4-(4-Bromobenzenesulfonamido)benzoic acid

The title compound, C13H10BrNO4S, belongs to the sulfonamide class of organic compounds. The two aromatic rings are inclined at 34.30 (15)° to one another, and the carboxyl substituent lies in the plane of the benzene ring to which it is bound (maximum deviation = 0.004 Å). In the crystal structure, charactersitic carboxylic acid dimers are formed through O—H⋯O hydrogen bonds. These dimers are linked into rows down a by N—H⋯O interactions. Additional C—H⋯O contacts further stabilize the structure, and a close Br⋯Br(x, −y + 1, −z + 1) contact of 3.5199 (9) Å is also observed.

The title compound, C 13 H 10 BrNO 4 S, belongs to the sulfonamide class of organic compounds. The two aromatic rings are inclined at 34.30 (15) to one another, and the carboxyl substituent lies in the plane of the benzene ring to which it is bound (maximum deviation = 0.004 Å ). In the crystal structure, charactersitic carboxylic acid dimers are formed through O-HÁ Á ÁO hydrogen bonds. These dimers are linked into rows down a by N-HÁ Á ÁO interactions. Additional C-HÁ Á ÁO contacts further stabilize the structure, and a close BrÁ Á ÁBr(x, Ày + 1, Àz + 1) contact of 3.5199 (9) Å is also observed.
MNA acknowledges the Higher Education Commission, Pakistan, for providing a PhD Scholarship under the PIN 042-120607-PS2-183 scheme and also acknowledges Professor Dr M. Nawaz Tahir, Chairman, Department of Physics, University of Sargodha, Pakistan, for his kind guidance in crystallography.

Comment
Sulfonamide derivatives have been reported as antibacterial agents (Pandya et al., 2003) as well as enzyme inhibitors. The studies also revealed that aromatic sulfonamides are inhibitors of the growth of tumor cells (Supuran, & Scozzafava, 2000).
Herein we report the structure of the title compound I, Fig, 1, as a continuation of our work on the synthesis and structure of sulfonamides (Arshad, Khan & Zia-ur-Rehman et al., 2008a) and thiazine related heterocycles (Arshad, Tahir et al., 2008b).
The structure of the title compound I can be compared with that of 4-(tosylamino)benzoic acid (Nan and Xing, 2006) which differs only in respect that I has bromo substituent in the para position instead of methyl group. The carboxylic acid substituent lies in the plane of the benzene ring to which it is bound (maximum deviation 0.004 Å) and the phenyl rings (C1-C6) and (C7-C12) are oriented at an angle of 34.30 (0.15) ° to each other. Bond lengths in the molecule are normal (Allen et al., 1987). The carboxylic acid substituent forms dimers via intermolecular O-H···O hydrogen bonds. These dimers are further linked through N-H···O hydrogen bonds between the N-H and the oxygen of the sulfonyl group (SO 2 ) along the a axis. Moreover the structure is further stabilized by C-H···O intermolecular interactions, Table 1, by forming seven and ten membered ring motifs Fig. 3.

Experimental
The title compound was synthesized following the method (Deng & Mani, 2006). and recrystallized from ethanol for X-ray studies.

Refinement
All H-atoms were positioned geometrically and refined using a riding model with d(C-H) = 0.93 Å, U iso =1.2U eq (C) for aromatic 0.82 Å, U iso = 1.5U eq (O) for the OH group and 0.86 Å, U iso = 1.2U eq (N) for the NH group. Fig. 1. The structure of (I) with displacement ellipsoids for the non-hydrogenatoms drawn at the 50% probability level.