Effect of fluorine substitution on the OH-radical-induced electron-transfer reaction in aqueous solutions of fluorinated alkyl iodides

The transient optical absorption bands formed at λ_max=340 and 435 nm, on reaction of ^√OH radicals in aerated acidic aqueous solutions of 1,1,1-trifluoro-2-iodoethane at low and high solute concentration, have been assigned to monomer and dimer radical cations, respectively. The deprotonation of the solute radical cations is the rate-determining 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°C. The dimer radical cation is a strong one-electron oxidant. Quantum chemical calculations and experimental results confirm that fluorine reduces the electron density at iodine and the ^√OH-radical-induced oxidation of fluoroiodoalkanes becomes a difficult process compared to iodoalkanes.