In
chemistry, the
sulfonamide functional group (also spelt
sulphonamide) is -S(=O)
2-NH
2, a
sulfonyl group connected to an
amine group. Relatively speaking this group is unreactive. The amine center is no longer basic. The S-N bond is cleaved only with difficulty. Because of the rigidity of the functional group, sulfonamides are typically crystalline. For this reason, the formation of a sulfonamide is a classic method to convert an amine into a crystalline derivative which can be identified by its melting point. Many important drugs contain the sulfonamide group.