2-(2-Iodobenzenesulfonamido)acetic acid

The title compound, C8H8INO4S, is a halogenated sulfonamide, a medicinally important class of organic compounds. In the crystal structure, intermolecular O—H⋯O hydrogen bonds involving the carboxylic acid groups form characteristic centrosymmetric dimers. These dimers are further linked through centrosymmetric dimeric N—H⋯O interactions involving the amido H atom and a sulfonyl O atom. This leads to the formation of a ribbon-like polymer structure propagating in the b direction.

The title compound, C 8 H 8 INO 4 S, is a halogenated sulfonamide, a medicinally important class of organic compounds. In the crystal structure, intermolecular O-HÁ Á ÁO hydrogen bonds involving the carboxylic acid groups form characteristic centrosymmetric dimers. These dimers are further linked through centrosymmetric dimeric N-HÁ Á ÁO interactions involving the amido H atom and a sulfonyl O atom. This leads to the formation of a ribbon-like polymer structure propagating in the b direction.
MNA acknowledges the Higher Education Commission, Pakistan, for providing a PhD Scholarship under PIN 042-120607-PS2-183.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SU2093).  (Pandya et al., 2003). As a continuation of our studies on the synthesis of thiazine related compounds (Arshad et al., 2008a,b,c,d) we present here the structure of the title compound.

Structure Reports Online
The molecular structure of the title compound is illustrated in Fig. 1. We have previously reported on the crystal structures of the non-halogenated analogue of the title compound, 2-(phenylsulfonamido)acetic acid, (Arshad et al., 2008b), and the K + and Na + salts of 2-iodobenzenesulfonates (Arshad et al., 2008a,c). The bond lengths and angles in the title compound are similar to those reported there and are within normal ranges (Allen et al., 1987).
In the crystal structure intermolecular O-H···O hydrogen bonds involving the carboxylic acid groups form characteristic centrosymmetric dimers. These dimers are further linked through centrosymmetric intermolecular N-H···O interactions involving the amido H atoms and a sulfonyl O atom (Fig. 2). This leads to the formation of a ribbon-like polymer structure propagating along the b axis. This arrangement is very similar to that observed in the non-halogenated analogue mentioned above.

Experimental
The title compound was synthesized following the literature method (Deng & Mani, 2006). Glycine methyl ester hydrochloride (207 mg, 1.653 mmol) was dissolved in distilled water (5 ml). The pH of the solution was maintained at 8-9 using 1M, Na 2 CO 3 solution. 2-Iodo benzene sulfonyl chloride (500 mg, 1.653 mmol) was then added to the solution, which was stirred at room temperature until all the 2-iodo benzene sulfonyl chloride had been consumed. During the reaction the pH was again strictly maintained at 8-9 using 1M, Na 2 CO 3 . On completion of the reaction the pH was adjusted 1-2, using 1N HCl under vigorous stirring. The precipitate obtained was filtered off, washed with distilled water and dried. Crystals of the title compound were obtained by recrystallisation from methanol.

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles 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.