EFFECT OF FLUORINE SUBSTITUTION ON THE CENTER-DOT-OH-RADICAL-INDUCED ELECTRON-TRANSFER REACTION IN AQUEOUS-SOLUTIONS OF FLUORINATED ALKYL IODIDES

The transient optical absorption bands formed at lambda(max) = 340 and 435 nm, on reaction of .OH radicals in aerated acidic aqueous solutio ns of 1, 1, 1-trifluoro-2-iodoethane at low and high solute concentrat ion, have been assigned to monomer and dimer radical cations, respecti vely. The deprotonation of the solute radical cations is the rate-dete rmining step for the decay of the dimer radical cations. The stability constant for the dimer radical cation is determined to be 50 dm3 mol- 1 at 25-degrees-C. The dimer radical cation is a strong one-electron o xidant. Quantum chemical calculations and experimental results confirm that fluorine reduces the electron density at iodine and the .OH-radi cal-induced oxidation of fluoroiodoalkanes becomes a difficult process compared to iodoalkanes.