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Chemical Name:
HCN;Blausure;prussic acid;formonitrile;methanenitrile;Formic nitrile;HYDROGEN CYANIDE;Hydrocyanic acid;LELOWRISYMNNSU-UHFFFAOYSA-N;hydrogen cyanide hydrocyanic acid
Molecular Formula:
Formula Weight:
MOL File:


Melting point:
Boiling point:
bp 25.6°
d(gas) 0.941 (air = 1); d(liq) 0.687
vapor pressure 
750 mmHg at 25 °C
refractive index 
colorless liquid
9.2(at 25℃)
Bitter almond odor detectable at 1 to 5 ppm; however, 20 to 60% of the population are reported to be unable to detect the odor of HCN
Water Solubility 
miscible with H2O, alcohol; slightly soluble ether [MER06]


Hazard Codes  F+,T+,N
Risk Statements  12-26-50/53-26/27/28
Safety Statements  7/9-16-36/37-38-45-60-61
RIDADR  1051
Autoignition Temperature 538 °C
HazardClass  6.1(a)
PackingGroup  I
Toxicity 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)


Manufacturer Product number Product description CAS number Packaging Price Updated Buy

HYDROGEN CYANIDE Chemical Properties,Uses,Production

Chemical Properties

Water-white liquid at temperatures below 26.5C; faint odor of bitter almonds. Usual commercial material is 96–99% pure.Soluble in water. The solution is weakly acidic, sensitive to light. When not absolutely pure or stabilized, hydrogen cyanide polymerize

Chemical Properties

HCN is a colorless to pale blue liquid or gas. It has a distinct odor resembling bitter almonds. HCN reacts with amines, oxidizers, acids, sodium hydroxide, calcium hydroxide, sodium carbonate, caustic substances, and ammonia. HCN was fi rst isolated from a blue dye, Prussian blue, in 1704. HCN is obtainable from fruits that have a pit, such as cherries, apricots, and bitter almonds, from which almond oil and fl avoring are made. HCN is used in fumigating, electroplating, mining, and in producing synthetic fi bers, plastics, dyes, and pesticides. It is also used as an intermediate in chemical syntheses. Exposures to cyanide occur in workplaces such as the electroplating, metallurgical, fi refi ghting, steel manufacturing, and metal cleaning industries. Human exposures to cyanide also occur from wastewater discharges of industrial organic chemicals, iron and steel works, and wastewater treatment facilities

Chemical Properties

Hydrocyanic acid (hydrogen cyanide) is a clear colorless liquid with a faint odor of bitter almonds. It evaporates easily (or boils) at room temperature and the vapors are slightly lighter than air. It is soluble in water. It is reactive and incompatible with amines, oxi- dizers, acids, sodium hydroxide, calcium hydroxide, sodium carbonate, caustics, and ammonia. Hydrogen cyanide is manufactured by the oxidation of ammonia–methane mixtures under controlled conditions and by the catalytic decomposition of formamide. It may be generated by treating cyanide salts with acid, and it is a combustion by-product of nitrogen-containing materials such as wool, silk, and plastics. It is also produced by enzy- matic hydrolysis of nitriles and related chemicals. Hydrogen cyanide gas is a by-product of coke-oven and blast furnace operations. Industrial applications of hydrogen cyanide are many. For instance, in fumigation, electroplating, mining, metallurgical, fi refi ghting, steel manufacturing, and metal cleaning industries, to producing synthetic fi bers, plastics, dyes, pesticides, and also as an intermediate in chemical syntheses.


