Sulfonamide

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.

The general formula is R−SO2NR'R" or R−S(=O)2−NR'R", where each R is some organic group; for example, "methanesulfonamide" (where R = methane, R' = R" = hydrogen) is CH3SO2NH2.

In medicine, the term "sulfonamide" is sometimes used as a synonym for sulfa drug, a derivative or variation of sulfanilamide.

[citation needed] A base such as pyridine is typically added to absorb the HCl that is generated.

Sultams are prepared analogously to other sulfonamides, allowing for the fact that sulfonic acids are deprotonated by amines.

[5] An alternative synthesis of sultams involves initial preparation of a linear sulfonamide, followed by intramolecular C-C bond formation (i.e. cyclization), a strategy that was used in the synthesis of a sultam-based deep-blue emitter for organic electronics.