Magnetic nanoparticles (MNPs), prepared by co-precipitation method, were coated using hydrolysis of tetraethyl orthosilicate (TEOS) under basic conditions. The core-shell structured supporters were further grafted by AlCl₃ to obtain the finally catalyst AlCl₃@MNPs, which was fully characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM), indicating the successful immobilization of AlCl₃ on the surface of the MNPs through coordination bond, and the magnetic nanoparticles supported aluminum chloride AlCl₃@MNPs was used in the thia-Michael addition tandem reactions. The as-prepared catalyst AlCl₃@MNPs promoted smoothly the reaction of amines, carbon disulfide and α,β-unsaturated carbonyl compounds to achieve good to excellent product yields of 59%~99%. Large surface area, excellent dispersion of catalyst in reaction solution and coordinative bond between AlCl₃ and hydroxyl cluster in MNPs ensure the highly catalytic efficiency. In addition, AlCl₃@MNPs can be readily recovered with external magnetic field and recycled for 10 times without significant loss of catalytic activity, demonstrating its advantage over the precursor AlCl₃ and excellent potential in industrial application.

Key words: magnetic nanoparticles, thia-Michael addition, recyclability, green chemistry