Reaction of F atoms with dichloromethane by modulated molecular beam mass spectrometry

The reaction of atomic fluorine with dichloromethane has been studied by the diffusion cloud in a flow technique. Fluorine atoms were generated through F₂ dissociation in a high-frequency discharge. The reaction products were detected mass spectrometrically, applying the technique of focusing the paramagnetic component of the molecular beam in an inhomogeneous magnetic field to detect radical species. Cl atoms and CHCl₂ and CF₃ free radicals have been identified among the reaction products. The initial step was shown to be hydrogen atom abstraction. The room temperature rate constant of this reaction was found to be k₀ = (1.51 ± 0.28) X 10^?11 cm³/s. The rate constant of the secondary reaction of fluorine atoms with dichloromethyl radicals, which is suggested to produce mainly HCl, was evaluated as 3 X 10^?10 cm³/s.