A second monoclinic polymorph of N-cyclohexyl-N-ethylbenzenesulfonamide

The crystal structure of the title compound, C14H21NO2S, is a polymorph of the structure reported by Khan et al. [Acta Cryst. (2009), E65, o2867] which is also monoclinic (space group P21/c). The unit cell in the title structure is approximately half the volume of the previously reported polymorph and the asymmetric unit of the title compound contains one molecule rather than two independent molecules in the other polymorph. In the title molecule, the cyclohexane ring is in the typical chair form. In the crystal structure, molecules are linked via weak intermolecular C—H⋯O interactions, forming a chain along the b-axis direction.

The crystal structure of the title compound, C 14 H 21 NO 2 S, is a polymorph of the structure reported by Khan et al. [Acta Cryst. (2009), E65, o2867] which is also monoclinic (space group P2 1 /c). The unit cell in the title structure is approximately half the volume of the previously reported polymorph and the asymmetric unit of the title compound contains one molecule rather than two independent molecules in the other polymorph. In the title molecule, the cyclohexane ring is in the typical chair form. In the crystal structure, molecules are linked via weak intermolecular C-HÁ Á ÁO interactions, forming a chain along the b-axis direction.
As a part of our ongoing research program regarding the synthesis of sulfur containing heterocyclic compounds Zia-ur-Rehman et al. 2009), we, herein report the crystal structure of the title compound as a new polymorph of the structure previously reported by Khan et al. (2009) which is also monoclinic (space group P2 1 /c), but with completely different unit cell constants. The molecular structure of the title compound (I) is shown in Fig. 1. The asymmetric unit contains single molecule instead of two as observed in the previous form. In the molecule of (I), bond lengths (Allen et al., 1987) and bond angles are within the normal ranges. The cyclohexane ring is in the chair form. In the crystal structure, molecule are linked via weak intermolecular C-H···O hydrogen bonds to form chains along the b axis direction.

Experimental
A mixture of N-cyclohexylbenzene sulfonamide (1.0 g, 0.43 mmol), sodium hydride (0.21 g; 0.88 mmoles) and N, N-dimethylformamide (10.0 ml) was stirred at room temperature for half an hour followed by addition of ethyl iodide (0.134 g; 0.86 mmoles). Stirring was continued further for a period of three hours and the contents were poured over crushed ice.
Precipitated product was isolated, washed and crystallized from methanol.

Refinement
All hydrogen atoms were identified in a difference Fourier map. However, they were fixed in ideal positions and treated as riding on their parent atoms. The following distances were used: C methyl = -H 0.98 Å. C aromatic -H 0.95 Å. U(H) was set to 1.2U eq (C) or 1.5U eq (C methyl ). Fig. 1. The molecular structure of (I), with displacement ellipsoids at the 50% probability level. as those based on F, and R-factors based on ALL data will be even larger.