Generation of Rare Sugars by Electrochemical Oxidation of <scp>d</scp>-Glucose Using Boron-Doped Diamond Electrode

The electrochemical oxidation of biomass for the production of value-added chemicals represents a promising approach in the field of sustainable chemistry. In this study, we investigated the electrochemical conversion of d-glucose, a biomass-derived compound, using boron-doped diamond (BDD) electrodes under constant applied current (10 mA) or potentials (1.5-3.0 V vs Ag/AgCl). The reaction products were analyzed using high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS) measurements, employing both <i>p</i>-aminobenzoic acid ethyl ester (ABEE) and l-tryptophan amide labeling methods to enable characterization. The results demonstrated that the BDD electrodes achieved 95.9% d-glucose degradation and successfully generated various rare sugars, including d-arabinose (0.126 mmol/L), d-erythrose (0.0544 mmol/L), d-glyceraldehyde, and l-glyceraldehyde (combined 0.148 mmol/L). Under identical conditions, Pt electrodes as a control showed only 10.2% d-glucose degradation with significantly lower rare sugar yields. The applied potential significantly influenced the product distribution, with optimal rare sugar production observed at 2.5 V vs Ag/AgCl, reflecting a balance between glucose oxidation and product degradation. Mechanistic studies suggest that the formation of rare sugars involves a series of oxidation and decarboxylation reactions, facilitated by electrochemically generated active species. The superior performance of the BDD electrodes is attributed to their wide potential window, efficient generation of oxidizing species, and unique surface characteristics. This research provides new insights into the electrochemical transformation of biomass-derived compounds and demonstrates the potential for sustainable production of high-value rare sugars, opening avenues for applications in food science, pharmaceuticals, and green chemistry.