Origin of [M + H]+ ions in electron impact mass spectra of tertiary nitrosonitriles

✍ Scribed by Karol Grela; Leszek Konopski

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 532 KB
• Volume: 30
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.1190301009

✦ Synopsis

Abstract

The presence of [M + H]^+^ ions was observed in the electron impact mass spectra of the series of dimers of aliphatic tertiary β‐, γ‐ and δ‐nitrosonitriles. Neither M^+·^ nor [M + H]^+^ ions are observed in the spectra of α‐nitrosonitriles or after introduction of voluminous substituents into the molecule, so the geometric factor is very important. It was found that this effect was probably due to the rearrangement of the hydrogen atom in the fragmentation pattern of the dimer molecular ions 2M^+·^ of β‐ and δ‐nitrosonitriles. Aliphatic nitrosocompounds exist even in the gas phase in equilibrium with their dimers. The existence of dimers was confirmed by the presence of the [2M + H]^+·^ ion in the liquid secondary ion mass spectrum of a γ‐nitrosonitrile. Using deuterium labelling, as distinct to the nitrosoketones and esters, it was unexpectedly found that the origin of hydrogen in the [M + H]^+^ ions was the methyl groups in the position vicinal to the tertiary nitroso group (C__H__~3~)~2~C(NO)R.