CuII immobilized on aminated Fe3O4@ cellulose nanofibers (Fe3O4@ cellulose nanofibers -NH2-CuII NPs): a novel, bio-based and magnetic nanocatalyst for the synthesis of benzimidazole derivatives

From the point of view of green chemistry magnetically recoverable catalysts have appeared as a powerful and persuasive option, due to their ability like excellent catalytic performance and easy separation and recovery from the reaction mixture [1]. Aggregation/ oxidation of metal particles and reduction in catalytic activity which are kinetic problems often caused by highly active surface atoms can be solved by a well-chosen stabilizer [2]. Such a stabilizer is able to control the size of particles, improve the chemical stability, shape the magnetic features of the hybrid materials, avoid the agglomeration and also obtain the catalyst aim. cellulose nanofibers (CNFs) is of excellent interest due to properties such as nontoxicity, earth abundance, biodegradability, broad chemical-modifying capacity and fine chemical stability [3]. Synthesis privileged of benzimidazoles through an economical and environmentally friendly method is always desirable because benzimidazoles and its derivatives have received extensive attention in medicinal chemistry and show a wide spectrum of pharmacological activities [4]. In this study we report the synthesis of a novel heterogeneous Cu nano-particles bio-supported based magnetic nanomaterials catalyst (Fe3O4@ CNPs- NH2-CuII NPs) and its identification by various techniques like FTIR, TGA, SEM, TEM, EDX, ICP-AES and VSM. The applicability of the constructed heterogeneous nanocatalyst was explored in the synthesis of benzimidazoles through the cyclization reaction of 2-amino anilines with benzaldehyde derivatives using O2 as an oxidant in ethanol as a green solvent at 70 °C. The catalyst could be easily separated by an external magnet and reused for at least five times without any appreciable loss of its catalytic reactivity