Kinetics and mechanisms of CF3CHFOCH3, CF3CHFOC(O)H, and FC(O)OCH3 reactions with OH radicals

The kinetics and mechanism of oxidation of CF3CHFOCH3 was studied using an 11.5-dm(3) environmental reaction chamber. OH radicals were produced by UV photolysis of an O-3-H2O-He mixture at an initial pressure of 200 Torr in the chamber. The rate constant of the reaction of CF3CHFOCH3 with OH radicals (k(1)) was determined to be (1.77 +/- 0.69) x 10(-12) exp[(-720 +/- 110)/T] cm(3) molecule(-1) s(-1) by means of a relative rate method at 253-328 K. The mechanism of the reaction was investigated by FT-IR spectroscopy at 298 K. CF3CHFOC(O)H, FC(O)OCH3, and COF2 were determined to be the major products. The branching ratio (k(1a)/k(1b)) for the reactions CF3CHFOCH3 + OH -> CF3CHFOCH2 center dot + H2O (k(1a)) and CF3CHFOCH3 + OH -> (CF3CFOCH3)-O-center dot + H2O (k(1b)) was estimated to be 4.2:1 at 298 K from the yields of CF3CHFOC(O)H, FC(O)OCH3, and COF2. The rate constants of the reactions of CF3CHFOC(O)H (k(2)) and FC(O)OCH3 (k(3)) with OH radicals were determined to be (9.14 +/- 2.78) x 10(-13) exp[(-1190 +/- 90)/T] and (2.10 +/- 0.65) x 10(-13) exp[(-630 +/- 90)/T] cm(3) molecule(-1) s(-1), respectively, by means of a relative rate method at 253-328 K. The rate constants at 298 K were as follows: k(1) = (1.56 +/- 0.06) x 10-(13), k(2) = (1.67 +/- 0.05) x 10(-14), and k(3)) (2.53 +/- 0.07) x 10(-14) cm(3) molecule(-1) s(-1). The tropospheric lifetimes of CF3CHFOCH3, CF3CHFOC(O) H, and FC(O)OCH3 with respect to reaction with OH radicals were estimated to be 0.29, 3.2, and 1.8 years, respectively.