Acid Yellow 128 CAS #51053-43-1

Acid Yellow 128, also known as Neutral Dark Yellow GL and Acid Yellow 2GL, is greenish yellow and appears as a yellowish brown powder. The molecular formula is C_{16} H_{16} N_{4} O_{5} S, and the molecular weight is 376.38.
Acid Yellow 128 is mainly used for dyeing wool, silk, nylon, and vinylon in neutral or weakly acidic dye baths, as well as for direct printing of wool, silk, and nylon fabrics. It can also be used for dyeing leather.
In water, its solution is a light yellow colloid. The dye has the following chemical properties: it is yellow in concentrated sulfuric acid and becomes a light yellow solution after dilution; it does not change color in concentrated hydrochloric acid and becomes a light yellow solution after dilution; it is destroyed in concentrated nitric acid and the residue is yellow; it is light yellow in dilute nitric acid; it is yellow in concentrated sodium hydroxide solution and becomes light yellow after dilution.