A monoclinic polymorph of chlorothiazide

Abstract

A new polymorph of the diuretic chlorothiazide, 6-chloro-1,1-dioxo-2H-1,2,4-benzothiazine-7-sulfonamide, C7H6ClN3O4S2, is described. Crystallized from basic aqueous solution, this monoclinic polymorph is found to be less thermodynamically favoured than the known triclinic polymorph and to feature only N—H...O type intermolecular hydrogen bonds as opposed to the N—H...O and N—H...N type hydrogen bonds found in the P1 form.

Keywords

• crystal structure
• polymorphism
• pharmaceutical