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| Names | |||
|---|---|---|---|
| Preferred IUPAC name Chlorotri(methyl)silane | |||
| Other names Trimethylsilyl chloride Chlorotrimethylsilane TMSCl Trimethylchlorosilane TMCS | |||
| Identifiers | |||
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3D model (JSmol) | |||
| ChemSpider |
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| ECHA InfoCard | 100.000.819 | ||
| EC Number |
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| RTECS number |
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| UNII | |||
| UN number | 1298 | ||
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| Properties | |||
| 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) | ||
| Reacts | |||
| −77.36·10−6 cm3/mol | |||
| Structure | |||
| Tetrahedral at Si | |||
| Hazards | |||
| GHS labelling: | |||
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| Danger | |||
| H225,H301,H312,H314,H331,H351 | |||
| P201,P202,P210,P233,P240,P241,P242,P243,P260,P264,P270,P271,P280,P281,P301+P310,P301+P330+P331,P302+P352,P303+P361+P353,P304+P340,P305+P351+P338,P308+P313,P310,P311,P312,P321,P322,P330,P363,P370+P378,P403+P233,P403+P235,P405,P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | −28 °C (−18 °F; 245 K) | ||
| 400 °C (752 °F; 673 K) | |||
| Related compounds | |||
Relatedhalosilanes | |||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Trimethylsilyl chloride, also known aschlorotrimethylsilane is anorganosilicon compound (silyl halide), with the formula(CH3)3SiCl, often abbreviatedMe3SiCl orTMSCl. 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 thedirect process, the reaction ofmethyl chloride with a silicon-copper alloy. The principal target of this process isdimethyldichlorosilane, but substantial amounts of the trimethyl and monomethyl products are also obtained.[1] The relevant reactions are (Me =methyl,CH3):
Typically about 2–4% of the product stream is the monochloride, which forms anazeotrope withMeSiCl3.
TMSCl is reactive toward nucleophiles, resulting in the replacement of the chloride. In a characteristic reaction of TMSCl, the nucleophile is water, resulting inhydrolysis to give thehexamethyldisiloxane:The related reaction of trimethylsilyl chloride with alcohols can be exploited to produceanhydrous solutions ofhydrochloric acid in alcohols, which find use in the mild synthesis ofesters fromcarboxylic acids andnitriles as well as,acetals fromketones. Similarly, trimethylsilyl chloride is also used to silanizelaboratory glassware, making the surfaces morelipophilic.[2]
By the process ofsilylation, polar functional groups such asalcohols andamines readily undergo reaction with trimethylsilyl chloride, givingtrimethylsilyl ethers andtrimethylsilylamines. These new groups"protect" the original functional group by removing the labile protons and decreasing the basicity of the heteroatom. Thelability of theMe3Si−O andMe3Si−N groups allow them to be easily removed afterwards ("deprotected").Trimethylsilylation can also be used to increase the volatility of a compound, enablinggas chromatography of normally nonvolatile substances such asglucose.
Trimethylsilyl chloride also reacts with carbanions to give trimethylsilyl derivatives.[3] Lithium acetylides react to give trimethylsilylalkynes such asbis(trimethylsilyl)acetylene. Such derivatives are useful protected forms of alkynes.
In the presence oftriethylamine andlithium diisopropylamide,enolisablealdehydes,ketones andesters are converted totrimethylsilyl enol ethers.[4] Despite their hydrolytic instability, these compounds have found wide application in organic chemistry;oxidation of thedouble bond byepoxidation ordihydroxylation can be used to return the originalcarbonyl group with analcohol group at the alpha carbon. The trimethylsilylenol ethers can also be used as maskedenolate equivalents in theMukaiyama aldol addition.
Dehydration of metal chlorides with trimethylsilyl chloride in THF gives the solvate as illustrated by the case ofchromium trichloride:[5]
Trimethylsilyl chloride is used to prepare other trimethylsilyl halides andpseudohalides, including trimethylsilyl fluoride, trimethylsilyl bromide,trimethylsilyl iodide,trimethylsilyl cyanide,trimethylsilyl azide,[6] and trimethylsilyl trifluoromethanesulfonate (TMSOTf). These compounds are produced by asalt metathesis reaction between trimethylsilyl chloride and a salt of the (pseudo)halide (MX):TMSCl, lithium, and nitrogen molecule react to givetris(trimethylsilyl)amine, under catalysis bynichrome wire orchromium trichloride:Using this approach, atmospheric nitrogen can be introduced into organic substrate. For example, tris(trimethylsilyl)amine reacts with α,δ,ω-triketones to give tricyclicpyrroles.[7]
Reduction of trimethylsilyl chloride givehexamethyldisilane:
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