4-(4-Hydroxy-3,5-dimethylphenylazo)benzenesulfonic Acid

Abstract

In the solid state, the title compound, C 14 H 14 N 2 O 4 S.-H 2 O, exists as two forms: cubes (I) and needles (II). Both kinds of crystal are monohydrates. The dye molecules have the same geometry and are bonded by O-H...O intermolecular hydrogen bonds in both forms: an N + -H...O - intermolecular hydrogen bond in (II) and an N + -H...(O) 2 - bifurcated hydrogen bond in (I).