Tetramethyl orthosilicate, Tetramethoxysilane, 99.0+%

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.

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