Rate parameters for reaction of oxygen atoms with C2F4, CF2CFCl and CF2CCl2

Abstract

Ground-state CF₂ was monitored by kinetic spectroscopy after long wavelength flash photolysis of C₂F₄+ NO₂+ N₂ mixtures and was ascribed as a product of the overall reaction O(2³P)+ C₂F₄→ CF₂O + CF₂. (1) From the decrease in the CF₂ yield in competitive systems, rate constants relative to k₁ were determined for CF₂CFCl and CF₂CCl₂. The reactivities of the chlorofluoroethylenes show a similar trend with ionization potential to that established for hydrocarbon olefins. From preliminary measurements of the overall decomposition of C₂F₄ flashed in O₂ at 25°C, it is proposed that singlet CF₂ reacts with O₂ about 0.2 times as rapidly as with C₂F₄. Although there was no direct evidence for triplet CF₂ molecules formed in (1), the results are consistent with an earlier analysis of continuous photolysis experiments, if CF^* ₂ is rapidly relaxed in collisions with NO₂ or NO.