Tetramethyl orthosilicate

Tetramethyl orthosilicate
IUPAC name tetramethoxysilane
Other names tetramethyl orthosilicate; methyl silicate; silicic acid, tetramethyl ester; silicon methoxide; TMOS
Identifiers
CAS number	681-84-5 Y
PubChem	12682
ChemSpider	12161 Y
Jmol-3D images	Image 1
SMILES CO[Si](OC)(OC)OC
InChI InChI=1S/C4H12O4Si/c1-5-9(6-2,7-3)8-4/h1-4H3 Y Key: LFQCEHFDDXELDD-UHFFFAOYSA-N Y InChI=1/C4H12O4Si/c1-5-9(6-2,7-3)8-4/h1-4H3 Key: LFQCEHFDDXELDD-UHFFFAOYAT
Properties
Molecular formula	SiC4H12O4
Molar mass	152.25
Appearance	colourless liquid
Density	1.032
Melting point	4-5 °C
Boiling point	121–122 °C
Solubility in water	organic solvents
Hazards
Main hazards	toxic
Y orthosilicate (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tetramethyl orthosilicate is the chemical compound with the formula Si(OCH₃)₄. This molecule consists of four methyl groups attached to the hypothetical anion SiO₄^4-. The basic properties are similar to the more popular tetraethyl orthosilicate, which is usually preferred because the product of hydrolysis, ethanol, is less toxic than methanol.

Tetramethyl orthosilicate hydrolyzes to SiO₂:

Si(OCH₃)₄ + 2 H₂O → SiO₂ + 4 CH₃OH

In organic synthesis, Si(OCH₃)₄ has been used to convert ketones and aldehydes to the corresponding ketals and acetals, respectively.^[1]

Safety

The hydrolysis of Si(OCH₃)₄ produces insoluble SiO₂ and CH₃OH (methanol). Should this process happen in the eyes, the methanol can cause irreversible eye damage, including blindness.

References

1. ^ Sakurai, H. "Silicon(IV) Methoxide" in Encyclopedia of Reagents for Organic Synthesis 2001 John Wiley & Sons. doi:10.1002/047084289X.rs012

External links

• WebBook page for SiC4H12O4