1-Aminonaphthalene-4,7-disulfonic acid [85-75-6]. (4-aminonaphthalene-1,6-disulfonic acid), Dahl’s acid III, C10H9NO6S2, Mr 303.3, and its sodium salt are readily soluble in water, but the calcium and barium salts are only sparingly soluble. Conversion to 1-hydroxynaphthalene-4,7-disulfonic acid is achieved by reverse-Bucherer reaction or diazotization and hydrolysis. Sulfonation (35 % oleum, 90℃) yields 1-aminonaphthalene-2,4,7-trisulfonic acid.
?Although separation of 4-aminonaphthalene-1,6-disulfonic acid from the mixture obtained by sulfonation of naphthionic acid is not practicable on a large scale, the 1,4,7-isomer can be obtained directly in high yield by sulfonation of 1-aminonaphthalene-7-sulfonic acid with oleum.
