In organic chemistry, the sulfonamide functional group (also spelled sulphonamide) is an organosulfur group with the structure . It consists of a sulfonyl group () connected to an amine group (). Relatively speaking this group is unreactive. 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.
A sulfonamide (compound) is a chemical compound that contains this group. The general formula is or , where each R is some organic group; for example, "methanesulfonamide" (where R = methane, R' = R" = hydrogen) is . Any sulfonamide can be considered as derived from a sulfonic acid by replacing a hydroxyl group () with an amine group.
In medicine, the term "sulfonamide" is sometimes used as a synonym for sulfa drug, a derivative or variation of sulfanilamide. The first sulfonamide was discovered in Germany in 1932.
Synthesis and reactions
Sulfonamides can be prepared in the laboratory in many ways. The classic approach entails the reaction of sulfonyl chlorides with an
amine.
A base such as
pyridine is typically added to absorb the HCl that is generated. Illustrative is the synthesis of sulfonylmethylamide.
The reaction of primary and secondary amines with benzenesulfonyl chloride is the basis of the Hinsberg reaction, a method for detecting primary and secondary amines.
Sulfonamides undergo a variety of acid-base reactions. The N-H bond can be deprotonated. The alkylsulfonamides can be deprotonated at carbon. Arylsulfonamides undergo ortho-lithiation.
Sultams
Sultams are cyclic sulfonamides. Bioactive sultams include the antiinflammatory
ampiroxicam and the anticonvulsant
sulthiame. Sultams are prepared analogously to other sulfonamides, allowing for the fact that sulfonic acids are deprotonated by amines. They are often prepared by one-pot oxidation of disulfides or thiols linked to amines.
[Rassadin, V.; Grosheva, D.; Tomashevskii, A. Sokolov, V. "Methods of Sultam Synthesis" Chemistry of Heterocyclic Compounds 2013, Vol. 49, p39-65. 27. .] 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.
Disulfonimides
The
disulfonimides are of the type with two sulfonyl groups flanking an amine.
As with
sulfinamides, this class of compounds is used as catalysts in
enantioselective synthesis.
Bis(trifluoromethanesulfonyl)aniline is a source of the triflyl () group.
See also
Further reading
-
Greenwood, David. Antimicrobial Drugs: Chronicle of a twentieth century medical triumph (Oxford University Press, 2008) popular history; summary
