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| Names | |||
|---|---|---|---|
| IUPAC name
Formonitrile[2]
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| Systematic IUPAC name
Methanenitrile[2] | |||
Other names
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| Identifiers | |||
3D model (JSmol)
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| ChEBI | |||
| ChemSpider | |||
| ECHA InfoCard | 100.000.747 | ||
| EC Number |
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| KEGG | |||
| MeSH | Hydrogen+Cyanide | ||
PubChem CID
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| RTECS number |
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| UNII | |||
| UN number | 1051 | ||
CompTox Dashboard (EPA)
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| Properties | |||
| HCN | |||
| Molar mass | 27.0253 g/mol | ||
| Appearance | Colorless liquid or gas | ||
| Odor | bitter almond-like[3] | ||
| Density | 0.6876 g/cm3[4] | ||
| Melting point | −13.29 °C (8.08 °F; 259.86 K)[4] | ||
| Boiling point | 26 °C (79 °F; 299 K)[4]: 4.67 | ||
| Miscible | |||
| Solubility in ethanol | Miscible | ||
| Vapor pressure | 100 kPa (25 °C)[4]: 6.94 | ||
Henry's law
constant (kH) |
75 μmol Pa−1 kg−1 | ||
| Acidity (pKa) | 9.21 (in water),
12.9 (in DMSO)[5] | ||
| Basicity (pKb) | 4.79 (cyanide anion) | ||
| Conjugate acid | Hydrocyanonium | ||
| Conjugate base | Cyanide | ||
Refractive index (nD)
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1.2675[6] | ||
| Viscosity | 0.183 mPa·s (25 °C)[4]: 6.231 | ||
| Structure | |||
| tetragonal (>170 K) orthorhombic (<170 K)[7] | |||
| C∞v | |||
| Linear | |||
| 2.98 D | |||
| Thermochemistry | |||
Heat capacity (C)
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35.9 J K−1 mol−1 (gas)[4]: 5.19 | ||
Std molar
entropy (S⦵298) |
201.8 J K−1 mol−1 | ||
Std enthalpy of
formation (ΔfH⦵298) |
135.1 kJ mol−1 | ||
| Hazards | |||
| GHS labelling: | |||
   
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| Danger | |||
| H225, H300+H310+H330, H319, H336, H370, H410 | |||
| P210, P261, P305+P351+P338 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | −17.8 °C (0.0 °F; 255.3 K) | ||
| 538 °C (1,000 °F; 811 K) | |||
| Explosive limits | 5.6% – 40.0%[8] | ||
| Lethal dose or concentration (LD, LC): | |||
LC50 (median concentration)
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501 ppm (rat, 5 min) 323 ppm (mouse, 5 min) 275 ppm (rat, 15 min) 170 ppm (rat, 30 min) 160 ppm (rat, 30 min) 323 ppm (rat, 5 min)[9] | ||
LCLo (lowest published)
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200 ppm (mammal, 5 min) 36 ppm (mammal, 2 hr) 107 ppm (human, 10 min) 759 ppm (rabbit, 1 min) 759 ppm (cat, 1 min) 357 ppm (human, 2 min) 179 ppm (human, 1 hr)[9] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible)
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TWA 10 ppm (11 mg/m3) [skin][8] | ||
REL (Recommended)
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ST 4.7 ppm (5 mg/m3) [skin][8] | ||
IDLH (Immediate danger)
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50 ppm[8] | ||
| Related compounds | |||
Related alkanenitriles
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Hydrogen cyanide (formerly known as prussic acid) is a chemical compound with the formula HCN and structural formula H−C≡N. It is a highly toxic and flammable liquid that boils slightly above room temperature, at 25.6 °C (78.1 °F). HCN is produced on an industrial scale and is a highly valued precursor to many chemical compounds ranging from polymers to pharmaceuticals. Large-scale applications are for the production of potassium cyanide and adiponitrile, used in mining and plastics, respectively.[10] It is more toxic than solid cyanide compounds due to its volatile nature. A solution of hydrogen cyanide in water, represented as HCN, is called hydrocyanic acid. The salts of the cyanide anion are known as cyanides.
Whether hydrogen cyanide is an organic compound or not is a topic of debate among chemists, and opinions vary from author to author. Traditionally, it is considered inorganic by a significant number of authors. Contrary to this view, it is considered organic by other authors, because hydrogen cyanide belongs to the class of organic compounds known as nitriles which have the formula R−C≡N, where R is typically organyl group (e.g., alkyl or aryl) or hydrogen.[11] In the case of hydrogen cyanide, the R group is hydrogen H, so the other names of hydrogen cyanide are methanenitrile and formonitrile.[2]
- ^ "hydrogen cyanide (CHEBI:18407)". Chemical Entities of Biological Interest. UK: European Bioinformatics Institute. 18 October 2009. Main. Retrieved 2012-06-04.
- ^ a b c "Hydrogen Cyanide". PubChem. National Center for Biotechnology Information.
- ^ Simeonova, Fina Petrova; Fishbein, Lawrence (2004). Hydrogen cyanide and cyanides : human health aspects (Report). World Health Organization. ISBN 9241530618. ISSN 1020-6167.
- ^ a b c d e f Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). CRC Press. ISBN 978-1439855119.
- ^ Evans DA. "pKa's of Inorganic and Oxo-Acids" (PDF). Archived (PDF) from the original on 2022-10-09. Retrieved June 19, 2020.
- ^ Patnaik P (2002). Handbook of Inorganic Chemicals. McGraw-Hill. ISBN 978-0070494398.
- ^ Schulz, Axel; Surkau, Jonas (2022-09-21). "Main group cyanides: from hydrogen cyanide to cyanido-complexes". Reviews in Inorganic Chemistry. 43 (1). Walter de Gruyter GmbH: 49–188. doi:10.1515/revic-2021-0044. ISSN 0193-4929.
- ^ a b c d NIOSH Pocket Guide to Chemical Hazards. "#0333". National Institute for Occupational Safety and Health (NIOSH).
- ^ a b "Hydrogen cyanide". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^ Gail, E.; Gos, S.; Kulzer, R.; Lorösch, J.; Rubo, A.; Sauer, M. "Cyano Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_159.pub2. ISBN 978-3527306732.
- ^ "Human Metabolome Database: Showing metabocard for Hydrogen cyanide (HMDB0060292)".