Used primarily as an intermediate in the synthesis of pharmaceuticals and agrochemicals. It plays a key role in the preparation of sulfa drugs and herbicides due to its ability to introduce sulfonyl functional groups into organic molecules. Its reactivity makes it valuable in forming sulfonamides, which are important in antimicrobial agents. Also utilized in the development of dyes and pigments for enhanced color stability. Common in research settings for constructing complex molecules requiring selective chlorination and sulfonylation.