Computational Study of the Reactions of Chlorine Radicals with Atmospheric Organic Compounds Featuring NHx-π-Bond (x = 1, 2) Structures.
Among 160 organic NHx-containing compounds (x = 1, 2) detected in the atmosphere, there are about 80 species for which the molecules contain p-π conjugate substructures of NHx-π-bonds. Here, chlorine radical (·Cl)-initiated reactions for formamide, N-methylformamide, ethenamine, and aniline, as their cases, were investigated by a quantum chemical method [CCSD(T)/aug-cc-pVTZ//MP2/6-31+G(3df,2p)] and kinetics modeling. The calculated overall rate constants are 5.5 × 10-11, 2.3 × 10-10, 2.7 × 10-10, and 1.7 × 10-10cm3molecule-1s-1for formamide, N-methylformamide, ethenamine, and aniline, respectively, and agree well with experimental values for available ones. Importantly, the results show that the reactions of two amides with ·Cl mainly lead to C-center radicals via ·Cl abstracting the -CHO hydrogen of amides. However, both ethenamine + ·Cl and aniline + ·Cl reactions mainly produce delocalized radicals with the radical center on the C-site and N-site via a ·Cl addition and the -NHxhydrogen abstraction pathway, respectively. Therefore, this study reveals that reactions of organic NHx-containing compounds with ·Cl have various reaction mechanisms, in contrast to our previous understanding that -NHxhydrogen abstraction pathways, leading to N-center radicals, are the most favorable. The unveiled reaction mechanisms should be of significance for the risk assessment of atmospheric organic NHx-containing compounds and enriching ·Cl chemistry.
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116024, China.
Hong-Bin
http://orcid.org/0000-0002-9119-9785
HB
Xie
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116024, China.
Fangfang
F
Ma
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116024, China.
Qi
Q
Yu
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116024, China.
Ning
N
He
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116024, China.
Jingwen
http://orcid.org/0000-0002-5756-3336
J
Chen