Covalent supporting of novel dioxo-molybdenum tetradentate pyrrole-imine complex on Fe3O4 as high-efficiency nanocatalyst for selective epoxidation of olefins

A novel Mo(VI) tetradentate Schiff base complex based on two pyrrole-imine donors was anchored covalently on Fe3O4 nanoparticles and characterized using physicochemical techniques. The catalytic epoxidation process was optimized in terms of the effects of solvent, reaction temperature, kind of oxidant and amount of oxidant and catalyst. Then the novel heterogeneous nanocatalyst was used for the efficient and selective catalytic epoxidation of internal alkenes (cyclohexene, cyclooctene, -pinene, indene and trans-1,2-diphenylethene) and terminal alkenes (n-heptene, n-octene, n-dodecene and styrene) using tert-butyl hydroperoxide (70% in water) as oxidant in 1,2-dichloroethane as solvent. The prepared nanocatalyst is very effective for the selective epoxidation of cis-cyclooctene with 100% conversion, 100% selectivity and turnover frequency of 1098 h(-1) in just 30 min. The magnetic nanocatalyst was easily recovered using an external magnetic field and was used subsequently at least six times without significant decrease in conversion.