Hydrogen cyanide

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Hydrogen cyanide
Ball and stick model of hydrogen cyanide Hydrogen-cyanide-3D-balls.svg
Ball and stick model of hydrogen cyanide
Spacefill model of hydrogen cyanide Hydrogen-cyanide-3D-vdW.svg
Spacefill model of hydrogen cyanide
Hydrogen cyanide.jpg
IUPAC name
Formonitrile [1] [2]
Systematic IUPAC name
Methanenitrile [2]
Other names
  • Formic anammonide
  • Hydridonitridocarbon [3]
  • Hydrocyanic acid (aqueous)
  • Hydrogen cyanide (gas form)
  • Prussic acid
  • Cyanane
3D model (JSmol)
ECHA InfoCard 100.000.747 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 200-821-6
MeSH Hydrogen+Cyanide
PubChem CID
RTECS number
  • MW6825000
UN number 1051
  • InChI=1S/CHN/c1-2/h1H X mark.svgN
  • C#N
Molar mass 27.0253 g/mol
AppearanceColorless liquid or gas
Odor Almond-like [4]
Density 0.6876 g/cm3 [5]
Melting point −13.29 °C (8.08 °F; 259.86 K) [5]
Boiling point 26 °C (79 °F; 299 K) [5] :4.67
Solubility in ethanol Miscible
Vapor pressure 100 kPa (25 °C) [5] :6.94
75 μmol Pa−1 kg−1
Acidity (pKa)9.21 (in water),

12.9 (in DMSO) [6]

Basicity (pKb)4.79 (cyanide anion)
Conjugate acid Hydrocyanonium
Conjugate base Cyanide
1.2675 [7]
Viscosity 0.183 mPa·s (25 °C) [5] :6.231
tetragonal (>170 K)
orthorhombic (<170 K) [8]
2.98 D
35.9 J K−1 mol−1 (gas) [5] :5.19
Std molar
201.8 J K−1 mol−1
135.1 kJ mol−1
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-skull.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
H225, H300, H310, H319, H330, H336, H370, H410
P210, P261, P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704.svgHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
Flash point −17.8 °C (0.0 °F; 255.3 K)
538 °C (1,000 °F; 811 K)
Explosive limits 5.6% – 40.0% [9]
Lethal dose or concentration (LD, LC):
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) [10]
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) [10]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 10 ppm (11 mg/m3) [skin] [9]
REL (Recommended)
ST 4.7 ppm (5 mg/m3) [skin] [9]
IDLH (Immediate danger)
50 ppm [9]
Related compounds
Related alkanenitriles
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Hydrogen cyanide (once 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. [11] 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 significant part of authors. Contrary to them, 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. [12] In the case of hydrogen cyanide, the R group is hydrogen H, so the other names of hydrogen cyanide are methanenitrile and formonitrile. [2]

Structure and general properties

Hydrogen cyanide is a linear molecule, with a triple bond between carbon and nitrogen. The tautomer of HCN is HNC, hydrogen isocyanide.[ citation needed ]

HCN has a faint bitter almond-like odor that some people are unable to detect owing to a recessive genetic trait. [13] The volatile compound has been used as inhalation rodenticide and human poison, as well as for killing whales. [14] Cyanide ions interfere with iron-containing respiratory enzymes.[ citation needed ]

Chemical properties

Hydrogen cyanide is weakly acidic with a pKa of 9.2. It partially ionizes in water to give the cyanide anion, CN. HCN forms hydrogen bonds with its conjugate base, species such as (CN-)(HCN)n. [15]

Hydrogen cyanide reacts with alkenes to give nitriles. The conversion, which is called hydrocyanation, employs nickel complexes as catalysts. [16]


Four molecules of HCN will tetramerize into diaminomaleonitrile. [17]

Metal cyanides are typically prepared by salt metathesis from alkali metal cyanide salts, but mercuric cyanide is formed from aqueous hydrogen cyanide: [18]

HgO + 2 HCN → Hg(CN)2 + H2O

History of discovery

Hydrogen cyanide was first isolated in 1752 by French chemist Pierre Macquer who converted Prussian blue to an iron oxide plus a volatile component and that these could be used to reconstitute it. [19] The new component was what is now known as hydrogen cyanide. It was subsequently prepared from Prussian blue by the Swedish chemist Carl Wilhelm Scheele in 1782, [20] and was eventually given the German name Blausäure (lit. "Blue acid") because of its acidic nature in water and its derivation from Prussian blue. In English, it became known popularly as prussic acid.

