Used in organic synthesis to introduce sulfonyl groups into molecules, enhancing reactivity or modifying properties. It serves as a key intermediate in the production of pharmaceuticals, agrochemicals, and dyes. Often employed in the preparation of sulfonamides, which are critical in antibacterial and anti-inflammatory drugs. Also utilized in polymer chemistry to create sulfonated polymers with specific characteristics, such as improved thermal stability or ion-exchange capabilities. Its reactivity makes it valuable in cross-coupling reactions and as a building block for complex organic compounds.