Thermal stability of cyclohexane and 1‐hexene

The mechanism and initial rates of decomposition of cyclohexane and 1‐hexene have been determined from single‐pulse shock‐tube experiments. The main initial processes involve isomerization of cyclohexane to 1‐hexene, followed by decomposition of 1‐hexene. From comparative rate experiments the following rate expressions have been derived:\documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm cyclohexane} \to 1 - {\rm hexene}) = 10^{16.7} \exp (- 44,400/T)\,\,\sec ^{- 1} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ k_B (1 - {\rm hexene} \to {\rm C}_{\rm 3} {\rm H}_{{\rm 5}} \cdot {\rm + nC}_{\rm 3} {\rm H}_{{\rm 7}} \cdot) = 10^{15.9} \exp (- 35,600/T)\,\,\sec ^{- 1} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ k_{\rm M} (1 - {\rm hexene} \to 2{\rm C}_{\rm 3} {\rm H}_6) = 10^{12.6} \exp (- 28,900/T)\,\,\sec ^{- 1} $$\end{document}The 1‐hexene bond‐braking reaction leads to an allylic resonance energy of 42.7 kJ and a heat of formation of allyl radicals of 176.6 kJ (300°K). There appear to be general relations relating the rate expressions for the decomposition of alkynes, alkanes, and alkenes. Studies on the induced decomposition of cyclohexane have also been carried out.