(E)-4-[(4-Diethyl­amino-2-hy­droxy­benzyl­idene)amino]­benzoic acid

In the title compound, C(18)H(20)N(2)O(3), a potential bidentate N,O-donor Schiff base ligand, the benzene rings are inclined at an angle of 12.25 (19)°. The mol­ecule has an E conformation about the C=N bond. One of the ethyl groups is disordered over two positions, with a refined site-occupancy ratio of 0.55 (1):0.45 (1). An intra­molecular O—H⋯N hydrogen bond makes an S(6) ring motif. In the crystal, pairs of O—H⋯O hydrogen bonds link mol­ecules, forming inversion dimers with R (2) (2)(8) ring motifs.