The gas phase reaction of CF 3 radicals with C 6 F 5 H in the temperature range 373–658 K

CF 3 radicals were generated by the photolysis of perfluoroacetic anhydride. In the presence of pentafluorobenzene, the CF 3 radicals react according to the following mechanism:It was found that the addition reaction (3) becomes reversible above ca. 453 K. The addition rate parameters have been revised and they satisfactorily agree with those reported previously. At temperatures higher than 593 K, only true H‐abstraction occurs. The rate constant k H for reaction (5) is given by:\documentclass{article}\pagestyle{empty}\begin{document}$$ \log [(k_{\rm H} /k_c^{1/2}){\rm mol}^{- 1/2} \,{\rm cm}^{{\rm 3/2}} \,{\rm s}^{{\rm - 1/2}}]\, = \,(4.34\, \pm \,0.43)\, - \,(59,00\, \pm \,2.62)/\theta $$\end{document}where θ = 2.303 RT kJmol −1 and k c is the rate constant for combination of CF 3 radicals. The reactions of CF 3 with benzene and pentafluorobenzene are compared.