Decomposition of 1,1,2,2-tetrafluorocyclopropane. Arrhenius parameters and their influence on the chemical activation results

The kinetics of the gas-phase thermal decomposition of 1,1,2,2-tetrafluorocyclopropane (TFC) to 1,1-difluoroethylene and CF₂ was studied in the temperature range of 507.0-577.0 K and with a total pressure of 200 to 300 torr of a 1:100 mixture of reactant and C₂H₄. Also at 557.0 K experiments were made at different total pressures, in the range 2–20 torr with neat TFC and between 20–300 torr with the C₂H₄/TFC mixture, confirming that the reaction is in the high pressure limit. The reaction is first-order and the rate constants fit the following Arrhenius relationship: From this value of the activation energy, the data for the decomposition of chemically activated TFC were revised. The new results yield a minimum energy of the activated molecule of 98 ± 4 kcal/mol and ΔH(TFC) = ?155.4 ± 7 kcal/mol, while an analysis of the kinetic data yields ΔH(TFC) = ?159 ± 9 kcal/mol.