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Kinetics of the reaction of C 6 H 5 with HBr and DBr
Author(s) -
Yu T.,
Lin M. C.
Publication year - 1994
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550260711
Subject(s) - chemistry , reaction rate constant , kinetics , alkyl , atmospheric temperature range , ring (chemistry) , negative temperature , polar effect , medicinal chemistry , photochemistry , thermodynamics , organic chemistry , physics , quantum mechanics
Abstract The rate constants for the reaction of C 6 H 5 with HBr and DBr have been measured with the cavity–ring–down method in the temperature range of 297 to 523 K and 297 to 500 K, respectively. These rate constants can be effectively represented, in units of cm 3 /s, by\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} k_{{\rm HBr}} = 10^{- 10.40 \pm 0.24} \exp \left[{{{\left({- 554 \pm 208} \right)} \mathord{\left/ {\vphantom {{\left({- 554 \pm 208} \right)} T}} \right. \kern-\nulldelimiterspace} T}} \right]{\rm and} \\ k_{{\rm DBr}} = 10^{- 10.36 \pm 0.17} \exp \left[{{{\left({- 662 \pm 151} \right)} \mathord{\left/ {\vphantom {{\left({- 662 \pm 151} \right)} T}} \right. \kern-\nulldelimiterspace} T}} \right]{\rm.} \\ \end{array} $$\end{document}Both activation energies are similar and positive, contrary to those of alkyl radical reactions, all of which exhibit negative temperature dependencies. The difference, as pointed out before [1], could be accounted for by the electron‐withdrawing effect of the phenyl vis‐à‐vis the electron‐donating ability of the alkyls. © 1994 John Wiley & Sons, Inc.