Magnetically Separable Gold Catalyst for the Aerobic Oxidation of Amines

A magnetically separable, recyclable gold catalyst consisting of gold nanoparticles supported on intimately mixed superparamagnetic ceria/iron oxide has been prepared by simple addition of the preformed mixed oxide support and the gold precursor, Au(OAc)(3), to the reaction mixture of,the aerobic oxidation of amines. The catalyst was characterized by means of X-ray diffraction (XRD), N-2 adsorption, superconducting quantum-interference device (SQUID) measurements, time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning transmission electron microscopy (STEM), and scanning electron microscopy with an energy-dispersive X-ray spectrometer (SEM-EDAX). Catalytic tests with various amines showed high selectivity to the corresponding imines (87-100%), and good separation efficiency and recyclability of the catalyst.