THE CONDENSATION OF SECONDARY
HEXYL ALCOHOLS WlTH PHENOL
N THE PRESENCE OF ALUMiNUM

CHLOREDE

Thesis for {ha Degraa of M. 3.
MICHIGAN STATE COLLEGE

Ralph James Curtis
194!

THE CONDB‘JSATION OF SECONDARY HEXYL ALCOHOLS WITH PHENOL

IN THE PRESE'I'CE 0F ALUiéINUJ CHLORIDE

by
Ralph Jemee Curtis

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

$1st OF SCIENCE

Department of Chemistry
1941

ACKNOWLEDGMENT

To Dr. R. C. Huston, the writer wishes to
express his sincere appreciation fbr the aid and
guidance which have made possible the investigation

of this problem.

33162-1.

Introduction - ------ - - - - - -

TABLE OF CON'I‘ENI‘S

Historical - - - - .............

Theoretical

Experimental

1 Preparation of Alcohols

II Condensation with Phenol -

III Preparation of Derivatives

IV Proof of Structure - - - -

Discussion

laterials -
Tables - - -
Summary - -
Bibliography

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------ 2
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- - - - - - 1‘
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------ 24

15, 25. 25
------ 27
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Introduction

The work on condensation reactions, using aluminum chloride as
a catalyst. was started in this laboratory in 1916 when Huston and
Friedemann (3) reported the condensation of bensyl alcohol with
benzene. Since that time Huston and oo-sorkers have studied the
condensation of saturated aliphatic alcohols and several mixed
aliphatic-aromatic alcohols with bensene and bensene nuclei in
the presence of this same catalyst.

In 1936 Huston and Hsieh (11) reported the condensation of
some simple tertiary alcohols sith phenol. This was followed
closely by the work of Huston and Hedrick (16) in 1937. and of
Huston and Guile (20) in 1938, who investigated the tertiary
heptyl and tertiary octyl alcohols respectively.

The secondary amyl alcohols were condensed with phenol by
Huston and Esterdahl (24) in 1940.

To further investigate the scope of this reaction the secondary
henyl alcohols have been condensed with phenol in the presence of
aluminum chloride.

Historical

A review of the literature reveals that many papers have been
written concerning the alkylation of phenols. There are three general
methods for the preparation of alkyl phenols. all of them involving
the use of a catalyst. First. the direct alkylation of phenols using
albyl halides. alcohols. acyl chlorides. and alkenes in the presence
of a variety of catalysts. Second. the replacement of a variety of
groups by hydronyl in alhyl bensene derivatives. And last the re-
arrangement of alkyl phenyl eihers to yield albyl phenols.

A great variety of catalysts have been used in these reactions:
namely. concentrated sulfuric acid, acetic acid, perchloric acid,
phosphoric acid. and magnesium and aluminum chlorides.

‘This paper deals with the albylation of phenol. using alcohols
and anhydrous aluminum chloride. so only those papers dealing with the
same reagents will be included in this review. It must be mentioned,
however. that in 1884 Auer (1), using a.mdaiure of zinc and sine
chloride as a catalyst, condensed simple aliphatic alcohols with
phtnol and obtained yields of alkyl phenols. Several years later.
in 1897, Net (2) condensed bensyl alcohol with bensene in the presence
of aluminum chloride and reported a small yield of diphenyl methane.
This work was repeated in 1916 by Huston and Friedman: (3) and a
thirty per-cent yield of diphenyl methane was reported. This work
was followed by that of Huston (4) in which benzyl alcohol was con-
densed with phenol, anisole. and phenetole in a similar manner as
with bensene. He reported yields of forty five to fifty per-cent of

the alkylated products.

This successful work led to further investigation concerning the
possibilities of this reaction. Negative results were obtained by
Huston and Sager (5) in 1926 when attempts were made to condense
phenyl propyl and phenyl ethyl alcohols with benzene. These same
workers reported that methyl, ethyl, prepyl, iso-propyl. n-hutyl.
ieo-butyl and iso-amyl alcohols did not condense with bensene under
similar conditions. They fbund, however. that allyl alcohol did con-
dense with benzene to give a sixteen per-cent yield of allyl benzene.
Allyl alcohol was condensed with phenol by Huston and Newmann (6) in
1933. From this it was concluded that aluminum chloride favored con-
densation only when the alpha carbon of the alcohol was double bonded
or the member of a benzene rim.

To substantiate this conclusion Huston and co-workere (7) con-
densed diphenyl carbinol. methylphenyl carbinol, and ethylpheqyl
carbinol with phenol and obtained good yields of condensation products.
Diphenyl carbinol, in which both carbon atoms adjacent to the carbinol
group are members of a benzene ring, gave a.much larger yield of
albylated product than benryl alcohol under the same conditions. This.
they pointed out. was definite evidence that aromatic unsaturation has
a great effect on the activity of the bydrenyl group.

