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Theoretical study of the kinetics of chlorine atom abstraction from chloromethanes by atomic chlorine
- Source :
- Journal of Molecular Modeling
- Publication Year :
- 2013
- Publisher :
- Springer Science and Business Media LLC, 2013.
-
Abstract
- Ab initio calculations at the G3 level were used in a theoretical description of the kinetics and mechanism of the chlorine abstraction reactions from mono-, di-, tri- and tetra-chloromethane by chlorine atoms. The calculated profiles of the potential energy surface of the reaction systems show that the mechanism of the studied reactions is complex and the Cl-abstraction proceeds via the formation of intermediate complexes. The multi-step reaction mechanism consists of two elementary steps in the case of CCl4 + Cl, and three for the other reactions. Rate constants were calculated using the theoretical method based on the RRKM theory and the simplified version of the statistical adiabatic channel model. The temperature dependencies of the calculated rate constants can be expressed, in temperature range of 200–3,000 K as\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \begin{array}{*{20}c} {k\left( {\mathrm{C}{{\mathrm{H}}_3}\mathrm{C}\mathrm{l}+\mathrm{Cl}} \right) = 2.08\times {10^{-11 }}\times {{{\left( {{{\mathrm{T}} \left/ {300 } \right.}} \right)}}^{1.63 }}\times\exp \left( {{-12780 \left/ {\mathrm{T}} \right.}} \right)\ }{\mathrm{c}{{\mathrm{m}}^3}\mathrm{molecul}{{\mathrm{e}}^{-1 }}{{\mathrm{s}}^{-1 }}} \\ {k\left( {\mathrm{C}{{\mathrm{H}}_2}\mathrm{C}{{\mathrm{l}}_2}+\mathrm{Cl}} \right) = 2.36\times {10^{-11 }}\times {{{\left( {{{\mathrm{T}} \left/ {300 } \right.}} \right)}}^{1.23 }}\times\exp \left( {{-10960 \left/ {\mathrm{T}} \right.}} \right)}{\mathrm{c}{{\mathrm{m}}^3}\mathrm{molecul}{{\mathrm{e}}^{-1 }}{{\mathrm{s}}^{-1 }}} \\ {k\left( {\mathrm{C}\mathrm{HC}{{\mathrm{l}}_3}+\mathrm{Cl}} \right) = 5.28\times {10^{-11 }}\times {{{\left( {{{\mathrm{T}} \left/ {300 } \right.}} \right)}}^{0.97 }}\times\exp \left( {{-9200 \left/ {\mathrm{T}} \right.}} \right)}{\mathrm{c}{{\mathrm{m}}^3}\mathrm{molecul}{{\mathrm{e}}^{-1 }}{{\mathrm{s}}^{-1 }}} \\ {k\left( {\mathrm{C}\mathrm{C}{{\mathrm{l}}_4}+\mathrm{Cl}} \right) = 1.51\times {10^{-10 }}\times {{{\left( {{{\mathrm{T}} \left/ {300 } \right.}} \right)}}^{0.58 }}\times \exp \left( {{-7790 \left/ {\mathrm{T}} \right.}} \right)}{\mathrm{c}{{\mathrm{m}}^3}\mathrm{molecul}{{\mathrm{e}}^{-1 }}{{\mathrm{s}}^{-1 }}} \\ \end{array} $$\end{document} The rate constants for the reverse reactions CH3/CH2Cl/CHCl2/CCl3 + Cl2 were calculated via the equilibrium constants derived theoretically. The kinetic equations\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \begin{array}{*{20}c} {k\left( {\mathrm{C}{{\mathrm{H}}_3}+\mathrm{C}{{\mathrm{l}}_2}} \right) = 6.70\times {10^{-13 }}\times {{{\left( {{{\mathrm{T}} \left/ {300 } \right.}} \right)}}^{1.51 }}\times \exp \left( {{270 \left/ {\mathrm{T}} \right.}} \right)}{\mathrm{c}{{\mathrm{m}}^3}\mathrm{molecul}{{\mathrm{e}}^{-1 }}{{\mathrm{s}}^{-1 }}} \\ {k\left( {\mathrm{C}{{\mathrm{H}}_2}\mathrm{C}\mathrm{l}+\mathrm{C}{{\mathrm{l}}_2}} \right) = 7.34\times {10^{-14 }}\times {{{\left( {{{\mathrm{T}} \left/ {300 } \right.}} \right)}}^{1.43 }}\times \exp \left( {{390 \left/ {\mathrm{T}} \right.}} \right)}{\mathrm{c}{{\mathrm{m}}^3}\mathrm{molecul}{{\mathrm{e}}^{-1 }}{{\mathrm{s}}^{-1 }}} \\ {k\left( {\mathrm{C}\mathrm{HC}{{\mathrm{l}}_2}+\mathrm{C}{{\mathrm{l}}_2}} \right) = 6.81\times {10^{-14 }}\times {{{\left( {{{\mathrm{T}} \left/ {300 } \right.}} \right)}}^{1.60 }}\times \exp \left( {{-370 \left/ {\mathrm{T}} \right.}} \right)}{\mathrm{c}{{\mathrm{m}}^3}\mathrm{molecul}{{\mathrm{e}}^{-1 }}{{\mathrm{s}}^{-1 }}} \\ {k\left( {\mathrm{C}\mathrm{C}{{\mathrm{l}}_3}+\mathrm{C}{{\mathrm{l}}_2}} \right) = 1.43\times {10^{-13 }}\times {{{\left( {{{\mathrm{T}} \left/ {300 } \right.}} \right)}}^{1.52 }}\times \exp \left( {{-550 \left/ {\mathrm{T}} \right.}} \right)}{\mathrm{c}{{\mathrm{m}}^3}\mathrm{molecul}{{\mathrm{e}}^{-1 }}{{\mathrm{s}}^{-1 }}} \\ \end{array} $$\end{document}allow a very good description of the reaction kinetics. The derived expressions are a substantial supplement to the kinetic data necessary to describe and model the complex gas-phase reactions of importance in combustion and atmospheric chemistry.
- Subjects :
- Models, Molecular
Reaction mechanism
Kinetics
chemistry.chemical_element
Chlorine abstraction
Catalysis
Inorganic Chemistry
Chemical kinetics
Nuclear physics
chemistry.chemical_compound
Reaction rate constant
Ab initio quantum chemistry methods
Gas-phase reactions
Chloromethanes
Chlorine
Computer Simulation
Physical and Theoretical Chemistry
Air Pollutants
Original Paper
Chemistry
Chloromethane
Organic Chemistry
Computer Science Applications
Models, Chemical
Computational Theory and Mathematics
Potential energy surface
Methyl Chloride
Quantum Theory
Thermodynamics
Physical chemistry
Gases
Subjects
Details
- ISSN :
- 09485023 and 16102940
- Volume :
- 19
- Database :
- OpenAIRE
- Journal :
- Journal of Molecular Modeling
- Accession number :
- edsair.doi.dedup.....4d662377d935fb9c677d9690211bc02b