1-Ethyl-4-hydroxy-2-oxo-1,2-di­hydro­quinoline-3-carboxyl­ic acid

An X-ray diffraction study of the title compound, C₁₂H₁₁NO₄, has shown that this compound exists in the crystal as the 2-oxo-4-hydroxy tautomer. The formation of two O—H⋯O=C-type intramolecular hydrogen bonds leads to the elongation of both exocyclic and carboxyl­ic C=O double bonds involved in the hydrogen bonding, causes shortening of the exocyclic C—O single bond, and also affects the C—C bond lengths in the di­hydro­pyridine ring.