Trimethylsilyl cyanide is the chemical compound with the formula (CH3)3SiCN. This volatile liquid consists of a cyanide group, that is CN, attached to a trimethylsilyl group. The molecule is used in organic synthesis as the equivalent of hydrogen cyanide. It is prepared by the reaction of lithium cyanide and trimethylsilyl chloride:[1][2]
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| Names | |||
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| Preferred IUPAC name
Trimethylsilanecarbonitrile | |||
| Other names
Cyanotrimethylsilane; TMS cyanide; Trimethylsilylnitrile; Trimethylsilylcarbonitrile; Trimethylsilylformonitrile
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| Identifiers | |||
3D model (JSmol)
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| Abbreviations | TMSCN | ||
| ChemSpider | |||
| ECHA InfoCard | 100.028.780 | ||
| EC Number |
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |||
| C4H9NSi | |||
| Molar mass | 99.208 g·mol−1 | ||
| Density | 0.793 g/mL at 20 °C | ||
| Melting point | 8 to 11 °C (46 to 52 °F; 281 to 284 K) | ||
| Boiling point | 114 to 117 °C (237 to 243 °F; 387 to 390 K) | ||
| hydrolyzes | |||
| Solubility | organic solvents | ||
Refractive index (nD)
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1.392 | ||
| Hazards | |||
| GHS labelling: | |||
  
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| Danger | |||
| H225, H300, H310, H330, H410 | |||
| P210, P233, P240, P241, P242, P243, P260, P262, P264, P270, P271, P273, P280, P284, P301+P310, P302+P350, P303+P361+P353, P304+P340, P310, P320, P321, P322, P330, P361, P363, P370+P378, P391, P403+P233, P403+P235, P405, P501 | |||
| Flash point | 1 °C (34 °F; 274 K) | ||
| Related compounds | |||
Other anions
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Trimethylsilyl chloride | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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- LiCN + (CH3)3SiCl → (CH3)3SiCN + LiCl
Structure
editThe molecule exhibits the structure of a nitrile-like compound. The compound exists in a rapid equilibrium with a small amount of the isomeric isocyanide (CH3)3SiNC.[3] By contrast, the nearly isostructural tert-butyl nitrile does not readily isomerize to tert-butyl isocyanide. The isocyanide isomer can be stabilized by complexation to metals.[4]
Reactions
editTrimethylsilyl cyanide hydrolyzes to give hydrogen cyanide and trimethylsilanol:
- (CH3)3SiCN + H2O → (CH3)3SiOH + HCN
In its principal application, it adds across carbon-oxygen double bonds, for example in an aldehyde, to form a new carbon-carbon bond:[2]
- RCH=O + (CH3)3SiC≡N → N≡C–CHR–OSi(CH3)3
The product is an O-silylated cyanohydrin.
One use of this reagent is to convert pyridine-N-oxides into 2-cyanopyridine. This transformation is best done in dichloromethane solution using dimethylcarbamoyl chloride as the activating electrophile. It is possible to use benzoyl chloride but the yields and regioselectivity of the addition of the cyano group are lower.
Acetone cyanohydrin can be used to reversibly generate the cyanide anion.[5]
(4)
Safety
editTrimethylsilyl cyanide behaves equivalently to hydrogen cyanide, a potent poison.[2] The compound can be disposed of by using a mixture of alkali hydroxide and bleach.[6]
References
edit- ^ Livinghouse, T. (1981). "Trimethylsilyl Cyanide: Cyanosilation of p-Benzoquinone". Organic Syntheses. 60: 126. doi:10.15227/orgsyn.060.0126.
- ^ a b c Groutas, William C.; Jin, Zhendong; Zhang, Heng (2011). "Cyanotrimethylsilane". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rc276.pub2. ISBN 978-0471936237.
- ^ Booth, M. R.; Frankiss, S. G. (1968). "Trimethylsilyl isocyanide". Chem. Commun. (21): 1347–1348. doi:10.1039/C19680001347.
- ^ Bose, Moumita; Moula, Golam; Begum, Ameerunisha; Sarkar, Sabyasachi (2018). "Synthesis and Characterization of Cyano and Isocyano Complexes of Bis(dithiolato) Molybdenum Using Me3SiCN: A Route to a Cyanide-Bridged Multimer to a Monomer". New Journal of Chemistry. 42 (7): 5580–5592. doi:10.1039/C8NJ00246K.
- ^ Nazarov, N. ; Zav'yalov, I. J. Gen. Chem. USSR (Engl. Transl.) 1954, 24, 475 [C.A., 49, 6139f (1955)].
- ^ MSDS of trimethylsilyl cyanide. (PDF). Gelest. [Jun 13, 2019]