Selective oxidation of carbohydrates by 4-AcNH-TEMPO/peracid systems

Starch, amylopectin, inulin, pullulan and methyl α-d-glucopyranoside (Me α-Glcp) were oxidised by 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl (4-AcNH-TEMPO) as the mediator and peracetic acid or monoperoxysulfate (Oxone®) as the regenerating oxidant. The conversion of primary alcohol groups to the corresponding carboxyl groups proceeded with high yield and selectivity, provided that sodium bromide was added as co-catalyst. ss molecular distributions of the oxidised polysaccharides indicated that no major depolymerisation occurred during oxidation. Oxone appeared to be the most efficient oxidant as the reaction rate was 25 times higher than that of peracetic acid in the oxidation of Me α-Glcp. On the other hand, oxone produces a larger amount of waste as by-product than peracetic acid.