Kinetic study of the reaction CCl sub 3 + O sub 2 + M yields CCl sub 3 O sub 2 + M from 1 to 760 Torr and from 233 to 333 K

Journal Article · Thu Sep 19 04:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100172a037· OSTI ID:5184728

Danis, F; Caralp, F; Rayez, M T; Lesclaux, R ^[1]

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1. Univ. de Bordeaux (France)

The kinetics of reaction 1, Cl{sub 3} + O{sub 2} + M {yields} CCl{sub 3}O{sub 2} + M, has been investigated in detail as a function of temperature and over a large pressure range. At low pressure, 0.8-12 Torr, the reaction was investigated by laser photolysis and time-resolved mass spectrometry, while at high pressure (760 Torr), flash photolysis with UV absorption spectrometry was employed. At the low-pressure limit, the rate expression, k{sub 1}(0) = (1.6 {+-} 0.3) {times} 10{sup {minus}30}(T/298){sup {minus}(6.3 {+-} 0.5)} cm{sup 6}/molecule{sup 2} sec (M = N{sub 2}), exhibits a quite strong negative temperature coefficient. The obtained strong collision rate expression, 7.0 {times} 10{sup {minus}30}(t/298){sup {minus}4.3} cm{sup 6}/molecule{sup 2} sec, using either RRKM calculations of Troe's factorized expression, is unable to reproduce the experimental temperature dependence, unless an unreasonably strong temperature dependence is assigned to the collisional efficiency factor: {beta}{sub c} = 0.23(t/298){sup {minus}2.0} (M = N{sub 2}). Similar results are obtained for other chlorofluoromethyl radicals. The falloff curves were constructed by using RRKM calculations obtained by adjusting {beta}{sub c} and the transition-state model, in order to reproduce the experimental data. The rate expression at the high-pressure limit was derived from these calculations k{sub 1}({infinity}) = (3.2 {+-} 0.7) {times} 10{sup {minus}12}(T/298){sup {minus}(1.2 {+-} 0.4)} cm{sup 3}/molecule sec. All the parameters to be used in Troe's analytical expression for calculating the biomolecular rate constant at any pressure and temperature are given. The rate constant at the low-pressure limit k{sub 1}(0) is more than an order of magnitude lower than for the CF{sub 3} radical. The RRKM calculations show that this arises from a large difference in the C-O bond dissociation energies in the corresponding peroxy radicals.

• OSTI ID: 5184728
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:19; ISSN JPCHA; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540120 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ABSORPTION SPECTROSCOPY
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELECTRONIC STRUCTURE
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
KINETICS
LASER RADIATION
LOW PRESSURE
MASS SPECTROSCOPY
MATHEMATICAL MODELS
NONMETALS
NUMERICAL DATA
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDATION
OXYGEN
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PRESSURE DEPENDENCE
RADIATIONS
RADICALS
REACTION KINETICS
RESOLUTION
SPECTROSCOPY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
THEORETICAL DATA
TIME RESOLUTION
TIMING PROPERTIES