Direct brown 33 (C.I. 35520)

Preparation

4-(4-Aminophenyl)benzenamine double nitriding, in alkaline conditions and 4-Amino-5-hydroxynaphthalene-2,7-disulfonic acid?coupling, and then and phenol coupling, product to diazo, and 6-Amino-4-hydroxynaphthalene-2-sulfonic acid? diazo, and Benzene-1,3-diamine coupled to a product matches

Properties and Applications

dark red light brown. Soluble in water for the opacity of the purple brown, and adequate soluble in ethanol, acetone and soluble fiber element, insoluble in other organic solvents. The strong sulfuric acid for blue-ray in purple to red light navy, dilute for purple after brown; In nitric acid completely dissolved in for red light gray; In strong hydrochloric acid in completely dissolved not for red light gray. The dye solution to join strong hydrochloric acid with brown precipitation; Join rare hydrochloric acid for orange brown; Add 10% sodium hydroxide solution for yellow light brown.