Atmospheric Chemistry of CH 3 OCF 2 CHF 2 .

Fourier transform infrared spectroscopy has been used to follow the reaction of CH 3 OCF 2 CHF 2 with either Cl or OH radicals within a photoreactor. Rate constants of k (OH + CH 3 OCF 2 CHF 2 ) = (2.25 ± 0.60) × 10 -14 cm 3 molecule -1 s -1 and k (Cl + CH 3 OCF 2 CHF 2 ) = (2.50 ± 0.39) × 10 -13 cm 3 molecule -1 s -1 were determined at 296 ± 2 K. Theoretical and experimental investigation of the Cl + CH 3 OCF 2 CHF 2 reaction identified the formation of two main products, HC(O)OCF 2 CHF 2 and COF 2 . Chlorine (and OH) radicals react with CH 3 OCF 2 CHF 2 by H-abstraction from either the -CH 3 or -CHF 2 site. Abstraction from the -CH 3 site was determined to constitute at least 60%, as determined from the formation of the primary product, HC(O)OCF 2 CHF 2 , which can only form from this abstraction site. At longer reaction times, HC(O)OCF 2 CHF 2 further reacts and the yield of COF 2 approaches two, the maximum possible with the number of F atoms in the reactant. The atmospheric lifetime of CH 3 OCF 2 CHF 2 with OH radicals was determined to be 1.4 years. The global warming potentials over 20-, 100-, and 500-year time horizons were estimated to be 325, 88, and 25, respectively.