The organic-inorganic hybrid support was synthesized by covalently anchoring N-octyldihydroimidazolium cation fragment onto SiO2 (1-SiO2). The modified support 1-SiO2 was characterized by solid-state NMR of 13C, 29Si, and 31P, IR spectroscopy, and elemental analysis. The results showed that the structure of dihydroimidazolium skeleton was preserved on the surface of SiO2. The modified support 1-SiO2 could act as a good anion exchanger, and the catalytically active polyoxometalate anion, [?-1,2-H2SiV2W10O40]4? (I) developed by our research group, could be immobilized onto the support with the stoichiometric anion exchange (I/1-SiO2). The catalytic performance for the oxidation of olefins and sulfides with hydrogen peroxide as a sole oxidant was investigated with I/1-SiO2. The supported catalyst I/1-SiO2 showed high stereospecificity, diastereoselectivity, regioselectivity, and the high efficiency of hydrogen peroxide utilization for the oxidation of various olefins and sulfides without the loss of the intrinsic catalytic nature of the corresponding homogeneous analogue of I. The oxidation was immediately stopped by the removal of the solid catalyst, and vanadium and tungsten species hardly be found in the filtrate after removal of the catalyst. These results could rule out any contribution to the observed catalysis from the vanadium and tungsten species that leached into the reaction solution and the observed catalysis was truly heterogeneous in nature. In addition, the catalyst was reusable for both epoxidation and sulfoxidation without the loss of the catalytic performance.
Polyoxometalate, Epoxidation, Olefins, Hydrogen Peroxide, Vanadium