Silicone Fluids & Oils Available — Bulk Only

Octamethylcyclotetrasiloxane (Cyclotetrasiloxane, D4)

D4
CAS 556-67-2 · Formula C8H24O4Si4 · MW 296.61 g/mol

A cyclic siloxane used as a monomer for silicone polymers and as a volatile carrier fluid. Industry references record use in the preparation of methyl silicone oils and as a solvent, diluent, and cosmetic emollient and conditioning fluid.

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UN Number
UN 1993
Hazard Class
Class 3
HS Code
2931.90
At a Glance
Material Family
Silicone Fluids & Oils
Record Type
Pure compound
Primary Role
Solvency · Emolliency
Functional Roles
CYCLOTETRASILOXANE
HAIR CONDITIONINGSKIN CONDITIONING - EMOLLIENTSOLVENT
Applications & Use Cases
  • Silicone intermediate: Monomer for manufacture of methyl silicone oils and polymers
  • Carrier solvent: Volatile vehicle and diluent in formulations
  • Emollient: Smooth feel and spreadability in personal care
  • Hair conditioning: Conditioning and antistatic fluid in hair care
Physical Properties
Melting Point
17.5 °C
Boiling Point
175 °C
Density
Specific gravity: 0.9558
Solubility
In water, 0.056 mg/L at 23 °C
Vapor Pressure
1.05
Flash Point
55 °C (55 °C)
Safety & Handling
Full SDS available on request

A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.

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DOT / UN Transport Classification
DOT hazard class 3 placard
UN / DOT NumberUN 1993
Hazard Class / DivisionClass 3
Proper Shipping NameFlammable liquids, n.o.s.

Transport classification per the UN Model Regulations / 49 CFR 172.101 Hazardous Materials Table. Confirm against the grade-specific SDS (Section 14) before shipping.

HS / Tariff Classification
Harmonized System (HS) Code — 6-digit international heading
2931 . 90
Chapter 29
Organic chemicals
Heading 29.31
Internationally harmonized (WCO HS)
Subheading 2931.90
6-digit international code — national tariff line adds further digits
Chemical Identity
CAS Number
556-67-2
Molecular Formula
C8H24O4Si4
Molecular Weight
296.61 g/mol
IUPAC Name
2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane
INCI Name
CYCLOTETRASILOXANE
PubChem CID
InChI Key
HMMGMWAXVFQUOA-UHFFFAOYSA-N
Synonyms & Trade Names
OCTAMETHYLCYCLOTETRASILOXANE Cyclotetrasiloxane, octamethyl- 2,2,4,4,6,6,8,8-Octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane Oktamethylcyklotetrasiloxan OMCTS Cyclic dimethylsiloxane tetramer Cyclomethicone 4 Silicone SF 1173 KF 994 SF 1173 UC 7207 VS 7207 NUC silicone VS 7207 Union carbide 7207
Full Description

Octamethylcyclotetrasiloxane (D4, CAS 556-67-2), a volatile cyclic dimethylsiloxane. Industry references record use in the preparation of methyl silicone oils and as a solvent, diluent, and cosmetic emollient and conditioning fluid. Supplied as a clear, low-viscosity liquid.

Frequently Asked Questions

What is cyclotetrasiloxane (D4) used for?

Octamethylcyclotetrasiloxane (D4, CAS 556-67-2) is a volatile cyclic dimethylsiloxane used primarily as a monomer in the manufacture of methyl silicone oils and polymers. It also serves as a volatile carrier solvent and diluent, an emollient for smooth feel and spreadability, and a conditioning/antistatic fluid in hair care.

What is cyclotetrasiloxane made from, and what is its CAS number?

D4 is octamethylcyclotetrasiloxane, a four-unit cyclic dimethylsiloxane with formula C8H24O4Si4 and CAS 556-67-2. It is produced from the hydrolysis and cyclization of dimethyldichlorosilane and is itself a key building block for making silicone polymers. Identity and grade are confirmed on the CoA.

Is cyclotetrasiloxane water soluble?

No. D4 is a low-viscosity silicone liquid that is not water soluble; it is miscible with other silicones and nonpolar solvents, which supports its use as a carrier and polymer feedstock. See the product SDS for full solubility and handling data.

What is the difference between D4, D5, and D6 cyclic siloxanes?

They differ in ring size: D4 (cyclotetrasiloxane) has four siloxane units, D5 five, and D6 six. Increasing ring size raises boiling point and lowers volatility, so D4 is the most volatile of the three. D4 is most often used as a polymerization monomer, while D5 and D6 are more common as personal-care carriers.

What is the cost of bulk cyclotetrasiloxane (D4)?

Bulk D4 pricing depends on grade, packaging, order volume, and destination and is quoted per order rather than listed. Submit a bulk RFQ with your quantity and spec and RawSource will return current pricing with CoA and SDS, classified under HS code 2931.90.

Disclaimer. Information on this page — including properties, identifiers, hazard, transport (DOT/UN) and tariff (HS) classifications, and applications — is provided for general reference and is compiled from authoritative public sources (e.g. PubChem/ECHA, 49 CFR 172.101, the Harmonized Tariff Schedule). Values are typical and are not a guaranteed specification; the Certificate of Analysis (CoA) for the lot purchased governs. Products are sold for industrial and professional use only. Nothing here is a medical, health, or efficacy claim or advice. Always consult the current Safety Data Sheet (SDS) before handling, storage, transport or disposal, and confirm regulatory status, classification and suitability for your application and jurisdiction. Hazard, transport and tariff classifications must be verified for your specific shipment. RawSource makes no warranty, express or implied, and assumes no liability for use of this information. Trademarks. Third-party trademarks and brand names are the property of their respective owners; any reference is nominative — used only to identify a comparable product — and does not imply affiliation with, sponsorship by, or endorsement by the trademark owner.