Premium
The decompositions of metastable [C 4 H 8 O] + ˙ ions and the [C 4 H 8 O] + ˙ potential surface
Author(s) -
McAdoo David J.,
Hudson Charles E.
Publication year - 1983
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210181104
Subject(s) - ion , metastability , chemistry , spectral line , decomposition , oxygen , crystallography , carbon fibers , analytical chemistry (journal) , atomic physics , physics , materials science , organic chemistry , astronomy , composite number , composite material , chromatography
Collisionally activated decomposition (CA) spectra of [C 4 H 8 O] + ˙ ions and the products of their metastable decompositions are used to refine a previously presented picture of the reactions of [C 4 H 8 O] + ˙ ions. Metastable [C 4 H 8 O] + ˙ isomers predominantly rearrange to the 2‐butanone ion and decompose by loss of methyl and ethyl, although up to 38% of the methyl losses take place by other pathways to form \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{CH}}_{\rm{2}} = {\rm{CHCH = }}\mathop {\rm{O}}\limits^{\rm{ + }} {\rm{H}}{\rm{.}} $\end{document} . The CA spectra of many of the [C 4 H 8 O] + ˙ ions with the oxygen on the first carbon are very similar, consistent with those ions isomerizing largely to common structures before or after collision. However, several of these ions have unique CA spectra, so they must remain structurally distinct from the majority of the [C 4 H 8 O] + ˙ ions below energies required for decomposition. The CA spectra of ions with the oxygen on the second carbon are distinct from those of ions with the oxygen on the first carbon, so there is limited interconversion of the non‐decomposing forms of the two types of ions. A potential energy diagram for the reactions of metastable [C 4 H 8 O] + ˙ ions is constructed from appearance energy measurements. As would be expected, the relative importances of most of the [C 4 H 8 O] + ˙ isomerizations seem to be inversely related to the activation energies for those processes. Some parallels between the isomerizations of [C 4 H 8 O] + ˙ ions and those of related ions are pointed out.