2-Nitrobenzenesulfonamide (2-Nosyl amide, 2-NsNH2) is an organic compound with the molecular formula C6H6N2O4S. It is a pale yellow to off-white crystalline solid. The molecule features a nitro group and a sulfonamide group attached to a benzene ring, making it a versatile bifunctional building block. Its primary application is in organic synthesis, particularly as a reagent for the protection of amines. The 2-nitrobenzenesulfonyl (2-Ns) group is a widely used protecting group for amines, especially in peptide synthesis and the preparation of complex molecules. It offers advantages such as stability under various conditions and clean deprotection using thiolates. Beyond protection, it serves as a precursor for other sulfonamide derivatives and is used in the synthesis of heterocyclic compounds and pharmaceuticals. As a specialty synthetic intermediate, it is not a commodity chemical but is valued in research and development for constructing nitrogen-containing molecular architectures. Standard safety precautions for handling nitroaromatic and sulfonamide compounds should be observed.