4-Aminodiphenylamine-2-sulfonic Acid

4-Aminodiphenylamine-2-sulfonic acid is an organic compound with the molecular formula C₁₂H₁₂N₂O₃S and a molecular weight of 264.30 g/mol. Structurally, it consists of two aromatic rings connected by an amine (-NH-) bridge, with one ring substituted by an amino group (-NH₂) at the para position and a sulfonic acid group (-SO₃H) at the ortho position. This compound typically appears as a brownish or off-white crystalline powder and is soluble in water, especially under alkaline conditions. It plays a significant role as an intermediate in the manufacture of azo dyes, where it acts as a coupling component due to the reactivity of its amino and sulfonic acid groups. These characteristics make it especially useful in the textile and pigment industries. While it is an important chemical in dye synthesis, proper handling is essential as it may cause irritation to the skin, eyes, and respiratory system. It should be stored in a cool, dry place and used with appropriate protective equipmen