In 1933 it was reported by Huston and Davis (8) that triphewl
carbinol did not condense with bensene. The product isolated was
triphenyl methane and not the expected tetraphenyl methane.

The condensation of bensyl alcohol with o-cresol, p-cresol, and
m-cresol in the presence of aluminum chloride was reported from this
laboratory by Huston and co-workers (9). In each case, two mono-

substituted and one disubstituted derivative was obtained.

To investigate the effect of strain in cycloalhyl carbincls.

Huston and Goodemoot (40) condensed cyclohexyl. cyclopentyl, and
cyclobutyl carbinols with benzene. They found that the carbincls
showed a progressive decrease in activity as the number of carbons
in the ring was increased from four to six.

Investigation of several diaryl-alkyl and dialhyl-aryl carbinols
by Huston and co-workers (10) showed that they did not condense with
benzene, but were dehydrated. yielding the corresponding unsaturated
products.

In 1936 Huston and Hsieh (ll) investigated some saturated aliphatic
alcohols and reported that primary alcohols did not condense with
benzene or phenol. secondary alcohols did condense with benzene and
phenol giving small yields. and tertiary alcohols condensed with phenol
under the influence of aluminum chloride. These workers also condensed
some tertiary alcohols with toluene. m-cresylmsthyl ether and anisole.

Previous to this work. Sowa Houston and Nieuwlsnd (12) reported
the condensation of several primary alcohols with phenol. However.
they used boron trifluoride as the catalyst. The same year it was
reported by Tsukervanik and Nazarova (13) that tertiary alcohols
condensed with phenol is the presence of excess aluminun.chloride
to give good yields of alkyl phenols. Under the same conditions
secondary alcohols condensed to give insignificant yields of the
desired products.

In 1934 Huston and Fox (14) condensed tertiary butyl. tertiary

amyl, and the three possible tertiary hexyl alcohols with benzene.

Further investigation in this field led to the condensation of
the higher tertiary alcohols with benzene and phenol; namely the
heptyls and octyls. Huston and Binder (ls) condensed the tertiary
heptyl alcohols with benzene. and Huston and Hedrich (16) condensed
the same alcohols with phenol. Several workers have studied the
condensation of the tertiary octyl alcohols with benzene. Huston
and Anderson (18) condensed methyl ethyl n-butyl and methyl ethyl
tertiary butyl carbinols with benzene and phenol. Huston and Sculati
(1?) studied the condensation of some dimethyl anyl oarbinols with
benzene. Huston and Cline (39) and Huston and Breining (19) worked
with the methyl diprcpyl and propyl diethyl oarbinole respectively.
The condensation of sons dimethyl anyl carbinols with benzene was
reported by Huston and unseen (21) in 1940. The dinethyl smyl car-
binols were condensed with phenol by Huston and Guile (20) in 1939.
and it was reported that fragmentation of the carbon chain occurs
when the snyl radical is highly branched. Sons alkyl phenols of
lower molecular weight were formed as a result of this fragmentation.

In 1940 Huston and Jackson (22) reported the condensation of some
diphsnyl alkyl carbinols with phenol. and Huston and Hughes (23) con-
tinued the investigation of dialhyl aryl carbinols in regard to their
condensation with phenol.

The same year Huston and Ebterdshl (24) condensed the secondary
amyl alcohols with phenol and reported that a mixture of’prcducts
was formed as a result of dehydration of the alcohol followed by con-

densation.

At the present time the condensation of the methyl dipropyl car-
binols with phenol, and the condensation of several secondany alcohols
with benzene are being studied in this laboratory by Heloy and Kaye.

This work is a continuation of the study of secondary alcohols.

It specifically deals with the condensation of the secondary henyl
alcohols with phenol under the catalytic influence of anhydrous

aluminum chloride.

Theoretical

The work of Huston and co-worksrs has shown that unsaturaticn of
the alpha carbon atom, whether it was double bonded or the member of
a benzene ring, favored condensation of alcohols with benzene or ben-
zene nuclei in the presence of aluminum chloride. This strained con-
dition results in an unstable bond between the oxygen and carbon atoms,
greatly increasing the activity of the hydroxyl group.

This type of bond is present in bensyl (a) and allyl (b) alcohol,
both of which condense easily with phenol and benzene. The electron
pair between the OH group and O atom is attracted strongly by both
groups. resulting in the type of bond found in a.nolscu1e cf'chlorine.
$1.01: This bond is known to be unstable and very active. Extending
this examination to the saturated primary (c). secondary (d). and
tertiary (e) aliphatic alcohols. a different electronic arrangement
is fcund. The attraction of the carbon atom for the electron pair
between C and 0 decreases progressively as we go frcn primary to
secondary to the tertiary alcohols. This may be shown experimentally
by the ease of replacement of hydrosyl by halogen of a halogen acid.
and the ease of dehydration of tertiary alcohols. This same condi-
tion exists to a lesser extent in secondary alcohols, however. the
type of bond present in both cases is similar to that found in a
molecule of ivdrogen chloride, H :C'E'lt. These conditions may be rep-

resented electronically by the following formulas.

