1-Naphthylamine-7-sulfonic acid

1-Naphthylamine-7-sulfonic acid can be obtained by sulfonation, nitration, neutralization, reduction and acid precipitation of naphthalene.

Brown crystalline. 1-Aminonaphthalene-7-sulfonic acid [119- 28-8]. (8-aminonaphthalene-2-sulfonic acid), 1,7-Cleve’s acid, C10H9NO3S, Mr 223.24, is 0.5 % soluble in water at 25℃ and 3 % soluble at 100 ℃. The sodium, potassium, calcium, and magnesium salts are readily soluble in water but the barium salt is only sparingly soluble. Sulfonation with oleum at 50℃ gives 1- aminonaphthalene-4,7-disulfonic acid. Alkali fusion gives 8-amino-2-naphthol, and Bucherer-type hydrolysis gives 1-hydroxynaphthalene-7-sulfonic acid.

Intermediate of dyestuff

8-Amino-2-naphthalenesulfonic acid can be used as a reactant to synthesize:

• Fe₃O₄/sulfonated polyaniline composite material via chemical oxidative polymerization with aniline in the presence of magnetite (Fe₃O₄) nanoparticles.
• Prismatic crystals of strychnine-8-ammonio-2-naphthalenesulfonate-water by heating with strychnine in water/ethanol solvent mixture.
• 5-amino-9-dialkylamino benzo[a]phenoxazine dyes (Nile blue analogs) by condensation with N-alkyl or N-sulfo-propyl 4-arylazo-substituted 3-hydroxyaniline.

1-Naphthylamine-7-sulfonic acid can be used as a dye intermediate to prepare dyes such as direct light fast blue B2RL, direct light fast red brown RTL, and sulfur blue CV.