Chemoselective reduction of nitro and nitrile compounds using an FeO-MWCNTs@PEI-Ag nanocomposite as a reusable catalyst.

Multi-walled carbon nanotubes (MWNTs) were modified with carboxylic acid functional groups (MWCNTs-(COOH) ) prior to decoration with FeO nanoparticles. A further modification step by polyethyleneimine (PEI) resulted in FeO-MWCNTs@PEI which provided a suitable platform for coordination and reduction of silver ions to obtain an FeO-MWCNTs@PEI-Ag nanocomposite with highly dispersed Ag nanoparticles. The FeO-MWCNTs@PEI-Ag hybrid material was characterized by various techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), and was used as an efficient catalyst for chemoselective reduction of nitroaromatic and nitrile compounds to their corresponding amines in aqueous solution at ambient temperature. Nitrofurazone, a cytotoxic antibiotic, as a non-aromatic example was also reduced selectively at the nitro group without reduction of the other functionalities in the presence of FeO-MWCNTs@PEI-Ag. The catalyst was magnetically recoverable and maintained its activity for at least six cycles without considerable loss of efficiency.