Nano-Fe3O4@SiO2-SO3H: A magnetic, reusable solid-acid catalyst for solvent-free reduction of oximes to amines with the NaBH3CN/ZrCl4 system

In this study, the immobilization of sulfonic acid on silica-layered magnetite was carried out by the reaction of ClSO3H with silica-layered magnetite. The prepared magnetic nanoparticles of Fe3O4@SiO2-SO3H were then characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and transmission electron microscopy. The sulfonated nanocomposite exhibited excellent catalytic activity and reusability in the reduction of various aldoximes and ketoximes with NaBH3CN in the presence of ZrCl4. All reactions were carried out under solvent-free conditions (r.t. or 75-80 degrees C) within 3-70min to afford amines in high to excellent yields.