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Trimethylsilyl chloride



Trimethylsilyl chloride
IUPAC name Trimethylsilyl chloride
Other names Chlorotrimethylsilane
TMSCl
Identifiers
CAS number 75-77-4
RTECS number VV2710000
Properties
Molecular formula (CH3)3SiCl
Molar mass 108.94 g/mol
Appearance Colorless liquid, fumes in moist air
Density 0.856 g/cm3, liquid
Melting point

−40 °C (233.2 K)

Boiling point

57 °C (330.2 K)

Solubility in water reacts
Structure
Molecular shape tetrahedral at Si
Hazards
EU classification Flammable (F)
Corrosive (C)
NFPA 704
3
3
0
 
R-phrases R11, R14, R20, R21, R35, R37
S-phrases S16, S26, S36, S37, S39, S45
Flash point −28 °C
Autoignition
temperature
400 °C
Related Compounds
Related halosilanes Trimethylsilyl fluoride
Trimethylsilyl bromide
Trimethylsilyl iodide
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Trimethylsilyl chloride, also known as chlorotrimethylsilane is a silyl halide, with a variety of different uses in chemistry. It has the formula (CH3)3SiCl, and under standard conditions it is a colourless liquid, which is stable in the absence of water. It can be prepared from silicon tetrachloride by nucleophillic substitution of three of the chloride groups with a nucleophillic methyl source such as methyllithium, however the compound is readily available commercially.

Additional recommended knowledge

Uses

Trimethylsilyl chloride has variety of uses in chemistry, both as a source of the trimethylsilyl group, and as an anhydrous source of chloride. Functional groups such as alcohols and amines readily undergo reaction with trimethylsilyl chloride, giving trimethylsilyl ethers and trimethylsilyl amines. These new groups can be used as protecting groups for the original functional group, however the lability of the trimethylsilyl group restricts their utility. The trimethylsilylation can also be used to increase a compounds volatility, enabling gas chromatography of normally non-volatile substances such as glucose. Trimethylsilyl chloride also reacts with metal acetylides to give trimethylsilyl alkynes, which are useful protected forms of alkynes.

The reaction of trimethylsilyl chloride with alcohols gives rise to an equivalent of hydrogen chloride. This reaction can be exploited to create anhydrous solutions of hydrochloric acid in alcohols, which find use in the mild synthesis of esters and acetals from carboxylic acids and ketones respectively.

In the presence of triethylamine and lithium diisopropylamide, enolisable aldehydes, ketones and esters are converted to trimethylsilyl enol ethers. Despite their hydrolytic instability, these compounds have found wide application in organic chemistry; oxidation of the double bond by epoxidation or dihydroxylation can be used to return the original carbonyl group with an alcohol group at the alpha carbon. The trimethylsilyl enol ethers can also be used as masked enolate equivalents in the Mukaiyama aldol addition.

Trimethylsilyl chloride can also be used as a starting material to prepare other trimethylsilyl halides and pseudohalides, such as:

These compounds are produced by an exchange reaction between trimethylsilyl chloride and a salt of the (pseudo)halide (MX):

MX + Me3Si-Cl → MCl + Me3Si-X

Trimethylsilyl chloride is also used to silanize laboratory glassware, making the surfaces more lipophilic.[2]

References

  1. ^ L. Birkofer and P. Wegner (1988). "Trimethylsilyl azide". Org. Synth.; Coll. Vol. 6: 1030. 
  2. ^ Such as in Norbert Zander and Ronald Frank (2005). "The use of polystyrylsulfonyl chloride resin as a solid supported condensation reagent for the formation of esters: Synthesis of N-[(9-fluorenylmethoxy)carbonyl]-L-aspartic acid; α tert-butyl ester, β-(2-ethyl[(1E)-(4-nitrophenyl)azo]phenyl]amino]ethyl ester". Org. Synth. 81: 235. 
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Trimethylsilyl_chloride". A list of authors is available in Wikipedia.
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