Naphthalene-2,7-disulfonic acid

CAS NO.：92-41-1
Empirical Formula: C10H8O6S2
Molecular Weight: 288.3
MDL number: MFCD00035734
EINECS: 202-154-6
SAFETY DATA SHEET (SDS)
Update Date: 2024-08-08 18:06:34

What is Naphthalene-2,7-disulfonic acid?

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.

The Uses of Naphthalene-2,7-disulfonic acid

Intermediate for dyes.

Definition

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

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.

Purification Methods

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

Properties of Naphthalene-2,7-disulfonic acid

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 for Naphthalene-2,7-disulfonic acid

Signal word	Danger
Pictogram(s)	Corrosion Corrosives GHS05
GHS Hazard Statements	H314:Skin corrosion/irritation
Precautionary Statement Codes	P260:Do not breathe dust/fume/gas/mist/vapours/spray. P280:Wear protective gloves/protective clothing/eye protection/face protection. P310:Immediately call a POISON CENTER or doctor/physician.