[CONTRIBUTIOT FROM
THE
RESEARCH LABORATORIES OF THE SPRACUE ELECTRIC Co.]
The Polymerization of o-p-Toluylbenzoic Acid BY
SIDNEY D.
ROSS 4 N D
MEYERSCHWARZ
RECEIVED DECEMBER 28, 1954 I n both polyphosphoric acid and perfluorobutyric anhydride, o-p-toluylbenzoic acid reacts to give low molecular weight, red polymers. The structure XI11 is proposed for the polymer, and its formation is rationalized as involving the additioii of a carbonium ion V I 1 t o a quinoid form T'III.
I t has been shown' that, in sulfuric acid solution, o-berij.oylhenzoic acid ionizes according t o the equations
acetic anhydride,4 we would expect the followin: equilibria t o obtain in a solution of o-ben7oyllx~iizoic acid in perfluorohutvric aiihydride I
0
+ iC,FC-CO)zO
-t c r;coori
J I J t CF,COO
(:;)
cc 1 0 1 I c I
0
I11 IJ11
\c=o I11
0
cl
CUI'?
0
(5)
The presence of I11 in perfluorobutyric anhydride solutions is suggested by the ready conversion of o-(p-t-butylbenzoy1)-benzoic acid to 2-f-butylanthraquinone by this reagent. The presence of I1 is suggested by the fact that o-benzoylbenzoic acid and benzene react in peduorobutyric anhydride to give low yields of 3,3-diphenylphthalide. However, o-(p-t-butylbenzoy1)-benzoicacid is recovered unchanged after refluxing with benzene and perfluorobutyric anhydride for 30 hours. With o-p-toluylbenzoic acid a more complex ionization, involving the methyl group, becomes possible. In a strong acid, HA, the species shown in the equations below may occur
The presence of the ion I1 is demonstrated further by the fact t h a t when o-benzoylbenzoic acid in sulfuric acid is treated with benzene, toluene or tbutylbenzene, the resultant products are 3,3-diphenylphthalide, 3-phenyl-3-p-tolyl phthalide or :3-phenyl-3-(p-t-butylphenyl)-phthalide (IV), respectively, all obtained in yields of better than 0 707,. The structure of I V follows from its preparation from o-(p-t-butylbenzoy1)-benzoic acid2 and benzene, as well as from benzoylbenzoic acid and t-butylbenzene, from comparison of its ultraviolet spectrum with the spectrum of the known 3,3-diphenylphthalide, and from an independent synthec 0 sis by a method used for the preparation of 3,Xtliphenylphthalide. In polyphosphoric acid,3 too, benzoylbenzoic acid ionizes to give the ions I1 and 111. A4televated temperatures (100-140"), benzoylbenzoic acid gives anthraquinone, and o-(p-t-butylbenzoyl)\ II benzoic acid gives 2-t-butylanthraquinone. '' Ait lower temperatures (80°), in the presence of ben- 1.1 + A zene, mixtures of the phthalides and the anthraquinones are obtained, and, in the cold, benzoylbenzoic acid and benzene react to give a 907, yield of 3,X-diphenylphthalide. Like polyphosphoric acid, perfluorobutyric anhydride is a strong dehydrating agent, which gives The reactions of o-p-toluylbenzoic acid in sulfuric rise during reaction to the relatively strong acid, acid indicate ionization to VI and VII. Thus V is perfluorobutyric acid. By analogy with perfluoro- cyclized readily to 9-methylanthraquinone by sul( 1 ) A . H. Gleasoii a n d C,. Dvugherty, THIS J O U R N A L , 51, 310 furic acid and gives 3-phenyl-3-p-tolylphthalide (1929); M . S Newman, ibid , 64, 2324 (1942); C. W. Deane, ibifi.. when treated with benzene in cold sulfuric acid. 67, 329 (1945); \ I S. Newman, H . (;, Kuivila a n d A . B. G a r r e t t , i b i d , 67, 704 (1945). ( 2 ) A. 'I.. P e t e r 5 and I: 1 1 , Rowe, J . Chem. S o c . , 181 (1945). Weber, 'I'HIS J O I J K N A r . , 72, "962. 2 < ( f i i 1 1 I< Srl\cler ancl I?. 1 1 , 1 I
