m-Diarylbenzenes: Syntheses and ultraviolet spectra

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m-DIAEYLBENZENES:

SYNTHESES AND U LT RA VI OL ET SPECTRA

By F re d Thornton Reed

Thesis

submitted to the F a c u l t y of the Graduate School of the Un iv e r s i t y of Maryl an d in partial fulfillment of the requirements for the degree of Doctor of Philosophy 1950

UMI Number: DP70538

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A-CKNOWLEDGEM ENT

The author wishes to express his deep appreciation and sincere gratitude to Dr.

G. F or rest Woods for his

m a n y suggestions and his u n t i r i n g guidance and assistance throughout the entire course of this investigation. out his counsel and direction,

With­

this thesis would not have

been possible.

±57899

TABLE OF CONTENTS I NTRO DU CT I ON H ISTORICAL

.................................................

1

...................................................

3

m -Ter ph en yl derivatives 0-Terphenyl d er ivatives DISCUSSION

• ..............................

..............

Synthesis

EXPERI MEN T AL

spectra

64

.................

65 65

.............................

3 -Carboxybi phenyl

4-Xenyl bromide

64

..................

Monoethyl ether of dihydroresorcinol

2-Xenyl iodide

40

......................................

Silver Salt of di hy dr or es or c in ol

3-Xenyl bromide

15

...............................

...................................................

Di hy dr or es or ci no l

8

15

.............. ... . ............................

U lt raviolet

3

.......................................

69

..........................................

69

.........................................

70

3 -P he ny l -z^^-Cyclohexenone

............................

70

3-( 4-Xenyl )-Z^. ^-cyclohexenone

.....................

3-( 3-Xenyl )-.£s ^-cyclohexenone

.........................

71

3-( 2 - X e n y l )

.........................

73

2 _Cy C io}ieX 0non Q

1-Fhenyl-3-( 3 - x e n y l )-benzene (B) 1 - P h e n y l - 3 - ( 3 - x e n y l )-benzene

(A)

l-Pheny l- 3- ( 2- xe ny l) -b e nz en e (B) l - P h e n y i - 3 - (2 - x e n y l )-benzene

....................

(A)

71

75 76

....................

77

78

ii l-( 3 - X e n y l )- 3 -( 4 - x e n y l )-benzene

(A)

l-( 3 - X e n y l )-3-( 4 - x e n y l )-benzene

........

1 . 3 - D i - ( 3 - x e n y l )-benzene

................

..................

79 80 81

l - ( 4 - X e n y l ) - 3 - (2 - x e n y l )-benzene

(A)

............. ..

83

1 - ( 4 - X e n y l )-3-(2 - x e n y l )-benzene

(B)

................

84

l - ( 3 - Xenyl)-3-(2-xenyl)-benzene

(B)

85

1 - ( 3 - X e n y l )- 3 - ( 2 - x e n y l )-benzene

(A)

86

1 . 3 - D i - (2-xenyl)-benzene m-Cliloroiodobenzene m-Nitroiodobenzene

.............................

87

...................................

87

.............

89

3-Nitro-3 f-ch.lorobiphenyl

............................

89

3-Ch.loro-3 f-ami no biphenyl

............................

91

.............................

92

3-Iodo-3 T-chlorobiphenyl

3-( 3-Chloroph.enyl)- A ^ - c yc 1 ohexenone 3 , 3 f r- Dichloro-m-terphenyl

...............

.................

3-(3-(3 f- C h l o r o ) - x e n y l y l ^ - c y c l o b e x e n o n e 3, 3 T 1 ! T-Dichloro-m-quinqueph.enyl

....................

93 94 95 96

Wurtz reaction of 3,3 *ffT- d i c h l o r o - m - q u i n q u e p h e n y l .

97

U ltraviolet absorption

99

L I T E R A T U R E CITED

spectra

......................

101

INTRODUCTION A method ha d been d ev eloped earlier

In this laboratory

by T u c k e r 1 for the prep ar at io n of m e ta substituted d i a r y l benzenes f r o m the monoethyl ether of d i h y d r o r e s o r c i n o l . seemed pertinent that this synthetic route

It

should be extended

and the u t i li ty of this enol ether as a starting material for pre pa ri ng m et a di su bstituted benzenoid hy drocarbons be e x ­ ploited.

