Oxo-vanadium Schiff base supported on Fe3O4 nanoparticles as a magnetically separable nanocatalyst for epoxidation of olefines

Oxidative catalysis is an important part of research for the preparation of chemical products in industry and chemistry. Oxidation in the presence of metal that has the ability to activate the oxidant for oxidation reaction is one of the most important chemical reactions [1]. In the last decade, due to the rapid development of nanoscience, nanocatalysts developed for different reactions such as C-C coupling and oxidation reactions. The separation of nanocatalysts using magnetic nanoparticles enables us to easily recover nanocatalysts after reaction. Also, due to the size of nanoparticles, magnetic nanocatalysts exhibit high activity [2]. A new magnetically recoverable nanocatalyst has been developed via covalent grafting of the vanadyl acetylacetonate complex onto silica-coated magnetic nanoparticles (MNPs) was functionalized with 3-APTS. The nanocatalyst was characterized by elemental analysis (CHN), FT-IR, X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), inductively coupled plasma optical emission spectrometry (ICP-OES) and thermogravimetric analysis (TGA). The resulting nanoparticles were used as a recyclable catalyst for the epoxidation of olefines (Scheme 1). To find suitable condition for epoxidation reactions, different parameter such as solvent, temperature, reaction time, amount of the nanocatalyst and oxidant/substrate molar ratio has been investigated. Eventually, conversion of various substrates is measured by gas chromatography (GC). To examine the stability and reusability of the nanocatalyst, at the end of each reaction, the nanocatalyst was magnetically separated from the reaction mixture, washed with C2H4Cl2 and dried to prepare for the next reaction.