2-Aminonaphthalene-8-sulfonic acid [86- 60-2]. (7-aminonaphthalene-1-sulfonic acid), Badische acid, C10H9NO3S, Mr 223.24, crystallizes from water as needles or prisms although only 0.5 % soluble at 100 ℃. Alkalimetal salts are quite soluble in water. Caustic fusion yields 7-amino-1-naphthol, sulfonation in the cold with 20 % oleum gives 2-aminonaphthalene-6,8-disulfonic acid, but nitration gives a mixture of products. 2-Aminonaphthalene-8-sulfonic acid reacts with diazo compounds to form diazoamino compounds rather than coupling to give azo derivatives.
