Solid-Phase Catalytic Reactions of Tritium with Carbohydrates: 4. Mechanism of Isomerization of D-Glucose in the Course of Solid-Phase Catalytic Hydrogenation with Tritium

The influence exerted on solid-phase catalytic hydrogenation (SCH) of D-glucose with tritium by the temperature varied in the range 90-140 degrees C, platinum group catalysts, solid phase composition, reaction time, and surface area of the support was examined. Fructose and mannose were identified in the reaction products along with labeled glucose. The mechanism of the isomerization of glucose into fructose and mannose in the solid phase under the action of hydrogen spillover was suggested. The glucose isomerization occurs by a complex mechanism analogous to acid-catalyzed keto-enol tautomerization of epimeric sugars in solution, and the active species in SCH of D-glucose with tritium is spillover hydrogen in the form of proton.