SOLVENT RED 23
1-(4-(Phenylazo)phenylazo)-2-naphthol (CI 26100)
SOLVENT RED 23 is linked to 2 EU annex records on this page. Inventory note: II/1353 (Solvent Red 23; CI 26100: when used as a substance in hair dye products).
Regulatory evidence by market
This matrix separates verified ingredient rules from sources that are mapped but not yet imported. No imported rule does not mean the ingredient is permitted.
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| Market | Evidence status | Records | Source language |
|---|---|---|---|
| European Union | Evidence linked Prohibited entry found Open this evidence | 2 | English and EU languages |
| Great Britain | Source mapped Official source mapped; ingredient rule not imported | 0 | English |
| Canada | Evidence linked Restricted Open this evidence | 1 | English and French |
| New Zealand | Source mapped Official source mapped; ingredient rule not imported | 0 | English |
| ASEAN | Source mapped Official source mapped; ingredient rule not imported | 0 | English and national languages |
| China | Source mapped Official source mapped; ingredient rule not imported | 0 | Chinese with selected English material |
| Japan | Source mapped Official source mapped; ingredient rule not imported | 0 | Japanese; official English translation available |
| South Korea | Source mapped Official source mapped; ingredient rule not imported | 0 | Korean with some English names |
| United States | Source mapped Official source mapped; ingredient rule not imported | 0 | English |
| Australia | Source mapped Official source mapped; ingredient rule not imported | 0 | English |
| Brazil | Source mapped Official source mapped; ingredient rule not imported | 0 | Portuguese with INCI crosswalks |
| India | Source mapped Official source mapped; ingredient rule not imported | 0 | English and Hindi |
| Saudi Arabia | Source mapped Official source mapped; ingredient rule not imported | 0 | Arabic and English |
Chemical identity and properties
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
16 more reported names
External database identifiers
- ChEBI:CHEBI:82535
- ChEMBL:CHEMBL2001927
- EPA DTXSID:DTXSID3041742
- PubMed:39703340
- PubMed:37813177
- PubMed:22287322
- PubMed:20308224
- PubMed:18418879
- PubMed:17598027
- PubMed:15822858
- PubMed:15788368
- PubMed:15585952
- PubMed:1282215
Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.
Inventory details for SOLVENT RED 23
INCI name
SOLVENT RED 23
Description
1-(4-(Phenylazo)phenylazo)-2-naphthol (CI 26100)
Record provenance
- Inventory reference
- 38153
- Imported identity
- SOLVENT RED 23
- Source update
- 13/08/2020
Annex records for SOLVENT RED 23
1-((4-Phenylazo)phenylazo)-2-naphthol (Solvent Red 23; CI 26100) when used as a substance in hair d…
Key data
- HAIR DYEING
- Imparting color to hair. Hair dyeing preparations may be temporary, semi-permanent, or permanent, depending on the length of time the colorant remains on the hair.
Official EU ingredient-name evidence
The ingredient name exactly matches the official 2025 EU glossary of common ingredient names.
The markets do not agree about this substance: it is prohibited in some and permitted under conditions in others, across the 2 markets that hold a rule for it.
- prohibited
- European Union
- restricted
- Canada
Related inventory evidence
Records sharing a CAS or EC identity
Ingredients with overlapping formulation functions
Additional official and scientific sources
11 external databases to check this identity in
Each link searches that source for this identity. What each source is, and its legal weight
How SOLVENT RED 23 appears in the CosIng inventory
The CosIng inventory lists SOLVENT RED 23 as a cosmetic ingredient and this page links it to 2 annex records. The inventory entry captures names and identifiers, while the annex records show where the substance is prohibited, restricted or positively listed in EU cosmetics law.
SOLVENT RED 23 is also tagged with 1 cosmetic function in the official data. Function labels describe intended use, but they do not replace regulatory review of linked annex records before formulation or labelling work.
Frequently asked questions
Source note for SOLVENT RED 23
This page combines the CosIng inventory entry for SOLVENT RED 23 with 2 linked Annex II–VI records from the local dataset built from public European Commission cosmetic ingredient materials.
Use this inventory page to research SOLVENT RED 23 and compare linked records, but verify restrictions and legal status against the current official source text and law before making regulatory decisions.
Tools & next steps
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