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

Aryl radicals (phenyl, 4-biphenylyl, 2-naphthyl, 1-naphthyl, and 9-phe nanthryl) were produced by the reaction of the corresponding aryl brom ide 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-ethyl benzothiazoline-6-sulfonate ion) (ABTS), chlorpromazine, and 6-hydroxy -2,5,7,8-tetamethylchroman-2-carboxylic acid (Trolox C) by one-electro n oxidation. The rate constants k for these reactions, determined from the rate of formation of the one-electron oxidation products as a fun ction 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-n aphthyl-, 1-naphthyl-, and 9-phenanthrylperoxyl, the same order as the absorption peaks of these radicals. Good correlation was found betwee n log k and the energy of the absorption peak.