ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The reaction of methyl radicals (Me) with hexafluoroacetone (HFA), generated from ditertiary butyl peroxide (dtBP), was studied over the temperature range of 402-433 K and the pressure range of 38-111 torr. The reaction resulted in the following displacement process taking place: where TFA refers to trifluoroacetone. The trifluoromethyl radicals that were generated abstract a hydrogen atom from the peroxide: such that k6a is given by: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}\,\,k_{6{\rm a}} \left( {M^{ - 1} \cdot {\rm s}^{ - 1} } \right)\,\, = \,\,8.2\, \pm \,0.7\, - \,8.9\, \pm \,{{1.3} \mathord{\left/ {\vphantom {{1.3} \theta }} \right. \kern-\nulldelimiterspace} \theta } $$\end{document} where θ = 2.303RT kcal/mol. The interaction of methyl and trifluoromethyl radicals results in the following steps: Product analysis shows that k17/k151/2k161/2 = 2.0 ± 0.2 such that k17 = 1010.4±0.5M-1 · s-1. The rate constant k5 is given by: \documentclass{article}\pagestyle{empty}\begin{document}$$ {{{\rm log}\,\,k_5 } \mathord{\left/ {\vphantom {{{\rm log}\,\,k_5 } {\left( {M^{ - 1} \cdot {\rm s}^{ - 1} } \right)}}} \right. \kern-\nulldelimiterspace} {\left( {M^{ - 1} \cdot {\rm s}^{ - 1} } \right)}}\,\, = \,\,8.0\, \pm \,1.3\, - \,5.1\, \pm \,{{0.7} \mathord{\left/ {\vphantom {{0.7} \theta }} \right. \kern-\nulldelimiterspace} \theta } $$\end{document} It is concluded that the preexponential factor for the addition of methyl radicals to ketones is lower than that for the addition of methyl radicals to olefins.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550160509
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