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

Abstract

The presence of [ M + H] + ions was observed in the electron impact mass spectra of the series of dimers of aliphatic tertiary p, y-and Gnitrosonitriles. Neither M+' nor [M + HI + ions are observed in the spectra of a-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 p and Gnitrosonitriles. 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 + HI +' ion in the liquid secondary ion mass spectrum of a y-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 (CH,),C(NO)R.nitriles 2-4 and 8-11 were obtained from the corre-

Application of self-ionization for enhancing stereochemical and positional effects from arylglycosides under electron ionization conditions in an ion trap mass spectrometer

“…However, such processes are some-what weakly efficient into an EI source of an ion beam mass spectrometer. Nevertheless, the use of a temporal mass spectrometer, such as an ion trap [17][18][19], causes the self-ionization analytical technique to be particularly effective. This is because the reagent ions can be selectively stored for a relatively large reaction time that can be varied and optimized so as to enhance the yield of ion-molecule reactions.…”