Used as an intermediate in the synthesis of sulfa drugs and other biologically active compounds. Its reactive chlorosulfonyl group allows for easy attachment to amines or alcohols, making it valuable in pharmaceutical development. Commonly employed in the preparation of sulfonamide-based inhibitors targeting enzymes such as carbonic anhydrase. Also utilized in the production of dyes and functional polymers due to its ability to introduce sulfonamide linkages into larger molecular frameworks.