6-Hydroxynaphthalene-2-sulphonic acid Property

Melting point:

>300 °C(lit.)

Boiling point:

335.63°C (rough estimate)

Density 

1.4643 (rough estimate)

refractive index 

1.5400 (estimate)

pka

0.41±0.40(Predicted)

CAS DataBase Reference

93-01-6(CAS DataBase Reference)

NIST Chemistry Reference

2-Naphthalenesulfonic acid, 6-hydroxy-(93-01-6)

EPA Substance Registry System

2-Naphthalenesulfonic acid, 6-hydroxy- (93-01-6)

Safety

Hazard Codes 

Xi

Risk Statements 

36/37/38

Safety Statements 

26-36

WGK Germany 

3

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.

6-Hydroxynaphthalene-2-sulphonic acid Chemical Properties,Usage,Production

Chemical Properties

2-Hydroxynaphthalene- 6 -sulfonic acid [93-01-6]. (6-hydroxynaphthalene-2-sulfonic acid), Schaeffer acid, C10H8O4S, Mr 224.23, is readily soluble in water, from which it can be recrystallized as the monohydrate (mp 129℃). The sodium salt is sparingly soluble in cold water (1.7 %) but forms a 30 % solution at 80℃. Coupling with diazo compounds results in substitution in the 1-position as does treatment with bromine, nitrous acid, or oleum. Fusion with potassium hydroxide gives 2,6-dihydroxynaphthalene, amination gives 2- aminonaphthalene-6-sulfonic acid, and sulfonation (20 % oleum, 25℃) results in 2-hydroxynaphthalene-1,6-disulfonic acid.

Uses

2-Hydroxynaphthalene-6-sulfonic acid is used as a coupling component for a wide range of azo dyes, e.g., C.I. Acid Orange 12, C.I. Food Yellow 3, and C.I. Food Orange 2. It is also used as an intermediate for more highly substituted dye components and synthetic tanning agents. The 1-nitroso derivative forms an iron complex (C.I. Acid Green 1) which was formerly used as a wool dye.

Preparation

2-Naphthol is added to a mixture of sulfuric acid and sodium sulfate, and the reaction is continued at 90 C for 12 h. After pouring the reaction mixture into water, the sodium salt of the product is precipitated by addition of salt and filtered at 60℃ to separate the isomers.