ISSN:
0538-8068
Schlagwort(e):
Chemistry
;
Physics Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
A check of the data from comparative rate single-pulse shock tube experiments have been carried out through the use of a new standard reaction, the decyclization reaction of ethylcyclobutane. The rate expressions for cyclohexene and 2,2,3-trimethylbutane have been found to be \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} k({\rm C}_{\rm 6} {\rm H}_{{\rm 10}} \to 1,3 - {\rm C}_4 {\rm H}_6 + {\rm C}_2 {\rm H}_4 ) = 10^{15.3} \exp ( - 33,690/T)\sec ^{ - 1} ,950^ \circ - 1100^ \circ {\rm K,2} - {\rm 6atm} \\ k(t{\rm C}_4 {\rm H}_9 - {\rm iC}_3 {\rm H}_7 \to t{\rm C}_{\rm 4} {\rm H}_{\rm 9} \cdot + {\rm iC}_{\rm 3} {\rm H}_7 \cdot ) = 10^{16.5} {{\exp ( - 36,830} \mathord{\left/ {\vphantom {{\exp ( - 36,830} T}} \right. \kern-\nulldelimiterspace} T})\sec ^{ - 1} ,1000^ \circ - 1100^ \circ {\rm K,2} - {\rm 6atm} \\ \end{array} $$\end{document} in excellent agreement with previously published results. Most of the small discrepancy that does exist is apparently due to the differences between the present and earlier (decomposition of isopropyl bromide) "standard" reaction. For the latter process, the present study yields \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm iC}_{\rm 3} {\rm H}_7 {\rm Br} \to {\rm C}_{\rm 3} {\rm H}_6 + {\rm HBr}) \to 10^{13.73} {\rm exp(}{{ - 23,970} \mathord{\left/ {\vphantom {{ - 23,970} {T\sec ^{ - 1} ,800^ \circ - 1000^ \circ {\rm K,2} - {\rm 6}}}} \right. \kern-\nulldelimiterspace} {T\sec ^{ - 1} ,800^ \circ - 1000^ \circ {\rm K,2} - {\rm 6}}}{\rm atm)} $$\end{document} These results confirm the correctness of previously published comparative rate single-pulse shock tube experiments. They demonstrate once again that for the decomposition of paraffin hydrocarbons, calculated preexponential factors are at least an order of magnitude higher than the directly measured number and that the accepted value of the heat of formation of t-butyl radicals ΔHf300(tC4H9·) = 29 kJ (6.8 kcals) is at least 10 kJ too low. Finally, attention is called to recent studies on neopentane decomposition in flow and static systems which are in complete agreement with the present conclusions.
Zusätzliches Material:
3 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/kin.550020406
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