Understanding halogen‐substituent assistance in H‐atom abstraction‐based reactions of CHCl•− with CH4 − nXn (X = H,F, Cl; n = 0–3) |
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| Authors: | Liang Junxi Li Yu Zhang Qiang Geng Zhiyuan |
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| Institution: | 1. College of Chemical Engineering, Northwest University for Nationalities, , Lanzhou, Gansu, 730030 China;2. Institute of Arid Meteorology, CMA;3. Key laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province;4. Key Open Laboratory of Arid Climatic Change and Disaster Reduction of CMA, , Lanzhou, 730020 China;5. Gansu Key Laboratory of Polymer Materials, College of Chemistry and Chemical Engineering, Key Laboratory of Eco‐environment‐related Polymer Materials;6. Ministry of Education, Northwest Normal University, , Lanzhou, Gansu, 730070 China |
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| Abstract: | The effect of halogen‐substituent on hydrogen abstraction mechanisms was studied by applying density functional theory functional calculations to the gas‐phase reactions between CHCl?? and CH4 ? nXn (X = H, F, Cl; n = 0–3), and it is found that a heavier X substituent in the substrate results in a greater stabilization of corresponding complex, a lower activation energy, a faster H‐abstraction reaction, and greater exothermicity. However, CH4– reaction is more reactive than CH3F– reaction under the same condition because of dominant π‐donation from the electronegative F atom. We also explored the reactivity difference for the seven reactions in terms of factors derived from bond order, second‐order perturbative energy, and activation strain model analysis. The rate constants are evaluated over a wide temperature range of 298–1000 K by the conventional transition state theory. Copyright © 2014 John Wiley & Sons, Ltd. |
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| Keywords: | carbene radical anion density functional theory (DFT) H abstraction |
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