Immobilized palladium nanoparticles on a silica-starch substrate (PNP-SSS): as an efficient heterogeneous catalyst for Heck and copper-free Sonogashira reactions in water

This paper reports an efficient heterogeneous catalyst system based on the immobilization of Pd nanoparticles on a silica-starch substrate (PNP-SSS). The PNP-SSS is found as a highly effective recyclable catalyst in Heck and copper-free Sonogashira reactions. The silica-starch substrate (SSS) can stabilize the Pd nanoparticles effectively so that it can provide a platform and prevent the aggregation of nanoparticles and their separation from the substrate surface. It also provides suitable catalytic sites for reactions in aqueous media. The Heck and copper-free Sonogashira reactions are performed in the presence of a small amount of this catalyst in water as a green solvent. The catalyst can be reused more than six times with almost consistent efficiency and can be recovered by simple filtration.