminum chloride causes no rearrangement
In the condensation of secondary alcohols with benzene.
He baaed this conclusion on only one reaction, the formation
of n-propylbenzene in the condensation of n-propyl alcohol
with benzene.

It is interesting, In this connection to

point out once again the work of Bowden (62) who found that
n-propyl esters formed n-propylbenzene while n-butyl esters
gave sec.-butylbenzene.

This work is in agreement with

that of the Author1s who used alcohols instead of esters.
In harmony with the present results is the work of
Esterdahl (98) who condensed the secondary amyl alcohols
with phenol in the presence of aluminum chloride.

With

either pentanol-2 or pentanol-3, he obtained a mixture of
the 2- and 3-para hydroxyphenylpentanes. With 2-methylbutanol-3 he, too, obtained rearrangement to the tert.amylaryl compound.
Ourtis* (99) work, also is in agreement with this work.
With hexanol-2 and hexanol-3, he obtained, in his condensations

62*
with phenol in the presence of aluminum chloride, mixtures
of the 2- and 3-para hydroxyphenylhexanes * With 2-methy1pentanol-5, he obtained the tertiary phenol, 2-methyl-2para hydroxyphenylpentane.

He, too, obtained a mixture

In the condensation of 2-methylpentanol-4, though the
composition of his mixture must be somewhat different from
that of the Author*s because the melting point of his alpha
naphthylure thane is a few degrees higher.

These results

are In agreement with those presented here where benzene
was used in place of phenol*
However, where Curtis got rearrangement to the tertiary
phenol In the case of 5-methylpentanol-2, the present work
yielded a mixture, probably of the secondary and tertiary
alkylbenzanes*

In addition, where Curtis got migration of

a methyl group and formation of a tertiary phenol, using
pinacolyl alcohol, the author obtained the sec.-alkylbenzene
with no rearrangement*x

This discrepancy probably is due

to the difference in reactivity of benzene and phenol in
condensations, each reacting by a different mechanism.
Although the temperature In the condensations run by
Curtis and Esterdahl was much higher than that in the present
work, this factor is not responsible for the difference in
results,

^hls was shown by condensing pentanol-3, 3-methyl-

pentanol-2, S-methylhexanol-2, 4-methylpentanol-2, 3,5dimothylbutanol-2, and 2,2-dimethylpentanol-3 with benzene
^Repetition of this reaction of Curtis* by the author, using
his conditions and reaetanta, gave the same product as he
obtained*

65c

at 50°C*

The alpha naphthylurethane s, prepared from the

alkylbenzenes obtained in these condensations, melted at
exactly the same temperatures as the urethanes from the
products obtained at the lower temperature*

This would

seem to indicate that, under the conditions of this experi­
ment, temperature plays no, or very little, role in deter­
mining the nature of the products*
Tsukervanik*s (100) condensation of isoamyl alcohol
with, phenol to give tertiary amyl phenol among other products,
would indicate that an olefin might be the intermediate In
the condensation*

In this case, however, the double bond,

if it were formed, shifted to a new position in order to
give the tertiary product*

^his migration of a double

bond during a condensation reaction has been observed by
Ipatieff (72), too, when sulfuric acid was the condensing
agent*

The migration may actually have occurred in some

of the condensations described in this paper.

Where branch­

ing occurs at a position remote from the earbinoi group,
some tert *-alky lben zene may be admixed with the mixture of
secondary alkylbenzenes*

The great similarity In the

physical and chemical properties of the alkylbenzenes ren­
ders remote the chances of separating the constituents of
these mixtures*
Using a different condensing agent, boron fluoride,
Toussaint and Hennion (71) came to the same conclusion when
they alkylated benzene with primary alcohols*
s e c * -alkylbenzenes

They obtained

only and concluded, "While the reaction

64*
mechanism is in doubt, the products are those which would
be formed by dehydration of the alcohol to olefin and addi­
tion of benzene according to Markownlkoff1s rule*"
Simons and Archer (58) dehydrated sec.-amyl alcohol
to get a mixture of pentene-1 and pentone-2 which was con­
densed with benzene, hydrogen fluoride acting as catalyst*
The monoacetamino derivative of the alkylbenzene mixture
which they obtained melted at 119-120°C*

In the present

work, pentanol-2 gave a product whose monoacetamino deriva­
tive melted at 118-119*0*, while the product from pentanol-3
had a monoacetamino derivative that melted at 121-122°C*
The pure alkylbenzenes, 2- and 5-phenylpentanes have monoace tamino derivatives that melt at 107°C. and 145-146°C*
respectively (127).

Simons and Archer concluded then that

their product was probably *a mixture of the beta and gamma
phenylpentanes *"
Ipatieff (72) has recently published an article which
contains a temperature-compositIon graph.

The melting

points of various mixtures of the 2- and 3-phenylpentanes
were plotted ag&inst the percentage composition of these two
isomers in the mixture*

The melting points of these mix­

tures were shown to lie between the values of the pure
alkylbenzenes.

This is In agreement with the work of Simons

and Archer as well as with that of the author.

