Catalytic Oxidation of Glucose with Hydrogen Peroxide and Colloidal Gold as Pseudo-Homogenous Catalyst: A Combined Experimental and Theoretical Investigation

Abstract

Gold nanoparticles have been proved to act as oxidation catalyst for glucose oxidation, offering a “chemical” synthetic route to gluconic acid and gluconates - nowadays commercially produced by an enzyme catalyzed oxidation. Our investigations of the gold catalyzed oxidation route showed that gold nanoparticles produced by a modified Turkevich method have a high activity for this pseudo-homogenous catalytic reaction. Under mild reaction conditions, glucose could be oxidized in good yields (~70%) and the resulting gluconate could be isolated by column chromatography and precipitation as calcium salt. The catalytic oxidation reaction was found to follow the first-order kinetic with a rate constant of 4.95 h-1, in good agreement with previous finding. The underlying reaction mechanism is discussed, assuming that the formation of a gold-glucose cluster intermediate is a key catalytic step. Several structures of the gold-glucose intermediates were examined using density functional theory methods. The molecular behavior of glucose adsorption in gold colloid solution is present.