What Is Hexamethyldisiloxane?

2026-08-17

Hexamethyldisiloxane, abbreviated as HMDSO (CAS 107-46-0), is a colourless, transparent liquid with a density of approximately 0.8 g/cm³, a boiling point of approximately 100°C, a melting point of -59°C, and a flash point of approximately -2°C. It is insoluble in water but soluble in most organic solvents. Industrially, it is used as a capping agent, cleaning agent, and release agent; it is employed in the manufacture of silicone oil, silicone rubber, and other silicone products; it also serves as a water-repellent agent for fabric surface treatment and moisture protection of components; and it can be used as a stationary phase in gas chromatography. It is classified as a flammable liquid with a hazard category of 3 and must be stored in a cool, dry, and well-ventilated environment, away from sources of ignition and heat, and separated from oxidising agents.

What Are the Properties of Hexamethyldisiloxane?

Melting point	−59 °C (lit.)
Boiling point	101°C (lit.)
Density	0.764 g/mL at 20 °C (lit.)
vapor density	>1 (vs air)
vapor pressure	20 hPa (20 °C)
refractive index	n20/D 1.377(lit.)
Flash point	33 °F
storage temp.	Store below +30°C.
solubility	0.00037 g/l insoluble
Water Solubility	insoluble

Hexamethyldisiloxane Risk and Safety Statements

Symbol(GHS)	GHS02, GHS09
Signal word	Danger
Hazard statements	H410-H225
Precautionary statements	P501-P273-P240-P210-P233-P243-P241-P242-P280-P370+P378-P391-P303+P361+P353-P403+P235
PPE	Eyeshields, Faceshields, Gloves, type ABEK (EN14387) respirator filter
Hazard Codes	F, N, T
Risk Statements	11-50/53-65-51/53-48/23/24/25-36/38-46-45
Safety Statements	16-61-62-45-26-53
WGK Germany	3
Hazard Class	3
PackingGroup	II
Storage Class	3 - Flammable liquids

What Is Hexamethyldisiloxane Used for?

Silicone Industry

HMDSO is primarily used as a capping agent (chain terminator) and a key intermediate in the production of silicone products such as silicone oils, silicone rubbers, and silicone resins.

Surface Treatment

HMDSO is used as a water-repellent agent in the surface treatment of textile fabrics and for insulation and moisture protection in radio components.

Chemical Manufacturing

HMDSO is used as a cleaning agent and release agent in organic and pharmaceutical chemical production. Additionally, it can be used as a circulating coolant for instruments and meters, as well as an analytical reagent, insulating material, and moisture-proofing agent.