4-Chloro-N-(4-chlorophenyl)-2-methylbenzenesulfonamide

In the title compound, C13H11Cl2NO2S, the conformations of the N—C bonds in the C—SO2—NH—C segment have gauche torsions with respect to the S=O bonds. Further, the conformation of the N—H bond is syn to the ortho-methyl group in the sulfonyl benzene ring. The torsion angle of the C—SO2—NH—C segment in the molecule is 55.0 (2)°. The two benzene rings are tilted relative to each other by 67.0 (1)°. In the crystal, intermolecular N–H⋯O hydrogen bonds link the molecules into infinite column-like chains.


Comment
As part of a study of the substituent effects on the crystal structures of N-(aryl)-arylsulfonamides (Gowda et al., 2009a,b;2010), in the present work, the structure of 4-chloro-2-methyl-N-(4-chlorophenyl)benzenesulfonamide (I) has been determined (Fig. 1). The conformations of the N-C bonds in the C-SO 2 -NH-C segment have gauche torsions with respect to the S═O bonds. Further, the conformation of the N-H bond in the C-SO 2 -NH-C segment is syn to the ortho-methyl group in the sulfonyl benzene ring. The sulfonyl and the aniline benzene rings in (I) are tilted relative to each other by 67.0 (1)°, compared to the values of 86.6 (2)° and 83.0 (2)° in the two independent molecules of (II), 45.5 (2)° in (III) and 70.9 (1)° in (IV).
In the crystal, the intermolecular N-H···O hydrogen bonds (Table 1) link the molecules via inversion-related dimers, into infinite column like chains. Part of the crystal structure is shown in Fig. 2.

Experimental
The solution of m-chlorotoluene (10 cc) in chloroform (40 cc) was treated dropwise with chlorosulfonic acid (25 cc) 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-methyl-4-chlorobenzenesulfonylchloride was treated with 4-chloroaniline 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 cc). The resultant solid 4-chloro-2-methyl-N-(4-chlorophenyl)-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).
The rod like colorless single crystals used in X-ray diffraction studies were grown in ethanolic solution by slow evaporation at room temperature.

Refinement
The H atom of the NH group was located in a difference map and later restrained to N-H = 0.85 (1) Å. The other H atoms were positioned with idealized geometry using a riding model with C-H = 0.93-0.96 Å. All H atoms were refined with isotropic displacement parameters (set to 1.2 times of the U eq of the parent atom). Fig. 1. Molecular structure of (I), 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.