Naphthalene-2,7-disulfonic acid Chemical Properties

Melting point:

199°C

Boiling point:

400.53°C (rough estimate)

Density 

1.6867 (rough estimate)

refractive index 

1.6950 (estimate)

storage temp. 

2-8°C

pka

-0.33±0.40(Predicted)

CAS DataBase Reference

92-41-1(CAS DataBase Reference)

EPA Substance Registry System

2,7-Naphthalenedisulfonic acid (92-41-1)

Safety Information

RIDADR 

1759

HazardClass 

8

PackingGroup 

III

HS Code 

2904100090

Naphthalene-2,7-disulfonic acid Usage And Synthesis

Chemical Properties

White, crystalline solid.Soluble in water. Combustible. Naphthalene-2,7-disulfonic acid [92- 41-1]. C10H8O6S2, Mr 288.28; the sodium salt of Naphthalene-2,7-disulfonic acid is much more soluble than that of the 2,6- isomer but can be isolated and purified by precipitation of the calcium salt at lower temperature followed by recrystallization.

Uses

Intermediate for dyes. The disodium salt of 8 gives 2-hydroxynaphthalene-7-sulfonic acid or 2,7-dihydroxynaphthalene by fusion processes. Sulfonation by oleum gives the 1,3,6-trisulfonic acid, and nitration gives 1-nitronaphthalene-3,6- disulfonic acid. In sulfuric acid solution, the disodium salt of naphthalene-2,7-disulfonic acid undergoes an unusual reaction at the 4-position with 4,40 -bis- (dimethylamino)benzhydrol. The resulting condensation product is oxidized with lead dioxide to give the acid basic dye C.I. Acid Green 16.

Production Methods

The 2,7-disulfonic acid is always the main product of high-temperature sulfonation of naphthalene, but at 160 C it converts slowly to an equilibrium mixture containing ca. 30 % of the 2,6-isomer. Crystallization of the pure product from conventional sulfonation is difficult, and alternative processes, (for example, reaction of naphthalene vapor with sulfur trioxide in the gas phase at 220 C) are said to give a purer product.

Definition

ChEBI: A naphthalenesulfonic acid in which the sulfo groups are attached to positions 2 and 7 of the naphthalene ring.

Purification Methods

Crystallise the acid from conc HCl. The disulfonamide has m 273o (from EtOH). [Beilstein 11 II 119, 11 III 463.]

Naphthalene-2,7-disulfonic acid(92-41-1)Related Product Information

• Naphthalene
• Naphthalene-2-sulfonic acid
• Sodium 1-naphthalenesulfonate
• Sodium xylenesulfonate
• ACID RED 26
• CHROMOTROPE 2B
• 1-(2-ARSONOPHENYLAZO)-2-HYDROXY-3,6-NAPHTHALENE-DISULFONIC ACID SODIUM SALT OCTAHYDRATE
• ARSENAZO I
• ACID RED 1
• CHROMOTROPE 2R
• 1,5-NAPHTHALENE DISULFONIC ACID DISUDIUM SALT,1,5-NAPHTHALENE DISULFONIC ACID SODIUM SALT
• SPADNS
• ACID VIOLET 5
• ACID VIOLET 7
• 1-NITROSO-2-NAPHTHOL-3,6-DISULFONIC ACID DISODIUM SALT
• Mordant Blue 13
• ARSENAZO III DISODIUM SALT
• 3-Hydroxy-4-[[4-(phenylazo)phenyl]azo]naphthalene-2,7-disulfonic acid disodium salt