Immobilized NNN Pd-complex on magnetic nanoparticles: efficient and reusable catalyst for Heck and Sonogashira coupling reactions

Abstract

A highly efficient and easily recyclable magnetic nanoparticle supported palladium catalyst was developed and applied in the Heck and Sonogashira reactions in order to show its catalytic applicability in Pd-catalyzed C–C coupling protocols. The catalyst was prepared using a simple chemical process. First, the prepared Fe₃O₄@SiO₂ nanoparticles were reacted with (3-chloropropyl)-trimethoxysilane (3-CPTMS) in order to synthesis chloro-functionalized magnetic nanoparticles (CPS-MNPs). The substitution reaction of synthetic NNN ligand with CPS-MNPs yields the production of CPS-MNPs–NNN ligand. Finally, immobilization of palladium species on CPS-MNPs–NNN ligand surface afforded CPS-MNPs–NNN–Pd catalyst. The structure and morphology of the prepared nanocatalyst was characterized using various methods such as SEM, TEM, XPS, EDX, CHN, ICP, XRD, FT-IR and VSM techniques. The TEM images show that the sizes of the palladium catalyst are in the range of 8–15 nm. The Heck and Sonogashira coupling reactions were performed in the presence of a catalytic amount of this catalyst system (0.5 mol%) and good yields of products were obtained. Due to the magnetic nature of the catalyst it can be separated from the reaction mixture easily by applying an external magnetic field. Heterogeneity tests affirmed that the catalytic activity stayed indefectible during multiple reaction cycles.