1-(3-Chlorophenyl)-5-(2,4-dihydroxybenzoyl)pyridin-2(1H)-one

The chlorophenyl group of the title compound, C18H12ClNO4, is disordered over two orientations with occupancies of 0.331 (8) and 0.669 (8). An intramolecular hydrogen bond is formed between a hydroxy group and the acyclic carbonyl group. In the crystal, molecules are linked into chains along [110] by O—H⋯O and C—H⋯O hydrogen bonds, forming a ladder motif.


Experimental
A solution of 7-methoxy-chromen-4-one (0.015 mol) in methanol (150 ml) was added dropwise to a solution of piperidine (0.030 mol) and rufluxed for 3 h at 0°C to get a crude product. This was added dropwise to a solution of dichloromethane (150 ml) and I 2 for an overnight reaction to give 3-iodo-7-methoxy-chromen-4-one with a 70% yield.

Refinement
All hydrogen atoms bonded with carbon atoms were placed in calculated positions using a riding model, with d(C-H) = 0.93 Å and U iso (H) = 1.2 U eq (C). The orientations of the hydrogen atoms in the hydroxyl groups were determined using difference Fourier maps. The disordered chlorophenyl group was divided into two parts (33%:67%). A FLAT group

Figure 1
Molecular structure with the numbering scheme adopted and ellipsoids drawn at the 30% probability level.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (