Octamethylcyclotetrasiloxane

CAS 556-67-2[-Si(CH3)2O-]4Chemical Synthesis

Octamethylcyclotetrasiloxane (CAS: 556-67-2), with the formula [-Si(CH3)2O-]4 and a molecular weight of 296.62 g/mol, is a cyclic siloxane. It is a colourless liquid used primarily in chemical synthesis and as a precursor in the production of silicone polymers and materials. Its properties make it valuable in various industrial applications requiring thermally stable and chemically resistant compounds.

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Octamethylcyclotetrasiloxane ([-Si(CH3)2O-]4) — chemical structure, CAS 556-67-2; Chemistry, fine chemical supplied by Tech Serve Solutions

Chemical SynthesisOrganometallic ReagentsOrganosiliconSiloxanes

01 /Applications

Chemical Synthesis

Octamethylcyclotetrasiloxane serves as a key building block in organic and organometallic synthesis. It is frequently employed as a starting material for ring-opening polymerization to produce polydimethylsiloxanes.

Silicone Polymer Production

This compound is a fundamental monomer for manufacturing a wide range of silicone polymers, including elastomers, resins, and fluids. These polymers find applications in sealants, adhesives, coatings, and lubricants.

Intermediate for Materials Science

It acts as an intermediate in the development of advanced materials, offering unique properties such as high thermal stability, electrical insulation, and low surface tension for specialised applications.

02 /Properties

Molecular weight	296.62
Linear formula	[-Si(CH3)2O-]4
Assay	98%
Grade	purum
Form	liquid
Boiling point	175-176 °C(lit.)
Density	0.956 g/mL at 25 °C(lit.)
Melting point	17-18 °C(lit.)
Refractive index	n20/D 1.396(lit.)
Vapour density	1 (vs air)

03 /Safety & handling

GHS hazard pictogram: Flammable (GHS02) — Flammable

GHS hazard pictogram: Health hazard (GHS08) — Health hazard

Warning

Hazard statements

H226Flammable liquid and vapour
H361F
H413May cause long-lasting harmful effects to aquatic life

Precautionary statements

P281Use personal protective equipment as required

Protective equipment	Eyeshields, full-face respirator (US), Gloves, multi-purpose combination respirator cartridge (US), type ABEK (EN14387) respirator filter
Flash point	55 °C / 131 °F
Transport (UN / ADR)	UN 1993C 3 / PGIII
Water hazard class (WGK, DE)	3
Hazard codes (EU)	Xn
Risk statements (R)	10-53-62
Safety statements (S)	36/37-46-51-61

Hazard information is provided for guidance. Always consult the product Safety Data Sheet (SDS), available on request, before handling.

04 /Identifiers & registry

CAS number

556-67-2

MDL number

MFCD00003269

PubChem substance

24886726

Beilstein registry

1787074

05 /Quality & supply

Documentation

Every batch ships with a Certificate of Analysis covering assay, identity and purity; the grade is confirmed against your enquiry. Safety Data Sheets and technical data sheets are available on request.

Supply & logistics

Samples for technical evaluation; bulk MOQ by grade and packaging. In-stock material ships in 7–10 working days, worldwide, with full export documentation.

06 /Frequently asked questions

What is Octamethylcyclotetrasiloxane primarily used for?

Octamethylcyclotetrasiloxane is primarily used in chemical synthesis and as a monomer for the production of silicone polymers and materials.

What is the CAS number and chemical formula for Octamethylcyclotetrasiloxane?

The CAS number for Octamethylcyclotetrasiloxane is 556-67-2, and its chemical formula is [-Si(CH3)2O-]4.

What grade and purity does Tech Serve Solutions supply?

Tech Serve Solutions supplies Octamethylcyclotetrasiloxane at a purum grade with an assay of 98%. We do not represent this product as USP, BP, or EP grade.

How should Octamethylcyclotetrasiloxane be handled safely?

Octamethylcyclotetrasiloxane is a flammable liquid (H226) and may cause long-term harmful effects to aquatic life (H413). It is also suspected of damaging fertility (H361f). Handle with appropriate personal protective equipment, including eyeshields, gloves, and suitable respiratory protection. Store away from ignition sources in a well-ventilated area.

How is Octamethylcyclotetrasiloxane packed and shipped?

Octamethylcyclotetrasiloxane is typically supplied as a liquid and is packaged according to safety regulations for flammable liquids. TSS exports this chemical globally, adhering to international shipping standards.