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Unexpected course of olefin loss from some alkylcyclopentanone ions. Gaseous ion structure by ion cyclotron resonance spectrometry, mass‐analyzed ion kinetic energy spectrometry and collision‐induced dissociation
Author(s) -
Hass J. Ronald,
Cooks R. Graham,
Elder James F.,
Bursey Maurice M.,
Kingston David G. I.
Publication year - 1976
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.1210110704
Subject(s) - chemistry , mass spectrometry , ion , fourier transform ion cyclotron resonance , ion cyclotron resonance , collision induced dissociation , dissociation (chemistry) , polyatomic ion , molecule , ion source , analytical chemistry (journal) , tandem mass spectrometry , organic chemistry , chromatography , cyclotron
Ion cyclotron resonance results show that the ions formed by single and by double McLafferty rearrangement in 2‐ethyl‐5‐propylcyclopentanone have neither keto nor enol structures. Collision‐induced dissociations confirm that these ions are structurally distinct from the keto ions formed directly by electron impact upon the corresponding neutral molecules. It is suggested that the major reaction path for olefin loss from 2‐ethyl‐5‐propylcyclopentanone and from 2‐ethylcyclopentanone involves ring opening followed by hydrogen transfer to carbon in the alkene elimination step. Only in metastable ions is there evidence for the occurrence of the normal McLafferty rearrangement. The techniques mentioned in the title, together with conventional low and high resolution mass spectrometry, have been used to characterize the sometimes complex mixtures of cyclic and acyclic ions formed from cyclopentanone and some of its alkyl derivatives. Use of a number of different techniques of ion structure characterization allowed corroboration of particular results by quite distinct methods and it also allowed the effects of ion internal energy and lifetime upon structure to be partly elucidated.