Tetraethyl orthosilicate

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.

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
UNII
  • InChI=1S/C8H20O4Si/c1-5-9-13(10-6-2,11-7-3)12-8-4/h5-8H2,1-4H3 Y
    Key: BOTDANWDWHJENH-UHFFFAOYSA-N Y
  • 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
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
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)
  • 1000 ppm (rat, 4 hr)
  • 700 ppm (guinea pig, 6 hr)
  • 1740 ppm (guinea pig, 15 min)
  • 1170 ppm (guinea pig, 2 hr)
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 100 ppm (850 mg/m3)
REL (Recommended)
TWA 10 ppm (85 mg/m3)
IDLH (Immediate danger)
700 ppm
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

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.

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