Issue 4, 2024

Oxidation pathways and kinetics of the 1,1,2,3-tetrafluoropropene (CF2[double bond, length as m-dash]CF–CH2F) reaction with Cl-atoms and subsequent aerial degradation of its product radicals in the presence of NO

Abstract

To give a comprehensive account of the environmental acceptability of 1,1,2,3-tetrafluoropropene (CF2[double bond, length as m-dash]CF–CH2F) in the troposphere, we have examined the oxidation reaction pathways and kinetics of CF2[double bond, length as m-dash]CF–CH2F initiated by Cl-atoms using the second-order Møller–Plesset perturbation (MP2) theory along with the 6-31+G(d,p) basis set. We also performed single-point energy calculations to further refine the energies at the CCSD(T) level along with the basis sets 6-31+G(d,p) and 6-311++G(d,p). The estimation of the relative energies and thermodynamic parameters of the CF2[double bond, length as m-dash]CF–CH2F + Cl reaction clearly shows that Cl-atom addition reaction pathways are more dominant compared to H-abstraction reaction pathways. The value of the rate coefficient for each reaction channel is calculated using the conventional transition state theory (TST) over the temperature range of 200–1000 K at 1 atm. The estimated overall rate coefficients for the title reaction are found to be 1.10 × 10−12, 1.21 × 10−10, and 1.13 × 10−8 cm3 per molecule per s via the respective calculation methods viz. MP2/6-31+G(d,p), CCSD(T)//MP2/6-31+G(d,p), and CCSD(T)/6-311++G(d,p)//MP2/6-31+G(d,p), at 298.15 K. Moreover, the calculated rate coefficients and percentage branching ratio values suggest that the Cl-atom addition reaction at the β-carbon atom is more preferable to that of the α-carbon addition to CF2[double bond, length as m-dash]CF–CH2F. Based on the rate coefficient values calculated by the three different methods, the atmospheric lifetime for the title reaction at 298.15 K is estimated. The radiative efficiency (RE) and Global Warming Potential (GWP) results of the title molecule show that its GWP would be negligible. Further, we have explored the degradation of its product radicals in the presence of O2 and NO. From the degradation results, we have found that CF2(Cl)COF, FCOCH2F, FCFO and FCOCl are formed as stable end products along with various radicals such as ˙CF2Cl and ˙CH2F. Therefore, these findings of kinetic and mechanistic data can be applied to the development and implementation of a novel CFC replacement.

Graphical abstract: Oxidation pathways and kinetics of the 1,1,2,3-tetrafluoropropene (CF2 [[double bond, length as m-dash]] CF–CH2F) reaction with Cl-atoms and subsequent aerial degradation of its product radicals in the presence of NO

Supplementary files

Article information

Article type
Paper
Submitted
07 Des 2023
Accepted
13 Feb 2024
First published
16 Feb 2024

Environ. Sci.: Processes Impacts, 2024,26, 734-750

Oxidation pathways and kinetics of the 1,1,2,3-tetrafluoropropene (CF2[double bond, length as m-dash]CF–CH2F) reaction with Cl-atoms and subsequent aerial degradation of its product radicals in the presence of NO

U. P. Kakati, D. Dowerah, R. C. Deka, N. K. Gour and S. Paul, Environ. Sci.: Processes Impacts, 2024, 26, 734 DOI: 10.1039/D3EM00545C

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