Selective formation of hydrogen bonded cocrystals between a sulfonamide and aromatic carboxylic acids in the solid state

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.