Acid Red 18 (Ponceau 4R, Cochineal Red A, CI 16255) is one of the rarely allowable azo synthetic dyes and is often used in dyeing drink, food, tobacco, textile, medicine and cosmetics.

The name describes the structure of the molecule 

• "Ponceau" is a French term referring to a bright red color. 
• "4R" specifically identifies this variant within the Ponceau dye family.

Description of raw materials used in production 

• Naphthalenesulfonics - Provide the aromatic core necessary for the dye structure.
• Azo compounds - Elements that contain the azo group (N=N) characteristic of azo dyes.

Synthesis process 

• Diazotization: An aromatic amine is treated to form a diazonium salt.
• Azo coupling: The diazonium salt is reacted with a naphthalenesulfonic derivative. During this reaction, the characteristic azo bond (N=N) of azo dyes is formed.
• Isolation and purification: After coupling, the dye is isolated, purified from impurities, and then dried.

Industrially it comes in the form of red powder.

Food

Ingredient dye included in the list of European food additives as E124

The FAO/WHO Joint Expert Committee on Food Additives (JECFA) in 1983 and the Scientific Committee for Food (SCF) in 1984 established an ADI of 0-4,0 mg/kg body weight/day for Ponceau 4R

In May 2010, the FSA (Food Standard Agency) established guidelines for certain dyes, including E124: "When using the colours listed below in food and drink there is a requirement (subject to a limited number of exemptions) to include the additional information that „name or E number of the colour(s)‟: may have an adverse effect on activity and attention in children"

Cosmetics

It is a restricted ingredient IV/35 (CI 16255) as a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009 and III/192 (Acid Red 18; Acid Red 18 Aluminum Lake).

Significant studies

Ponceau 4R is used as a coloring agent in many different products, such as food, drinks, medicines, cosmetics and tobacco. However, ponceau 4R also shows carcinogenic, teratogenic and mutagenic behavior in high doses.  In this work, standard Raman, theoretical Raman and surface-enhanced Raman scattering (SERS) spectra have been used to investigate ponceau 4R. More specifically, density functional theory (DFT) calculations have been used to calculate the optimized Raman spectrum of ponceau 4R at the B3LYP/6-31G(d) level. This has provided a better understanding of the optimized geometry and vibrational frequencies of this dye. In addition, the experimental spectrum of ponceau 4R has been compared with the theoretical spectrum; good agreement was obtained. Finally, it has shown that using SERS the detection limit of the ponceau 4R solution can be as low as 5 μg/mL. This has been achieved by SERS measurements of ponceau 4R on a substrate of gold nanoparticles. The SERS peaks at 1030, 1236, 1356 and 1502 cm(-1) were chosen as index for semi-quantitative analysis, showing that the SERS technique provided a useful ultrasensitive method for the detection of ponceau 4R (1).

The synthetic food dyes studied were rose bengal (RB), phroxine (PL), amaranth, erythrosine B (ET), allura red, new coccine, acid red (AR), tartrazine, sunset yellow FCF, brilliant blue FCF, and indigo carmine...  Result suggests that superoxide anions, originating on dyes by light irradiation, must attack drug-metabolizing enzymes. It is possible that red cosmetics containing phloxine, erythrosine, or rose bengal react with proteins on skin under lighting and may lead to rough skin (2).

Dyes are one of the most important existing pollutants in textile industrial wastewater. These compounds are often toxic, carcinogenic, and mutagenic to living organisms, chemically and photochemically stable, and non-biodegradable. Acid red 18 is one of the azo dyes that are currently used in the textile industries (3).

Typical features of Ponceau 4R commercial dye:

The most relevant studies on this chemical compound have been selected with a summary of their contents:

OPINION OF THE SCIENTIFIC COMMITTEE ON COSMETIC PRODUCTS AND NON-FOOD PRODUCTS INTENDED FOR CONSUMERS CONCERNING ACID RED 18 

CI 16255 studies

• Molecular Formula: C₂₀H₁₁N₂Na₃O₁₀S₃
• Molecular Weight: 604.461 g/mol
• UNII: Z525CBK9PG
• CAS: 2611-82-7    11138-24-2  12000-58-7  161628-34-8  39470-82-1  39471-00-6  51811-48-4  247151-36-6
• EC Number: 220-036-2
• PubChem Substance ID 329751631
• MDL number MFCD00004084
• Beilstein Registry Number 4122340

