2-Naphthol-6,8-disulfonic acid
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
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)
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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2-Naphthol-6,8-disulfonic acid(118-32-1)Related Product Information
- PALATINE CHROME GREEN
- Acid Red 18
- disodium 7-hydroxy-8-[[4'-[[4-[[(p-tolyl)sulphonyl]oxy]phenyl]azo][1,1'-biphenyl]-4-yl]azo]naphthalene-1,3-disulphonate
- 2-Naphthol-6,8-disulfonic acid
- PONCEAU 6R
- DIRECT FAST RED 3B
- disodium 8-[[3,3'-dimethoxy-4'-[[4-[[(p-tolyl)sulphonyl]oxy]phenyl]azo][1,1'-biphenyl]-4-yl]azo]-7-hydroxynaphthalene-1,3-disulphonate
- 2-NAPHTHOL-6,8-DISULFONIC ACID DIPOTASSIUM SALT
- 7-hydroxy-1,3-naphthalenesulfonic acid, potassium salt
- ACID RED 114
- DIRECT SCARLET B
- Acid Red 73
- CRYSTAL PONCEAU 6R
- 1-PHENYLAZO-2-NAPHTHOL-6,8-DISULFONIC ACID DISODIUM SALT
- 1-NAPHTHOL-3,8-DISULFONIC ACID DISODIUM SALT
- 6-Amino-1-naphthol-3,5-disulfonic acid,3-amino-8-naphthol-4,6-disulfonic acid,2-amino-5-naphthol-1,7-disulfonic acid
- 1-PHENYLAZO-2-NAPHTHOL-6,8-DISULFONIC ACID DISODIUM SALT
- 1-NAPHTHOL-3,8-DISULFONIC ACID