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CAS 1 record

CAS 573-58-0

CAS 573-58-0 matches 1 EU annex record across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 573-58-0
CAS 573-58-0PubChem CID 11313

Congo red

Congo Red is an indicator dye that is blue-violet at pH 3.0 and red at pH 5.0. It contains a 3,3'-(biphenyl-4,4'-diyldidiazene-2,1-diyl)bis(4-aminonaphthalene-1-sulfonate). It is functionally related to a 3,3'-(biphenyl-4,4'-diyldidiazene-2,1-diyl)bis(4-aminonaphthalene-1-sulfonic acid). — ChEBI

IUPAC name
disodium;4-amino-3-[[4-[4-[(1-amino-4-sulfonatonaphthalen-2-yl)diazenyl]phenyl]phenyl]diazenyl]naphthalene-1-sulfonate
Molecular formula
C32H22N6Na2O6S2
Molecular weight
696.7 g/mol
Exact mass
696.08376335 Da
Topological polar surface area
233.0 Ų
Hydrogen-bond donors
2
Hydrogen-bond acceptors
12
Covalent units
3
Defined stereocentres
0

Also known as

DIRECT RED 28C.I. Direct Red 28Congazone sodiumMitsui Congo RedBenzo Congo RedCotton Red LHaemomedicalHaemonorm
16 more reported names
HemorrhagylHispamin Congo 4BSolucongoBrasilamina congo 4BSugai Congo RedAtul Congo RedVondacel Red CLKayaku Congo RedDirect Red KAzocard Red CongoCongo Red HCongo Red LCongo Red MCongo Red NCongo Red RCongo Red W
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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.

Records for CAS 573-58-0

1 total

How CAS 573-58-0 is used on this site

CAS 573-58-0 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 1 EU annex record shares this identifier, which helps you cross-check whether the same substance appears under one regulatory context or several.

Use this page when a supplier specification, SDS or raw-material dossier gives you CAS 573-58-0 and you need to see every linked Annex II–VI record in one place. The entry cards above are the quickest route to concentration limits, warnings, annex placement and product-type conditions.

Frequently asked questions

A substance identified by CAS 573-58-0 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts. For example, a substance might be restricted under Annex III with specific conditions, and the same CAS might also appear in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

Cross-reference the CAS number against your raw material specification sheets and CoA documents. When a CAS appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met in your formulation. All annex entries sharing this CAS number are listed above.

A CAS number is assigned by the Chemical Abstracts Service (USA) and is globally recognised. An EC number is a European Commission identifier from inventories such as EINECS, ELINCS or the NLP list. Both identifiers may appear in EU cosmetic annex entries. Some substances have both, some have only one, and some older entries may have neither.

The INCI Checker accepts ingredient names, CAS numbers and EC numbers. Check this CAS number directly, then verify the result against supplier specification sheets and every linked annex condition.
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