Kinetics and Mechanism of the Thermal Gas-Phase Reaction between NO2 and Trifluorobromoethene, CF2CFBr

Abstract

Abstract The reaction of NO2 with CF2CFBr has been studied at 322.6, 333.1 and 343.4 K, using a conventional static system. The initial pressure of CF2CFBr was varied between 26.9 and 75.5 torr and that of NO2 between 9.6 and 41.9 torr. Two experiments were made in presence of CF4 used as inert gas at the pressure of 238.8 and 334.6 torr, respectively. Five products were observed: CF2(NO2)C(O)F, CF2(NO2)CFBr(NO2), BrNO, Br2 and NO. The distribution of the products CF2(NO2)C(O)F and CF2(NO2)CFBr(NO2) was independent of the initial pressure of the reactants and the total pressure, but the relation CF2(NO2)C(O)F/CF2(NO2)CFBr(NO2) increased with the temperature. The reaction is homogeneous and independent of the total pressure. The following mechanism was postulated to explain the experimental results: 1 CF2CFBr + NO2 → CF2(NO2)C•FBr 2 CF2(NO2)C•FBr + NO2 + M → CF2(NO2)CFBrNO2 + M 3 CF2(NO2)C•FBr + NO2 → CF2(NO2)C(O)F + BrNO 4 2BrNO ↔ Br2 + 2NO k 1 = (1.51 ± 0.45) × 106 exp(−(10.88 ± 1) kcal mol−1/RT) dm3 mol−1 s−1.