Used primarily as an intermediate in the synthesis of sulfa drugs and other pharmaceuticals. It plays a key role in the preparation of saccharin, an artificial sweetener, by serving as a precursor in the chlorosulfonation process. Also utilized in the production of dyes and agrochemicals due to its ability to introduce sulfonyl chloride functional groups into organic molecules. Its reactivity makes it valuable in forming sulfonamide derivatives, which are common structural elements in many biologically active compounds.