The Preparation and Hydration Op Unsymmetrical

Home , Acetophenone, Benzonitrile, Phenylacetylene

THE PREPARATION AND HYDRATION OP UNSYMMETRICAL

DIARYL ACETYLENES

DISSERTATION

Presented in Partial Fulfillment of the Requirements

for the Degree Doctor of Philosophy in the Graduate

School of The Ohio State University

DONALD EUGENE REID, B.S.

The Ohio State University

1927

Approved by:

d d l M M S \ Adviser Department of Chemistry Acknowledgement

To Doctor Melvin S. Newman the author wishes to express his deep appreciation for suggesting this problem and for the personal friendship and inspira tional guidance throughout this investigation.

I would also like to thank the Eastman Kodak

Company for their fellowship which I held in 195^-1956.

ii. Table of Contents

Introduction

I. Purpose ...... 1

II. P l a n ...... 1

III. Historical ...... 1

IV. Present work ...... S

Experimental

I. Preparation of ketones

A. lj.'--Chloro-2(o-chlorophenyl)acetophenone . . 6

1 . p-Chlorobenzonitrile...... 6

2 . o-Chlorobenzylbromide ...... 7

3» Reaction of o-chlorobenzylmagnesium

bromide and p-chlorobenzonitrile .... 7

B. 2 '-ChlorO“2 (p-chlorophenyl)acetophenone . « 8

1 . o-Chlorobenzonitrile ...... 8

2 . p-Chlorobenzylbromide ...... 8

3 . Reaction of p-chlorobenzylmagnesium

bromide and o-chlorobenzonitrile .... 9

C. I4.•-Chloro-2-phenylacetophenone ...... 9

D. 2(p-Chlorophenyl)acetophenone ...... 10

E. 2 (o-Chlorophenyl)acetophenone ...... 11

P. 2 ’-Chloro-2-phenylacetophenone ...... 11

G. 3 '-Chloro-2-phenylacetophenone ...... 12

1 . m-Chlorobenzonitrile ...... 12

iii. iv»

2. Reaction of benzylrnagnesiuni chloride

and m-chlorobenzonitrile ...... 13

H. 2 (m-Chlorophenyl )acetophenone ...... 13

1 . m-Chlorobenzyl bromide •••••••••13

2« Reaction of m-chlorobenzylmagnesium

bromide and benzonitrile •••••••• II4.

IIo Preparation of diaryl acetylenes

(o-Chlorophenyl)p-chlorophenylacetylene . • II4.

1^ Dehydrohalogenation of 1-p-chlorophenyl-

2-0-chlorophenyl-l,l-dichloroe thane • • ll).

2.» Unsuccessful attempt via ^(o-chloro-

phenyl)5(p-chlorophenyl)3-nitroso-2-

oxazolidone •••••• ...... • 1^

B, (p-Ghlorophenyl )phenylacetylene ...... 1?

(o-Chlorophenyl)phenylacetylene •••*•• 18

1^ o-Chlorobenzil •••••••••••••18

2# o-Chlorobenzil dihydrazone ••••••• I9

3. Oxidation of o-chlorobenzil dihydrazone I9

[j.. Unsuccessful attempts to prepare

(o-chlorophenyl)phenylacetylene • • • • 20

(m-Chlorophenyl)phenylacetylene ...... *21

1, m-Chlorobenzil ••••••••.••••21

2, m-Chlorobenzil dihydrazone ...... 22

3, Oxidation of m-chlorobenzil dihydrazone 22 V,

E, Dlphenylacetylene...... 23

1. Benzll dihydrazone ...... 23

2, Oxidation of benzil dihydrazone ♦ . . . 23

P. Di-p-methoxyphenylacetylene...... 2lj.

1. Preparation of anisil via anisoin . . . 2^

2» Oxidation of anisil dihydrazone « • . * 2)|.

III. Hydration of diaryl acetylenes

A. General method ..,.*...... ,26

B. Tabulation of conditions and results . . . 28

G. Calculation of r e s u l t s ...... 36

IV. Ultraviolet spectra of pure ketones and

pure diaryl acetylenes ...... 38

Discussion of results

I. Methods of synthesis ...... Ip.

II. Analytical method ...... 50

III. Hydration of diaryl acetylenes ...... 55

Summary ...... 72

Autobiography...... ll\. List of Tables

Table

I Hydration of 0.2 g. of (p-chlorophenyl)phenyl-

acetylene at 90-95° and the absorbances of the

resulting mixture ...... 29

II Molar extinction coefficients of pure (p-chloro-

phenyl)phenylacetylene, 2(p-chlorophenyl)aceto-

phenone, and ^'-chloro-2-phenylacetophenone . . . 30

III Results of (p-chlorophenyl)phenylacetylene

hydration calculated at 228 mu, 26o mu, and

28ij. m u ...... 30

IV Absorbances of hydration mixtures from (o-chior6-

phenyl)p-chlorophenylacetylene 31

V Molar extinction coefficients of pure (o-chloro

phenyl )p- chlorophenylacetylene, - chloro-2 ( o-

chlorophenyl)acetophenone, and 2 '-chloro-2(p-

chlorophenyl)acetophenone ...... 32

VI Results of the hydration of (o-chlorophenyl)p-

chlorophenylacetylene ...... 33

VII Absorbances of a known solution of 70% 2(o-

chlorophenyl)acetophenone and 30^ 2'-chloro-2-

phenylacetophenone and of a solution of the

hydration mixture from (o-chlorophenyl)phenyl-

acetylene in ethanol ......

V i . vil.

Table

VIII Absorbances of a known solution of 2(m-

chloropb.enyl)acetophenone and 3'-chloro-2-

phenylacetophenone and of a solution of the

hydration mixture from (m-chlorophenyl)phenyl-

acetylene In ethanol ...... 35

IX Yields and physical constants of 2-phenyl-

acetophenones ...... i|^2

X Reaction conditions, yields, and physical

constants of diaryl acetylenes prepared by the

silver lon-trlethylamlne method i(.6

XI Comparison of the found direction of hydration

of diaryl acetylenes with the direction of

hydration predicted from the directive effects . 6? List of Figures

Figure

I U.V. Spectra of Chloro-substltuted 2-

Phenylacetophenones ...... 38

II U.V. Spectra of Chloro-substltuted 2-

Phenylacetophenones ...... 39

III U.V, Spectra of Chloro-substltuted

Dlphenylacetylene ...... I4.O

vlll THE PREPARATION AND HYDRATION OP UNSYMMETRICAL

DIARYL ACETYLENES

Introduction

I. Purpose

The purpose of the work herein described was to study the directive effects of a chlorine atom on the hydration of unsymmetrical diaryl acetylenes and to determine if these directive effects were additive.

II. Plan

The plan of this research was to synthesize some pure unsymmetrical chloro-substituted diaryl acetylenes, to hydrate these acetylenes, to measure the proportions of the two isomeric ohloro-substituted phenyl benzyl ketones formed from each acetylene, to study the directive effects of the chloro atoms, and to determine if these directive effects were additive.

III. Historical

The hydration of several unsymmetrical diaryl acety lenes has been reported. The acid-hydration of (m-nitrophenyl)p-nitrophonylacetylone has been reported^ to be very difficult and to yield only m-nitrophenyl p-nitrobenzyl ketone. Harrison explained that the acetylenic carbon atoms are under a strong positive field, which

1, H, A. Harrison, J. Chem. Soc. 1926, 1232. 1. 2. inhibitâ reactivity towards positive ions at both centers»

The electrons of the acetylenic bond will be displaced in the indicated direction^ due to the resonance of the p- nitrophenyl group and addition of water would be expected to yield only m-nitrophenyl p-nitrobenzyl ketone*

^ m-N02C6H^C=GG6H^N02-p — » m-N02G6H^G0GH2G&H^N02-p

On the other hand the acid-hydration of m-acetylaminophenyl p-acetylaminophenyl acetylene has been reported^ to be very easy and to yield only m-acetylaminobenzyl p- acetylaminophenyl ketone. Harrison stated that because of the conjugation of the two acetylamino groups with the respective benzene nuclei, a strong negative field was produced in the region of the acetylenic carbon atoms*

These acetylenic carbons were consequently easily attacked by positive ions and addition of water took place with great ease. However, the electrons would be displaced more in the indicated direction due to the resonance effect

1 . Throughout the text the notation 4--- > is used to indicate that the triple bond is polarized with a frac tional negative charge adjacent to the arrowhead and a fractional positive charge adjacent to the arrow tail#

2. H. A. Harrison, J. Chem. Soc» 1926, 1232. 3. of the p-acetylamlno group and the hydration would be expected to yield only m-acetylaminobenzyl p-acetylamino phenyl ketone.

^— h m-0H3C0NHC6H^0=CC6H^NHC0CH2-p-^m-GH2C0NHC6H^CH2C0G6H^NHC0CH^p

The acid-catalyzed hydration of 2-phenethynyl pyridine is reported^»^ to give a yield of 2-phenacylpyridine.

The inductive effect of the nitrogen atom or the strong inductive effect of the protonated nitrogen atom would dis place the electrons of the acetylenic bond in the indicated direction and hydration would be expected to yield only

2-phenacylpyridine• -----> GaH^GOGEgG^H^N

Analogous to this last hydration is the hydration of 2,6- diphenethynyl pyridine to 2,6-diphenacylpyridine,2 of 2- phenethynyl quinoline to 2-phenacylquinoline,^ and of 2- phenethynyl quinoline-lj.-carboxylic acid to 2-phenacylquinoline-l}. carboxylic acido^

1, E. C. Kornfield, Ph.D. Dissertation, Harvard University, 19^6.

2 . G. H. Boehringer Sohn A.G., G. Scheuing and L, Winterhalder, Ger. Patent Mar, 22, 193h* 4 . It can be seen that the hydration of unsymmetrical diaryl acetylenes overwhelmingly favors one of the two possible isomers when the directing group is either a strongly polar group or a strongly resonating group.

The resonance effect of the para nitro group of (m- nitrophenyl)p-nitrophenylacetylene controlled the hydra tion, since the inductive effects of the m-nitro and the p-nitro groups would essentially balance each other.

The resonance effect of the p-acetylamino group of (m- acetylaminophenyl)p-acetylaminophenylacetylene controlled the hydration, since the inductive effect of the m- acetylamino and of the p-acetylamlno groups would essen tially balance each other. However, in the hydration of

2-phenethynyl pyridine it appears that the inductive effect of the protonated 2-pyrldyl group directed the hydration. Thus either the inductive effect or the resonance effect of a group can control the direction of hydration of an unsymmetrical diaryl acetylene. It was thought of interest to study the directive effects

of additional groups in the hydration of unsymmetrical

diaryl acetylenes and to determine if these effects were

additive. A systematic study of the directive effects

of the chloro, methoxy, and nitro groups was originally

planned. However, unforeseen difficulties in the prepar

ation anlpunification of the necessary diaryl acetylenes 5. limited the present work to a study of the directive effects of the chloro groups*

IV. Present work

Pour unsymmetrical ohloro-substituted diaryl acety lenes have been prepared and the eight chloro-substituted phenyl benzyl ketones, which result from the hydration of the diaryl acetylenes, have also been prepared by an inde pendent route. The four acetylenes have been hydrated and the product proportion of the two possible isomeric ketones have been measured in each case, A study of the additivity of the directive effects of the chlorine atom has been made, A new synthetic method for the preparation of di

substituted acetylenes has been found. Experimental

I. Preparation of ketones,

A, i|. ’-Chloro-2 ( o-chlorophenyl) ace tophenone

1 , p-Chlorobenzonitrile

After diazotized p-chloroaniline (12? g,, 1.00 mole) was reacted with cuprous cyanide^ and treated in the usual m a n n e r , 2 steam distillation of the resulting black material afforded 82,^ g, (6o^) of light yellow p-chlorobenzonitrile, m.p, 87-89° (lit.3 9^--96°). Previous at tempts to prepare p-chlorobenzonitrile by reacting p- chlorobenzamide, prepared in good yield via the acid chloride and concentrated ammonium hydroxide at 0°, with the double salt, NaCl'AlGl^, at 230° for one houjA, with polyphosphoric acid at 13^° for six hours, with thionyl

chloride and benzene at 70-75® for twelve hours, and with phosphorus pentachloride at 100° for one hour and at II4.5® for an additional hour, all were unsuccessful.

