A spectroscopic study on the 12-heteropolyacids of molybdenum and tungsten (H3PMo12−nWnO40) combined with cetylpyridinium bromide in the epoxidation of cyclopentene

The epoxidation of cyclopentene with hydrogen peroxide catalyzed by H3PMo6W6O40 combined with cetylpyridinium bromide as a phase transfer reagent was carried out in acetonitrile. The fresh catalysts and the catalysts under reaction condition were characterized by UV-vis, FT-IR and 31P NMR spectroscopies, which have revealed that all of the molybdotungstophosphoric acids were degraded in the presence of hydrogen peroxide to form a considerable amount of phosphorus-containing species. The active species resulted from H3PMo6W6O40 are new kinds of phosphorus-containing species, which is different from {PO4[WO(O2)2]4}3−.