Displacement reaction dynamics of fluorine atoms with allyl iodide molecules

Abstract Reactive scattering of F atoms with C 3 H 5 I molecules leading to I atom displacement has been studied at an initial translational energy E ≈ 40 kJ mol −1 using a supersonic beam of F atoms seeded in helium buffer gas. The centre-of-mass angular distribution of C 3 H 5 F scattering shows a broad peak in the forward direction with roughly constant relative intensity ≈ 0.4 in the backward hemisphere. The product translational energy distribution peaks at a low fraction ƒ′ pk ≈ 0.1 of the total available energy with a tail extending up to higher energy. Reaction occurs via a stripping mechanism whereby the F atom adds to the CC double bond forming a fluoroidopropyl radical which is unstable with respect to reaction products. The secondary fluoroiodopropyl radical formed by F atom addition to the carbon atom of the terminal CH 2 group fo C 3 H 5 I dissociates directly to form allyl fluoride reaction product, while the primary fluoroidopropyl radical formed by F atom addition to the carbon atom of the intermediate CH group dissociates via ring closure to form fluorocyclopropane reaction product.