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Understanding halogen‐substituent assistance in H‐atom abstraction‐based reactions of CHCl •− with CH 4 − n X n (X = H, F, Cl; n = 0–3)
Author(s) -
Junxi Liang,
Yu Li,
Qiang Zhang,
Zhiyuan Geng
Publication year - 2014
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.3276
Subject(s) - chemistry , substituent , halogen , reactivity (psychology) , hydrogen atom abstraction , density functional theory , hydrogen atom , activation energy , transition state theory , medicinal chemistry , reaction rate constant , atom (system on chip) , computational chemistry , hydrogen , kinetics , organic chemistry , group (periodic table) , alkyl , medicine , alternative medicine , physics , pathology , quantum mechanics , computer science , embedded system
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 CH 4 − n X n (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, CH 4 – reaction is more reactive than CH 3 F– 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.