Sulfonamide

A sulfonamide contains a sulfur(VI)-nitrogen linkage of the form $\mathrm{R}-\mathrm{S}{\mathrm{O}}_2-\mathrm{N}{\mathrm{R}}^{\prime }{\mathrm{R}}^{\prime \prime }$. It differs from a carboxamide, whose nitrogen is attached to a carbonyl carbon.

The sulfonyl group strongly influences nitrogen's electronic environment and acid-base behavior. Substituent choice can alter acidity, hydrogen bonding, and molecular recognition, so sulfonamide denotes a functional family rather than one compound.