Alizarin Yellow R CAS# 66676-71-9

Alizarin Yellow R, has a molecular formula of C_{13} H_{9} N_{3} O_{5} and a molecular weight of 287.23.
It is an orange-brown crystal that decomposes at 253-254°C. It is soluble in water and ethanol, slightly soluble in acetone and ethylene glycol ether, and almost insoluble in other organic solvents. Its commercial product is sodium salt (C_{13} H_{8} N_{3} NaO_{5}), which is a brown-yellow powder. When dissolved in water, the solution is brown-yellow.
Alizarin Yellow R is mainly used as an acid-base indicator, and the pH color change range is 10.2 (yellow) to 12.0 (red).
In terms of physical properties, its density is 1.49g/cm³, its melting point is about 250℃, its boiling point is 571.4℃ (760mmHg), its flash point is 299.4℃, and its vapor pressure is 6.74e-14mmHg (25℃).