2,4-Dichloro-N-(2,3-dichlorophenyl)benzenesulfonamide

In the title compound, C12H7Cl4NO2S, the conformation of the N—C bond in the C—SO2—NH—C segment is gauche with respect to the S=O bonds. Further, the N—H bond in the C—SO2—NH—C segment is syn with respect to the ortho-Cl atoms in the aniline and sulfonyl benzene rings. The C—SO2—NH—C torsion angle is −51.98 (18)°. The sulfonyl and aniline benzene rings are tilted by 67.7 (1)° relative to each other. An intramolecular N—H⋯Cl hydrogen bond occurs.


D-HÁ
In (I), the conformations of the N-C bond in the C-SO 2 -NH-C segment is gauche to the S═O bonds. Further, the N-H bond in the C-SO 2 -NH-C segment is syn with respect to the ortho-Cl atoms in the anilino and sulfonyl benzene rings. The molecule is bent at the S atom with the C-SO 2 -NH-C torsion angle of -52.0 (2)°, compared to the value of The sulfonyl and the aniline benzene rings are tilted relative to each other by 67.7 (1)°, compared to the value of 68.9 (1)°i n (II).
The other bond parameters in (I) are similar to those observed in (II) and other aryl sulfonamides (Perlovich et al., 2006;Gelbrich et al., 2007).
The crystal structure exhibits N-H···Cl intramolecular hydrogen bonding. Part of the crystal structure is shown in Fig. 2.

Experimental
The solution of 1,3-dichlorobenzene (10 ml) in chloroform (40 ml) was treated dropwise with chlorosulfonic acid (25 ml) at 0 ° C. After the initial evolution of hydrogen chloride subsided, the reaction mixture was brought to room temperature and poured into crushed ice in a beaker. The chloroform layer was separated, washed with cold water and allowed to evaporate slowly. The residual 2,4-dichlorobenzenesulfonylchloride was treated with 2,3-dichloroaniline in the stoichiometric ratio and boiled for ten minutes. The reaction mixture was then cooled to room temperature and added to ice cold water (100 ml). The resultant solid 2,4-dichloro-N-(2,3-dichlorophenyl)benzenesulfonamide was filtered under suction and washed thoroughly with cold water. It was then recrystallized to constant melting point from dilute ethanol. The purity of the compound was checked and characterized by recording its infrared and NMR spectra (Savitha & Gowda, 2006).
Prism like light pink single crystals used in X-ray diffraction studies were grown in ethanolic solution by slow evaporation at room temperature.

Refinement
The H atoms of the NH groups were located in a difference map and later restrained to N-H = 0.86 (2) Å. The other H atoms were positioned with idealized geometry using a riding model with the aromatic C-H = 0.93Å and methyl C-H = 0.96 Å. All H atoms were refined with isotropic displacement parameters. The U iso (H) values were set at 1.2U eq (C-aromatic, N) and 1.5U eq (C-methyl). Fig. 1. Molecular structure of the title compound, showing the atom labelling scheme and displacement ellipsoids are drawn at the 50% probability level.  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 Rfactors(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.