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The mass spectrometric [M C 2 H 4 O] + process in cyclic ketones. I—the nature of the C 2 H 4 O losss in bicyclo[3.3.1]nonan‐2‐one and 3‐one
Author(s) -
Cable J.,
MacLeod J. K.
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.1210111009
Subject(s) - chemistry , bicyclic molecule , deuterium , fragmentation (computing) , molecule , labelling , mass spectrum , stereochemistry , hydrogen , ion , crystallography , medicinal chemistry , organic chemistry , physics , biochemistry , quantum mechanics , computer science , operating system
Although the loss of a C 2 H 4 O molecule from the molecular ions of the isomeric bicyclo[3.3.1]nonan‐2‐ and 3‐ones gives rise to the base peak at m/e 94 in both spectra, deuterium labelling results show that the processes leading to this ion are markedly different in the two cases. While the 2‐one follows essentially (>80%) the same [M C 2 H 4 O]+ fragmentation pathway described for other 2‐alkylcyclohexanones, the 3‐one exhibits a more complex decomposition pathway in which one α‐hydrogen is transferred away from the departing C 2 unit and three hydrogen atoms are subsequently rearranged to the eliminated C 2 H 4 O molecule. Similar competing fragmentation schemes have been invoked to explain deuterium labelling results in cycloheptanone, 2‐methylcycloheptanone and cyclooctanone.