Methyltrimethoxysilane

Methyltrimethoxysilane is an organosilicon compound with the formula CH₃Si(OCH₃)₃. It is a colorless, free-flowing liquid. It is a crosslinker in the preparation of polysiloxane polymers.^[1][2]

Methyltrimethoxysilane

Names
Preferred IUPAC name Trimethoxy(methyl)silane
Other names MTM, Trimethoxymethylsilane
Identifiers
CAS Number	1185-55-3 Y
3D model (JSmol)	Interactive image
ChemSpider	13803
ECHA InfoCard	100.013.350
PubChem CID	14456
UNII	0HI0D71MCI Y
CompTox Dashboard (EPA)	DTXSID3027370
InChI InChI=1S/C4H12O3Si/c1-5-8(4,6-2)7-3/h1-4H3 Key: BFXIKLCIZHOAAZ-UHFFFAOYSA-N InChI=1/C4H12O3Si/c1-5-8(4,6-2)7-3/h1-4H3 Key: BFXIKLCIZHOAAZ-UHFFFAOYAM
SMILES CO[Si](C)(OC)OC
Properties
Chemical formula	C4H12O3Si
Molar mass	136.222 g·mol−1
Appearance	Colorless liquid
Density	0.955 g/cm3
Boiling point	102–104 °C (216–219 °F; 375–377 K)
Solubility in water	hydrolysis
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation, structure and reactivity

Methyltrimethoxysilane is usually prepared from methyltrichlorosilane and methanol:

CH₃SiCl₃ + 3 CH₃OH → CH₃Si(OCH₃)₃ + 3 HCl

Alcoholysis of alkylchlorosilanes typically proceeds via an S_N2 mechanism. Inversion of the configuration is favored during nucleophilic attack when displacing good leaving groups, such as chloride.^[3] In contrast, displacement of poor leaving groups, such as alkoxide, retention is favored.^[4]

Methyltrimethoxysilane is tetrahedral and is often described as sp³ hybridized. It has idealized C_3v point symmetry.

Hydrolysis of MTM proceeds both under acidic and basic conditions. Under acid conditions, rates of successive hydrolyses for methyltrimethoxysilane decreases with each step. Under basic condition the opposite is true.^[1]

See also

• Octadecyltrimethoxysilane