Das unterschiedliche massenspektrometrische Fragmentierungsverhalten von Lysinmethylester und dessen N,N′‐Diacetylderivat. 27. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

Abstract

The Different Behaviour of Lysine Methyl Ester and its N,N′‐Diacetyl Derivative under Electron ImpactThe base peak in the spectrum of lysine methyl ester is due to the fragment ion C5H10N (m/e 84), for which the cyclic structure g (Scheme 1) is deduced. During its formation from the [M‐COOCH3]‐ion an equilibration of both nitrogen atoms takes place (ion c, Scheme 1). The cyclic nature of ion m/e 84 is in agreement with the intensity of the corresponding ions in the spectra of homologues of lysine methyl ester (Fig. 1). Although in comparison with lysine methyl ester (1) N,N′‐diacetyl‐lysine methyl ester (7) shows the same general fragmentation pathway with formation of the ions [M‐COOCH3] and [M‐COOCH3‐H2NCOCH3] (m/e 126), the exact fragmentation mechanism proves to the different. Two mechanisms are discussed for the formation of the ion m/e 126 from 7 (Schemes 2 and 3). The results are based on the spectra of labelled derivatives.