Fe3O4-chitosan immobilized Cu(II) Schiff base catalyst for the microwave-assisted amination of aryl halides in water

This work represents the synthesis, characterization, and application of a magnetically separable (Fe3O4@CS@AF@Cu) catalyst for the C-N coupling reaction towards arylation of amines. The catalyst is synthesized by modifying the surface of Fe3O4-chitosan with acetyl-2-furan (AF) via the formation of Schiff base and then, generating a Cu(II) complex on the functionalized surface. State-of-art characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), X-ray diffractometer (XRD), x-ray photoelectron spec-troscopy (XPS) and inductively coupled plasma-optical emission (ICP-OES) spectrometry have been used to verify the structure of the catalyst. Under microwave irradiation, the Ullmann C-N coupling reactions using various aryl halides and amines demonstrate exceptional catalytic performance with a minimal catalyst loading of 0.63 mol% of Cu. Furthermore, the catalyst has been recycled 5 times with 96% efficiency for the amination of 1-bromo-4-nitrobenzene with piperidine under the investigated conditions. Overall, this study provides a practical approach to the synthesis of an effective heterogeneous catalyst for the C-N coupling reaction, which can be used in pharmaceuticals, bulk, and fine chemical industries. (c) 2023 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).