Construction of Fe3O4@SiO2-ABA-Amide/BTH-Cu(II) nanocomposite as a reusable magnetic catalyst for reduction of nitroarenes and nitriles to amines

Abstract

A novel nanomagnetic recoverable catalyst has been developed from a copper (II) complex supported on the surface of Fe₃O₄ nanoparticles. In the initial step, Fe₃O₄@SiO₂ was functionalized with 4-aminobenzoic acid, chosen for its safety, cost-effectiveness, and environmentally friendly properties as an amine source. This was then reacted with benzo[d]thiazole-2-carbonyl chloride to immobilize the desired benzothiazole structure, serving as a ligand for Cu(II). The resulting catalyst, Fe₃O₄@SiO₂-ABA-Amide/BTH-Cu(II), was successfully synthesized and thoroughly characterized using a range of spectroscopic techniques, including FT-IR, SEM, TEM, EDX, TGA, XRD, VSM, and ICP-OES. This nanomagnetic copper catalyst exhibits high catalytic efficiency in the reduction of a broad library of nitro compounds to the desired amines. Using this eco-friendly catalytic system, a diverse range of aliphatic and aromatic amines was synthesized with good to excellent yields in a suitable time range. The Fe₃O₄@SiO₂-ABA-Amide/BTH-Cu(II) catalyst can be easily recovered using magnetic attraction and retains its effectiveness after being washed with an organic solvent and water. It demonstrated consistent performance across at least eight consecutive runs, highlighting its durability and efficiency. The ease of fabrication and straightforward process of magnetic separation are pivotal advantages of the current catalyst, making it highly effective for large-scale applications. One of its remarkable features is its excellent recyclability, which allows for up to eight repeated uses without significant loss in performance. Additionally, the catalyst demonstrates impressive yields of amine products, coupled with a high loading capacity of palladium onto the modified surface of magnetic nanoparticles. These characteristics collectively highlight the catalyst’s efficiency and practicality in various industrial applications.

Graphical abstract