Trimethylsilyl chloride, also known as chlorotrimethylsilane is an

organosilicon compound Organosilicon compounds are organometallic compounds containing carbon–silicon bonds. Organosilicon chemistry is the corresponding science of their preparation and properties. Most organosilicon compounds are similar to the ordinary organic c ...

(

silyl halide Organosilicon compounds are organometallic compounds containing carbon– silicon bonds. Organosilicon chemistry is the corresponding science of their preparation and properties. Most organosilicon compounds are similar to the ordinary organic ...

), 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.

Preparation

TMSCl is prepared on a large scale by the ''

direct process The direct process, also called the direct synthesis, Rochow process, and Müller-Rochow process is the most common technology for preparing organosilicon compounds on an industrial scale. It was first reported independently by Eugene G. Rochow and ...

'', the reaction of

methyl chloride Chloromethane, also called methyl chloride, Refrigerant-40, R-40 or HCC 40, is an organic compound with the chemical formula . One of the haloalkanes, it is a colorless, odorless, flammable gas. Methyl chloride is a crucial reagent in industria ...

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): : x MeCl + Si → Me₃SiCl, Me₂SiCl₂, MeSiCl₃, other products Typically about 2–4% of the product stream is the monochloride, which forms an

azeotrope An azeotrope () or a constant heating point mixture is a mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation.Moore, Walter J. ''Physical Chemistry'', 3rd e Prentice-Hall 1962, pp. 140–142 This ...

with MeSiCl₃.

Reactions and uses

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 Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysi ...

to give the hexamethyldisiloxane: :2 Me₃SiCl + H₂O → Me₃Si-O-SiMe₃ + 2 HCl The related reaction of trimethylsilyl chloride with alcohols can be exploited to produce

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achi ...

solutions of

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dige ...

in alcohols, which find use in the mild synthesis of

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...

s from

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxyli ...

s and

nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix '' cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including me ...

s as well as,

acetal In organic chemistry, an acetal is a functional group with the connectivity . Here, the R groups can be organic fragments (a carbon atom, with arbitrary other atoms attached to that) or hydrogen, while the R' groups must be organic fragments n ...

s from

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double b ...

s. Similarly, trimethylsilyl chloride is also used to silanize laboratory glassware, making the surfaces more lipophilic.

Silylation in organic synthesis

By the process of

silylation Silylation is the introduction of one or more (usually) substituted silyl groups (R3Si) to a molecule. The process is the basis of organosilicon chemistry. Of organic compounds Alcohols, carboxylic acids, amines, thiols, and phosphates can be sil ...

, polar functional groups such as

alcohols In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is ...

and

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...

s readily undergo reaction with trimethylsilyl chloride, giving trimethylsilyl ethers and

trimethylsilyl A trimethylsilyl group (abbreviated TMS) is a functional group in organic chemistry. This group consists of three methyl groups bonded to a silicon atom minus;Si(CH3)3 which is in turn bonded to the rest of a molecule. This structural group is ch ...

s. 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").

Trimethylsilyl A trimethylsilyl group (abbreviated TMS) is a functional group in organic chemistry. This group consists of three methyl groups bonded to a silicon atom minus;Si(CH3)3 which is in turn bonded to the rest of a molecule. This structural group is ch ...

ation can also be used to increase the volatility of a compound, enabling

gas chromatography Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substanc ...

of normally nonvolatile substances such as

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

. Trimethylsilyl chloride also reacts with carbanions to give trimethylsilyl derivatives. Lithium acetylides react to give trimethylsilyl alkynes such as bis(trimethylsilyl)acetylene. Such derivatives are useful protected forms of alkynes. In the presence of

triethylamine Triethylamine is the chemical compound with the formula N(CH2CH3)3, commonly abbreviated Et3N. It is also abbreviated TEA, yet this abbreviation must be used carefully to avoid confusion with triethanolamine or tetraethylammonium, for which TEA ...

and lithium diisopropylamide,

enol In organic chemistry, alkenols (shortened to enols) are a type of reactive structure or intermediate in organic chemistry that is represented as an alkene ( olefin) with a hydroxyl group attached to one end of the alkene double bond (). T ...

isable

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl gro ...

s and

s are converted to

enol ether In organic chemistry an enol ether is an alkene with an alkoxy substituent. The general structure is R2C=CR-OR where R = H, alkyl or aryl. A common subfamily of enol ethers are vinyl ethers, with the formula ROCH=CH2. Important enol ethers incl ...

s. Despite their hydrolytic instability, these compounds have found wide application in organic chemistry;

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...

of the

double bond In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betwee ...

by epoxidation or dihydroxylation can be used to return the original carbonyl group with an

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

group at the alpha carbon. The

s can also be used as masked enolate equivalents in the

Mukaiyama aldol addition The Mukaiyama aldol addition is an organic reaction and a type of aldol reaction between a silyl enol ether and an aldehyde or formate. The reaction was discovered by Teruaki Mukaiyama (1927–2018) in 1973. His choice of reactants allows ...

Dehydrations

Dehydration of metal chlorides with trimethylsilyl chloride in THF gives the solvate as illustrated by the case of chromium trichloride: :CrCl₃ + 12 Me₃SiCl → CrCl₃(THF)₃ + 6 (Me₃Si)₂O + 12 HCl

Other reactions

Trimethylsilyl chloride is used to prepare other trimethylsilyl halides and pseudohalides, including trimethylsilyl fluoride, trimethylsilyl bromide, trimethylsilyl iodide,

trimethylsilyl cyanide Trimethylsilyl cyanide is the chemical compound with the formula (CH3)3SiCN. This volatile liquid consists of a cyanide group, that is CN, attached to a trimethylsilyl group. The molecule is used in organic synthesis as the equivalent of hydrogen ...

, trimethylsilyl azide, and trimethylsilyl trifluoromethanesulfonate (TMSOTf). These compounds are produced by a salt metathesis reaction between trimethylsilyl chloride and a salt of the (pseudo)halide (MX): :MX + Me₃Si-Cl → MCl + Me₃Si-X TMSCl, lithium, and nitrogen molecule react to give tris(trimethylsilyl)amine, under catalysis by

nichrome Nichrome (also known as NiCr, nickel-chromium or chromium-nickel) is a family of alloys of nickel, chromium, and often iron (and possibly other elements) commonly used as resistance wire, heating elements in devices like toasters, electrical kett ...

wire or chromium trichloride: :3 Me₃SiCl + 3 Li + → (Me₃Si)₃N + 3 LiCl Using this approach, atmospheric nitrogen can be introduced into organic substrate. For example, tris(trimethylsilyl)amine reacts with α,δ,ω-tri

s to give tricyclic

pyrrole Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4 H4 NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., ''N''-meth ...

s. Reduction of trimethylsilyl chloride give hexamethyldisilane: :2 Me₃SiCl + 2 Na → 2 NaCl + Me₃Si-SiMe₃

References

{{DEFAULTSORT:Trimethylsilyl Chloride Reagents for organic chemistry Trimethylsilyl compounds Chlorosilanes