Novel approach to benzimidazoles using Fe3O4 nanoparticles as a magnetically recoverable catalyst

Magnetically recoverable Fe3O4 nanoparticles have been synthesized as a catalyst for the cyclocondensation of 1,2- phenylenediamines with orthoesters under solvent-free conditions. Catalyst loadings can be as low as 1 mol to give high yields of the corresponding benzimidazole derivative at 80°C. This green method offers significant advantages in terms of its simplicity, low catalyst loadings, high product yields, and non-toxic nature. The Fe3O4 nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. © 2012 Dalian Institute of Chemical Physics, the Chinese Academy of Sciences.