Trimethylsilyl cyanide

Trimethylsilyl cyanide
IUPAC name trimethylsilylformonitrile
Other names Cyanotrimethylsilane; TMS cyanide; Trimethylsilylnitrile; Trimethylsilanecarbonitrile' Trimethylsilylcarbonitrile
Identifiers
Abbreviations	TMSCN
CAS number	7677-24-9 Y
PubChem	82115
ChemSpider	74110 Y
Jmol-3D images	Image 1
SMILES C[Si](C)(C)C#N
InChI InChI=1S/C4H9NSi/c1-6(2,3)4-5/h1-3H3 Y Key: LEIMLDGFXIOXMT-UHFFFAOYSA-N Y
Properties
Molecular formula	C4H9NSi
Molar mass	99.21 g mol−1
Density	0.793 g/mL at 20 °C
Melting point	8-11 °C, 281-284 K, 46-52 °F
Boiling point	114-117 °C, 387-390 K, 237-243 °F
Solubility in water	organic solvents
Solubility	reacts with water
Refractive index (nD)	1.392
Hazards
R-phrases	R11 R26/27/28 R29
S-phrases	S16 S36/37/39 S45
Flash point	1 °C (34 °F)
Y cyanide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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

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 carbamoyl 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.

Safety

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

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

References

1. ^ Livinghouse, T. (1990), "Trimethylsilyl Cyanide: Cyanosilation of p-Benzoquinone", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV7P0517 ; Coll. Vol. 7: 517