1-(2-Pyridylazo)-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)
C15H11N3O 249.27 CAS RN®: 85-85-8.-Stable, orange-red crystals. Soluble in alcohol and in hot solutions of dilute alkalies; slightly soluble in water.
MELTING RANGE (741): between 140° and 142°,
Sensitiveness: Add 0.1 mL of a 1 in 1000 solution of it in alcohol to a mixture of 10 mL of water and 1 mL of a buffer solution prepared by mixing 80 mL of 0.2 M acetic acid and 20 mL of sodium acetate solution (8.2 in 100), and mix. To this solution add 1 mL of a mixture of 1 mL of cupric sulfate TS and 2 mL of water, and mix: the color changes from yellow to red.
