Chemistry of naphthazarin derivatives. 9. Direct observation of prototropic tautomerism of (poly) hydroxynaphthazarins by IR spectroscopy

VP Glazunov, AY Yakubovskaya, ND Pokhilo…

Index: Glazunov; Yakubovskaya; Pokhilo; Bochinskaya; Anufriev Russian Chemical Bulletin, 2003 , vol. 52, # 1 p. 198 - 207

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Abstract

Abstract A series of substituted (poly) hydroxylated naphthazarins (5, 8-dihydroxy-1, 4- naphthoquinones) were synthesized. In general,(poly) hydroxynaphthazarins exist in organic aprotic solvents as mixtures of tautomeric 1, 4-naphthoquinonoid forms (IR data). The ratio of tautomers was determined for the first time. The effects of the nature of substituents and the solvent polarity on the tautomeric equilibrium were qualitatively ...