5-Chloro-8-hydr-oxy-6-methyl-1,4-naphthoquinone.

The mol-ecule of the title compound, C(11)H(7)ClO(3), is planar, with a maximum deviation of 0.0383 (10) Šfrom the naphthoquinone plane. An intra-molecular O-H⋯O hydrogen bond generates an S(6) ring motif. The crystal packing is stabilized by inter-molecular C-H⋯O hydrogen bonds. Short intra-molecular Cl⋯O [2.8234 (8) Å] and O⋯O [2.5530 (11) Å], and inter-molecular Cl⋯Cl [3.2777 (3) Å] contacts further stabilize the crystal structure.

5-Hydr-oxy-8-nitro-1,4-naphthoquinone.

The title compound, C(10)H(5)NO(5), features an intra-molecular O-H⋯O hydrogen bond, forming a six-membered ring with an S(6) ring motif. The nitro group makes a dihedral angle of 71.66 (5)° with the plane of the benzene ring to which it is bound. The two rings are almost coplanar, with a dihedral angle of 4.44 (5)°. Short inter-molecular distances between the centroids of the six-membered rings [3.7188 (6)-3.8299 (6) Å] indicate the existence of π-π inter-actions. The inter-esting features of the crystal structure are the short inter-molecular O⋯O and O⋯N inter-actions. The crystal packing is stabilized by intra-molecular O-H⋯O and inter-molecular C-H⋯O (×3) hydrogen bonds, and C-H⋯π inter-actions.