2-Aminonaphthalene-3,6,8-trisulfonic acid [118-03-6]. (7-aminonaphthalene-1,3,6- trisulfonic acid), C10H9NO9S3, Mr 383.36, and its disodium salts are soluble in water, but the dipotassium salt is much less soluble. Reduction with zinc dust and alkali results in 2-aminonaphthalene-3,6-disulfonic acid, and caustic fusion at 240℃ gives 2-amino-8-hydroxynaphthalene-3,6-disulfonic acid.
2-Aminonaphthalene-6,8-disulfonic acid is sulfonated with 65 % oleum at 125℃ for 12 h in the presence of anhydrous sodium sulfate. After quenching and liming out, the hot solution of calcium salt is basified with sodium carbonate and the resulting solution of the trisodium salt is used directly for caustic fusion to give 2-amino-8-hydroxynaphthalene-3,6-disulfonic acid.
