2-(2,5-Dichloro-benzene-sulfonamido)-3-methyl-butanoic acid.

The structure of the title compound, C(11)H(13)Cl(2)NO(4)S, shows one sulfonamide-O atom to lie almost in the plane of the benzene ring [C-C-S-O = -178.7 (2) °] and the other to one side [C-C-S-O = -49.4 (3)°]. Lying to the other side is the amine residue, which occupies a position almost perpendicular to the plane [C-S-N-C = 70.2 (2)°]; the carb-oxy-lic acid group is orientated to lie over the benzene ring. In the crystal, the appearance of an 11-membered {⋯OH⋯OCOH⋯OC(2)NH} synthon, which features the hy-droxy group forming both donor (to a carbonyl-O) and acceptor (from the amine-H) inter-actions, leads to the formation of a supra-molecular chain along the a axis. Chains are connected in the crystal structure by C-H⋯O contacts.