Tetramethyltin
Encyclopedia
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.
In tetramethyltin, the metal surrounded by four methyl groups in a tetrahedral structure is a heavy analogue of neopentane
.
(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:
A second route to trimethyltin chloride utilizing tetramethyltin involves the reaction of mercury (II) chloride to react with SnMe4.
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.
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.
, tetramethyltin undergoes palladium-catalyzed coupling reactions
with acid chlorides to give methyl ketones:
Synthesis and structure
Tetramethyltin is synthesized by reaction of the Grignard reagent methylmagnesium iodide, with SnCl4, which is synthesized by reacting tin metal with chlorine gas.- 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
Neopentane
Neopentane, also called dimethylpropane, is a double-branched-chain alkane with five carbon atoms. Neopentane is an extremely flammable gas at room temperature and pressure which can condense into a highly volatile liquid on a cold day, in an ice bath, or when compressed to a higher...
.
Precursor to methyltin compounds
Tetramethyltin is a precursor to trimethyltin chlorideTrimethyltin chloride
Trimethyltin chloride is an organotin compound]] with the formula 3SnCl. It is a white solid that is highly toxic and has a stench. It is susceptible to hydrolysis.-Synthesis:...
(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.
- 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.
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.
Applications in organic synthesis
In organic synthesisOrganic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
, tetramethyltin undergoes palladium-catalyzed coupling reactions
Palladium-catalyzed coupling reactions
Palladium compounds are used as a catalyst in many coupling reactions, usually as a homogeneous catalyst. Examples include:* Heck reaction between alkenes and aryl halides* Suzuki reaction between aryl halides and boronic acids...
with acid chlorides to give methyl ketones:
- SnMe4 + RCOCl → RCOMe + Me3SnCl