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52-487: Sodium cyanide is produced by treating hydrogen cyanide with sodium hydroxide : Worldwide production was estimated at 500,000 tons in the year 2006. Formerly it was prepared by the Castner process involving the reaction of sodium amide with carbon at elevated temperatures. The structure of solid NaCN is related to that of sodium chloride . The anions and cations are each six-coordinate. Potassium cyanide (KCN) adopts

104-519: A defense mechanism, as do certain insects, such as burnet moths and the larvae of Paropsisterna eucalyptus . Hydrogen cyanide is contained in the exhaust of vehicles, and in smoke from burning nitrogen-containing plastics . 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. One of these measurements

156-488: 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 and as a tracer of stellar inflow in high-mass star-forming regions. Further, the HNC/HCN ratio has been shown to be an excellent method for distinguishing between PDRs and X-ray-dominated regions (XDRs). On 11 August 2014, astronomers released studies, using

208-488: A group evaporate (or sublimate in the case of solids) when exposed to the atmosphere. A highly volatile substance such as rubbing alcohol ( isopropyl alcohol ) will quickly evaporate, while a substance with low volatility such as vegetable oil will remain condensed. In general, solids are much less volatile than liquids, but there are some exceptions. Solids that sublimate (change directly from solid to vapor) such as dry ice (solid carbon dioxide ) or iodine can vaporize at

260-647: A living organism ( in vivo ) muscarinic cholinergic stimulation actually decreases HCN production. 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. 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. HCN

312-477: 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 . It has also been shown that, while stimulating muscarinic cholinergic receptors in cultured pheochromocytoma cells increases HCN production, in

364-454: 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 . In the case of hydrogen cyanide, the R group is hydrogen H, so the other names of hydrogen cyanide are methanenitrile and formonitrile. Hydrogen cyanide

416-428: A significant risk associated with cyanide salts. It is detoxified most efficiently with hydrogen peroxide ( H 2 O 2 ) to produce sodium cyanate (NaOCN) and water: Gold cyanidation (also known as the cyanide process) is the dominant technique for extracting gold , much of which is obtained from low-grade ore . More than 70% of cyanide consumption globally is used for this purpose. The application exploits

468-511: A significant role. The effect of molecular mass can be partially isolated by comparing chemicals of similar structure (i.e. esters, alkanes, etc.). For instance, linear alkanes exhibit decreasing volatility as the number of carbons in the chain increases. Knowledge of volatility is often useful in the separation of components from a mixture. When a mixture of condensed substances contains multiple substances with different levels of volatility, its temperature and pressure can be manipulated such that

520-434: A similar rate as some liquids under standard conditions. Volatility itself has no defined numerical value, but it is often described using vapor pressures or boiling points (for liquids). High vapor pressures indicate a high volatility, while high boiling points indicate low volatility. Vapor pressures and boiling points are often presented in tables and charts that can be used to compare chemicals of interest. Volatility data

572-488: A similar structure. When treated with acid , it forms the toxic gas hydrogen cyanide : Because the salt is derived from a weak acid, sodium cyanide readily reverts to HCN by hydrolysis ; the moist solid emits small amounts of hydrogen cyanide, which is thought to smell like bitter almonds (not everyone can smell it—the ability thereof is due to a genetic trait). Sodium cyanide reacts rapidly with strong acids to release hydrogen cyanide. This dangerous process represents

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624-430: A single step. Crude oil entering a refinery is composed of many useful chemicals that need to be separated. The crude oil flows into a distillation tower and is heated up, which allows the more volatile components such as butane and kerosene to vaporize. These vapors move up the tower and eventually come in contact with cold surfaces, which causes them to condense and be collected. The most volatile chemical condense at

676-419: A substance with high volatility is more likely to exist as a vapour , while a substance with low volatility is more likely to be a liquid or solid . Volatility can also describe the tendency of a vapor to condense into a liquid or solid; less volatile substances will more readily condense from a vapor than highly volatile ones. Differences in volatility can be observed by comparing how fast substances within

728-457: A temperature where most of the ethanol vaporizes while most of the water remains liquid. The ethanol vapor is then collected and condensed in a separate container, resulting in a much more concentrated product. Volatility is an important consideration when crafting perfumes . Humans detect odors when aromatic vapors come in contact with receptors in the nose. Ingredients that vaporize quickly after being applied will produce fragrant vapors for

