6-Amino-4-hydroxy-2-naphthalenesulfonic acid Chemical Properties

Boiling point:

458℃[at 101 325 Pa]

Density 

1.4338 (rough estimate)

vapor pressure 

0Pa at 25℃

refractive index 

1.6500 (estimate)

storage temp. 

Keep in dark place,Sealed in dry,Room Temperature

pka

-0.20±0.40(Predicted)

form 

powder to crystal

color 

White to Gray to Brown

Water Solubility 

4.5g/L(hot water)

InChIKey

HBZVNWNSRNTWPS-UHFFFAOYSA-N

LogP

-1.39

CAS DataBase Reference

90-51-7(CAS DataBase Reference)

EPA Substance Registry System

2-Naphthalenesulfonic acid, 6-amino-4-hydroxy- (90-51-7)

Safety Information

Hazard Codes 

C

Risk Statements 

34

Safety Statements 

26-27-28-36/37/39-45

RIDADR 

UN 2585 8/PG 3

WGK Germany 

1

RTECS 

QK1295250

HS Code 

2922.21.5000

Toxicity

LD50 intraperitoneal in mouse: > 500mg/kg

MSDS

• Language:English Provider:SigmaAldrich

6-Amino-4-hydroxy-2-naphthalenesulfonic acid Usage And Synthesis

Chemical Properties

2-Amino-8-hydroxynaphthalene-6-sulfonic acid [90-51-7]. (6-amino-4-hydroxynaphthalene-2-sulfonic acid), g acid, C10H9NO4S, Mr 239.2, is obtained as white or gray crystals which are only sparingly soluble in water even at 100℃ (0.4%). The sodium salt dissolves readily in water to form solutions that exhibit a blue fluorescence. Coupling with diazo compounds is usually carried out under acid conditions and occurs in the 1-position; coupling in the 7-position can be effected in alkaline solution.

Uses

6-Amino-4-hydroxy-2-naphthalenesulfonic Acid is used in the synthesis of mono-azo dyes for application towards synthetic fibers. Also used in the synthesis of dyes with high technical properties for silk. The so-called g acid is an important component in azo dyes; coupling can be carried out under acid or alkaline conditions. The oamino azo configuration obtained under acid conditions leads to high lightfastness of special importance in monoazo acid red dyes for wool and polyamide, such as C.I. Acid Reds 37, 57, and 266.

Production Methods

2-Aminonaphthalene-6,8-disulfonic acid liquor is added over 16 h to 70 % sodium hydroxide at 190℃, while the water is allowed to evaporate to maintain the temperature. The reaction mixture is then heated for a further 6 h. Completion of the reaction is indicated by a workedup sample giving identical titers for both diazotization and coupling. The batch is diluted with water, acidified, and heated at 75℃ to expel sulfur dioxide. The product is filtered off at 55℃ and washed with warm water; yield is 84 %.
An improved process with 90 % yield is claimed by feeding concentrated 2-aminonaphthalene-6,8-disulfonic acid dipotassium salt liquor and caustic soda liquor simultaneously into the fusion reactor.

Flammability and Explosibility

Not classified

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