Methyl orthosilicate

  • Tetramethyl orthosilicate
  • Methyl silicate
Formula
C4H12O4Si
Structure
Description
Clear colorless liquid.
Uses
In coating picture screens of television picture tubes.

Registry Numbers and Inventories.
CAS
681-84-5
EC (EINECS/ELINCS)
211-656-4
EC Class
flammable, very toxic, irritant
R 10 23 34 37 41
S 26 28 36/37/39 45
RTECS
VV9800000
RTECS class
Other
UN (DOT)
2606
Beilstein/Gmelin
1699658
Beilstein Reference
4-01-00-01266
Swiss Giftliste 1
G-2533
Canada DSL/NDSL
DSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed
Korea ECL
Listed

Properties.
Formula
C4H12O4Si
Formula mass
152.22
Melting point, °C
-2
Boiling point, °C
121
Vapor pressure, mmHg
18 (25 C)
Vapor density (air=1)
5.3
Saturation Concentration
16000 ppm (1.6%) at 25 C (calculated)
Density
1.02 g/cm3 (20 C)
Solubility in water
Insoluble
Viscosity
0.64 cp (20 C)
Surface tension
24.98 g/s2 (18 C)
Refractive index
1.3683 (20 C)
Partition coefficient, pKow
2.97
Heat of vaporization
37.1 kJ/mol
Heat of combustion
-2906 kJ/mol

Hazards and Protection.
Storage
Store in closed container in a dry location. Keep away from sources of ignition and heat.
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
Keep sparks, flames, and other sources of ignition away. Keep material out of water sources and sewers. Build dikes to contain flow as necessary. Attempt to stop leak if without undue personnel hazard. Use water spray to knock-down vapors. Disperse vapors using fans or blowers. Land spill: Dike surface flow using soil, sand bags, foamed polyurethane, or foamed concrete. Absorb bulk liquid with fly ash, cement powder, or commercial sorbents. Water spill: Use natural barriers or oil spill control booms to limit spill travel. Remove trapped material with suction hoses.
Stability
No data.
Incompatibilities
Oxidizers, hexafluorides of rhenium, molybdenum & tungsten.
Decomposition
Carbon monoxide, hydrogen cyanide and oxides of nitrogen.

Fire.
Flash Point,°C
26
Autoignition, °C
240
Fire fighting
Do not extinguish fire unless flow can be stopped. Use water in flooding quantities as fog. Solid streams of water may be ineffective. Cool all affected containers with flooding quantities of water. Use foam, dry chemical, or carbon dioxide. Keep run-off water out of sewers and water sources.
Fire potential
HIGHLY FLAMMABLE.
Hazards
Vapors form explosive mixtures with air: indoors, outdoors, and sewers explosion hazards. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapors may travel to source of ignition and flash back. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.
Combustion products
Fire will produce irritating, corrosive and/or toxic gases.
Health
3
 
Flammability
3
 
 
Reactivity
1
 

Health.
Exposure limit(s)
TLV: 1 ppm; 6 mg/m3 (ACGIH 1997). NIOSH REL: TWA 1 ppm (6 mg/m3)
Poison_Class
2
Exposure effects
   Ingestion
See Inhalation.
   Inhalation
Corrosive. Causes burns. Highly destructive to skin, eyes, mucous membranes and upper respiratory tract. Ingestion or inhalation could prove fatal. Spasms, inflammation and edema of the lungs.
   Skin
See Inhalation.
   Eyes
See Inhalation.

First aid
 
   Ingestion
Do not induce vomiting. Give copious amounts of water and seek immediate medical attention.
   Inhalation
Move patient to fresh air. Monitor for respiratory distress. If cough or difficulty breathing develops, evaluate for respiratory tract irritation, bronchitis, or pneumonitis. Administer oxygen and assist ventilation as required. Treat bronchospasm with beta2 agonist and corticosteroid aerosols.
   Skin
Remove contaminated clothing and wash exposed area thoroughly with soap and water. A physician should examine the area if irritation or pain persists.
   Eyes
Irrigate exposed eyes with copious amounts of tepid water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist, the patient should be seen in a health care facility.

Transport.
UN number
2606
Response guide
Hazard class
6.1
PRTC
T
Packing Group
I
 
HS Code
2920 90 85
 
Std. Transport #
4921255 4907452