Ortho Nitro Benzene Sulfonyl Chloride

Ortho Nitro Benzene Sulfonyl Chloride (ONBSC) is an aromatic sulfonyl chloride compound with the molecular formula C₆H₄ClNO₄S and CAS No. 1694-92-4. It appears as a white to yellow crystalline powder and is widely used as a reagent and intermediate in organic synthesis. ONBSC is valued for its ability to introduce sulfonyl protecting groups, particularly in the synthesis of pharmaceuticals, agrochemicals, and specialty dyes. It reacts readily with alcohols and amines to form sulfonate esters and sulfonamides, offering selectivity and stability in multi-step reactions. The nitro group at the ortho position enhances electrophilicity, making it suitable for regioselective transformations. It is moisture-sensitive and must be stored under inert conditions. Indian manufacturers supply ONBSC in technical and high-purity grades, with compliance to ISO and REACH standards. Its versatility and reactivity make it a preferred choice for chemists working on complex molecular frameworks and advanced intermediates.