2-Allyloxy-5-nitrobenzoic acid

The molecule of the title compound, C10H9NO5, is approximately planar, with the mean planes of the nitro, carboxyl and allyloxy groups rotated by 8.1 (3), 7.9 (3) and 4.52 (18)°, respectively, from the plane of the benzene ring. Bond lengths in the aromatic ring are influenced by both electronic effects and strain induced by ortho-substitution. In the crystal structure, centrosymmetrically related molecules are paired into dimers through strong O—H...O hydrogen bonds.