Environmentally safe magnetic/chitosan-based nickel Schiff base composite as a heterogeneous and magnetically recoverable nanocatalyst for mild and efficient reduction of nitroarenes

Catalytic reduction of harmful pollutants, like nitroarenes to important intermediates like aminoarenes is progressing in academic research. Development of heterogeneous catalysts utilizing environmentally friendly magnetic/chitosan (Fe3O4/CS) as support has gained much more attention due to its non-toxicity, low cost, availability, and easy recoverability. Herein, a new heterogeneous catalyst (Fe3O4/CS/SBz/Ni) has been prepared via the facile modification of -NH2 groups of the chitosan on the Fe3O4/CS surface with 2-[4-chlorophenylthio] benzaldehyde (SBz) and subsequent metalation of the obtained NS donors with nickel(II) cations. Various physiochemical characterizations, like Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis confirmed the correct fabrication of the expected product. Field emission scanning electron microscopy (FE-SEM) demonstrated the formation of fine and monodispersed nanoparticles. The performance of the synthesized catalyst in the reduction of various nitroarene compounds to corresponding aminoarenes was evaluated at ambient conditions. UV–vis absorption spectra were recorded at various time intervals to monitor the reaction progress at room temperature. The reduction of 4-nitrophenol (4-NP) in optimized reaction conditions (10 mg of catalyst, 0.2 mmol of NaBH4, 25 mL of H2O, room temperature, and 30 min) reached 91% conversion. The catalyst was easily separated by an external magnet and reused in the next runs without significant loss of its activity.