Preparation of Phorone

Abstract

Abstract A new method for preparation of 2,6-dimethylhepta-2,5-dien-4-one (4; phorone) from isobutene and carbon tetrachloride is described. A redox addition of carbon tetrachloride to isobutene in the presence of ferric chloride, benzoin, and diethylamine hydrochloride yielded 3-methyl-1,1,1,3-tetrachlorobutane (1). 2,6-Dimethyl-2,4,4,6-tetrachloroheptane (2) was obtained by the addition of 1 to isobutene or the twofold addition of carbon tetrachloride to isobutene. Treating 2 with ethanolic potassium hydroxide gave 2,6-dimethylhepta-1,5-dien-3-yne (3). Hydration of 3 by treating with methanolic boron trifluoride in the presence of mercuric oxide and with aqueous sulfuric acid gave 4.