The kinetics and the mechanism of the thermal decomposition of bis-pentafluorosulfurtrioxide (SF5OOOSF5)

The thermal decomposition of SF₅O₃SF₅ has been investigated between 5 and 25°C. In the presence of sufficient high pressures of O₂ the only products formed are SF₅O₂SF₅ and O₂: The reaction is homogeneous. Its rate is strictly first order with respect to the trioxide pressure and independent of the total pressure of the reaction products and of oxygen above a certain limiting pressure: The experimental results can be explained with the following mechanism: In the presence of O₂ > 100 Torr the concentration of SF₅ is insignificantly small. Therefore reactions (5) and (6) do not have to be considered any more, and steps (2) and (2′) will be of no importance. From reactions (1)–(4) it follows: The numerical value of the factor 1 + (k′₁²/2k₃k₄)^1/2] is small. It can be estimated that E₃ ? 2 ± 1 kcal; therefore, E – E₁ ≤ 1 kcal, and D = (26 – 1) ± 1.0 kcal.