1 . Organic Synthesis, Coll. Vol* I, John Wiley & Sons, Inc., New York, N. Y. (I9I4-I)» p.5l^«

2. The phrase "treated in the usual manner" used through out the experimental means that the organic solvent layer was washed successively with water, either dilute acid or dilute base where the reaction media was basic or acidic, saturated sodium chloride solution, filtered through an hydrous magnesium sulfate, and the solvent stripped.

3. H. Meyer and A. Hofmann, Monatsh. 38, 350(1917)•

1|. J. F. Norris and A. J. Klemka, J. Am. Chem. Soc. 62, 1)4.32(1940). 6» 7. 2 . o-Chlorobenzylbromide

o-Chlorotoluene (60 g., 0*i|-75 mole) was heated to

114.0-150° and 90 g* (0.56 mole) of bromide and approximate ly 2 g. of benzoyl peroxide were added portionwise over a period of thirty minutes. The color of the reaction mixture changed from cherry red to light yellow during an additional hour of heating. After cooling the reaction and pouring it into water, the organic layer was treated in the usual manner and distilled to yield 90.3 g. (92.7^) of o-chiorobenzyl bromide, b.p. 103-10^° at 10 mm. (lit.^

102° at 9 mm.).

3. Reaction of o-chlorobenzylmagnesium bromide

and p-chlorobenzonitrile

To a stirred suspension of 6 g. (0.25 mole) of magnesium in 150 ml. of dry ether was added 25 g. (0.125 mole) of o-chlorobenzylbroraide in 100 ml. of dry ether over a period of one hour followed by the addition of

13*7S g« (0.1 mole) of p-chlorobenzonitrile in 100 ml, of dry ether over ten minutes. After refluxing for six and one-half hours and standing overnight, the reaction mix

ture was poured into 200 ml. of 10^ sulfuric acid, the

ether was evaporated, and the resulting solution heated

to 60° for one hour. The organic layer was treated in

1 . J. B. Shoesmith and R. H. Slater, J. Ghem. Soc. I926, 219, 8. the usual manner and the product was recrystallized from ethanol to yield 20 g. (7S%) of l4-*-chloro-2(o-chlorophenyl)- acetophenone, m.p. 103-107°» Further recrystallizations produced colorless needles, m.p. 107*^^108.^0 (lit.^ 108°)o B. 2 '-Chloro-2 (p-chlorophenyl)acetophenone

1 . o-Chlorpbenzonitrile

A dioxane solution of o-chlorobenzoyl chloride, prepared from o-chlorobenzoic acid (1^6 g., 1.00 mole), phosphorus pentachloride (208.5 g., 1.00 mole), and benzene in the usual fashion, was added with vigorous stirring to

500 ml. of concentrated ammonium hydroxide at 0° to yield o-chlorobenzamide. This amide was dried, refluxed for three days with 357 g* (3*00 moles) of thionyl chloride,^ and distilled to yield II9 g. (Q6%) of colorless o-chlorobenzonitrile, b.p. 9^° at 7 mm., m.p. 1|.1-1{.3° (lit.3 ^2-^3°)*

2. p-Chlorobenzylbroraide

p-Chlorotoluene (I90 g., 1.5 moles) was heated to

Iif0-l50° and 2l|.0 g. (1.5 moles) of bromine and approxi mately 2 g. of benzoyl peroxide were added portionwise over forty-five minutes. The reaction mixture was heated for an additional hour, during which the color changed from

1 . S. S. Jenkins and E. M. Richardson, J. Am. Chem. Soc* 1618(1933)*

2* Hooker Chemical Company, technical grade.

3. P. J. Montagne, Rec, trav. chim. 50(1900)* 9. red to yellow, then cooled and filtered to yield 133 g#

(43^) of p-chlorobenzyl bromide, m.p. (lit*^ 51®)»

3» Reaction of p-chlorobenzylmagneaium bromide

and O"chlorobenzonitrile

To a stirred suspension of 6 g, (0.25 mole) of magnesium in 170 ml. of dry ether was added 25*7 g» (0.125 mole) of p-chlorobenzyl bromide in 100 ml. of dry ether over 1.5 hours. After the addition of 13*75 g. (0.1 mole) of o-chlorobenzonitrile in 100 ml. of dry ether, the reac tion mixture was refluxed for six hours. The reaction mixture was then cooled, poured into 200 ml. of 10^ sul furic acid, the resulting solution heated to 60® for one hour and the organic layer treated in the usual manner to

yield 19*1 g* {12%) of crude product. This product was

recryatallized three times from ethanol to yield 2 '-chloro*

2 (p-chlorophenyl)acetophenone, m.p. 63-65° (lit*^ 65°). C. l|.'-Chloro-2-phenylacetophenone

Phenylacetyl chloride, prepared by refluxing phenyl-

acetic acid (lll^. g«, 0.8^ mole), thionyl chloride (I60 g.,

1.3^1- moles), and 300 ml. of benzene for ten hours and

removing the benzene and excess thionyl chloride at the

pump, was added to a stirred slurry of aluminium chloride

1 . J. B« Shoesmith and R. H. Slater, J. Chem. Soc. 1926, 219.

2. S. S. Jenkins and E, M. Richardson, J. Am. Chem. Soc. 1618(1933). 10.

(133*5 g»> 1.00 mole) and chlorobenzene (I4.OO g., 3*55 moles) over thirty minutes. The reaction mixture was heated to 70° for one and one-half hours, cooled, poured into 500 ml. of ice containing 50 ml. of concentrated hydrochloric acid and the resulting solution extracted with ether-benzene. After treatment of the organic layer in the usual manner, the crude brown solid was recrystal lized from ethanol to yield 13I g. (68^) of l|’-chloro-2- phenylacetophenono, m.p. 87-95°* Three further recrystal lizations from alcohol produced colorless scales, m.p#

106,0-107.0° (llt.l 107.5®). D. 2 (p-Chlorophenyl)acetophenone

p-Chlorobenzyl bromide (llj.3 g., O.7O mole) (see p. S’ )

in 700 ml. of dry ether was added to a stirred suspension

of 36 g. (1*5 moles) of magnesium in 300 ml. of dry ether

over three hours and fifteen minutes. After 72 g. (0.70

moles) of benzonitrile in 500 ml. of dry ether were added

over thirty minutes, the reaction mixture was refluxed for

six hours, cooled, and poured into 500 ml. of 10^ sulfuric

acid. After the ether evaporated, the hydrolysis mixture

was heated to 60° for thirty minutes, extracted with ether-

benzene and the resulting organic layer treated in the

usual manner. One recrystallization from ethanol yielded

1 . S. S. Jenkins and E. M. Richardson, J. Am. Chem. Soc. ii, 1618(1933). 11.

112.2 g. (70^) of 2(p-nhlorophenyl)acetophenone, m.p.

136-138®. Further recrystallizations produced thin color less plates, m.p. 137.6-138.2° (lit.^ 138°).

E, 2 (o-Chlorophenyl)acetophenone

o-Chlorobenzylhromide (l62*5 g., 0.79 mole) (see p. 7 ) in 560 ml. of dry ether was added to a stirred suspension of 28.8 g. (1.20 moles) of magnesium in 21^.0 ml. of dry ether over three hours, followed by the addition of 82.5 g. (0.80 mole) of benzonitrile in 1^.00 ml, of dry ether over forty minutes. The reaction mixture was refluxed for six hours, cooled, and poured into ij-OO ml. of 10^ sulfuric acid. After the ether evaporated, the hydrolysis mixture was heated to 60° for thirty minutes, was twice extracted with ether and the combined organic layers treated in the usual manner. The product was recrystal lized from petroleum other, b.p. 90-97° (Skellysolve C), to yield 100.0 g, (55^) of 2 (o-chlorophenyl)acetophenone, m.p, 63-67°. Further recrystallizations from Skellysolve

0 yielded white needles, m.p. 69*0-70.5° (lit.^ 70.5°)*

P, 2 •-Ghloro-2-phenylacetophenone

Benzyl chloride (126.5 g*» 1.00 mole) in 700 ml. of dry ether was added to a stirred suspension of 36.0 g.

1, S, S, Jenkins and E. M. Richardson, J, Am. Ohem. Soc. 1618(1933)* 12.

(1.5 moles) of magnesium in 100 ml. of dry ether over three hours, followed by the addition of lig.O g. (0.86 mole) of o-chlorobenzonitrile in 600 ml. of dry ether over forty minutes. The reaction mixture was refluxed for six hours, cooled and poured into 500 ml. of 10^ sulfuric acid.

After the ether had evaporated, the resulting solution was

heated to 60° for thirty minutes, extracted with ether,

the organic layer treated in the usual manner, and the

product distilled to yield ll^O g. ill%) of 2 '-chloro-2- phenylacetophenone, b.p. 166-169° at 3 mm. A sample of

this product was fractionated on a 6-inch column packed

with glass helices to yield a middle fraction of very pale

yellow liquid, b.p. ll4ij.-l[|.6° at 1 mm. (lit.^ 176-178° at

5 mm. ).

G. 3 '-Chloro-2-phenylacetophenone

1. m»Chlorobenzonitrile

After diazotized m-chloroaniline (127*5 g*» 1.00

mole) was reacted with cuprous c y a n i d e , ^ the product was

treated in the usual manner and distilled to yield 70 g,

(51?^) of m-chlorobenzonitrile, b.p. 103-106° at I9 mm. (lit.3 93.5-9^^10 at II4. mm.).

1 . S. S. Jenkins and E, M. Richardson, J. Am. Ohem. Soc. gi, 1618(1933).

