Oxidation of Methoxy- and/or Methyl-Substituted Benzenes and Naphthalenes to Quinones and Phenols By Hydrogen Peroxide In Formic Acid

Abstract

The oxidn. of a no. of arenes (methoxybenzenes, methylbenzenes, and d naphthalenes) to quinones and phenols by H2O2 in HCO2H has been examd. Methoxybenzenes were much more easily oxidized to p-benzoquinones than methylbenzenes (e.g., 1,3,5-trimethoxybenzene was oxidized to 2,6-dimethoxy-p-benzoquinone in a 75% yield and 1,2,4-trimethylbenzene to 2,3,5-trimethyl-p-benzoquinone in a 16% yield). Electron-withdrawing substituents, such as nitro, cyano, and chloro groups, lowered the conversion of reactants and changed the product selectivity from quinones to phenols. Methoxybenzonitriles were oxidized to corresponding phenols in a moderate yield (e.g., 2,6-dimethoxybenzonitrile to 3-hydroxy-2,6-dimethoxybenzonitrile in a 39% yield and a 64% selectivity).