Efficient and selective oxidation of alcohols and hydrocarbons catalyzed by oxovanadium(IV) unsymmetrical salophen complex supported on silica-coated CoFe2O4 magnetic nanoparticles

Abstract

In this study, the catalytic activity of an oxovanadium(IV) unsymmetrical salophen complex immobilized on chloro-functionalized silica-coated CoFe₂O₄ magnetic nanoparticles CoFe₂O₄@SiO₂@CPTMS@VO(salophen-OH), in which salophen-OH = 4-[(E)-{(2-[(E)-2-hydroxybenzylidene)amino]phenyl}imino)methyl]benzene-1,3-diol was explored in the oxidation of alcohols and hydrocarbons. This heterogeneous nanocatalyst showed high activity and selectivity in oxidizing various primary and secondary alcohols to the equivalent aldehydes and ketones with 30% H₂O₂ as a green oxidant in polyethylene glycol (PEG) as an eco-friendly solvent at 80 °C. Furthermore, the above catalyst demonstrated significant catalytic efficiency in the alkene epoxidation and alkane hydroxylation using tert-butyl hydroperoxide (tert-BuOOH), and the corresponding products were achieved in good to excellent yields in acetonitrile at ambient temperature. This magnetic nanocatalyst can be easily separated from the reaction mixture utilizing an external magnet and reused up to five times without significant activity loss. Moreover, the recovered catalyst’s structure was scrutinized using Fourier transform infrared (FT-IR), vibrating sample magnetometry (VSM), and X-ray diffraction (XRD) techniques, which confirmed that the structure of the catalyst remained unaltered post-recovery.