According

to this graph, the alkylbenzene mixture from pentanol-2 and
benzene should consist of about 65 per cent of 2-phenylpentane and 35 per cent of 5-phenylpentane while the product

65.

from pentanol-3 should be 55 per cent 2-phenylpentane and
45 per cent 3-phenylpentane.
Ipatieff and coworkers (60) have shown that when benzene
Is alkylated, In the presence of sulfuric acid, with an
olefin having branching on one of the carbons In the double
bond, the product is exclusively the tertiary alkylbenzene.
This may not be so in the case of the alcohols having branch­
ing on the carbon adjacent the carblnol group; 3-methylpent anol-2 and 3-methylhexanol-2 gave mixtures of alkylben­
zenes whose alpha naphthylurethanes had melting points in­
termediate with those of the corresponding secondary and
tertiary compounds.

That all the tert.-alkylbenzenes ob­

tained by the author from secondary alcohols were admix id
with a little see.-alkylbenzene may be indicated by the re­
peated recrystallizations that were required before their
alpha naphthylurethanes gave constant melting points.

Fur­

thermore, the tertiary amylbenzene, prepared from 2,2?)
dimethylfeutattol-3 gave a monoacetamino derivative (M.Pt. «
137-138°C») that melted a few degrees lower than that re­
ported In the literature (60) for the monoacetamino deriva­
tive of synthetic tert.-amylbenzene (M.Pt. - 141-142°C.).
This was probably due to the presence of 3-methy 1-2-phenyl
butane in very small amounts * The latter*a monoacetamino
derivative, while possessing a higher melting point (M.Pt. =
147-148°C.), if present in small enough amounts, could act
as an Impurity and depress the melting point.

Though the

formation of this secondary product would not be in

66.

accordance with Markownikoff*s rule, it frequently happens
in addition reactions that a small amount of product is
formed In opposition to the rule.

The same may hold true

In the condensation reaction*
It has already been mentioned that In the case of
alcohols having extreme branching on the carbon atom adja­
cent the carblnol group, as In pinacolyl alcohol, migration
of a methyl group occurs In the condensation with phenol,
and a tertiary alkylphenol results.

This does not occur

when benzene is used instead of phenol*
replaces the hydroxy group.

The phenyl group

In the case of 2,2-dImeth.yl-

pentanol-3, a similar situation occurs, only here olefin
formation without any rearrangement of methyl groups is
possible.

The alpha naph thylure thane of the product has a

melting point of I14-115°C. while that of the urethane of
2, 5~dimethy1-3-para hydroxyphenylpentane melts at 124-125.5°C.
and that of 2,3-dlmethy1-2-para hydroxyphenylpentane melted
at 122-123°C., according to Hedrick*

It Is possible that

the product Is a mixture of these rearranged alkylbenzenes,
possibly admixed with one or both of the two possible sec.alkylbenzenes which could be formed without migration of a
methyl group*

In view of the fact that the lower homologue,

pinacolyl alcohol, underwent no change In condensing with
benzene, It seems more likely that the product consists of
the sec.-alkylbenzenes formed from an intermediary olefin,
namely 3~ and 4-phony 1-2,2-dimethylpentanea*
summarized by the following equations:

This may be

67
(1) Curtis1 Work

ch*
CHg - C - CH - CHCHg OH

+

C-H

“>

CHg CH®
CHg - C - C - CHS
CgHg H

(2) Author^ Work

GHg
(a) CHg - C - CH - CHg
CHg OH

+ CgHg

CHg
(b) CHg - C - CH * CH* - CHg
CH* OB

AlCX,■a

A1Q1--- %

CHg H
l 9 l
CHg - C - C - CHg
CHg CeHg

H
H
(CHg)g - C ~ C ~ C - CHS

CgHg
(CH*)* - C j ^ C H - CH* - CH* and (CH»)g - CH2~ CH - CH;
C.H
C A
a mixture (?)

68
SUMMARY
(1) Conditions have been worked out for condensing isopropyl
alcohol with benzene in the presence of aluminum chlor­
ide to give a good yield of cumene*
(2) Using these conditions, the secondary butyl, amyl, hexyl
and some secondary heptyl alcohols were condensed with
benzene*
(3) The alkylbenzenes obtained by these condensations were
converted to the corresponding para hydroxy derivatives
by nitration, reduction of the nitro group to amine, and
diazotlzation*

Alpha naphthylure thanes of the para

hydroxy compounds were also prepared as well as some
acetamlno derivatives*
(4) A number of pure sec .-alkylbenzenes and sec* -alkylphenols
were prepared by synthesis and their alpha naphthylurethanes made*
(5) By comparison of the melting points of the acetamino
derivatives of the alkylbenzenes, of the phenols and of
the alpha naphthylure thanes with those synthesized and
with those of the prepared tertiary alkylphenols, the
following facts have been established:
(a) Isopropyl alcohol, sec*-butyl alcohol and pinacolyl
alcohol gave the corresponding secondary alkyl­
benzenes in pure form.
(b) 2-Methylbutanol-3, 2-methylpentanol-5, 2-methylhexanol-3 and 3-methylhexanol-4 gave tertiary

69.
alkylbenzenes•
(c) The straight chain carbinols, as well as those hav­
ing a branched methyl group remote from the carbinol
group, gave mixtures of the secondary alkylbenzenes.
(d) 3-Methylpentancl-2 and 3-methylhexanol-2 gave mix­
tures consisting probably of the sec*- and tert.alkylbenzenes•

70.
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129. Dean and Stark, Ind. Bng. Chem.

12,

386 (1920).

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