Kinetics of the thermal dimerization and isomerization of cis, trans-1,5-cyclooctadiene in the gas phase and of related reactions. A simple algorithm to determine the rate constants of competing first- and second-order reactions
✍ Scribed by J. Leitich
- Publisher
- John Wiley and Sons
- Year
- 1979
- Tongue
- English
- Weight
- 687 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
Abstract
In the gas phase, cis,trans‐1,5‐cyclooctadiene (\documentclass{article}\pagestyle{empty}\begin{document}$ {\mathop 1\limits_\sim} $\end{document}) undergoes a unimolecular rearrangement to cis,cis‐1,5‐cyclooctadiene (\documentclass{article}\pagestyle{empty}\begin{document}$ {\mathop 2\limits_\sim} $\end{document}) and bimolecular formation of dimers \documentclass{article}\pagestyle{empty}\begin{document}$ {\mathop 3\limits_\sim}-{\mathop 5\limits_\sim} $\end{document} $\end{document}. The Arrhenius parameters are E~A~ = 135.7 ± 4.4 kJ mole^−1^ and log(A/sec^−1^) = 12.9 ± 0.6 for the first reaction and E~A~ = 66.1 ± 6.0 kJ mole^−1^ and log[A/(liter mole^−1^ sec^−1^)] = 5.5 ± 0.8 for the second reaction. Using thermochemical kinetics, the first reaction is shown to proceed via a rate determining Cope rearrangement of \documentclass{article}\pagestyle{empty}\begin{document}$ {\mathop 1\limits_\sim} $\end{document} to __cis__1,2‐divinylcyclobutane (\documentclass{article}\pagestyle{empty}\begin{document}$ {\mathop 6\limits_\sim} $\end{document}), E~A~ = 136.2 ‐ 4.4 kJ mole^−1^ and log(A/sec^−1^) = 13.0 ± 0.6. The corresponding back reaction, \documentclass{article}\pagestyle{empty}\begin{document}$ {\mathop 6\limits_\sim}{\rightarrow}{\mathop 1\limits_\sim} $\end{document}, which was investigated separately, shows E~A~ = 110.2 ± 1.2 kJ mole^−1^ and log(A/sec^−1^) = 10.9 ± 0.2. The heat of formation of \documentclass{article}\pagestyle{empty}\begin{document}$ {\mathop 6\limits_\sim} $\end{document} is determined to 188 ± 5.5 kJ mole^−1^. The mechanism of formation of dimers \documentclass{article}\pagestyle{empty}\begin{document}$ {\mathop 3\limits_\sim}-{\mathop 5\limits_\sim} $\end{document} is discussed. To allow the formal analysis of the kinetic problem, a simple algorithm to obtain the rate constants of competing first‐ and second‐order reactions was developed.