Determination of the most stable structures of selected hydroxypyrones and their cations and anions
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- 作者：Zborowski ; Krzysztof ; Grybos ; Ryszard ; Proniewicz ; Leonard M.
- 关键词：Hydroxypyrones ; Ketoenol tautomerism ; Equilibrium constants ; Quantum chemical calculations
- 刊名：Journal of Molecular Structure: THEOCHEM
- 出版年：2003
- 出版时间：November 3, 2003
- 年：2003
- 卷：639
- 期：1-3
- 页码：87-100
- 全文大小：318 K
文摘
Equilibrium geometries of selected hydroxypyrones were determined using quantum-mechanical calculations. Computations were performed for all possible structures of pyromeconic acid, maltol, ethylmaltol and kojic acid. Tautomerism of protonated and deprotonated (kojic acid) forms of the studied compounds were also taken into account. For all neutral tautomers of investigated compounds it was shown that the most stable was enolic form. Cationic species were created by protonation of the keto oxygen atom. In order to form stable kojic acid anion deprotonation of hydroxyl group on the pyran ring is preferred. Obtained results confirm that tautomeric equilibria in a gas phase were only slightly influenced by entropy.