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. 2020 Jul 6;10(1):11078.
doi: 10.1038/s41598-020-68049-4.

Theoretical investigations on mechanisms and kinetics of the CH3CFClO2· with ClO· reaction in the atmosphere

Yunju Zhang  1 , Bing He  2 , Yuxi Sun  3
Affiliations

Theoretical investigations on mechanisms and kinetics of the CH3CFClO2· with ClO· reaction in the atmosphere

Yunju Zhang et al. Sci Rep. .

Abstract

The singlet and triplet potential energy surfaces of the ClO• radical reaction with the CH3CFClO2• radical have been investigated at the CCSD(T)/cc-pVTZ level based on the optimized geometries at the B3LYP/6-311++G(d,p) level. On the singlet potential energy surfaces (PES), the possible reaction involves association-dissociation, direct H-abstraction and Nucleophilic Substitution 2 (SN2) mechanisms. On the triplet PES, SN2 displacement and direct H-abstraction reaction pathways have been investigated, which are less competitive compared with the reaction pathways on the singlet PES. The rate constants have been calculated at 10-10 to 1010 atm and 200-3,000 K by Rice-Ramsperger-Kassel-Marcus (RRKM) theory for the important product pathways. At 200-800 K, IM1 produced (CH3CFClOOOCl) by collisonal deactivation is dominant; at high temperatures, the production P1 (CH3CFO + ClOOCl) becomes dominate. The calculated rate constants for CH3CFClO2• + ClO• are good agreement with the available experimental value. The atmospheric lifetime of CH3CFClO2• in ClO• is around 3.27 h. TD-DFT computations imply that IM1 (CH3CFClOOOCl), IM2 (CH3CFClOOClO) and IM3 (CH3CFClOClO2) will photolyze under the sunlight.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
CH3CFClO2• with ClO• reaction: optimized B3LYP geometries of the intermediates and transition stats at B3LYP/6–311 +  + G(d,p) level. The values in bold are obtained at M06-2X/6–311 +  + G(d,p) level. Bond distances are given in Å.
Figure 2
Figure 2
CH3CFClO2• with ClO• reaction: optimized B3LYP geometries of the reactants and products. Angles are given in º, and bond distances are given in Å. The values in italics are experimental data from ref 21.
Figure 3
Figure 3
Potential energy surface obtained at CCSD(T)//B3LYP level for the CH3CFClO2• + ClO• reaction.
Scheme 1
Scheme 1
The primary reaction pathways for the CH3CFClO2• with ClO• reaction.
Figure 4
Figure 4
Temperature dependence of the total and individual rate coefficients for the CH3CFClO2• + ClO• reaction at 200–3,000 K at 12 Torr of N2. The experimental data are taken from Ref 5.
Figure 5
Figure 5
Branching ratios of the primary routes for the CH3CFClO2• + ClO• reaction at 12 Torr of N2.
Figure 6
Figure 6
Forecasted rate coefficients for the total reaction and each individual product pathway of the CH3CFClO2• + ClO• reaction at 200–3,000 K and 10–10-1010 atm.
Figure 7
Figure 7
Forecasted branching ratios for the CH3CFClO2• with ClO• reaction at low-pressure limit pressure, atmospheric pressure and high-pressure limit pressure.
See this image and copyright information in PMC

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