Abstract
The rate coefficient for the gasโphase reaction of chlorine atoms with acetone was determined as a function of temperature (273โ363 K) and pressure (0.002โ700 Torr) using complementary absolute and relative rate methods. Absolute rate measurements were performed at the lowโpressure regime (โผ2 mTorr), employing the very low pressure reactor coupled with quadrupole mass spectrometry (VLPR/QMS) technique. The absolute rate coefficient was given by the Arrhenius expression k(T) = (1.68 ยฑ 0.27) ร 10^โ11^ exp[โ(608 ยฑ 16)/T] cm^3^ molecule^โ1^ s^โ1^ and k(298 K) = (2.17 ยฑ 0.19) ร 10^โ12^ cm^3^ molecule^โ1^ s^โ1^. The quoted uncertainties are the 2ฯ (95% level of confidence), including estimated systematic uncertainties. The hydrogen abstraction pathway leading to HCl was the predominant pathway, whereas the reaction channel of acetyl chloride formation (CH~3~C(O)Cl) was determined to be less than 0.1%. In addition, relative rate measurements were performed by employing a static thermostated photochemical reactor coupled with FTIR spectroscopy (TPCR/FTIR) technique. The reactions of Cl atoms with CHF~2~CH~2~OH (3) and ClCH~2~CH~2~Cl (4) were used as reference reactions with k~3~(T) = (2.61 ยฑ 0.49) ร 10^โ11^ exp[โ(662 ยฑ 60)/T] and k~4~(T) = (4.93 ยฑ 0.96) ร 10^โ11^ exp[โ(1087 ยฑ 68)/T] cm^3^ molecule^โ1^ s^โ1^, respectively. The relative rate coefficients were independent of pressure over the range 30โ700 Torr, and the temperature dependence was given by the expression k(T) = (3.43 ยฑ 0.75) ร 10^โ11^ exp[โ(830 ยฑ 68)/T] cm^3^ molecule^โ1^ s^โ1^ and k(298 K) = (2.18 ยฑ 0.03) ร 10^โ12^ cm^3^ molecule^โ1^ s^โ1^. The quoted errors limits (2ฯ) are at the 95% level of confidence and do not include systematic uncertainties. ยฉ 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 724โ734, 2010