Amido (A)/imido (B) tautomerism has been investigated by UV/Vis and NMR spectroscopic methods for a number of 2-acetamidothiazoles and 2-acetamidobenzothiazoles, without the use of the physical properties of "fixed parents". The addition of polar substances to solutions of selected compounds in apolar solvents (carbon tetrachloride, dichloromethane) strongly affects the [B]/[A] ratios. Data show that the shift of the tautomeric equilibrium A/B towards the B form has two main causes: (i) increase of the polarity of the medium, and (ii) a base effect on the stabilization of the B form. The experimental ΔH and ΔS values indicate (in agreement with 1H NMR spectroscopic data) that the self-assembly of 2-acetamido derivatives is a very important factor in determining the position of the tautomeric equilibrium.
Forlani, L., Mezzina, E., Boga, C., Forconi, M. (2001). Tautomerism and dimerization of acetamidothiazole derivatives - UV/Vis and NMR spectroscopic investigation. EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, 2001(14), 2779-2785 [10.1002/1099-0690(200107)2001:14<2779::aid-ejoc2779>3.0.co;2-n].
Tautomerism and dimerization of acetamidothiazole derivatives - UV/Vis and NMR spectroscopic investigation
Mezzina E.;Boga C.;
2001
Abstract
Amido (A)/imido (B) tautomerism has been investigated by UV/Vis and NMR spectroscopic methods for a number of 2-acetamidothiazoles and 2-acetamidobenzothiazoles, without the use of the physical properties of "fixed parents". The addition of polar substances to solutions of selected compounds in apolar solvents (carbon tetrachloride, dichloromethane) strongly affects the [B]/[A] ratios. Data show that the shift of the tautomeric equilibrium A/B towards the B form has two main causes: (i) increase of the polarity of the medium, and (ii) a base effect on the stabilization of the B form. The experimental ΔH and ΔS values indicate (in agreement with 1H NMR spectroscopic data) that the self-assembly of 2-acetamido derivatives is a very important factor in determining the position of the tautomeric equilibrium.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
