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Atmospheric chemistry of HFE-7100 (C4F9OCH3): Reaction with OH radicals, UV spectra and kinetic data for C4F9OCH2• and C4F9OCH2O2• radicals, and the atmospheric fate of C4F9OCH2O• radicals

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  • T. J. Wallington
  • W. F. Schneider
  • J. Sehested
  • M. Bilde
  • J. Platz
  • Nielsen, Ole John
  • L. K. Christensen
  • M. J. Molina
  • L. T. Molina
  • P. W. Wooldridge

Relative rate techniques were used to estimate k(OH+HFE-7100) ≈ 1.2 × 10-14 cm3 molecule-1 s-1 at 295 K leading to an estimate of ≈5 years for the atmospheric lifetime of HFE-7100 (HFE = hydrofluoroether). Pulse radiolysis transient UV absorption spectroscopy was used to study the ultraviolet absorption spectra and kinetics of C4F9OCH2 and C4F9OCH2O2 radicals at 296 K. At 300 nm σ(C4F9OCH2) = (5.80 ± 0.76) × 10-19 and at 250 nm σ(C4F9OCH2O2) = (2.24 ± 0.24) × 10-18 cm2 molecule-1. Both UV spectra showed two absorption maxima, one below 230 nm and one at 290 nm. Rate constants for the self-reactions of C4F9OCH2 and C4F9OCH2O2 radicals, the reaction of C4F9OCH2 radicals with O2, and the reactions of C4F9OCH2O2 radicals with NO and NO2 were (3.5 ± 0.8) × 10-11, (1.35 ± 0.17) × 10-11 (uncorrected for possible secondary chemistry), (2.5 ± 0.5) × 10-12, (8.5 ± 2.5) × 10-12, and (8.8 ± 1.8) × 10-12 cm3 molecule-1 s-1, respectively. Using a pulse radiolysis method we measured k(F+HFE-7100) = (1.6 ± 0.6) × 10-11 cm3 molecule-1 s-1. Using a Fourier transform infrared spectroscopic technique rate, constants for the reaction of F and Cl atoms with HFE-7100 and Cl atoms with C4F9OC(O)H were determined to be (1.3 ± 0.3) × 10-11, (9.7 ± 1.4) × 10-14, and (1.6 ± 0.7) × 10-14 cm3 molecule-1 s-1, respectively. Finally, it was determined that the sole atmospheric fate of C4F9OCH2O• radicals is reaction with O2 to give C4F9OC(O)H (perfluorobutyl formate). The results are discussed with respect to the atmospheric chemistry of HFE-7100.

OriginalsprogEngelsk
TidsskriftJournal of Physical Chemistry A
Vol/bind101
Udgave nummer44
Sider (fra-til)8264-8274
Antal sider11
ISSN1089-5639
StatusUdgivet - 30 okt. 1997

ID: 227486483