Sn-exchanged hydrotalcites as catalysts for clean and selective Baeyer-Villiger oxidation of ketones using hydrogen peroxide

A Sn-doped hydrotalcite (Sn/HT) catalyst prepared by ion-exchange technique is found to be an active and selective catalyst for the liquid phase Baeyer-Villiger (BV) oxidation of cyclic ketones in acetonitrile using hydrogen peroxide (H2O2) as oxidant. Different reaction parameters such as effect of solvent, Sn content, reaction temperature and catalyst-to-substrate ratio are studied. The activity of the catalyst for the selective BV oxidation of ketones is attributed to the presence of active Sn sites in the interstitial position of hydrotalcite support. Sn sites activate the carbonyl group of ketones followed by a nucleophilic attack by the active peroxide species (peroxycarboximidic acid by reaction of acetonitrile and H2O2) to form a Criegee adduct that rearranges to give the lactone. (C) 2002 Elsevier Science B.V. All rights reserved.