2-Naphthol
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
(Betanaphthol), C10H7OH 144.17 CAS RN®: 135-19-3.-White leaflets or crystalline powder. Discolors on exposure to light. Very slightly soluble in water, soluble in alcohol, in ether, in chloroform, and in solutions of alkali hydroxides.
MELTING RANGE (741): between 121° and 123°.
Solubility in Alcohol: A solution of 1 g in 10 mL of alcohol is complete and colorless or practically so.
Residue on Ignition (Reagent test): not more than 0.05%.
Acidity: Shake 1 g with 50 mL of water occasionally during 15 minutes, and filter: the filtrate is neutral to litmus.
1-Naphthol: Boil 100 mg with 10 mL of water until dissolved, cool, and filter. Add to the filtrate 0.3 mL of 1 N sodium hydroxide and 0.3 mL of 0.1 N iodine: no violet color is produced.
Insoluble in Ammonia (naphthalene, etc.): Shake 500 mg with 30 mL of ammonia TS: the 2-naphthol dissolves completely and the solution is not darker than pale yellow.
