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Annex II Entry 1353 13/08/2020

1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products

1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products is listed in Annex II as a prohibited substance for cosmetic products placed on the EU market.

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Prohibited substance— Annex II, EU Regulation 1223/2009
Entry: 1353

Chemical identity and properties

PubChem 2D chemical structure for CAS 85-86-9
CAS 85-86-9PubChem CID 62331

1-(p-Phenylazophenylazo)-2-naphthol (Sudan III)

Sudan III is a bis(azo) compound that is 2-naphthol substituted at position 1 by a 4-{[(2-methylphenyl)diazenyl]phenyl}diazenyl group. A fat-soluble dye predominantly used for demonstrating triglycerides in frozen sections, but which may also stain some protein bound lipids in paraffin sections. It has a role as a carcinogenic agent, a fluorochrome and a histological dye. It is a member of azobenzenes, a member of naphthols and a bis(azo) compound. It is functionally related to a 2-naphthol. — ChEBI

IUPAC name
1-[(4-phenyldiazenylphenyl)diazenyl]naphthalen-2-ol
Molecular formula
C22H16N4O
Molecular weight
352.4 g/mol
Exact mass
352.13241115 Da
XLogP3
5.9
Topological polar surface area
69.7 Ų
Hydrogen-bond donors
1
Hydrogen-bond acceptors
5
Covalent units
1
Defined stereocentres
0

Also known as

Sudan IIISolvent red 23C.I. Solvent Red 23Toney RedFettponceau GCerasin RedFat Scarlet LBFettscharlach
16 more reported names
CerasinrotFettrotSudan Red IIIRouge cerasineStearix ScarletPyronalrot BSudan P IIIFettscharlach LBOrganol Red BSSoudan IIICerotinscharlach RSomalia Red IIIMotirot 2RSudan Red BKFat Red RFat Red HRR
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Record details

Chemical name

1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products

Chemical / IUPAC name

1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products

Regulatory information

Regulation

(EC) 2013/344

See every entry this act set

SCCS opinions

Identified ingredients

Key data

CAS
85-86-9
EC
201-638-4
Annex
II
Entry number
1353

Inventory links for 1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products

Inventory Restriction reference
Ref 32744

CI 26100

CAS: 85-86-9
EC: 201-638-4
Inventory Restriction reference
Ref 38153

SOLVENT RED 23

CAS: 85-86-9
EC: 201-638-4

Direct matches are limited for this record, so nearby entries from Annex II are shown as well.

What Annex II means for 1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products

1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products is listed as a prohibited substance under Annex II of EU Cosmetics Regulation 1223/2009 and must not be intentionally added. Article 17 separately addresses unintended small quantities that are technically unavoidable under good manufacturing practice and compatible with the Article 3 safety requirement.

Formulators must screen their ingredients and raw materials to ensure none contain this substance. Suppliers should provide documentation confirming absence when requested.

This record is linked to 2 CosIng inventory ingredients for name and identifier cross-reference. The page also surfaces 12 related annex records with overlapping identifiers, annex logic or naming patterns.

Compliance checklist

  • Verify this substance is absent from all raw materials and finished formulations.
  • Request absence confirmation or CoA from raw material suppliers.
  • Document the screening result in the Product Information File (PIF).

Frequently asked questions

Yes. 1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products is listed in Annex II of EU Cosmetics Regulation 1223/2009 and is prohibited as an intentionally added cosmetic ingredient. Article 17 provides a narrow exception for unintended small quantities that are technically unavoidable under good manufacturing practice, provided the product remains safe under Article 3.

CAS 85-86-9 is the unique numerical identifier assigned to 1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products by the Chemical Abstracts Service. In cosmetic compliance work, the CAS number is used to cross-reference the substance across regulatory databases, raw material specifications and safety assessment reports. Multiple EU annex entries may share the same CAS number if the same substance appears under different conditions or in different annexes.

Use the INCI Checker tool on this site to paste your full ingredient list (INCI) and scan it against all Annex II–VI entries. The tool highlights any ingredients that match restricted, prohibited or allergen-flagged records. This is useful for rapid compliance screening of finished product formulas or raw material declarations.
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Source note for Annex II record 1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products

This page summarizes one Annex II record for 1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products from public European Commission cosmetic materials and adds linked inventory or identifier matches when available.

Use this record page to review Annex II conditions for 1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair dye products, but confirm any final regulatory decision against the current official annex wording and source files.

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