Solvent-free synthesis of unsaturated ketones by the Saucy–Marbet reaction using simple ammonium ionic liquid as a catalyst

Abstract

Simple ammonium ionic liquids are efficient catalysts in promoting Saucy–Marbet reactions of unsaturated alcohols with unsaturated ethers to afford the corresponding unsaturated ketones, eliminating the need for volatile organic solvents. The effect of the anions and the cations of ionic liquids, quantity of ionic liquid, temperature, and chain-length of unsaturated alcohols on the reaction was investigated. The results showed that the Saucy–Marbet reaction was heavily influenced by the acidity of ionic liquid and [Et₃NH][HSO₄] had the best catalytic activity. The conversion and selectivity obtained with this method are significantly increased in comparison to those catalyzed by traditional acid. Furthermore, the ionic liquid could be easily separated and reused with a slight loss of its activity. It provided a good alternative way for the industrial synthesis of unsaturated ketones.