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Trimethylsilyl cyanide

Trimethylsilyl cyanide
IUPAC name trimethylsilylformonitrile
Other names Cyanotrimethylsilane TMSCN Trimethylsilylnitrile
Molecular formula C4H9SiN
CAS number 7677-24-9
Molar mass 99.21 g/mol
Density 0.793 g/mL at 20 °C
Melting point

8-11 °C

Boiling point

114-117 °C

Solubility in water organic solvents
Solubility reacts with water
Refractive index (nD) 1.392
R-phrases 11-26/27/28-29
S-phrases 16-36/37/39-45
Flash point 34 °F
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and 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

In its principal reaction, it adds across carbon-oxygen double bonds, for example in an aldehyde:

RCHO + (CH3)3SiCN → RCH(CN)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 dimethyl carbomyl 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.


Trimethylsilyl cyanide is treated with care since it hydrolyzes to give hydrogen cyanide:

2 (CH3)3SiCN + H2O → (CH3)3SiOSi(CH3)3 + 2 HCN


  1. ^ Livinghouse, T. (1990). "Trimethylsilyl Cyanide: Cyanosilation of p-Benzoquinone". Org. Synth.; Coll. Vol. 7: 517. 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Trimethylsilyl_cyanide". A list of authors is available in Wikipedia.
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