5 .. H.- 3. 5 .. H
c635=g39‘fi H.9§c:g:g=n mg: §:H
(a) (b) (6)
B. .. R
soc :o:n 3:6 :04!
n .. fl .
(d) (e)

— n._-_-g:.=—=_.~v_

In view of this tertiary alcohols should condense readily with
bensene and phenol, secondary alcohols less easily and primary alco-
hols only under special conditions. Experimental evidence bears
this out.

Although extensive work has been done in the field of condensa-
tion reactions, and several mechanisms preposed to explain the path
of the reactions. no one mechanism has been conclusively established.
The situation is further complicated due to the variety of catalysts
and conditions employed by different workers. In discussing three
of the proposed mechanisms. a tertiary alcohol will be used for con-
venience. pointing out each time the application of the mechanism to
a secondary alcohol.

The mechanism proposed by Tentervanik and Nasarova (13) may be
presented by the following equations. using as an example tertiary
butyl alcohol.

(a) (083)3ooa+uc13 -+ A1c1200(caa)3 + HCl

(8) Alcizoc(ca3)3 -> Gag-gang + LlCleH

3

(D) (033)30-01 + 0686 -+- (crxa)3o—osns+ H01

This theory proposes as intermediates an alkene (B). and an
alhyl.chlcride (0) formed by the addition of HCl to the alkene.
The chloride them condenses with the hydrocarbon (D) (Friedal-
Craft reaction) in the presence of excess aluminum chloride to
form the alkyl benzene. Applying this mechanism to a secondary
alcohol. such as methyl sec-butyl carbinol, the reaction could

proceed by the formation of the following intermediates.

H CH3
6113-ij -CHz-CH3 4' A1013 -)- CH3-C= b-CHz-Clig + H01 4' £10120}!
CH3-C: é-CHz-Cfig + H31 ->’ CH3-E EECHg-CH3

The HCl formed in the first equation would add to the dehydration
product of the alcohol according to the rule of Harkownikoff, and a
tertiary alkyl chloride would result. This tertiary hexyl chloride
would then condense with phenol or benzene to yield a.tertiary alkyl
derivative.

In criticism of this theory it seems unlikely that an aluminate
would be formed as in equation (A). due to the fact that it is diffi-
cult to replace the hydroxyl hydrogen of a tertiary alcohol. However.
the hydrosyl hydrogen of a secondary alcohol is more labile and could
be replaced with less difficulty. Furthermore. it this mechanism is
correct. 861 should not be liberated during the first three steps of
the reaction. Hedrick (16). investigating this theory. found that
heat and HCl were instantly evolved, and when phenol was added to the
mixture no evidence of reaction was noted. A small.yield of alkyl
phenol was reported.

A similar mechanism is advanced by McKenna and Sowa (25). except
that an alkene is the only intermediate formed during the condensa-
tion. They have shown that when benzene is alkylatsd with alcohols
using boron trifluoride as a catalyst. the alcohol is first dehydra-

ted and then the alkene condenses with the hydrocarbon.

wa-cm-caz-caz-on + BF3 --> cna-cnz-b=csz + 320

cn3-cH3-gzcaz + cgné 5—33 083-4332 ’ - c535
gs
3

10

As evidence for this mechanism they state that normal and secondary
alcohols give identical products as do the iso and tertiary isomers.

A like mechanism is suggested by accreal and Niederal (26) using
zinc chloride as the catalyst. This mechanism was extended to alco-
hols such as diphenyl carbinol by welsh and Drake (27). They suggest
that alcohols of this type may split out water from the OH of the
carbincl group and a nuclear hydrogen.of the benzene ring.

There is little evidence against this mechanism since it has been
shown by many workers (28) that alkenes do condense with aromatic
hydrocarbons in the presence of aluminum chloride.

In contrast to the work of MbKenna and Sosa. Huston and Sager (5)
reported that primary alcohols did not condense with benzene in the
presence of aluminum chloride under ordinary conditions. However,
chsnna and Sosa used ZnClg as a catalyst and carried out the reaction
at a higher temperature than employed in the Huston method.

There is some evidence to show that alhyl phenyl ethers rearrange
in the presence of‘a catalyst to form allyl.phenols. Smith (29) re-
ported the rearrangement of several alhyl phenyl ethers when treated
in the cold with equal molecular portions of aluminum chloride. The
ethers were prepared from alkyl halides and the alkali salt of the
phenOI.

cgnsom. + 3-01 ->- 063501! + N‘aCl
cgnsqli t 1101; -s- ROgHgOH
Similar rearrangements hays been reported by numerous workers

(30), and it may be concluded that if ethers are formed during the

reaction they may rearrange to alhyl phenols.

