Product distribution in the Cl‐initiated photooxidation of CF 3 C(O)OCH 2 CF 3

The product distribution and the mechanism of the reaction of Cl atoms with 2 , 2 , 2 ‐trifluoroethyl 2 , 2 , 2 ‐trifluoroacetate (TFETFA; CF 3 C(O)OCH 2 CF 3 ) were investigated using a 1080 L environmental chamber with in situ Fourier transform infrared (FTIR) spectroscopy detection. The experiments were performed at (296 ± 2) K and atmospheric pressure (760 ± 10) Torr of synthetic air free of NO x . A yield of (45 ± 3)% was obtained for the CF 3 C(O)OC(O)CF 3 formation. CF 2 O and CO were produced with estimated yields of 35 and 28%, respectively. No trifluoroacetic acid (TFA; CF 3 C(O)OH) was observed. The yields determined are rationalized in terms of the competitive reaction channels for the fluoroalcoxy radicals formed in the H‐abstraction process: (a) reaction with O 2 , (b) CC, CO, CH decomposition, and (c) a possible α ‐ester rearrangement pathway. The negligible importance of the α ‐ester channel, to produce TFA, was explained by the reduction of the stability of the five‐membered transition state of the α ‐ester rearrangement. Atmospheric implications, particularly regarding the fluorocarboxylic acid formation, are discussed. Copyright © 2010 John Wiley & Sons, Ltd.