4-[(E)-(5-Chloro-2-hydroxybenzylidene)amino]benzenesulfonamide

In the molecule of title compound, C13H11ClN2O3S, the aromatic rings are oriented at a dihedral angle of 12.27 (3)°. An intramolecular O—H⋯N hydrogen bond results in the formation of a planar (mean deviation 0.0083 Å) six-membered ring, which is nearly coplanar with the adjacent ring at a dihedral angle of 2.36 (13)°. In the sulfonamide group, the S atom is 0.457 (3) Å from the plane through the O and N atoms. In the crystal structure, intermolecular N—H⋯O hydrogen bonds link the molecules.


4-[(E)-(5-Chloro-2-hydroxybenzylidene)amino]benzenesulfonamide
Z. H. Chohan, H. A. Shad and M. N. Tahir Comment Sulfonamides have gained much attention due to their extensive use in medicine. Many novel sulfonamide derived compounds have been synthesized and reported (Chohan, 2008;Chohan & Supuran, 2008;Nishimori et al., 2005) that are expected to attack the selective targets. This approach is supportive in controlling undesirable effects and producing distinctive pharmacological and clinical responses. In continuation to synthesize Schiff base ligands of 5chlorosalicylaldehyde with different sulfonamides (Chohan et al., 2008a(Chohan et al., , 2008bShad et al., 2008), we have synthesized the title compound having the sulfanilamide, which is also a member of sulfonamides, and reported herein its crystal structure.
The crystal structures of the individual moieties of δ-sulfanilamide have also been reported (Gelbrich et al., 2008) .
In the molecule of title compound (Fig 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges.
In the crystal structure, intermolecular N-H···O hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Experimental
For the preparation of the title compound, sulfanilamide (344.4 mg, 2 mmol) in ethanol (20 ml) was mixed with 5-chlorosalicylaldehyde (313.1 mg, 2 mmol) in ethanol (10 ml). The resultant mixture was refluxed for 3 h by monitoring through TLC.
During refluxing the solution turned from colorless to bright orange. After completion of reaction, it was cooled to room temperature, filtered and volume reduced to about one-third using rotary evaporator. It was then allowed to stand for 6 d at room temperature. After which, a crystallized product was formed that was filtered, washed with ethanol (2x5 ml), dried and recrystallized in a mixture of methanol/ethanol (1:1) to afford the orange crystals of the title compound (m.p. 469-471 K).

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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 S1 0.76662 (18