11

When allyl bromide and sodium phenolate are brought together in
an alcohol medium a 90; yield of allyl ether is obtained, but in a
benzene medium there is only a 3075 yield of the ether and a 70% yield
of o-allyl phenol. Thus Claisen (31) points out that an ether is not
a necessary intermediate, for phenyl alkyl others do not rearrange to
the phenols under the condition of formation.

This other formation theory is also refuted in part by the work
of Huston and oo-workers (4) (ll). Good yields of condensation
products have been reported from reactions in which there is no
possibility of ether formation.

new addition products of aluminum chloride have been reported
(32). and with this in mind Huston and Evert (33) began an investi-
gation of similar complexes involving alcohols and phenol. Briefly
this theory is; A complex molecule is formed between the outer
shell of electrons of aluminum chloride and the reacting substances.
The resulting poly-molecule is not stable at the reaction tempera- -
ture. and the atoms rearrange to form stable compounds. This theory.
although promising. does not explain new of the results obtained

in this laboratory.

Experimental

I Preparation of Alcohols

Four of the alcohols condensed were prepared by the following
method (38).

(l) 3-methyl pentanol-Z

In a dry three liter triple necked flask equipped with reflux
condenser. mercury sealed stirrer, and dropping funnel was placed
2.4 moles of dry magnesium turnings and 100 ml. of anhydrous ether.
The reaction was protected from carbon dioxide and moisture in the
air by soda-lime tubes on the condenser and dropping funnel. Two
moles of secondary butyl bromide dissolved in 120 ml. of anhydrous
ether was then added drapwise over a period of three hours.

After the reaction started the flask was cooled in a water bath
to prevent loss of ether by vigorous refluxing.

The Grignard reagent thus prepared was allowed to stand overnight,
cooled to ~5°C. in an ice-salt mixture and then 1.8 moles of freshly
distilled acetaldehyde (34) in 120 al. of anhydrous ether was added
as rapidly as possible keeping the temperature below 10°C..

After standing a short time the reaction mixture was filtered from
unused magnesium and decomposed by pouring on 600 gms. of ice. The
precipitated magnesium.compounds were dissclyed with dilute hydrochloric
acid while the temperature was kept at 0°C. by the addition of ice.
The resulting two layers were separated and the aqueous layer extracted
with three portions of ether. The combined other solutions were washed

with dilute sodium carbonate solution, then with water and finally

dried over anhydrous potassium carbonate for several hours. The
ether was removed and the residue fractionated, using a modified
Claisn flask.

Boiling range of fraction used, 134-13700.

Yield was 46% of the theoretical.

(2) 3.3-dimethzl butanol-2
This alcohol was prepared by the method described above except

that tertiary butyl bromide was used.
Boiling range of fraction used, 119-121°C.

Yield was 27;”! of the theoretical.

(3) gexancl-g
The same general procedure was followed except that the ethyl

Grignard reagent was prepared from ethyl bromide. followed by the
addition of normal butyraldetyde.
Boiling range of fraction used. 133-13690.

Yield was 54.5% of the theoretical.

(4) 4-mthzl pentaggl-g
Prepared from the ethyl Grignard reagent and iso—butyraldehyde.

Boiling range of fraction used, 125-138°c.

Yield was 63% of the theoretical.

Kennel-2 and 4-methyl pentgol-z were obtained from the stock

room and twice redistilled before using.

14

Alcohols condensed were:

(1) 3-methyl pentanol-z

(2) 3.3-dimethyl butanol-2

(3) hexanol-S

(t) 4-methyl pentanol-3

(5) hexanol-z

(6) 4-methyl pentanol~2

V
II Condensations with Phenol

The six secondary hexyl alcohols were condensed with phenol by the
two general methods used by numerous workers in this laboratory.

(1) The first method employed by the writer was similar to the
one used by Huston and Guile (20) except that the reaction.flask was
cooled only when the temperature exceeded 50°C. This method proved
unsatisfactory due to the formation of a resinous complex between the
phenol, alcohol and aluminum chloride that greatxy hindered stirring
of the mixture.

After preliminary investigation to detennine the relative amounts
of reactants necessary for s maximumryield, the following procedure
was adapted and will be described in detail.

(2) A.quarter mole (25.5 gas.) of the alcohol and a.halr mole
(47 gas.) of molten phenol were weighed into e.dry 500 ml. three
necked round bottom flask. The flask was then fitted with a.gxycerine
sealed stirrer and a reflux condenser with drying tube to protect the
reaction from moisture in the air. To this mixture was then added

.18 mole (24 gme.) of anhydrous aluminum chloride from a shaker

15

bottle designed to protect the reagent from moisture during the
transfer. The flask was cooled in a water bath if the temperature
exceeded 35°C. during the two hour addition period.

The color of the reaction mixture changed from a light yellow
to a brilliant red as the aluminum chloride was added and some
hydrogen chloride was given off. The viscosity of the solution also
increased. especially in the condensations where solid products were
obtained. The reaction was stirred for four hours after the aluminum
chloride was added and it was during this period that large volumes
of H01 were evolved. The flask was warned in a water bath (SO-60°C.)
it the solution became viscous enough to hinder stirring.

