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Trimethylsilyl chloride

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Trimethylsilyl chloride
TMSCl
Ball-and-stick model of the trimethylsilyl chloride molecule
Ball-and-stick model of the trimethylsilyl chloride molecule
Space-filling model of the trimethylsilyl chloride molecule
Space-filling model of the trimethylsilyl chloride molecule
Names
IUPAC name Trimethylsilyl chloride
Other names Chlorotrimethylsilane
TMSCl
Trimethylchlorosilane
TMCS
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.000.819 Edit this at Wikidata
PubChem CID
RTECS number
  • VV2710000
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C3H9ClSi/c1-5(2,3)4/h1-3H3Key: IJOOHPMOJXWVHK-UHFFFAOYSA-N
  • InChI=1/C3H9ClSi/c1-5(2,3)4/h1-3H3Key: IJOOHPMOJXWVHK-UHFFFAOYAM
SMILES
  • C(C)(C)Cl
Properties
Chemical formula C3H9SiCl
Molar mass 108.64 g/mol
Appearance Colorless liquid, fumes in moist air
Density 0.856 g/cm, 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
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability (yellow): no hazard codeSpecial hazards (white): no code
3 3
Flash point −28 °C
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

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.

Uses

Trimethylsilyl chloride has variety of uses in chemistry, both as a source of the trimethylsilyl group, and as an anhydrous source of chlorides. 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. Trimethylsilylation can also be used to increase the volatility of a compound, 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.

References

  1. L. Birkofer and P. Wegner (1988). "Trimethylsilyl azide". Organic Syntheses; Collected Volumes, vol. 6, p. 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--L-aspartic acid; α tert-butyl ester, β-(2-ethylphenyl]amino]ethyl ester". Organic Syntheses. 81: 235.
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