8-Aminonaphthalene-1,6-disulfonic acid

1-Aminonaphthalene-3,8-disulfonic acid [129-91-9]. (8-aminonaphthalene-1,6- disulfonic acid), amino epsilon acid, C10H9NO6S2, Mr 303.3, and its sodium salt are very soluble in water, but the barium salt is only sparingly soluble. Reduction with zinc and alkali (or with sodium amalgam) desulfonates to give 1-aminonaphthalene-3-sulfonic acid. The amino group is hydrolyzed by water at 180℃ to give 1-hydroxynaphthalene-3,8-disulfonic acid. Caustic fusion results in 1-amino-8-hydroxynaphthalene-3-sulfonic acid, whereas reaction with 10 % sodium hydroxide at 250℃ produces 1,8-dihydroxynaphthalene-3-sulfonic acid. Amination produces 1,3-diaminonaphthalene-8-sulfonic acid, but the production of 6,8- di(phenylamino)naphthalene-1-sulfonic acid (diphenyl epsilon acid) by reaction with aniline is more important.