Aniline, formation Anthraquinone

Baughman (1992) measured the disappearance rate constants for a number of solvent and disperse azo, anthraquinone, and quinoline dyes in anaerobic sediments. The half-lives ranged from 0.1 to 140 days. Product studies of the azo dyes showed that reduction of the azo linkages and nitro groups resulted in the formation of substituted anilines. The 1,4-diaminoanthraquinone dyes underwent complex reactions thought to involve reduction and replacement of amino with hydroxy groups. Demethylation of methoxyanthraquinone dyes and reduction of anthraquinone dyes to anthrones also was observed. 

The numerous experiments which led to the formation of dyes at the anode, when aniline, toluidine, methylaniline,. diphenylamine, nethyldiphenylamine and naphthylamine or their salts were electrolyzed, have, however, not been scientifically investigated and, hence, still remain unsolved. The same holds true of Goppelsroder investigations concerning the oxidation of phenol and anthraquinone. The most important discovery is the fact that aniline salts smoothly yield aniline black at the anode the naphthylamine salts give naphtliylamine-violet.1... 

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