Hydrogen cyanide

inorganic compound

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Hydrogen cyanide is an inorganic compound, chemical formula HCN, and it is liquid in standard state. Hydrogen cyanide is easy to be evenly dispersed in the air and can burn in the air. When the content of hydrogen cyanide in the air reaches 5.6%~12.8%, it is explosive. Hydrocyanic acid is highly toxic. The clinical manifestations of acute hydrogen cyanide poisoning are obvious bitter almond smell in the exhaled breath of the patient. Mild poisoning is mainly manifested by chest tightness, palpitations, rapid heart rate, headache, nausea, vomiting, and blurred vision. The main manifestations of severe poisoning are deep coma, shallow and fast breathing, paroxysmal convulsions, and even tonic convulsions. In World War II, Nazi Germany often used hydrogen cyanide as the killing gas in the gas chamber.

Chinese name: Hydrogen cyanide
Foreign name: hydrogen cyanide
Alias: Acrylonitrile
chemical formula: HCN
molecular weight: twenty-seven point zero three
CAS login number: 74-90-8
EINECS login number: 200-821-6
Melting point: -13.4 ℃
Boiling point: 26 ℃

Water solubility: soluble
Density: 0.69 g/cm³
Appearance: Colorless gas or liquid with bitter almond flavor
Flash point: -17.8 ℃
Application: Electroplating industry and mining industry
Security description: S16；S36/37；S38；S45
Hazard symbol: T+；N；F
Hazard description: R12；R23/24/25；R26
UN dangerous goods number: one thousand and fifty-one

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essential information

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Chemical formula: HCN

Molecular weight: 27.03

CAS No.: 74-90-8

EINECS No.: 200-821-6

Physical and chemical properties

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physical property

Density: 0.69g/cm three

Melting point: - 13.4 ℃

Boiling point: 26 ℃

Flash point: - 17.8 ℃

Saturated vapor pressure: 82.46kPa (20 ℃)

Critical pressure: 4.95MPa

Critical temperature: 183.5 ℃

LogP：-0.25

Refractive index: 1.531 (20 ℃)

Explosion limit: 5.6%~40% (volume)

Appearance: colorless transparent liquid, volatile, with bitter almond smell

Solubility: and ethanol 、 Ether 、 glycerol 、 ammonia 、 benzene 、 chloroform Miscible with water, etc.

chemical property

A weak acid reacts with a base to form a salt. When its aqueous solution boils, it is partially hydrolyzed to form a salt Ammonium formate 。 Under alkaline conditions aldehyde 、 ketone Combined to form cyanohydrin, and acetone Action generation Acetone cyanohydrin 。 Gaseous hydrogen cyanide generally does not produce polymerization, but when there is water condensation, polymerization will occur, and oxygen does not promote polymerization 。 Liquid hydrogen cyanide or its aqueous solution will cause polymerization under alkaline, high temperature, long-term storage, exposure to light and radiation, discharge and electrolysis conditions. After polymerization starts, the generated heat will cause the chain reaction of polymerization, thus accelerating the polymerization reaction. At the same time, a large amount of heat will be released, causing a violent explosion. The explosion limit is 5.6%~40% (volume). Its vapor burns in a blue flame. When there is hydrocyanic acid in the air, the reaction is blue as determined by benzidine copper acetate test paper, orange to pink as determined by methyl orange mercuric chloride (Ⅱ) test paper, and yellow to brown as determined by picric acid sodium carbonate test paper. Extremely toxic.

Chemical reaction equation:

As HCN is weaker than carbonic acid and stronger than bicarbonate, it cannot react with carbonate to release CO two , cyanide will absorb CO two And generate bicarbonate:

Molecular structure data

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Molar refractive index: 6.41

Molar volume (cm three /mol）：38.8

Isotonic specific volume (90.2K): 38.8

Surface tension (dyne/cm): 18.8

Polarization (10 -24 cm three ）：2.54

Calculate chemical data

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Drainage parameter calculation reference value (XlogP): 0.1

