Crystalline products of tolbutamide decomposition in water after microwave treatment

Abstract

Microwave treatment of a hot water–drug suspension has resulted in the partial decomposition of tolbutamide (form I). Two new crystalline phases were isolated from the precipitate: the n-butylammoniun salt of tolbutamide and the novel polymorph of p-toluenesulfonamide. Their crystal structures were determined by single-crystal X-ray diffraction. The n-butylammoniun salt of tolbutamide is unstable in air and after decomposition crystallizes in the starting form I tolbutamide. The novel polymorph (β) of p-toluenesulfonamide differs from the old one (α) in an unusual arrangement of layers.