Abstract
Catalytic hydrogenation of sodium D-xylo-5-hexulosonate (sodium 5-keto-D-gluconate) and its acid has been investigated on nickel, ruthenium, rhodium and palladium with or without boron-modification. It was found that nickel and palladium catalysts produce more L-idonate than D-gluconate especially when the metals are prepared by treating their salts with sodium borohydride. Two adsorbed models for the substrate were presented to account for the observed hydrogenation selectivity, and the role of boron at the surface was discussed in terms of complexing with two hydroxyls of L-idonate.
