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Kinetics and mechanism of the gas phase reaction of atomic chlorine with CH 2ICl at 206-432 K

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  • M. Bilde
  • J. Sehested
  • Nielsen, Ole John
  • T. J. Wallington
  • R. J. Meagher
  • M. E. McIntosh
  • C. A. Piety
  • J. M. Nicovich
  • P. H. Wine

The title reaction was studied using two different experimental techniques: laser flash photolysis with resonance fluorescence detection of Cl atoms and continuous photolysis with FTIR detection of end products. Over the temperature range 206-432 K the rate constant for reaction of Cl atoms with CH 2ICl is given (to within ±15%) by the Arrhenius expression k 1 = 4.4 × 10 -11 exp(195/T) cm 3 molecule -1 s -1, which gives k 1 = 8.5 × 10 -11 cm 3 molecule -1 s -1 at 298 K. Variation of the total pressure of N 2 diluent over the range 5-700 Torr at 295 K had no discernible (<10%) effect on the rate of reaction. At 295 K in 100-700 Torr of N 2 the reaction proceeds via iodine transfer to give CH 2Cl radicals. As part of this work the rate constant k(CH 2Cl+O 2+M) was measured at 295 K in the presence of 1-800 Torr of N 2 diluent. The results were well described by the Troe expression with a broadening factor F c of 0.6 and limiting low- and high-pressure rate constants of k 0 = (1.8 ± 0.1) × 10 -30 cm 6 molecule -2 s -1 and k = (3.3 ± 0.3) × 10 -12 cm 3 molecule -1 s -1. The results are discussed with respect to the available literature for reactions of Cl atoms with halogenated organic compounds and the potential role of the title reaction in atmospheric chemistry.

OriginalsprogEngelsk
TidsskriftJournal of Physical Chemistry A
Vol/bind101
Udgave nummer43
Sider (fra-til)8035-8041
Antal sider7
ISSN1089-5639
StatusUdgivet - 23 okt. 1997

ID: 227486656