Rate constants for reactions of iodine atoms in solution

Laser flash photolysis (at 248 or 308 nm) or aryl iodides in water or water/methanol solutions produces iodine atoms and phenyl radicals. Iodine atoms react rapidly with added I⁻ to form I₂⁻ but do not react rapidly with O₂ (k ⩽ 10⁷ L mol⁻¹ s⁻¹). Iodine atoms oxidize phenols to phenoxyl radicals, with rate constants that vary from 1.6 × 10⁷ L mol⁻¹ s⁻¹ for phenol to about 6 × 10⁹ L mol⁻¹ s⁻¹ for 4‐methoxyphenol and hydroquinone. Ascorbate and a Vitamin E analogue are also oxidized very rapidly. N‐Methylindole is oxidized by I atoms to its radical cation with a diffusion‐controlled rate constant, 1.9 × 10¹⁰ L mol⁻¹ s⁻¹. Iodine atoms also oxidize sulfite and ferrocyanide ions rapidly but do not add to double bonds. The phenyl radicals, produced along with the I atoms, react with O₂ to give phenylperoxyl radicals, which react with phenols much more slowly than I atoms. © 1995 John Wiley & Sons, Inc.