Iron, 4-[[5-(3,5-dinitrophenyl)azo]-2,4-dihydroxy-3-[(4-nitrophenyl)azo]]-5-hydroxy-2,7-naphthalenedisulfonic acid complex

4-Amino-5-hydroxynaphthalene-2,7-disulfonic acid?diazo, in weak alkali conditions Coupled with resorcinol, 2-Amino-4,6-dinitrophenol diazo, in weak alkali conditions and the single accidentally nitrogen content coupling, its product again with diazo of 4-Nitrobenzenamine weak inorganic acid in the coupling, and then translate to iron complex.

dark red light brown. Mainly used for leather color.