Selective and Reusable Oxidation of Sulfides to Sulfoxides with Hydrogen Peroxide Catalyzed by Organic-Inorganic Polyoxometalate-Based Frameworks

Several organic-inorganic polyoxometalate-based frameworks such as HSiW-MOF, PMo-MOF, HPMo-MOF and PW-MOF were prepared and characterized by Elemental analysis, UV-Vis, FT-IR and XRD. Thioanisole was used as the model of sulfur compound in the oxidation reaction. The effects of reaction time, type of solvent, amount of catalyst and oxidants in this catalytic system were investigated. At optimum conditions, PMo-MOF and PW-MOF are more active catalysts with respect to H2O2. Oxidation of various sulfides to sulfoxides using 30 % aqueous hydrogen peroxide as oxidant under mild reaction conditions in 90-100 % conversion and 95-100 % selectivity to sulfoxideswas performed. Both catalysts showed high catalytic activity in the oxidation of different sulfides with actively functional groups such as the hydroxyl group and C=C bonds. The heterogeneous catalyst (PW-MOF) could be recovered easily and reused five times without significant loss of its catalytic activity. [GRAPHICS] .