Tautomeric equilibrium of amides and related compounds: theoretical and spectral evidences

The tautomeric equilibrium of several amides and related compounds is studi ed experimentally via mass spectrometry techniques. Experimental findings a re complemented with theoretical calculations in order to rationalise mass spectra results of some amides, thioamides, ureas and thioureas. Some furth er possible studies are pointed out in order to complement present findings . Both mass spectra and theoretical results indicate that tautomerism invol ves neutral species rather than the ionic analogues. Besides, thio-derivati ves have a relatively higher tendency to occur as imidols. (C) 2000 Elsevie r Science B.V. All rights reserved.