Trimethylsilyldiazomethane is the
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 ...
with the formula (CH
3)
3SiCHN
2. It is classified as a
diazo compound
The diazo group is an organic moiety consisting of two linked nitrogen atoms ( azo) at the terminal position. Overall charge neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds or diazoalkanes ...
. Trimethylsilyldiazomethane is a commercially available
reagent used in
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, ...
as a
methylating agent
In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These t ...
and as a source of CH
2 group. Its behavior is akin to the less convenient reagent
diazomethane
Diazomethane is the chemical compound CH2N2, discovered by German chemist Hans von Pechmann in 1894. It is the simplest diazo compound. In the pure form at room temperature, it is an extremely sensitive explosive yellow gas; thus, it is almost ...
.
Preparation
Trimethylsilyldiazomethane can be prepared by treating
(trimethylsilyl)methylmagnesium chloride with
diphenyl phosphorazidate.
The
13C-labeled reagent is also known.
Uses
It is a less explosive alternative to
diazomethane
Diazomethane is the chemical compound CH2N2, discovered by German chemist Hans von Pechmann in 1894. It is the simplest diazo compound. In the pure form at room temperature, it is an extremely sensitive explosive yellow gas; thus, it is almost ...
for the
methylation of
carboxylic acids. It also reacts with alcohols to give methyl ethers, where diazomethane may not.
It has also been employed widely in tandem with
GC-MS for the analysis of various carboxylic compounds which are ubiquitous in nature. The fact that the reaction is rapid and occurs readily makes it attractive. However, it can form artifacts which complicate spectral interpretation. Such artifacts are usually the trimethylsilylmethyl esters, RCO
2CH
2SiMe
3, formed when insufficient
methanol is present. Acid-catalysed methanolysis is necessary to achieve near-quantitative yields of the desired methyl esters, RCO
2Me.
The compound is a reagent in the
Doyle-Kirmse reaction with allyl sulfides and allyl amines.
Trimethylsilyldiazomethyllithium
Trimethylsilyldiazomethane is deprotonated by
butyllithium Butyllithium may refer to one of 5 isomeric organolithium reagents of which 3 are commonly used in chemical synthesis:
* ''n''-Butyllithium, abbreviated BuLi or nBuLi
* ''sec''-Butyllithium, abbreviated ''sec''-BuLi or sBuLi, has 2 stereoisomers, ...
:
:(CH
3)
3SiCHN
2 + BuLi → (CH
3)
3SiCLiN
2 + BuH
The lithio compound is versatile. From it can be prepared other trimethylsilyldiazoalkanes:
:(CH
3)
3SiCLiN
2 + RX → (CH
3)
3SiCRN
2 + LiX
(CH
3)
3SiCLiN
2 reacts with ketones and aldehydes to give, depending on the substituents, acetylenes.
Safety
Trimethylsilyldiazomethane is highly toxic. It has been implicated in the death of at least two chemists, a pharmaceutical worker in Windsor, Nova Scotia, Canada and one in New Jersey.
Inhalation of diazomethane is known to cause
pulmonary edema
Pulmonary edema, also known as pulmonary congestion, is excessive liquid accumulation in the tissue and air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia and respiratory failure. It is due t ...
; trimethylsilyldiazomethane is suspected to behave similarly.
When used as a reagent in organic synthesis to convert carboxylic acids to their methyl esters, trimethylsilyldiazomethane undergoes acid-catalysed
methanolysis
In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. The reaction can ...
, forming diazomethane ''in situ''.
A similar hydrolysis reaction may take place when trimethylsilyldiazomethane comes into contact with water on the surface of a human lung.
Trimethylsilyldiazomethane is nonexplosive.
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References
{{Reflist
Diazo compounds
Reagents for organic chemistry
Carbosilanes
Methylating agents
Trimethylsilyl compounds