The homogeneous pyrolysis of 2‐butenes

The homogeneous pyrolysis of 2‐butene subjected to shock heating was studied in the limit of high pressures by a relative rate technique. Over the temperature range of 1150–1325°K nearly equal amounts of methane, propylene, and butadiene were formed starting with either the cis‐ or trans ‐2‐butene, while isomerization remained far from equilibrium. The results are consistent with a simple free radical mechanism for which we find\documentclass{article}\pagestyle{empty}\begin{document}$$ k^\infty [{\rm C}_4 {\rm H}_8 \mathop \rightarrow\limits_{cis} {\rm CH}_3 + {\rm C}_3{\rm H}_5] = 10^{16} \exp (-80,000/RT)\sec^{-1} $$\end{document} as the initial rate‐limiting step.