14N and 13C NMR of tautomeric systems of hydroxy-pyridines

¹⁴N NMR is shown to be an efficient method of investigation of the tautomeric equilibria in hydroxy-and related substituted pyridines. Large relative ¹⁴N chemical shifts within tautomeric pairs estimated from N-Me and O-Me derivatives make possible quantitative determinations of the equilibria. Qualitative conclusions may be drawn from ¹⁴N line widths as well as from ¹³C and proton chemical shifts.