Development of a Reusable Magnetic Green SPE Electrode Based on Fe₃O₄@SiO₂-L-Proline-Coated Nickel Nanoparticles for Electro-Organic Buchwald–Hartwig Amination in NaCl Electrolyte

One of the major challenges in electro-synthesis reactions is the corrosion of electrode surfaces and catalysts, which can significantly affect their usability and lead to environmental concerns, increased production costs, and difficulties in scaling up processes. Addressing these challenges is crucial for enhancing the sustainability and efficiency of electro-synthesis. This paper presents the design and synthesis of an innovative magnetic electrode utilizing Fe₃O₄-SiO₂ modified with L-proline and coated with nickel (Ni) nanoparticles (NPs), specifically for the electro-organic Buchwald-Hartwig amination reactions. This electrode combines the magnetic properties of Fe₃O₄ with the catalytic potential of Ni NPs, further enhanced by the surface modification with L-proline to enhance catalytic efficiency and selectivity in C–N bond-forming reactions. The performance of the catalyst in the electro-amination reaction of chlorobenzene 1(a-c) and aniline 2(a-j) for the synthesis of diphenylamine 4(a-k) derivatives was evaluated under ambient temperature, using iPrOH as the solvent, for 2 h at a constant current of 15 mA. The reaction yielded good to excellent results, with a yield ranging from 89 to 98%. This approach offers a sustainable, cost-effective solution for electro-organic amination reactions, with potential applications in industrial-scale organic synthesis. The catalyst was successfully synthesized, and its structural properties were comprehensively analyzed using a range of techniques, including FT-IR, SEM, EDS, BET, TGA, CV, XPS, VSM, and EDX. Key parameters, including surface characteristics, surface area, morphology, and thermal stability, were thoroughly evaluated. The synthesized derivatives were further characterized using melting point determination, 1 H NMR, and CHN analyses.