Cl‐atom transfer from CFCl 3 to the c ‐C 6 H 11 radical. An indirect estimation of the CFCl 2 Cl bond dissociation energy

The Cl‐transfer reaction between CFCl 3 and c ‐C 6 H 11 radicals (R) was studied in liquid cyclohexane (RH). The Arrhenius parameters for Cl abstraction were determined in the RH‐CFCl 3 system versus the termination reaction between cyclohexyl radicals and competitively versus addition to C 2 Cl 4 in the RH‐CFCl 3 ‐C 2 Cl 4 system. The two sets of results are in very good agreement and give the following Arrhenius expression for the reaction R + CFCL 3 → RCl + CFCl 2 (2):\documentclass{article}\pagestyle{empty}\begin{document}$$ \log {\rm }k_2 (1/{\rm mol\, sec}) = 8.95 - 7.79/\theta $$\end{document}where θ = 2.303 RT in kcal/mol. Comparison with Cl‐transfer data of other chloromethanes and chloroethanes shows that an increase in the CCl bond dissociation energy is the main cause of the reduced reactivity of CFCl 3 . Based on a previously developed correlation, D (CFCl 2 Cl) is estimated to be equal to 74.4 kcal/mol.