Chlorotrimethylsilane

Trimethylsilyl chloride

Names
Preferred IUPAC name Chloro(trimethyl)silane
Other names Trimethylsilyl chloride Chlorotrimethylsilane TMSCl Trimethylchlorosilane TMCS
Identifiers
CAS Number	75-77-4 Y
3D model (JSmol)	Interactive image
ChemSpider	6157 Y
ECHA InfoCard	100.000.819
PubChem CID	6397
RTECS number	VV2710000
InChI InChI=1S/C3H9ClSi/c1-5(2,3)4/h1-3H3 Y Key: IJOOHPMOJXWVHK-UHFFFAOYSA-N Y InChI=1/C3H9ClSi/c1-5(2,3)4/h1-3H3 Key: IJOOHPMOJXWVHK-UHFFFAOYAM
SMILES C[Si](C)(C)Cl
Properties
Chemical formula	C3H9SiCl
Molar mass	108.64 g/mol
Appearance	Colorless liquid, fumes in moist air
Density	0.856 g/cm3, liquid
Melting point	−40 °C (−40 °F; 233 K)
Boiling point	57 °C (135 °F; 330 K)
Solubility in water	reacts
Magnetic susceptibility (χ)	-77.36·10−6 cm3/mol
Structure
Molecular shape	tetrahedral at Si
Hazards
EU classification (DSD) (outdated)	Flammable (F) Corrosive (C)
R-phrases (outdated)	R11, R14, R20, R21, R35, R37
S-phrases (outdated)	S16, S26, S36, S37, S39, S45
NFPA 704	3 3 2 W
Flash point	−28 °C (−18 °F; 245 K)
Autoignition temperature	400 °C (752 °F; 673 K)
Related compounds
Related halosilanes	Trimethylsilyl fluoride Trimethylsilyl bromide Trimethylsilyl iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Trimethylsilyl chloride, also known as chlorotrimethylsilane is an organosilicon compound (silyl halide), with the formula (CH₃)₃SiCl, often abbreviated Me₃SiCl or TMSCl. It is a colourless volatile liquid that is stable in the absence of water. It is widely used in organic chemistry.

TMSCl is prepared on a large scale by the Direct process, the reaction of methyl chloride with a silicon-copper alloy. The principal target of this process is dimethyldichlorosilane, but substantial amounts of the trimethyl and monomethyl products are also obtained. The relevant reactions are (Me = CH₃):

Typically about 2-4% of the product stream is the monochloride, which forms an azeotrope with MeSiCl₃.

TMSCl is reactive toward nucleophiles, resulting in the replacement of the chloride. In a characteristic reaction of TMSCl, the nucleophile is water, resulting in hydrolysis to give the hexamethyldisiloxane:

The related reaction of trimethylsilyl chloride with alcohols can be exploited to produce anhydrous solutions of hydrochloric acid in alcohols, which find use in the mild synthesis of esters from carboxylic acids and nitriles as well as, acetals from ketones. Similarly, trimethylsilyl chloride is also used to silanize laboratory glassware, making the surfaces more lipophilic.

By the process of silylation, polar functional groups such as alcohols and amines readily undergo reaction with trimethylsilyl chloride, giving trimethylsilyl ethers and trimethylsilyl amines. These new groups "protect" the original functional group by removing the labile protons and decreasing the basicity of the heteroatom. The lability of the Me₃Si-O and Me₃Si-N groups can later be removed ("deprotected"). Trimethylsilylation can also be used to increase the volatility of a compound, enabling gas chromatography of normally nonvolatile substances such as glucose. Trimethylsilyl chloride also reacts with metal acetylides to give trimethylsilyl alkynes such as bis(trimethylsilyl)acetylene. Such derivatives are useful protected forms of alkynes.