In the title mol-ecule, C(17)H(12)N(2)O(3), the naphthalene ring system and the pyridin-3-yl rings are nearly coplanar with a dihedral angle between them of 2.28 (8)°. In the crystal, the hy-droxy and amide N atoms participate in hydrogen bonds, which connect the mol-ecules into a two-dimensional network parallel to (101).

The title compound, C(7)H(3)Cl(2)NO(4), was prepared by the reaction of 2,4-dichloro-6-nitro-toluene with 20% HNO(3) solution at 430 K. The carboxyl and nitro groups are twisted by 82.82 (12) and 11.9 (2)°, respectively, with respect to the benzene ring. The crystal structure is stabilized by O-H⋯O hydrogen bonding between carboxyl groups and weak C-H⋯O hydrogen bonding between the nitro group ...

In the title compound, C(9)H(7)NO(6), the dihedral angles between the benzene ring and its three substituents are 29.99 (8)° for the nitro, 67.09 (8)° for the carb-oxy and 32.48 (10)° for the meth-oxy-carbonyl group. In the crystal, one classical O-H⋯O and two nonclassical C-H⋯O contacts link adjacent mol-ecules, forming a three-dimensional structure.

The title compound, C(7)H(4)ClFO(2), is a twofold halogenated derivative of benzoic acid. The C-C-C angles within the aromatic moiety cover a range 116.11 (14)-123.96 (15)°, with the maximum and the minimum value next to each other. In the crystal, O-H⋯O hydrogen bonds form carb-oxy-lic acid dimers, which are further connected by C-H⋯F contacts into undulating sheets perpendicular to the a axis.