Mass Spectrometry of β-Ketoesters. Some Evidence of Their Tautomerism

Mass spectrometric evidence of tautomerism is reported for β-ketoesters. The analysis of the corresponding mass spectra has allowed specific the assignment of fragment ions to tautomers. The predictive value of this methodology is supported by the influence of a substitution pattern of these compounds on the equilibria. Experimental data are strongly supported by Austin Model 1 semi-empirical calculations, indicating that mass spectrometry could be resourced as a tool for the investigation of tautomerism of neutral species in the gas phase.