Database/Hair Dyeing/Acid Yellow 23
Mostly petroleum · ISO 16128

Is Acid Yellow 23 natural?

Mostly not. Tartrazine's pyrazolone-azo aromatic core is petrochemical; its two sulfonate groups and three sodium ions are mineral-derived.

INCI nameAcid Yellow 23
CAS1934-21-0
FormulaC16H9N4Na3O9S2 · 534.4 Da
FunctionHair Dyeing
FeedstockManufactured by diazo coupling of synthetic phenylhydrazine-sulfonic acid…

How we scored it

Tartrazine trisodium salt (known structure, no formula supplied): pyrazolone-azo-bis(benzenesulfonate) core ~305 Da (petrochemical) + 2×sulfonate 160 Da + 3 Na 69 Da (both natural) → 229/534 = 0.43.
What counts. ISO 16128-2 scores the atoms that remain in the final ingredient. Reagents, solvents, catalysts and protecting groups used during manufacture leave no mass behind and are not counted.

Where it comes from

Manufactured by diazo coupling of synthetic phenylhydrazine-sulfonic acid and a pyrazolone derivative, isolated as the trisodium salt. No natural-origin route exists.

In plain English

Tartrazine, a synthetic yellow dye used to colour hair. Its aromatic dye core is petrochemical; its sulfonate and sodium groups come from mineral sources.

CosIng definition: Acid Yellow 23 is classed chemically as a pyrazole colour. It conforms to the formula:

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Structure

2D structure of Acid Yellow 23

trisodium;5-oxo-1-(4-sulfonatophenyl)-4-[(4-sulfonatophenyl)diazenyl]-4H-pyrazole-3-carboxylate

PubChem CID 164825 ↗

References

  1. 1ISO 16128-1:2016 and ISO 16128-2:2017 — Guidelines on technical definitions and criteria for natural and organic cosmetic ingredients and products. ISO, Geneva.
  2. 2Acid Yellow 23. PubChem CID 164825. National Center for Biotechnology Information. pubchem.ncbi.nlm.nih.gov ↗
  3. 3ACID YELLOW 23. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
  4. 4ACID YELLOW 23. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=ACID%20YELLOW%2023