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

The asymmetric unit of the title compound, C15H16ClNO2S, contains two independent moleules. The conformation of the N—H bonds are anti to the ortho-methyl groups in the sulfonyl benzene rings of both the molecules, while the N—H bonds are anti to the ortho- and meta-methyl groups in the aniline ring of one of the molecules and syn in the other. Furthermore, the torsion angles of the C—SO2—NH—C segments in the two molecules of are −66.8 (3) and 70.3 (3)°. The sulfonyl and the aniline benzene rings are oriented at angles of 44.1 (1) and 39.7 (1)° in the two molecules. In the crystal, pairs of N—H⋯O hydrogen bonds link the molecules into dimers.

The asymmetric unit of (I) contains two independent moleules. The conformation of the N-H bonds are anti to the ortho-methyl groups in the sulfonyl benzene rings of both the molecules, while, the N-H bonds are anti to the ortho-and meta-methyl groups in the anilino benzene ring of one of the molecules and syn in the other.
The torsion angles of the C-SO 2 -NH-C segments in the two molecules of (I) are -66. The sulfonyl and the aniline benzene rings in (I) are tilted relative to each other by 44.1 (1)° in molecule 1 and 39.7 (1)°i n molecule 2, compared to the values of 86.6 (2)° and 83.0 (2)° in the two independent molecules of (II), and 76.6 (2)° in molecule 1 and 70.7 (2)° in molecule 2 of (III).
The other bond parameters in (I) are similar to those observed in (II), (III) 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 as dimers (Fig. 2).

Experimental
The solution of m-chlorotoluene (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-methyl-4-chlorobenzenesulfonylchloride was treated with 2,3-dimethylaniline 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-(2,3-dimethylphenyl)-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.

supplementary materials sup-2 Refinement
The H atoms of the NH groups were located in a difference map and later restrained to N-H = 0.86 (2) %A. 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.