Number of hydrogen bond donors: 0

Number of hydrogen bond receptors: 1

Number of rotatable chemical bonds: 0

Number of tautomers: 2

Topological molecular polar surface area: 23.8

Number of heavy atoms: 2

Surface charge: 0

Complexity: 10

Number of isotope atoms: 0

Determine the number of atomic structure centers: 0

Number of uncertain atomic structure centers: 0

Determine the number of chemical bond structure centers: 0

Number of uncertain chemical bond structure centers: 0

Number of covalent bond units: 1

toxicology

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Toxicity test

number	toxicity type	test method	Test object	Dosage	Toxic effect
one	acute	Oral	human beings	570 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
two	acute	inhalation	Adult male	500 mg/m three /3M-C	Eye Toxicity - Pupil Enlargement Behavioral toxicity - coma Lung, chest or respiratory toxicity - respiratory suppression
three	acute	inhalation	human beings	120 mg/m three /1H	No lethal dose value other than that reported for detailed toxic and side effects
four	acute	inhalation	human beings	200 mg/m three /10M	Behavioral toxicity - general anesthesia Lung, chest or respiratory toxicity - dyspnea Gastrointestinal toxicity - nausea and vomiting
five	acute	inhalation	Adult male	400 mg/m three /2M	No lethal dose value other than that reported for detailed toxic and side effects
six	acute	subcutaneous injection	human beings	1 mg/kg	No lethal dose value other than that reported for detailed toxic and side effects
seven	acute	intravenous injection	Adult male	55 μg/kg	Lung, chest or respiratory toxicity - respiratory tract irritation
eight	acute	Not reported	Adult male	1471 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
nine	acute	inhalation	Rat	160 ppm/30M	No lethal dose value other than that reported for detailed toxic and side effects
ten	acute	intravenous injection	Rat	810 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
eleven	acute	Oral	mice	3700 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twelve	acute	inhalation	mice	323 ppm/5M	No lethal dose value other than that reported for detailed toxic and side effects
thirteen	acute	intraperitoneal injection	mice	2990 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
fourteen	acute	subcutaneous injection	mice	3 mg/kg	No lethal dose value other than that reported for detailed toxic and side effects
fifteen	acute	intravenous injection	mice	990 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
sixteen	acute	intramuscular injection	mice	2700 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
seventeen	acute	Oral	dog	4 mg/kg	No lethal dose value other than that reported for detailed toxic and side effects
eighteen	acute	subcutaneous injection	dog	1700 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
nineteen	acute	intravenous injection	dog	1340 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twenty	acute	intravenous injection	monkey	1300 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twenty-one	acute	subcutaneous injection	cat	1100 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twenty-two	acute	intravenous injection	cat	810 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twenty-three	acute	Oral	rabbit	4 mg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twenty-four	acute	inhalation	rabbit	208 mg/m three /35M	Brain toxicity - other degenerative changes Cardiotoxicity - other changes Blood toxicity - other changes
twenty-five	acute	intraperitoneal injection	rabbit	1570 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twenty-six	acute	subcutaneous injection	rabbit	2500 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twenty-seven	acute	intravenous injection	rabbit	660 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twenty-eight	acute	intramuscular injection	rabbit	486 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
twenty-nine	acute	Ophthalmic injection	rabbit	1040 μg/kg	Eye toxicity - not reported Behavioral toxicity - ataxia Lung, chest or respiratory toxicity - respiratory tract irritation
thirty	acute	Oral	pig	2 mg/kg	No lethal dose value other than that reported for detailed toxic and side effects
thirty-one	acute	subcutaneous injection	guinea pig	100 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
thirty-two	acute	intravenous injection	guinea pig	1430 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
thirty-three	acute	Oral	dove	14 mg/kg	No lethal dose value other than that reported for detailed toxic and side effects
thirty-four	acute	subcutaneous injection	dove	2150 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
thirty-five	acute	intramuscular injection	dove	1500 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
thirty-six	acute	Oral	duck	3280 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
thirty-seven	acute	subcutaneous injection	frog	60 mg/kg	No lethal dose value other than that reported for detailed toxic and side effects
thirty-eight	acute	intravenous injection	Domestic mammals	660 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
thirty-nine	acute	inhalation	mammal	200 ppm/5M	No lethal dose value other than that reported for detailed toxic and side effects
forty	acute	inhalation	mammal	36 ppm/2H	No lethal dose value other than that reported for detailed toxic and side effects
forty-one	acute	Oral	Domestic poultry	600 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
forty-two	acute	Oral	Wild birds	7500 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
forty-three	acute	subcutaneous injection	Wild birds	100 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects
forty-four	acute	subcutaneous injection	Domestic poultry	100 μg/kg	No lethal dose value other than that reported for detailed toxic and side effects

