On the interaction of glucose with ammonium molybdate (Hager-Gawalowsky test)

Glucose is an Analyte. Thus, several tests for its detection in urine have been developed. In the present communication the reaction route of the Hager-Gawalowsky test for glucose is provided. Each step is fully commented and the electron flow is also given. The test is based on the interaction of glucose with ammonium molybdate in neutral medium, a blue colour is produced on heating. The active hydrogen in glucose is removed by the inorganic anion, and the resulting enolate from an enediol reacts with the mono-anion just formed. A hydroxylate is eliminated via open-close of a Mo-O double bond. Hydrion switch forms a second enolate that produces a concerted mechanism affording 2-ketoglucose and molybdenum dioxide by a redox reaction.