Octamethylcyclotetrasiloxane

  • Cyclic dimethylsiloxane tetramer
  • Tetracyclomethicone
  • Dow Corning 344
  • Silbione V 2
  • Union Carbide 7207
  • Volasil 244
Formula
C8H24O4Si4
Structure
Description
Oily liquid.
Uses
Prepn of methyl silicon oils.

Registry Numbers and Inventories.
CAS
556-67-2
EC (EINECS/ELINCS)
209-136-7
EC Index Number
014-018-00-1
EC Class
Toxic for reproduction Category 3; Dangerous for the Environment
R 53 61
S 36/37 46 51 61
RTECS
GZ4397000
RTECS class
Reproductive Effector; Primary Irritant
UN (DOT)
1993
Merck
12,6843
Beilstein/Gmelin
1787074
Beilstein Reference
4-04-00-04125
Canada DSL/NDSL
DSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed
Korea ECL
Listed

Properties.
Formula
C8H24O4Si4
Formula mass
296.62
Melting point, °C
18
Boiling point, °C
175
Vapor pressure, mmHg
1
Vapor density (air=1)
10.23
Critical temperature
313
Critical pressure
13.03
Density
0.95 g/cm3
Solubility in water
Insoluble
Viscosity
2.24 cp (25 C)
Refractive index
1.3965 (20 C)
Heat of combustion
-8141 kJ/mol

Hazards and Protection.
Storage
Keep in a cool, dry, dark location in a tightly sealed container or cylinder. Keep away from incompatible materials, ignition sources and untrained individuals. Secure and label area. Protect containers/cylinders from physical damage.
Handling
All chemicals should be considered hazardous. Avoid direct physical contact. Use appropriate, approved safety equipment. Untrained individuals should not handle this chemical or its container. Handling should occur in a chemical fume hood.
Protection
Wear appropriate protective gloves, clothing and goggles.
Respirators
Wear positive pressure self-contained breathing apparatus (SCBA).
Small spills/leaks
Make no contact with the spilled material. ELIMINATE all ignition sources and ground all equipment. Stop leak if you can do it without risk. A vapor suppressing foam may be used to reduce vapors. Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. Use clean non-sparking tools to collect absorbed material.
Stability
No data.

Fire.
Flash Point,°C
57
Autoignition, °C
400
Upper exp. limit, %
7.4
Lower exp. limit, %
0.8
Fire fighting
Use of water spray when fighting fire may be inefficient. Small Fires: Dry chemical, carbon dioxide, water spray or alcohol-resistant foam. Large Fires: Water spray, fog or alcohol-resistant foam. Use water spray or fog; do not use straight streams.
Fire potential
HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
Hazards
Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers.
Combustion products
Fire may produce irritating, corrosive and/or toxic gases.
Health
3
 
Flammability
2
 
 
Reactivity
1
 

Health.
Exposure effects
The toxological properties of this substance have not been fully investigated.
   Inhalation
Silicone injection has been associated with the development of fatal pulmonary edema, pneumonitis, pleural effusion, ards and dyspnea.
   Skin
Hypopigmentation and peau d'orange skin changes have been reported after silicone injection or implantation.
   Eyes
See Skin.

First aid
 
   Ingestion
Seek medical assistance.
   Inhalation
Inhalation hazard is low due to the low vapor pressure of most silicone fluids. Treatment is symptomatic and supportive.
   Skin
Remove and isolate contaminated clothing and shoes. Wash skin with soap and water. Flush with running water for at least 20 minutes
   Eyes
Flush with running water for at least 20 minutes.

Transport.
UN number
1993
Response guide
Hazard class
3
Packing Group
I; II; III
 
HS Code
2931 00 95