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An Investigation of the Reactivity of OH with Fluoroethanes: CH3CH2F (HFC-161),...

Kozlov, S. N., V. L. Orkin, and M. J. Kurylo (2003), An Investigation of the Reactivity of OH with Fluoroethanes: CH3CH2F (HFC-161), CH2FCH2F (HFC-152), and CH3CHF2 (HFC-152a), J. Phys. Chem. A, 107, 2239-2246, doi:10.1021/jp022087b.

Rate constants for the reactions of OH radicals with fluoroethane (CH3CH2F), 1,2-difluoroethane (CH2FCH2F), and 1,1-difluoroethane (CH3CHF2) were measured using the flash photolysis resonance-fluorescence technique over the temperature range of T = 210-480 K. Arrhenius plots for all three reactions exhibit noticeable curvature, and the rate constants are well represented by three-parameter modified Arrhenius expressions over the full experimental temperature range, with better than 3% precision: kCH3CH2F(T)  = 3.14×10-13×(T/ 298)2.45×exp{-103/T} cm3molecule-1s-1, kCH2FCH2F(T) = 4.33×10-14×(T/298)3.85×exp{+247/T} cm3molecule-1s-1, and kCH3CHF2(T) = 7.72×10-14×(T/298)3.02×exp{-247/T} cm3 molecule-1s-1. For the temperature range of atmospheric interest (T < 300 K), the rate constants can be well represented by standard (two-parameter) Arrhenius expressions. On the basis of all the available low-temperature data, the following rate constants are recommended for atmospheric modeling: kCH3CH2F(T < 300 K) = 2.55×10-12×exp{-730/T} cm3molecule-1s-1, kCH2FCH2F(T < 300 K) = 1.12×10-12×exp{-730/T} cm3 molecule-1s-1, and kCH3CHF2(T < 300 K) = 0.94×10-12×exp{-990/T} cm3molecule-1s-1. Using these recommendations, atmospheric lifetimes were estimated to be ca. 2.4 months, 5.5 months, and 1.4 years for CH3CH2F, CH2FCH2F, and CH3CHF2, respectively.

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Upper Atmosphere Research Program (UARP)