Polymer-coated palladium nanoparticle catalysts for Suzuki coupling reactions

• We report the use of polymer-coated palladium nanoparticles in catalysis.
• The effect of polymer structure on the catalytic activity was established.
• A low concentration of stabilizer was used, compared to previous studies.
• Yields of Suzuki couplings correlated with rate constants of a model reaction.
• Macromolecules with pendant pyridyl moieties are unsuitable capping agents.

A set of seven different palladium nanoparticle (PdNP) systems stabilized by small amounts (1.0 mg/mL) of structurally related macromolecular capping agents were comparatively tested as catalyst in p-nitrophenol (Nip) reduction and Suzuki cross-coupling reactions. The observed rate constants (kobs) for Nip reduction were in the range of 0.052–3.120 × 10−2 s−1, and the variation reflected the effects of polymer chain conformation, ionic strength and palladium–polymer complex coordination. Macromolecules featuring pendant pyridyl moieties or inverse temperature-dependent solubility were found to be unsuitable capping agents for PdNPs catalysts, despite being active. The catalytic activity in Suzuki cross-coupling reactions followed the same behavior; the most active particles in the Nip reaction also mediated the cross-coupling reaction providing the expected products in quantitative yields under relatively mild conditions after only 4 h at 50 °C. Experiments involving the successive addition of reactants and catalyst recovery/re-use indicated that the recycling potential was comparable to those of the standards used in this field.

Figure optionsDownload high-quality image (42 K)Download as PowerPoint slide