Heterogenization of homogeneous NHC-Pd-pyridine catalysts and investigation of their catalytic activities in Suzuki-Miyaura coupling reactions

Abstract

New generation, novel, environmentally safe polymeric heterogeneous catalysts which included catalytically active NHC-Pd-pyridine complexes were prepared by radical polymerization of NHC-Pd-pyridine complexes with Acrylamide (AAm) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) monomers in the presence of N,N′-methylenebisacrylamide (MBA) crosslinker. Structural characterization of NHC-Pd-pyridine complexes was conducted by using NMR, FT-IR while the structural characterization of crosslinked polymeric catalyst systems was made by using FT-IR, SEM, SEM-EDX, TEM and TGA analysis techniques. The synthesized polymer-based NHC-Pd-pyridine catalysts showed good catalytic activity for Suzuki reaction of aryl bromides with phenylboronic acid in aqueous media. They exhibited good stability and they could be reused at least five times without remarkable loss of catalytic activity.