Direct aerobic epoxidation of alkenes catalyzed by metal nanoparticles stabilized by the H_5PV_2Mo_(10)O_(40) polyoxometalatet

摘要

Ag and Ru nanoparticles stabilized by H_sPV_2MO_(10)O_(40), prepared by a sequence of redox reactions and supported on alpha-alumina, were effective catalysts for the direct aerobic epoxidation of alkenes in the liquid phase.The selective aerobic epoxidation of alkenes with molecular oxygen alone remains a key and largely unsolved research objective with significant commercial implications.Apparently,the major obstacle to selective direct aerobic epoxidation of alkenes is the relatively low bond strengths of allylic C-H moieties;facile allylic C-H bond scission commonly leads to(very)low epoxidation selectivity.