Chemistry of recoil tritium atoms. Part 5.—Extension of the Estrup–Wolfgang theory of hot atom reactions to mixtures of reactive components

Abstract

The Estrup–Wolfgang theory for the analysis of data from hot-atom experiments is extended to include the case of two reactive components. Energy shielding (K) integrals are found which describe the way in which the reactions of one component are affected by the reactions of high energy atoms with the other component. The theory is applied to the system in which recoil tritium atoms reacts with mixtures (and helium moderated mixtures) of ethylene with propene trans-but-2-ene and isobutene and also ethane with trans-but-2-ene. It is shown that the mean energy of tritium atoms that cause labelling and products derived from addition to the double bond increases in the sequence isobutene, ethylene, propene and trans-but-2-ene. With the exception of isobutene this order is explained by postulating that lower energy recoil tritium atoms can react at an sp² site than at an sp³ site. The proposed extension of the theory would not seem to be suitable for the analysis of the data from the ethane + but-2-ene system. But helium moderated experiments show that both ethane and trans-but-2-ene “shield” each other indicating that the labelling reaction for both is initiated by recoil atoms in a comparable energy range.