Cyanidehydrogen is a chemical compound with the formula HCN that is found in its pure state in gaseous form, or in liquid form also called hydrocyanic acid. Naturally produced by certain plants, it is found for example in high concentration in the nuclei ofapricot, of plum or from Cherry, bitter almond, cassava or sorghum root (unripe seeds). It is also present in tobacco smoke, exhaust gas and can form accidentally during chemical reactions between cyanide and an acid, or by the combustion of certain materials plastic (polyurethane, nylon) or wool.
Hydrogen cyanide is highly toxic to health and the environment, especially aquatic organisms. In gaseous form, it is colorless and is distinguished by its odor ofalmond bitter, the detection threshold of which differs greatly between individuals. It is an extremely flammable and explosive gas from a concentration of 5.5% in theair. Form liquid, it appears as a colorless slightly bluish liquid and very volatile.
Hydrogen cyanide: physical and chemical properties
- explosive limit in air: 5.5 to 41%
- point flash : -17.8 ° C
- auto-ignition temperature: 537 ° C
- boiling point: 27.5 ° C
- melting temperature: -13.3 ° C
- molecular weight: 27.03 g / mol
- density: 0.688 at 20 ° C
- vapor density (air = 1): 0.932
Hydrogen cyanide: uses
Hydrogen cyanide was used as a chemical weapon during WWII under the name Zylcon B and in gas chambers or for executions. It has been used in the past as a fumigant insecticide Where rodenticide, but this use was banned in the 1960s. It remains authorized in certain cases for disinfecting planes or boats, cleaning of woodwork precious or seed treatment. It is also used for electroplating, metallurgy, photographic development.
Hydrogen cyanide is used today mainly as an intermediate in the manufacture of chemicals:
- adiponitrile for nylon production
- methyl methacrylate for the production of acrylic plastic
- triazines used in herbicides
- methionine (amino acid used in animal feed)
- cyanides sodium and of potassium for the extraction and concentration of ores (gold and silver)
Hydrogen cyanide: health risks
Hydrogen cyanide is a very powerful poison which inhibits the process of oxygen transport and blocks the cellular respiration. Acute poisoning occurs within seconds or minutes by inhalation, ingestion or by contact with the skin. The lethal dose is estimated to be 1.5 mg / kg (liquid), 100 mg / kg (dermal exposure) and 546 ppm after 10 minutes (by inhalation).
Acute hydrogen cyanide poisoning leads to nervous system disorders with headache, confusion, weakness, dizziness, nausea, vomiting, panting, tremors, anxiety, palpitations, feeling of tightness, loss of consciousness, convulsions, paralysis, which can lead to respiratory arrest and death.
Chronic exposure to hydrogen cyanide causes headaches, irritation of eyes and pharynx, fatigue, shortness of breath on exertion, modification of the sense of smell and taste, increased volume of the thyroid.
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