Kinetic, mechanistic and temperature dependence study of Cl reactions with CH3OC(O)H and CH3CH2OC(O)H. Atmospheric implications

' Reactions of Cl atoms with CH3OC(O) H (1) and CH3CH2OC(O)H (2) have been studied using the Discharge Flow-Mass Spectrometric (DF-MS) method. The study has been carried out at 1 Torr total pressure under pseudo-first-order conditions in the temperature range 253 K to 333 K to approach the tropospheric temperature pro. le. The measured room temperature rate coefficients are k(1) = (1.01 +/- 0.15) x 10(-12) cm(3) molecule(-1) s(-1) and k(2) = (8.78 +/- 1.22) x 10(-12) cm(3) molecule(-1) s(-1) (errors are 2 sigma) and the. tted Arrhenius expressions, k(1) = (1.7 +/- 1.4) x 10(-11) exp-(810 +/- 250)/T cm(3) molecule(-1) s(-1) and k(2) = (5.5 +/- 4.8) x 10(-11) exp-(556 +/- 268)/T cm(3) molecule(-1) s(-1) (errors are 2 sigma). The reactions proceed through the abstraction of an H atom to form HCl and the corresponding radical. At 298 K and 1 Torr, yields on HCl of 0.95 +/- 0.09 (error is 2 sigma) for reaction (1) and 0.96 +/- 0.11 (error is 2s) for reaction (2) have been measured. The tropospheric lifetimes are calculated and discussed.