2. Organic Synthesis, Coll. Vol. I, John Wiley & Sons, Inc., New York, N.Y. (I9ip.;, p.5liv*

3. K. W. P. Kohlrausch and A.Bongratz, Monat. 65,199(1935). 13. 2 . Reaction of benzylmagnesium chloride and

m-chlorobenz onitrile•

To a stirred suspension of 9*6 g, (0,1}. mole) of magnesium in 100 ml, dry ether was added 2$,3 g« (0.2 mole) of benzyl chloride in 100 ml, of dry ether over forty-five minutes, followed by the addition of 20 g,

(0 ,ll|.5 mole) of m-chlorobenzonitrile in 200 ml, of dry ether over fifteen minutes. After refluxing for six hours, the reaction mixture was poured into 300 ml, of 10^ sulfur

ic acid, the ether was evaporated, and the resulting solu

tion heated to 60° for one hour. The organic layer was

treated in the usual manner and the product was recrystal

lized from petroleum ether, b,p, 65-69° (Skellysolve B),

to yield 25,5 g. (765^) of 3 '-chloro-2-phenylacetophenone,

m,p, 58-60°. Further recrystallizations from Skellysolve

B produced colorless crystals, m,p, 6o«i}.-6l,6° (lit,^ 62°)*

H, 2 (m-Chlorophenyl)acetophenone

1 * m-Chlorobenzylbromide

m-Chlorotoluene (126,5 g»> 1,00 mole) was heated

to 130-ll)-0° and illuminated with a strong light source

while 176 g, (1,10 mole) of bromine was added over twenty

minutes. During an additional ten minutes of heating the

color of the reaction changed from red to light yellow*

1 , S. S, Jenkins, J. Am, Chem. Soc, 5^ 703(1933). Distillation yielded 15I4. g. (75^) of m-chlorobenzyl bromide, b.p, 117-119° at IS mm. (lit,^ 109° 10 mm.). 2. Reaction of m-chlorobenzylmagnesium bromide

and benzonitrile.

To a stirred suspension of 2l|. g. (1,00 mole) of magnesium in 300 ml. of dry ether was added 15I4. g. (0,75 mole) of m-chlorobenzyl bromide in 300 ml. of dry ether over one and one-half hours, followed by the addition of

78 g. (0,75 mole) of benzonitrile in i|.00 ml. of dry ether over twenty-five minutes. After refluxing for six hours, the reaction mixture was poured into 3OO ml. of 10% sul furic acid, the ether was evaporated and the resulting solution heated to 60° for one hour. The organic layer was treated in the usual fashion and the product dis tilled to yield 80 g. (1|.7^) of 2(m-chlorophenyl)acetophen one. Two recrystallizations from ethanol yielded the pure ketone, m.p. ^1,8-^2.8° (lit,^ ^3°).

II. Preparation of diaryl acetylenes

A, (o-Chlorophenyl)p-chlorophenylacetylene

1. Dehydrohalogenation of 1-p-chlorophenyl-

2-o-chlorophenyl-l,l-dichloroethane

After refluxing 5*3 g. (0.02 mole) of ^/-chloro-

1 . J. B, Shoesmith and R. H. Slater, J. Ohem. Soc. 1926, 218.

2, S. S. Jenkins, J, Am. Chem. Soc. 2896(1933)♦ 15. 2 (o-chlorophenyl)acetophenone, 10 g. (0 »0i^.8 mole) of phosphorus pentachloride, and ^0 ml. of benzene for four hours, the reaction mixture was poured into water, ex tracted with ether, and the organic layer treated in the usual manner. The resulting colorless solid was not char acterized, but was dissolved in 25 ml. of absolute alcohol, added to a solution of 3,1^ g. (0.05 mole) of sodium ethoxide in 50 ml. of absolute alcohol and refluxed for two and one-half hours. After pouring the reaction mixture into water, extracting the resulting solution with ether, and treating the organic layer in the usual manner, a product was obtained which on decolorizing with charcoal and recrystallizing twice from ethanol-water yielded (o- chlorophenyl)p-chlorophenylacetylene, m.p. 62.5-64^ 5°.

Anal. Calcd. for G^^HQClg: G, 68.0 ; H, 3.2 ; Cl, 28.7.

FoundG, 67.9; H, 3.3; 01, 28.5 .

2 . Unsuccessful attempt via 5 (o-chlorophenyl)-

5-(p-chlorophenyl)3-nitroso-2-oxazolidone2

o-Ghlorobenzoyl chloride, prepared from l56 g.

(1.00 mole) of o-chlorobenzoic acid, 220 g. (I.06 moles) of phosphorus pentachloride, and 3OO ml. of benzene in the

1 . All analyses, unless otherwise stated, were preformed by the Galbraith Laboratories, Knoxville, Tennessee.

2. M. S. Newman and A. Kutner, J. Am. Ghem. Soc. 73* 4199(1951). l6.

usual fashion, was added to a vigorously stirred slurry of

ll+O g. (1.0^ moles) of aluminum chloride and 636 g. (5»^5 moles) of chlorobenzene over one hour at $0^» After re

fluxing for one and one-half hours, the reaction mixture

was poured into 2 kg. of cracked ice containing 75 ml. of

concentrated hydrochloric acid, the resulting solution

extracted with ether, and the organic layer treated in the

usual manner. Distillation afforded 2Li4 g. (97^)of

dichlorobenzophenone, b.p. l60.^-l6l.^° at 2 mm., which was

recrystallized three times from Skellysolve B to yield I83

g. {72%) of colorless rods, m.p, 66.0-66.5° (lit*^ 66.5-

67.0°).

After 66 g. (1,00 mole) of previously sanded zinc foil

was added to a thoroughly dry mixture of 150 g. (O.60 mole)

of 2,^/-dichlorobenzophenone, 122 g. (O.8O mole) of methyl

cA-bromoacetate, and 350 ml. of dry benzene, the reaction

refluxed vigorously of its own accord for thirty minutes

and was then refluxed for an additional thirty minutes*

The reaction mixture was cooled and poured into 250 ml. of

10^ sulfuric acid, the resulting solution extracted with

ether-benzene and the organic layer treated in the usual man

ner. On attempted distillation the product darkened and tiae

distillate showed unsaturation to bromine. All attempts to

1 , J. P. Norris and W. C. Twieg, Am. Chem. J. 30, 397 (1903). 17. to obtain a solid product by crystallization failed.

After refluxing 100 g. (0,31 mole) of the crude

Reformatsky product and ^0 g. (1,25 moles) of anhydrous hydrazine in 100 ml, of methanol for one hour, the solvent was evaporated to yield a very tarry material. The solid portion of this material was dissolved in ethanol, passed

through an alumina column and the resultant solution con

centrated to yield a yellow solid, which was recrystallized

three times to yield the colorless hydrazide of ^-hydroxy-

(o-ohlorophenyl) - (p-chlorophenyl)propionic acid, m.p.

166-167°. Anal, Calcd, for 01^8^^02^2012" 8, ii-*3î 8, 8 . 6 , Pound:^ 0, 55»3> 55*5 î 8, ^ , 6 , i|.,8; N, 8 . 9 ,

8 ,7 . This synthetic sequence was abandoned since the yield

of hydrazide from 2,i|.*-dichlorobenzophenone was less than

1% of theory,

B, (p-Chlorophenyl)phenylacetylene

After heating 10 g. (0,0^35 mole) of I}.chloro-2-

phenylacetophenone and 10 g. ( 0 , Ol|.8 mole) of phosphorus

pentachloride for three hours at 6o°, the reaction mixture

was distilled to yield 8,0 g, of a colorless solid, b,p,

183° at 5 mm. This solid was not characterized but was

refluxed for four hours with 6.7 g. (0,07 mole) of sodium

1, This analysis was performed by the Microanalytical Laboratory of the Chemistry Department of The Ohio State University, Columbus, Ohio 18. t-butoxlde in 100 ml. of t-butyl alcohol. After pouring the reaction mixture into water, the resulting solution was extracted with ether and the organic layer treated in the usual manner to yield $.l| g. (60^) of crude product.

After three recrystallizations from ethanol, pure (p- chlorophenyl)phenylacetylene, m.p. 8l.$-83'0°, was obtained.

Anal. Galcd. for ; 0, 79*1 ; H, Ij..3 î Cl, l6 .6 .

Pound: C, 79*1 ; H, Gi, l6.k.

C, (o-Chlorophenyl)phenylacetylene

1. Preparation of o-chlorobenzil

After heating 20.0 g. (0.0868 mole) of 2 (o-chlorophenyl)acetophenone, 15*^ g. (0 .1^ mole) of selenium dioxide and l|.0 ml. of acetic anhydride to I30-II1.O® for four hours, the reaction mixture was filtered, poured into water, the resulting solution extracted with ether, and the organic layer treated in the usual manner to yield yellow o-chlorobenzil, m.p. 38-I4.2® (lit.l ^7 *2-^9 .0°). Alternatively this diketone was obtained in similar yield by stirring

10 g. (0.0lj.3lj. mole ) of 2 (o-chlorophenyl )acetophenone and

10 g. (0,063 mole) of potassium permanganate in ll).0 ml. of

1:1 water-pyridine for seven hours at room temperature while

controlling the basicity of the solution with periodic

additions of carbon dioxide.

1 . E. L. Shapiro and E. I. Becker, J. Am. ^hem. Soc. 75* 4769(1953). 19. 2. Preparation of o-chlorobenzil dihydrazone

o-Chlorobenzil was refluxed for eighteen hours with 6,^ g. (0.2 mole) of anhydrous hydrazine, 2 ml. of glacial acetic acid and 2^0 ml. of ethanol. The reaction mixture was cooled and filtered to yield l6.3 g. yield from 2 (o-chlorophenyl)acetophenonej| of a white crystalline solid, m.p. 230-237° dec. Further recrystal lization from acetonitrile yielded the pure dihydrazone of o-chlorobenzil, m.p. 23^^236° dec. Anal. Galcd. for

Gl^HljN^Cl: C, 6l.6; H, N, 20.5 , Cl, 13.0 . Pound:

G, 61.6, 61.6; H, 5 .0, 5.0 ; N, 2 0 . l^., 2 0 . 1+; c i , 12.6, 12.7.

3. Oxidation of o-chlorobenzil dihydrazone

To a stirred solution of 10 g. (0.037 mole) of o-

chlorobenzil dihydrazone in 200 ml. of N-methylpyrrolidone was added 50 g. (0*22 mole) of silver benzoate in three portions followed by the addition of 25 ml. of triethyl-

amine in three portions. The theoretical quantity of

nitrogen was evolved over four hours. After the reaction

mixture was filtered and poured into water, the resulting

solution was extracted with ether, the organic layer

treated in the usual manner, and the product distilled to

yield 2.5 g* (32^)^ of (o-chlorophenyl)phenylacetylene.

1. The total yield is not known. This yield is the middle cut which was taken as an analytical sample to insure purity. 20. b.p. li|5-li4-7® at 3 mm. Anal. Galcd. for C^|^HgCl; C,

79.1; H, ^.3; Cl, 16.7. Found: G, 78.9 , 79.1; H,

Gi, 1 6 .5 , 1 6 .iv,

I).. Unsuccessful attempts to prepare

(o-chlorophenyl)phenylacetylene

Attempts to prepare (o-chlorophenyl)phonylacety- lene by reaction of 1-chloro-2 (o-chlorophenyl)i-phenylethylene, prepared by the reaction of 2 (o-chlorophenyl)- acetophenone, phosphorus pentachloride and benzene in the usual fashion, with a large excess of sodium ethoxide in ethanol at 78° for twenty-three hours, with a large excess of sodium t-butoxide in t-butyl alcohol at 83° for twenty- four hours, with a large excess of phenyl lithium^ in

diethyl ether at room temperature for one week, and with a large excess of sodium ( /^-aminoethyl)amide in ethylene-

diamine at 117° for fifty-two hours, all failed. An

attempt to convert l-bromo-2-o-chlorophenyl-2-phenyl-

ethylene, prepared by an adaption of known methods for

l-bromo-2,2-di-m-tolylethylene,^ to (o-chlorophenyl)-

phenylacetylene with potassium amide in liquid ammonia

resulted in removal of the aromatic chlorine atom. Finally,

an attempt to convert 2 (o-chlorophenyl)l-phenyl-l-carboxy-

1 . Organic Synthesis 2^, 83(19^3).

