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) × 10⁻¹² and k(OH + C₄F₉CH₂CH₂I) = (1.2 ± 0.6) × 10⁻¹² cm³ 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 FTIR 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 fluorotelomer iodides, (C_xF_2x+1CH₂CH₂I, where x = 2, 4, 6,...) is proposed. Atmospheric oxidation of fluorotelomer iodides is a potential source of perfluorocarboxylic acids.