Hexamethylcyclotrisiloxane

  • Cyclotrisiloxane, hexamethyl
  • Dimethylsiloxane cyclic trimer
  • Hexamethyltrisiloxane
  • LS 8120
  • SDK 10
Formula
C6H18O3Si3
Structure
Description
Colorless to white crystals.

Registry Numbers and Inventories.
CAS
541-05-9
EC (EINECS/ELINCS)
208-765-4
S 16 22 24/25
UN (DOT)
1325
Beilstein/Gmelin
5676485
Canada DSL/NDSL
DSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed
Korea ECL
Listed

Properties.
Formula
C6H18O3Si3
Formula mass
222.46
Melting point, °C
64.5
Boiling point, °C
134
Vapor pressure, mmHg
4.2 (24 C)
Vapor density (air=1)
8.0
Density
1.12 g/cm3 (20C)
Solubility in water
May decompose.
Viscosity
0.504 cp (65 C)
Partition coefficient, pKow
4.47
Heat of fusion
16.6 kJ/mol
Heat of vaporization
39.8 kJ/mol
Heat of combustion
-5891 kJ/mol

Hazards and Protection.
Storage
Keep away from sources of ignition. Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances. Keep away from water. Store protected from moisture.
Handling
Wash thoroughly after handling. Remove contaminated clothing and wash before reuse. Use with adequate ventilation. Ground and bond containers when transferring material. Avoid contact with eyes, skin, and clothing. Empty containers retain product residue, (liquid and/or vapor), and can be dangerous. Avoid contact with heat, sparks and flame. Avoid ingestion and inhalation. Do not allow contact with water. Do not pressurize, cut, weld, braze, solder, drill, grind, or expose empty containers to heat, sparks or open flames. Keep from contact with moist air and steam.
Protection
Eyes: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA's eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166. Skin: Wear appropriate protective gloves to prevent skin exposure. Clothing: Wear appropriate protective clothing to prevent skin exposure.
Respirators
A respiratory protection program that meets OSHA's 29 CFR 1910.134 and ANSI Z88.2 requirements or European Standard EN 149 must be followed whenever workplace conditions warrant a respirator's use.
Small spills/leaks
Vacuum or sweep up material and place into a suitable disposal container. Clean up spills immediately, using the appropriate protective equipment. Avoid generating dusty conditions. Remove all sources of ignition. Use a spark-proof tool. Provide ventilation. Do not get water inside containers.
Stability
Stable under normal temperatures and pressures.
Incompatibilities
Moisture.
Decomposition
Carbon monoxide, irritating and toxic fumes and gases, carbon dioxide, silicon oxide.

Fire.
Flash Point,°C
32
Lower exp. limit, %
1.1
Fire fighting
Wear a self-contained breathing apparatus in pressure-demand, MSHA/NIOSH (approved or equivalent), and full protective gear. During a fire, irritating and highly toxic gases may be generated by thermal decomposition or combustion. Will burn if involved in a fire. Use water spray to keep fire-exposed containers cool. Containers may explode in the heat of a fire. Extinguishing media: For small fires, use dry chemical, carbon dioxide, water spray or alcohol-resistant foam. For large fires, use water spray, fog, or alcohol-resistant foam. Do NOT use water directly on fire. Use water spray to cool fire-exposed containers. Do NOT get water inside containers.
Fire potential
Flammable/combustible material. May be ignited by friction, heat, sparks or flames.
Hazards
Water Reactive. Material will react with water and may release a flammable and/or toxic gas. Do NOT use water directly on fire.
Combustion products
Fire may produce irritating and/or toxic gases.
Health
1
 
Flammability
2
 
 
Reactivity
0
 

Health.
Exposure effects
Effects may be delayed.
   Ingestion
May cause gastrointestinal irritation with nausea, vomiting and diarrhea. The toxicological properties of this substance have not been fully investigated. Ingestion of large amounts may cause CNS depression.
   Inhalation
The toxicological properties of this substance have not been fully investigated. Aspiration may lead to pulmonary edema. Vapors may cause dizziness or suffocation. May cause burning sensation in the chest.
   Skin
May cause irritation and dermatitis. May cause cyanosis of the extremities.
   Eyes
May cause eye irritation. May cause chemical conjunctivitis and corneal damage.

First aid
 
   Ingestion
Never give anything by mouth to an unconscious person. Get medical aid. Do NOT induce vomiting. If conscious and alert, rinse mouth and drink 2-4 cupfuls of milk or water.
   Inhalation
Remove from exposure to fresh air immediately. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical aid. DO NOT use mouth-to-mouth respiration.
   Skin
Get medical aid. Flush skin with plenty of soap and water for at least 15 minutes while removing contaminated clothing and shoes. Wash clothing before reuse.
   Eyes
Flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Get medical aid.

Transport.
UN number
1325
Response guide
Hazard class
4.1
Packing Group
II; III