title: Naphthol AS
text: # Naphthol AS
  
  Naphthol AS is an organic compound with the formula $C_{10}H_6(OH)C(O)NHC_6H_5.$ It is the anilide of 3-hydroxy-2-carboxynaphthalene. Many analogous compounds are known, designated with a differing suffix. For example, in Naphthol AS-OL, the aryl substituent on nitrogen is $C_6H_4-2-OCH_3.$ These compounds are used as coupling partners in the preparation of some azo dyes.
  
  ## History
  
  In 1911, it was found to be a good precursor to dyes for wool by chemists at K. Oehler Anilin- und Anilinfarbenfabrik Offenbach.
  
  