Synonyms: 

• Ponceau 4R
• E 124
• C.I. Food Red 7
• New coccine
• Acid red 18
• 2611-82-7
• Food Red No. 102
• Victoria Scarlet 3R
• SX Purple
• Zolfosol
• Brilliant Scarlet 3R
• Cochineal Red A
• Food Red 102
• Coccin Red
• New Coccin
• Purple Red
• Atul Scarlet F
• Crimson SX
• Purple SX
• Acid Ponceau 4R
• Acid Scarlet 4R
• Java Scarlet 3R
• Neklacid Red 3R
• Neklacid Red 4R
• Scarlet 4R
• Ponceau 4RE
• Ponceau 4RF
• Ponceau 4RT
• Scarlet 4RA
• C.I. Acid Red 18
• C.I. Acid Red 28
• Cochineal Red 4R
• Kiton Scarlet 4R
• Acid Scarlet 3RZ
• Acid Brilliant Scarlet 3R
• Cilefa Ponceau 4R
• Fenazo Scarlet 3R
• Coccine
• HD Ponceau 4R
• Neucoccin
• Neucoccin [German]
• Ponceau 4RE.FQ
• Colacid Ponceau 4R
• Food Red 7
• Hexacol Ponceau 4R
• Pontacyl Scarlet RR
• Acilan Scarlet V3R
• Victoria Scarlet Red
• Strawberry Red
• Brilliant Ponceau 4R
• Brilliant Ponceau 5R
• Brilliant Scarlet 4R
• Certicol Ponceau 4RS
• Curol Bright Red 4R
• Brilliant Ponceau 3R
• HD Ponceau 4R Supra
• L-Rot 4 [German]
• Strawberry Red A Geigy
• Acid Scarlet 3R
• 1,3-Naphthalenedisulfonic acid,7-hydroxy-8-[(4-sulfo-1-naphthalenyl)azo]-, trisodium salt
• sodium (E)-7-hydroxy-8-((4-sulfonatonaphthalen-1-yl)diazenyl)naphthalene-1,3-disulfonate
• trisodium 7-hydroxy-8-[(4-sulfonato-1-naphthyl)diazenyl]naphthalene-1,3-disulfonate
• trisodium 7-oxo-8-[(4-sulfonato-1-naphthyl)hydrazono]naphthalene-1,3-disulfonate
• trisodium 7-oxo-8-[(4-sulfonatonaphthalen-1-yl)hydrazinylidene]naphthalene-1,3-disulfonate
• trisodium;7-hydroxy-8-[(E)-(4-sulfonatonaphthalen-1-yl)diazenyl]naphthalene-1,3-disulfonate
• tripotassium 7-hydroxy-8-[2-(4-sulfonatonaphthalen-1-yl)diazen-1-yl]naphthalene-1,3-disulfonate
• Brilliant Scarlet
• Atul Acid Scarlet 3R
• Brilliant Ponceau 3RF
• Brilliant Ponceau 4RC
• Food Red Number 102
• Naphthalene Scarlet 4RS
• Naphthalene Ink Scarlet 4R
• Sugai Brilliant Scarlet 3R
• Cerven kysela 18 [Czech]
• Edicol Supra Ponceaux 4 RS
• Rakuto Brilliant Scarlet 3R
• Aizen Brilliant Scarlet 3RH
• Cerven kosenilova A [Czech]
• Bucacid Brilliant Scarlet 3R
• L-Red 4
• Edicol Supra Ponceau 4R
• Eurocert Cochineal Red A
• Hidacid Fast Scarlet 3R
• Red Dye No. 102
• Cochenillerot A [German]
• Acidal Bright Ponceau 3R
• Coccine nouvelle [French]
• Kochineal Red A for Food
• Edicol Supra Ponceau 4RS
• New Coccine Extra Pure A
• Edicol Supra Ponceaux 4RS
• New Coccine Red No. 102
• San-ei Brilliant Scarlet 3R
• Takaoka Brilliant Scarlet 3R
• 1578 Red
• Naphthalene Scarlet 4R
• Daishiki Brilliant Scarlet 3R
• Schultz Nr. 213 [German]
• CCRIS 2652
• Calcocid Brilliant Scarlet 3RN
• Cochineal Red A Specially Pure
• Hispacid Brilliant Scarlet 3RF
• Cerven potravinarska 7 [Czech]
• Rouge de cochenille A [French]
• C.I. Acid Red 18 (VAN)
