Conversion of dehydroascorbic acid to a branched hexaric acid in neutral and alkaline aqueous solution

Dehydroascorbic acid is shown to be converted to 2-(threo-1,2,3-trihydroxypropyl)tartronic acid in aqueous alkaline solutions. The structure of the acid was determined by mass spectrometry of its acyclic Me3Si derivative. Mass spectrometric and chromatographic data are compared with those of related compounds. The acid is formed by a benzilic acid rearrangement of the intermediate 2,3-hexodiulosonic acid. The rate of formation at 38\ub0C was studied quantitatively by glc. It increases at increased alkalinity but is significant even at physiological pH. The presence of oxygen does not substantially influence the reaction