In 1787, the French chemist Claude Louis Berthollet showed that prussic acid did not contain oxygen, [21] an important contribution to acid theory, which had hitherto postulated that acids must contain oxygen [22] (hence the name of oxygen itself, which is derived from Greek elements that mean "acid-former" and are likewise calqued into German as Sauerstoff). In 1811, Joseph Louis Gay-Lussac prepared pure, liquified hydrogen cyanide. [23] In 1815, Gay-Lussac deduced Prussic acid's chemical formula. [24] The radical cyanide in hydrogen cyanide was given its name from cyan, not only an English word for a shade of blue but the Greek word for blue (Ancient Greek : κύανος), again owing to its derivation from Prussian blue.

Production and synthesis

The most important process is the Andrussow oxidation invented by Leonid Andrussow at IG Farben in which methane and ammonia react in the presence of oxygen at about 1,200 °C (2,190 °F) over a platinum catalyst: [25]

2 CH4 + 2 NH3 + 3 O2 → 2 HCN + 6 H2O

In 2006, between 500 million and 1 billion pounds (between 230,000 and 450,000 t) were produced in the US. [26] Hydrogen cyanide is produced in large quantities by several processes and is a recovered waste product from the manufacture of acrylonitrile. [11]

Of lesser importance is the Degussa process (BMA process) in which no oxygen is added and the energy must be transferred indirectly through the reactor wall: [27]

CH4 + NH3 → HCN + 3H2

This reaction is akin to steam reforming, the reaction of methane and water to give carbon monoxide and hydrogen.

In the Shawinigan Process, hydrocarbons, e.g. propane, are reacted with ammonia.

In the laboratory, small amounts of HCN are produced by the addition of acids to cyanide salts of alkali metals:

H+ + NaCN → HCN + Na+

This reaction is sometimes the basis of accidental poisonings because the acid converts a nonvolatile cyanide salt into the gaseous HCN.

Hydrogen cyanide could be obtained from potassium ferricyanide and acid:

6 H+ + [Fe(CN)6]3− → 6 HCN + Fe3+ [28] [29]

Historical methods of production

The large demand for cyanides for mining operations in the 1890s was met by George Thomas Beilby, who patented a method to produce hydrogen cyanide by passing ammonia over glowing coal in 1892. This method was used until Hamilton Castner in 1894 developed a synthesis starting from coal, ammonia, and sodium yielding sodium cyanide, which reacts with acid to form gaseous HCN.


HCN is the precursor to sodium cyanide and potassium cyanide, which are used mainly in gold and silver mining and for the electroplating of those metals. Via the intermediacy of cyanohydrins, a variety of useful organic compounds are prepared from HCN including the monomer methyl methacrylate, from acetone, the amino acid methionine, via the Strecker synthesis, and the chelating agents EDTA and NTA. Via the hydrocyanation process, HCN is added to butadiene to give adiponitrile, a precursor to Nylon-6,6. [11]

HCN is used globally as a fumigant against many species of pest insects that infest food production facilities. Both its efficacy and method of application lead to very small amounts of the fumigant being used compared to other toxic substances used for the same purpose. [30] Using HCN as a fumigant also has less environmental impact, compared to some other fumigants such as sulfuryl fluoride, [31] and methyl bromide. [32]


