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Proton magnetic resonance studies of tautomerism in substituted pyrimidines

✍ Scribed by Jay A. Glasel

Publisher
John Wiley and Sons
Year
1969
Tongue
English
Weight
430 KB
Volume
1
Category
Article
ISSN
0749-1581

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✦ Synopsis

Studies of line width and chemical shift us. temperature for amide and hydroxyl proton magnetic resonance signals from: barbituric acid, dialuric acid, parabanic acid, alloxan and alloxan monohydrate dissolved in anhydrous dimethyl sulfoxide-d6 are reported. The behavior of the amide signals shows that, between 20 and 6 5 T , none of the compounds listed exhibits lactim-lactam tautomerism. The amide proton resonance in uracil has also been investigated. The signal is a closely spaced, equal intensity, doublet due to the non-equivalence of H(l) and H(3). Again, no evidence of tautomerism is observed. Activation energies for the hydroxyl resonances in dialuric acid and alloxan monohydrate indicate hydrogen bonding between solute and solvent. The results of simple LCAO-MO calculations are in accord with the experimental conclusions concerning tautomeric equilibria.

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