pale purple to brown-purple crystalline powder
5-Amino-1-naphthol is used as a coupling component for azo dyes (coupling takes place ortho to the amino or hydroxyl group, or para to the hydroxyl group depending on the pH), and as an intermediate for sulfur dyes.
1-Aminonaphthalene-5-sulfonic acid paste (Section 6.2) is added to molten sodium hydroxide at 200°C, and the reaction is completed by heating slowly to 250°C and maintaining this temperature for 3 h. After dilution and careful neutralization with hydrochloric acid, 5-amino-1-naphthol precipitates in 85 % yield (mp 192°C).
