Alkene epoxidation with hydrogen peroxide catalyzed by vanadium-substituted polyoxotungstates

摘要

The Keggin-type vanadium-substituted polyoxotungstates were used as catalysts for the epoxidation of alkenes in homogeneous reaction media using hydrogen peroxide. The efficiency for utilization of hydrogen peroxide and the selectivity to the epoxide greatly depended on the vanadium centers and divanadium-substituted [gamma-1, 2-SiV_2W_(10)O_(40)]~(6-) showed the highest activity and selectivity to the epoxide. ~(51)V NMR, IR, and UV-vis spectra showed that [gamma-1, 2-SiV_2W_(10)O_(40)]~(6-) was stable under the conditions used. The reaction mechanism of the catalytic epoxidation by [gamma-1, 2-SiV_2W_(10)O_(40)]~(6-) was also discussed.