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Kinetics of the thermal isomerization of 1,1,2,2‐tetramethylcyclopropane
Author(s) -
Lewis David K.,
Gray Timothy,
Katsva Vlad,
Parcella Kyle,
Schlier Jessica,
Kalra Bansi L.,
Cho Janet,
Mish Debra
Publication year - 2006
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.20149
Subject(s) - isomerization , chemistry , arrhenius equation , kinetics , cyclopropane , shock tube , atmospheric temperature range , activation energy , thermodynamics , analytical chemistry (journal) , medicinal chemistry , organic chemistry , catalysis , shock wave , physics , ring (chemistry) , quantum mechanics
Reaction rates for the structural isomerization of 1,1,2,2‐tetramethylcyclopropane to 2,4‐dimethyl‐2‐pentene have been measured over a wide temperature range, 672–750 K in a static reactor and 1000–1120 K in a single‐pulse shock tube. The combined data from the two temperature regions give Arrhenius parameters E a =64.7 (±0.5) kcal/mol and log 10 ( A , s −1 ) = 15.47 (±0.13). These values lie at the upper end of the ranges of E a and log A values (62.2–64.7 kcal/mol and 14.82–15.55, respectively) obtained from three previous experimental studies, each of which covered a narrower temperature range. The previously noted trend toward lower E a values for structural isomerization of methylcyclopropanes as methyl substitution increases extends only through the dimethylcyclopropanes (1,1‐ and 1,2‐); E a then appears to increase with further methyl substitution. In contrast, the pre‐exponential factors for isomerization of cyclopropane and all of the methylcyclopropanes through tetramethylcyclopropane lie within ±0.3 of log 10 ( A , s −1 ) = 15.2 and show no particular trend with increasing substitution. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 483–488, 2006