Sulfonamide
Sulfonamide is a simple, important chemical group in organic molecules. It combines a sulfonyl unit (S(=O)2) with an amine (NR2), giving the general structure R-SO2-NR2. This group is fairly unreactive, and sulfonamides often form crystals, which makes them useful for turning amines into solid, easy-to-identify derivatives.
The general formula is R-SO2-NR'R'' (each R can be an organic group). For example, methanesulfonamide is CH3SO2NH2. A sulfonamide can be thought of as a sulfonic acid that has had its OH replaced by an amine. In medicine, “sulfonamide” often refers to sulfa drugs, which are derivatives of sulfanilamide. The first sulfonamide was discovered in Germany in 1932.
How sulfonamides are made: the classic method is to react a sulfonyl chloride with an amine, usually with a base like pyridine to absorb the HCl produced. The Hinsberg reaction uses benzenesulfonyl chloride to react with primary or secondary amines and helps distinguish between them.
Sulfonamides can participate in many acid–base reactions. The N–H bond can be deprotonated, and certain sulfonamides can lose protons from carbon or undergo ortho-lithiation in the aryl cases.
Sultams are cyclic sulfonamides. Some bioactive examples are ampiroxicam (an anti‑inflammatory) and sulthiame (an anticonvulsant). Sultams are made in similar ways to other sulfonamides, often starting from a linear sulfonamide and forming a ring, or by one-pot oxidation of disulfides or thiols linked to amines.
Disulfonimides are a related class with two sulfonyl groups around an amine and are used as catalysts in enantioselective synthesis. Bis(trifluoromethanesulfonyl)aniline is a common reagent that provides the triflyl group (CF3SO2).
This page was last edited on 2 February 2026, at 13:27 (CET).