Rate Constants for the Reactions between OH and Perfluorinated Alkenesстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 27 марта 2017 г.
Аннотация:The rate constants for the reactions of OH radicals with fully fluorinated alkenes containing different numbers of -CF3 groups next to olefinic carbon, CF2=CF2, CF2=CFCF3, CF 3CF=CFCF3, and (CF3)2C=CFC 2F5, were measured between 230 and 480 K using the flash photolysis resonance fluorescence technique to give the following expressions: kC2F4(250-480 K) = 1.32 × 10-12 × (T/298 K)0.9 × exp(+600 K/T) cm3 molecule -1 s-1, kC3F6(230-480 K) = 9.75 ×10-14 × (T/298 K)1.94 × exp(+922 K/T) cm3 molecule-1 s-1, ktrans-C4F 8(230-370 K) = 7.50 × 10-14 × (T/298 K) 1.68 × exp(+612 K/T) cm3 molecule-1 s-1, kcis-C4F8(230-370 K) = 2.99 × 10-14 × (T/298 K)2.61 × exp(+760 K/T) cm 3 molecule-1 s-1, and kC6F 12 (250-480 K) = 2.17 × 10-15 × (T/298 K) 3.90 × exp(+1044 K/T) cm3 molecule-1 s-1. The kinetics of the OH reaction in an industrial sample of octofluoro-2-propene (a mixture of the cis- and trans-isomers of CF 3CF=CFCF3) was studied to determine the "effective" reaction rate constant for the typically industrial mixture: k [C4F8](230-480 K) = 7.89 × 10 -14 × (T/298 K)1.71 × exp(+557 K/T) cm 3 molecule-1 s-1. On the basis of these results, the atmospheric lifetimes were estimated to be 1.2, 5.3, 21, 34, and 182 days for CF2=CF2, CF3CF=CF2, trans-CF3CF=CFCF3, cis-CF3CF=CFCF3, and (CF3)2C=CFC2F5, respectively. The general pattern of halolalkene reactivity toward OH is discussed.