Kinetics of the thermal isomerization of 1,1,2,2-tetramethylcyclopropane

✍ Scribed by David K. Lewis; Timothy Gray; Vlad Katsva; Kyle Parcella; Jessica Schlier; Bansi L. Kalra; Janet Cho; Debra Mish

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 119 KB
• Volume: 38
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20149

✦ Synopsis

Abstract

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