HCN is obtainable from fruits that have a pit, such as cherries, apricots, apples, and bitter almonds, from which almond oil and flavoring are made. Many of these pits contain small amounts of cyanohydrins such as mandelonitrile and amygdalin, which slowly release hydrogen cyanide. [33] [34] One hundred grams of crushed apple seeds can yield about 70 mg of HCN. [35] So-called "bitter" roots of the cassava plant may contain up to 1 gram of HCN per kilogram. [36] [37] Some millipedes, such as Harpaphe haydeniana , Desmoxytes purpurosea , and Apheloria release hydrogen cyanide as a defense mechanism, [38] as do certain insects, such as burnet moths and the larvae of Paropsisterna eucalyptus . [39] Hydrogen cyanide is contained in the exhaust of vehicles, and in smoke from burning nitrogen-containing plastics.

The South Pole Vortex of Saturn's moon Titan is a giant swirling cloud of HCN (November 29, 2012) PIA18431-SaturnMoon-Titan-SouthPoleVortex-Cloud-20121129.jpg
The South Pole Vortex of Saturn's moon Titan is a giant swirling cloud of HCN (November 29, 2012)

On Titan

HCN has been measured in Titan's atmosphere by four instruments on the Cassini space probe, one instrument on Voyager, and one instrument on Earth. [40] One of these measurements was in situ, where the Cassini spacecraft dipped between 1,000 and 1,100 km (620 and 680 mi) above Titan's surface to collect atmospheric gas for mass spectrometry analysis. [41] HCN initially forms in Titan's atmosphere through the reaction of photochemically produced methane and nitrogen radicals which proceed through the H2CN intermediate, e.g., (CH3 + N → H2CN + H → HCN + H2). [42] [43] Ultraviolet radiation breaks HCN up into CN + H; however, CN is efficiently recycled back into HCN via the reaction CN + CH4 → HCN + CH3. [42]

On the young Earth

It has been postulated that carbon from a cascade of asteroids (known as the Late Heavy Bombardment), resulting from interaction of Jupiter and Saturn, blasted the surface of young Earth and reacted with nitrogen in Earth's atmosphere to form HCN. [44]

In mammals

Some authors[ who? ] have shown that neurons can produce hydrogen cyanide upon activation of their opioid receptors by endogenous or exogenous opioids. They have also shown that neuronal production of HCN activates NMDA receptors and plays a role in signal transduction between neuronal cells (neurotransmission). Moreover, increased endogenous neuronal HCN production under opioids was seemingly needed for adequate opioid analgesia, as analgesic action of opioids was attenuated by HCN scavengers. They considered endogenous HCN to be a neuromodulator. [45]

It has also been shown that, while stimulating muscarinic cholinergic receptors in cultured pheochromocytoma cells increases HCN production, in a living organism (in vivo) muscarinic cholinergic stimulation actually decreases HCN production. [46]

Leukocytes generate HCN during phagocytosis, and can kill bacteria, fungi, and other pathogens by generating several different toxic chemicals, one of which is hydrogen cyanide. [45]

The vasodilatation caused by sodium nitroprusside has been shown to be mediated not only by NO generation, but also by endogenous cyanide generation, which adds not only toxicity, but also some additional antihypertensive efficacy compared to nitroglycerine and other non-cyanogenic nitrates which do not cause blood cyanide levels to rise. [47]

HCN is a constituent of tobacco smoke. [48]

HCN and the origin of life

Hydrogen cyanide has been discussed as a precursor to amino acids and nucleic acids, and is proposed to have played a part in the origin of life. [49] Although the relationship of these chemical reactions to the origin of life theory remains speculative, studies in this area have led to discoveries of new pathways to organic compounds derived from the condensation of HCN (e.g. Adenine). [50]

In space

HCN has been detected in the interstellar medium [51] and in the atmospheres of carbon stars. [52] Since then, extensive studies have probed formation and destruction pathways of HCN in various environments and examined its use as a tracer for a variety of astronomical species and processes. HCN can be observed from ground-based telescopes through a number of atmospheric windows. [53] The J=1→0, J=3→2, J= 4→3, and J=10→9 pure rotational transitions have all been observed. [51] [54] [55]

HCN is formed in interstellar clouds through one of two major pathways: [56] via a neutral-neutral reaction (CH2 + N → HCN + H) and via dissociative recombination (HCNH+ + e → HCN + H). The dissociative recombination pathway is dominant by 30%; however, the HCNH+ must be in its linear form. Dissociative recombination with its structural isomer, H2NC+, exclusively produces hydrogen isocyanide (HNC).

