Atmospheric chemistry of Z- and E-CF3CH
CHCF3†
Abstract
The atmospheric fates of Z- and E-CF3CHCHCF3 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
CHCF3) = (2.59 ± 0.47) × 10−11, k(Cl + E-CF3CH
CHCF3) = (1.36 ± 0.27) × 10−11, k(OH + Z-CF3CH
CHCF3) = (4.21 ± 0.62) × 10−13, k(OH + E-CF3CH
CHCF3) = (1.72 ± 0.42) × 10−13, k(OD + Z-CF3CH
CHCF3) = (6.94 ± 1.25) × 10−13, k(OD + E-CF3CH
CHCF3) = (5.61 ± 0.98) × 10−13, k(O3 + Z-CF3CH
CHCF3) = (6.25 ± 0.70) × 10−22, and k(O3 + E-CF3CH
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
CHCF3 reacts with Cl atoms to give CF3CHClC(O)CF3 in a yield indistinguishable from 100%. Z-CF3CH
CHCF3 reacts with Cl atoms to give (95 ± 10)% CF3CHClC(O)CF3 and (7 ± 1)% E-CF3CH
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
CHCF3 is reaction with OH radicals. The atmospheric lifetimes of Z- and E-CF3CH
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
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
CHCF3.