Co-grinding sulfadimidine [4-amino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide] with several aromatic carboxylic acids in the solid state produces 1 : 1 hydrogen bonded cocrystals which are identical to those obtained from reaction between the components in solution. The kinetics of solid state formation of selected cocrystals have been measured using X-ray powder diffraction. Sulfadimidine selectively cocrystallizes with 2-aminobenzoic acid when the latter is present in binary mixtures of acids. Solid state reaction of the cocrystal sulfadimidine·2-hydroxybenzoic acid with 2-aminobenzoic acid results in elimination of 2-hydroxybenzoic acid and formation of the cocrystal sulfadimidine·2-aminobenzoic acid.

For each of the well-known co-crystal formers, isonicotinamide and nicotinamide, a new polymorph, obtained during attempted co-crystallisation experiments, has been fully characterized and its stability relationship with previously reported forms established.