Why does CAS 556-67-2 appear in more than one EU cosmetic annex?

A substance identified by CAS 556-67-2 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts — for example, restricted under Annex III with specific conditions, while also appearing in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

How do I check if my formula contains a substance with CAS 556-67-2?

Use the INCI Checker on CosIng Checker with INCI names, CAS numbers or EC numbers. Paste CAS 556-67-2 to screen it directly, then review every linked annex record and supplier document.

CAS 1 record

CAS 556-67-2

Q: How do I use CAS 556-67-2 for compliance screening?

Cross-reference CAS 556-67-2 against your raw material specification sheets and CoA documents. When it appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met. All annex entries sharing this CAS number are listed on this page.

CAS 556-67-2 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 556-67-2

CAS 556-67-2PubChem CID 11169

Octamethylcyclotetrasiloxane

Octamethylcyclotetrasiloxane is a cyclosiloxane that is the octamethyl derivative of cyclotetrasiloxane. It is an organosilicon compound and a cyclosiloxane. It derives from a hydride of a cyclotetrasiloxane. — ChEBI

IUPAC name: 2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane

Molecular formula: C8H24O4Si4
Molecular weight: 296.61 g/mol
Exact mass: 296.07516538 Da
Topological polar surface area: 36.9 Å²
Hydrogen-bond donors: 0
Hydrogen-bond acceptors: 4
Covalent units: 1
Defined stereocentres: 0

Also known as

Cyclotetrasiloxane, octamethyl-OktamethylcyklotetrasiloxanOMCTSCyclic dimethylsiloxane tetramerCyclomethicone 4NUC silicone VS 7207Union carbide 7207Silicone SF 1173

16 more reported names

KF 994SF 1173UC 7207VS 7207NSC-345674CHEBI:25640RefChem:167770209-136-7Simethicone Impurity 3OktamethylzyklotetrasiloxanDimethylsiloxane Cyclic Tetramer2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetroxatetrasilocaneC8H24O4Si4CAS-556-67-2CCRIS 1327HSDB 6131

Open full PubChem record PubChem annotations 3D structure image

External database identifiers

ChEBI:CHEBI:25640
ChEMBL:CHEMBL1869229
EPA DTXSID:DTXSID7027205
PubMed:36100151
PubMed:28927721
PubMed:27601420
PubMed:25680588
PubMed:22594975
PubMed:22575024
PubMed:22571757
PubMed:22304371
PubMed:22280441
PubMed:22071495
PubMed:21901312
PubMed:21716673

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

Records for CAS 556-67-2

1 total

Annex

Entry

1388

Octamethylcyclotetrasiloxane; D4

209-136-7

CMR

How CAS 556-67-2 is used on this site

CAS 556-67-2 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 556-67-2 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 556-67-2 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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