Kinetic investigation on the highly efficient and selective oxidation of sulfides to sulfoxides and sulfones with t-BuOOH catalyzed by La2O3

Abstract

The selective oxidation of various sulfides to sulfoxides by a simple, efficient, and environmentally benign method is of prime focus. In this paper, we have explored a highly efficient protocol for the oxidation of alkyl aryl sulfides to sulfoxides with high selectivities catalyzed by La₂O₃ in the presence of 70% t-BuOOH solution (water). We obtained predominantly the monooxygenated product. The over oxidation of sulfides to sulfones was not observed under these conditions. The resulting products are obtained in good to excellent yields within a reasonable time without the use of ligands and other additives. The epoxidation of the double bond as well as allylic oxidation are not observed with allyl sulfides. Sulfones can be obtained quantitatively by altering the reaction conditions. The surface morphology and the catalyst reusability were verified by XRD, AFM and SEM techniques. The surface area of the La₂O₃ was measured using BET isotherms.