Hydrothermal synthesis of CuFe₂O₄ magnetic nanoparticles as active and robust catalyst for N-arylation of indole and imidazole with aryl halide

Abstract

Spinel ferrite magnetic nanoparticles are superior to the conventional catalysts. Here we report the synthesis of different types of spinel ferrite nanoparticles, MFe₂O₄ (M= Cu, Mn, Mg, Co, Ni), by a hydrothermal method. The prepared spinel ferrite nanoparticles were used for the N-arylation reaction of indole with iodobenzene. Among these CuFe₂O₄ nanoparticles exhibited the best activity and selectivity for N-arylation under ligand free condition. The prepared spinel ferrite microspheres were well characterised by using various characterization techniques such as TEM, XRD, XPS, SEM, EDXA, FT-IR, N₂ adsorption desorption measurements and TGA. The effect of various parameters were studied such as solvent, base, speed of agitation, mole ratio, catalyst loading and temperature in the reaction of indole with iodobenzene. Best conversion and yield were achieved at 110 °C and 1×10^-3 g/cm³ catalyst loading. Notably, CuFe₂O₄ magnetic nanoparticles were completely recovered and could be reused six times without any noticeable loss of activity. Reaction mechanism and kinetics are also presented.