Therefore,

a series of polyphenyls was prepared by

the general reaction scheme shown below.

00 2s 5 R1MgX

substituents,

Pd-C

and R^, was varied to include all the p o s s i ­

ble combinations of phenyl, groups

In the final compound

Since the groups tion,

The nature of the

2-xenyl,

3-xenyl,

and 4-xenyl

(IV).

and B.£ possessed conjugate u n s a t u r a ­

it was' also a purpose of this research to Investigate

the ultraviolet light absorption of these substances In which the meta substituents cannot hybrid.

jointly enter into a resonant

This was done by d et er mi ni ng the a bsorption curves

in the ultraviolet region of the spectrum for each compound prepared.

These absorption curves not o n l y demonstrated the

prohibited resonance between m e t a substituents, but also brought out certain other fundamental facts applicable to

the theory of absorption of ultraviolet light by organic molecules.

These are discussed in a later section.

While this work was in progress,

it became apparent

that certain other avenues of approach were worthy of inves­ tigation.

To confirm further the interpretation of the

ultraviolet

spectra,

a series of compounds was prepared in

whi ch

was the tolyl group

(there b e i n g three possible

isomers)

and R 2 was the methyl

group,

three isomeric d i m e t h y l b i p h e n y l s .

thus resulting in

A still further extension

of the problem resulted in the p re paration of the three iso­ meric compounds of type II, in which R-j_ was a chlorophenyl group,

and also compounds of type

groups were the

and

II and IV in which the R

naphthyls.

HISTORICAL As has been stated In the Introduction,

earlier work in

this laboratory^- has shown the p o t e n t i a l i t y of d i h y d r o ­ resorc inol as a starting reagent for the pr ep ar at io n of m et a substituted aromatic hydrocarbons.

The thesis of Dr. Erwin

W. Tucker^- very thoroughly encompasses the hi storical b a c k ­ ground of the efforts of early workers to prepare the few polyphenyls which are known.

This histor ic al

search will not

be repe at ed here and the reader is r eferred to Dr. T u c k e r fs thesis. It should be of Interest, however,

to rev ie w the work

w h ic h has b een done on substituted polyphenyls.

Since this

thesis concerns itself w ith m e t a disubstituted benzenoid compounds, xenyl

w he rein the

substituents are either phenyl or

(the accepted nomencl at ur e for the biphenyl radical

w it h one free valence), primarily, recent

this histor ic al

compounds of this type.

and v e r y i nt eresting work

terphenyl,

this c ompound will be

summary will cover,

However,

in vi ew of some

on the chemistry of oincluded

in this portion of

the thesis. Schmidt and S c h u l t z ^ appear have reported the p r e p a r a t i o n of terphenyl.

to be the first workers to any derivatives of m-

A trinitro compound resulted from the treatment

of m-ter ph en yl with f u m i n g nitric acid. to prove Its structure. zinc and h ydrochloric

Ho attempt was made

This compound on reduction with

acid afforded a "288° m e l t i n g base".

A raonobromo and tetrabromo derivative h ave been r e ­ ported by Olgiati^;

the former substance was pr epared from

equimolar amounts of m-terphenyl and bromine

in carbon

d isulfide and the latter f ro m either m -terphenyl or f r om m on ob ro mo -m -t er ph en yl b y treating with excess bromine. Ox id at io n of the monobromo compound with chromic

oxide gave

either 4- or 6 - b r o m o - 3 - carboxydiphenyl which led Olgiati to conclude that the m on ob ro mo derivative would be 4 f-bromo-mterphenyl#.

Oxidation of the tetrabromo compound gave both

COOH

COOH

This nomenclature and that used throughout this thesis is in accordance with that recommended by Chemical Abstracts. s' 3"

3

3 3

m -Terphenyl

o-Terphenyl

4 -bromobenzoic

acid and 3 ,4 -dibromobenzoic

to conclude an original compound,

acid which seemed

3 " , 4 , 4 f,4"-tetrabromo-m-

terphenyl.

