6393. Naphthol Yellow S

Nomenclature

CAS number: 846-70-8
8-Hydroxy-5,7-dinitro-2-naphthalenesulfonic acid disodium salt; Citronin A; Sulfur Yellow S; Acid Yellow S; FD & C Yellow no. 1; Ext. D & C Yellow no. 7; C.I. Acid Yellow 1; C.I. 10316.
C10H4N2Na2O8S; mol wt 358.19.
C 33.53%, H 1.13%, N 7.82%, Na 12.84%, O 35.73%, S 8.95%.

Description and references

Prepn: Colour Index vol. 4 (3rd ed., 1971) p 4004.

Chemical structure

Properties

Greenish yellow powder, sol in water to a yellow soln. The free acid is known as flavianic acid.

Use

Dye for wool, silk.