Hydrogen cyanide is called hydrocyanic or hydrocyanic acid. It is colorless, highly volatile and mobile, highly flammable, and has a characteristic almond odor. Extremely poisonous.
Properties
Hydrogen cyanide (formula HCN) is found in nature, it is accumulated by some plants, its share is also in the smoke of tobacco, coke, release is observed during the thermal decomposition of polyurethanes and nylon. This substance is a natural insecticide and protects the bones and seeds of many plants from pests. For example, it is found in the kernels of apricots, plums, cherries, almonds.
Easily mixes at any ratio with diethyl alcohol, ethanol and water, aldehyde also reacts with it. Hydrogen cyanide becomes solid at -13.3 degrees Celsius, the structure of ice is fibrous. Turns into gas at +25.7 degrees. The gas is lighter than air.
Different materials easily absorb hydrocyanic acid. These are, for example, rubber, fabrics, concrete, bricks, as well as any food products. Hydrogen cyanide mixed with air forms a flammable, explosive mixture, the explosion force of which is greater than from TNT.
Use
Hydrocyanic acid is used in the production of acrylonitrile,acrylates, which are subsequently used in the manufacture of plastics. It is also necessary for the production of cyanogen chloride, acrylonitrile, amino acids and fumigants used in agriculture to kill pests. Participates in the synthesis of nitrile rubbers and synthetic fibers, lactic acid and plexiglass. It is successfully used in the fight against rodents, for disinfection and destruction of pests of fruit trees.
Transportation and storage
For the transportation of hydrogen cyanide, cylinders and containers, railway tanks are used as temporary storage. For permanent storage, ground vertical cylindrical tanks with a volume of fifty to five thousand cubic meters (fill factor 0.9-0.95) are used. Atmospheric pressure, the temperature in the cylinders does not decrease. The maximum storage capacity is two tons.
Poison
Headache, irritation of the mucous membranes, a feeling of bitterness in the mouth, panic - all this can cause hydrogen cyanide. Exposure to a person begins after overcoming the threshold of 0.3 mg/m3 (cubed) - this is the maximum allowable concentration in the air for workplaces. The atmospheric air of settlements should not contain more than 0.01 mg/m3.
A person begins to smell the characteristic smell of almonds at a concentration of 2-5 mg/m3. With an increase in concentration to 5-20 mg/m3 the first symptoms appear: pain in the head and dizziness, irritation of the mucous membranes andeyes, bitterness is felt in the mouth, and an unreasonable feeling of fear also appears. Prolonged inhalation of vapors at a concentration of 50-60 mg/m3 causes nausea and vomiting, palpitations, dilated pupils, convulsions and loss of consciousness. For a fatal outcome, it is enough to inhale vapors with a concentration of 130 mg/m3 for an hour, and at a concentration of 220 mg/m3, the time is reduced to five minutes. The lethal concentration is 1500 mg/m3.
Physiological effects
Prussic acid is a substance that can cause oxygen starvation in tissues. In case of poisoning in the human body, an increase in the oxygen content in the venous and arterial blood is observed, thus the arterial-venous difference decreases, as a result, oxygen consumption by tissues decreases sharply. Hydrogen cyanide and its s alts, being dissolved in the blood, enter the tissues and react with cytochrome oxidase. After combining with cyanide, this ferric form of iron is disrupted by the function of transferring electrons to oxygen molecules. Due to the fact that the final oxidation link fails, the entire breathing process is disrupted, tissues suffer from hypoxia, because although oxygen is delivered in the right amount, it is not absorbed and is sent to the venous blood unchanged.
During hydrocyanic acid poisoning, glycolysis is activated: the metabolism changes from aerobic to anaerobic.
Troubleshooting
Hydrogen cyanide (hazard class - 2) can be deadlydangerous to humans. During the liquidation of accidents that are associated with the release or spill of NCH, the danger zone is 400 meters. It is necessary to isolate it and remove people, remove any sources of flame, and it is also forbidden to smoke. You should be on the leeward side.
When staying within the danger zone, it is mandatory to use protective equipment (insulating gas masks or breathing apparatus, as well as skin protection L-1, KIKH-5 and KIKH-4). Outside the four hundred meter zone, you can not use skin protection and get by with industrial and civilian gas masks to protect yourself from poisoning.
Gas masks and other protective equipment
Combined-arms filter gas masks are effective if the concentration of hydrogen cyanide in the air is less than 2500 mg/m3. Industrial filtering gas masks are used at a maximum allowable concentration of 6000 mg/m3. However, if the proportion of hydrocyanic acid vapor in the air is 7000-12000 mg / m 3 (7-12 g), then even wearing a gas mask, a person will feel the symptoms of poisoning in a few minutes due to penetration through the skin. That is why at high concentrations or during prolonged work in the accident zone, the use of full protective equipment is mandatory.
