Pyrolysis of acetylene‐vinylacetylene mixtures between 400 and 500°C

Acetylene and vinylacetylene mixtures were pyrolyzed at 400‐500°C in the absence and presence of O 2 or NO. The major product of the interaction between C 2 H 2 and C 4 H 4 is polymer, but benzene is also produced. Both the C 2 H 2 removal and C 6 H 6 formation rates arefirst‐order in C 2 H 2 and C 4 H 4 . The rate coefficients are\documentclass{article}\pagestyle{empty}\begin{document}$$ \log (k\{ {\rm C}_{\rm 2} {\rm H}_{\rm 2} \}, M^{ - 1} {\rm s}^{{\rm - 1}}) = 6.26 \pm 0.20 - (70.6 \pm 3.6)/2.3RT $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ \log (k\{ {\rm C}_{\rm 6} {\rm H}_{\rm 6} \}, M^{ - 1} {\rm s}^{{\rm - 1}}) = 8.65 \pm 0.39 - (125.9 \pm 5.4)/2.3RT $$\end{document}where R is the ideal gas constant in kJ/mol‐K. Benzene formation occurs by two processes: a concerted molecular mechanism (≃60%) and a singlet diradical mechanism (≃40%).