After standing overnight the semi-solid glass like reaction mix-
ture was hydrolyzed by pouring on a 1:1 mixture of ice and hydrochloric
acid. The resulting two layers were separated and the aqueous layer
extracted with three portions of ether. The combined ether and organic
layers were washed several times with dilute sodium carbonate solution
to remove acid and then dried over anhydrous sodium sulfate for several
hours. The ether was removed on the steam bath and the residue
fractionated at reduced pressure using a Claisen flask.

The first distillation.yielded three main fractions. A small
amount below 85° at 15 mm. pressure which consisted mainly of‘un-
condensed alcohol and traces of its chlorides; a second fraction
between 85° and 115° at 4 ms. pressure consisting chiefky of phenol;

- and a third fraction between 115° and 130° at 4 mm. pressure that was
the desired product. A small amount. 2 to 4 grams. of tarry residue

remained in the flask at the end of the distillation.

The llS°-130°C. fraction was refractionated several times at 4 mm.
pressure until a colorless alhyl phenol was obtained. The products-
that crystallised were separated from oily impurities by porous plate
treatment, and when possible they were recrystallized from petroleum
ether or a 50% mixture of alcohol and petroleum ether.

Table I shows the yields of alkyl phenols obtained by the two
methods described above. It will be noted that the yields from the
two methods are in the same approximate ratio. but much higher when
the solvent is omitted.

Table II records the physical constants and analyses of the prime

cipal products isolated.

Table I
W W thou 01 6
Alcohol Number of iv. yield of Number of iv. yield of

         

Wt“. i .1 PM“ W. M°°
4-methyl 2 23.11 a 54.01
pentanol-3

3-methyl 3 26.47: a 59.1%
pentanol-2
3.3-dimethyl 3 24.5}: 3 54.3%
butancl-z

t-methyl 3 17.1% 4 41.0%
pentanol-B

hexanol-z 4 8.5% 4 22.5%
hexanol-s 2 10.2% 2 25.5%

17

III Preparation of Derivatives

The bensoyl ester (35) and alpha-naphthylurethane (36) derivatives
were prepared for all the alkyl phenols obtained by the method previous-
ly described. '

(l) Bengal efierg

Three grams of the phenol were dissolved in 4 ml. of pyridine in a
50 ml. Erlenmeyer flask and 3 ml. of. bensoyl chloride was added. After
the initial reaction had subsided the mixture was refluxed over a low
flame for 1.5 hours. cooled, and then poured on ice. The oily product
was then extracted with two portions of ether. The ether solution was
washed with cold dilute sulfuric acid to remove pyridine, and then
with dilute sodium carbonate solution to remove excess acid. After
removal of the other on the steam bath the ester was distilled at re-
duced pressure using a modified Claisen flask. The crystalline esters
were recrystallised to constant melting point from 85% alcohol solution.
If the ester failed to crystallize on cooling and standing, it was re-
distilled and the boiling point carefully determined. See Table IV for
data on these derivatives.

(2) Alpha-naphthylurethane!

One gram of the alkyl phenol was placed in a clean dry test tube and
an equal volume of alpha-naphthyl isocyanate added. The reaction was
catalysed with two drops of an anhydrous other solution of trimethyl
amine, the test tube fitted with a Ca612 tube and then heated on the
steam bath until the contents of the tube solidified on cooling. ‘flbe
derivative was extracted with boiling ligroin, and the solution filter-

ed while hot to remove insoluble material. The alpha-naphthylurethane

crystallised out when the filtrate was cooled in an ice bath. It was
removed and recrystallised to a constant melting point from hot ligroin.
The data on these derivatives are given in Table III.

IV Proof of Structure

hiring the course of this work it was observed that the melting
points of the alkyl phenols prepared from 4-methyl pentanol-3,
3-methyl pentanol-Z and 3,3-dinmthyl butanol-Z, agreed closely with
the melting points of the tertiary hexyl phenols prepared and identi-
fied by Hsieh (ll). This suggested the possibility that the secondary
hexyl alcohols. with branching on the carbon atom adjacent to the car-
binol group. may have been dehydrated during the condensation reaction
resulting in the formation of tertiary products. Following this lead.
small samples of 2-methyl-2-p-hydroxyphenyl pentane and 2,3-dimethyl-
2-p-hydroxyphsnyl butane synthesised by Hsieh were obtained, and their
alpha-naphthylurethane derivatives prepared.

The alhyl phenol obtained from the condensation of 3.3-dimethyl
butanol-2 with phenol. was proven to be the tertiary 2.3-dimethyl 2-p-

hydrosyphenyl butane.

 

 

Melting point Helting point
Alkyl phenol of alkyl phenol of urethane
2,3-dimethyl
2-p-hydrosyphenyl butane 105-106 115-416
from
3.3-dimethyl butanol-2 lOt-lOS 115-116
and phenol

Mixed melting points of the alpha-naphthylurethanes and of the alkyl
phenols showed no depressions. proving that the compounds are identical.

