Oxidations of aromatic amines by superoxide ion

Abstract

Superoxide ion acts as a mild and highly selective oxidizing agent for aromatic amines. Aniline and α-naphthylamine were not oxidized, but β-naphthylamine formed dibenzo[a,h]phenazine, dibenzo- [a,i]phenazine and 2,2'-azonaphthalen-1-ol. o-and p-Diamines are oxidized to diaminoazobenzenes but m-diamines are unreactive. Similarly o- and p-aminophenols are oxidized to dihydroxyazo- benzenes but m-aminophenols are unaffected, and o-mercaptoaniline forms the disulfide. The oxidations are considered to be free-radical processes, initiated by hydrogen abstraction by superoxide from the substrates. The biological significance of the results is discussed.