The gas phase structure of some protonated and ethylated aromatic amines

The fundamental processes of protonation and ethylation, occurring in a methane chemical ionization source, have been investigated for a variety of aromatic amines. The positions of protonation and ethylation on the substrate amines were determined by generating isomeric ions either by protonation of neutral ethyl substituted amines or by ethylation of the amines themselves. The product ions were investigated for structural differences via collision induced dissociation and subsequent analysis via mass analysed ion kinetic energy spectrometry. Similarities and differences between mass analysed ion kinetic energy/collision induced dissociation spectra of these isomeric ions were used to determine protonation and ethylation sites for imidazole, benzimidazole, indazole, pyrrole, pyridine and aniline.