SYNTHESIS OF ALKYL SUBSTITUTED PARA-BENZOQUINONES FROM THE CORRESPONDING PHENOLS USING MOLECULAR-OXYGEN CATALYZED BY COPPER(II) CHLORIDE-AMINE HYDROCHLORIDE SYSTEMS

2,4,6-Trimethylphenol was effectively oxidized to trimethyl-p-benzoquinone with molecular oxygen in the presence of a catalytic amount of copper(II) chloride-amines in alcohol at ambient temperature. Various amines could be used as a co-catalyst in the presence of acids, and especially hydroxylamine hydrochloride and acetone oxime coupled with hydrochloric acid showed high activity. 2,6-Dimethyl-p-benzoquinone was also obtained from 2,6-dimethylphenol in good yield in this catalytic oxidation system.