Relative rate constants for the reaction of ground-state oxygen atoms with partly fluorinated propylenes and butenes

Abstract

The reactivity of ground-state oxygen atoms generated by mercury-sensitized decomposition of N₂O has been investigated with olefins containing fluorine. Relative rate constants for the reaction with seven propylenes and butenes containing one to three fluorine atoms were measured by the competitive method at 23 ± 1 °C. The results are summarized below relative to a common reference olefin (ethylene): CH₃CFCH₂, 2.6₆ : CH₂FCHCH₂, 1.12 : CH₃CHCF₂, 2.4 : CF₃CHCH₂, 0.057 : CH₂FCH₂CHCH₂, 3.30 : CF₃(CH₃)CCH₂, 0.45 : CH₃CH₂CFCF₂, 5.0. Replacement of hydrogen by fluorine at any position in the molecule decreased the reactivity of the olefin to O³P atoms. The variations in the relative rate constants are discussed in terms of the electron-withdrawing inductive effect and electron-donating mesomeric effect of the fluorine atom.