STUDY OF RADICAL MEROSTABILIZATION BY ELECTROSPRAY FTICR/MS

摘要

The threshold fragmentation energies (E(0)) of three different 4-(1'-substituted-2'-phenethyl)-1-methylpyridinium salts containing a neutral, an electron-donor, or an electron-acceptor group as alpha-substituent, respectively, were measured by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR/MS) collisionally activated dissociation (CAD). N-Methyl-4-(1-ethoxy-2-phenylethyl)pyridinium iodide (10), containing both electron-donor and electron-acceptor substituent groups, has a significantly lower E(0) than the analogs containing a benzyl (6) or benzoyl (7) substituent. This was ascribed to merostabilization of the corresponding radical 19, and this conclusion was further supported by theoretical calculations.