The rearrangement of 3.3-dimethyl butanol-Z will be discussed in an-
other section of this. thesis. (See discussion)

19

The alhyl phenol obtained from the condensation of 4-methyl
pentancl-3 with phenol, was proven to be the tertiary 2-methyl-

2-p-hydrcxyphenyl pentane.

 

 

 

Melting point Melting point
Alhyl phenol of alkyl phenol of urethane
2-methyl
2-p-hydroxyphenyl pentane 37-38 125.5-126.5
from
4-methyl pentanol-B 32-33 124.5-125.5
and phenol

A mixed melting point of the alpha-naphthylurethanes showed no de-
pression. proving that the compounds are identical. Due to the low
melting point and oily nature of the phenols a mixed melting point
determination was not made. The latter product was purified by dry-
ing on a porous plate and was not recrystallised due to its extreme
solubility in all solvents used. However, this does not greatly
effect the melting point of the alpha-naphthylurethane as shown in
the above table.

The structure of the alkyl phenol resulting from the condensation
of 3-methy1 pentanol-z with phenol was proven in a similar manner.
3-methyl-3-p-hydroxyphenyl pentane was prepared from 3-methyl
pentanol-S and phenol by the method of Huston and Hsieh (ll). The
fraction distilling at 123-127°C. at 4 mm. pressure was retraction-
ated several times. and then separated from oihy impurities by drying
overnight on a porous plate. Mixed melting points of the alpha-
naphthylurethanes and alkyl phenols showed no depressions. proving
that the compounds are identical. The reported melting point of

3-methyl-3-p-hydrcxyphewl pentane is 59-60°C.. however, this is the

20

melting point of the recrystallised product. When the tertiary phenol
is purified by the same treatment given the product from the secondary

alcohol the melting points are identical.

 

 

 

Melting point Melting point
Alkyl phenol of alkyl phenol of urethane
3-methyl
3-p-hydroxyphenyl pentane 54-55 l47-148
from
3-methyl pentanol-2 54-55 lt?.5¢148.5

The structures of the alkyl phenols resulting from the condensa-
tion of hexanol-z, hexanol-3 and 4-methyl pentancl-2 with phenol were
not proven, due to the fact that their alpha-naphthylurethane deriva-
tives could not be recrystallised to a sharp melting point. This
indicates that the products isolated were mixtures of isomers resulting
from the condensation of phenol with the dehydration product of the
alcohol.

As previously stated, the fractions distilling at lie-130%. at .

4 mm. pressure were redistilled several times to obtain the pure alhyl
phenols. During this procedure, repeated attempts were made to isolate
more than one product from the reaction. but due to the highly viscous
character and the closeness of the boiling points of the phenols. this
could not be done. Several techniques were used in these distillations.
but in every case distinct fractions of different products could not be
separated.

Two products are possible from each alcohol if an alkene is an
intermediate in the reaction. Hexanol-2 could be dehydrated to form

hexane-2, while hexanol-B could form.the alkenes hexane-2 and hexene-a.

21

Inasmuch as the condensation products of these alkenee could not be
separated it was not determined which phenol was present in the
largest quantity. The alpha-naphthylurethane derivatives of the
same alkyl phenols. synthesised from the alkyl bensenes by Kaye.
exhibited the same behavior and no definite conclusions could be
drawn.

It may be pointed out, however, that the alkyl phenol from
4-methyl pentanol-2 appeared to be primarily 4-methyl-3-p-hydroxy
phenyl pentane. This was not definitely provsn. but is evident from
a study of the derivatives of this product and of the alkyl phenols

made from the alkyl bensenes of 4-methyl pentanol-3 and 4-methyl

 

 

pentanol-z.

melting point
Alhyl phenol of urethane

t-methyl pentanol-2

plus bensene -e- alkyl phenol 108-112
from

e-methyl pentanol-2

and phenol 120.5-123.5

4-methyl pentanol-3
plus benzene -—e- alkyl phenol 116-124

The alkyl bens ones from 4~msthyl pentanol-2 and 4-methyl pentanol-3
were converted to the alkyl phenols by Kaye. using the method of
Huston and Guile (20).

The para position is assigned to the substituted hexyl group in
these phenols as a result of extensive work done in this laboratory

with a variety of alcohols (ll) (24).

22

Discussion

The results reported herein indicate that in the presence of
anhydrous aluminum chloride. the secondary hexyl alcohols are easily
dehydrated and condense with phenol to form products other than the
ones expected. The alcohols with branching on the carbon atom adja-
cent tc the carbinol group give the largest yields of alkyl phenols.
showing that they are dehydrated more'easily than the straight chain
isomers. is would be expected. tertiary hexyl phenols were formed
in every case where this structural arrangement was present. In con-
trast to this. no prediction could be made in regard to the alkyl
phenols formed from the condensation of the dehydration products of
the straight chain alcohols with phenol. Experimental evidence bears
this out as shown in the preceding section of this thesis.