780-491: 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. It

832-459: Is a linear molecule , with a triple bond between carbon and nitrogen . The tautomer of HCN is HNC, hydrogen isocyanide . HCN has a faint bitter almond -like odor that some people are unable to detect owing to a recessive genetic trait . The volatile compound has been used as inhalation rodenticide and human poison, as well as for killing whales. Cyanide ions interfere with iron-containing respiratory enzymes. Hydrogen cyanide

884-457: Is a constituent of tobacco smoke . 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 . 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 ). HCN has been detected in

936-548: Is among the most rapidly acting of all known poisons. NaCN is a potent inhibitor of respiration , acting on mitochondrial cytochrome oxidase and hence blocking electron transport. This results in decreased oxidative metabolism and oxygen utilization. Lactic acidosis then occurs as a consequence of anaerobic metabolism. An oral dosage as small as 200–300 mg can be fatal. Hydrogen cyanide 12.9 (in DMSO) Hydrogen cyanide (formerly known as prussic acid )

988-456: Is classified as a strong nucleophile , is used to prepare nitriles , which occur widely in many chemicals, including pharmaceuticals. Illustrative is the synthesis of benzyl cyanide by the reaction of benzyl chloride and sodium cyanide. Being highly toxic, sodium cyanide is used to kill or stun rapidly such as in collecting jars used by entomologists and in widely illegal cyanide fishing . Sodium cyanide, like other soluble cyanide salts,

1040-467: Is destroyed in interstellar clouds through a number of mechanisms depending on the location in the cloud. 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

1092-707: Is efficiently recycled back into HCN via the reaction CN + CH 4 → HCN + CH 3 . 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. Some authors 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

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1144-477: Is formed from aqueous hydrogen cyanide: 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 found that these could be used to reconstitute it. 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, and

1196-466: Is formed in interstellar clouds through one of two major pathways: via a neutral-neutral reaction (CH 2 + 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, H 2 NC , exclusively produces hydrogen isocyanide (HNC). HCN

1248-407: 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

1300-679: Is obtainable from fruits that have a pit , such as cherries , apricots , apples , and nuts such as bitter almonds , from which almond oil and extract is made. Many of these pits contain small amounts of cyanohydrins such as mandelonitrile and amygdalin , which slowly release hydrogen cyanide. One hundred grams of crushed apple seeds can yield about 70 mg of HCN. The roots of cassava plants contain cyanogenic glycosides such as linamarin , which decompose into HCN in yields of up to 370 mg per kilogram of fresh root. Some millipedes , such as Harpaphe haydeniana , Desmoxytes purpurosea , and Apheloria release hydrogen cyanide as

1352-414: Is typically found through experimentation over a range of temperatures and pressures. Vapor pressure is a measurement of how readily a condensed phase forms a vapor at a given temperature. A substance enclosed in a sealed vessel initially at vacuum (no air inside) will quickly fill any empty space with vapor. After the system reaches equilibrium and the rate of evaporation matches the rate of condensation,

1404-423: 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. Using HCN as a fumigant also has less environmental impact, compared to some other fumigants such as sulfuryl fluoride , and methyl bromide . HCN

1456-544: Is weakly acidic with a p K a 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 . Hydrogen cyanide reacts with alkenes to give nitriles. The conversion, which is called hydrocyanation , employs nickel complexes as catalysts. Four molecules of HCN will tetramerize into diaminomaleonitrile . Metal cyanides are typically prepared by salt metathesis from alkali metal cyanide salts, but mercuric cyanide

1508-547: The Atacama Large Millimeter/Submillimeter Array (ALMA) for the first time, that detailed the distribution of HCN, HNC , H 2 CO , and dust inside the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON) . 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 . On 14 December 2023, astronomers reported

1560-634: 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), 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

1612-480: 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 . HCN

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1664-460: The interstellar medium and in the atmospheres of carbon stars . 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. The J=1→0, J=3→2, J= 4→3, and J=10→9 pure rotational transitions have all been observed. HCN

1716-674: The origin of life ." 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. 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

1768-473: 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. A hydrogen cyanide concentration of 2000 ppm (about 2380 mg/m ) will kill a human in about one minute. The toxic effect is caused by

