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

Abstract

Relative rate techniques were used to estimate k(OH+HFE-7100) ≈ 1.2 × 10 -14 cm 3 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 C 4 F 9 OCH 2 and C 4 F 9 OCH 2 O 2 radicals at 296 K. At 300 nm σ(C 4 F 9 OCH 2 ) ) (5.80 ( 0.76) × 10 -19 and at 250 nm σ(C 4 F 9 OCH 2 O 2 ) ) (2.24 ( 0.24) × 10 -18 cm 2 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 C 4 F 9 OCH 2 and C 4 F 9 OCH 2 O 2 radicals, the reaction of C 4 F 9 OCH 2 radicals with O 2 , and the reactions of C 4 F 9 -OCH 2 O 2 radicals with NO and NO 2 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 cm 3 molecule -1 s -1 , respectively. Using a pulse radiolysis method we measured k(F+HFE-7100) ) (1.6 ( 0.6) × 10 -11 cm 3 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 C 4 F 9 OC(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 cm 3 molecule -1 s -1 , respectively. Finally, it was determined that the sole atmospheric fate of C 4 F 9 OCH 2 O‚ radicals is reaction with O 2 to give C 4 F 9 OC(O)H (perfluorobutyl formate). The results are discussed with respect to the atmospheric chemistry of HFE-7100.

Contribution of the Atmospheric Chlorine Reactions to the Degradation of Greenhouse Gases: CFCs Substitutes

“…Taking into account error limits, the results obtained under low-pressure conditions in this work are in good agreement with those obtained in relative experiments at atmospheric pressure (700 Torr) and room temperature for all the studied HFEs. Our samples of both HFE-7200 and HFE-7100 were a mixture of two isomers, however in the studies of Christensen et al (1998) and Wallington et al (1997), the authors had access to pure samples of n-HFE-7200, n-HFE-7100, i-HFE-7200, and i-HFE-7100 and could study their reactions with chlorine atoms separately. They found no discernible difference in reactivity showing that kinetic rate constant for these isomer mixtures are expected to be independent of composition.…”

An Environmentally Friendly Class of Fluoropolyether: α,ω-Dialkoxyfluoropolyethers

“…The incorporation of two alkoxy-groups provides reactive sites, which limit their atmospheric lifetime [1][2][3]; therefore, when compared with perfluoropolyethers (PFPEs), they have a lower environmental impact in terms of global warming potential (GWP) [1]. Furthermore, perfluorinated ether units from polymeric backbones also makes them well characterized by typical properties of PFPEs, like high thermal and chemical stability, no acute toxicity and excellent heat exchange properties [4].…”

Hydrogen-Atom Abstraction Reaction of CF3CH2OCF3by Hydroxyl Radical

“…12 Therefore, considerable attention has been paid in recent years to perform experimental and theoretical studies on the decomposition kinetics of HFEs. [13][14][15][16] Tropospheric degradation is expected to be initiated mainly by the attack of OH radicals in the gas phase 17 and CF 3 CH 2 OCF 3 (HFE-246cb2) may undergo H atom abstraction as follows.…”