Used primarily as an intermediate in the synthesis of sulfa drugs, particularly carbonic anhydrase inhibitors like acetazolamide and methazolamide. Its dual functional groups allow for sequential reactions, enabling the construction of complex heterocyclic structures in pharmaceuticals. Also employed in the preparation of dyes and fluorescent probes due to its sulfonamide-forming capability. Its reactivity makes it valuable in organic synthesis for introducing sulfonyl and sulfonamide moieties into target molecules.