253. Alizarine Blue

Nomenclature

CAS number: 568-02-5
5,6-Dihydroxynaphtho[2,3-f]quinoline-7,12-dione; 7,8-dihydroxy-5,6-phthalylquinoline; Alizarin Blue R; C.I. 67410.
C17H9NO4; mol wt 291.26.
C 70.10%, H 3.11%, N 4.81%, O 21.97%.

Description and references

Prepn from 3-nitroalizarin, glycerol, and concd sulfuric acid: Auerbach, J. Chem. Soc. 35, 799 (1879); Colour Index vol. 4 (3rd ed., 1971) p 4567.

Chemical structure

Properties

Lustrous brownish violet needles from benzene, mp 268-270°. Practically insol in water; sparingly sol in alc, ether; slightly sol in cold benzene; sol in amyl alcohol, glacial acetic acid, hot benzene.

Use

As indicator in saturated alcoholic soln. pH: pink 0.0 to yellow 1.6; yellow 6.0 to green 7.6.