ChEBI: A one-carbon compound consisting of a methine group triple bonded to a nitrogen atom. Also known as formonitrile, hydrogencyanide and prussic acid,HCN is a highly toxic liquid that has the odor of bitter almonds and boils at 25.6 °C.
also known as hydrocyanic acid, prussic acid, and fonnonitrile, is a very poisonous colorless gas with a characteristic fragrance of bitter almonds. Small amounts of hydrogen cyanide derivatives in combination with glucose and benzaldehyde are found in nature in apricot,peach,cherry, and plum pits.It liquifies at 26°C (79 OF) and is soluble in water,alcohol,and ether. Hydrogen cyanide is usually sold commercially as an aqueous solution containing 2 to 10% hydrogen cyanide. HCN reacts with amines, oxidisers, acids, sodium hydroxide, calcium hydroxide, sodium carbonate, caustic substances, and ammonia. The aqueous solutions of hydrogen cyani dedecompose slowly to form anunonium formate. In some uses, it is preferable to generate hydrogen cyanide as needed, thus eliminating handling and storage problems. 


HCN was first isolated from a blue dye, Prussian blue, in 1704. HCN is obtainable from fruits that have a pit, such as cherries, apricots, and bitter almonds, from which almond oil and flavouring are made. HCN is used in fumigating, electroplating, mining, and producing synthetic fibres, plastics, dyes, and pesticides. It also is used as an intermediate in chemical syntheses.
Besides, hydrogen cyanide is used in manufacturing cyanide salts, aerylonitrile,and dyes.It is also used as a horticultural fumigant.

General Description

Hydrocyanic acid solution is water containing up to 5% dissolved hydrocyanic acid with the faint odor of almonds. HYDROGEN CYANIDE is toxic by inhalation and skin absorption. Prolonged exposure to low concentrations or short term exposure to high concentrations may result in adverse health effects. Its vapors are just barely lighter than air.

Reactivity Profile

This particular record contains hydrogen cyanide dissolved in water. Hydrogen cyanide is a very volatile liquid or colorless gas smelling of bitter almonds, b.p. 26° C. A deadly human poison by all routes. The gas (hydrogen cyanide) forms explosive mixtures with air, HYDROGEN CYANIDE reacts violently with acetaldehyde. HYDROGEN CYANIDE is a severe explosion hazard when heated or exposed to oxidizers. HYDROGEN CYANIDE may polymerize explosively at elevated temperature (50-60° C) or in the presence of traces of alkali [Wohler, L. et al., Chem. Ztg., 1926, 50, p. 761, 781]. In the absence of a stabilizer (e.g., phosphoric acid) HYDROGEN CYANIDE may undergo explosively rapid spontaneous (autocatalytic) polymerization leading to a fire. The reaction is autocatalytic because of ammonia formation. The anhydrous acid should be stabilized by the addition of acid. [Bond, J., Loss Prev. Bull., 1991, 101, p.3]. During the preparation of imidoester hydrochlorides, hydrogen chloride was rapidly passed over alcoholic hydrogen cyanide. An explosion ensued, even with cooling of the process, [J. Org. Chem., 1955, 20, 1573].


Flammable, dangerous fire risk, explosive limits in air 6–41%. Toxic by ingestion, inhalation, and skin absorption. TLV: ceiling 4.7 ppm.

Health Hazard

The acute toxicity of hydrogen cyanide is high, and exposure by inhalation, ingestion, or eye or skin contact can be rapidly fatal. Symptoms observed at low levels of exposure (e.g., inhalation of 18 to 36 ppm for several hours) include weakness, headache, confusion, nausea, and vomiting. Inhalation of 270 ppm can cause immediate death, and 100 to 200 ppm can be fatal in 30 to 60 min. Aqueous solutions of HCN are readily absorbed through the skin and eyes, and absorption of 50 mg can be fatal. In humans, ingestion of 50 to 100 mg of HCN can be fatal. Because there is wide variation in the ability of different individuals to detect the odor of HCN, this substance is regarded as having poor warning properties. Effects of chronic exposure to hydrogen cyanide are nonspecific and rare

Health Hazard

TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

Health Hazard

Exposures to hydrogen cyanide cause adverse health effects to animals and humans. Hydrogen cyanide is readily absorbed from the lungs and the symptoms of poisoning begin within seconds to minutes. The symptoms of toxicity and poisoning include, but are not restricted to, asphyxia, lassitude or weakness, exhaustion, headache, confusion, nausea, vomiting, increased rate and depth of respiration, or respiration slow and gasp- ing, thyroid and blood changes. Inhalation of hydrogen cyanide causes headache, dizzi- ness, confusion, nausea, shortness of breath, convulsions, vomiting, weakness, anxiety, irregular heart beat, tightness in the chest, and unconsciousness, and these effects may be delayed. The target organs of induced toxicity and poisoning include the CNS, cardiovas- cular system, thyroid, and blood.

