Analysis of Tautomerism in β-Ketobuanamides by Nuclear Magnetic Resonance: Substituent, Temperature and Solvent Effects
DOI:
https://doi.org/10.6000/1929-5030.2012.01.01.2Keywords:
keto-enol equilibrium, nuclear magnetic resonance spectroscopy, beta-ketoamidesAbstract
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.
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Published
2012-10-15
How to Cite
Laurella, S., Sierra, M. G., Furlong, J., & Allegretti, P. (2012). Analysis of Tautomerism in β-Ketobuanamides by Nuclear Magnetic Resonance: Substituent, Temperature and Solvent Effects. Journal of Applied Solution Chemistry and Modeling, 1(1), 6–12. https://doi.org/10.6000/1929-5030.2012.01.01.2
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