1-AMINO-2-NAPHTHALENESULFONIC ACID

1-Aminonaphthalene-2-sulfonic acid [81- 06-1]. ortho-naphthionic acid, C10H9NO3S, Mr 223.24, mp 262 – 265℃ (decomp.), is sparingly soluble in cold water but dissolves in hot water to give a 3 % solution. The sodium salt is more readily soluble in water (1.7 % at 20℃ and 10 % at 100℃). The calcium salt is similarly soluble, but the barium salt is almost insoluble.