Experimental and Theoretical Studies on Tautomerism and Acid−Base Behavior of N-(2-Oxo-2H-chromen-3-yl)acetamide

• Published in: Journal of chemical and engineering data Vol. 55; no. 12; pp. 5634 - 5641
• Main Authors: Öğretir, Cemil, Duran, Murat, Aydemir, Sinem
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09.12.2010
• Subjects: Chemistry; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; Organic chemistry; Preparations and properties; Acid base balance; Lactone; Tautomerism; Experimental study; Coumarine derivatives
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/je100530r

The structures of all of the chemical species involved in the prototropic tautomerism and acid−base dissociation equilibria of N-(2-oxo-2H-chromen-3-yl)acetamide were determined both experimentally and theoretically. Using the calculated acidity constants, the prototropic equilibrium constants for keto−enol tautomerizm were determined. The enolate and the keto-amino forms were found to be predominant. The gauge including atomic orbital method for calculating 1H and 13C NMR nuclear magnetic shielding tensors at both the Hartree−Fock and density functional levels of theory was applied to N-(2-oxo-2H-chromen-3-yl)acetamide. The obtained theoretical data were compared to the experimental data. A satisfactory agreement between the experimental chemical shifts and the theoretical values of shielding constants were obtained. Acceptable correlations were presented between experimental and theoretical results.