Direct red 72

Preparation

6-Aminonaphthalene-2-sulfonic acid diazo, and N,N’-bis(4-hydroxy-2-sulfonaphthalene-7-yl)urea coupling, O-Anisidine (0. 6 Moore) and O-Methylaniline (0.4 Moore) diazo, and coupled product matches.

Properties and Applications

red. Soluble in water for colourful red, soluble in ethanol is shallow orange red. The strong sulfuric acid to red light purple, diluted red brown to orange for brown. The dye solution to join strong hydrochloric acid for orange brown; With strong sodium hydroxide solution for red light brown to orange brown.