Specific Selectivity of Au-Catalyzed Oxidation of Glycerol and Other C3-Polyols in Water without the Presence of a Base

A big challenge in upgrading bio-oxygenate platform molecules is to develop catalysts for the selective oxidation of a nonterminal HO-bonded carbon atom in polyols. We report herein the first finding of a specific selectivity of oxide-supported nano-Au catalysts for dihydroxyacetone (DHA) production in glycerol oxidation in water without NaOH. Though the support nature (Al 2 O 3, TiO 2, ZrO 2, NiO, and CuO) significantly affects the Au activity, a highly active Au/CuO catalyst offering DHA yields up to 80% at 40–50 °C has been identified. Rich data are provided to clarify that DHA is the only primary product of glycerol oxidation. This propensity of nano-Au for oxidizing the HO-bonded secondary (central) carbon is further verified by comparing the oxidation of propanediols and propanols. Molecular insight into the reactions is given on the basis of the kinetic isotopic effect study of deuterium on the oxidation of 2-propanol, uncovering an unanticipated chemistry of Au catalysis.