Epoxidation of alkenes using immobilized vanadyl Schiff base complex on montmorillonite as an efficient recyclable heterogeneous catalyst with tert-butyl hydroperoxide

Oxovanadium(IV) Schiff base complex of N,N′-bis(5- [(triphenylphosphoniumchloride)-methyl-salicylidinenaphthal-diamine)] was synthesized, characterized and immobilized on sodium montmorillonite as a heterogeneous catalyst. The net Schiff base complex and supported complex were characterized by X-ray diffraction spectroscopy, IR spectroscopy, diffuse reflectance spectroscopy and atomic absorption spectroscopy techniques. The diffuse reflectance spectra data and IR spectra of the supported Schiff base complex show that the complex was physically entrapped within sodium montmorillonite. The novel heterogeneous catalyst shows excellent catalytic activity in epoxidation of olefins using tert-butylhydroperoxide in acetonitrile. In this report, the supported vanadyl complex exhibited 100% selectivity for epoxidation with 91% and 90% conversion for cyclohexene and cyclooctene, respectively. The supported oxovanadium(IV) complex gave higher percent of conversion of olefins than neat oxovanadium(IV) Schiff base complex.