Chemistry of nuclear recoil¹⁸F Atoms. IV. Hot F-to-HF and F-to-F₂ abstraction in CH₃CF₃

New hot abstraction reaction channels have been demonstrated for nuclear recoil ¹⁸F atoms reacting with fluorocarbon substrates. Hot F-to-HF abstraction in CH₃CF₃ is a very efficient process with an absolute hot yield of 51%±3%. Hot F-to-F₂ reactions also occur, but with much lower efficiencies. The F-to-F₂ absolute hot yields in CH₃CF₃, C₂F₆, and C ₃F₆ are 5.4%±0.3%, 6.9%±0.8%, and 11.7%±0.5%, respectively. In good agreement with theoretical expectations, translational excitation appears to be much more effective as a driving force for the exoergic F-to-HF process in comparison with the endoergic F-to-F₂ process. The Arrhenius activation energy for thermal F-to-HF abstraction in CH₃CF₃ is at least 2.1±0.1 kcal/mole larger than the value associated with the thermal ¹⁸F-atom pi-addition process in C₂F₆.