RRKM Theory, the CH3NC Paradox, and the Decomposition of Hot-Atom Substitution Products

``Paradox'' and ``contrary to RRKM predictions'' are descriptions that have been applied to secondary unimolecular reactions following hot‐atom substitution. These processes are strongly influenced by rotational effects which have until now been ignored. The crudest theoretical construction suffices to account for the curious behavior of CH₂TNC in terms of a reasonable (sharply peaked, high energy) excitation function for T‐for‐H substitution. The reactions of vibrationally energized ${\mathrm{CH}}_3{\mathrm{CF}}_2^{18}\mathrm{F}\mathrm{,\hspace{0.17em}}{\mathrm{CH}}_2^{18}{\mathrm{FCF}}_3,$ and CH₃T can also be interpreted, with plausible critical configurations and excitation functions.