Dissociative Benzyl Cation Transfer versus Proton Transfer: Loss of Benzene from Protonated N-Benzylaniline

Abstract

In collisional activation of protonated N-benzylaniline, the benzene loss from the benzyl moiety is actually not the result of dissociative proton transfer (PT). In fact, benzyl cation transfer (BCT) from the nitrogen to the anilinic ring (ortho or para position) is the key step for benzene loss. Such dissociation occurs only after the benzyl group migrating from the site with the highest benzylation nucleophilicity (nitrogen) to a different one (aromatic ring carbon), which is described as dissociative benzyl cation transfer.

Intramolecular Halogen Transfer via Halonium Ion Intermediates in the Gas Phase

“…The fragmentation reactions of organic compounds in multi-stage mass spectrometry are directly related to their structures, but the interpretation of mass spectra is not always straightforward because of many rearrangements that take place during fragmentation. In recent years, considerable research in ESI-MS has focused on studying the skeletal rearrangements of organic compounds, including alkyl transfer [24,25], benzyl cation transfer [26][27][28][29][30], benzoyl cation transfer [31], phosphate group migration [32], intramolecular electrophilic substitution [33,34], tosyl cation transfer [35], and ion/neutral complexmediated fragmentations [36][37][38][39].…”

Analysis of sesquiterpene pyridine alkaloids using ESI–MS/MS: The product ion at m / z 310 formed by an ion–dipole intermediate

“…An interesting product ion at m/z 310 was detected and possible forming process was shown in Scheme 1. The processes involve an intermediate formed by the McLafferty-type rearrangement and an ion-dipole complex [18][19][20][21][22][23][24]. Close distance might contribute to the addition reaction between oxo(phenyl)methylium formed by the loss of benzoic acid side chain linked to C1 and pyridine moiety.…”

“…Structural information provided by ESI-MS is obtained by characteristic fragmentation reactions. Interestingly, a product ion can be rationalized by considering the formation of intermediate ion-dipole (ion-neutral) complexes [18][19][20][21][22][23][24][25].…”

Decarboxylative Coupling Reaction in ESI(−)-MS/MS of 4-Nitrobenzyl 4-Hydroxybenzoates: Triplet Ion–Neutral Complex-Mediated 4-Nitrobenzyl Transfer

“…The sum of the free energy of the separated 2-methoxy-4-carboxylate-phenoxyl and nitrobenzyl radicals is higher than that of 1-INC-t by 24.7 kJ/mol; this indicates that 1-INC-t is relatively stable. INC is an important intermediate in gasphase chemistry, and various chemical reactions can occur between the two species or in the ionic fragment alone prior to its final separation [6,8,17,[19][20][21][22][23][24]. In addition to direct separation to Figure 5S).…”

“…However, the gasphase C-C coupling reactions such as methyl and benzyl transfers that occur in tandem mass spectrometry (MS/MS) often cause problems in MS-based structural elucidations, and have therefore attracted much attention [4][5][6][7]. Benzyl cations are relatively stable in the gas phase and are easily formed during MS by fragmentation of benzylated species [8,9].…”