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Isotope label scrambling in alkyl cations. A mechanistic proposal
Author(s) -
Tuinman A. A.,
Cook K. D.,
Macfarlane Ronald D.
Publication year - 1989
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290030904
Subject(s) - chemistry , scrambling , alkyl , protonation , isotope , dissociation (chemistry) , kinetic isotope effect , cyclopropane , ion , fragmentation (computing) , computational chemistry , deuterium , organic chemistry , atomic physics , nuclear physics , ring (chemistry) , philosophy , linguistics , physics , computer science , operating system
The observation of sharp limits to the chain lengths of alkyl cations derived by low energy collision‐induced dissociation of isotopically labelled trimethyltetradecylammonium cations, as well as the selectively limited scrambling of its isotope label, has prompted the proposal of a new mechanistic model for alkyl cation fragmentation. The model invokes protonated cyclopropane intermediates which may reopen to branched structures, or fragment (if suitably substituted) to form smaller alkyl cations and neutral olefins. The model accounts completely for the absence of daughter ions with fewer than three or more than six carbon atoms, while its semi‐quantitative application provides a reasonable match to the observed isotope scrambling.