Highly dispersed palladium nanoparticles immobilized on mesoporous Iron oxide for Suzuki-Miyaura coupling in water using a cellulose additive

Traditionally, cross-coupling reactions were performed using soluble homogenous complexes such as palladium acetate and palladium chloride with various phosphine ligands. In this work, hydroxypropyl methylcellulose, an additive that readily forms hydrophobic pockets that act as nanoreactors in water, was used in Suzuki-Miyaura coupling reactions with a heterogeneous catalyst. Mesoporous Fe₂O₃ was synthesized using the sol-gel method and used as support to immobilize the palladium nanoparticles using the precipitation deposition method. The synthesized Pd-Fe₂O₃ was characterized accordingly with BET, p-XRD, TEM, SEM, and TGA techniques. Optimization studies were then performed to compare the effects of various solvents and bases using a model reaction in which benzyl bromide was coupled with phenylboronic acid. The hydroxypropyl methylcellulose/water solvent system resulted in a 100% conversion of halide, and the most suitable base, potassium carbonate resulted in 100% conversion. The Suzuki-Miyaura coupling reactions as investigated in this study were quite successful with appreciable yields of products and 100% selectivity. The Pd-Fe₂O₃ proved to be stable in water, easily recoverable and reusable.