Unusual behavior of some metastable ions: Non-occurrence of the lowest energy process.

Abstract The behavior of the three metastable ions : 2-butanone, 3-methyl-2-butanone and 2-penten-3-ol; is dominated by radical loss. These fragmentations don't correspond to the lowest energy pathways. It is demonstrated that the two former examples correspond to cases where the minimum rate constant value is greater than 10 6 s −1 . The role of an isomerization barrier upon competitive decompositions is illustrated by the tautomerism 2-penten-3-ol≷2-pentanone.