An electron spin resonance investigation of the intermediates and products in the basic reduction of cis- and trans-p-nitro-β-bromostyrenes

Abstract

The mechanism of chemical and electrolytic reduction of cis- and trans-p-nitro-β-bromostyrenes has been studied by e.s.r. spectroscopy. Both isomers undergo dehydrobromination by electrolytic reduction, whereas chemical reduction by potassium t-butoxide also induces debromination. The anion radicals of cis- and trans-p-nitro-β-bromostyrenes, p-nitrostyrene, p-nitrophenylacetylene, and p-nitrobenzoic acid were identified, through the corresponding e.s.r. spectra, as intermediates or products of the reactions investigated. p-Nitrophenylacetylene and p-nitrobenzoic acid were also isolated from the reaction mixture. The effects of the solvent and the counterion on the yield of electrolytic conversion of cis-p-nitro-β-bromostyrene to p-nitrophenylacetylene are also reported.