The Preparation and Hydration Op Unsymmetrical

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 By 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-chlorophenyl)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)phenylacetylene at 90-95° and the absorbances of the resulting mixture .......................... 29 II Molar extinction coefficients of pure (p-chlorophenyl)phenylacetylene, 2(p-chlorophenyl)acetophenone, 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)phenylacetylene 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)phenylacetylene In ethanol ............................ 35 IX Yields and physical constants of 2-phenylacetophenones . .....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

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