Alkaline degradation of glucose: effect of initial concentration of reactants

The alkaline degradation of d-glucose in aqueous Ca(OH)2 at 100°C resulted in a complex mixture of more than 50 compounds, including parasaccharinic acid, that were identified by GLC-MS. The effect of reactant concentrations on the alkaline reaction products was studied by varying the concentration of glucose (1.8–100%, w/w). Under the different reactant concentrations the same saccharinic acids were produced, which is also true when no water was added to the reaction mixture. The increase of glucose concentration favored the formation of C6 acids (2-C-methylpentonic, hexametasaccharinic, and isosaccharinic acids) and decreased the formation of < C6 acids (glycolic, lactic, glyceric, 2-C-methylglyceric, deoxytetronic, and deoxypentonic acids). The identification of parasaccharinic acid provides further support for the existence of the glucose-3,4-enediol.