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Mechanisms of water elimination and other degradations of 2‐hydroxy‐5‐ketobornane cations in the gas phase
Author(s) -
Fraefel A.,
Mändli M.,
Seibl J.
Publication year - 1981
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.1210160506
Subject(s) - chemistry , metastability , hydroxyl radical , hydrogen , ion , reagent , oxygen , borneol , gas phase , degradation (telecommunications) , ionization , mass spectrum , group (periodic table) , chemical ionization , photochemistry , computational chemistry , radical , organic chemistry , medicine , telecommunications , alternative medicine , traditional chinese medicine , pathology , computer science
The mechanisms of water elimination in 2‐hydroxy‐5‐ketobornanes have been investigated and compared with those in borneol and isoborneol in order to ascertain whether and how such processes are affected by incorporation of a remote second functional group of lower ionization energy. Analysis of metastable ion peak shapes and specific labelling with 2 H and 18 O are employed as methods for differentiating between individual reaction paths. In addition, those degradation reactions which give rise to the most prominent fragments and pattern differences in the mass spectra of the epimeric keto alcohols were scrutinized. The elimination of water is shown to exhibit entirely different features due to the presence of the carbonyl group. The other most important degradation reactions all proceed by hydrogen transfer from the hydroxyl group onto the charged product and concomitant loss of the hydroxyl oxygen in a neutral entity. The results are interpreted in terms of initial charge radical localization on the carbonyl group initiating the relevant chemical reactions. Peak shape analysis proves a very valuable, and at times the only useful way to distinguish individual reactions.