Reaction of CF 3 radicals with H 2 S

Hydrogen abstration from H 2 S by CF 3 radicals, generated by the photolysis of both CF 3 COCF 3 and CF 3 I, has been studied in the temperature range 314–434 K. The rate constant, based on the value of 10 13.36 cm 3 /mol · s for the recombination of CF 3 radicals, is given by\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log }\,k_2 \, = \,\left( {12.20\, \pm \,0.05} \right)\, - \,{{\left( {19,220\, \pm \,360} \right)} \mathord{\left/ {\vphantom {{\left( {19,220\, \pm \,360} \right)} {19.145T}}} \right. \kern-\nulldelimiterspace} {19.145T}} $$\end{document}with CF 3 COCF 3 as the radical source, and\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log }\,k_2 \, = \,\left( {12.00\, \pm \,0.07} \right)\, - \,{{\left( {18,270\, \pm \,470} \right)} \mathord{\left/ {\vphantom {{\left( {18,270\, \pm \,470} \right)} {19.145T}}} \right. \kern-\nulldelimiterspace} {19.145T}} $$\end{document}with CF 3 I as the radical source, where k 2 is in cm 3 /mol · s and E is in J/mol. These results resolve a previously existing controversy concerning the values of the rate constants for this reaction. They show that CF 3 radicals are less reactive than CH 3 radicals in attacking H 2 S, and this behavior indicates that polar effects play a significant role in the hydrogen transfer reactions of CF 3 radicals.