COOH

COOH

Br France, H e i l b o r n and H ey ^ have also studied the nitro derivatives of m- te rphenyl a tri-nitro-m-terphenyl.

by preparing a mono-,

a di-,

The mononitro compound was

and

shown

to be 4 1-nitro-m-terphenyl since on oxi da ti on it gave 2 nitro-5-carboxydiphenyl,

the structure of whic h was pr ov en

by an independent synthesis.

F o r the dinitro

compound they

COOH

proposed the structure

4, 6 f-dinitro-m-t©rphenyl since this

compound on oxidation gave 4-nitrobenzoic

acid,

indicating

the second nitro group was in the para p os it io n of the termi­ nal ring.

T hey p roposed the structure 4 , 4 " , 6 r-trinitro-m-

terphenyl for the trinitro derivative, b a s i n g this on anology but on no chemical evidence. f i rm ed by Wardner,

This work was e s s e n t ia ll y c o n ­

and L o w r y ^ who synthesized, the same nitro

d er ivatives and came to the same conclusions as to structure. T hey fu rther reported that the trinitro compound was r e s i s ­ tant to oxidation.

By catalytic

reduction of the mononitro

derivative these workers p repared the c o r r e s p on di ng monoamine (m.p.

64°).

F r o m this they prepared the hyd ro c hl or id e salt,

the acetyl derivative (m.p. 152°).

(m.p. 117°) and the benzoyl derivative

Dia zo ti za ti on of the amine fo llowed by c ou pl in g

w it h various naphthyl residues

gave colored compounds p o s s e s ­

sing dying properties. The mo no ch l or o and mon ob ro mo derivatives of m-terphenyl h av e b e e n synthesized b y Cook and Cook^ through the treatment of m-terp he ny l with the corres po nd in g h a l o g e n in the presence of iron.

In both cases the h a l o g e n was

4 f-position. the acid,

shown to be

In the

The 4 f-chloro-m-terphenyl was oxidized to yield

2 - c h l o r o - 5 - c a r b o x y b i p h e n y l , whose structure was

p r o v e n by synthesis f r o m 3 - n i t r o - 4 - a m i n o t o l u e n e .

This same

oxidative procedure was also employed to prove the structure of 4 1- b r o m o - m - t e r p h e n y l .

In an attempt to account for the

absence of any 4 - br o m o - 3 - c arboxybiphenyl products,

in the oxidation

they prepared 3-methyl-4-bromobipheny l and carried

out the same oxidative procedure on it.

All attempts failed;

the desired product was a pparently destroyed dur in g the oxi-

Cook and Cook^ have also prepared the 4 T-anino-mterphenyl and 4 f- i o d o - m - t e r p h e n y l .

The former was obtained

by treating 4 ^ c h l o r o - m - t e r p h e n y l with an excess of 28/£ hyd ro xy la mi ne

solution,

cuprous chloride,

calcium oxide,

and

copper for a period of thirty hours at 190° C. and 800 to 850 p.s.i. chloride,

The product was

isolated as the amine h y d r o ­

The free amine was liberated with pota ss i um

hydroxide.

Transf or ma t io n of this to the d ia z onium compound

and addition of po ta s s i u m iodide afforded the 4 T-iodo-mterphenyl The reaction of cyclohexene oxide with phenol in the presence of boron trifluoride has b e e n shown by Price and Mueller

8

to result In a small amount

terphenyl,

of 4,4 n-dihydroxy-m-

although the principle products of the reaction

were p -c yc lohexylanisole and 1,3-dianisyl cyclohexane. Similarly some 4 , 4"-dimethoxy-m-terpheny l Is obtained w hen cyclohexene oxide chloride.

is treated with anisolo and aluminum

Substitution of 1 ,2 -dichlorocyclohexane for

cyclohexene oxide

results In similar reaction products.

The

4 , 4 "-dihydroxy-m-terphenyl was reacted at 300° C. with zinc dust to give m-terphenyl. At the time of this writing,

Bradsher and Swerlick^ are

apparently In the process of a more comprehensive i n v e s t i g a ­ tion of certain reactions of m-terphenyl.

A pr el i mi na ry

report has indicated some Interesting results.

