Article

Atmospheric Chemistry Of Z- And E-Cf3Chchcf3

The atmospheric fates of Z- and E-CF3CH[double bond, length as m-dash]CHCF3 have been studied, investigating the kinetics and the products of the reactions of the two compounds with Cl atoms, OH radicals, OD radicals, and O3. FTIR smog chamber experiments measured: k(Cl + Z-CF3CH[double bond, length as m-dash]CHCF3) = (2.59 ± 0.47) × 10−11, k(Cl + E-CF3CH[double bond, length as m-dash]CHCF3) = (1.36 ± 0.27) × 10−11, k(OH + Z-CF3CH[double bond, length as m-dash]CHCF3) = (4.21 ± 0.62) × 10−13, k(OH + E-CF3CH[double bond, length as m-dash]CHCF3) = (1.72 ± 0.42) × 10−13, k(OD + Z-CF3CH[double bond, length as m-dash]CHCF3) = (6.94 ± 1.25) × 10−13, k(OD + E-CF3CH[double bond, length as m-dash]CHCF3) = (5.61 ± 0.98) × 10−13, k(O3 + Z-CF3CH[double bond, length as m-dash]CHCF3) = (6.25 ± 0.70) × 10−22, and k(O3 + E-CF3CH[double bond, length as m-dash]CHCF3) = (4.14 ± 0.42) × 10−22 cm3 molecule−1 s−1 in 700 Torr of air/N2/O2 diluents at 296 ± 2 K. E-CF3CH[double bond, length as m-dash]CHCF3 reacts with Cl atoms to give CF3CHClC(O)CF3 in a yield indistinguishable from 100%. Z-CF3CH[double bond, length as m-dash]CHCF3 reacts with Cl atoms to give (95 ± 10)% CF3CHClC(O)CF3 and (7 ± 1)% E-CF3CH[double bond, length as m-dash]CHCF3. CF3CHClC(O)CF3 reacts with Cl atoms to give the secondary product CF3C(O)Cl in a yield indistinguishable from 100%, with the observed co-products C(O)F2 and CF3O3CF3. The main atmospheric fate for Z- and E-CF3CH[double bond, length as m-dash]CHCF3 is reaction with OH radicals. The atmospheric lifetimes of Z- and E-CF3CH[double bond, length as m-dash]CHCF3 are estimated as 27 and 67 days, respectively. IR absorption cross sections are reported and the global warming potentials (GWPs) of Z- and E-CF3CH[double bond, length as m-dash]CHCF3 for the 100 year time horizon are calculated to be GWP100 = 2 and 7, respectively. This study provides a comprehensive description of the atmospheric fate and impact of Z- and E-CF3CH[double bond, length as m-dash]CHCF3.

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