4-Chloro-N-(3,4-dichlorophenyl)-2-methylbenzenesulfonamide

In the title compound, C13H10Cl3NO2S, the N—C bond in the C—SO2—NH—C segment forms trans and gauche torsion angles with respect to the S=O bonds. Further, the N—H bond in the C—SO2—NH—C segment is anti to the meta-Cl atom in the anilino benzene ring and nearly syn with respect to the ortho-methyl group in the sulfonyl benzene ring. The C—SO2—NH—C torsion angle is −49.4 (2)°. The sulfonyl and aniline benzene rings are tilted relative to each other by 54.6 (1)°. In the crystal, molecules are linked into chains along the c-axis direction by intermolecular N—H⋯O hydrogen bonds.

VZR thanks the University Grants Commission, Government of India, New Delhi, for the award of an RFSMS fellowship.
In (I), the conformation of the N-C bond in the C-SO 2 -NH-C segment has trans and gauche torsions with respect to the S═O bonds. Further, the N-H bond in the C-SO 2 -NH-C segment is anti with respect to the meta-Cl atom in the anilino benzene ring and nearly syn with respect to the ortho-methyl group in the sulfonyl benzene ring. The molecule is bent at the S atom with the C-SO 2 -NH-C torsion angle of -49.42 (23)°, compared to the value of -49.72 (18)° in 4-Chloro-2-methyl-N-(3,4-dimethylphenyl)-benzenesulfonamide (II) (Rodrigues et al., 2011).
The sulfonyl and the aniline benzene rings are tilted relative to each other by 54.6 (1)°, compared to the values of 71.6 (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).
In the crystal, the intermolecular N-H···O hydrogen bonds (Table 1) link the molecules into infinite chains. Part of the crystal structure is shown in Fig. 2.

Experimental
The solution of m-chlorotoluene (10 ml) in chloroform (40 ml) was treated drop wise with chlorosulfonic acid (25 ml) at 273 K. 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-methyl-4-chlorobenzenesulfonylchloride was treated with a stoichiometric amount of 3,4-dichloroaniline 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, 4-chloro-2-methyl-N-(3,4-dichlorophenyl)benzenesulfonamide, was filtered under suction and washed thoroughly with cold water. It was then recrystallized to constant melting point from dilute ethanol (Savitha & Gowda, 2006). Colourless prisms were grown from its ethanol solution by slow evaporation at room temperature. 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 drawn at the 50% probability level.