A survey of the anodic electrochemistry of a number of ortho ‐ and meta ‐substituted anilines in at carbon paste and graphite cloth electrodes has been carried out. It was found that the electrogenerated cation radicals decompose to form the correspondingly substituted benzidines and 4‐aminodiphenylamines by tail‐to‐tail and head‐to‐tail coupling routes, respectively, in agreement with previous studies. Steric restraints hinder or exclude benzidine formation in some systems. The 4‐aminodiphenylamines undergo hydrolytic degradation by different routes for the ortho ‐ and meta ‐substituted derivatives, but in both cases 2‐substituted p ‐benzoquinones are the end product. The quinones with electron‐withdrawing substituents undergo a 1,4‐addition of water to form substituted trihydroxybenzene derivatives which are also electroactive. Products and intermediates formed were verified, where possible, by comparison with authentic samples. Preparative‐scale electrolyses resulted in substantial yields of some of the substituted p ‐benzoquinones of a magnitude comparable with chemical oxidations. A reaction mechanism is proposed which is consistent with the electroanalytical data and products formed for the series of compounds.
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Hand et al. (1978) studied this question.