Reaktionen von Glutaminsäuredimethylester im Massenspektrometer. 21. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

✍ Scribed by Elsbeth Lerch; Manfred Hesse

• Publisher: John Wiley and Sons
• Year: 1974
• Tongue: German
• Weight: 912 KB
• Volume: 57
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19740570613

✦ Synopsis

Abstract

The mass spectral fragmentation of dimethyl glutamate (1) and its deuterated derivatives 1a, 1b and 1c has been investigated. By loss of a methoxycarbonyl group from the molecular ion an ion of m/e 116 is generated. The latter splits off methanol (m*), the resulting fragment of m/e 84 giving raise to the base peak of the spectrum. Only part of the hydrogen transferred to the leaving group originates from thc amino group, as was suggested earlier [2] [3]. Basing on experiments with deuterated compounds we propose an additional mechanism for the reaction, i.e. hydrogen transfer from C(3) to methoxyl. The fragment generated by both processes is most likely to be a pyrrolinonium ion. Thermal side reactions in the mass spectrometer (formation of pyroglutamic acid ester) followed by fragmentation may lead to the same ion. – The mechanisms discussed are supported by the mass spectral fragmentation of N‐acetyl‐glutamic acid diesters 3, 3a, 3b and 3d and of the N, N‐dimethyl derivatives 4 and 4a. – The fragmentation reactions investigated are similar to some of 1,3‐trimethylenediamine derivatives [7]. This means that there are parallels in the mass spectral fragmentation of difunctional compounds irrespective of the nature of the functional groups.