HCN is destroyed in interstellar clouds through a number of mechanisms depending on the location in the cloud. [56] In photon-dominated regions (PDRs), photodissociation dominates, producing CN (HCN + ν → CN + H). At further depths, photodissociation by cosmic rays dominate, producing CN (HCN + cr → CN + H). In the dark core, two competing mechanisms destroy it, forming HCN+ and HCNH+ (HCN + H+ → HCN+ + H; HCN + HCO+ → HCNH+ + CO). The reaction with HCO+ dominates by a factor of ~3.5. HCN has been used to analyze a variety of species and processes in the interstellar medium. It has been suggested as a tracer for dense molecular gas [57] [58] and as a tracer of stellar inflow in high-mass star-forming regions. [59] Further, the HNC/HCN ratio has been shown to be an excellent method for distinguishing between PDRs and X-ray-dominated regions (XDRs). [60]

On 11 August 2014, astronomers released studies, using the Atacama Large Millimeter/Submillimeter Array (ALMA) for the first time, that detailed the distribution of HCN, HNC, H2CO, and dust inside the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON). [61] [62]

In February 2016, it was announced that traces of hydrogen cyanide were found in the atmosphere of the hot Super-Earth 55 Cancri e with NASA's Hubble Space Telescope. [63]

On 14 December 2023, astronomers reported the first time discovery, in the plumes of Enceladus, moon of the planet Saturn, of hydrogen cyanide, a possible chemical essential for life [64] as we know it, as well as other organic molecules, some of which are yet to be better identified and understood. According to the researchers, "these [newly discovered] compounds could potentially support extant microbial communities or drive complex organic synthesis leading to the origin of life." [65] [66]

As a poison and chemical weapon

In World War I, hydrogen cyanide was used by the French from 1916 as a chemical weapon against the Central Powers, and by the United States and Italy in 1918. It was not found to be effective enough due to weather conditions. [67] [68] The gas is lighter than air and rapidly disperses up into the atmosphere. Rapid dilution made its use in the field impractical. In contrast, denser agents such as phosgene or chlorine tended to remain at ground level and sank into the trenches of the Western Front's battlefields. Compared to such agents, hydrogen cyanide had to be present in higher concentrations in order to be fatal.

A hydrogen cyanide concentration of 100–200 ppm in breathing air will kill a human within 10 to 60 minutes. [69] A hydrogen cyanide concentration of 2000 ppm (about 2380 mg/m3) will kill a human in about one minute. [69] The toxic effect is caused by the action of the cyanide ion, which halts cellular respiration. It acts as a non-competitive inhibitor for an enzyme in mitochondria called cytochrome c oxidase. As such, hydrogen cyanide is commonly listed among chemical weapons as a blood agent. [70]

The Chemical Weapons Convention lists it under Schedule 3 as a potential weapon which has large-scale industrial uses. Signatory countries must declare manufacturing plants that produce more than 30 metric tons per year, and allow inspection by the Organisation for the Prohibition of Chemical Weapons.

Perhaps its most infamous use is Zyklon B (German: Cyclone B, with the B standing for Blausäure – prussic acid; also, to distinguish it from an earlier product later known as Zyklon A), [71] used in Nazi German extermination camps during World War II to kill Jews and other persecuted minorities en masse as part of their Final Solution genocide program. Hydrogen cyanide was also used in the camps for delousing clothing in attempts to eradicate diseases carried by lice and other parasites. One of the original Czech producers continued making Zyklon B under the trademark "Uragan D2" [72] until around 2015. [73]

