Abstract: | A new type of amine fragmentation under electron impact is elucidated for proline, sarcosine and aspartic acid derivatives and aminomethylphosphines of the general formula R2NCH2X. Ordinary α-cleavage affording the \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}_2 \mathop {\rm N}\limits^{\rm + } {\rm = CH}_{\rm 2} $\end{document} ion is suppressed by elimination of a neutral HX particle and M - HX]+ ion formation, or M-HX neutral particle ejection and generation of an HX]+ ion from M]+˙. Such fragmentation is ensured by the presence of an α-heteroatom (N, O, P, S) in one substituent (X) and a CO2R type delocalizing group in the α-position of the other substituent (R2N). |