7-hydroxynaphthalene-1-sulphonic acid Property

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)

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H315Causes skin irritation

H319Causes serious eye irritation

Precautionary statements

P264Wash hands thoroughly after handling.

P264Wash skin thouroughly after handling.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P302+P352IF ON SKIN: wash with plenty of soap and water.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

P321Specific treatment (see … on this label).

P332+P313IF SKIN irritation occurs: Get medical advice/attention.

P362Take off contaminated clothing and wash before reuse.

7-hydroxynaphthalene-1-sulphonic acid Chemical Properties,Usage,Production

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.