Lacunary Keggin Polyoxotungstate As Reaction-Controlled Phase-Transfer Catalyst for Catalytic Epoxidation of Olefins

A new reaction-controlled phase-transfer catalyst system, lacunary Keggin polyoxotungstate [C7H7N(CH3)(3)](9)PW9O34 has been synthesized and used for catalytic epoxidation of olefins with H2O2 as the oxidant. Infrared spectra were used to analyze the behavior of the phase transfer of catalyst. In this system, the catalyst not only can act as homogeneous catalyst but also as heterogeneous catalyst to be easily filtered and reused. The epoxidation reaction is clean and exhibits high conversion and selectivity as well as excellent catalyst stability.