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Atmospheric chemistry of CH2BrCl: Kinetics and mechanism of the reaction of F atoms with CH2BrCl and fate of the CHBrClO. radical

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The reaction of F atoms with CH2BrCl was studied using a pulsed radiolysis technique and found to proceed via two channels: direct hydrogen abstraction and adduct formation. The adduct exists in equilibrium with F atoms and CH2BrCl. The equilibrium constant K4 = [Adduct]/([CH2BrCl][F]) = (4.2 ± 1.0) × 10-16 cm3molecule-1. In 1000 mbar total pressure of SF6 at 294 ± 2 K, the yield of the adduct is 68 ± 11% and the overall rate constant for reaction of F atoms with CH2BrCl is k4 (1000 mbar) = (3.6 ± 0.9) × 10-11 cm3 molecule-1 s-1. The adduct reacts with NO with a rate constant of (2.09 ± 0.41) × 10-11 cm3 molecule-1 s-1. The atmospheric fate of the alkoxy radical CHBrClO is Br atom elimination, which occurs at a rate estimated to be >2 × 106 s-1 in 700 Torr of air at 295 K. Relative rate techniques were used to measure k(Cl + CH2BrCl) = (4.2 ± 0.5) × 10-13 and k(F + CH2BrCl → CHBrCl + HF) = (1.2 ± 0.4) × 10-11 cm3 molecule-1 s-1. These results are compared to the available literature data.

OriginalsprogEngelsk
TidsskriftJournal of Physical Chemistry A
Vol/bind101
Udgave nummer30
Sider (fra-til)5477-5488
Antal sider12
ISSN1089-5639
StatusUdgivet - 24 jul. 1997

ID: 227486919