Peroxomolybdate supported on water soluble polymers as efficient catalysts for green and selective sulfoxidation in aqueous medium

Abstract

Peroxomolybdenum(VI) species immobilized on linear water soluble polymers formulated as, [MoO(O2)2(sulfonate)]–PS [PS=poly(sodium vinyl sulfonate)] (PSMo) and[Mo2O2(O2)4(carboxylate)]–PA [PA=poly(sodium acrylate)](PAMo) served as efficient and recyclable catalysts for selective oxidation of organic sulfides to sulfoxide in water with 30% H2O2. The new polymer anchored complex, PSMo has been prepared by reacting H2MoO4 and 30% H2O2 with macromolecular ligand, poly(sodium vinyl sulfonate) and characterized by elemental analysis, spectral studies (FTIR, Raman, 13C NMR, 95Mo NMR, UV–vis), SEM, EDX and TGA-DTG analysis. The catalytic protocol effects clean and facile oxidation of a wide range of sulfides to afford pure sulfoxides with high TOF and excellent chemoselectivity at ambient temperature,with an easy work-up procedure. The catalysts can be regenerated in-situ and recycled at least up to ten consecutive reaction cycles without significant loss of activity and are amenable for ready scalability. The catalytic procedure thus provides an ecologically sustainable alternative as it involves water as solvent, H2O2 as green oxidant, a recyclable non-polluting catalyst, and is absolutely free from halide, organic co-solvent or co-catalyst. This is the first catalytic protocol for selective aqueous oxidation of sulfides using a catalytic system based on peroxometal species supported on water soluble polymers.