Resin-immobilized palladium nanoparticle catalysts for Suzuki-Miyaura cross-coupling reaction in aqueous media

Abstract

Macroporous ion-exchange resins were used to immobilize palladium (Pd) metal in order to produce nanoparticle catalysts. The complexation of palladium acetate and the following reduction with sodium borohydride to Pd nanoparticles was carried out on two macroporous ion-exchange resins: (1) a Dowex Marathon anion free weak base including a styrene-divinylbenzene polymer matrix and polyamine active groups, and (2) a Dowex M4195 anion exchange resin, a chelating type of resin having styrene-divinylbenzene polymer matrix with bispicolylamine active groups. Pd loading was quantified by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Scanning electron microscopy/energy-dispersive X-ray spectrometry (SEM/EDX) and transmission electron microscopy (TEM) of the catalyst were obtained for further characterization. Pd nanoparticles immobilized on a macroporous Dowex Marathon ion exchange resin exhibited excellent catalytic activity for the Suzuki-Miyaura reaction of bromobenzene with phenylboronic acid and thus it was further tested on various aryl bromides and aryl boronic acid derivatives using water as a solvent and either KOH or K2CO3 as a base at 100 degrees C. This protocol offers an environmentally benign alternative to several existing methods for the Suzuki-Miyaura reaction. Furthermore, the catalyst can be recycled without significant loss of its catalytic activity.