7-hydroxynaphthalene-1-sulphonic acid Chemical Properties

Boiling point:

335.63°C (rough estimate)

Density 

1.4643 (rough estimate)

refractive index 

1.5400 (estimate)

pka

0.26±0.40(Predicted)

EPA Substance Registry System

1-Naphthalenesulfonic acid, 7-hydroxy- (132-57-0)

7-hydroxynaphthalene-1-sulphonic acid Usage And Synthesis

Chemical Properties

Colorless crystals. Easily soluble in water and alcohol. 2-Hydroxynaphthalene-8-sulfonic acid [132-57-0]. (7-hydroxynaphthalene-1-sulfonic acid), crocein acid, Bayer’s acid, C10H8O4S, Mr 224.23, is more soluble in water than 2-hydroxynaphthalene-6-sulfonic acid and cannot readily be isolated. Its salts are also more soluble than their 2,6-analogues and are difficult to isolate. On evaporation of its solutions, the free acid (2-Hydroxynaphthalene-8-sulfonic acid) decomposes to 2-naphthol. Coupling with diazo compounds takes place in the 1-position, but reaction is hindered by the peri-sulfonic acid group so that concentrated conditions and sometimes catalysts are required. Above 60 ℃, sulfuric acid converts 2-Hydroxynaphthalene-8-sulfonic acid into 2-hydroxynaphthalene-6-sulfonic acid; sulfonation then proceeds further to give the 6,8-disulfonic acid. Amination (Bucherer reaction) gives 2-aminonaphthalene8-sulfonic acid.

Uses

Used as an intermediate of acid dyes and direct azo dyes.

Preparation

7-hydroxynaphthalene-1-sulphonic acid was prepared by sulfonation of 2-naphthol with 98% sulfuric acid at low temperature.

7-hydroxynaphthalene-1-sulphonic acid(132-57-0)Related Product Information

• Dipotassium 7-hydroxynaphthalene-1,3-disulphonate
• 2-NAPHTHOL-8-SULFONIC ACID POTASSIUM SALT
• disodium 7-hydroxy-8-[[4'-[[4-[[(p-tolyl)sulphonyl]oxy]phenyl]azo][1,1'-biphenyl]-4-yl]azo]naphthalene-1,3-disulphonate
• ACID RED 114
• PONCEAU 6R
• 2-Naphthol-6,8-disulfonic acid
• CROCEIN SCARLET 7B
• Acid Red 18
• DIRECT SCARLET B
• CRYSTAL PONCEAU 6R
• Acid Red 73
• DIRECT FAST RED 3B
• Acid Orange 10
• 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-3,6,8-TRISULFONIC ACID
• CONGO VIOLET
• CYANOL GREEN
• 2-NAPHTHOL-8-SULFONIC ACID SODIUM SALT