During World War II, the US considered using it, along with cyanogen chloride, as part of Operation Downfall, the planned invasion of Japan, but President Harry Truman decided against it, instead using the atomic bombs developed by the secret Manhattan Project. [74]

Hydrogen cyanide was also the agent employed in judicial execution in some U.S. states, where it was produced during the execution by the action of sulfuric acid on sodium or potassium cyanide. [75]

Under the name prussic acid, HCN has been used as a killing agent in whaling harpoons, although it proved quite dangerous to the crew deploying it, and it was quickly abandoned. [14] From the middle of the 18th century it was used in a number of poisoning murders and suicides. [76]

Hydrogen cyanide gas in air is explosive at concentrations above 5.6%. [77]

Related Research Articles

<span class="mw-page-title-main">Cyanide</span> Any molecule with a cyano group (–C≡N)

In chemistry, a cyanide is a chemical compound that contains a C≡N functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom.

<span class="mw-page-title-main">Miller–Urey experiment</span> Experiment testing the origin of life

The Miller–Urey experiment (or Miller experiment) was an experiment in chemical synthesis carried out in 1952 that simulated the conditions thought at the time to be present in the atmosphere of the early, prebiotic Earth. It is seen as one of the first successful experiments demonstrating the synthesis of organic compounds from inorganic constituents in an origin of life scenario. The experiment used methane (CH4), ammonia (NH3), hydrogen (H2), in ratio 2:2:1, and water (H2O). Applying an electric arc (the latter simulating lightning) resulted in the production of amino acids.

<span class="mw-page-title-main">Organic compound</span> Carbon-containing chemical compound

Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-containing compounds such as alkanes and its derivatives are universally considered organic, but many others are sometimes considered inorganic, such as halides of carbon without carbon-hydrogen and carbon-carbon bonds, and certain compounds of carbon with nitrogen and oxygen.

<span class="mw-page-title-main">Potassium ferrocyanide</span> Chemical compound

Potassium ferrocyanide is the inorganic compound with formula K4[Fe(CN)6]·3H2O. It is the potassium salt of the coordination complex [Fe(CN)6]4−. This salt forms lemon-yellow monoclinic crystals.

<span class="mw-page-title-main">Sodium cyanide</span> Chemical compound

Sodium cyanide is a poisonous compound with the formula NaCN. It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also exploits its high reactivity toward metals. It is a moderately strong base.

<span class="mw-page-title-main">Astrochemistry</span> Study of molecules in the Universe and their reactions

Astrochemistry is the study of the abundance and reactions of molecules in the universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar System and the interstellar medium. The study of the abundance of elements and isotope ratios in Solar System objects, such as meteorites, is also called cosmochemistry, while the study of interstellar atoms and molecules and their interaction with radiation is sometimes called molecular astrophysics. The formation, atomic and chemical composition, evolution and fate of molecular gas clouds is of special interest, because it is from these clouds that solar systems form.

<span class="mw-page-title-main">Potassium ferricyanide</span> Chemical compound

Potassium ferricyanide is the chemical compound with the formula K3[Fe(CN)6]. This bright red salt contains the octahedrally coordinated [Fe(CN)6]3− ion. It is soluble in water and its solution shows some green-yellow fluorescence. It was discovered in 1822 by Leopold Gmelin.

In organic chemistry, a nitrile is any organic compound that has a −C≡N functional group. The name of the compound is composed of a base, which includes the carbon of the −C≡N, suffixed with "nitrile", so for example CH3CH2C≡N is called "propionitrile". The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons.

Benzonitrile is the chemical compound with the formula C6H5(CN), abbreviated PhCN. This aromatic organic compound is a colorless liquid with a sweet bitter almond odour. It is mainly used as a precursor to the resin benzoguanamine.

<span class="mw-page-title-main">Glycolaldehyde</span> Organic compound (HOCH2−CHO)

Glycolaldehyde is the organic compound with the formula HOCH2−CHO. It is the smallest possible molecule that contains both an aldehyde group and a hydroxyl group. It is a highly reactive molecule that occurs both in the biosphere and in the interstellar medium. It is normally supplied as a white solid. Although it conforms to the general formula for carbohydrates, Cn(H2O)n, it is not generally considered to be a saccharide.