A detailed analysis of the molecular rearrangement noted in

3.3-dimethyl.butanol-2 is beyond the scape of this thesis. Briefly.
the rearrangement is similar to the pinasolone transformation in
which an alhyl radical migrates during a process of dehydration.
The dehydrating effect of the aluminum chloride brings about the
interchange of two radicals on adjacent carbon atoms. namely CH3
and 01-]. followed by the elimination of a molecule of water. The
resulting symmetrical olefin then condenses to form the tertiary
phenol.

The mechanism of aluminum chloride condensation reactions as
proposed by Tsuhervanih and Nhsarcva (13) suggests that an inter-
mediate alkyl chloride is formed during the early stages of the

reaction. The theory is not so plausible when applied to tertiary

23

alcohols. but gains credence when secondary alcohols are being con-
sidered. During the course of several condensations it was observed
that only insignificant amounts of HCl were liberated during the addi-
tion period of the reaction. However. after addition of aluminum
chloride was complete large volumes of H01 were given off. indicating
that the HCl formed during the initial stages of the reaction may

have added to the alkene forming an alkyl chloride. With this in
mind several low fractions from the condensations were refraction-
ated in attempts to isolate traces of the alkyl halides. but negative

results were obtained in every case.

Materials

Secondary butyl and tertiary bromides were prepared from the
corresponding alcohols by the action of sulihric and hydrobromio
acids (37).‘

Acetaldehyde was prepared from paraldehyde (B.P. 21-26°C.)

Normal butyraldehyde - Eastman's (Practical). Redistilled
before using. (B.P. 73-76°C.)

Iso-butyraldehyde - Eastm's (0.9. grade) 3.13. 61-62%.

Ethyl bromide (C.P. grade) B.P. 38-4006.

Hexanol-z - Eastman‘s (Technical) B.P. 137-140°C. Redietilled
before using.

d-methyl pentanol-Z - Eastman's (Technical) B.P. 129~1az°c.
Redistilled before using.

Phenol - Mallinkrodt's crystals. Redistilled before using.

Benseyl chloride - Eastman's (C.§. grade)

Alpha-naphthyl ieocyanate - Eastman's (C.P. grade)

Magnesium turnings especially prepared for Grignard reactions.
were dried in an oven at 40°C. before using.

Anhydrous ether - (C.P. grade) Dried over metallic sodium.

Ligroin -- (B.P. 60~90°C.) Dried over metallic sodium.

Petroleum ether - (B.P. 30-6500.) Dried over metallic sodium.

Benzene used in molecular weight determinations was thiophene
free. 6. P. grade.

Aluminum chloride - Baker's anhydrous.

o
Sumethyl pentanol-3 - Prepared by Hsieh (ll) B.P. 120-123 C.

2.2.2 a 222. «3.828 and... $12 a m “no.8 s. u omamfio n8 .28.

 

 

 

 

 

 

 

 

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Table III

Alpha-naphthylurethanes

 

 

26

 

Alpha-naphthylurethanes of M.P.°C Analysie* flN
2%“W1'2‘p- 124e5-125e5 4e05
hydrcxyphenyl pentane
3-methyl-3-p- 147.5-148.5 4.00
hydroxypheny l p mtane
2 ’ 3‘dimfithy 1-2.9- 115-116 4. 10
hydroxyphenyl butane
4-methyl-3-p- 120.5-123.5 4.14
hydroxyphenyl pentane
4-methyl-2gp-
hydroxyphenyl pentane
2-p-hydroxyphenyl hexane 95-97 4.12
Bap-hydroxyphenyl hexane
3-p-hydroxyphenyl hexane 93-95 4.06
2-p-hydroxyphsnyl hexane (77-80)

*Calc. for czanzsozu N . 4.03%?

Table IV

Bensoyl Esters

 

Benzoyl Ester of

M.P. er B.P.°C.

Analysis Foundit

 

 

 

 

 

o .19... .21..
amethyl-z-p- 185-187 Ce 80e‘7 ?e61
hydrexyphenyl pentane B.P. 4mm.
3-mothyl-3-p- 75-75 °c. 80.54 7.51
hydroxyphenyl pentane fl.P. .
2.3-dimothy1-2-p- 53.5-54.5°c. 80.75 7.77
hydroxyphenyl butane M.P._
4-mothy1-3-p- lea-193°C. so.se 8.10
hydroxyphenyl pentane B.P. 4mm.
4-methyl-2-p-
hydroxyphenyl pentane
2-p-hydroxyphenyl hexane 189-194°C. 81.10 7.91
3-p-hydroxyphenyl hexane B.Pu 4mm. '
3-p-hydroxyphonyl hexane 190-195°C. 81.04 7.75
2-p-hydroxyphenyl hexane 8.?» 4mm.

mgnzzoz m a . W

 

27

Salmary

l. The six possible secondary henyl alcohols have been condensed
with phenol in the presence of aluminum chloride.

