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Kinetics of the thermal decomposition of CF 3 CHCL 2 in a single‐pulse shock tube
Author(s) -
Sekhar M. V. C.,
Millward G. E.,
TschuikowRoux E.
Publication year - 1973
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.550050307
Subject(s) - chemistry , shock tube , thermal decomposition , kinetics , reaction rate constant , pyrolysis , atmospheric temperature range , decomposition , torr , shock (circulatory) , bond cleavage , hydrogen fluoride , thermodynamics , analytical chemistry (journal) , inorganic chemistry , organic chemistry , shock wave , catalysis , medicine , physics , quantum mechanics
The pyrolysis of 2,2‐dichloro‐1,1,1‐trifluoroethane was studied over the temperature range of 1120–1260°K at total reflected shock pressures from ∼2800 to 3100 torr. Below 1260°K, the decomposition leads to three reaction products which were identified as CF 2 CFCl, CF 2 CFH, and CF 3 CCl 3 . The results are interpreted in terms of a parallel CCl bond rupture process which becomes competitive with the molecular HCI elimination. The rate constant for the α,α‐elimination process\documentclass{article}\pagestyle{empty}\begin{document}$$ CF_3 CHCl_2 \to CF_2 CFCl + HCL $$\end{document}has been deduced to be\documentclass{article}\pagestyle{empty}\begin{document}$$ \log \left( {K_1 ^\infty /\sec ^{ - 1} } \right) = \left( {13.4 \pm 0.7} \right) - \left( {63.1 \pm 3.8kcal} \right)/2.303RT $$\end{document}It was also possible to obtain the overall rate constant for the formation of CF 2 CFH, which is given by\documentclass{article}\pagestyle{empty}\begin{document}$$ \log \left( {K^{''} /\sec ^{ - 1} } \right) = \left( {11.5 \pm 0.8} \right) - \left( {54.1 \pm 3.8kcal} \right)/2.303RT $$\end{document}Some evidence for hydrogen fluoride elimination was found at temperatures above 1260°K. However, at these higher temperatures CC bond scission also occurs and the kinetics of the system become untractable.