4-Chloro-N-(3,5-dimethylphenyl)benzenesulfonamide

The asymmetric unit of the title compound, C14H14ClNO2S, contains two independent molecules, which are twisted at the S atoms with C—SO2—NH—C torsion angles of −69.4 (7)° and 66.0 (8)°. The sulfonyl and the anilino benzene rings are tilted relative to each other by 49.0 (4) and 61.7 (3)° in the two molecules. In the crystal, the molecules are linked into chains by N—H⋯O hydrogen bonds.

The asymmetric unit of the title compound, C 14 H 14 ClNO 2 S, contains two independent molecules, which are twisted at the S atoms with C-SO 2 -NH-C torsion angles of À69.4 (7) and 66.0 (8) . The sulfonyl and the anilino benzene rings are tilted relative to each other by 49.0 (4) and 61.7 (3) in the two molecules. In the crystal, the molecules are linked into chains by N-HÁ Á ÁO hydrogen bonds.
KS thanks the University Grants Commission, Government of India, New Delhi, for the award of a research fellowship under its faculty improvement program.

Comment
The sulfonamide moieties are the constituents of many biologically important compounds. The hydrogen bonding preferences of sulfonamides have been investigated (Adsmond & Grant, 2001). As a part of our work on the substituent effects on the structures and other aspects of this class of compounds (Gowda et al., 2006(Gowda et al., , 2007Nirmala et al., 2009;Shakuntala et al., 2011a,b), in the present work, the crystal structure of 4-chloro-N-(3,5-dimethylphenyl)-benzenesulfonamide (I) has been determined ( Fig.1). The asymmetric unit of the structure contains two independent molecules. The molecules are twisted at the S atoms with the C-SO 2 -NH-C torsion angles of -69.5 (7)° and 66.1 (8)° in the two molecules, compared to the values of 65.3 (2)° and 54.6 (2)° in the two independent molecules of 4-chloro-N-(2,5-dimethylphenyl)-benzenesulfonamide The sulfonyl and the anilino benzene rings in the two independent molecules of (I) are tilted relative to each other by 49.0 (4)° (molecule 1) and 61.7 (3)° (molecule 2), compared to the values of 59.3 (1)° (molecule 1) and 45.8 (1)° (molecule 2) in (II), -53.8 (3)° and -63.4 (3)° in the two independent molecules of (III), and 54.6 (1)° in (IV) In the title compound the molecules are linked into chains by N-H···O(S) hydrogen bonding (Table 1 and Fig.2).

Experimental
The solution of chlorobenzene (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 4-chlorobenzenesulfonylchloride was treated with 3,5-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 ml).
The resultant 4-chloro-N-(3,5-dimethylphenyl)-benzenesulfonamide was filtered under suction and washed thoroughly with cold water. It was then recrystallized to constant melting point from aqueous ethanol. The compound was characterized by recording its infrared and NMR spectra.
Prism like colourless single crystals used in X-ray diffraction studies were grown in ethanolic solution by slow evaporation at room temperature.

Refinement
The H atoms were positioned with idealized geometry using a riding model with the aromatic C-H = 0.93 Å, methyl C-H = 0.96 Å, N-H = 0.86 Å and were refined with isotropic displacement parameters (set to 1.2 times of the U eq of the parent atom).

supplementary materials sup-2
The residual electron-density features are located in the region of H1A and S1. The highest peak is 1.31 Å from H1A and the deepest hole is 1.09 Å from S1. To improve considerably values of R1, wR2, and GOOF these bad four reflections (4 3 10 2 2 7 2 2 5 2 3 4) were omitted from the refinement.
The crystals available for X-ray studies were of rather poor quality and weak scatterers at high theta value resulting in relatively high R values. Fig. 1. Molecular structure of (I), showing the atom labelling scheme and displacement ellipsoids are drawn at the 50% probability level.