Database/Colorant/Acid Yellow 73
100% petroleum · ISO 16128

Is Acid Yellow 73 natural?

No. Fluorescein is synthesised from petrochemical phthalic anhydride and resorcinol; no natural-origin atoms remain in the molecule.

INCI nameAcid Yellow 73
CAS2321-07-5
FormulaC20H12O5 · 332.3 Da
FunctionColorant · Hair Dyeing
FeedstockManufactured by acid-catalysed condensation of resorcinol and phthalic…

How we scored it

Fluorescein free acid, C20H12O5, no mineral counter-ion present; entire xanthene-benzofuranone structure is synthetic. 0/332.3=0.0.
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 acid-catalysed condensation of resorcinol and phthalic anhydride, both petrochemical aromatics. There is no commercial natural-extraction route for this dye.

In plain English

A synthetic yellow-orange dye (fluorescein) used to colour hair-dye products. It is manufactured entirely from petrochemical starting materials, not derived from plants.

CosIng definition: Acid Yellow 73 is classed chemically as a fluoran colour. It conforms to the formula:

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Structure

2D structure of Acid Yellow 73

3',6'-dihydroxyspiro[2-benzofuran-3,9'-xanthene]-1-one

PubChem CID 16850 ↗

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 73. PubChem CID 16850. National Center for Biotechnology Information. pubchem.ncbi.nlm.nih.gov ↗
  3. 3ACID YELLOW 73. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
  4. 4ACID YELLOW 73. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=ACID%20YELLOW%2073