Thermische Zerfallsreaktionen von Nitroverbindungen in Stosswellen. II: Dissoziation von Nitroäthan

A shock wave study of the thermal decomposition of nitroethane in excess Ar at temperatures 900 < T < 1350 K and total concentrations of 4,5 · 10 −6 < [Ar] < 3 · 10 −4 mol cm −3 showed that the CN‐bond fission\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 2} {\rm H}_{\rm 5} {\rm NO}_{\rm 2} (+ {\rm M}) \to {\rm C}_{\rm 2} {\rm H}_{\rm 5} {\rm + NO}_{\rm 2} (+ {\rm M}) $$\end{document}is the primary reaction step. This unimolecular reaction could be observed in its transition region near the high pressure limit. The derived rate constants are k ∞ = 10 15.9 exp (–57 kcal mol −1 /RT) s −1 for the high pressure and k 0 /[Ar] = 10 18.0 exp (‐36 kcal mol −1 /RT) cm 3 mol −1 s −1 (at T ≃ 1100–1200 K) for the low pressure limit. The observed concentration profiles of C 2 H 5 NO 2 and NO 2 permitted to conclude on the subsequent decomposition of the ethyl radical\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 2} {\rm H}_{\rm 5} (+ {\rm M}) \to {\rm C}_{\rm 2} {\rm H}_{\rm 4} {\rm + H}(+ {\rm M}) $$\end{document}This reaction was found to be in the fall‐off range under the applied conditions.