Health Hazard

HCN is particularly dangerous because of its toxic and asphyxiating effects on all life requiring oxygen to survive. HCN combines with the enzymes in tissue associated with cellular oxidation. The signs and symptoms of HCN poisoning are non-specifi c and very rapid. The symptoms include excitement, dizziness, nausea, vomiting, headache, weakness, drowsiness, gasping, thyroid, blood changes, confusion, fainting, tetanic spasm, lockjaw, convulsions, hallucinations, loss of consciousness, coma, and death. When oxygen becomes unavailable to the tissues, it leads to asphyxia and causes death. Children are more vulnerable to HCN exposure. HCN is readily absorbed from the lungs; symptoms of poisoning begin within seconds to minutes. Inhalation of HCN results in the rapid onset of poisoning, producing almost immediate collapse, respiratory arrest, and death within minutes (Table 1)

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

Fire Hazard

Hydrogen cyanide is a highly flammable liquid. Liquid HCN contains a stabilizer (usually phosphoric acid), and old samples may explode if the acid stabilizer is not maintained at a sufficient concentration.


Hydrogen cyanide should be stored in a cool, dry, well-ventilated area in tightly sealed containers and with the correct label. Containers of hydrogen cyanide should be protected from physical damage and should be stored separately from amines and oxidizers, such as perchlorates, peroxides, permanganates, chlorates, and nitrates. It should be kept sepa- rated from strong acids, such as hydrochloric, sulfuric, and nitric acids, away from sodium hydroxide, calcium hydroxide, sodium carbonate, water, ammonia, acetaldehyde, and caustics.

Purification Methods

HCN is prepared from NaCN and H2SO4, and dried by passage through H2SO4 and over CaCl2, then distilled in a vacuum system and degassed at 77oK before use [Arnold & Smith J Chem Soc, Faraday Trans 2 77 861 1981]. Cylinder HCN may contain stabilisers against explosive polymerisation, together with small amounts of H3PO4, H2SO4, SO2, and water. It can be purified by distillaton over P2O5, then frozen in Pyrex bottles at Dry-ice temperature for storage. [Zeigler Org Synth Coll Vol I 314 1941, Glemser in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I pp 658-660 1963.] Liquid HCN, like liquid ammonia, evaporates very slowly since the latent heat of evaporation is high and keeps it in the liquid state because the temperature of the liquid is lowered to below its boiling point. EXTREMELY POISONOUS; all due precautions should be taken.


HCN can polymerize explosively if heated above 50 °C or in the presence of trace amounts of alkali.

Flammability and Explosibility

Hydrogen cyanide is a highly flammable liquid. Liquid HCN contains a stabilizer (usually phosphoric acid), and old samples may explode if the acid stabilizer is not maintained at a sufficient concentration.

Waste Disposal

In the event of a spill, remove all ignition sources. Cleanup should be conducted wearing appropriate chemical-resistant clothing and respiratory protection Disposal Excess hydrogen cyanide and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines. For more information on disposal procedures, see Chapter 7 of this volume.


Occupational workers should be very careful in the management of HCN since the gas in air is explosive at concentrations over 5.6%, equivalent to 56,000 ppm and it does not provide adequate warning of hazardous concentrations. HCN at a concentration of 300 mg/m3 in air becomes fatal within about 10 min and HCN at a concentration of 3500 ppm (about 3200 mg/m3 ) kills a human in about 1 min.

HYDROGEN CYANIDE Preparation Products And Raw materials

Raw materials

Preparation Products


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