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Annex II Entry 1270 21/10/2010

2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, when used as a substance in hair dye products

2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, 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: 1270

Chemical identity and properties

PubChem 2D chemical structure for CAS 25188-41-4
CAS 25188-41-4PubChem CID 75784

7,7'-(Carbonyldiimino)bis(4-hydroxy-3-(2-(2-sulfo-4-(2-(4-sulfophenyl)diazenyl)phenyl)diazenyl)-2-naphthalenesulfonic acid)

Sirius red F3B (acid form) is a naphthalenesulfonic acid that is the free acid form of the dye Sirius red F3B. The hexasodium salt is a histological dye used principally in staining methods for collagen and amyloid. It has a role as a fluorochrome and a histological dye. It is a member of azobenzenes, a member of naphthols, a naphthalenesulfonic acid and a member of ureas. It is a conjugate acid of a Sirius red F3B(6-). — ChEBI

IUPAC name
4-hydroxy-7-[[5-hydroxy-7-sulfo-6-[[2-sulfo-4-[(4-sulfophenyl)diazenyl]phenyl]diazenyl]naphthalen-2-yl]carbamoylamino]-3-[[2-sulfo-4-[(4-sulfophenyl)diazenyl]phenyl]diazenyl]naphthalene-2-sulfonic acid
Molecular formula
C45H32N10O21S6
Molecular weight
1241.2 g/mol
Exact mass
1240.0067751 Da
XLogP3
3.9
Topological polar surface area
557.0 Ų
Hydrogen-bond donors
10
Hydrogen-bond acceptors
29
Covalent units
1
Defined stereocentres
0

Also known as

RefChem:1074252direct red 80 free acidSirius red F3B (acid form)29AND524MI2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-((2-sulfo-4-((4-sulfophenyl)azo)phenyl)azo)-7,7'-(Carbonylbis(azanediyl))bis(4-hydroxy-3-((2-sulfo-4-((4-sulfophenyl)diazenyl)phenyl)diazenyl)naphthalene-2-sulfonic acid)7,7'-(Carbonyldiimino)bis(4-hydroxy-3-((2-sulfo-4-((4-sulfophenyl)azo)phenyl) azo)-2-naphthalenesulfonic acid)7,7'-[Carbonylbis(azanediyl)]bis[4-hydroxy-3-({2-sulfo-4-[(4-sulfophenyl)diazenyl]phenyl}diazenyl)naphthalene-2-sulfonic acid]
10 more reported names
J269.409CSirius red F3B free acidUNII-29AND524MIdirect red 80 (acid form)C.I. Direct Red 80 parentCHEBI:88280IUNAENBIEJRAKZ-UHFFFAOYSA-N2-NAPHTHALENESULFONIC ACID, 7,7'-(CARBONYLDIIMINO)BIS(4-HYDROXY-3-(2-(2-SULFO-4-(2-(4-SULFOPHENYL)DIAZENYL)PHENYL)DIAZENYL)-7,7'-(CARBONYLBISIMINO)BIS(4-HYDROXY-3-(4-(4-SULFOPHENYLAZO)-2-SULFOPHENYLAZO)-2-NAPHTHALENESULFONIC ACID)7,7'-(carbonyldiazanediyl)bis[4-hydroxy-3-({2-sulfo-4-[(4-sulfophenyl)diazenyl]phenyl}diazenyl)naphthalene-2-sulfonic acid]
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

PubChem 2D chemical structure for CAS 2610-10-8
CAS 2610-10-8PubChem CID 75783

Sirius Red F3B

Sirius red F3B is an organic sodium salt resulting from the formal condensation of Sirius red F3B (acid form) with six equivalents of sodium hydroxide. A polyazo dye used principally in staining methods for collagen and amyloid. It has a role as a fluorochrome and a histological dye. It contains a Sirius red F3B(6-). — ChEBI

IUPAC name
hexasodium;4-hydroxy-7-[[5-hydroxy-7-sulfonato-6-[[2-sulfonato-4-[(4-sulfonatophenyl)diazenyl]phenyl]diazenyl]naphthalen-2-yl]carbamoylamino]-3-[[2-sulfonato-4-[(4-sulfonatophenyl)diazenyl]phenyl]diazenyl]naphthalene-2-sulfonate
Molecular formula
C45H26N10Na6O21S6
Molecular weight
1373.1 g/mol
Exact mass
1371.8984406 Da
Topological polar surface area
574.0 Ų
Hydrogen-bond donors
4
Hydrogen-bond acceptors
29
Covalent units
7
Defined stereocentres
0

Also known as

CHEBI:88279RefChem:1098571Direct Red 80C.I. Direct Red 80Sirius Red F 3BSirius Red F 3BASirius RedDiazol Light Red 3B
16 more reported names
Durazol Brillant Red BSC.I. Direct Red 80, hexasodium saltCI 357801294D5G72NHexasodium 7,7'-(carbonyldiimino)bis(4-hydroxy-3-((2-sulphonato-4-((4-sulphonatophenyl)azo)phenyl)azo)naphthalene-2-sulphonate)2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-((2-sulfo-4-((4-sulfophenyl)azo)phenyl)azo)-, hexasodium salt7,7'-(Carbonyldiimino)bis[4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-2-naphthalenesulfonic acid hexasodium saltPicrosirius RedFinisol Red BAFenaluz Red 7B2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-(2-(2-sulfo-4-(2-(4-sulfophenyl)diazenyl)phenyl)diazenyl)-, sodium salt (1:6)HexaNa 7,7'-(carbonyldiimino)bis4-OH-3-2-sulphonato-4-(4-sulphonatophenyl)azophenylazonaphthalene-2-sulphonateDicorel Red L 3ASolophenyl Red 3BLFastusol Red L 8BPyrazoline Red BLWN
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Record details

Chemical name

2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, when used as a substance in hair dye products

Regulatory information

Regulation

(EC) 2009/1223

See every entry this act set

SCCS opinions

Identified ingredients

Key data

CAS
2610-10-8 / 25188-41-4
EC
220-027-3
Annex
II
Entry number
1270

Inventory links for 2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, when used as a substance in hair dye products

Inventory Restriction reference
Ref 33567

DIRECT RED 80

CAS: 2610-10-8
EC: 220-027-3
Inventory Identified ingredient
Ref 33568

DIRECT RED 81

CAS: 2610-11-9
EC: 220-028-9

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

What Annex II means for 2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, when used as a substance in hair dye products

2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, 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. 2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, 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 2610-10-8 / 25188-41-4 is the unique numerical identifier assigned to 2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, 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 2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, when used as a substance in hair dye products

This page summarizes one Annex II record for 2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, 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 2-Naphthalenesulfonic acid, 7,7'-(carbonyldiimino)bis(4-hydroxy-3-[[2-sulfo-4-[(4-sulfophenyl)azo]phenyl]azo]-, and its salts, 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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