The chemistry of hydroxyquinones. Part II. The autoxidation of 3,6-dimethylbenzene-1,2,4-triol

Abstract

A spectroscopic and kinetic study of the autoxidation of 3,6-dimethylbenzene-1,2,4-triol has shown the first stage to proceed by way of a semiquinone intermediate to give the hydroxyquinone, dihydroxybiphenodiquinone, and hydrogen peroxide as the initial products. Subsequent reaction of the hydroxyquinone with alkali gives 2,5-dihydroxy-3,6-dimethylbenzoquinone and further hydrogen peroxide. This reaction competes with a dimerisation of the quinone, yielding a colourless compound C₁₆H₁₈O₇, and, particularly in the absence of oxygen, a reduced from of the biphenodiquinone. This second stage is further complicated by a reaction between the hydroxyquinone and alkaline hydrogen peroxide which gives a cyclopentane derivative.