CuO-decorated magnetite-reduced graphene oxide: a robust and promising heterogeneous catalyst for the oxidative amidation of methylarenes in water via benzylic sp3 C–H activation

Abstract

A magnetite-reduced graphene oxide-supported CuO nanocomposite (rGO/Fe₃O₄–CuO) was prepared via a facile chemical method and characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Brunauer–Emmett–Teller (BET) analysis, vibrating-sample magnetometry (VSM), and thermogravimetric (TG) analysis. The catalytic activity of the rGO/Fe₃O₄–CuO nanocomposite was probed in the direct oxidative amidation reaction of methylarenes with free amines. Various aromatic and aliphatic amides were prepared efficiently at room temperature from cheap raw chemicals using tert-butyl hydroperoxide (TBHP) as a “green” oxidant and low-toxicity TBAI in water. This method combines the oxidation of methylarenes and amide bond formation into a single operation. Moreover, the synthesized nanocomposites can be separated from the reaction mixtures using an external magnet and reused in six consecutive runs without a noticeable decrease in the catalytic activity.