Fabrication of chitosan-bond-2-hydroxy-1-naphthaldehyde Cu complex covalently linked magnetite nanoparticles as an efficient, reusable and magnetically separable catalyst for the selective oxidation of sulfides to sulfoxides using 30% H2O2 under solvent-free conditions

Abstract

The new, environmentally friendly and magnetically recoverable nanocatalyst (with a particle size about 40 nm) was successfully prepared via covalent grafting of Cu (II) onto chitosan-bond-2-hydroxy-1-naphthaldehyde coated Fe3O4 magnetic nanoparticles. Catalytic performance of the Fe3O4@chitosan-based Cu complex was evaluated through the H2O2-based oxidation of different sulphides to the corresponding sulphoxides under mild reaction conditions. The products were obtained with good to excellent yields. Moreover, the novel catalyst could be easily separated from the reaction mixture by an external magnet and recycled four times without any significant loss of its activity. The as-prepared catalyst was well characterised by fourier transform infrared, powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and thermogravimetric analysis. Also, the loading level of Cu in the Fe3O4@Chitosan-based Cu catalyst was assessed by inductively coupled plasma atomic emission analysis.