C8H24O4Si4
296.61 g/mol
cosmetic_ingredientWarning
Cyclotetrasiloxane, octamethyl-
CAS556-67-2EC209-136-7
Category
cosmetic_ingredient
Compound Class
Heterocycle
Primary Use
Cosmetic ingredient and industrial solvent
Octamethylcyclotetrasiloxane is a cyclic organosilicon compound consisting of a four-membered ring of alternating silicon and oxygen atoms, with each silicon bearing two methyl groups. It is primarily used in cosmetics and as an industrial solvent.
cosmetic ingredientindustrial solventpreparation of methyl silicon oils
Content scope: Information here supports chemical identification and industrial supply, research, and manufacturing contexts. It is not a therapeutic claim, medical advice, or drug-use instructions.
Restricted or banned substances
Substances on this list are banned or restricted under the named regulation. This page is a compliance reference — verify your obligations under applicable law.
Relevant lists:EU REACH Restriction List
CAS 556-67-2
Related Compounds
StrongStructure SimilarSimilarity 1.00
Cyclomethicone 5
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Carrier in personal care products
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Biocide preservative in consumer products
ReferenceSame Category
Palmitic acid
CAS57-10-3
cosmetic formulation ingredient
ReferenceSame Category
Sodium glycinate
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cosmetic ingredient
ReferenceSame Category
ZINC LACTATE
CAS6155-68-6
Cosmetic ingredient for zinc supplements
Referencesame scaffold
2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane
CAS2554-06-5
electronic chemical precursor
Safety Reference
Warning
H410Very toxic to aquatic life with long lasting effects
H226Flammable liquid and vapour
H361Suspected of damaging fertility or the unborn child
H413May cause long lasting harmful effects to aquatic life
Customs Tariff Classification
The international HS code for Cyclotetrasiloxane, octamethyl- (CAS 556-67-2) is 2931.90.
HS code (international, 6-digit)
2931.90
EU CN code (8-digit)
2931 90 00
Classification per the EU customs inventory ECICS (2026-07 snapshot, HS 2022). National tariff lines and product form can affect the final classification.
Identifiers
IUPAC Name
2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane
InChIKey
HMMGMWAXVFQUOA-UHFFFAOYSA-N
SMILES
C[Si]1(O[Si](O[Si](O[Si](O1)(C)C)(C)C)(C)C)C
Synonyms (22)
- OMCTS
- Cyclomethicone 4, United States Pharmacopeia (USP)
- Cyclomethicone 4
- NUC silicone VS 7207
- Oktamethylcyklotetrasiloxan
- Oktamethylzyklotetrasiloxan
- Silicone SF 1173
- Simethicone Impurity 3
- Union carbide 7207
- octamethyl-cyclotetrasiloxane