Allura Red AC Chemical Structure

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What is Allura Red?

Allura red AC is a naphthalenesulfonic acid. It is a red azo dye and was initially introduced in the United States as a substitute for Amaranth dye. It is used as a food dye and has the E number E129. It is typically provided as its red sodium salt, but it can also be used as the calcium and potassium salts.

Macsen Laboratories is the leading manufacturer and supplier of Allura Red dye with ISO certification.
Name of Product Allura Red
IUPAC Name disodium;6-hydroxy-5-[(2-methoxy-5-methyl-4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonate
Synonyms Allura Red AC; Food Red No. 40; C.I. Food Red 17; Curry red; FD&C Red No. 40; Fancy Red
CAS No 25956-17-6
Molecular Formula C18H14N2Na2O8S2
Molecular Weight 496.4g/mol
Color Index No 16035
Pubchem CID 33258


SR. No Criteria Limit/Specification
1 Appearance (form) Solid Powder
2 Appearance (color) Dark Red to Maroon
3 Melting Point > 300 °C (572 °F; 573 K)
4 Solubility Soluble in Water, Glycerol and Propylene Glycol
5 Log P log Kow = -0.55 (estimated)
6 Decomposition When heated to decomposition, it emits very toxic fumes of nitrogen and sulfur oxides


  • The FDA has authorized the use of Allura Red AC in cosmetics, pharmaceuticals, and foods in the United States ( FD&C Red 40).
  • It is used as a coloring agent in food items such as frozen treats, powder mixes, gelatin products, cotton candies, icings, jellies, sauces, baked goods, dairy products and even in beverages.
  • It is used in some tattoo inks.
  • It is occasionally used for strictly aesthetic purposes to color pharmaceutical pills, like as the antihistamine fexofenadine.


Q. Is Allura Red AC polar?

Allura Red AC dye is polar in nature.

Q. Is Allura Red bad for you?

Presently, no health concerns have been reported as such with the use of Allura Red dye. Hence, it is considered relatively safe for use.

Q. Is Allura Red vegan?

Allura Red dye is vegan because it is not animal-derived.

Q. What is Allura Red made from?

Allura Red AC dye is manufactured by coupling diazotized 5-amino-4-methoxy-2-toluenesulfonic acid with 6-hydroxy-2-naphthalene sulfonic acid in an azo coupling reaction.

Q. Is Allura Red banned in the UK?

For safety reasons, the United Kingdom and Switzerland have banned the use of Allura Red (Red 40).


Food Dyes | An overview of all the dyes currently used in Food

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