Carminic acid

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A bright red or dark purple brown powder. Carminic acid is the primary colorant in Cochineal dyestuff. It is a tricyclic compound that is extracted from the dried insects Coccus cacti with water. Carminic acid changes colors with acidity. It is a bright red in neutral solutions, below pH 4.8, it is yellow and above 6.2, it is a deep violet color. Carminic acid is used as a lake pigment for oil colors, as a red dye for photography and as a textile colorant.

Synonyms and Related Terms

Natural Red 4; CI 75470; ácido (Esp.); acido carminico (It.); ácido carmínico (Port.)

Chemical structure

Carminic acid.jpg


  • Combustible.
  • ThermoFisher: SDS

Physical and Chemical Properties

  • Soluble in water, ethanol, concentrated sulfuric acid. Insoluble in ether, benzene, chloroform.
  • UV max in water = 500 nm.
Composition C22H20O13
CAS 1260-17-9
Melting Point 136 C (dec)
Molecular Weight mol. wt. = 492.39

Resources and Citations

  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 1891
  • Thomas B. Brill, Light Its Interaction with Art and Antiquities, Plenum Press, New York City, 1980
  • F. Crace-Calvert, Dyeing and Calico Printing, Palmer & Howe, London, 1876
  • Sigma Dyes, Stains and Natural Pigments, Infrared Library, Nicolet, 1991-1995 Comment: OMNIC: formula= C22H20O13, CAS= 1260-17-9