OH radical reactions with ethanolamines: formation of reducing as well as oxidizing radicals

The reaction of OH radicals with ethanolamine, diethanolamine and triethanolamine was studied at pH values below and above the pK_a values of these compounds. The rate constants were found to be lower for the protonated amines than those for their neutral forms. The OH radical reaction led to the formation of both oxidizing as well as reducing species, as observed by their reactions with methyl viologen and ascorbic acid. The oxidizing species formed by OH radical reaction at the amine site was not found to react with the parent molecules and thereby no secondary yield of reducing species was obtained as in the case of glycine (except in the case of triethanolamine at pH 9.2).