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. C 2006
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.