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The electron impact induced fragmentation of aromatic aldoximes—III. On the loss of HCNO, OH⋅ and substituents and the role of substituent effects in the decomposition of cyclohexadiene type intermediate ions
Author(s) -
Vijfhuizen Peter C.,
Terlouw Johan K.
Publication year - 1977
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.1210120413
Subject(s) - substituent , chemistry , fragmentation (computing) , ring (chemistry) , ion , hydrogen atom , hydrogen , photochemistry , medicinal chemistry , stereochemistry , organic chemistry , computer science , operating system , alkyl
The mechanisms for loss of HCNO, OH ˙ and the substituent X ˙ from aromatic aldosimes were elucidated with the aid of deuterium labelling, metastable ion characteristics and substituent effects. It is proposed that the loss of HCNO occurs through a cyclohexadiene type intermediate ion generated via a 6‐membered ring hydroxyl hydrogen transer to the ortho position of the phenyl ring. This is followd by a second step which involves the trnsfer of a hydrogen atom from the ortho position to C‐1. It is inferred from the corelation with the mesomeric effect (σ R + ) of substituents that this step is rate determining. Loss of OH ˙ and X ˙ proceed via the same cyclohexadiene type intermediate ion but, depending upon the substituent, other pathways are also followed.