The oxidation mechanism and kinetics of limononic acid by hydroxyl radical in atmospheric aqueous phase
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The oxidation mechanism and kinetics of limononic acid by hydroxyl radical in atmospheric aqueous phase. / Chen, Yanqi; Lv, Guochun; Wang, Yan; Li, Xiaofan; Sun, Juan; Zhou, Xuehua; Sun, Xiaomin.
In: Atmospheric Environment, Vol. 294, 119527, 2023.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - The oxidation mechanism and kinetics of limononic acid by hydroxyl radical in atmospheric aqueous phase
AU - Chen, Yanqi
AU - Lv, Guochun
AU - Wang, Yan
AU - Li, Xiaofan
AU - Sun, Juan
AU - Zhou, Xuehua
AU - Sun, Xiaomin
N1 - Publisher Copyright: © 2022 Elsevier Ltd
PY - 2023
Y1 - 2023
N2 - Limononic acid (3-isopropenyl-6-oxoheptanoic acid, LA), as an important precursor of secondary organic aerosols (SOA), has attracted extensive attention in the field of atmospheric chemistry. However, its microscopic oxidation mechanism is still unclear. In this study, the density functional theory calculations were conducted to study the oxidation mechanism of LA by ·OH in aqueous phase. The results show that the reactions of hydroxylation are more likely to occur than the dehydrogenation reaction, because of the lower free energy barrier (2.3–5.4 kcal mol−1). At 298 K, the total rate constant of the reaction initiated by ·OH is 1.06 × 1010 M−1 s−1, which fits the experimental value well. Among all reactions, the hydroxylation reaction in C9 site of LA is the most favorable pathway, and the corresponding hydroxylation intermediate (IM4) can react with ·OH, H2O, dissolved O2, and HO2·. Three important tropospheric free radicals (R·, RO· and RO2·) are generated during the subsequent reaction process. Meanwhile alcohols, ketones, aldehydes, and oxidized acids can be formed in the overall reaction scheme. These products are the precursor for the formation of SOA, and this transformation process will increase the O/C ratio of aqueous phase SOA. This study has an important significance for understanding the oxidation mechanism of monoterpenoids in the atmospheric aqueous phase.
AB - Limononic acid (3-isopropenyl-6-oxoheptanoic acid, LA), as an important precursor of secondary organic aerosols (SOA), has attracted extensive attention in the field of atmospheric chemistry. However, its microscopic oxidation mechanism is still unclear. In this study, the density functional theory calculations were conducted to study the oxidation mechanism of LA by ·OH in aqueous phase. The results show that the reactions of hydroxylation are more likely to occur than the dehydrogenation reaction, because of the lower free energy barrier (2.3–5.4 kcal mol−1). At 298 K, the total rate constant of the reaction initiated by ·OH is 1.06 × 1010 M−1 s−1, which fits the experimental value well. Among all reactions, the hydroxylation reaction in C9 site of LA is the most favorable pathway, and the corresponding hydroxylation intermediate (IM4) can react with ·OH, H2O, dissolved O2, and HO2·. Three important tropospheric free radicals (R·, RO· and RO2·) are generated during the subsequent reaction process. Meanwhile alcohols, ketones, aldehydes, and oxidized acids can be formed in the overall reaction scheme. These products are the precursor for the formation of SOA, and this transformation process will increase the O/C ratio of aqueous phase SOA. This study has an important significance for understanding the oxidation mechanism of monoterpenoids in the atmospheric aqueous phase.
KW - DFT calculation
KW - Kinetics analysis
KW - Limononic acid
KW - OH radical
KW - Transformation mechanism
U2 - 10.1016/j.atmosenv.2022.119527
DO - 10.1016/j.atmosenv.2022.119527
M3 - Journal article
AN - SCOPUS:85143345070
VL - 294
JO - Atmospheric Environment
JF - Atmospheric Environment
SN - 1352-2310
M1 - 119527
ER -
ID: 339333910