Rate constants for reactions of iodine atoms in solution

✍ Scribed by Z. B. Alfassi; R. E. Huie; S. Marguet; E. Natarajan; P. Neta

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 443 KB
• Volume: 27
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550270208

✦ Synopsis

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 12-but do not react rapidly with 0 2 ( k I lo7 L mol-l s-l). Iodine atoms oxidize phenols to phenoxyl radicals, with rate constants that vary from 1.6 X lo7 L mol-l s-' for phenol to about 6 X lo9 L mol-' s-l 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 X 1O'O L mol-' s-'.

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 0 2 to give phenylperoxyl radicals, which react with phenols much more slowly than I atoms.