Green oxidation of sulfides to sulfoxides and sulfones with H2O2 catalyzed by ionic liquid compounds based on Keplerate polyoxometalates

Abstract

The hybrid catalyst of (NH4)2(MimAm)40[Mo132O372(CH3COO)30(H2O)72] (MimAm=3-Aminoethyl-1-methylimidazolium) was synthesized by self-assembly strategy. Catalyst was successfully used in the selective oxidation of various sulfides to corresponding sulfoxides and sulfones. All reactions were performed in water as a green solvent by 30% aqueous hydrogen peroxide as a green oxidant under mild reaction conditions. The catalyst showed high conversion and excellent selectivity toward a varied range of substrates and demonstrates excellent chemoselectivity in which other active functional groups such as hydroxyl and CC bond have been tolerated. Also, this hybrid catalyst could be simply separated by filtration, and showed excellent reusability without loss of activity after seven cycles.