Palladium nanoparticles decorated on a novel polyazomethine as a highly productive and recyclable catalyst for Suzuki coupling reactions and 4-nitrophenol reduction

This report displays the procedure in preparation of fast, highly productive, reusable, and easily retrievable Pd nanoparticles (NPs) as a heterogeneous catalyst (Pd NPs@P(3-MPAP)) immobilized on a novel polyazomethine with phenol group, Poly(3-methyl-4-((pyridin-2-ylmethylene) amino) phenol) (P(3-MPAP)), and the investigation of its catalytic efficiency in fabrication of several biaryl compounds by Suzuki coupling reactions and reduction of 4-nitrophenol to 4-aminophenol. The structures of the synthesized monomer, polymer support material and nanocatalyst were identified by UV-Vis, FT-IR, H-1 NMR, TGA, XRD, SEM and EDS methods. The catalytic activity of Pd NPs@P(3-MPAP) catalyst in the synthesis of various biaryls by Suzuki coupling reactions was explored using microwave irradiation, which is rapid, easy, solventless and environmentally friendly method. The nanocatalyst presented outstanding advantageous methodology containing easy work-up with high reaction yield (99%) at very short reaction time (5 min) in solventless media using very low catalyst loading (0.007 mol%) in the synthesis of biaryls. Additionally, the harmful 4-nitrophenol was completely reduced to industrially useful 4-aminophenol in the presence of Pd NPs@P(3-MPAP) with low catalyst amount (1 mg), at very short reaction time (60s) without any toxic solvent (in water) at room temperature. Additionally, reproducibility test results for both catalytic reactions show that the highly productive nanocatalyst was easily retrievable and reusable for six and five sequential cycles, respectively, for Suzuki coupling reactions and reduction of 4-NP without any notable loss in its catalytic activity. (C) 2019 Elsevier B.V. All rights reserved.