Facile and surfactant-free synthesis of Pd nanoparticles by the extract of the fruits of Piper longum and their catalytic performance for the Sonogashira coupling reaction in water under ligand- and copper-free conditions

This work reports a facile synthesis of palladium nanoparticles (Pd NPs) by the extract of the fruits of Piper longum without any stabilizer or surfactant. The Pd NPs were found to be effective catalysts for the ligand-, amine-and copper-free Sonogashira coupling reaction under aerobic conditions. The Pd NPs were characterized with UV-vis, FT-IR and TEM methods. This method has the advantages of high yields, simple methodology, and elimination of ligands, copper, organic solvents and homogeneous catalysts and easy work up. Water is used as the only solvent for the coupling reaction. More importantly, the catalyst was recovered and recycled by a simple decantation of the reaction solution and used for five consecutive trials without significant loss of its reactivity.