FD&C RED #40 or E129 or Allura Red AC is a chemical compound, a dye azo-derivative, water-soluble. (FDA clearance in 1971).

The name describes the structure of the molecule.

• FD&C stands for "Food, Drug, and Cosmetic" and refers to dyes and pigments that have been approved by the United States Food and Drug Administration (FDA) for use in foods, drugs, and cosmetics.
• Red No. 40, also known as Allura Red AC, is a synthetic red dye produced from petroleum. It is one of the most commonly used food dyes.
• Lake refers to an insoluble version of a dye. "Lake" dyes are often used in products that require color stability

Description of raw materials used in production. 

• The raw materials utilized in the synthesis of Allura Red AC typically involve naphthalenesulfonate, phthalic anhydride, and benzenesulfonic acid among others.

Step-by-step summary of industrial production process.

• Preparation of Raw Materials. Raw materials are prepared and purified for use in the synthesis reaction.
• Synthesis Reaction. Raw materials undergo reactions in a controlled environment to form Allura Red AC dye.
• Purification. The crude dye is purified through various steps to remove impurities and other undesired components.
• Drying and Granulation. The dye is then dried and formed into a granular form for ease of use and transportation.

Form and color. FD&C Red No. 40 is a crystalline powder, water-soluble, and ranges in color from red to orange.

Commercial applications.

Food Industry. Widely used to color foods and beverages, providing a distinctive red hue.

Cosmetics and Personal Care Products. Applied in various products like lipsticks and shampoos to provide bright and appealing colors.

Pharmaceuticals. Used to color syrups, tablets, and capsules for easy differentiation and aesthetic reasons.

It has many synonyms, among which the most common is Red 40 or Allura Red AC and, in the list of dyes, CI 16035.

Safety

The US FDA (Food and Drug Administration) has approved the use of Red No. 40 and considers it generally safe when used according to guidelines. However, there are some concerns and studies suggesting it may cause allergic reactions in some people

The problem with azo dyes (monoazo or diazo) is photocatalytic degradation leading to oxidation and the subsequent formation of impurities such as aromatic amines, some of which have carcinogenic activity. (1)

Allura Red AC Studies

• Molecular Formula: C₁₈H₁₄N₂Na₂O₈S₂
• Molecular Weight: 496.416 g/mol
• UNII: WZB9127XOA
• CAS: 25956-17-6  64553-31-7  66813-73-8
• EC Number: 247-368-0
• PubChem Substance ID 329755751
• MDL number MFCD00059526
• Colour Index Number 16035

Synonyms:

• Allura Red
• Allura red AC dye
• C.I. Food Red 17
• Food red 17
• Japan Food Red No. 40
• FD and C Red No. 40
• FD & C Red no. 40
• CCRIS 3493
• CI 16035
• HSDB 7260
• E129
• CI 16035
• Food Red No. 40
• FD&C Red No. 40
• Curry red
• Fancy Red
• Allura Red 40
• FDC Red 40
• Red No. 40
• FDC Red 40 dye
• Food Red No. 17
• AC1O1BOF
• DSSTox_CID_4436
• FD and C Red No.40
• EC 247-368-0
• DSSTox_RID_77395
• DSSTox_GSID_24436
• Sodium 6-hydroxy-5-((2-methoxy-5-methyl-4-sulfonatophenyl)diazenyl)naphthalene-2-sulfonate
• 6-Hydroxy-5-[2-(2-methoxy-5-methyl-4-sulfophenyl)diazenyl]-2-naphthalenesulfonic Acid Sodium Salt
• disodium (5E)-5-[(2-methoxy-5-methyl-4-sulfonatophenyl)hydrazinylidene]-6-oxonaphthalene-2-sulfonate
• 6-Hydroxy-5-[(6-methoxy-4-sulfo-m-tolyl)azo]-2-naphthalenesulfonic Acid Disodium Salt
• disodium (5Z)-5-[(2-methoxy-5-methyl-4-sulfonatophenyl)hydrazinylidene]-6-oxonaphthalene-2-sulfonate
• disodium;(5Z)-5-[(2-methoxy-5-methyl-4-sulfonatophenyl)hydrazinylidene]-6-oxonaphthalene-2-sulfonate
• disodium;6-hydroxy-5-[(E)-(2-methoxy-5-methyl-4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonate
• 2-Naphthalenesulfonic acid, 6-hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-, disodium salt
• Disodium 6-hydroxy-5-((6-methoxy-4-sulfo-m-tolyl)azo)-2-naphthalenesulfonate
• 2-Naphthalenesulfonic acid, 6-hydroxy-5-((6-methoxy-4-sulfo-m-tolyl)azo)-, disodium salt
• Disodium 6-hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-2-naphthalenesulfonate
• Disodium 6-hydroxy-5-((2-methoxy-4-sulphonato-m-tolyl)azo)naphthalene-2-sulphonate
• 2-Naphthalenesulfonic acid, 6-hydroxy-5-(2-(2-methoxy-5-methyl-4-sulfophenyl)diazenyl)-, sodium salt (1:2)
• 2-Naphthalenesulfonic acid, 6-hydroxy-5-[2-(2-methoxy-5-methyl-4-sulfophenyl)diazenyl]-, sodium salt (1:2)
• disodium 6-hydroxy-5-[(E)-(2-methoxy-5-methyl-4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonate
• SCHEMBL324089
• SCHEMBL340786
• C18H14N2Na2O8S2
• CHEMBL3188816
• DTXSID4024436
• Disodium 6-hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-2-naphthalene- sulfonate
• Disodium 6-hydroxy-5-[(2-methoxy-5-methyl-4-sulfophenyl)azo]-2-naphthalenesulfonate
• 2-Naphthalenesulfonic acid, 6-hydroxy-5-[(2-methoxy-5-methyl-4-sulfophenyl)azo]-, disodium salt
• 6-Hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-2-naphthalene- sulfonic acid, disodium salt

References________________________________________________________________________

(1) Barros, W. R., Steter, J. R., Lanza, M. R., & Motheo, A. J. (2014). Degradation of amaranth dye in alkaline medium by ultrasonic cavitation coupled with electrochemical oxidation using a boron-doped diamond anode. Electrochimica Acta, 143, 180-187.

 Kobun Rovina, Shafiquzzaman Siddiquee and Sharifudin M. Shaarani  Extraction, Analytical and Advanced Methods for Detection of Allura Red AC (E129) in Food and Beverages Products  Front Microbiol. 2016 May 27;7:798. doi: 10.3389/fmicb.2016.00798.