Unimolecular Rate Constants for Chemically Activated 1,1,1-Trifluoro-2-chloroethane: A Competitive Three-Channel System

Article abstract of DOI:10.1021/j100163a016

Chemically activated CF3CH2Cl was prepared with 97.5 kcal/mol of internal energy by the combination of CF3 and CH2Cl radicals.The total unimolecular decomposition rate constant was measured by using two internal standard methods and the average was (7.5 +/- ^2.6_1.5) * 10⁶ s^-1.The rate constant for four-centered elimination of HF was measured as (2.8 +/- 0.1) * 10⁶ s^-1, for C-Cl bond homolysis the rate constant was (0.8 +/- ^5.6_0.1) * 10⁶ s^-1, and by difference the three-centered HCl elimination rate constant was (3.9 +/- ^2.6_3.0) * 10⁶ s^-1.These rate constants were compared to predictions from RRKM theory, and threshold energies were assigned for loss of HF (76 kcal/mol), for C-Cl-bond rupture (83 kcal/mol), and for HCl elimination (72 kcal/mol).Product distributions from three activation methods (chemical, multiphoton laser, and thermal) were analyzed to develop a self-consistent view of this complex reaction system.