Lithium cyanide

Lithium cyanide[1][2][3]
Identifiers
2408-36-8
ChemSpider 68007
Jmol-3D images Image
PubChem 754-78
UN number 1935
Properties
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
Soluble
N/A
Structure
Crystal structure -
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
Flammability code 0: Will not burn. E.g., water Health code 4: Very short exposure could cause death or major residual injury. E.g., VX gas Reactivity (yellow): no hazard code Special hazards (white): no codeNFPA 704 four-colored diamond
0
4
Flash point 57 °C (135 °F; 330 K)
N/A
Related compounds
Related compounds
 Sodium cyanide, Potassium cyanide, Hydrogen Cyanide
Except where noted otherwise, data is 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

  1. ↑ J. A. Lely,, J. M. Bijvoet (1942), "The Crystal Structure of Lithium Cyanide", Recueil des Travaux Chimiques des Pays-Bas 61, London: WILEY-VCH Verlag
  2. ↑ Haynes, W.M (2013), "Bernard Lewis", in Bruno, Thomas., Handbook of Chemistry and Physics (93 ed.), Boca Raton, Florida: Fitzroy Dearborn
  3. ↑ Material Safety Data Sheet: Lithium Cyanide, 0.5M Solution in N,N-Dimethylformamide, Fisher Scientific, 16 June 1999
  4. ↑ 4.0 4.1 "Cyanides". E. I. du Pont de Nemours & Co., Inc. Retrieved 2012-11-02.
  5. ↑ "Non-aqueous cya nation of halides using lithium cyanide". Elsevier. Retrieved 2012-10-17.
  6. ↑ "Evaluation of Lithium Sulfur Dioxide Batteries" (PDF). U.S. Army Communications - Electronics Command and U.S. Army Electronics Research and Development Command. Retrieved 2012-10-23.
  7. ↑ "Regulatory status of spent and/or discarded lithium-sulfur dioxide (Li/S02) batteries". United States Environmental Protection Agency. 7 March 1984. Retrieved 2012-10-23.