Trimethylsilyl cyanide

Trimethylsilyl cyanide
Names
	Preferred IUPAC name Trimethylsilanecarbonitrile
	Other names Cyanotrimethylsilane; TMS cyanide; Trimethylsilylnitrile; Trimethylsilylcarbonitrile; Trimethylsilylformonitrile
Identifiers
CAS Number	7677-24-9 ;
3D model (JSmol)	Interactive image;
Abbreviations	TMSCN
ChemSpider	74110 ;
ECHA InfoCard	100.028.780
EC Number	231-657-3;
PubChem CID	82115;
CompTox Dashboard (EPA)	DTXSID9064766 ;
	InChI InChI=1S/C4H9NSi/c1-6(2,3)4-5/h1-3H3 Key: LEIMLDGFXIOXMT-UHFFFAOYSA-N ; InChI=1/C4H9NSi/c1-6(2,3)4-5/h1-3H3 Key: LEIMLDGFXIOXMT-UHFFFAOYAM;
	SMILES C[Si](C)(C)C#N;
Properties
Chemical formula	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)
Solubility in water	hydrolyzes
Solubility	organic solvents
Refractive index (nD)	1.392
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H300, H310, H330, H410
Precautionary statements	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	Trimethylsilyl chloride
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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]

LiCN + (CH₃)₃SiCl → (CH₃)₃SiCN + LiCl

Structure

The molecule exhibits the expected structure of a nitrile-like compound. The compound exists in a facile equilibrium with a small amount of the isomeric isocyanide (CH₃)₃SiNC.^[2] By contrast, the nearly isostructural tert-butyl nitrile does not readily isomerize to tert-butyl isocyanide.

Reactions

Trimethylsilyl 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:

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.^[3]

(4)

Safety

This chemical is rated as "Fatal if swallowed, in contact with skin or if inhaled" as it hydrolyzes in the presence of moisture to give hydrogen cyanide gas.

Disposal by using dilute solution of alkali hydroxide is recommended.^[4]

References

^ Livinghouse, T. (1990). "Trimethylsilyl Cyanide: Cyanosilation of p-Benzoquinone". Organic Syntheses; Collected Volumes, vol. 7, p. 517.
^ Booth, M. R.; Frankiss, S. G. (1968). "Trimethylsilyl isocyanide". Chem. Commun. (21): 1347–1348. doi:10.1039/C19680001347.
^ 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]

[1] Livinghouse, T. (1990). "Trimethylsilyl Cyanide: Cyanosilation of p-Benzoquinone". Organic Syntheses; Collected Volumes, vol. 7, p. 517.

[2] Booth, M. R.; Frankiss, S. G. (1968). "Trimethylsilyl isocyanide". Chem. Commun. (21): 1347–1348. doi:10.1039/C19680001347.

[3] Nazarov, N. ; Zav'yalov, I. J. Gen. Chem. USSR (Engl. Transl.) 1954, 24, 475 [C.A., 49, 6139f (1955)].

[4] MSDS of trimethylsilyl cyanide. (PDF). Gelest. [Jun 13, 2019]

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