Magnetic MCM-41 nanoparticles as a support for the immobilization of a palladium organometallic catalyst and its application in C–C coupling reactions

Abstract

In this study, the surface of magnetic MCM-41 nanoparticles (MCM-41/Fe₃O₄) was modified by 3-aminopropyltriethoxysilane (APTES) and further, 1-methyl imidazole was anchored on their surface using cyanuric chloride as a linker. Then, Pd²⁺ ions were immobilized on the surface of the modified MCM-41/Fe₃O₄ (Pd-imi-CC@MCM-41/Fe₃O₄), and its application was studied as a magnetically recyclable nanocatalyst in carbon–carbon coupling reactions between a wide range of aryl halides and butyl acrylate, methyl acrylate, acrylonitrile, phenylboronic acid, or 3,4-difluorophenylboronic acid under the conditions of a phosphine-free ligand and an air atmosphere. This catalyst has the advantages of both the Fe₃O₄ nanoparticles and mesoporous MCM-41. The structure of the catalyst was characterized via TEM, SEM, EDS, WDX, N₂ adsorption–desorption isotherm, XRD, TGA, FT-IR, and AAS. Also, the recovered catalyst was characterized via SEM, AAS and FT-IR. All the products from the carbon–carbon coupling reaction were obtained with excellent yields and high TON and TOF values, which indicate the high efficiency and activity of this catalyst. The selectivity of this catalyst was studied with various aryl halides bearing different functional groups. Furthermore, the heterogeneity and stability of Pd-imi-CC@MCM-41/Fe₃O₄ was studied via AAS, and leaching and poisoning tests. According to the results, this heterogeneous catalyst can be reused several times.