2. gamethyl pentanol-Z. 4-methyl pentanol-B and 3.3-dimethyl
butanoIIQ condensed with phenol to form the tertiary hexyl phenols
3-methyl-3-p-hydroxyphenyl pentane. 2-methyl-2-p-hydroxyphenyl
pentane and 2.3-dimethyl-27p-hydroxyphenyl butane. respectively.

3. Hexanol-z. hexanol~3 and 4omsthyljpentan01-2 condensed with
phenol to form mixtures of isomers that could not be separated.

4. g (The benscyl ester and alpha-naphthylurethane derivatives have
been prepared.

5. Hexanol~3. somethyljpentanol-z. 4-methyl2pentanol-3 and

3. 3-dimethlebutanol-2 were prepared.

l.

3.
4.
5.
6.
7.
8.
9.

10.

21.

22.

Auer

Net

Huston and Friedemann
Huston

Huston and Sager
Huston and Neenenn
Huston. Lewis. Grot emt
Huston and Davis

Huston and others

Huston end Wilsey
Huston end Hredel
Huston and HecComber

Huston end Hsieh

Sowe.Hsnnton and Nieuwlend

Tsukervanik and Neserove

Huston and Fox
Huston and Binder
Huston and Hedrick
Huston and Sculati
Huston and Anderson
Huston end Brsining
Huston and Guile
Huston end thson

Huston and Jackson

Bibliography
Ber.
Ann.
J. Am. Chem. Soc.
J. Am. Chem. Soc.
J. Am. Chas. 800.

Master ' s Thesis

1...
.4

to
ID
0)

I319. 19 |

Michigan State

J. Am. Chan. Soc.

Haster's Thesis

22

Hichigan State

J. Am. Chem. Soc.
Ibid
Ibid

Haster's Thesis

g;

l3! ES

Hichigan State

Mhster's Thesis

Michigan State

Master's Thesis

Michigan State

J. Me “I'Me 806.
J. Au. Chem. Soc.
@031. Abl’t.

Master‘s Thesis

E:

i.

Michigan State

Master's Thesis

Michigan State

J. Am. Chem. Soc.

Elaster ' s Thesis

32

Michigan State

Master's Thesis

Michigan State

Master's Thesis

Michigan State

J. Am. Chem. Soc.

Master's Thesis

9;

Michigan State

J. Am. Chem. Soc.

9;

669
255
2527
2775
1955

College
1365

College
2379
4484
1506

College
College

College
439

709

443

College

College
2001

College

College

College
69

College
541

(1884)
(1897)
(1916)
(1924)
(1926)
(1933)
(1927)
(1933)
(1931)
(1930)
(1932)
(1933)
(1934)
(1935)
(1936)
(1935)
(1936)
(1934)
(1935)
(1937)
(1936)
(1936)
(1938)
(1939)
(1940)

(1941)

23.
24.
25.
26.
27.
28.

29.

30.

31.
32.

33.

35.

36.
37.
38.
39.

40.

Huston and Hughes

Huston and Esterdahl

Doctor's Thesis

Michigan State College
haster's Thesis

Michigan State College

thenna and Sosa J. Am. Chem. Soc. 39; 470
MoCreal and Nisderal J. Am. Chem. Soc. f 37 2625
welsh and Drake J. Am. Chem. Soc. Q9 59
Berry and Reid J. Am. Chem. Soc. 32 3142
Cline and Reid J. Am. Chem. Soc. 3; 3150
J. Am. Chem. Soc. 32 3157
Smith . J. Am. Chem. 300. .§§ 415
Nisdersl and Natelson J. Am. Chem. Soc. 13. 1928
Sosa and Niesland J. Am. Chem. 500. (g; 2019
Claisen z anger. chem. ‘§§ 478
Claisen Ber. ‘§§ 275
Claisen Ann. ggg 69-120
Barty end Adams J. Am. Chem. 500. .§1 371
Claisen Z anger. chem. _3_§_ 478
Gangloff and Henderson J. Am. Chem. Soc. 32 1420
Adkins J. Am. Chem. Soc. 33‘ 2175

Huston and Evert
Organic Synthesis

Shriner and Fuson

French and Wertel
Organic Synthesis
Organic Synthesis

Huston and Cline

Huston and Goodemoot

haster's Thesis
Michigan State College
vow. XII p.46

The Systematic Identification of
Organic Compounds. pg.

J. Am. Chem. Soc. 353, 1736

Coll. Vol. I p. 23
Volume III p. 46
Blaster's Thesis

Hichigan State College
J. Am. Chem. Soc. _5§ 2432

(1940)
(1940)
(1936)
(1935)
(1938)
(1927)
(1927)
(1927)
(1933)
(1931)
(1932)
(1923)
(1925)
(1919)
(1935)
(1923)
(1917)
(1922)
(1938)

142

(1926)

(1939)
(1934)

29

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