Epoxidation of cycloolefins with hydrogen peroxide in the presence of heteropoly acids combined with phase transfer catalyst

摘要

Oxidation of cycloolefins (cyclohexene, cyclooctene, and cyclododecene) with a 30% solution of hydrogen peroxide at 65 deg C in the presence of heteropoly acids (HPA) H_3PW_(12-x)Mo_xO_(40) (x = 0-12), which are precursors of active peroxo complexes, and phase transfer catalysts Q~+Cl~-, where Q~+ is the quaternay ammonium cation containing C_4-C_(18) alkyl grops or [C_5H_5NC_(16)H_(33)]~+, was studied. The catalytic activity decreases in the HPA series: H_3PW_(12)O_(40) > H_3PW_9Mo_3O_(40) > H_3PW_6Mo_6O_(40). The state of the H_3PW_(12)O_(40)-H_2O_2 system was studied using UV, IR, and ~(31)P NMR spectroscopies with variation of the [H_2O_2]: [HPA] ratio from 2 to 200 during cyclohexene epoxidation. Despite different catalytic precursors, the reaction proceeds through the same peroxo complex.