Vanadium-Substituted Tungstophosphoric Acid (H5PV2W10O40): A Green and Reusable Catalyst for Highly Efficient Acetylation of Alcohols and Phenols under Solvent-free Conditions

Vanadium-substituted tungstophosphoric acid, H5PV2W10O40 (HPVW), was used as a novel, efficient and green catalyst for acetylation of alcohols and phenols under solvent-free conditions. Various primary, secondary and tertiary alcohols were acetylated with acetic anhydride as an acetylating agent under solvent-free conditions in the presence of catalytic amount of HPVW at room temperature. The corresponding acetates were obtained in excellent yields within a very short reaction time. The catalyst can be recycled several times, so that this process could find useful applications. Also, phenols were acetylated in quantitative yield albeit after longer reaction time in comparison with alcohols. The selective acetylation of an alcoholic OH group in the presence of a phenolic OH group could be achieved by the appropriate choice of the reaction time. The excellent activity of HPVW was demonstrated by the high yields obtained for acetylation of alcohols and phenols having electron-withdrawing substituents.