Solvated electron reactions in water--alcohol solutions

Rate constants for solvated electron reactions with oxygen, hydrogen peroxide, benzoquinone, nitrobenzene, and iodine in aqueous binary solutions of methanol and ethanol were determined by pulse radiolysis. The measured rate constants were used in conjunction with known diffusion coefficients to calculate reaction radii from the Debye--Smoluchowski equation. The calculated radii for the electron--oxygen reaction are found to be independent of the water--alcohol ratio for both solvent systems. The radii for the electron reaction with hydrogen peroxide show a similar behavior. For electron reactions with nitrobenzene, benzoquinone, iodine, and carbon tetrachloride the reaction radii increase with the increasing alcohol content in the solution, while the sums of diffusion coefficients of the reactants decrease. A correction for tunneling is suggested to explain the large reaction radii (6 to 15 A) for solvated electron reactions with several effective solutes. 1 figure; 3 tables; 24 references