Citrazinic acid

Citrazinic acid is a heterocyclic compound consisting of a dihydropyridine ring derived from citric acid. The yellow solid exists as multiple tautomers; as seen also for the simpler 2-pyridone.

Citrazinic acid is very sparingly soluble in water, acid and methanol but is soluble in basic solutions (e.g. ammonia water). For NMR purposes it is also sparingly soluble in d6-DMSO (2H, 6.20 ppm).