• HSDB 5537
• Kayaku Food Colour Red No. 102
• New Coccine Extra Conc. A Export
• Symulon Acid Brilliant Scarlet 3R
• NSC 4301
• EINECS 220-036-2
• Brilliant Ponceau 4RC Specially Pure
• Victoria Scharlach 4 R Extra [German]
• Z525CBK9PG
• Brilliant Scarlet 3R (Biological stain)
• C.I. 185
• CI 16255
• Kayaku Acid Brilliant Scarlet 3R
• Ponceau 4R aluminum lake
• C.I. Acid Red 18, Trisodium Salt
• MFCD00004084
• Trisodium 1-(1-naphthylazo)-2-hydroxynaphthalene-4',6,8-trisulphonate
• 1-(4-Sulpho-1-naphthylazo)-2-naphthol-6,8-disulphonic acid, trisodium salt
• 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-, trisodium salt
• 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-[(4-sulfo-1-naphthalenyl)azo]-, trisodium salt
• 7-Hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-1,3-naphthalenedisulfonic acid trisodium salt
• 51811-48-4
• Cochenillerot A
• Coccine nouvelle
• 7-Hydroxy-8-((4-sulfo-1-naphthalenyl)azo)-1,3-naphthalenedisulfon- ic acid, trisodium salt
• trisodium 7-hydroxy-8-[(Z)-(4-sulfonatonaphthalen-1-yl)diazenyl]naphthalene-1,3-disulfonate
• Cerven kysela 18
• trisodium (8E)-7-oxo-8-[(4-sulfonatonaphthalen-1-yl)hydrazinylidene]naphthalene-1,3-disulfonate
• Cerven kosenilova A
• Rouge de cochenille A
• Schultz Nr. 213
• Cerven potravinarska 7
• L-Rot 4
• Victoria Scharlach 4 R Extra
• trisodium 7-hydroxy-8-[(Z)-(4-sulfonato-1-naphthyl)diazenyl]-1,3-naphthalenedisulfonate
• Scarlet 3R
• Ponceau 4 R
• Food red No.102
• Acid Red 18,
• AC1NSE7S
• AC1O4BTW
• 1,3-Naphthalenedisulfonic acid, 7-hydroxy-8-(2-(4-sulfo-1-naphthalenyl)diazenyl)-, sodium salt (1:3)
• EC 220-036-2
• Ponceau 4RC (E124)
• DTXSID9021213
• Ponceau 4R, analytical standard
• CTK4J4923
• CTK8I9811
• New Coccine, Dye content 75 %
• C20H11N2O10S3.3Na
• HY-D0193
• Ponceau 4R (C.I. 16255)
• AKOS000282867
• AKOS015903123
• AKOS024319577
• ACM2611827
• CS-5346
• LS-7686
• AN-18880
• C.I. Acid Red 18, trisodium salt (8CI)
• F0140
• N0309
• C20344
• J-016263
• I14-18670

References__________________________________________________________________

(1) Xie Y, Li Y, Sun Y, Wang H, Qian H, Yao W. Theoretical calculation (DFT), Raman and surface-enhanced Raman scattering (SERS) study of ponceau 4R.   Spectrochim Acta A Mol Biomol Spectrosc. 2012 Oct;96:600-4. doi: 10.1016/j.saa.2012.06.055. Epub 2012 Jul 20.

(2) Mizutani T Toxicity of xanthene food dyes by inhibition of human drug-metabolizing enzymes in a noncompetitive manner.   J. Environ Public Health. 2009;2009:953952. doi: 10.1155/2009/953952. 

(3) Jorfi S, Barkhordari MJ, Ahmadi M, Jaafarzadeh N, Moustofi A, Ramavandi B. Photodegradation of Acid red 18 dye by BiOI/ZnO nanocomposite: A dataset.   Data Brief. 2017 Nov 24;16:608-611. doi: 10.1016/j.dib.2017.11.068.