Mass spectral study of the occurrence of tautomeric forms of selected enaminones

- The mass spectra of some enaminones can provide valuable information regarding the ketoenamine-enolimine equilibria taking place in the gas phase.
- The predictive value of this methodology is supported by the influence of the nature and size of substituents on tautomeric equilibria and the rather good correlation existing between the abundance ratios of selected fragments.
- The present studies allow to predict that the ketoenamine structure are particularly stable for enaminones and while the enolenamine structure would predominate for thioenaminones.