NASA - National Aeronautics and Space Administration

Rate constants for the gas phase reactions of OH radicals with three partially fluorinated ethers, CH₃OCF₃ (k_HFE‑143a), CH₃OCHF₂ (k_HFE‑152a), and CHF₂OCH₂CF₃ (k_HFE‑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: k_HFE‑143a(T) = (1.10 ± 0.20)×10⁻¹²×exp{−(1324 ± 61)/T} cm³molecule⁻¹s⁻¹; k_HFE‑152a(T) = (11.6 ± 4.2)×10⁻¹²×exp{−(1728 ± 133)/T} cm³molecule⁻¹s⁻¹; and k_HFE‑245fa2(T) = (3.04 ± 0.57)×10⁻¹²×exp{−(1665 ± 66)/T} cm³molecule⁻¹s⁻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.