The polarography of some substituted azobenzenes in acetonitrile. II. Identification of reduction products

Abstract

The reduction products of azobenzene and 4-nitroazobenzene in acetonitrile were investigated by polarography and ultraviolet-visible spectrophotometry after generation by controlled potential electrolysis. The results obtained indicate that azobenzene is reduced in two steps to give firstly the monoanion and secondly the monoprotonated form of the dianion, whereas 4-nitroazobenzene gives the monoanion and the dianion, respectively, as the products of the two one-electron reduction steps. The azobenzene monoanion undergoes a very slow disproportionation (k = 8.2 dm³ mol^-1 min^-1) to produce azobenzene and the monoprotonated dianion in equimolar amounts. The second reduction products of both compounds are stable in the absence of oxygen.