Article ID Journal Published Year Pages File Type
1401682 Journal of Molecular Structure 2015 8 Pages PDF
Abstract
Electronic effects on keto-enol tautomerism of 1-(p-substituted aryl)-1,3-diketone malonates 1-10 were determined and established by NMR-Hammett linear free energy relationships. In addition, tautomeric equilibrium constants were determined for the title compounds by 1H NMR in DMSO-d6, showing an increasing to diketo tautomer with the increasing in the temperature. In this context, the enol form becomes less stable with increasing temperature suggesting that the intramolecular hydrogen bonding of the cis enol-keto form are increasingly broken at higher temperatures. In general, the enolic form (rather than the keto) is the most stable conformation due to its six member cyclic structure fulfilled by an internal O-H … O hydrogen bond.
Related Topics
Physical Sciences and Engineering Chemistry Organic Chemistry
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