Theoretical study of the kinetics of chlorine atom abstraction from chloromethanes by atomic chlorine

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 asThe rate constants for the reverse reactions CH3/CH2Cl/CHCl2/CCl3 + Cl2 were calculated via the equilibrium constants derived theoretically. The kinetic equationsallow 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.

One‐Pot Intermolecular C–S Self‐Coupling of Dimethyl Sulfoxide Promoted by Molybdenum Pentachloride

“…Interestingly, evolution of HCl from the reaction mixtures (Scheme ) was detected in every case (see the Experimental Section for details). In the absence of C–H activation processes (see above), this may constitute indirect confirmation of the formation of elemental chlorine , …”

Cl Atom-Initiated Photo-Oxidation Reactions of Vinyl Trifluoroacetate and Allyl Trifluoroacetate in Tropospheric Conditions

“…28−30 Cartesian coordinates and vibrational frequencies of all of the stationary points are tabulated in Tables S1−S4 of the Supporting Information (SI). The <S 2 > values 31,32 of all open-shell TSs and Ps were analyzed before and after annihilation and are listed in Tables S5 and S6 of the SI. The analysis implied that there was a significant amount of spin contamination.…”

“…This theory is a post-Hartree–Fock method, which is widely used for the accurate determination of the correlation energy. , It is also well known for predicting precise results for thermochemical and kinetic parameters. − Cartesian coordinates and vibrational frequencies of all of the stationary points are tabulated in Tables S1–S4 of the Supporting Information (SI). The < S 2 > values , of all open-shell TSs and Ps were analyzed before and after annihilation and are listed in Tables S5 and S6 of the SI. The analysis implied that there was a significant amount of spin contamination.…”

Combustion and Pyrolysis Kinetics of Chloropicrin

“…32 (3 The chlorine atom abstraction reaction was also considered (reactions 8). The kinetic parameters were estimated by analogy with the Cl-atom abstraction from CCl4 calculated theoretically by Brudnik et al 37 . The values were recalculated from the high-pressure limit rate constant given in the paper.…”