1,5-Dihydroxy naphthalene Property

Melting point:

259-261 °C (dec.) (lit.)

Boiling point:

246.06°C (rough estimate)

Density 

1.0924 (rough estimate)

vapor pressure 

0-0Pa at 25℃

refractive index 

1.5418 (estimate)

Flash point:

252°C

storage temp. 

Inert atmosphere,Room Temperature

solubility 

0.6g/l

pka

9.28±0.40(Predicted)

form 

Solid

color 

Pale Beige to Very Dark Brown

PH

6 (0.5g/l, H2O, 20℃)

Water Solubility 

Soluble in water.

BRN 

2044951

LogP

1.7-1.82 at 23℃

CAS DataBase Reference

83-56-7(CAS DataBase Reference)

NIST Chemistry Reference

1,5-Naphthalenediol(83-56-7)

EPA Substance Registry System

1,5-Naphthalenediol (83-56-7)

Safety

Hazard Codes 

Xn,N,Xi

Risk Statements 

22-51/53-36-36/37/38

Safety Statements 

22-24/25-61-39-29-26

WGK Germany 

2

RTECS 

QJ4740000

F 

8-21

TSCA 

Yes

HS Code 

29072900

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H302Harmful if swallowed

H319Causes serious eye irritation

Precautionary statements

P264Wash hands thoroughly after handling.

P264Wash skin thouroughly after handling.

P270Do not eat, drink or smoke when using this product.

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

P301+P312IF SWALLOWED: call a POISON CENTER or doctor/physician IF you feel unwell.

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

P337+P313IF eye irritation persists: Get medical advice/attention.

1,5-Dihydroxy naphthalene Chemical Properties,Usage,Production

Chemical Properties

Grey powder 1,5-Naphthalenediol [83-56-7], 1,5-dihydroxynaphthalene, Azurol, C10H8O2, Mr 160.16, forms colorless needles (from aqueous methyl cellosolve). The compound is sublimable, readily soluble in ether and acetone, but only sparingly soluble in water and hydrocarbons. It is oxidized to 5-hydroxy-1,4-naphthoquinone ( juglone) by CrO3. Amination gives 1,5-naphthalenediamine; coupling with diazotized anilines occurs in the 2- or 4-position.

Uses

1,5-Dihydroxynaphthalene is an intermediate of synthetic mordant azo dyes. It is an intermediate used in organic synthesis, pharmaceuticals, dyestuff fields and photograph industry. It is used as a coupling component in azo dyes as exemplified in the metallizable (Cr) wool dye, C.I. Mordant Black 9.

Production Methods

The sodium salt of naphthalene-1,5-disulfonic acid is added gradually to excess 75 % sodium hydroxide. The mixture is heated under pressure to 276℃ over the course of 7 h and the reaction is completed by heating for a further 5 h at this temperature. After precipitation with sulfuric acid, the product is isolated in 90 % yield.

Purification Methods

The diol (~30g) is purified by making into a thick paste with H2O and suspending this in 3L of H2O containing 200mL of EtOH, boiling under reflux for 3hours, cooling to 30o, saturating with SO2, digesting below the boiling point for 1hour and filtering fast through a large hot filter paper. The hot filtrate is poured onto crushed ice whereby the diol (15-20g) separates as colourless needles (m 258o) [Wheeler & Ergle J Am Chem Soc 52 4873 1930]. Recrystallise it from H2O or nitromethane under N2 to avoid oxidation. The dibenzoyl derivative has m 245o (from EtOH). The 5-methoxy-1-naphthol derivative [prepared from the diol in MeOH/HCl (1:30 weight to volume ratio) and set aside at 25o for 9-10days] crystallised from pet ether (m 135-136o) or from CH2Cl2/hexane (needles m 140o) [Bell & McCaffrey Aust J Chem 46 731 1993]. [Beilstein 6 I 477, 6 II 950, 6 III 5265, 6 IV 6554.]