An efficient Heck reaction in water catalyzed by palladium nanoparticles immobilized on imidazolium–styrene copolymers

Imidazolium–styrene copolymers were prepared by copolymerization of 1-vinyl-3-butylimidazolium based ionic liquids ([VBIm]X, X = Cl−, BF4-, and PF6-) with styrene, which were used as polymeric supports to immobilize Pd(OAc)2 using a method of alcohol reduction. It was demonstrated that Pd existed in the form of Pd nanoparticles on these imidazolium–styrene copolymers. Using the [VBIm]Cl–styrene copolymer as a support, Pd nanoparticles of less than 6 nm were formed, which was particular interesting, as usually only a Pd carbene complex was formed when Pd(OAc)2 was treated with 1,3-dialkyimidazolium ionic liquids containing a halide anion. The copolymer-supported Pd catalysts were found to be efficient and reusable catalysts for the Heck reaction in water in the absence of a phosphine ligand and phase-transfer catalyst.