Tetraethyl orthosilicate (TEOS, CAS No. 78-10-4) is an important organosilicon compound and widely used silicon precursor, sol-gel reagent, and crosslinking agent. Its molecular formula is C₈H₂₀O₄Si and molecular weight is 208.33 g/mol.
TEOS readily undergoes hydrolysis and condensation reactions, making it a key precursor for the preparation of silica (SiO₂), siloxane networks, xerogels, aerogels, coatings, nanoparticles, and silicon-containing thin films.
It is also widely used in semiconductor processing, sol-gel chemistry, materials science, surface coatings, and nanomaterial synthesis. Sigma-Aldrich identifies TEOS as a precursor for silicon oxide, oxycarbide, doped silicate, silanol, siloxane polymers, and organosilicon thin films.
TEOS contains four ethoxy groups attached to silicon and can undergo hydrolysis in the presence of water:
Si(OC₂H₅)₄ + H₂O → Si–OH + C₂H₅OH
The resulting silanol groups can subsequently undergo condensation.
Silanol groups can condense through either Si–O–Si formation or alcohol elimination:
Si–OH + HO–Si → Si–O–Si + H₂O
or
Si–OH + Si–OR → Si–O–Si + ROH
Through repeated hydrolysis and condensation, TEOS can form three-dimensional Si–O–Si networks, which is the fundamental principle behind many sol-gel processes.
TEOS is one of the most widely used precursors in sol-gel chemistry.
Applications include:
TEOS is widely used as a silicon source for preparing silica nanoparticles.
Applications include:
High-purity TEOS is used as a silicon precursor for depositing silicon-containing films.
Applications include:
Commercial deposition-grade TEOS products are specifically offered for deposition systems and silicon oxide thin-film preparation.
TEOS can form silica or siloxane networks on suitable substrates.
Applications include:
TEOS is used as a silicon precursor in the development of advanced inorganic and hybrid materials.
Applications include:
TEOS can act as a crosslinking or network-forming component in selected silicon-containing formulations.
Applications include:
Commercial TEOS is available in grades such as >98% GC and ≥99% GC, while specialized deposition-grade material is also available.
TEOS is moisture sensitive and can undergo hydrolysis when exposed to water. TCI recommends storage under inert gas and in a cool, dark place below 15°C.
Commercial specifications report a boiling point around 165–168°C, density around 0.93–0.94 g/mL at 20°C, and flash point around 54°C, although values can vary slightly by measurement method and grade.
Tetraethyl orthosilicate (CAS No. 78-10-4) is widely used in:
A: Tetraethyl orthosilicate (TEOS) is an organosilicon compound with CAS No. 78-10-4, molecular formula C₈H₂₀O₄Si, and molecular weight 208.33 g/mol.
A: TEOS is primarily used as a silicon precursor for silica synthesis, sol-gel processing, thin-film deposition, coatings, and advanced materials research.
A: The molecular formula is C₈H₂₀O₄Si.
A: The molecular weight is 208.33 g/mol. NIST reports 208.3275 g/mol.
A: TEOS stands for Tetraethyl orthosilicate. It is also commonly called Tetraethoxysilane or Tetraethyl silicate.
A: Yes. TEOS is a commonly used silicon precursor for preparing silica nanoparticles, mesoporous silica, and functionalized silica materials.
A: Yes. High-purity TEOS can be used as a silicon precursor for silicon oxide and other silicon-containing thin films in semiconductor and microelectronics processing.
A: Yes. TEOS can undergo hydrolysis in the presence of water, so it should be protected from excessive moisture during storage and handling.
A: TEOS is Tetraethyl orthosilicate, containing ethoxy groups, while TMOS is Tetramethyl orthosilicate, containing methoxy groups. Both are silicon alkoxide precursors used in sol-gel chemistry, but their hydrolysis and processing characteristics differ.
