Tetraethyl Orthosilicate (TEOS)

Tetraethyl orthosilicate is the chemical compound with the formula Si(OC2H5)4. Often abbreviated TEOS, this molecule consists of four ethyl groups attached to SiO44- ion, which is called orthosilicate. As an ion in solution, orthosilicate does not exist. Alternatively TEOS can be considered to be the ethyl ester of orthosilicic acid, Si(OH)4. It is a prototypical alkoxide.
TEOS is mainly used as a crosslinking agent in silicone polymers. Other applications include coatings for carpets and other objects. TEOS is used in the production of aerogel. These applications exploit the reactivity of the Si-OR bonds.