Rate coefficients for the reaction of the acetyl radical, CH3CO, with Cl2 between 253 and 384 K

✍ Scribed by T. Gierczak; B. Rajakumar; Jonathan E. Flad; James B. Burkholder

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 295 KB
• Volume: 41
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20430

✦ Synopsis

Abstract

Rate coefficients, k, for the gas‐phase reaction CH~3~CO + Cl~2~ → products (2) were measured between 253 and 384 K at 55–200 Torr (He). Rate coefficients were measured under pseudo‐first‐order conditions in CH~3~CO with CH~3~CO produced by the 248‐nm pulsed‐laser photolysis of acetone, CH~3~C(O)CH~3~, or 2,3‐butadione, CH~3~C(O)C(O)CH~3~. The loss of CH~3~CO was monitored by cavity ring‐down spectroscopy (CRDS) at 532 nm. Rate coefficients were determined by first‐order kinetic analysis of the CH~3~CO temporal profiles for [Cl~2~] < 1 × 10^14^ molecule cm^−3^ and the analysis of the CRDS profiles by the simultaneous kinetics and ring‐down method for experiments performed with [Cl~2~] > 1 × 10^14^ molecule cm^−3^. k~2~(T) was found to be independent of pressure, with k~2~(296 K) = (3.0 ± 0.5) × 10^−11^ cm^3^ molecule^−1^ s^−1^. k~2~(T) showed a weak negative temperature dependence that is well reproduced by the Arrhenius expression k~2~(T) = (2.2 ± 0.8) × 10^−11^ exp[(85 ± 120)/T] cm^3^ molecule^−1^ s^−1^. The quoted uncertainties in k~2~(T) are at the 2σ level (95% confidence interval) and include estimated systematic errors. A comparison of the present work with previously reported rate coefficients for the CH~3~CO + Cl~2~ reaction is presented. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 543–553, 2009