2-Chloro-3-(4-methylanilino)naphthalene-1,4-dione

In the title compound, C17H12ClNO2, the naphthoquinone system is essentially planar [maximum deviation = 0.078 (2) Å] and makes a dihedral angle of 52.38 (7)° with the benzene ring. The crystal structure features N—H⋯O interactions.

In the title compound, C 17 H 12 ClNO 2 , the naphthoquinone system is essentially planar [maximum deviation = 0.078 (2) Å ] and makes a dihedral angle of 52.38 (7) with the benzene ring. The crystal structure features N-HÁ Á ÁO interactions.

Li-Jiu Gao and Yun Liu Comment
The substituted naphthoquinone have a diversity of biological activity and are playing an increasingly important role in developing new pharmaceuticals [Batton et al., 2000;Monks et al., 1992]. In our ongoing research work on the syntheses of amino-substituted naphthoquinones, we have prepared the title compound, (I), as one of the products. As part of this study, we have undertaken an X-ray crystallographic analysis of (I) in order to confirm its structure.
In the title compound, the bond lengths and angles of the title molecule (  Table 1). The molecular packing is stabilized by intermolecular N-H···O hydrogen bonds (Table 2).

Experimental
To a stirred solution of naphthoquinone (1.0 eq) in 10 ml of acetonitrile, potassium carbonate (3.0 eq) was added. The mixture was stirred at room temperature for 5 min, followed by the addition of aniline (1.0 eq) and silver nitrate (0.1 mmol). The reaction mixture was refluxed for 10 h until complete consumption of starting material was observed on TLC. The reaction mixture was purified over silica gel (EtOAc/hexane)to afford the product in 96% yield.

Refinement
The H atoms were geometrically placed and were treated as riding, with C-H = 0.93 Å.

Computing details
Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software (Enraf-Nonius, 1989    Packing diagram.  (7) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger. Flack parameter does not have any meaning here. Obviously anomalous contribution from Cl was not good enough to resolve the chirality.