Atmospheric Oxidation Mechanism and Kinetics of Hydrofluoroethers, CH3OCF3, CH3OCHF2, and CHF2OCH2CF3, by OH Radical: A Theoretical Study

In the present work, the reaction mechanism of two segregated hydrofluoroethers (HFEs), CH3OCF3 (HFE-143a) and CH3OCHF2 (HFE-152a), and a nonsegregated HFE, CHF2OCH2CF3 (HFE-245fa2), with OH radical is studied using electronic structure calculations. The initial reaction between HFE and OH radical is studied by considering two (three for CHF2OCH2CF3) pathways, H-atom abstraction and C–O bond breaking, OH addition reaction and C–C bond breaking, and OH addition reaction, which leads to the formation of alkyl radical intermediate. The dominant atmospheric fate of initially formed alkyl radical intermediate is its reaction with O2. The peroxy radicals thus formed exit through the reaction with HO2 radical and NO radical resulting in the formation of products, carbonyl fluoride (COF2), trifluoromethylformate, trifluoro(hydroperoxymethoxy)methane, difluoro(hydroperoxy methoxy)methane, difluoromethylformate, 2-(difluoromethoxy)-1,1,1-trifluoro-2-hydroperoxyethane, and difluoromethyl ester. The rate constant is ...