Oxidation of benzene to phenols with molecular oxygen promoted by copper(I) chloride

Abstract

Benzene suspended in aqueous sulphuric acid solution was hydroxylated with O₂ in the presence of copper(I) chloride to give phenol and hydroquinone in yields of 24 and 8%, respectively. The active species generated from the Cu^I–O₂ system was shown to be hydroxyl radical from two pieces of evidence. It was suggested that hydroquinone is produced via an intermediate peroxyl radical, which is formed by the reaction of hydroxycyclohexadienyl radical with O₂.