Basic information
CAS: 20324-87-2
Molecular formula: C₂₁H₁₆N₂O₉S₂
Molecular weight: 548.45
Product name: 7,7'-(carbonyldiimino)bis[4-hydroxy-2-naphthalenesulfonic acid disodium salt；sodium 6,6'-(1,3-ureylene)bis(1,1'-naphthol)-3,3'-sulfonate
Properties: light grey paste. Soluble in water, easily soluble in alkaline solutions.

Quality index: 
Appearance: grey white or reddish brown uniform powder
Assay: ≥70%
Free J acid: ≤1.5%
Insoluble matter: ≤0.2%
Uses: As intermediate for azo dyes such as direct orange S[1] and direct fast scarlet 4BS[2], and etc.