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Photochemical Properties of Hydrofluoroethers CH3OCHF2, CH3OCF3, and CHF2OCH2CF3: Reactivity toward OH, IR Absorption Cross Sections, Atmospheric Lifetimes, and Global Warming Potentials

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posted on 13.11.2014, 00:00 by Vladimir L. Orkin, Victor G. Khamaganov, Andrey G. Guschin
Rate constants for the gas phase reactions of OH radicals with three partially fluorinated ethers, CH3OCF3 (kHFE‑143a), CH3OCHF2 (kHFE‑152a), and CHF2OCH2CF3 (kHFE‑245fa2), were measured using a discharge flow–electron paramagnetic resonance technique over the temperature range 298–460 K. The temperature dependences of the rate constants can be represented by the following expressions: kHFE‑143a(T) = (1.10 ± 0.20) × 10–12 × exp{−(1324 ± 61)/T} cm3 molecule–1 s–1; kHFE‑152a(T) = (11.6 ± 4.2) × 10–12 × exp{−(1728 ± 133)/T} cm3 molecule–1 s–1; and kHFE‑245fa2(T) = (3.04 ± 0.57) × 10–12 × exp{−(1665 ± 66)/T} cm3 molecule–1 s–1. The atmospheric lifetimes due to reactions with tropospheric OH were estimated to be 5.2, 1.9, and 5.6 years, respectively. The IR absorption cross sections of these fluorinated ethers were measured between 400 and 2000 cm–1, and their global warming potentials were estimated.