Oxidation by metal oxides-IX: oxidation of benzylideneacetone phenylhydrazones with nickel peroxide

Abstract

Benzylideneacetone phenylhydrazone on oxidation with nickel peroxide gave a dl-mixture of 1,1', 5,5'-tetraphenyl-3,3'-dimethyl-4,4'bipyrazoline, whereas, 2-methylbenzylideneacetone phenylhydrazone under similar conditions gave meso-1,1'-diphenyl-3,3'-dimethyl-5,5'-di-(o-tolyl)-4,4'-bipyrazoline. Similarly, meso-4,4'-bipyrazolines were formed in the oxidation of 2-chloro- and 4-methylbenzylideneacetone phenylhydrazones and furfurylideneacetone phenylhydrazone. A mixture of both dl- and meso-forms of 4,4'-bipyrazolines, however, was obtained in the oxidation of 3-chloro-, 4-chloro- and 3-methylbenzylideneacetone phenylhydrazones and piperonylideneacetone phenylhydrazone. The structures of both the dl- and meso-forms of 4,4'-bipyrazolines have been established on the basis of analytical data and spectral evidences. Mass spectral fragmentation of some of these pyrazolines have also been examined.