Water soluble polymer-surfactant complexes-stabilized Pd(0) nanocatalysts: Characterization and structure-activity relationships in biphasic hydrogenation of alkenes and α,β-unsaturated ketones

A suitable approach to stabilize palladium nanoparticles in water as a green reaction medium for catalytic hydrogenation reactions is described. Supramolecular self-assemblies, obtained through the mixture of modified polyethyleneimines as amphiphilic polymers and water-soluble ammonium salts as surfactants, were used as efficient protective agents in the synthesis of Pd(0) nanospecies. The size and dispersion of the nanoparticles prepared with these original self-assemblies were characterized by TEM, SAXS and DLS techniques. The performances of the catalysts according to the polymer-surfactant mixtures were investigated in the hydrogenation of alkenes and alpha,beta-unsaturated ketones in pure biphasic water/substrate medium, under mild conditions (room temperature and I bar H-2). The nanocatalysts showed efficient catalytic activities and selectivity towards C=C bonds. From investigations, the polymer-surfactant complexes act as cooperative protective agents and a pertinent structure-activity relationship was proposed based on the zeta-potential values and the catalytic activity of the resulting colloids. (C) 2016 Elsevier Inc. All rights reserved.