Tetramethyltin

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Tetramethyltin
Stereo structural formula of tetramethyltin
Identifiers
CAS number 594-27-4 YesY
PubChem 11661
ChemSpider 11171 YesY
EC number 209-833-6
UN number 3384
ChEBI CHEBI:30420 YesY
RTECS number WH8630000
Beilstein Reference 3647887
Gmelin Reference 1938
Jmol-3D images Image 1
Properties
Molecular formula C4H12Sn
Molar mass 178.85 g mol−1
Appearance Colorless liquid
Density 1.291 g cm-3
Melting point −54 °C (−65 °F; 219 K)
Boiling point 74 to 76 °C (165 to 169 °F; 347 to 349 K)
Hazards
EU classification Very Toxic T+Dangerous for the Environment (Nature) N
R-phrases R26/27/28, R50/53
S-phrases S26, S27, S28, S45, S60, S61
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point −12 °C (10 °F; 261 K)
Related compounds
Related tetraalkylstannanes Tetrabutyltin

Tetraethyltin

Related compounds Neopentane

Tetramethylsilane

Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Tetramethyltin is an organometallic compound with the formula (CH3)4Sn. This liquid, one of the simplest organotin compounds, 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[edit]

Tetramethyltin is synthesized by reaction of the Grignard reagent methylmagnesium iodide, with SnCl4,[2] which is synthesized by reacting tin metal with chlorine gas.[3]

4 CH3MgI + SnCl4 → (CH3)4Sn + 4 MgICl

In tetramethyltin, the metal surrounded by four methyl groups in a tetrahedral structure is a heavy analogue of neopentane.

Applications[edit]

Precursor to methyltin compounds[edit]

Tetramethyltin is a precursor to trimethyltin chloride (and related methyltin halides), which are precursors to other organotin compounds. These methyltin chlorides are prepared via the so-called Kocheshkov redistribution reaction. Thus, SnMe4 and SnCl4 are allowed to react at temperatures between 100 °C and 200 °C to give Me3SnCl as a product:

SnCl4 + 3 SnMe4 → 4 Me3SnCl

A second route to trimethyltin chloride utilizing tetramethyltin involves the reaction of mercury (II) chloride to react with SnMe4.[2]

4 HgCl2 + 4 SnMe4 → 4 Me3SnCl + 4 MeHgCl

A variety of methyltin compounds are used as precursors for stabilizers in PVC. Di- and trimercapto tin compounds are used to inhibit the dehydrochlorination, which is the pathway for photolytic and thermal degradation of PVC.[3]

Surface functionalization[edit]

Tetramethyltin decomposes in the gas phase at about 277 °C (550 K) Me4Sn vapor reacts with silica to give Me3Sn-grafted solid.

Me4Sn + ≡SiOH → ≡SiOSnMe3 + MeH

This reaction is also possible with other alkyl substituents. In a similar process, tetramethyltin has been used to functionalize certain zeolites at temperatures as low as -90 °C.[4]

Applications in organic synthesis[edit]

In organic synthesis, tetramethyltin undergoes palladium-catalyzed coupling reactions with acid chlorides to give methyl ketones:[5]

SnMe4 + RCOCl → RCOMe + Me3SnCl

References[edit]

  1. ^ "Tetramethyltin | C4H12Sn". ChemSpider. Retrieved 2013-09-15. 
  2. ^ a b Scott, W. J.; Jones, J. H.; Moretto, A. F. (2002). "Tetramethylstannane". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt070. 
  3. ^ a b Thoonen, S. H. L.; Deelman, B.; van Koten, G; (2004). "Synthetic Aspects of Tetraorganotins and Organotin(IV) Halides". Journal of Organometallic Chemistry 689 (13): 2145–2157. doi:10.1016/j.jorganchem.2004.03.027. 
  4. ^ Davies, A. G. (2008). "Tin Organometallics". In Robert H. Crabtree and D. Michael P. Mingos. Comprehensive Organometallic Chemistry III. Elsevier. pp. 809–883. doi:10.1016/B0-08-045047-4/00054-6. 
  5. ^ Labadie, J. and Stille, J. (1983). "Mechanisms of the palladium-catalyzed couplings of acid chlorides with organotin reagents". J. Am. Chem. Soc. 105 (19): 6129. doi:10.1021/ja00357a026.