Mass Spectra of Substituted N‐Alkylpyrroles and Related Compounds

Abstract

Under El conditions, substituents on N‐alkylpyrroles affect fragmentation of the alkyl groups. The electron‐withdrawing character of the cyano group retarded formation of a N‐methylene cation, and a labile substituent, i.e., ‐CHO, ‐CH2COOMe, competed with an N‐alkyl group to be a initial fragmentation center, MNDO calculation of the heat of formation of possible fragment ions showed that protonated pyridine is the most stable among the isobaric ions.