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

Abstract

Oxidation of cycloolefins (cyclohexene, cyclooctene, and cyclododecene) with a 30% solution of hydrogen peroxide at 65 °C in the presence of heteropoly acids (HPA) H3PW12–xMoxO40 (x = 0—12), which are precursors of active peroxo complexes, and phase transfer catalysts Q+Cl–, where Q+ is the quaternary ammonium cation containing C4—C18 alkyl groups or [C5H5NC16H33]+, was studied. The catalytic activity decreases in the HPA series: H3PW12O40 > H3PW9Mo3O40 > H3PW6Mo6O40 > H3PW3Mo9O40 > H3PMo12O40. The state of the H3PW12O40—I2I2 system was studied using UV, IR, and 31P NMR spectroscopies with variation of the [H2O2] : [HPA] ratio from 2 to 200 during cyclohexene epoxidation. Despite different catalytic precursors, the reaction proceeds through the same peroxo complex.