Carminic acid

Carminic acid[1]
Chemical structure of carminic acid[citation needed]
Ball-and-stick model of carminic acid[citation needed]
Names
IUPAC name
7-(β-D-Glucopyranosyl)-3,5,6,8-tetrahydroxy-1-methyl-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid
Other names
Carminic acid
C.I. Natural Red 4
C.I. 75470
CI 75470
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.013.658
EC Number 215-023-3
E number E120 (colours)
KEGG
UNII
Properties
C22H20O13
Molar mass 492.38 g/mol
Melting point 120 °C (248 °F; 393 K) (decomposes)
Acidity (pKa) 3.39, 5.78, 8.35, 10.27, 11.51[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Carminic acid (C22H20O13) is a red glucosidal hydroxyanthrapurin that occurs naturally in some scale insects, such as the cochineal, Armenian cochineal, and Polish cochineal. The insects produce the acid as a deterrent to predators. An aluminum salt of carminic acid is the coloring agent in carmine. Synonyms are C.I. 75470 and C.I. Natural Red 4.

The chemical structure of carminic acid consists of a core anthraquinone structure linked to a glucose sugar unit. Carminic acid was first synthesized in the laboratory by organic chemists in 1991.[3]

It was previously thought that it contains α-D-glucopyranosyl residue,[1] which was later redetermined to be the β-D-glucopyranosyl anomer.[4]

References

  1. ^ a b Merck Index, 11th Edition, 1989, 1850.
  2. ^ Atabey, Hasan; Sari, Hayati; Al-Obaidi, Faisal N. (28 April 2012). "Protonation Equilibria of Carminic Acid and Stability Constants of Its Complexes with Some Divalent Metal Ions in Aqueous Solution". Journal of Solution Chemistry. 41 (5): 793–803. doi:10.1007/s10953-012-9830-7.
  3. ^ Allevi, P.; et al. (1991). "The First Total Synthesis of Carminic Acid". Journal of the Chemical Society, Chemical Communications. 18: 1319–1320. doi:10.1039/C39910001319.
  4. ^ Fiecchi, Alberto; Galli, Mario Anastasia Giovanni; Gariboldi, Pierluigi (1981-03-01). "Assignment of the β configuration to the C-glycosyl bond in carminic acid". The Journal of Organic Chemistry. 46 (7): 1511–1511. doi:10.1021/jo00320a061. ISSN 0022-3263. Retrieved 2018-12-13.