Quaternary ammonium salts. Part III. The formation and decomposition of p-aroylphenylethyldimethylammonium salts

Abstract

The formation of these salts (I) is governed by the --M effect of the aroyl group, which is the combined effect of the electronic displacements due to the carbonyl and the aryl group. Thermal decomposition of the iodides (I ; X = I) leads, with one exception, to formation of the corresponding AT-ethyl-Nmethylaminobenzophenones (B) . However, decomposition with alcoholic sodium methoxide gives rise to a mixture of the base (B) and the methyl ether (A). The ratio of A to B depends on the nature and on the position of the substituent in the aryl group.THIS work deals with the effect of the fi-aroyl group on the formation and decomposition of quaternary ammonium salts (cf. Part I, Fahim and Galaby, J., 1950, 3529 ; Part I1 *).N -9 -Aroylphenyl-N-ethyl-NN-dimethylammonium ethyl sulphates (I ; X = EtSO,) were formed by heating the corresponding tertiary bases with ethyl sulphate at 115-130". The quaternary salt was estimated as picrate or iodide. Formation of the quaternary salt is inhibited by increase of the --M effect of the aroyl group, which is the combined effect of the electronic displacements due to the carbonyl and the aryl group.The relative ease of formation of the quaternary salt from 4-dimethylamino-4'-methylbenzophenone (I1 ; R = Me) is due to the decrease in the --M effect of the carbonyl group caused by the +I and probably by the hyperconjugation effect of the methyl group.

Synthesis of Diaryl Ketones through Oxidative Cleavage of the C–C Double Bonds in N-Sulfonyl Enamides

“…1 (4-(Ethyl(methyl)amino)phenyl)(phenyl)methanonemethanone (4d). 33 Yellow oil (43.6 mg, 91%). R f = 0.4 (EtOAc:hexane = 1:10).…”