Tetraethyl 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
CAS Number	78-10-4 ;
3D model (JSmol)	Interactive image;
ChemSpider	6270 ;
ECHA InfoCard	100.000.986
PubChem CID	6517;
UNII	42064KRE49 ;
CompTox Dashboard (EPA)	DTXSID6026450 ;
	InChI InChI=1S/C8H20O4Si/c1-5-9-13(10-6-2,11-7-3)12-8-4/h5-8H2,1-4H3 Key: BOTDANWDWHJENH-UHFFFAOYSA-N ; InChI=1/C8H20O4Si/c1-5-9-13(10-6-2,11-7-3)12-8-4/h5-8H2,1-4H3 Key: BOTDANWDWHJENH-UHFFFAOYAS;
	SMILES CCO[Si](OCC)(OCC)OCC;
Properties
Chemical formula	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)
Solubility in water	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):
LD50 (median dose)	6270 mg/kg (rat, oral)
LCLo (lowest published)	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). verify (what is ?) Infobox references

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.