Reactions of diosphenol and 3, 6-dimethyl-1, 2-cyclohexanedione with iodine-copper (II) acetate in acetic acid-water (5: 1) at 80° C gave the respective 3-hydroxy-2, 5-dialkyl-1, 4- benzoquinone in 25–80% yields. 2-t-Butyl-5-methylcyclohexanone similarly gave the corresponding 3-hydroxy-1, 4-benzoquinone in 66% yield.