1820-461: 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

1872-550: The Greek word for blue ( Ancient Greek : κύανος ), again owing to its derivation from Prussian blue. 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: In 2006, between 500 million and 1 billion pounds (between 230,000 and 450,000 t) were produced in

1924-540: 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 : 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: The large demand for cyanides for mining operations in

1976-549: The US. Hydrogen cyanide is produced in large quantities by several processes and is a recovered waste product from the manufacture of acrylonitrile . 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: This reaction is akin to steam reforming , the reaction of methane and water to give carbon monoxide and hydrogen . In

2028-510: 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 . 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

2080-408: The atomic bombs developed by the secret Manhattan Project . 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 cyanide or potassium cyanide . Under the name prussic acid , HCN has been used as a killing agent in whaling harpoons, although it proved quite dangerous to

2132-402: The crew deploying it, and it was quickly abandoned. From the middle of the 18th century it was used in a number of poisoning murders and suicides. Hydrogen cyanide gas in air is explosive at concentrations above 5.6%. Volatility (chemistry) In chemistry , volatility is a material quality which describes how readily a substance vaporizes . At a given temperature and pressure ,

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2184-435: The first time discovery, in the plumes of Enceladus , moon of the planet Saturn , of hydrogen cyanide, a possible chemical essential for life 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

2236-557: The high affinity of gold(I) for cyanide, which induces gold metal to oxidize and dissolve in the presence of air (oxygen) and water, producing the salt sodium dicyanoaurate (or sodium gold cyanide) ( NaAu(CN) 2 ): A similar process uses potassium cyanide (KCN, a close relative of sodium cyanide) to produce potassium dicyanoaurate ( KAu(CN) 2 ). Several commercially significant chemical compounds are derived from cyanide, including cyanuric chloride , cyanogen chloride , and many nitriles . In organic synthesis , cyanide, which

2288-590: The liquid to rapidly evaporate, or boil. It is closely related to vapor pressure, but is dependent on pressure. The normal boiling point is the boiling point at atmospheric pressure, but it can also be reported at higher and lower pressures. An important factor influencing a substance's volatility is the strength of the interactions between its molecules. Attractive forces between molecules are what holds materials together, and materials with stronger intermolecular forces , such as most solids, are typically not very volatile. Ethanol and dimethyl ether , two chemicals with

2340-445: The more volatile components change to a vapor while the less volatile substances remain in the liquid or solid phase. The newly formed vapor can then be discarded or condensed into a separate container. When the vapors are collected, this process is known as distillation . The process of petroleum refinement utilizes a technique known as fractional distillation , which allows several chemicals of varying volatility to be separated in

2392-410: 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. In 1815, Gay-Lussac deduced Prussic acid's chemical formula. The radical cyanide in hydrogen cyanide was given its name from cyan , not only an English word for a shade of blue but

2444-585: The same formula (C 2 H 6 O), have different volatilities due to the different interactions that occur between their molecules in the liquid phase: ethanol molecules are capable of hydrogen bonding while dimethyl ether molecules are not. The result in an overall stronger attractive force between the ethanol molecules, making it the less volatile substance of the two. In general, volatility tends to decrease with increasing molecular mass because larger molecules can participate in more intermolecular bonding, although other factors such as structure and polarity play

2496-429: The top of the column while the least volatile chemicals to vaporize condense in the lowest portion. On the right is a picture illustrating the design of a distillation tower . The difference in volatility between water and ethanol has traditionally been used in the refinement of drinking alcohol . In order to increase the concentration of ethanol in the product, alcohol makers would heat the initial alcohol mixture to

2548-405: The vapor pressure can be measured. Increasing the temperature increases the amount of vapor that is formed and thus the vapor pressure. In a mixture, each substance contributes to the overall vapor pressure of the mixture, with more volatile compounds making a larger contribution. Boiling point is the temperature at which the vapor pressure of a liquid is equal to the surrounding pressure, causing

2600-579: 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. HCN initially forms in Titan's atmosphere through the reaction of photochemically produced methane and nitrogen radicals which proceed through the H 2 CN intermediate, e.g., (CH 3 + N → H 2 CN + H → HCN + H 2 ). Ultraviolet radiation breaks HCN up into CN + H; however, CN

2652-447: 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" until around 2015. 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

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2704-473: 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, an important contribution to acid theory, which had hitherto postulated that acids must contain oxygen (hence

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