Atmospheric Chemistry of 4:2 Fluorotelomer Iodide (n-C4F9CH2CH2I): Kinetics and Products of Photolysis and Reaction with OH Radicals and Cl Atoms

Relative rate techniques were used to study the title reactions and determine rate constants of k(Cl+ C4F9CH2CH2I) = (1.25 +/- 0.15) x 10(-12) and k(OH + C4F9CH2CH2I) = (1.2 +/- 0.6) x 10(-12) cm(3) molecule(-1) S-1 in 700 Torr total pressure at 295 K. The fluorotelomer aldehyde (C4F9CH2CHO), perfluorinated aldehyde (C4F9CHO), fluorotelomer acid (C4F9CH2C(O)OH), fluorotelomer peracid (C4F9CH2C(O)OOH), and several perfluorocarboxylic acids were detected by in situ FUR spectroscopy and offline analysis as products of the chlorine atom initiated oxidation of C4F9CH2CH2I in air. The UV-visible spectra of C4F9CH2CH2I and C2H5Cl were recorded over the range of 200-400 nm. Photolysis of C4F9CH2CH2I gives C4F9CH2CHO as the major observed product. By assumption of a photolysis quantum yield of unity, it was calculated that the atmospheric lifetime of C4F9CH2CH2I is determined by photolysis and is a few days. A mechanism for the atmospheric oxidation of fluorotelorner iodides, (CxF2x+1CH2CH2I, where x = 2, 4, 6,...) is proposed. Atmospheric oxidation of fluorotelorner iodides is a potential source of perfluorocarboxylic acids.