5293. Kermesic Acid

Nomenclature

CAS number: 18499-92-8
9,10-Dihydro-3,5,6,8-tetrahydroxy-1-methyl-9,10-dioxo-2-anthracenecarboxylic acid; C.I. Natural Red 3; C.I. 75460.
C16H10O8; mol wt 330.25.
C 58.19%, H 3.05%, O 38.76%.

Description and references

Principle constituent of kermes, one of the oldest known insect dyes. Isoln and characterization: O. Dimroth, Ber. 43, 1387 (1910); O. Dimroth, W. Scheurer, Ann. 399, 43 (1913). Structure: O. Dimroth, R. Fick, Ann. 411, 315 (1916). Revised structure: D. D. Gadgil et al., Tetrahedron Lett. 1968, 2223. Synthesis: D. W. Cameron et al., Chem. Commun. 1978, 688; eidem, Aust. J. Chem. 34, 2401 (1981).

Chemical structure

Properties

Dark red rosettes from acetic acid, mp >320° (dec). Absorption max: 276, 312, 498 nm (log ε 4.52, 4.12, 3.96). Slightly sol in cold water; sol in hot water (yellowish-red soln). Violet-red in conc H2SO4, turning blue on addn of boric acid. Violet in aq NaOH.

Use

As brilliant scarlet dye.