Cr-doped magnetite for the catalytic radical amination of C(sp3)–H in toluene with NH3 and H2O2

Abstract

The direct catalytic amination of C(sp3)–H is difficult to achieve but significant. The compound of Fe2.35Cr0.65O4, prepared by the oxidation–precipitation method, was characterized by X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller, X-ray photoelectron spectroscopy, and inductively coupled plasma spectrometry, and used to catalyze the decomposition of hydrogen peroxide to hydroxyl-free radical, which sequentially reacted with ammonia and toluene to produce benzylamine. Results showed that Fe2.35Cr0.65O4 with high Cr content, particularly the outside surface, could well better catalyze hydrogen peroxide to hydroxyl-free radical and its transformation. Under the conditions of pH < 6, 30 °C, and the NH3 amount, maintaining the match of one hydroxyl-free radical one by the process control, toluene in the other phase of the reaction system was converted into benzylamine with 30% yield. The catalytic radical amination of C(sp3)–H in toluene was achieved without any oriented group.