Tetraethyl orthosilicate

Not to be confused with Tetramethyl orthosilicate.
Tetraethyl orthosilicate
Names
IUPAC name
Tetraethyl orthosilicate
Other names
tetraethoxysilane; ethyl silicate, tetra-; silicic acid tetraethyl ester; silicon(IV) ethoxide; TEOS; tetraethyl silicate (ortho-)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.000.986 Edit this at Wikidata
UNII
  • InChI=1S/C8H20O4Si/c1-5-9-13(10-6-2,11-7-3)12-8-4/h5-8H2,1-4H3 checkY
    Key: BOTDANWDWHJENH-UHFFFAOYSA-N checkY
  • InChI=1/C8H20O4Si/c1-5-9-13(10-6-2,11-7-3)12-8-4/h5-8H2,1-4H3
    Key: BOTDANWDWHJENH-UHFFFAOYAS
  • CCO[Si](OCC)(OCC)OCC
Properties
SiC8H20O4
Molar mass 208.33 g⋅mol−1
Appearance Colourless liquid
Odor Sharp, alcohol-like[1]
Density 0.933 g/mL at 20 °C
Melting point −77 °C (−107 °F; 196 K)
Boiling point 168 to 169 °C (334 to 336 °F; 441 to 442 K)
Reacts with water, soluble in ethanol, and 2-propanol
Vapor pressure 1 mmHg[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Flammable, harmful by inhalation
Flash point 45 °C (113 °F; 318 K)
Lethal dose or concentration (LD, LC):
6270 mg/kg (rat, oral)[2]
  • 1000 ppm (rat, 4 hr)
  • 700 ppm (guinea pig, 6 hr)
  • 1740 ppm (guinea pig, 15 min)
  • 1170 ppm (guinea pig, 2 hr)[2]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 100 ppm (850 mg/m3)[1]
REL (Recommended)
 TWA 10 ppm (85 mg/m3)[1]
IDLH (Immediate danger)
 700 ppm[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Tetraethyl orthosilicate, formally named tetraethoxysilane (TEOS), ethyl silicate is the organic chemical compound with the formula Si(OC2H5)4. TEOS is a colorless liquid. It degrades in water. TEOS is the ethyl ester of orthosilicic acid, Si(OH)4. It is the most prevalent alkoxide of silicon.

TEOS is a tetrahedral molecule. Like its many analogues, it is prepared by alcoholysis of silicon tetrachloride:

SiCl4 + 4 EtOH → Si(OEt)4 + 4 HCl

where Et is the ethyl group, C2H5, and thus EtOH is ethanol.

  1. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0282". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ a b "Ethyl silicate". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).