Basic information Safety Supplier Related

2-Naphthol-6,8-disulfonic acid

Basic information Safety Supplier Related

2-Naphthol-6,8-disulfonic acid Basic information

Product Name:
2-Naphthol-6,8-disulfonic acid
Synonyms:
  • 7-Hydroxy-1,3-naphthalenedisulfonicacid
  • 7-hydroxynaphthalene-1,3-disulfonic acid hydrate
  • 7-hydroxy-3-naphthalenedisulfonicacid
  • 7-hydroxynaphthalene-1,3-disulphonicacid
  • -Naphthol-disulphonicacid
  • 2-NAPHTHOL-6,8-DISULFONIC ACID
  • 7-hydroxynaphthalene-1,3-disulfonic acid
  • 2-Hydroxynaphthalene-6,8-disulfonicacid
CAS:
118-32-1
MF:
C10H8O7S2
MW:
304.3
EINECS:
204-245-6
Product Categories:
  • Intermediates of Dyes and Pigments
Mol File:
118-32-1.mol
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2-Naphthol-6,8-disulfonic acid Chemical Properties

Boiling point:
415.13°C (rough estimate)
Density 
1.7421 (rough estimate)
refractive index 
1.6000 (estimate)
form 
solid
pka
-0.33±0.40(Predicted)
color 
Off-white
EPA Substance Registry System
1,3-Naphthalenedisulfonic acid, 7-hydroxy- (118-32-1)
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Safety Information

HS Code 
2904100090
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2-Naphthol-6,8-disulfonic acid Usage And Synthesis

Chemical Properties

2-Hydroxynaphthalene-6,8-disulfonic acid [118-32-1]. (7-hydroxynaphthalene-1,3- disulfonic acid), G acid, C10H8O7S2, Mr 304.3: most salts of 55 are more readily soluble in water than those of R acid, with the notable exception of the potassium salt. Sulfonation with 20 % oleum at 100℃ yields 2-hydroxynaphthalene3,6,8-trisulfonic acid. Diazo coupling takes place in the 1-position, although the reaction is sluggish, as in the case of 2-hydroxynaphthalene8-sulfonic acid.

Uses

The G acid is aminated (Bucherer reaction) to give 2-aminonaphthalene-6,8- disulfonic acid and subjected to caustic fusion at 200℃ to yield 2,8-dihydroxynaphthalene-6-sulfonic acid (a precursor of g acid). It is also used as a coupling component for a wide range of azo colorants, e.g., C.I. Acid Orange 10, C.I. Acid Red 187, and C.I. Food Red 7.

Production Methods

2-Naphthol is added to 98 % sulfuric acid at 40℃. Then, 20 % oleum is added over 6 h and the temperature is allowed to rise to 60℃. The reaction is completed by heating for a further 16 h at 60℃ followed by 15 h at 80℃. After the reaction mixture has been poured into water, potassium chloride is added to the hot solution and the batch is cooled slowly to 35℃ before filtering off the crystalline dipotassium salt of G acid and carefully washing out any residual R salt; the yield is 60 %. In addition, R salt can be recovered from the filtrate in 12 % yield after conversion to its sodium salt.

2-Naphthol-6,8-disulfonic acid Preparation Products And Raw materials

Preparation Products

Raw materials

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