ROLE OF DIFFERENT 5-SUBSTITUENTS ON THE MASS-SPECTROMETRIC BEHAVIOR OF URACIL

The influence of different 5-substituents on the mass spectrometric behaviour of uracil was systematically studied by means of mass-analysed ion kinetic energy spectrometry. By applying this technique to the molecular ions and the major primary product ions formed by loss of HNCO, the electron impact-induced fragmentation patterns of a series of substituted uracils could be elucidated. In addition to the common decomposition processes, distinctive fragmentation routes were identified for some compound , and a rationale for the observed behaviour is given based on the electronic properties of the substituents.