Oxovanadium hydrazone complex immobilized on magnetic nanoparticles: A reusable and efficient nanocatalyst for the oxidation of norbornene

Abstract

A new oxovanadium hydrazone complex ([VOL(H2O)]) was synthesized. Then, after anchoring the hydrazone ligand (H2L) on the chloropropyl–modified, silica-coated magnetic support and reacting it with VO(acac)2, the heterogeneous nanocatalyst (Fe3O4@SiO2-CPTMS-L-VO(OEt)) was obtained. Characterization of [VOL(H2O)] and Fe3O4@SiO2-CPTMS-L-VO(OEt) were performed by applying different techniques including XRD, TGA, FT‐IR, 1H NMR, 13C{1H}‐NMR, mass, UV–Vis, XPS, VSM, TEM, SEM, and elemental analysis. The catalytic potential of the homogeneous complex and heterogeneous nanocatalyst were assessed for oxidizing various olefins (norbornene, styrene, α-methyl styrene, cyclooctene, and cyclohexene) applying tert-butyl hydroperoxide (TBHP) as an oxidizing agent. Comparing the catalytic activity of [VOL(H2O)] and Fe3O4@SiO2-CPTMS-L-VO(OEt) manifested, that the heterogeneous nanocatalyst was more efficient not only for its simple magnetic separation and effective recyclability but also for its higher turnover number (TON) and shorter reaction time. The findings showed that the function of Fe3O4@SiO2-CPTMS-L-VO(OEt) nanocatalyst was particularly notable for oxidizing norbornene with more than 99% conversion and 84% selectivity for norbornene epoxide.