The electron impact induced fragmentation of aromatic aldoximes—II. Substituent effects on the loss of MCN

Loss of HCN from the molecular ion of benzaldoximes occurs via two distinct involving a 4-membered and a 5-membered intermediate, respectively. Both low energy high energy molecular ion decomposition were investigated by means of metastable peak shapes and the energetics of further decomposition of ions, respectively. Substituent effects previously held responsible for differences in the behaviour of m- and p-methoxybenzaldoximes are shown to be negligible; the differences are due to the differense in internal energy contents.