Synthesis and characterization of immobilized Mo VI complex on modified Fe3O4 nanoparticles as catalyst for epoxidation of olefins

A covalently grafted N-(3-propyl)-2- pyridylmethanimine Schiff base ligand (L) was introduced onto the surface of silica coated magnetic nanoparticles (L/SCMNPs) through the condensationreaction of 2-pyridinecarboxaldehyde with 3- aminopropyl functionalized silica coated magneticnanoparticles. Treatment of the grafted Schiff base ligand with the MoO2(Cl)2(THF)2 led to the formation of an immobilized dichlorodioxomolybdenum(VI)-pyridyliminecomplex (MoO2Cl2L/SCMNPs). Successful surface functionalization and immobilization of molybdenum complex on the functionalized surface of magnetic nanoparticles were confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction(XRD), thermal analysis, scanning electron microscopy (SEM), transmittance electron microscopy (TEM) and energy dispersive X-rayspectrometry (EDX). The catalytic activity ofimmobilized complex (MoO2Cl2(L)/SCMNPs) in epoxidation of some olefins with tert-butyl hydroperoxide (TBHP) was investigated and theinfluence of important parameters such as type of solvent, reaction time and the amount of catalyst on epoxidation yield were studied. Conversions of 81- 99% with 92-100% selectivity toward epoxide products were obtained for different olefins includingstyrene, cyclooctene and cyclohexene.The results showed that the synthesized magnetic martial is an efficient, highly selective, reusable and magneticallyseparable heterogeneous catalyst for olefin epoxidation.