2o G. H, Coleman, W. H. Holst, and R. D. Maxwell, J. Am, Ghem. Soc. ^8 , 2310(1936 ). 21. ethylene, m.p. 177-178®» prepared in 91^ yield by reaction of o-chlorobenzaldehyde, sodium phenylacetate, and acetic anhydride at ll|.0° for seventeen hours, to the corresponding dibromo compound and then to (o-chlorophenyl)phenylacetylene failed due to the failure of the bromination step.

D, (m-^hlorophenyl)phenylacetylene

1. m-Chlorobenzil

After heating 10 g. (0,0^3^ mole) of 3*-chloro-2- phenylacetophenone, 10.3 g« (0.08 mole) of selenious acid, and 20 ml* of acetic anhydride to 130-1^0° for three hours, the reaction mixture was filtered, poured into water, the resulting solution extracted with ether, and the organic layer treated in the usual manner to yield a yellow pro duct, m.p. 86-90°. Two recrystallizations from ethanol yielded pure m-chlorobenzil, m.p. 88.8-89*8° (lit*^ 86.0°).

Anal. Galcd. for G^^HgOgGl; C, 68.7 ; H, 3 .7 ; Cl, l^.So

Pound; G, 6 8 .5, 68 .5 ; H, 3.9, 3.7 ; GI, 1^.3 , 1^.5 . After

heating a glacial acetic acid solution of this product and

o-phenylene diamine for fifteen minutes on a steam bath,

the solution was cooled and filtered to yield a colorless

solid, m.p. 110-113°. Two recrystallizations from ethanol

yielded pure 2(m-chlorophenyl)3-phenylquinoxaline, m.p#

113.0-11^^2°. Alternatively, m-chlorobenzil was obtained

1. M. T. Clark, E. C, Hendley, 0 . K. Neville, J. Am. Ghem. Soc. %%, 3280(1955). 22.

in similar yield by stirring 5 6» (0.022 mole) of 3

chloro-2-phenylacetophenone and 5 g. (0.032 mole) of

potassium permanganate in 100 ml. of 1:1 water-pyridine

for six hours at room temperature while controlling the

basicity of the solution with periodic additions of

carbon dioxide.1

2 . m-Chlorobenzil dihydrazone

^fter refluxing 21.2 g. of m-chlorobenzil (0.0868

'mole), 8 g. of anhydrous hydrazine, 2 ml. of glacial acetic

acid, and 100 ml. of ethanol for twelve hours, the reaction

mixture v/as cooled and filtered to yield l6.5 g. (70%

yield from 3 *“Chloro-2-phenylacetophenone) of a colorless

solid, m.p. 98-99°. Two recrystallizations from ethanol-

water yielded pure m-chlorobenzil dihydrazone, m.p. 98

9 9 '0°. 3. Oxidation of m-chlorobenzil dihydrazone

To a stirred solution of 55 &• (0,25 mole) of sil

ver trifluoroacetate in l50 ml. of ethanol was added 1I4..3

g. (0.0533 mole) of m-chlorobenzil dihydrazone in 100 ml,

of ethanol and five 5 ml. additions of triethylamine over

forty-five minutes. Nitrogen evolution was continuous

for fifty minutes when 2380 ml. (100%) had been evolved.

The reaction mixture was poured into 150 ml. of concen-

1 . N. A. Khan and M. S. Newman, J. Org. Ghem. 3J’, IO63 (1952). 23. trated ammonium hydroxide solution, the resulting solution

extracted with ether, the organic layer treated in the

usual manner, and the product distilled to yield 9 g# (Q0%)

of (m-chlorophenyl)phenylacetylene, b.p. lS3-i$S° at 3 mm* Anal. Galcd. for G^^HgCl: C, 79 .1 » ^.3 ; Gl, l6 .7 .

Pound: G, 79 .3 , 7 9 .2 ; H, Gl, 16.5 , 16.5.

E, Diphenylacetylene

1. Benzil dihydrazone

Benzil ($0 g., 0.238 mole) 32 g. (1.00 mole) of

anhydrous hydrazine, 2 ml. of glacial acetic acid, and

200 ml. of ethanol were refluxed for sixteen hours to

yield 51 g. (90?^) of benzil dihydrazone, m.p. 151-1^3°

(lit.l 152-153°).

2 . Oxidation of benzil dihydrazone

To a stirred mixture of silver trifluoracetate

(80 g., 0,362 moles), 250 ml. of acetonitrile and benzil

dihydrazone (l5.0 g., O.063 moles) was added 70 ml. of

triethylamine over two and one-half hours. At the end

of the addition, 2500 ml. (89^) of nitrogen had been

evolved and after six hours 29OO ml. (103/^) had been

evolved. The reaction mixture was poured into 200 ml*

of concentrated ammonium hydroxide, the resulting solution

filtered and extracted with ether, and the organic layer

1 . W. Schlenk and E, Bergmann, Ann. L&3 , 76 (1928 ). 2l|.. treated in the usual manner to yield 9»5 g. (85^) of diphenylacetylene, m.p. 58-60° (lit.^ 6o-6l°).

P. Di(p-methoxyphenyl)acetylene

1. Preparation of anisil via anisoin

After heating 20 g. (0 ,ll;.? mole) of redistilled anisaldehyde, I4. g. of potassium cyanide, I6 g. of water, and 214. g. of ethanol on a steam bath for two hours, four additional grams of potassium cyanide were added and the heating continued for one and one-half hours.^ After ex tracting the reaction mixture with ether and removing the solvent, the product was dissolved in 100 ml, of glacial acetic acid and reacted with an excess of solid ammonium nitrate on a steam bath.3 The reaction mixture was poured

into water, the resultant solution extracted with ether, and the organic layer treated in the usual manner to yield

1I4. g. (70% from anisaldehyde) of anisil, m.p. 129° (lit.3

132-133°). 2. Oxidation of anisil dihydrazone

To a stirred mixture of 150 ml. of acetonitrile,

[j.2 g. (0.19 mole) of silver trifluoroacetate, and 11 g.

(0.037 mole) of anisil dihydrazone, m.p. 115-118° (lit,^-

1. L. I, Smith and M. M. Palkof, Organic Synthesis 22, 50(19)4.2).

2. M. Bosler, Ber. gj,, 327(1881).

3. B. Klein, J. Am. Ghem. Soc. 1^7^(19^l).

I4.. W, Schlenk and E. Bgygmann, Ann. [463, 81(1928). 25. 118°) prepared in 75^ yield from anisil, anhydrous hydra zine, glacial acetic acid and ethanol in the usual fashion, was added 50 ml. of triethylamine over one hour and forty minutes* During this time 13OO ml. (79^) of nitrogen was evolved, followed by an additional 100 ml, (6^) in the next two and one-half hours. After pouring the reaction mixture into 200 ml, of concentrated ammonium hydroxide, the resultant solution was filtered and extracted with ether and the organic layer treated in the usual manner to yield 7*5 g« (85^) of a crude product, m.p. 1^D-1^6°*

Two recrystallizations from 1:2 acetic acid-ethanol affor ded I4-.I1. g. (50^) of di (p-methoxyphenyl) acetylene, m.p, l[j.5-li|.6° (lit.l 1^2°).

1 , H. Wiechell, Ann. 2%^, 338(189^9 , Ill, Hydration of diaryl acetylenes

A, General method

About 0,2 g. of the acetylene was added to a solution of 2 ml, of concentrated sulfuric acid in 6 ml, of glacial acetic acid containing the catalyst (mercuric salts) for

that particular hydration, heated for the desired length

of time at 90“95® ^nd the hydration mixture poured onto ice.

The resulting solution was extracted with ether, the ether

layer washed with dilute sodium hydroxide solution until neutral, the solvent stripped, and the resulting material

dried in a vacuum oven for 10 minutes at room temperature.

The ketonic material was melted and thoroughly mixed, a

sample taken, and the sample diluted with alcohol to an

appropriate concentration for spectrographic measurements.

All measurements were made on a Beckman Model DU Quartz

Spectrophotometer (serial • The calculations for

(p-chlorophenyl)phenylacetylene and for (o-chlorophenyl)p-

chlorophenylacetylene were successfully made by solving a

system of three simultaneous equations such as the following:l'2

1 , N. D, Coggeshall and A, S, Glessner Jr,, Anal, Ghem, 21, $5 0 (191+9 )* 2 , R, R. Brattain, R. S, Rasmussen, and A, M, Cravath, J, Appl, Phys, 3^, 14.18(191+3)*

26, 27.

^2 “ ®X2^X+'%2°Y‘^®Z2^Z A3 - E](^3G^ i- EY3GYf- E23G2

Where A-j^, Ag, and A3 are the absorbances of the hydration mixture at wave lengths 1, 2, and 3 respectively;

E%2, E^3 are the molar extinction coefficients of pure X component at wave lengths 1, 2, and 3 respectively; Ey^,

Eyg and Ey^ are the molar extinction coefficients of pure

Y component at wave lengths 1 , 2 , and 3 respectively; E%^,

Egg, and E23 are the molar extinction coefficients of pure

Z component at wave lengths 1 , 2 , and 3 respectively; and

Gx, Oy and G% are the concentration in moles per liter of components X, Y and Z respectively. The system of equa tions was solved by the use of determinants. A sample calculation is illustrated on page

The above method of calculating the composition of the hydration mixture was found to give inaccurate results for

(o-chlorophenyl)phenylacetylene and for (m-chlorophenyl)- phenylacetylene due to the great similarity of the ultra violet absorption spectra of the two ketones produced in the hydrations (See curves on pages 3f 9" <3 7 ),

The composition of the hydration mixtures of (o-ohlorophenyl)phenylacetylene and (m-chlorophenyl)phenylacetylene was found by comparison of the ultraviolet absorption

spectra of the hydration mixtures with those of known 28. solutions of the chloro-substituted 2-phenylacetophenones*

These comparisons were expected to compare favorably at lower wave lengths, but to vary significantly at higher wave lengths due to the great absorption of any residual diaryl acetylene (see curves ^ f Q. on page )•

B, Tabulation of conditions and results

1 . (p-Ohlorophenyl)phenylacetylene 29. Table I

Hydration of 0.2 g. of (p-chlorophenyl)phenylacety-

lene at 90-9^° and the absorbances of the resulting

mixture.®

Absorbance Run 228 mu 260 mu 280 mu

1 0.631 O.6I4.9 0.105

2 0.611 0 .611-3 0.109

3^ 0.690 0.663 0.111

0.631 0.707 0.105

5° 0.665 0.701 0.120 6° 0.682 0.701 0.108 7d 0.700 0.757 0.135

8d 0.675 0.712 0.138

9" 0.6^1 0.702 0.149

The hydration time was 90 minutes for runs 1, 2,a a: minutes for run 9. b. Carried out in the presence of one milliliter of water.

c. Carried out in the presence of a catalytic quantity of mercuric sulfate.

d. Carried out in the presence of 0.5 g. of mercuric trifluoroacetate.

e. Carried out at 50-60° 30.

Table II

Molar extinction coefficients of pure (p-chlorophenyl)-

phenylacetylene, 2 (p-chlorophenyl)acetophenone, and

-chloro-2-phenylacetophenone.

