Tetramethyltin

Tetramethyltin
Stereo structural formula of tetramethyltin	Ball-and-stick model of the tetramethyltin molecule
Names
	IUPAC name Tetramethylstannane[1]
	Other names Tin tetramethyl
Identifiers
CAS Number	594-27-4 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	3647887
ChEBI	CHEBI:30420 ;
ChemSpider	11171 ;
ECHA InfoCard	100.008.941
EC Number	209-833-6;
Gmelin Reference	1938
PubChem CID	11661;
RTECS number	WH8630000;
UNII	8V4XU9DPBK ;
UN number	3384
CompTox Dashboard (EPA)	DTXSID4052261 ;
	InChI InChI=1S/4CH3.Sn/h4*1H3; Key: VXKWYPOMXBVZSJ-UHFFFAOYSA-N ;
	SMILES C[Sn](C)(C)C;
Properties
Chemical formula	C4H12Sn
Molar mass	178.850 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EU classification (DSD) (outdated)	T+ N
R-phrases (outdated)	R26/27/28, R50/53
S-phrases (outdated)	S26, S27, S28, S45, S60, S61
NFPA 704 (fire diamond)	4 3 1
Flash point	−12 °C (10 °F; 261 K)
Related compounds
Related tetraalkylstannanes	Tetrabutyltin; Tetraethyltin
Related compounds	Neopentane; Tetramethylsilane
	Except where otherwise noted, 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

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

Precursor to methyltin compounds

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

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

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

SnMe₄ + RCOCl → RCOMe + Me₃SnCl

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References

"Tetramethyltin | C4H12Sn". ChemSpider. Retrieved 2013-09-15.
Scott, W. J.; Jones, J. H.; Moretto, A. F. (2002). "Tetramethylstannane". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt070. ISBN 0471936235.
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.
Davies, A. G. (2008). "Tin Organometallics". In Robert H. Crabtree; D. Michael P. Mingos (eds.). Comprehensive Organometallic Chemistry III. Elsevier. pp. 809–883. doi:10.1016/B0-08-045047-4/00054-6. ISBN 9780080450476.
Labadie, J. & 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.

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[1] "Tetramethyltin | C4H12Sn". ChemSpider. Retrieved 2013-09-15.

[Scott-2] Scott, W. J.; Jones, J. H.; Moretto, A. F. (2002). "Tetramethylstannane". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt070. ISBN 0471936235.

[Thoonen-3] 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; D. Michael P. Mingos (eds.). Comprehensive Organometallic Chemistry III. Elsevier. pp. 809–883. doi:10.1016/B0-08-045047-4/00054-6. ISBN 9780080450476.

[5] Labadie, J. & 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.