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Mass spectrometry of condensed N ‐heterocycles: II—A novel ortho effect in the electron impact induced fragmentation of some C ‐(2‐nitrophenyl)‐azoles and ‐azoloazines
Author(s) -
Könnecke A.,
Lepom P.,
Dörre R.,
Lippmann E.,
Herzschuh R.,
Kralj B.,
Stanovnik B.,
Tišler M.
Publication year - 1980
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.1210150204
Subject(s) - isomerization , chemistry , moiety , fragmentation (computing) , ion , imine , mass spectrometry , photochemistry , electron transfer , electron ionization , nitro , medicinal chemistry , computational chemistry , stereochemistry , organic chemistry , ionization , catalysis , alkyl , chromatography , computer science , operating system
Heterocycles containing an integrated 2‐nitrobenzaldehyde imine moiety produce ions of m/z 134 with high abundance under electron impact. As shown by kinetic energy release measurements these ions have the same structure in all the cases studied, identical to m/z 134 formed from the reference compound 2‐nitrobenzoylpiperidide. The mechanism of formation of m/z 134 most probably involves isomerization of its precursor ion to give a spiro intermediate, from which m/z 134 arises either synchronously or after a second isomerization. Both alternatives formally represent an oxygen transfer from the nitro group to the imino carbon via a 5‐membered transition state.