Used as a key reagent in organic synthesis, particularly in the preparation of sulfonamides and sulfonate esters. It acts as an electrophilic sulfonylating agent, enabling the introduction of the 3-nitrobenzenesulfonyl (nosyl) group to amines and alcohols. This is valuable in peptide synthesis and protecting group chemistry, where the nosyl group can be selectively removed under mild conditions. Its strong electron-withdrawing nitro group enhances reactivity and facilitates purification due to increased crystallinity of products. Also employed in the development of pharmaceuticals and agrochemicals as an intermediate in multi-step syntheses.