ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The static vessel pyrolysis of bicyclo[2.2.2]octa-2,5,7-triene (barrelene) has been studied between 483 and 523 K. The products were acetylene and benzene (in equal quantities) with no other detectable C8H8 isomer (down to less than 1% of total). The time dependence fitted first-order kinetics, and the data are consistent with a homogeneous unimolecular reaction close to, if not at, its high-pressure limit at 0.25 torr. The rate constant was fitted to the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \log \left( {{k \mathord{\left/ {\vphantom {k {s^{ - 1} }}} \right. \kern-\nulldelimiterspace} {s^{ - 1} }}} \right)\, = \,\left( {14.27\, \pm \,0.18} \right)\, - \,{{\left( {41.71\, \pm \,0.41\,{{{\rm kcal}} \mathord{\left/ {\vphantom {{{\rm kcal}} {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}} \right)} \mathord{\left/ {\vphantom {{\left( {41.71\, \pm \,0.41\,{{{\rm kcal}} \mathord{\left/ {\vphantom {{{\rm kcal}} {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}} \right)} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}\,\ln \,10 $$\end{document} These Arrhenius parameters are shown to imply a concerted single-step process. Alternative mechanisms are discussed and a comparison is made with the retro-Diels - Alder reactions of other bicyclo[2.2.2]octa-olefin systems.
Additional Material:
4 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550160204
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