Hydrogen cyanide is called hydrocyanic or hydrocyanic acid. It is colorless, very volatile and mobile, highly flammable, has a characteristic almond odor. Extremely poisonous.
The properties
Hydrogen cyanide (HCN formula) is found in nature, it is accumulated by some plants, its share is also in the smoke of tobacco, coke, emission 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.
It is easily mixed at any ratio with diethyl alcohol, ethanol and water, and the aldehyde also reacts with it. Hydrogen cyanide becomes solid at -13.3 degrees Celsius, the ice structure is fibrous. It turns into gas at +25.7 degrees. Gas is lighter than air.
Various materials readily absorb hydrocyanic acid. This, for example, rubber, fabrics, concrete, brick, as well as any food products. Hydrogen cyanide mixed with air forms a highly flammable, explosive mixture, the explosion force of which is greater than from TNT.
Using
Hydrocyanic acid is used in the manufacture of acrylonitrile, acrylates, which subsequently go into the manufacture of plastics. It is also necessary for the production of chlorocyan, acrylonitrile, amino acids and fumigants, which are 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 extermination of pests of fruit trees.
Transportation and storage
For transportation of hydrogen cyanide, cylinders and containers, railway tanks are used as temporary storage . For permanent storage, ground - based vertical cylindrical tanks with a volume of from fifty to five thousand cubic meters are used (fill factor 0.9-0.95). The pressure is atmospheric, 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 / m 3 (in the cube) - this is the maximum permissible concentration in the air for workrooms. The atmospheric air of settlements should not contain more than 0.01 mg / m 3 .
A person begins to feel the characteristic smell of almonds at a concentration of 2-5 mg / m 3 . With an increase in concentration to 5-20 mg / m 3, the first symptoms appear: headaches and dizziness, irritation of the mucous membranes and eyes, bitterness in the mouth, and an unreasonable feeling of fear. Prolonged inhalation of vapors with a concentration of 50-60 mg / m 3 causes nausea and vomiting, palpitations, dilated pupils, cramps and loss of consciousness. For death, it is enough to inhale vapors with a concentration of 130 mg / m 3 for an hour, and at a concentration of 220 mg / m 3 the time is reduced to five minutes. The lethal concentration is 1500 mg / m 3 .
Physiological effects
Hydrocyanic acid is a substance that can cause oxygen starvation in tissues. With poisoning in the human body, an increase in the oxygen content in the venous and arterial blood is observed, thus the arterial-venous difference is reduced, as a result, the oxygen consumption of the tissues decreases sharply. Hydrogen cyanide and its salts, when dissolved in the blood, enter the tissues and react with cytochrome oxidase. After combining with cyanide, this trivalent form of iron disrupts the electron transfer function to oxygen molecules. Due to the fact that the final oxidation link fails, the entire breathing process is disrupted, the 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: metabolism changes from aerobic to anaerobic.
Troubleshoot
Cyanide hydrogen (hazard class 2) can be deadly to humans. During the liquidation of accidents that are associated with the release or spill of the NCH, the danger zone is 400 meters. It is necessary to isolate it and remove people, remove any sources of flame, it is also forbidden to smoke. It should be on the leeward side.
When in the danger zone, the use of protective equipment (insulating gas masks or breathing apparatus, as well as skin protective equipment L-1, KIH-5 and KIH-4) is mandatory. Outside the four-hundred-meter zone, you can not use skin protection equipment and dispense with industrial and civilian gas masks in order to protect yourself from poisoning.
Gas masks and other protective equipment
Combined arms gas masks are effective if the concentration of hydrogen cyanide in the air is less than 2500 mg / m 3 . Industrial filter gas masks are used at the maximum permissible concentration of 6000 mg / m 3 . 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 in a few minutes will feel the symptoms of poisoning 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.