Used as a sulfonating agent in organic synthesis, particularly in the preparation of sulfonic acid derivatives. It serves as a building block in the development of surfactants, dyes, and pharmaceuticals due to its ability to introduce sulfone or sulfonic acid groups into molecules. Also employed in polymer chemistry to modify resin properties and enhance solubility or ionic character. Its reactivity makes it useful in creating functional monomers for specialty polymers and in electrochemical applications such as battery electrolyte additives.