Kinetics and mechanism of the gas‐phase thermal reaction between bis(fluoroxy) difluoromethane CF 2 (OF) 2 and carbon monoxide

The kinetics of the gas‐phase thermal reaction between CF 2 (OF) 2 and CO has been studied in a static system at temperatures ranging between 110 and 140°C. The only reaction products were CF 2 O and CO 2 , giving the following stoichiometry:\documentclass{article}\pagestyle{empty}\begin{document}$${\rm CF}_{\rm 2} {\rm (OF)}_{\rm 2} {\rm + 2CO = 2CF}_{\rm 2} {\rm O + CO}_{\rm 2} {\rm}\Delta n{\rm = 0}$$\end{document}The reaction is homogeneous. The rate is strictly second order in CF 2 (OF) 2 and CO, and is not affected by the total pressure or by the presence of reaction products. Oxygen promotes a sensitized oxidation of CO and inhibits the formation of CF 2 O. The experimental results in the absence of oxygen can be explained by a chain mechanism similar to that proposed for the reaction between F 2 O and CO with an overall rate constant of\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = 1.45 \times 10^9 {\rm exp}(- 20,900/RT)L/mol \cdot s$$\end{document}From the experimental data obtained on the oxygen‐inhibited reaction, the rate constant for the primary process can be calculated:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {({\rm I})} \quad {{\rm CF}_{\rm 2} ({\rm OF)}_{\rm 2} + {\rm CO} \to {\rm CF}_{\rm 2} (\mathop {\rm O}\limits^{\rm .}){\rm OF} + {\rm F}\mathop {\rm C}\limits^{\rm .} {\rm O}} \quad\quad {k_1 = 1.45 \times 10^9 {\rm exp}(- 20,900/RT)L/mol \cdot s} \\\end{array}$$\end{document}The chain length v = 2.5 is independent of the temperature. Taking for collision diameters σ   CF   2  (OF)   2= 6 Å and σ CO = 3.74 Å, a value α = 5.3 × 10 −3 for the steric factor is obtained.