Magnetic bentonite decorated with Pd nanoparticles and cross‑linked polyvinyl pyridine as an efcient nanocatalyst for Suzuki coupling and 4‑Nitrophenol reduction reactions

Abstract

This study reports the preparation of a novel type of support based on magnetically recyclable bentonite functionalized with divinylbenzene-polyvinyl pyridine (PVP-DVB) for Pd (II) nanocatalyst by a simple cost-effective method. Firstly, the conventional co-precipitation method synthesized Fe3O4 nanoparticles (NPs) onto bentonite sheets. Then the prepared magnetic support surface was functionalized by divinylbenzene-polyvinyl pyridine (PVP-DVB) to create a cross-linked polymer with a high coordination ability with palladium. Repeated nitrogen units in the PVP-DVB polymer chain increase the number of Pd bonds and thus lead to higher performance of the nanocatalyst. Finally, the palladium NPs were simultaneously synthesized and immobilized under mild conditions. The synthesized nanocatalyst was characterized by several methods such as scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometer, inductively coupled plasma mass spectrometry and thermogravimetric analysis. The efficiency of synthesized heterogeneous nanocatalyst was investigated in Suzuki–Miyaura cross-coupling reactions between a range of aryl halides (X = Cl, Br, I) with phenylboronic acid and in the reduction of 4-nitrophenol (4-NP). Moreover, the synthesized nanocatalyst could be easily recovered and reused several times with an efficiency greater than 90%.