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Description and features

SilQon OMCTS ( Octamethylcyclotetrasiloxane ) is a clear liquid which has C8H24O4Si4 as chemical formula. It is a cyclic organic silicon substance  which can be used as monomer in the production of silicone polymers such as rubber, resins and greases.

Octamethylcyclotetrasiloxane is also known as D4.


Europe and United States: Provided SilQon OMCTS is on stock in our local warehouses our lead time is about one week if delivered in 200 KG steel drums.

Canada, South America, South Africa and other markets can also be served, please contact our sales department for more details.

This product (CAS: 556-67-2) has been registered (FULL substance) under REACH (EC) 1907/2006.

Product Identification

CAS number 556-67-2
EC number 209-136-7
HS code 2931 90 00
EC name Octamethylcyclotetrasiloxane
IUPAC name Octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane


Appearance Colourless clear liquid
Assay ≥ 99.00 %
Refractive index: 1.3968 @ 25ºC


SilQon OMCTS is used as a monomer in the production of silicone polymers and as an intermediate in the production of other organosilicon substances. Further it finds its application in electronics, textiles, personal care products and household care products.


Available packaging: 180 KG steel drums / IBC’s.
Special packaging is available on request.


Store Octamethylcyclotetrasiloxane in a cool, dry and well-ventilated area and in line with legal requirements.


A Material Safety Data Sheets (MSDS) is available for SilQon OMCTS and all other products supplied by Vesta Chemicals BV.

An MSDS describes the hazards of a product and explains how a product can be safely handled, used and stored. Besides it provides important regulatory and emergency response information for the purchased product.

Molecular and structural information

Molecular formula C8H24O4Si4
Molecular weight 296.61 g/mol
Smiles C[Si]1(O[Si](O[Si](O[Si](O1)(C)C)(C)C)(C)C)C
Chemical formula

Physicochemical information

Boiling point175 ºC @ 101 325 Pa
Bulk density 0.95 g/cm3 @ 25 ºC
Flash point 51 ºC @ 101 325 Pa
Log Pow 6.49 @ 25.1 ºC
Solubility in water 0.056 mg/L @ 25 ºC
Vapor pressure 132 Pa @ 25 ºC

Octamethylcyclotetrasiloxane | CAS: 556-67-2. Disclaimer. This information is supplied solely for informational purposes and Vesta Chemicals bv makes no guarantees or warranties, either expressed or implied, with respect to the accuracy and use of this data. All product warranties and guarantees shall be governed by the Standard Terms of Sale. Nothing in this document is legal advice or is a substitute for competent legal advice.