Amine oxidation and the chemistry of quinone imines. Part II. 2,5-Di-methoxy-4-t-butylaniline

The oxidation of 2,5-dimethoxy-4-t-butylaniline (1) by alkaline ferricyanide or silver oxide gives 2,2′,5,5′-tetramethoxy-4, 4′-di-t-butylazobenzene (2) and 3,8-dimethoxy-2,7-di-t-butylphenazine (3). Chromatographic separation of the oxidation products on neutral alumina gives rise to six other products, including three N-aryl-p-quinone imines (4), (6), and (7), a tetrameric product (5), and a phenoxazone (8). Evidence is presented for the structures of these compounds, and their origin is discussed. The formation of the phenazine (3) provides clear evidence for the cyclisation of an intermediate N-aryl-o-quinone di-imine (11) under these conditions. Isolation of the debutylated quinone imine (7) substantiates assumptions made in the previous paper.