COMPETING HYDROGEN REARRANGEMENTS IN THE MOLECULAR-IONS OF ALIPHATIC ESTERS - ION LIFETIME STUDY

The competition of the two most important hydrogen rearrangements in the molecular ion of aliphatic esters (formation of an alkene ion and the protonated acid) has been studied as a function of the ion lifetime for n-butyl acetate and propionate as well as n-propyl, n-butyl and n-pentyl butyrate. It is shown that, at lifetimes up to 10-11 s after ionization, the transitions-state geometry determines the relative ratio of the rates of formation of these two species. At longer lifetimes the decomposition can be explained in terms of the energetics, as shown by approximate calculation of the activation energies from thermodynamic data and by determination of appearance potentials. © 1979.