^^-chloro- 2(p-chloro- 2-phenyl- phenyl)aceto- (p-chlorophenyl)- Wavelength acetophenone phenone phenylacetylene

228 mu ^.18X10^ 1 .03X10^ 8,96Xlo3

260 mu 1.[1.9X10^ S.08Xlo3 1 .7lXlo4 28l|. mu 1 .72X1q3 I.IIXIO^ 3,i}.3X10^

Table III

Results of (p-chlorophenyl)phenylacetylene hydration

calculated at wavelengths 228 mu, 260 mu and 28I4. mu.

^[|.'-chloro- ^2(p-chloro- ^(p-chloro- 2-phenylaceto- phenyl)aceto- phenyl)phenyl- Ratio Run^ phenone (C) phenone (D) acetylene P/C

3 31. 69. 0. 2.2 l|. 39 . 61. 0. 1.6 6 31).. 66. 0. 1.9 a. These runs were chosen to show the maximum variation in composition of the hydration mixture.

By averaging these results we conclude that the hydra tion of (p-chlorophenyl)phenylacetylene yields a mixture of about 35^ ^'-chloro-2-phenylacetophenone and 6^% 2(p-

chlorophenyl)acetophenone. The accuracy of the analysis

is 31.

2 « o,p•-Dichlorotolan

The hydration of 0,2 g, of (o-chlorophenyl)p- chlorophenylacetylene was effected In 6 ml. of glacial acetic acid, 2 ml. of concentrated sulfuric acid and with a catalytic quantity of mercuric sulfate at 90-95° for one hour.

Table IV

Absorbances of hydration mixtures from (o-chloro

phenyl )p-chlorophenylacetylene.

Absorbances Run 22L mu 2S0 mu 256 mu 260 mu 288 mu

1 „ 0.266 0.530 0.510 0.l^[|.2 0.072

2 0.266 0.581 0.566 0.^91 0.077

3^ 0.197 0.^38 0.1|28 0.371 0.06^ a. This hydration was done in the absence of any mercuric catalyst for 90 minutes. 32.

Table V

Molar extinction coefficients of pure (o-chlorophenyl)-

p-chi or ophenylacetylene, I4.’-chi or o-2 (o-chlorophenyl ) -

acetophenone and 2 ’-ohloro-2 (p-chlorophenyl)acetophenone

(o-chloro- li’-chloro-2- 2 '-chloro-2- phenyl )p- Wave- (o-chlorophenyl)- (p-chlorophenyl)- chlorophenyl- length acetophenone(A) acetophenone(B) acetylene

22I1. 1^.85X10^ 1.38X10^ 1 . 9 9 X 1 0 ^ 2^0 2 .02X10^ 5 .2lpaO^ 1.07X10^

2^6 2.02X10*+ 3 .81p a o 3 1.33x10^

260 1.78X10^ 2 .66X10^ l.lj.8XlO^ 288 1.09X103 1.17X103 3.S2Xlo4 33.

Table VI

Résulta of the hydration of (o-chlorophenyl)p-

chlorophenylacetylene.

^li’-chloro- ^2 ’-chloro- (o-chloro- Wave- 2 (o-chloro- 2 (p-chlorophenyl)p- length phenyl)aceto- phenyl)aceto- chlorophenyl- Ratio Run used mu phenone(A) phenone(B) acetylene A/B

1 22k-,2^6 , 68. 29. 3. 2.3 286

2b 250,260 71. 29. 2,k-

3^ 224^256 73 . 27. 2.7 b. These calculations were done assuming the absence of (o-chlorophenyl)p-chlorophenylaoetylene *

From the above results it was concluded that the hydra tion of (o-chlorophenyl)p-chlorophenylaoetylene yields a miture of about 71^ ^^-chloro-2 (o-ohlorophenyl)acetophenone and 29^ 2 •-chloro-2 (p-chlorophenyl/acetophenone. The accuracy of the analysis is t 3^o 3 » (o-Chlorophenyl)phenylacetylene

Table VII

Absorbances of a known solution of 70^ 2 (o-chloro-

phenyl)acetophenone and 30^ 2 ’-ohloro-2-phenyl-

acetophenone and of a solution of the hydration

mixture from (o-chlorophenyl) phenylacetylene in

ethanol#

Absorbance Absorbance Wavelength mu known solution hydration mixture

238 0.725 0.732

2I1.O 0.760 0.765

2l|2 0.775 0.781

0.765 0.772

2i(.6 0.735 0.749

2kQ 0.685 0.707

250 0.622 0.641

26I4. 0.067 0.092

Prom the above data it was concluded that the hydra tion of (o-ohlorophenyl)phenylacetylene yields a mixture of about 70!^ 2(o-chlorophenyl)acetophenone and 2'- chloro-2-phenylacetophenone. The accuracy of the analysis is 1 35. !(.. (m-Chlorophenyl )phenylacetylene

Table VIII

Absorbances 'of a known solution of 75^ 2(m-chloro-

phonyl)acetophenone and 2^% 3 ‘-chloro-2-phenyl-

acetophenone and of a solution of the hydration

mixture from (m-chlorophenyl)phenylacetylene in

ethanol*

Absorbance Absorbance Wavelength mu known solution hydration mixture

230 0.632 0.614.7

235 0.832 0.835 21^0 1.010 0.998

2I1.5 1.030 1.053

250 0.910 0.940

255 0.628 0.678

260 0.342 0.402

265 0.192 0.237

270 0.131 0.173

275 0.109 0.143 280 0.100 0,116

28S O.OSlv 0.097

From the data it was concluded that the hydration of

(m-chlorophenyl)phenylacetylene yields a mixture of about

75^ 2(m-chlorophenyl)acetophenone and 2^% 3 '-ohloro-2- phenylacetophenone. The accuracy of the analysis is + 36.

C, Calculation of results

The method of calculation used successfully for

(p-chlorophenyl)phenylacetylene and (o-chlorophenyl)p- chlorophenylacetylene will be illustrated by calculating the composition of the hydration mixture from (o-chloro phenyl )p-chlorophenylacetylene. The absence of any resid ual (o-chlorophenyl)p-chlorophenylacetylene will be assumed. The following system of equations can be set up*

^1 ■ % 1 Ca ^ ®B1 ^ Gg

'"a" ^ 2 "b Where A^ and Ag are the absorbances of the hydration mix

ture at wavelengths 1 and 2 respectively, and E^g are

the molar extinction coefficients of pure ^/-chloro-2(o-

chlorophenyl)acetophenone at wavelengths 1 and 2 respec

tively, Ejjj^ and Eg2 are the molar extinction coefficients

of pure 2 *-chloro-2(p-chlorophenyl)acetophenone at wave

lengths 1 and 2 respectively, C^ is the concentration of

l|.*-chloro-2(o-chlorophenyl)acetophenone in moles per liter,

and Gg is the concentration of 2 ’-chloro-2(p-chlorophenyl)-

acetophenone in moles per liter. We will analyze the mix

ture at wavelengths 22I4. mu and 2$6 mu. ^ substituting

the data from run 3 of Table IV and the necessary molar

extinction coefficients from Table V, we obtain the

equations. 37. 0.197 = Ii..85Xlo3 1 ,38X10^ Cg

0.^28 = 2,02X10^ -h 3.81(.X10^ Cg

Solve for 0^ by determinants.

0.197 1 .38X10^ 0.^28______3.8L|.X1o 3 _ - 5 . l 5X l o 3

I|..85X103 1 ,38X10*4- -2.60x108

2 .02X10*»- 3 ,81{.X103

0^ = 1.98X10-2 M./l.

Solve for 0^ by determlnantso

i|-.85X103 0.197

2 .02X10*»-_____ 0 .1|28 s -1 .90X103

^ . 8$Xlo3 1.38X10*»- -2.60x108

2 .02X10*4- 3 .81}.X1o 3

Gg = 0.73x10-2 M./l,

Total moles = 1 .98X10-2 + 0.73X10"2 « 2 .71X10-2

%k a 1.98X10-2 X 100 » 73% 2 .71X10-5

■ 0.73x10-2 X 100 = 27^ 2.71X10-5

Thus, the hydration mixture of run 3t Table IV was composed of 73^ ii.'-chloro-2(o-chlorophenyl)acetophenone and 27% 2 '-ohloro-2(p-chlorophenyl)acetophenone. Figure I 38.

U«V. Spectra of Chloro-Substituted 2-Phenylacetophenones 15.01

12.0

"q H) 8.0

4.0

1.0 220 240 260 280

150

12.0

o 9.0

3.0 210 230 250 270 290 \ (mu) Figure II 39*

U.V. Spectra of Chloro-Substituted 2-Phenylacetophenones

15.0

12.0

e 80

4.0

220 240 260 280 300

20.0

16.0

O 12.0 VI

8.0

4.0

10L_ 220 240 260 280 Figure III 1}.0,

UcV, Spectra of Chloro-Substituted Diphepylacetylenes 350

31.0

27.0

O 230-

190

15.0-

II.O

7.0 220 240 260 280 300 A (m/l)

31.0

27C

O lu 190

15.0

II.O

70 210 230250 270 290 310 A(rr)n) Discussion of results

I. Methods of synthesis

A, Synthesis of chloro-substltuted 2-phenyl-

acetophenones

The chloro-substltuted 2-phenylacetophenones have all been previously preparedl*2 in ^ 2 - 8 0 ^ yields (calculated on benzamlde) by refluxing a three to four molar quantity of the appropriate benzyl Grignard reagent with the approp riate benzamlde In ether solution for forty to seventy hours. In the present work yields (calculated

RCONH21- 3R 'GHgMgBr RG(0MgBr)(N[MgBr]2)CH2R' RCOGHgR' on benzcnltrlle) of the same chloro-substltuted 2-phenylacetophenones were obtained by refluxing a one to 1.2$ molar quantity of the appropriate benzyl Grignard reagent with the appropriate benzonltrlle In ether for six hours*

The nltrlle-Grlgnard method has the advantages of requiring a smaller amount of benzyl Grignard reagent per mole of ketone produced and of requiring much less reaction time,

RGN + R'CH2MgBr — > RG(MgBr)0H2R ‘ :> RGOGH2R'

1 . S. S. Jenkins, J . Am. Ghem, Soc. 703, 2096(1 933 )» $6, 682(193^). 2 . S. 8. Jenkins and E, M. Richardson, J. Am. Ghem. Soc. 1618, 3871^.(1933)♦

ij.1. IV2 .

