3-[(2-oxo-1-naphthylidene)methylamino]benzoic acid

The title compound, C18H13NO3, exists as a ketoamino tautomer implying a fa irly short N-H ... O intramolecular hydrogen bond between the 2-naphthaleno ne and amino moieties [N ... O 2.531 (3) Angstrom] which is enhanced by the pi-electron delocalization effect. The naphthaldimine and 3-carboxyphenyl fragments are inclined at an angle of 4.41 (7)degrees, so the molecule is a lmost planar. The molecules are connected by intermolecular O-H ... O hydro gen bonds between the carboxy and keto O atoms, forming infinite chains aro und the twofold screw axes parallel to b.