C.I. Direct Red 169, disodium salt

Preparation

(a) M-nitroaniline diazo, in acid conditions and 7-Amino-4-hydroxynaphthalene-2-sulfonic acid coupling, then use glucose and sodium hydroxide solution will nitro reduction; (b) 3-(3-(3-Aminophenyl)-1-oxadiaziridin-2-yl)benzenamine double nitriding, in acid conditions and 7-Amino-4-hydroxynaphthalene-2-sulfonic acid (2 Moore) coupled.

Properties and Applications

dark red. Soluble in water for orange brown, slightly soluble in alcohol. The strong sulfuric acid for dark olive brown, for yellow brown after diluted. The dye solution to join strong hydrochloric acid for dark brown, have precipitation; Add thick sodium hydroxide solution for palm light orange to brown.