Table IX

Yields and physical constants of 2-phenylaceto-

phenones

Benzonitrile- Benzamide- Grignard % Grignard M.p, of Ketone Yield % Yield pure ketone o-ClC6H^CH2C0C&H^Cl.■P 7$ 80 107. k-108.1^.0 o-ClC^H^j^COCHgC^Hi^Cl-*P 72 72 63.0-62.0° p-ClG6H^C0GH2C6H% a 77 106.0-107.0° p-GlG6H^GH2G0G6H2 70 70 137.6-138.2° o-GlGaH^GEgGOGGH^ 5$ 73 6 9.0-70.2° o - G 1 G^H[^G0GH2G^H^ 71 71 (iLjil--114.6° at 1 imn)° m-GlG6H^GH2G0G6H2 il-7^ k2 ^1.8-42.8° m-GlG/H. GOGHpG/Hj. 76 62 60.14.-61.6°

a. This ketone was prepared by a Priedel-Crafts reaction of phenylacetyl chloride upon chlorobenzene. b. Upon distillation a narrow fraction was taken to insure purity of the sample. The total yield is not known. c. Boiling point lt-3 . B. Synthesis of diaryl acetylenes

1, Elimination method

In the preparation of (o-chlorophenyl) p-chlorophenylacetylene and (p-chlorophenyl)phenylacetylene the general method of the treatment of the appropriate 2- phenylacetophenone with phosphorus pentachloride followed by basic elimination of two molecules of hydrogen chloride was successful, p-ClG6H^C0CH2C6H^Gl-o ) p-ClC^Hi^CGlgCHgC^Hl^Cl-o ^

p-GlG^H^G^GG^H^Cl—o

p-GlG^Hi^GGGRgG^H^ ^ p-GlC^Hij^GGlgCHgG^H^

p-GlG^H^GSGG^H^

However, an attempt to prepare (o-chlorophenyl) phenyl-

acetylene by treatment of 2 ’-chloro-2-phenylacetophenone

with phosphorus pentachloride followed by the basic elim

ination of hydrogen chloride yielded only a liquid mixture

which was thought to consist of the desired product and

cis l-chloro-l(o-chlorophenyl)2-phenylethylene. This

mixture could not be separated by fractional distillation

or chromatography*

2 . Oxidative method

Diaryl or dialkyl acetylenes have been oxidatively

prepared by refluxing oC-dihydrazones with mercuric oxide 44. in benzene or ethanol solution for long periods of time in only fair yields.1 *2,3,4 In addition to giving only

RC(NNH2)C(NNH2)R' T 2HgO ^CSCR' t 2Eg + 2N2 f 2H2O fair yields, the disadvantages of this reaction are the long reaction time at reflux temperatures which are nec essary and the heterogeneous nature of the oxidizing agent. It was thought that these disadvantages could be overcome if a homogeneous oxidizing agent could be found.

In the past the Wolff rearrangement of oi-diazo ketones using methanol and silver oxide had also proved to be somewhat erratic,^ however, the rearrangement proceeded very smoothly when a solution of silver benzoate in triethyl amine was used as the catalyst.^*? In this present work it was found that silver trifluoroacetate in acetonitrile or ethanol was an excellent oxidizing agent for

c^rdihydrazones when a stoichiometric quantity of tri

ll A. T. Blomquist, R. E. Burg, and A. C, Suosy, J. Am. Chem. Soc. %4,, 3&34, 3636(1952).

2. T. Gurtius, Bar. 22, 216KI889).

3 . T. Gurtius, J. Prakt. Chem. ^j., 171 (1891)*

I4.. W, Schenk and E. Bergmann, Ann. 14.63, 76(1928).

5 . Organic Reactions, John Wiley & Sons, Inc., New York, K. Y., 19^2 , p. 52.

6. M. s. Newman and M. Wolf, J. Am, Chem, Soc, 74 ,3225(1952 )

7. M. S. Newman and P.- P. Beal III, J, Am. Chem. Soc# 72, 5163(1950). ethylamlne waa present to take up the liberated trifluoro- acetic acid* The stoichiometry of the reaction is illus trated below.

NNHp WNHp R Ô — R« -t l).GF^GOOAg + »

RGSGR' -f- liAg f 2N2 f ^^PjGOOH'fGgH^ijN

The progress of the reaction was followed gaaometrically and in all examples an approximately quantitative amount of nitrogen was evolved* A yield of 85^ of once recrystal lized diphenylacetylene was obtained using the silver trifluoroacetate-triethylamine method in contrast to a 7^% yield from the mercuric oxide-benzene method*

The best procedure found was to add an ethanolic solu tion of the dihydrazone to a stirred solution of silver trifluoroacetate in ethanol and to periodically add small portions of triethylamine. The nitrogen evolution was immediate and the reaction warmed slightly* The reaction was stirred until the theoretical quantity of nitrogen was evolved* lj-6.

Table X

Reaction conditions, yields and physical constants

of diaryl acetylenes prepared by the silver ion-

triethylamine method,^

Reaction time Acetylene (hrs) evolved % ïield M.p, or b.p« g ^h ^g m c c ^h ^ 2.S 8^ 58-60O 6,0

- 1.5 85 1^D-1^6° OGH^**p i|.,0 11 o-GlG^Hj^OsGG^H^ ll-.O 100 32a 1^5-1^7°at 3mm. m-GlG^H^GSGG^H^ 0.8 100 80 153-I55°at 3mm. a. The total yield is not known. The 32^ is the center cut used as an analytical sample,

b. All the oxidations were done at room temperatureo

o-Ghlorobenzil and m-chlorobenzil, intermediates in the preparation of o-chlorobenzildihydrazone and m-chlorobenzil-

dihydrazone, were prepared in good yield from 2 (o-chloro-

phenyl)acetophenone and 3 ’-chloro-E-phenylacetophenone,

respectively, by heating to 130-1)4.0° with selenium dioxide

and acetic anhydride for four hoursWhen selenium

dioxide was unavailable, identical yields of the diketones

1 , H, H, Hatt, A, Pilgrim, and W, J. Hurran, J, Ghem, Soc. 1936. 93. 1^7. were obtained by reacting the appropriate 2-phenylacetophenones with potassium permanganate^ in pyridine-water solution, at room temperature, while controlling the pH of the solution near 7 with periodic additions of carbon dioxide. At pH 7 stearolic acid has been^ oxidized to

9»10-diketo-stearic acid with aqueous potassium perman ganate in 95^ yield; whereas the 9*10-&lkGto-stearic acid was cleaved at a pH of 12 or at a pH of 1 , For this reason it was necessary to control the pH of the oxida tion medium around seven.

3* Unsuccessful attempts to prepare diaryl

acetylenes*

An attempt to prepare (o-chlorophenyl)p-chloro-

phenylacetylene by a method^ known to give good yields

for diphenylacetylene was unsuccessful due to the great

ease of dehydration of the Reformatsky product from 2,lj.*-

dichlorobenzophenone, and ethyl bromoacetate. The yield

of this reaction was too small to continue the synthetic

sequence.

1.1 . M. Gombergüomoerg and F. J. Van Natta, J. Am. Chem. Soc. 51, 2238(1929). 2. N. A. Khan and M. S. Newman, J. Org. Chem. 17, 1063(1952)0

3. M« S. Newman and A. Kutner, J. Am, Chem. Soc, 73, 4199(1951). 1,.8 .

OH o-ClC5H|,COC5HhCl-p f. BrCHgCOOCgH^ Y- Zn_^ o-ClCaHrCCHgCOOCgHd OtH^Cl-p

An attempt to prepare (o-chlorophenyl)phenylacetylene by the synthetic sequence^ of Chart I was a failure, since the conditions of the final reaction in the sequence removed the aromatic chlorine atom. Aromatic halogen atoms are removed by potassium amide in liquid ammonia.The

Chart I

Unsuccessful method of synthesis of (o-chlorophenyl)

phenylacetylene o-ClC^H^COCl o-ClC^H^COC^H^ ^ o-C1C^H,^C(OH)(CH3 )C5H^ Î C - > o-C1C^H^(C^H^)C=CH2 o-OlC^H^( C^H^ ) C=CHBr -H^^o-C1C^H^CSCC£,H^ aromatic bromine atom of l-p-bromophenyl-l-phenyl-2- bromoethylene is removed^ by treatment with potassium amide in liquid ammonia ; however, this rearrangement can

1. G. H. Coleman, W. H. Holst, and R. D. Maxwell, J. Am. Chem. Soc. 2310(1936).

2. P. W. Bergstrom and C. H. Horning, J, Org. Chem. 11, 33^(1946). 3. R. E. Wright and P. W. Bergstrom, J. Org. Chem. 3^ 179(1936).

Ij.. A. A. Bothner-By, J. Am. Chem. Soc. JJ_, 3293(195^) p-BrC^H^^C&H^lCsOHBr -f KNHg ^ acid soluble products

> p-Br06Hi^0=0C6H5

be successfully performed by using potassium t-butoxide

in t-butyl alcoholo This last paper was published after

our work was performed*

An attempt to prepare (o-ohloPDphenyljphenylacetylene

by the synthetic sequence of Chart II was unsuccessful*

The Perkin reaction^ was carried out in 9^^ yield to give

the desired product, which, however, could not be brom-

inated either as the acid in chloroform solution or in

glacial acetic acid solution or as the sodium salt in water.^

Chart II

o-ClC^H|^CHO + C^H^CHgCOONa iCHgCO^pO^ o-ClC^H^CH=C(C^H^)COOH

— o-ClC£,H|^CHBrCBr(C5H^)C00H > o-ClC^Hj^CH=C( Br )C^H^

■> o-ClC^H^C»CC^H^

1 . Organic Reactions, Vol. I, John Wiley & Sons, Inc*, New York, N. Y., I9I4.2, p. 252.

2* R. Müller, Ber. 2^ 659» 66I|.(l893)« II. Analytical method

Three component systems have often been analyzed by 1 P ultraviolet absorption spectroscopy. * The accuracy of this method is very good if the three components have radically different ultraviolet absorption spectra.

An accuracy of 1 0.3% was claimed^ in the analysis of naphthalene, c^-methylnaphthalene, and f-methylnaph-

thalenso However, if two of the three components have

nearly identical ultraviolet absorption spectra and the

spectra do not cross in any place, then the accuracy of

the method is not as good*

The absorbance, A, of a solution is the logarithm

of the ratio of the incident light, 1q , to the trans

mitted light, 1, The Beer-Lambert Law^ states that the

absorbance of a solution at a given wavelength is depen

dent on the molar extinction coefficient,6 , of the

solute, the concentration, C, of the solute in moles per

liter and the length, 1, of the cell in centimeters*

A a logio ^ =6 01

1. N. D, Coggeshall and A. 3. Glessner, Jr., Anal* Chem. 21, 550(1949). 2. R. R. Brattain, R. S. Rasmussen, and A, M. Gravath, J, Appl. Phys. llj^ 418(1943)*

3 . V/. R. Brode, Chemical Spectroscopy, John Wiley & Sons, Inc., New York, N. Y., 1939; P* 152*

50. 5 1 . Since the absorbance of a mixture. Am, is equal to the sum of the absorbances of the individual components and since the cell length is one centimeter, we can write the following equation

Am *• A^ 4" Ag A^ “ ^1^1 ^2^2 ^3^3

Thus, to analyze a mixture of three components, the absorbance of the mixture must be measured at three wave lengths*

The only data necessary for an analysis is the absor bance of the unknown mixture at the appropriate wave lengths (preferably at those wavelengths where the absorptions of the components differ most) and the molar extinction coefficients of each of the pure components at each of the wavelengths chosen for analysis* The data is then substituted into a system of equations such as that illustrated on page and the equations solved simultaneously for the œoncentration (in moles per liter) of each of the three components* Since the molar extinc tion coefficients of the pure components are necessary, great care was taken in the purification of the materials and yields were sacrificed in favor of purity*

The two ketones resulting from the hydration of (p« chlorophenyl)phenylacetylene, ^i-chloro-2-phenylacetophenone and 2 (p-chlorophenyl)acetophenone, have ultraviolet absorption spectra which differ greatly and which cross at 52.

21^.6 mu (see curves on page ), In this hydration the amount of residual (pjchlorophenyl )phenylacetylene is very small and therefore offers no complications. These ketones are ideal for treatment by this method and the accuracy in this analysis should be good*

The two ketones resulting from the hydration of (o-

chloro phenyl ) p- chlorophenylacetylene, l<. ’ -ohloro-2 ( o-

chlorophenyl)acetophenone and 2 ’-chloro-2 (p-chlorophenyl)- acetophenone, have ultraviolet spectra which differ greatly

and which cross at 235 mu (see curves on page 39)» In

this hydration the amount of residual acetylene is small

and offers no complications. These curves are also ideal

for treatment by the above method and the accuracy in the

analysis should be good.

