Tetramethyltin is an
organometallic compound
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...
with the formula (CH
3)
4Sn. This liquid, one of the simplest
organotin compound
Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Organotin chemistry is part of the wider field of organometallic chemistry. The first organotin compound was diethyltin diiodide (), discovered ...
s, is useful for transition-metal mediated conversion of acid chlorides to methyl ketones and aryl halides to aryl methyl ketones. It is volatile and toxic, so care should be taken when using it in the laboratory.
Synthesis and structure
Tetramethyltin is synthesized by reaction of the Grignard reagent
methylmagnesium iodide
Methylmagnesium chloride is an organometallic compound with the general formula CH3MgCl. This highly flammable, colorless, and moisture sensitive material is the simplest Grignard reagent and is commercially available, usually as a solution in te ...
, with
tin tetrachloride
Tin(IV) chloride, also known as tin tetrachloride or stannic chloride, is an inorganic compound with the formula Sn Cl4. It is a colorless hygroscopic liquid, which fumes on contact with air. It is used as a precursor to other tin compounds. It w ...
,
which is synthesized by reacting tin metal with chlorine gas.
:4 CH
3MgI + SnCl
4 → (CH
3)
4Sn + 4 MgICl
In tetramethyltin, the metal surrounded by four
methyl groups in a
tetrahedral structure is a heavy analogue of
neopentane
Neopentane, also called 2,2-dimethylpropane, is a double-branched-chain alkane with five carbon atoms. Neopentane is a flammable gas at room temperature and pressure which can condense into a highly volatile liquid on a cold day, in an ice bath, ...
.
Applications
Precursor to methyltin compounds
Tetramethyltin is a precursor to
trimethyltin chloride
Trimethyltin chloride is an organotin compound with the formula . It is a white solid that is highly toxic and malodorous. It is susceptible to hydrolysis.
Synthesis
Trimethyltin chloride can be prepared by the redistribution reaction of tetrame ...
(and related methyltin halides), which are precursors to other organotin compounds. These methyltin chlorides are prepared via the so-called Kocheshkov redistribution reaction. Thus, (CH
3)
4Sn and SnCl
4 are allowed to react at temperatures between 100 °C and 200 °C to give (CH
3)
3SnCl as a product:
:SnCl
4 + 3 (CH
3)
4Sn → 4 (CH
3)
3SnCl
A second route to trimethyltin chloride utilizing tetramethyltin involves the reaction of
mercury(II) chloride to react with (CH
3)
4Sn.
[
:4 HgCl2 + 4 (CH3)4Sn → 4 Me3SnCl + 4 MeHgCl
A variety of methyltin compounds are used as precursors for stabilizers in PVC. Di- and trimercaptotin compounds are used to inhibit the dehydrochlorination, which is the pathway for photolytic and thermal degradation of PVC.][
]
Surface functionalization
Tetramethyltin decomposes in the gas phase at about 277 °C; (CH3)4Sn vapor reacts with silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is o ...
to give a (CH3)3Sn-grafted solid.
:(CH3)4Sn + ≡SiOH → ≡SiOSn(CH3)3 + MeH
This reaction is also possible with other alkyl substituents. In a similar process, tetramethyltin has been used to functionalize certain zeolite
Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a metal ion or H+. These ...
s at temperatures as low as −90 °C.
Applications in organic synthesis
In organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...
, tetramethyltin undergoes palladium-catalyzed coupling reactions
In organic chemistry, a cross-coupling reaction is a reaction where two fragments are joined together with the aid of a metal catalyst. In one important reaction type, a main group organometallic compound of the type R-M (R = organic fragment, M = ...
with acid chlorides to give methyl ketones:[{{cite journal , author1=Labadie, J. , author2=Stille, J. , name-list-style=amp , title =Mechanisms of the palladium-catalyzed couplings of acid chlorides with organotin reagents , journal = ]J. Am. Chem. Soc.
The ''Journal of the American Chemical Society'' is a weekly peer-reviewed scientific journal that was established in 1879 by the American Chemical Society. The journal has absorbed two other publications in its history, the ''Journal of Analytical ...
, volume = 105 , issue = 19 , page = 6129 , year = 1983 , doi = 10.1021/ja00357a026
:SnMe4 + RCOCl → RCOMe + Me3SnCl
References
Organotin compounds
Tin(IV) compounds
Methyl complexes