Issue 4, 2024

New insights into the mechanism and kinetics of the addition reaction of unsaturated Criegee intermediates to CF3COOH and tropospheric implications

Abstract

In this work, we have investigated the mechanism, thermochemistry and kinetics of the reaction of syncis-CH2[double bond, length as m-dash]RzCRyC[double bond, length as m-dash]O+O (where Rz, Ry = H, CH3–) unsaturated Criegee intermediates (CIs) with CF3COOH using quantum chemical methods. The rate coefficients for the barrierless reactions were calculated using variable reaction coordinate variational transition state theory (VRC-VTST). For the syncis-CH2[double bond, length as m-dash]RzCRyC[double bond, length as m-dash]O+O conformation in which conjugated C[double bond, length as m-dash]C and C[double bond, length as m-dash]O double bonds are aligned with each other, we propose a new pathway for the unidirectional addition of an O[double bond, length as m-dash]C–OH molecule (CF3COOH) to the C[double bond, length as m-dash]C double bond of syncis-CH2[double bond, length as m-dash]RzCRyC[double bond, length as m-dash]O+O. The rate coefficient for the 1,4-C[double bond, length as m-dash]C addition reaction at 298 K is ∼10−10 to 10−11 cm3 s−1, resulting in the formation of CF3C(O)OCH2CRz[double bond, length as m-dash]RyCOOH trifluoroacetate alkyl allyl hydroperoxide (TFAAAH) as a new transitory adduct. It can act as a precursor for the formation of secondary organic aerosols (SOAs). This novel TFAAAH hydroperoxide was identified through a detailed quantum chemical study of the 1,4-addition mechanism and will provide new insights into the significance of the 1,4-addition reaction of unsaturated Cls with trace tropospheric gases on –CRz[double bond, length as m-dash]CH2 vinyl carbon atoms.

Graphical abstract: New insights into the mechanism and kinetics of the addition reaction of unsaturated Criegee intermediates to CF3COOH and tropospheric implications

Supplementary files

Article information

Article type
Paper
Submitted
13 déc. 2023
Accepted
15 févr. 2024
First published
16 févr. 2024

Environ. Sci.: Processes Impacts, 2024,26, 751-764

New insights into the mechanism and kinetics of the addition reaction of unsaturated Criegee intermediates to CF3COOH and tropospheric implications

M. Lily, X. Lv, A. K. Chandra, N. Tsona Tchinda and L. Du, Environ. Sci.: Processes Impacts, 2024, 26, 751 DOI: 10.1039/D3EM00554B

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