Used primarily as an intermediate in organic synthesis, particularly in the production of pharmaceuticals and agrochemicals. It serves as a key reagent in the preparation of sulfonyl-containing compounds, including sulfa drugs and other bioactive molecules. Its reactivity allows for the introduction of chlorosulfonyl and ester functionalities, enabling further transformations such as cyclizations and chain extensions. Commonly employed in the synthesis of heterocyclic compounds due to its ability to participate in ring-forming reactions. Also utilized in the development of functionalized polymers and specialty materials where sulfonyl groups enhance thermal or chemical stability.