Substance Information

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REACH Registration data can be found in the new ECHA CHEM database. The old ‘Registered substance factsheets’ will be available on this web site during the transition period but have not been updated since 19 May 2023. More


Substance Infocard


Barium bis[4-[(2-hydroxy-1-naphthyl)azo]-2-methylbenzenesulphonate]

EC / List no.: 227-459-1

CAS no.: 5850-87-3

Mol. Formula: C34H26BaN4O8S2

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Key datasets


Regulatory context

Here you can find all of the regulations and regulatory lists in which this substance appears, according to the data available to ECHA. This substance has been found in the following regulatory activities (directly, or inheriting the regulatory context of a parent substance):

REACH - Registration, Evaluation, Authorisation and Restriction of Chemicals Regulation
  • Substances indicated, in 2009, as being intended to be registered by at least one company in the EEA.
Previous Legislations
  • Substances listed in the EINECS, ELINCS, or NLP inventories.
Cosmetic Products Regulation
  • Cosmetic Products Regulation, Annex IV - Allowed Colorants
    EU. Allowed Colorants: Annex IV, Regulation 1223/2009/EC on Cosmetic Products, as corrected by Corrigendum to Commission Regulation (EU) 2021/850, 17 June 2021

    This list contains coloring agents allowed for use in cosmetic products marketed in the European Union. The list indicates the approved fields for application, including whether or not the colorant is permitted for use in products applied near the eye or on mucous membranes, or in products intended to come in contact with the skin.

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Substance names and other identifiers

Regulatory process names
Barium bis(4-((2-hydroxy-1-naphthyl)azo)-2-methylbenzenesulphonate)
Barium bis[4-[(2-hydroxy-1-naphthyl)azo]-2-methylbenzenesul-phonate]
Cosmetic Products Regulation, Annex IV - Allowed Colorants
Barium bis[4-[(2-hydroxy-1-naphthyl)azo]-2-methylbenzenesulphonate]
EC Inventory
Barium bis[4-[(2-hydroxy-1-naphthyl)azo]-2-methylbenzenesulphonate]
barium bis[4-[(2-hydroxy-1-naphthyl)azo]-2-methylbenzenesulphonate]
Pre-Registration process
Benzenesulfonic acid, 4-((2-hydroxy-1-naphthalenyl)azo)-2-methyl-, barium salt (2:1)
Benzenesulfonic acid, 4-(2-(2-hydroxy-1-naphthalenyl)diazenyl)-2-methyl-, barium salt (2:1)
C.I. 15580
C.I. Pigment Red 51
Pigment Red 51
IUPAC names
barium(2+) bis(4-[(E)-2-(2-hydroxynaphthalen-1-yl)diazen-1-yl]-2-methylbenzene-1-sulfonate)
Other identifiers
EC Inventory, Pre-Registration process, Cosmetic Products Regulation, Annex IV - Allowed Colorants, Other
CAS number