N-(4-Chlorophenylsulfonyl)-2-methylpropanamide

In the crystal structure of the title compound, C10H12ClNO3S, the N—C bond in the C—SO2—NH—C segment has a gauche torsion with respect to the S=O bonds. The molecule is twisted at the S atom with a C—S—N—C torsion angle of −62.3 (3)°. The benzene ring and the SO2—NH—CO—C segment form a dihedral angle of 89.3 (1)°. In the crystal, molecules are linked by pairs of N—H⋯O hydrogen bonds into inversion dimers.

In the crystal structure of the title compound, C 10 H 12 ClNO 3 S, the N-C bond in the C-SO 2 -NH-C segment has a gauche torsion with respect to the S O bonds. The molecule is twisted at the S atom with a C-S-N-C torsion angle of À62.3 (3) . The benzene ring and the SO 2 -NH-CO-C segment form a dihedral angle of 89.3 (1) . In the crystal, molecules are linked by pairs of N-HÁ Á ÁO hydrogen bonds into inversion dimers.
BTG thanks the University Grants Commission, Government of India, New Delhi, for a one time grant under its BSR scheme.

Comment
The molecular structures of sulfonamide drugs contain the sulfanilamide moiety (Maren, 1976). The propensity for hydrogen bonding in the solid state, due to the presence of various hydrogen bond donors and acceptors gives rise to polymorphism (Yang & Guillory, 1972). The hydrogen bonding preferences of sulfonamides has also been studied (Adsmond & Grant, 2001). The nature and position of substituents play a significant role on the crystal structures of this class of compounds. As part of our work on the effects of substituents on the structures and other aspects of N-(aryl)-amides (Arjunan et al., 2004), (Gowda et al., 2007), N-(aryl)-arylsulfonamides (Gowda et al., 2003) and N-(arylsulfonyl)acetamides , Shakuntala et al., 2011, in the present work, the crystal structure of N-(4-chlorophenylsulfonyl)-2,2-dimethylacetamide (I) has been determined. The N-C bond in the C-SO 2 -NH-C segment has gauche torsion with respect to the S═O bonds. The molecule is twisted at the S-atom with a C-S-N-C torsion angle of -62.3 (3)°, compared to the values of -72.5 (2)° in N-(4-chlorophenylsulfonyl)-2,2-dichloroacetamide (II)  and (Shakuntala et al., 2011).
Further, the dihedral angle between the benzene ring and the SO 2 -NH-CO-C segment in (I) is 89.3 (1)°, compared to the values of 79.7 (1)° in (II) and 87.4 (1)° in (III).
In the crystal structure, the moleucles are connected into centrosymmetrically dimers by intermolecular N-H···O hydrogen bonding ( Table 1). Part of the crystal structure is shown in Fig. 2.

Experimental
The title compound was prepared by refluxing 4-chlorobenzenesulfonamide (0.10 mole) with an excess of 2,2-dimethylacetyl chloride (0.20 mole) for about an hour on a water bath. The reaction mixture was cooled and poured into ice cold water. The resulting solid was separated, washed thoroughly with water and dissolved in warm dilute sodium hydrogen carbonate solution. The title compound was reprecipitated by acidifying the filtered solution with glacial acetic acid. It was filtered, dried and recrystallized from ethanol. The purity of the compound was checked by determining its melting point.
It was further characterized by recording its infrared spectra.
Plate like colorless single crystals of the title compound used in X-ray diffraction studies were obtained from a slow evaporation of an ethanolic solution of the compound.

Refinement
The H atom of the NH group was located in a difference map and later restrained to the distance N-H = 0.86 (2)  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. Displacement ellipsoids are drawn at the 50% probability level.

N-(4-Chlorophenylsulfonyl)-2-methylpropanamide
Crystal data  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.