Bradsher

implied that hi s earlier work had shown that mo no ha logenation and n it ration resulted in substitution of the 4 f-position

while the F r i e d e l and Grafts reaction resulted in substitu­ tion on the 4-position.

In preparing the 4 1-cyano-m-ter-

phenyl by the reaction of crude monobromo compound with cuprous cyanide,

these workers obtained not only the expected

4 ’- c y a n o - m - t e r p h e n y l , but also a small nitrile fr ac ti on which yielded 4-carboxy-m-terphenyl on hydrolysis.

Also,

in study­

ing the benz oy la ti on of m-terphenyl by the Friedel and Crafts method,

they found that their product contained some 4 ’-

be nz oy l-m-terphenyl as well as the expected 4-benzoyl However,

wh en using the Perrier complex of benzoyl chloride-

a luminum chloride, tained,

isomer.

only the 4 ’benzoyl-m- te r ph en yl was o b ­

and this in 69% yield.

a i 2 c i 6 .2 G 6h 5coci

+

Perrier complexes w it h p-tolyl

sr CO

and m-tolyl chlorides also brought about 4 ’-position.

substitution in the

These workers also report the p re pa ra ti o n of

several n e w m-terphenyl derivatives,

but details have not yet

been published. o-Terphenyl Derivatives An extensive

investigation into the chemistry of o-ter-

phenyl has been initiated by Allen and co-workers with the result that a number of its fundamental reactions have been elucidated.

As Allen and Pingert-^-0 have pointed out,

the

few known derivatives of o-terphenyl prior to their i n v es ti ­ gation were compounds r es u lt in g from degradative

studies on

large and complex molecules.

after

A l len and Pingert,

re vi ew in g the earlier attempts to prepare o-terphenyl, found that the most

satisfactory m e t h o d involved a W u r t z - F u t t i g

re ac t i o n of chlorobenzene with sodium.

F r o m 2.5 kg.

of

chlorobenzene and 230 g. of sodium they were able to obtain 70 g. of o-terphenyl

(m.p.

58°).

The general r e a ct iv it y of the molecule

is des cr ib ed by

A l l e n and Pingert as being" along two m a i n chemical axes:

The 4- and 4 n-positions have been shown to be the most r e ­ active, while the 3 ’- and 4 '-positions are reactivity”.

"secondary in

This situation was borne out in such reactions

as h a l o g e n a t i o n and nitration. For

some reason it had b ee n speculated that such a m o l e ­

cule as o-terphenyl might permit the Kekule

structures of the m id d l e rang.

any such property, lysis fragments

isolation of one of the In an attempt to find

the mole cu l e was ozonized and the h y d r o ­

studied.

As seen below,

a preferred Kekule

structure would result in different products.

CHO a ~ H sCOCHO -h{ ° CHO

C 5H 5 C = 0 I C 6 H 5C = O

-h

CHO I CHO

It is not difficult to appreciate the problems involved in such a study when one sees that either or b o t h terminal rings m a y be attacked by the ozone also.

That this did occur was

quite obvious to Allen and Pingert since they were unable to i de nt if y In appreciable amounts any fragments other than glyoxal.

N o r were they able to reproduce these ozonolysis

experiments to any satisfaction. These

same workers have

shown that o-terphenyl Is c a p a ­

ble of rearrangement to various isomers under certain c o n d i ­ tions.

In anhydrous benzene with al uminum chloride,

o-

terphenyl first rearranges to m- te rphenyl and finally to p-terphenyl. is used,

If an equivalent amount of aluminum chloride

the results are more drastic;

among the products

formed are p-terphenyl and t r i p h e n y l e n e .

As the temperature

and c o nc en tr at io n of aluminum chloride are Increased,

con­

densation products predominate. Allen and P i n g e r t ^ have reported the acetyl, benzoyl, bromo,

and nitro derivatives of o-terphenyl.

workers expected,

acetyl chloride or acetic

As these anhydride c o m ­

bined w ith o-terphenyl In the presence of aluminum chloride

11. to give 4 -ac e t y l - o - t e r p h e n y l .

The structure was verified by

showing that this compound was identical with substance obtained f ro m a Wurtz reaction of o-iodobiphenyl with pbromoacetophenone.

Usin g sodium hypochlorite the acetyl COCH