Immobilized antimony species on magnetite: a novel and highly efficient magnetically reusable nanocatalyst for direct and gram-scale reductive-coupling of nitroarenes to azoarenes

In this study, magnetic nanoparticles of Fe(3)O(4)@SbF(x) from the immobilization of SbF(3) on magnetite were synthesized. The prepared nanocomposite system was then characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry and inductively coupled plasma optical emission spectroscopy. Next, the catalytic activity of Fe(3)O(4)@SbF(x) MNPs was highlighted by one-pot reductive-coupling of aromatic nitro compounds to the corresponding azoarene materials with NaBH(4). The reactions were carried out in refluxing EtOH within 6–25 min to afford the products in high yields. The reusability of the Sb-magnetite system was also studied for 6 consecutive cycles without significant loss of catalytic activity. This synthetic protocol provided several advantages in terms of introducing a novel catalytic system based on antimony species for direct and gram-scale preparation of azoarenes from nitroarenes, low loading of the nanocatalyst, mild reaction conditions, using ethanol as a green and economic solvent and high yield of the products.