Lithium cyanide

Lithium cyanide[1][2][3]
Identifiers
CAS number	2408-36-8
PubChem	754-78
ChemSpider	68007
UN number	1935
Jmol-3D images	{{#if:[Li+].[C-]#N|Image 1
SMILES [Li+].[C-]#N
Properties
Molecular formula	LiCN
Molar mass	32.959 g/mol
Appearance	White Powder
Density	1.073 g/cm³ (18 °C)
Melting point	160 °C; 320 °F; 433 K (Dark colored)
Boiling point	N/A
Solubility in water	Soluble
kH	N/A
Structure
Crystal structure	-
Coordination geometry	Fourfold
Hazards
MSDS	742899
EU classification	T+, Very Toxic N, Dangerous for the environment
R-phrases	26/27/28-32-50/53
S-phrases	7-28-29-45-60-61
NFPA 704	0 4 0
Flash point	57 °C; 135 °F; 330 K
Autoignition temperature	N/A
Related compounds
Other anions	CN-
Other cations	Li+
Related compounds	HCN
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Lithium cyanide is an inorganic compound with the chemical formula LiCN. It is a white powder at room temperature. Lithium cyanide is commonly used as a reagent in inorganic/organometallic reactions. Lithium cyanide can be found in the environment from the reaction of lithium and acetonitrile, two compounds found in lithium sulfur oxide batteries. When the compound is exposed to the environment it can produce toxic fumes with weak acids found in nature.

Properties

Stability and reactivity

Lithium cyanide as a solid is stable under room temperature. LiCN, when melted at 160 °C, is highly hygroscopic. The compound decomposes to cyanamide and carbon when heated to a temperature close to but below 600°C. When acids, chlorates, and strong oxidizing agents react with LiCN, HCN is formed. HCN vapors are very toxic and reactive. If LiCN is heated in fire carbon dioxide CO2, nitrous oxides NOx, and lithium oxides will form.^[4]

Reactions

Synthesis and production

Li + R-CN → LiCN

Li + HCN(Benzene) → LiCN

Lithium cyanide can be synthesized in high yields with liquid hydrogen cyanide and n-butyllithium. Other methods exist with the fundamental idea of adding the lithium cation to the cyanide anion.^[4]

Cyanation

RX + LiCN —THF→ RCN

Lithium cyanide is commonly used as a reagent in synthesizes of cyanide compounds, for example halide cyanides. The reagent offers advantages by allowing non-aqeous methods of cyanation.^[5]

Environmental exposure

Lithium cyanide is an inorganic compound not commonly found in nature without human involvement. The most obtainable source of lithium is through lithium batteries. Specifically, lithium sulfur dioxide batteries can lead to the formation of lithium cyanide form the reaction between the two compounds found inside the battery, elemental lithium and acetonitrile. When lithium cyanide is introduced the environment, it can react with acids or strong oxidizing agents to produce toxic HCN vapors in the environment or produce carbon dioxide, nitrous oxides, and lithium oxides if introduced to fire. Concerns of the hazardousness of lithium sulfur oxide batteries waste were raised as lithium batteries become more obtainable. The US Environmental Protection Agency and Department of Defense evaluated the lithium sulfur oxide batteries and concluded that LiCN formation was one of the compounds leading to the hazardous waste.^[6][7]

References