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

AbstractThe 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 (σR+) 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.

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 Journal Articles