English name: 4,4 '- Diaminodiphenylethene-2,2' - disulfonic acid
CAS RN： 81-11-8
EINECS number: 201-325-2
Molecular formula: C₁₄H₁₄N₂O₆S₂
Molecular weight: 370.4008
Melting point:> three hundred and twenty-five
Water solubility:< 0.1 g/100 mL at 23 C
Appearance: Slightly yellow, delicate needle shaped
Structural formula:
Physical and chemical properties: Light yellow paste or powder, soluble in ethanol and ether, insoluble in water, easily soluble in alkaline solutions. Easy to oxidize into red color, while possessing the properties of aromatic acids and amines.
Quality and technical indicators
Appearance: Dry, light yellow powder; Wet product, light yellow paste like substance.
Total amino value (based on the total amount of paste)%:>= 45.0；
Dry total amino value (calculated based on the total amount of dried samples)%: 95.0;
Alkali insoluble content (based on the total amount of paste)%:<= 0.08；
Alkali insoluble substances (based on the total amount of dried samples)%:<= 01；
Content of benzyl compounds (based on the total sample amount)%:<= zero point two five
Main purpose:
Used for producing fluorescent whitening agents, direct frozen yellow G and direct yellow R, and as insecticides.

Synthesis method
It is formed by sulfonation of para nitrotoluene into para nitrotoluene ortho sulfonic acid, followed by catalytic oxidation to 4,4 '- dinitrodistyrene disulfonic acid, and then reduction.

Main purpose
Used for making fluorescent whitening agents and direct dyes. As a dye intermediate, DSD acid is the main raw material for producing the styrene series fluorescent whitening agent VBL; It is also an important intermediate for direct dyes and reactive dyes. It can produce hundreds of varieties such as direct frozen yellow G, direct bright yellow 4R, active tender yellow KD-3G, and sun resistant orange F3G. It can also be used as a pest control agent.

Storage method
This product should be stored in a sealed, cool, dark and dry place.
Packaged in wooden or iron barrels lined with plastic bags. 50kg per barrel. Store in a cool and ventilated warehouse, sealed and stored. The storage period is six months. Store and transport according to regulations for toxic chemicals.

Nature and stability
Toxic and irritating to the skin. Should avoid accidental ingestion and direct contact with the human body. Operators should wear appropriate labor protection equipment.