4795. Hydrogen Cyanide

Nomenclature

CAS number: 74-90-8
Hydrocyanic acid; formonitrile; prussic acid; AC.
CHN; mol wt 27.03.
C 44.43%, H 3.73%, N 51.82%.
HCN.

Description and references

Volatile poison; inhibits cytochrome oxidase and other metalloenzymes by binding to the metal cofactor. Natural sources include cyanogen glycosides in cassava root, lima beans, and seeds of fruits such as apples, peaches, or apricots. Combustion product of nitrogen-containing materials; significant contributor to toxicity from smoke inhalation. Prepd on a large scale by the catalytic oxidation of ammonia-methane mixtures (Andrussow Process): see Andrussow, Angew. Chem. 48, 593 (1935) DOI; Maffezzoni, Chim. Ind. (Milan) 34, 460 (1952); Faith, Keyes & Clark's Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Ed. (Wiley-Interscience, New York, 4th ed., 1975) pp 482-486. Prepd in the lab by acidifying NaCN or K4[Fe(CN)6]: Glemser in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) pp 658-660. GS-MS determn in air samples: Y. Juillet et al., Analyst 130, 977 (2005) DOI PubMed. Oxidation kinetics: P. Dagaut et al., Prog. Energy Combust. Sci. 34, 1 (2008) DOI. Review of synthetic applications: G. Romeder in Handbook of Reagents for Organic Synthesis, Vol. 1 (Wiley, New York, 1999) pp 415-416. Review of analytical methods for determn in blood: A. E. Lindsay et al., Anal. Chim. Acta 511, 185-195 (2004) DOI; of toxicology and human exposure: Toxicological Profile for Cyanide (PB2007-100674, 2006) 341 pp.

Properties

Colorless gas or liquid; characteristic odor of bitter almonds. Intensely poisonous even when mixed with air. Flammable. Burns in air with a blue flame. Flashpoint (closed cup): 0°F (17.8°C). mp 13.4°. bp 25.6°. d(gas) 0.941 (air = 1); d(liq) 0.687. Weak acid, pKa (25°): 9.21. Miscible with water, alc; slightly sol in ether. LC50 in rats, mice, dogs: 544 ppm (5 min), 169 ppm (30 min), 300 ppm (3 min) by inhalation, K. C. Back et al., Reclassification of Materials Listed as Transportation Health Hazards (TSA-20-72-3; PB214-270, 1972).

Caution

Potential symptoms of acute overexposure are abdominal pain, nausea, vomiting; dizziness, headache, confusion; tachypnea, hyperpnea; loss of consciousness, convulsions, cardiorespiratory failure. See NIOSH Pocket Guide to Chemical Hazards (PB2005-149, 2005) p 168; F. J. Baud, Hum. Exp. Toxicol. 26, 191-201 (2007) DOI PubMed.

Use

Reagent in organic synthesis; rodenticide; insect fumigant; chemical warfare agent.