Atmospheric Chemistry of (E)- and (Z)-CF3CF2CH═CHCF2CF3 (HFO-153-10mczz): Kinetics and Mechanisms of the Reactions with Cl Atoms, OH Radicals, and O3.

Abstract

Smog chamber experiments were conducted to establish the atmospheric chemistry of (E)- and (Z)-CF₃CF₂CH═CHCF₂CF₃. Kinetics of the reactions of the two compounds with Cl atoms and OH radicals were measured using relative rate techniques, giving k(Cl + (E)-CF₃CF₂CH═CHCF₂CF₃) = (5.63 ± 0.84) × 10^-12, k(Cl + (Z)-CF₃CF₂CH═CHCF₂CF₃) = (1.17 ± 0.20) × 10^-11, k(OH + (E)-CF₃CF₂CH═CHCF₂CF₃) = (1.64 ± 0.21) × 10^-13, and k(OH + (Z)-CF₃CF₂CH═CHCF₂CF₃) = (3.13 ± 0.38) × 10^-13 cm³ molecule^-1 s^-1 in 680 Torr air/N₂/O₂ diluents at 296 ± 2 K. Rate coefficients for the reactions with O₃, k(O₃ + (E)-CF₃CF₂CH═CHCF₂CF₃) ∼ 1 × 10^-22 and k(O₃ + (Z)-CF₃CF₂CH═CHCF₂CF₃) ≤ 5× 10^-24 cm³ molecule^-1 s^-1, were established using absolute techniques in a 680 Torr air diluent and 296 ± 2 K. The Cl reaction with (E)-CF₃CF₂CH═CHCF₂CF₃ gives CF₃CF₂CHClC(O)CF₂CF₃ as the sole oxidation product, whereas the reaction with (Z)-CF₃CF₂CH═CHCF₂CF₃ also gives rise to the formation of the (E)-isomer in minor yields. The reaction of OH radicals with CF₃CF₂CH═CHCF₂CF₃ gives CF₃CF₂CHO in a yield of 177 ± 17%. The main atmospheric fate of (E)- and (Z)-CF₃CF₂CH═CHCF₂CF₃ is the reaction with OH radicals, resulting in overall atmospheric lifetime estimates of 71 and 37 days, for (E)- and (Z)-CF₃CF₂CH═CHCF₂CF₃, respectively. The IR absorption cross sections are reported, and the global warming potentials of (E)- and (Z)-CF₃CF₂CH═CHCF₂CF₃ for the 20-, 100-, and 500-year time horizons are calculated to be 36, 10, and 3 for the (E)-isomer and 11, 3, and 1 for the (Z)-isomer, respectively. Atmospheric processing of (E)- and (Z)-CF₃CF₂CH═CHCF₂CF₃ is expected to yield CF₃CF₂COOH and CF₃COOH in yields of <10%. This study provides a comprehensive description of the atmospheric chemistry and fate of (E)- and (Z)-CF₃CF₂CH═CHCF₂CF₃.