Supported Gold Nanoparticles as Efficient Catalysts in the Solventless Plasmon Mediated Oxidation of <i>sec</i>-Phenethyl and Benzyl Alcohol

Abstract

Surface plasmon excitation of supported gold nanoparticles in the presence of H₂O₂ leads to selective oxidation of <i>sec</i>-phenethyl and benzyl alcohols to the carbonyl products acetophenone and benzaldehyde, respectively, in the absence of additional solvents. Light-emitting diodes are compared with microwave irradiation as excitation sources. Hydrotalcite, ZnO, and Al₂O₃ have been chosen as the solid supports. The overall efficiency of the alcohol oxidation was found to be largely dependent on the nature of the support, with hydrotalcite-derived nanocomposites giving the highest conversions to product, yielding 90% acetophenone after 40 min of LED irradiation. The mechanism for plasmon-mediated alcohol oxidation is believed to involve a significant contribution from the support itself, with adsorption of the alcohol substrate and progression of the oxidation reaction being largely facilitated by the basicity of the support used