info:eu-repo/semantics/article
Analysis of Tautomerism in beta-Ketobutanamides by Nuclear Magnetic Resonance: Substituent, Temperature and Solvent Effects
Fecha
2012-08Registro en:
Laurella, Sergio Luis; Analysis of Tautomerism in beta-Ketobutanamides by Nuclear Magnetic Resonance: Substituent, Temperature and Solvent Effects; Lifescience Global; Journal of Applied Solution Chemistry and Modeling; 1; 1; 8-2012; 1-7
1929-5030
CONICET Digital
CONICET
Autor
Laurella, Sergio Luis
Resumen
β-ketoamides are versatile intermediates for the synthesis of several heterocycles and they are also relevant compounds in biological systems, with their tautomeric equilibria being a crucial aspect to be studied in order to understand their chemical and biological behaviour. Tautomeric equilibria of a series of β-ketobutanamides were analyzed by means of 1HNMR, determining that ketoamide and Z-enolamide are the main tautomeric species in solution, both presenting internal hydrogen bonds. Keto-enol equilibrium predominates over other possible tautomerisms (e.g. amide-imidol). The enol tautomer appears to be favoured by electron withdrawing substituents and non-protic solvents. Thermodynamic parameters ΔH and ΔS were determined in CDCl3 and DMSO-d6, showing that the keto-enol equilibria are exothermic and require a molecule order increase.