TEMPO mediated oxidation of carbohydrates using electrochemical methods

The oxidation of some readily available carbohydrates was investigated in aqueous medium using a catalytic amount of 2,2,6,6-Tetramethyl-1-piperidinyl-oxy (TEMPO) as redox mediator. The regeneration of oxoammonium (active form) was electrochemically performed in alkaline medium at a glassy carbon anode and at controlled potential (0.5 V vs. AgCl/Ag). The primary alcohol groups of the carbohydrates without free aldehyde group, were selectively oxidized to the corresponding sodium uronate with high Faradaic yields. The presence of free aldehyde or hemiacetal groups leads to a decrease in selectivities towards uronic acids and increases the amount of by-products.