Potentially tautomeric pyridines. Part IX. The effect of chlorine substituents on pyridone–hydroxypyridine tautomerism

Abstract

Chlorine atoms α to the nitrogen displace the tautomeric equilibrium of pyridones significantly in favour of the hydroxypyridine form, whereas chlorine atoms in other positions have much less effect. α-Monochloropyridones are shown to exist to an increasing extent in the hydroxypyridine form as the dielectric constant of the medium decreases.