<span class="mw-page-title-main">PAH world hypothesis</span> Hypothesis about the origin of life

The PAH world hypothesis is a speculative hypothesis that proposes that polycyclic aromatic hydrocarbons (PAHs), known to be abundant in the universe, including in comets, and assumed to be abundant in the primordial soup of the early Earth, played a major role in the origin of life by mediating the synthesis of RNA molecules, leading into the RNA world. However, as yet, the hypothesis is untested.

Hydrogen isocyanide is a chemical with the molecular formula HNC. It is a minor tautomer of hydrogen cyanide (HCN). Its importance in the field of astrochemistry is linked to its ubiquity in the interstellar medium.

<span class="mw-page-title-main">Protonated hydrogen cyanide</span> Chemical compound

HCNH+, also known as protonated hydrogen cyanide, is a molecular ion of astrophysical interest. It also exists in the condensed state when formed by superacids.

<span class="mw-page-title-main">Cyano radical</span> Chemical compound

The cyano radical (or cyanido radical) is a radical with molecular formula CN, sometimes written CN. The cyano radical was one of the first detected molecules in the interstellar medium, in 1938. Its detection and analysis was influential in astrochemistry. The discovery was confirmed with a coudé spectrograph, which was made famous and credible due to this detection. ·CN has been observed in both diffuse clouds and dense clouds. Usually, CN is detected in regions with hydrogen cyanide, hydrogen isocyanide, and HCNH+, since it is involved in the creation and destruction of these species (see also Cyanogen).

<span class="mw-page-title-main">Calcium cyanide</span> Chemical compound

Calcium cyanide is the inorganic compound with the formula Ca(CN)2. It is the calcium salt derived from hydrocyanic acid. It is a white solid, although the pure material is rarely encountered. It hydrolyses readily (even in moist air) to release hydrogen cyanide and is very toxic.

<span class="mw-page-title-main">Lithium cyanide</span> Toxic crystalline salt

Lithium cyanide is an inorganic compound with the chemical formula LiCN. It is a toxic, white coloured, hygroscopic, water-soluble salt that finds only niche uses.

<span class="mw-page-title-main">Diaminomaleonitrile</span> Chemical compound

Diaminomaleonitrile (DAMN) is an organic compound composed of two amino groups and two nitrile groups bonded to a central alkene unit. The systematic name reflects its relationship to maleic acid. DAMN form by oligomerization of hydrogen cyanide. It is the starting point for the synthesis of several classes of heterocyclic compounds. It has been considered as a possible organic chemical present in prebiotic conditions.

<span class="mw-page-title-main">Formyl cyanide</span> Organic compound (HC(O)C≡N)

Formyl cyanide is a simple organic compound with the formula HCOCN and structure HC(=O)−C≡N. It is simultaneously a nitrile and an aldehyde. Formyl cyanide is the simplest member of the acyl cyanide family. It is known to occur in space in the Sgr B2 molecular cloud.

<span class="mw-page-title-main">Prebiotic atmosphere</span>

The prebiotic atmosphere is the second atmosphere present on Earth before today's biotic, oxygen-rich third atmosphere, and after the first atmosphere of Earth's formation. The formation of the Earth, roughly 4.5 billion years ago, involved multiple collisions and coalescence of planetary embryos. This was followed by a <100 million year period on Earth where a magma ocean was present, the atmosphere was mainly steam, and surface temperatures reached up to 8,000 K (14,000 °F). Earth's surface then cooled and the atmosphere stabilized, establishing the prebiotic atmosphere. The environmental conditions during this time period were quite different from today: the Sun was ~30% dimmer overall yet brighter at ultraviolet and x-ray wavelengths, there was a liquid ocean, it is unknown if there were continents but oceanic islands were likely, Earth's interior chemistry was different, and there was a larger flux of impactors hitting Earth's surface.


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