Kinetics and mechanisms of the thermal gas-phase reactions of CF3OF and CF3OOCF3 with NO2

Article abstract of DOI:10.1524/zpch.1999.210.Part_1.083

The kinetics of the reactions of CF₃OF and CF₃OOCF₃ with NO₂ have been investigated using a conventional static system. The reaction between CF₃OF and NO₂ has been studied in a quartz reactor in the temperature range of 313.2-334.2 K, varying the initial pressure of CF₃OF between 19.4 and 165.2 Torr and that of NO₂ + N₂O₄ between 18.2 and 179.2 Torr. Some experiments were made in presence of 506.5-600.8 Torr of N₂. The total pressure had no influence on the reaction rate. COF₂ and FNO₂ were identified as reaction products. The expression obtained for the rate constant for the abstraction of fluorine atom from CF₃OF by NO₂ was: k₁ = (1.1±0.2) × 10⁹ exp(-16.4±1 kcal mol^-1/ RT) dm³ mol^-1 s^-1. The reaction of CF₃OOCF₃ with NO₂ has been studied in an aluminum reactor in the temperature range of 474.0-512.5 K, varying the initial pressure of CF₃OOCF₃ between 24.1 and 202.5 Torr and that of NO₂ between 24.7 and 202.7 Torr. Several experiments were made in presence of 399.8-490.5 Torr of N₂. The reaction rate was proportional to [CF₃OOCF₃]^1/2. The reaction approached the first order with respect to NO₂ at low pressure of NO₂. Increasing the pressure of NO₂, the ratio of the reaction rates increased more rapidly than the ratio of the corresponding concentrations of NO₂. Three products were formed: COF₂, FNO and O₂. The expression obtained for the rate constant for the abstraction of the fluorine atom from the radical CF₃O by NO₂ was: k₈ = (1.72±0.4) × 10⁹ exp(-10.8±1 kcal mol^-1/RT) dm³ mol^-1 s^-1. The mechanisms for both reactions were postulated. by Oldenbourg Wissenschaftsverlag, Muenchen.