6-Hydroxy-5-(1-naphthalenylazo)-2-naphthalenesulfonic acid sodium salt

Naphthalen-1-amine diazo, and 6-Hydroxynaphthalene-2-sulfonic acid coupling.

red. Slightly soluble in water for blue-ray red, soluble in ethanol red. In the strong sulfuric acid as dark blue, a red brown after diluted. In water solution to join strong hydrochloric acid for red light brown; Add thick sodium hydroxide solution into a brown.