Atmospheric Chemistry of n-C x F 2x+1 CHO (x ) 1, 3, 4): Reaction with Cl Atoms, OH Radicals and IR Spectra of C x F 2x+1 C(O)O 2 NO 2 M. P. Sulbaek Andersen and O. J. Nielsen Department of Chemistry, UniVersity of Copenhagen, UniVersitetsparken 5, DK-2100 Copenhagen, Denmark M. D. Hurley, J. C. Ball, and T. J. Wallington* Ford Motor Company, P. O. Box 2053, Dearborn, Michigan 48121-2053 J. E. Stevens Department of Chemistry and Biochemistry, UniVersity of Detroit Mercy, 4001 West McNichols Road, P. O. Box 19900, Detroit, Michigan 48219-0900 J. W. Martin, D. A. Ellis, and S. A. Mabury Department of Chemistry, 80 St. George Street, UniVersity of Toronto, Toronto, Ontario, Canada M5S 3H6 ReceiVed: January 23, 2004; In Final Form: March 15, 2004 Smog chamber/FTIR techniques were used to measure (Cl + n-C x F 2x+1 CHO, x ) 1, 3, 4) ) (2.1 ( 0.5) × 10 -12 and k(OH + n-C x F 2x+1 CHO, x ) 1, 3, 4) ) (6.5 ( 1.2) × 10 -13 cm 3 molecule -1 s -1 in 700 Torr of N 2 , or air, at 296 ( 2 K. Cl-initiated oxidation of n-C x F 2x+1 CHO in the presence of NO in air diluent gave COF 2 in molar yields of 91 ( 11%, x ) 1; 273 ( 36%, x ) 3; and 371 ( 44%, x ) 4. Small quantities (molar yields e 3%) of CF 3 ONO 2 and n-C x F 2x+1 C(O)O 2 NO 2 were also observed. IR spectra of n-C x F 2x+1 C(O)O 2 NO 2 (x ) 1, 3, 4) are reported. Results are discussed with respect to the atmospheric degradation of fluorinated aldehydes, C x F 2x+1 CHO. 1. Introduction Concerns regarding the environmental impact of chlorofluo- rocarbon (CFC) release into the atmosphere have led to the replacement of CFCs in industrial processes and consumer products. Hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) are two classes of compounds that have gained widespread use as CFC substitutes. Polyfluorinated alcohols are currently used in a variety of industrial products (paints, coatings, polymers, adhesives, waxes, polishes, electronic materials, and caulks 1 ). Perfluorinated aldehydes are formed during the atmospheric oxidation of HFCs, HCFCs, and fluorinated alcohols. 2 Long-chain perfluoroalkyl carboxylic acids (PFCAs, C x F 2x+1 - COOH, where x ) 6-12) have been observed recently in fish 3,4 and mammals 5 in a variety of locations around the world. PFCAs are not generally used directly in consumer or industrial materials, other than in aqueous film forming foams or as polymerization aids in fluoropolymer manufacture. 6 Thermolysis of fluoropolymers produces PFCAs; however, the magnitude of this source appears insufficient to account for the observed global environmental burden of these compounds. 7 The PFCAs observed in the environment are presumably the degradation products of precursor chemicals. However, the identity of the precursors and mechanism by which they are converted into PFCAs are unknown at the present time. Perfluorinated aldehydes of the general formula C x F 2x+1 CHO have a molecular formula that is similar to that of perfluoroalkyl carboxylic acids. Atmospheric oxidation of perfluorinated aldehydes offers a possible route to the formation of PFCAs. Unfortunately, there are few available data upon which to make a quantitative assessment of the contribution made by atmo- spheric oxidation of perfluorinated aldehydes to the observed budget of PFCAs. To remedy this situation, we have reported the results of an investigation into the atmospheric chemistry of C 2 F 5 CHO. 8,9 To expand upon this work, a study of the atmospheric chemistry of CF 3 CHO, n-C 3 F 7 CHO, and n-C 4 F 9 - CHO was performed. Studies of fluorinated alcohols 10 and acids 11 suggest that n-C 3 F 7 CHO and n-C 4 F 9 CHO will serve as useful models with which to understand the degradation mechanism of long chain perfluoroaldehydes. Straight chain isomers n-C 3 F 7 CHO and n-C 4 F 9 CHO were studied in the present work. For simplicity, we will refer to these species as C 3 F 7 - CHO and C 4 F 9 CHO in the rest of this article. We have used smog chamber FTIR techniques to study the kinetics of reactions of Cl atoms and OH radicals with C x F 2x+1 - CHO (x ) 1, 3, 4) and oxidation products of the Cl-initiated oxidation of C x F 2x+1 CHO in the presence of NO x . Quantum mechanical calculations were employed to locate stable ground- state geometries for CH 3 C(O)OONO 2 and C x F 2x+1 C(O)OONO 2 (x ) 1-4) and to calculate IR spectra for these molecules. Results are discussed with respect to the atmospheric chemistry and environmental impact of fluorinated organic compounds. 2. Experimental Section 2.1. Kinetic and Mechanistic Experiments. The apparatus and experimental techniques used in this work have been described elsewhere. 12,13 Experiments were performed in a 140-L Pyrex reactor interfaced to a Mattson Sirus 100 FTIR spectrometer. The reactor was surrounded by 22 fluorescent * Corresponding author. E-mail: twalling@ford.com. 5189 J. Phys. Chem. A 2004, 108, 5189-5196 10.1021/jp0496598 CCC: $27.50 © 2004 American Chemical Society Published on Web 05/26/2004