Direct Blue 72

Preparation

aniline diazo, and 5-Aminonaphthalene-2-sulfonic acid first coupling, again diazo, and 5-Aminonaphthalene-2-sulfonic acid second coupling, its product to diazo, in alkaline conditions and 7-Amino-4-hydroxynaphthalene-2-sulfonic acid third coupling.

Properties and Applications

dark blue to navy blue. Moderate soluble in water for violet black, also moderate soluble in alcohol. The strong sulfuric acid in dark green light for blue, diluted red for sauce. The dye solution to join strong hydrochloric acid have dark blue precipitation; Add thick sodium hydroxide solution generation dark purple precipitation. Mainly used for cellulose fiber dyeing, also used for paper color