Reaction of Dihydroxymethyl Radical with Molecular Oxygen in Aqueous Solution

Abstract

Abstract Dihydroxymethyl radical (1) was found to react with oxygen diffusion controlled (k = 4.5 x 10 9 M -1 s -1 ). The final products of the reaction are formic acid and 1/2 hydrogen peroxide. The precursor of H 2 O 2 was shown to be O 2 ·- which is formed with G(O 2 ·- ) = 6.3 (a value which includes the O 2 ·- formed by H atoms and oxygen (G(H) = 0.55)). If it is assumed that dihydroxymethylperoxyl radicals are formed as intermediates the rate constant of O 2 ·- formation must be ≥ 10 6 s -1 . A bimolecular reaction of two dihydroxy-methylperoxyl radicals forming tetroxides does not occur at the dose rates used. The rate constants for the establishment of the equilibrium have been determined at pH 5.7 and 19 °C to be k 3 =1.9x 10 -2 M -1 s -1 and k -3 = 1.5 X 10 -6 M -1 s -1 in aqueous solution.