However, in the analysis of the hydration mixture from

(o-chlorophenyl)phenylacetylene, we must analyze for two

ketones which have very similar ultraviolet absorption

spectra. See the curves for 2 (o-chlorophenyl)acetophenone

and 2 ’-chloro-2-phenyl-acetophenone on page » This is

not an ideal case for the use of the above method and very

erratic results were obtained. Accordingly the mixture

was analyzed by comparison of the absorbances of the hydra

tion mixture with the absorbances of known mixtures of the

two ketones* This method has one disadvantage in that any

residual (o-chlorophenyl)phenylacetylene in the hydration 53. mixture will increase the absorbances of the hydration mixture due to its great absorption, especially at longer wavelengths (see curve on page yo). An attempt to overcome this disadvantage was made by carrying out the hydration for longer periods of time to insure com pleteness of reaction. However, our data shows that some

(o-chlorophenyl)phenylacetylene still remained in the hydration mixture. Hence, the absorbances of the hydra

tion mixture agree well with those of the known mixture

at lower wavelengths, but deviate appreciably at higher wavelengths. The accuracy of this latter method is not as good as that of the former method, but still should give

an accuracy of ±

The same situation existed in the analysis of the hydra

tion mixture from (m-chlorophenyl)phenylacetylene as existed

in the case of (o-chlorophenyl)phenylacetylene. The two

ketones have very similar ultraviolet absorption spectra

(see curves on page 3?). The composition of the hydra

tion mixture from (m-chlorophenyl)phenylacetylene was

determined by comparison of the absorbances of the hydra

tion mixture with those of known mixtures of 2 (m-chloro

phenyl ) acetophenone and 3 •“chloro-2-phenyl-acetophenone.

The absorbances of the hydration mixture deviate from those

of the synthetic mixture due to small quantities of resid- aal (m~chlorophenyl)phenylacetylene. This deviation

Is most pronounced at longer wavelengths, where the residual (m-chlorophenyl)phenylacetylene absorbs more strongly* III. Hydration of diaryl acetylenes

Before the discussion of this work is attempted it is necessary that we briefly review what is known concenning the hydration of disubstituted acetylenes. The mechanism of the hydration of disubstituted acetylenes has not been definitely established. A general mechanism for the acid hydration, catalyzed by ion, of all acetylenic bonds has been proposed^ in which the initial step is the addi tion of the mercuric salt to the triple bond followed by successive reactions with water and acid to give the enol form of the final ketone. "A” represents the acid radi cal contained in the mercuric salt.

RG2GR' + HgAg »RG(A)*G(HgA)R' RG(OH) = G(HgA)R»

RG(OH)»GHR'^=^ RGOGHgR'

The authors stated that the initial addition product is extremely reactive and easily decomposed*

A kinetic study^ has been made of the mercuric acetate catalyzed addition of acetic acid to 3-hexyne to yield 3- acetoxy-3-hexene. The nature of the intermediate complex

1. G. P. Hennion, R. R. Vogt, and J. A. Nieuwland, J. Org. Ghem. 1, 159(1936).

2. H, Lemaire and H. J. Lucas, J. Am. Ohem. Soc. 77* 939(1952).

55. 56. ion was studied by the indicator method^ and the following mechanism was proposed.

GgH^GzCOgH^ + H'^-h Hg(0A c )2 ( HgOAc ) + AcOH

§2H5G=G(HgOAc)G2H^] + AcOH Siov^ G2H^GH::G( GAc )G2H^ ± HgOAc'^

The authors stated that the acetoxymercury(II)-3-hexynium ion would be stabilized by resonance with three resonance forms. yHgpAc ^HgOAc ■^'HgOAc G2H^C=G -G2H^t— > G2H^G=CG2H ^ W

The formation of coordination complexes between a metal

ion and an acetylene, an olefin, or even an aromatic hydro

carbon has been well established, A very close analogy to

the acetylene-mercuric ion canplex is the cyclohexene- mercuric ion complex^ which is stabilized by resonance of

the same type as that shown for the acetoxymercury(II)-3-

hexynium ion. The silver ion will form three types of

complexes with olefins;^ (1) one silver ion will combine

with one olefin molecule, (2) one silver ion will combine

with two olefin molecules, and (3) two silver ions will

combine with one olefin molecule. All of these different

silver olefin complexes are stabilized by resonance. The

1 , H. Lemaire and H. J. Lucas, J. Am, Ghem. Soc, 73, 5198(1951)0

2e H. J, Lucas, P. R. Hepner, S, Winstein, J, Am. Ghem, Soc. 61^ 3102(1939).

3, S, Winstein and H, J. Lucas, J. Am. Ghem. Soc, 60, 836(1938), 57. silver Ion complexes of aromatic hydrocarbons^ are said to be simply a TT-complex in which the Ag ion imbeds it self in the TT-electron cloud of the aromatic hydrocarbon*

These TT-complexea are very similar to the TT-complexes o between aromatic hydrocarbons and iodine or bromine o'”

Recently, it has boen demonstrated that the bromination of mesitylene in wet carbon tetrachloride at 25® in the dark actually involves an attack by a hydronium ion on a

1:1 mesitylene? bromine complex in the rate determining step.3

f ( GH3 ) 3G5H3* Brg

HgO t HBr t Br“

(GH3)3G6H3Br2fH30^ _âl22^ (GH3 )3C6H3Br'^ + HBr + HgO

(GH3 )3G6H3Br ,.f^,3t ^ (GH3 )3C6H2 Br f H"^

Prom the above brief description we can see that many varieties of coordination or addition complexes do exist

and that they do play a very real part in the course of many reactions*

1 . L, J. Andrews, Ghem. Revs. 5L, 713(195^)*

2 , R. M. Keefer and L. J. Andrews, J. Am. Ghem. Soc* 77* 2164X 1955). 3* R. M. Keefer, J. H. ELake, III, and L. J. Andrews, J. Am. Ghem. Soc. 3062(1954.). 58.

Recently, evidence has been published that not only do metal ions and halogen molecules complex with the TT- electrons of olefins, acetylenes, and aromatic hydrocarbons, but that protons can also exhibit this phenomena. It is proposed^ that in the acid hydration of isobutylene the first step is a facile proton transfer from hydronium ion to olefin to form the conjugate acid of the olefin. Since it has been shown that this conjugate acid cannot be a carbonium ion, the existence of a TT-complex is implied#

This TT-complex must be a very unstable reaction inter mediate and the evidence favors the following mechanistic path. PH: R.D. CHoC- ■?CHo

fast HgO^ ' PH, ÇH3 CHoC — ;cH' ;gh3 T HgO ---- ÜHg 6h

The rate determining step involves the transfer of the

hydrogen from its position in the TT-complex to an adja

cent carbon atom to form a conventional C-H bond. The

1 . E. L, Purlee and R. W. Taft, Jr., J, Am. Chem. Soc, Z8, 5807(1956), 29. authors emphasized^*^ that this TT-complex is structurally distinct from the bridged protonium ion^»^(X) (or bridged mercurinium ion) in which all bonds about the two carbon atoms are directed bonds which give rise to a non-coplanar structure© .

k y t r y " :

Y, TT’-complex X, bridged protonium ion (directed bonds of (bonds of structure structure coplanar) non-coplanar)

However, the bonding of the 7T-complex Involves overlap of the orbital of hydrogen with the TF-orbital of the C-C bond. Except for the embedded proton, the structure is that of an olefin with its trigonal coplanar structure about both C atoms. The bonding of the proton to the

7T-orbital is apparently quite weak*

Prom this mass of information on the ability of systems with TT-electrons to complex with a positive species of many varieties, it appears that the first step in the

hydration mechanism of acetylenes must surely be a complex

forming step. Whether this complex is one of a mercuric

1 , E, L, Purlee and R, W, Taft, Jr., J, Am, Ghem, Soc, 5811(1956),

2# L, G, Oannell and R, W. Taft, Jr., J, Am. Chem. Soc* Zâ, 5812(1956).

3. S, Winstein and H. J. Lucas, J, Am, Ghem. Soc, 60, 836(1938).

I4.. D. J. Cram, J. Am, Ghem, Soc, Jkf 2137(1952). 6o. ion and an acetylene molecule or one of a proton and an acetylene molecule cannot be of too great significance since acetylenes can be hydrated in the absence of mercuric salt3»^ This has been demonstrated in this work also (see page 2?).

In this present work no rate studies were made and therefore we are not in a position to comment on the mech anism of hydration of disubstituted acetylenes. In this work the product proportions of the two isomeric ketones resulting from the hydration of the unsyrametrical acetylene were studied in an effort to study the directive effects of substituent groups on the hydration and, furthermore, to see if these directive effects were additive. There are four directive effects which may bear an influence on the product proportions of the hydration. They are the inductive effect on the ground state, the resonance effect on the ground state, the resonance stabilization of the transition state, and the field effect on the ground state#

The inductive effect on the ground state of the mole

cule will be considered to operate in the following manner.

The chlorine atom pulls sigma electrons toward it. This

1, A, Behai, Ann, chim, 3^, 270(1888), 61. pull diminishes as the distance between the chlorine atom and the reaction site increases. Thus the sigma bonds will be polarized in the indicated direction. This shift in the location of the sigma electrons of the triple bond will have an effect on the location of the TT-electrons of the triple bond, which will be shifted in the same direction*

Sigma bond shift jT-bond shift

^ A

Since the induction by an ortho chlorine atom works through a shorter distance than the induction by a meta chlorine atom, the inductive effect of the ortho chlorine atom will be greater than that of the meta chlorine atom. Similar- ily, the inductive effect of a meta chlorine atom will be greater than that of a para chlorine atom. In considering the inductive effect we will assume that the positively charged species^ attack at the point of highest electron density of the TT-electrons of the triple bond and that this initial attack will determine the final product. If the point of highest electron density of the IT-cloud of

1. This positively charged species could be a solvated mercuric ion, a solvated mercuric monoacetate ion, or a solvated proton. 62. the triple bond is determined only by the inductive effect of the chlorine atom, then the protonated attacking species will be directed to the carbon nearest the chlorine atom and the carbonyl function will appear on the carbon furthest removed from the chlorine atom, e.g. i— > C^H^CsCG^H^j^Gl-p --- > G^H^GOGHgG^Hlj^Gl-p

The resonance effect on the ground state of the mole cule will be considered to operate in the following manner#

A chlorine atom in an ortho or para position can resonate with the triple bond to give structures such as A and G,

Resonance of a chlorine atom in a meta position will be

considered to be inoperative. A phenyl group can resonate with the triple bond to give structures such as B and D.

ci-0 hC=c-<0 ) 4 - ^ I A

C/ X- + ^ y H = c = o *

The resonance contributions of structures A and C will be

considered to be more important than the resonance contri

butions of structures B and D. In considering the reson

ance effect we will assume that the positively charged 63. species attacks at the point of highest electron density of the TT-cloud of the triple bond and that this initial attack will determine the final product. If the point of highest electron density of the TT-cloud of the triple bond is determined only by the resonance effect of the chlorine atom on the ground state, then the protonated attacking species will be directed to the carbon furthest removed from the chlorine atom and the carbonyl function will appear on the carbon atom nearest the chlorine atom, e.go 4--> o-01C6H^C=CC&Hg ---- > o-ClC^Hii^COCHgC^H^

The resonance stabilization of the transition state

of the molecule will be considered to operate in the

following manner. The diaryl acetylene reacts with the

"positively charged species" to form the two possible

transition states. For this discussion we will consider

the positively charged species to be a proton#

^ -

Both of the transition states are capable of being stab

ilized by resonance with chlorine atoms in the ortho and

para positions and by resonance with the phenyl rings

themselves. Resonance stabilization by resonance with 6i|.. meta chlorine atoms is considered to be inoperative.

