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Comparative rate single‐pulse shock tube studies on the thermal decomposition of cyclohexene, 2,2,3‐trimethylbutane, isopropyl bromide, and ethylcyclobutane
Author(s) -
Tsang Wing
Publication year - 1970
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550020406
Subject(s) - chemistry , thermal decomposition , bromide , shock tube , decomposition , cyclohexene , thermodynamics , neopentane , radical , shock (circulatory) , analytical chemistry (journal) , organic chemistry , shock wave , catalysis , medicine , physics , molecule
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 Δ H f300 ( t C 4 H 9 ·) = 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.