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Atmospheric Chemistry of (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C(O)OCH3

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journal contribution
posted on 22.10.2015, 00:00 by Freja From Østerstrøm, Timothy J. Wallington, Mads P. Sulbaek Andersen, Ole John Nielsen
Smog chambers with in situ FTIR detection were used to measure rate coefficients in 700 Torr of air and 296 ± 2 K of: k(Cl+(CF3)2CHOCH3) = (5.41 ± 1.63) × 10–12, k(Cl+(CF3)2CHOCHO) = (9.44 ± 1.81) × 10–15, k(Cl+CF3C­(O)­OCH3) = (6.28 ± 0.98) × 10–14, k(OH+(CF3)2CHOCH3) = (1.86 ± 0.41) × 10–13, and k(OH+(CF3)2CHOCHO) = (2.08 ± 0.63) × 10–14 cm3 molecule–1 s–1. The Cl atom initiated oxidation of (CF3)2CHOCH3 gives (CF3)2CHOCHO in a yield indistinguishable from 100%. The OH radical initiated oxidation of (CF3)2CHOCH3 gives the following products (molar yields): (CF3)2CHOCHO (76 ± 8)%, CF3C­(O)­OCH3 (16 ± 2)%, CF3C­(O)­CF3 (4 ± 1)%, and C­(O)­F2 (45 ± 5)%. The primary oxidation product (CF3)2CHOCHO reacts with Cl atoms to give secondary products (molar yields): CF3C­(O)­CF3 (67 ± 7)%, CF3C­(O)­OCHO (28 ± 3)%, and C­(O)­F2 (118 ± 12)%. CF3C­(O)­OCH3 reacts with Cl atoms to give: CF3C­(O)­OCHO (80 ± 8)% and C­(O)­F2 (6 ± 1)%. Atmospheric lifetimes of (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C­(O)­OCH3 were estimated to be 62 days, 1.5 years, and 220 days, respectively. The 100-year global warming potentials (GWPs) for (CF3)2CHOCH3, (CF3)2CHOCHO, and CF3C­(O)­OCH3 are estimated to be 6, 121, and 46, respectively. A comprehensive description of the atmospheric fate of (CF3)2CHOCH3 is presented.

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