Naphthalin-2,7-disulfonsure

VerwendenIntermediate for dyes. The disodium salt of 8 gives 2-hydroxynaphthalene-7-sulfonic acid or 2,7-dihydroxynaphthalene by fusion processes. Sulfonation by oleum gives the 1,3,6-trisulfonic acid, and nitration gives 1-nitronaphthalene-3,6- disulfonic acid. In sulfuric acid solution, the disodium salt of naphthalene-2,7-disulfonic acid undergoes an unusual reaction at the 4-position with 4,40 -bis- (dimethylamino)benzhydrol. The resulting condensation product is oxidized with lead dioxide to give the acid basic dye C.I. Acid Green 16.