Immobilization of an oxovanadium(IV) tetradentate Schiff base complex on clay as a recyclable heterogeneous catalyst for the epoxidation of olefins

The vanadyl Schiff base complex of N,N'-bis(5-[(triphenylphosphoniumchloride)-methyl-salicylidine) meso-stilben-diamine)] was synthesized and immobilized on sodium montmorillonite. The supported complex was characterized by X-ray diffraction, IR spectroscopy, diffuse reflectance spectroscopy and atomic absorption spectroscopy techniques. The infrared and diffuse reflectance spectra of the immobilized complex show that the vanadium(IV) Schiff base complex was physically entrapped within sodium montmorillonite. The new heterogeneous catalyst shows excellent catalytic activity in the epoxidation of olefins using tert-butylhydroperoxide in acetonitrile. In this report, the supported vanadyl complex exhibited 100 % selectivity for epoxidation with 98 % conversion for cyclohexene. The catalytic activity and selectivity of heterogeneous catalyst have not changed after four times of reusing.