Mass spectrometry of pyrimidine derivatives: Electron impact-induced decomposition of molecular ions of 4-amino-substituted and 4-amino-disubstituted 1,2-dihydro-1-methylpyrimidin-2-ones

Electron impact (EI) mass spectra of fourteen 4‐amino‐substiruted 1,2‐dihydro‐1‐methylpyrimidin‐2‐ones are reported. The EI‐induced decomposition of their molecular ions is significantly dependent on the chemical nature of the substituents. The routes of mass decomposition established suggest the presence of the tautomeric forms in the gas phase of some investigated compounds.