( y j - Q . , c= c

Transition state A will be slightly more stable than

transition state B due to resonance stabilization. In general the transition state with the plus charge on the

carbon atom adjacent to the phenyl group will be slightly more stable than the transition state with the plus charge

on the carbon atom adjacent to the chlorophenyl group#

One of the rules of the resonance theory states that the more symmetrical the resonance structures of a species

are, the more energy that resonance structure will con

tribute to the stability of the species. Therefore,

transition state G will be more stable than transition

state D and transition state E will be more stable than

transition state P.

O-'V'-O"

“O— cr Cl If we consider that the final product of the hydration is determined only by the stability of the transition states and that the more stable transition state will produce the product, then the protonated attacking species will be directed to the carbon nearest the chlorine atom and the carbonyl function will always appear on the carbon atom furthest removed from the chlorine atom, e,g* p-ClC^H^GHCC^H^ ------> p-ClG^H^GHgCOC^H^

The field effect on the ground state of the molecule ] p will be considered to operate in the following manner* *

The electron density of the TT-cloud around the triple bond of (o-chlorophenyl)phenylacetylene is greater than the electron density of the tt-cloud around the triple bond of

diphenylacetylene due to the proximity of the electrons

of the o-chlorine atom. However, the electron cloud of

the chlorine atom will repulse the electron cloud of the

triple bond and set up a relative polarity of tho triple

bond as indicated belowo <—H G6H2G=CG&H^Gl-o

The influence of the field effect on the polarization of

the triple bond will diminish rapidly as we go from an

1* J. D. Roberts and R. A. Garboni, J. Am. Chem. Soc# 21, 25>4 (1955). 2* J. D. Roberts and W. T, Moreland, J. Am. Chem. Soc* z i , 2 1 6 7 (1953)0 66* ortho chlorine atom to a meta chlorine atom to a para chlorine atom. In considering the field effect we will assume that the positively charged species attacks at the point of highest electron density of the TT-electrons of the triple bond and that this initial attack will deter mine the final product. If the point of highest electron density of the TT-electrons of the triple bond is deter mined only by the field effect of the chlorine atom, then

the protonated attacking species will be directed to the

carbon furthest removed from the chlorine atom and the

carbonyl function will appear on the carbon atom nearest

the chlorine atom, e.g.

C^H^G3gC^H)^C1-o ---- ? G^H^CHgCOG^H^Gl-o

Table XI is a comparison of the actual product pro

portions from the hydration of the four diaryl acetylenes

and the product which is predicted from the above consid

erations of the four directive effects* From the table it

can be seen that in all four hydrations the correct major

product is predicted by the inductive effect on the ground

state of the molecule. Tho use of the resonance stabili

zation of the transition state in predicting the major

product of the hydrations also gives the correct isomer*

The use of the resonance effect on the ground state or the

field effect on the ground state in predicting the major 67.

Table XI

Comparison of the found direction of hydration of

diaryl acetylenes with the direction of hydration

predicted from the directive effects.**^

o-C1C^H[j^C5CC£jH^ o-GlC^Hi^GHgCOG^H^ o-GlG^jHi^COCHgC^H^ Predicted 1. X 1 . 2o 2 . X

% Pound 10% 309&

m-GlC6H^G=GG6H2 m-GlG^H^CHgCOG^H^ m-GlC^H^GOCHgC^H^ Predicted 1. X 1 . 2. , 2 .

% Pound 1S% 25^

a. The directive effects tabulated are as follows: 1. The Inductive effect on the ground state, 2, The resonance effect on the ground state, 3 * The resonance stabilization of the transition state, and The field effect on the ground state, b. An X indicates that the effect would predict the above isomer from the hydration of the diaryl acetylene,

c. Both of these directive effects will exart only a small influence on the direction of hydration.

d« Isomer predicted due to symmetry of resonance structures. 68. Table XI (cont. )

p-ClC^H^CHgCOG^H^ p-OlC^H^COCHgC^E^ Predicted 1. X 1. 2 o 2. X X x°

% Pound 35^

p-ClC6H^^G=CC6H^^Gl-o p-GlG^H^GEgGOG^H^Gl-o p-GlG^^H^GOGHgG^H^Gl-o

Predicted 1, 1. X 2 o

. X I fo Pound 11% 69. product of the hydrations never gives the correct isomer; although these effects undoubtedly account for the minor product in each case. Therefore, it seems that all four directive effects are operative and that the two major effects on the direction of hydration are the inductive effect on the ground state of the molecule and the reson ance stabilization of the transition state of the molecule.

If a rate of hydration of one is assumed for the rate of the reaction in which the phenyl group directs the carbonyl group to the carbon nearest the phenyl group, then the relative rate of hydration for the reaction where an o-chlorophenyl group directs the carbonyl group to the

carbon nearest the o-chlorophenyl group can be calculated

from the product proportions resulting from the hydration of (o-chlorophenyl)phenylacetylene, Similarily, the

relative rates of hydration for the reactions where a m-

chlorophenyl group or a p-chlorophenyl group directs the

carbonyl group to the carbon nearest to itself can be

calculated from the product proportions resulting from

the hydration of (m-chlorophenyl)phenylacetylene and (p-

chlorophenyl)phenylacetylene, respectively. If the

logarithm of these relative rates are plotted against the

logarithm of the ratio of the ionization constant of the

appropriate chloro-substituted phenylpropiolic acid to 70. the ionization constant of phenylpropiolic acid,^ a straight line plot is not obtained.

The hydration of (o-chlorophenyl)p-chlorophenylacetylene yielded 71^ i^.*-chloro-2(o-chlorophenyl)acetophenone and 29^ 2 '-chloro-2(p-chlorophenyl)acotophenone. If we assume that the directive effects are additive, v/e can calculate a predicted value for the product proportions resulting from the hydration of (o-chlorophenyl)p- chlorophenylacetylene by using the actual values of the product proportions resulting from the hydration of (o- chlorophenyl)phenylacetylene and (p-chlorophenyl)phenylacetylene. Those values of the percentages will be used which give a calculated value for the product proportions of (o-chlorophenyl)p-chlorophenylacetylene which best agrees with the actual value. In the hydration of (o- chlorophenyl)phenylacetylene the carbonyl group was directed away from the chlorine containing ring 75^ of the time. In the hydration of (p-chlorophenyl)phenylacetylene the carbonyl group was directed away from the

chlorine containing ring of the time. In the hydra

tion of (o-chlorophenyl)p-chlorophenylacetylene, if we

1, M. S, Newman and S, H, Merrill, J, Am, ^hem. Soc* m 5522(1952). 71. let X equal the per cent isomer with the carbonyl group directed away from the ortho-chlorine atom, we can set up the equation;

75 _ X _ 62 100-X

Solving this equation for X, we obtain X equal to 55^.

Therefore, the calculated value for the product proportions

of the two ketones from the hydration of (o-chlorophenyl)-

p-chlorophonylacetyleno is 55^ ^*-ohloro-2(o-chlorophenyl)-

acetophenone and lt-5^ 2 ’-chloro-2(p-chlorophenyl)acetophen-

one. It can be seen that the actual and calculated values

for the product proportions do not agree, even if those

percentages are used which give the best agreement to tho

actual value. It is concluded that there is no inate

additive directive effect of an ortho or para chlorine

atom which carries over from diaryl acetylene to diaryl

acetylene and hence we must consider the hydration of

each diaryl acetylene as a separate case* Summary

The preparation of (o-chlorophenyl)phenylacetyleno,

(m-chlorophenyl)phenylacetylene, (p-chlorophenyl)phenylacetylene, and (o-chlorophenyl)p-chlorophenylac©tylene has been described, (o-Chlorophenyl)phenylacetylene and

(m-chlorophenyl)phenylacetylene were prepared by a new method which involved oxidizing the dihydrazones of o- chlorobenzil and m-chlorobenzil with silver trifluoroacetate and triethylamine in acetonitrile or ethanol solution. Both (p-chlorophenyl)phenylacetylene and (o- chlorophenyl)p-chlorophenylacetylene were prepared by treating the appropriate chloro-substituted 2-phenylacetophenone with phosphorus pentachloride followed by basic elimination of two molecules of hydrogen chloride»

The eight chloro-substituted 2-phenylacetophenones, which result from the hydration of the fopr diaryl acetylenes, were prepared by reacting benzyl Grignard reagents with benzonitrileso

The four diaryl acetylenes were hydrated by heating in a sulfuric acid-acetic acid solution both in the presence of and in the absence of catalytic amounts of mercuric salts. The ratios of the two Isomeric chloro-

substituted 2-phenylacetophenones, resulting from the

hydration of each of the four diaryl acetylenes, were

72. 73. determined by means of ultraviolet absorption spectros copy. The hydration of the acetylenes gave the following results*

o-ClG^H^C=GC^H^_^ o-G 1C^H^CH2C0C5H^ o-ClG^Hi^COGH2C5li5 70^ 30^ m-ClC£jH^G=GC^H^—^ m-ClC^H^GH2G0C^H^ + m-GlC^Hi^COGHgG^H^

7 S # 2 2 # p-GlG^H|^C=GG^H^— » p-GlG^H^GHgCOG^H^ f p-GlC^^H^COCHgC^H^ 6 2 # 3S# o -g i g ^ h ^^g Hg g ^h ^ g i -p >

o-ClG^Hi^CHgGOC^^Hj^GL-p + o-ClC^Hi^GOCHgG^H^Cl-p 71# 29#

The direction of hydration of the dlaryl acetylenes has been discussed with respect to four directive effects*

The use of the inductive effect on the ground state of the molecule and the resonance stabilization of the trans ition state of the molecule in predicting the major product of the hydration always gave the correct isoiaer. There was no inate additive directive effect of the o-chloro phenyl or p-ohlorophenyl groups which could be carried

over from diaryl acetylene to diaryl acetylene and, hence,

the direction of hydration of each diaryl acetylene must

be considered as a separate case* Autobiography

I, Donald Eugene Reid, was born at Brookville,

Pennsylvania, July 18, 1930, and received my secondary education in the public schools of that town* In 19^1-8 I enrolled at Franklin and Marshall College at Lancaster,

Pennsylvania, and received the degree Bachelor of Science from that institution in 1952* I was married to Dolores

A, Creamer in 1952, and a daughter, Laura Leo, was born in 1955* In 1952 I entered the Graduate School of The

Ohio State University, While completing the requirements for the degree Doctor of Philosophy, I held the following positions: Teaching Assistant in the Department of

Chemistry 1952-195^ and spring and fall quarters of 1958,

Research Fellow in The Ohio State University Research

Foundation on project RF^#9 sponsored by the Office of

Ordnance Research, 1954^1955* Research Fellow of the

Eastman Kodak Company, 1955-1958» end Research Fellow in

the Department of Chemistry for the summer quarter, 19 5 8 ,

and the winter quarter, 1957*

7L*