Database/Hair Dyeing/Acid Red 27
Mostly natural · ISO 16128

Is Acid Red 27 natural?

Mostly. The dye chromophore is synthetic, but its three sodium sulfonate groups count as natural mineral-origin mass, giving the same nonzero index as Acid Red 18.

INCI nameAcid Red 27
CAS915-67-3
FormulaC20H11N2Na3O10S3 · 604.5 Da
FunctionHair Dyeing
FeedstockManufactured by diazotising petrochemical naphthylamine/naphthol-sulfonic-acid intermediates and coupling…

How we scored it

3 Na (69 Da) + 3 sulfonate SO3 groups (240 Da) = 309 Da natural mineral mass; synthetic naphthol-azo-naphthalene backbone (295 Da) petrochemical; 309/604=0.51.
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 diazotising petrochemical naphthylamine/naphthol-sulfonic-acid intermediates and coupling them, then neutralising with sodium hydroxide. Only the sodium and sulfonate mass is mineral in origin.

In plain English

A synthetic red dye used in hair colourants; most of the molecule is man-made, though part of its weight comes from mineral sodium and sulfonate salt groups.

CosIng definition: Acid Red 27 is classed chemically as a monoazo colour. It conforms to the formula:

Natural alternatives with the same function

Beta Vulgaris Root Powder 100% natural origin

A powder made by drying and grinding sugar beet root. Used as a natural colorant for hair dye…

 Bismuth Citrate 100% natural origin

A salt formed from bismuth metal and citric acid, a natural fermentation-derived fruit acid, used to buffer, chelate…

 Dihydroxyacetone 100% natural origin

The active self-tanning ingredient that reacts with skin's surface proteins to produce a temporary bronze colour; made by…

 Epicatechin 100% natural origin

An antioxidant compound naturally found in tea and cocoa, used in skin, hair and oral care. It's extracted…

 Lawsonia Inermis Extract 100% natural origin

A plant extract from the henna shrub, used to condition hair and skin and add a reddish tint.…

 Pyrogallol 100% natural origin

A hair-dye ingredient traditionally made by heating gallic acid, itself extracted from plant tannins in gallnuts, until it…

Structure

2D structure of Acid Red 27

trisodium;3-hydroxy-4-[(4-sulfonatonaphthalen-1-yl)diazenyl]naphthalene-2,7-disulfonate

PubChem CID 13506 ↗

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 Red 27. PubChem CID 13506. National Center for Biotechnology Information. pubchem.ncbi.nlm.nih.gov ↗
  3. 3ACID RED 27. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
  4. 4ACID RED 27. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=ACID%20RED%2027