ARYLPEROXYL RADICALS, FORMATION, ABSORPTION-SPECTRA, AND REACTIVITY IN AQUEOUS ALCOHOL-SOLUTIONS

Aryl radicals (phenyl, 4-biphenylyl, 2-naphthyl, 1-naphthyl, and 9-phenanthryl) were produced by the reaction of the corresponding aryl bromide with solvated electrons and reacted rapidly with oxygen to produce the arylperoxyl radicals. These radicals exhibit optical absorptions in the visible range, with lambda(max) at 470, 550, 575, 650, and 700 nm, respectively. Arylperoxyl radicals react with 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonate ion) (ABTS), chlorpromazine, and 6-hydroxy-2,5,7,8-tetamethylchroman-2-carboxylic acid (Trolox C) by one-electron oxidation. The rate constants k for these reactions, determined from the rate of formation of the one-electron oxidation products as a function bf substrate concentration, vary between 4 x 10(6) and 2 x 10(9) L mol(-1) s(-1) and increase in the order phenyl-, 4-biphenylyl-, 2-naphthyl-, 1-naphthyl-, and 9-phenanthrylperoxyl, the same order as the absorption peaks of these radicals. Good correlation was found between log k and the energy of the absorption peak.