Unimolecular decomposition of [80Br]bromocyclopropane formed by reaction of recoil bromine atoms with cyclopropane or with bromocyclopropane
Abstract
The reactions of recoil bromine, from the 79Br(n,γ)80Br reaction, with cyclopropane and with bromocyclopropane have been investigated as a function of total pressure. The primary product, cyclo-C3H580Br, of the 80Br-for-H reaction in the former and of the 80Br-for-Br reaction in the latter, is highly excited and undergoes unimolecular decomposition to CH2CHCH280Br. The decomposition product from the former reaction still has enough energy to decompose further to the [80Br]bromomethyl radical which is isolated as CH280BrI in the presence of I2 scavenger. On the other hand most of the CH2CHCH280Br from the 80Br-for-Br reaction is stabilized either by collisional de-excitation or release of the 80Br atom.
From the potential energy diagrams of these decomposition pathways, the median excitation energies of the primary products are estimated to be greater than 4 eV for the 80Br-for-H reaction and 2–4 eV for the 80Br-for-Br reaction.