title: 4,4′-Diamino-2,2′-stilbenedisulfonic acid
text: # 4,4′-Diamino-2,2′-stilbenedisulfonic acid
  
  4,4′-Diamino-2,2′-stilbenedisulfonic acid is the organic compound with the formula $(H_2NC_6H_3SO_3H)_2C_2H_2.$ It is a white, water-soluble solid. Structurally, it is a derivative of trans-stilbene, containing amino and sulfonic acid functional groups on each of the two phenyl rings.
  
  The compound is a popular optical brightener for use in laundry detergents.
  
  It is produced by reduction of 4,4′-dinitro-2,2′-stilbenedisulfonic acid with iron powder.
  
  