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Toxicological data

The maximum allowable concentration is 0.3mg/m three 。 The lethal dose was 1mg/kg (body weight). Acute toxicity LC fifty ：357mg/m three (Inhalation in mice, 5min)

Cyanide ion can inhibit the activity of 42 enzymes in tissues and cells, such as Cytochrome oxidase 、 Peroxidase 、 decarboxylase 、 Succinate dehydrogenase and lactate dehydrogenase Etc. Among them, cytochrome oxidase is the most sensitive to cyanide. Cyanide ion can rapidly interact with Fe in oxidized cytochrome oxidase 3+ Combined to prevent its reduction to Fe 2+ , so that the oxidation process of electron transfer is interrupted, and the tissue cells can not use the oxygen in the blood to cause internal asphyxia. The central nervous system is most sensitive to hypoxia, so the brain is damaged first, leading to central respiratory failure and death. In addition, the hydrogen and oxygen ions released by cyanide in the digestive tract are corrosive. Those who inhale high concentration of hydrogen cyanide or swallow a large amount of cyanide can stop breathing within 2-3 minutes and die of "electric shock". Cyanide ion and Fe in blood 2+ Binding formation [Fe (CN) six ] 4- , reducing the ability of blood to transport oxygen by 6CN - + Fe 2+ = [Fe(CN) six ] 4- 。

Toxic effects: The harm of cyanide to human body can be divided into acute poisoning and chronic effects. The acute poisoning caused by cyanide can be divided into three grades: mild, moderate and severe. Mild poisoning is characterized by eye and upper respiratory tract irritation, bitter almond taste, numbness of lips and pharynx, and nausea, vomiting, tremor, etc; Moderate poisoning is characterized by sigh like breathing, skin and mucous membrane are often bright red, and other symptoms are aggravated; Severe poisoning is characterized by loss of consciousness, rigidity and paroxysmal convulsions, until the angle bow is reversed, blood pressure drops, urinary and fecal incontinence, often accompanied by brain edema and respiratory failure. The chronic effect of hydrocyanic acid on human body is manifested as neurasthenic syndrome, such as dizziness, headache, fatigue, chest compression, muscle pain, abdominal pain, etc., and may have eye and upper respiratory tract irritation symptoms. After long-term skin contact, it can cause skin rashes, which are characterized by spots, papules and extreme itching.

Concentration and leakage detection: the most common and accurate method is the "benzidine" method: prepare 0.1% benzidine acetate and 0.3% copper acetate solution, store them in brown bottles respectively, and mix one part of each solution before use (use within 15 minutes). Cut the filter paper into 6cm × 12cm strips to absorb the liquid medicine. The strips with the liquid medicine are blue when encountering cyanic acid gas.

Ventilation, poison dispersal and residue treatment: after the sealing time is reached, open the air window of the warehouse to allow the indoor poison gas to escape. Personnel can enter the fumigation site until it is tested to be non-toxic. After the poison dispersal, lift the reaction tank to a place far away from the warehouse and dig a pit for deep burial. The burial point should also be more than 50 m away from the riverside well.

Poisoning symptoms

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Mild poisoning

Irritation symptoms of eyes and upper respiratory tract, headache, dizziness, chest tightness, nausea, weakness, etc., bitter almond smell in the exhaled breath, which can be relieved by itself.

Moderate poisoning

Nausea, vomiting, chest compression, shortness of breath, bright red or pale skin and mucosa.

Severe poisoning

It causes water accumulation in the brain, nerve compression, loss of consciousness, fatigue, tetanic or paroxysmal convulsions, muscle relaxation in the whole body, loss of reflexes, and breathing and heartbeat can stop at any time.

First aid measures

Move the patient to a place with fresh air, take off the contaminated clothes, and use clean water and 0.5% Sodium thiosulfate Rinse the contaminated skin, use 0.2% potassium permanganate, 5% sodium thiosulfate or 3% hydrogen peroxide for thorough gastric lavage after oral poisoning, pay attention to sedation, keep warm and absorb oxygen, inhale isoamyl nitrite and inject 10~15ml of 3% sodium nitrite in time, and perform artificial respiration in case of cardiac and respiratory arrest until being sent to the hospital.

Medical measures

Sodium nitrite sodium thiosulfate therapy. For moderate and mild patients Isoamyl nitrite Inhale and inject 3% sodium nitrite intravenously, and then inject 10~20mL of 50% sodium thiosulfate. For severe patients, 2mL of 10% 4-dimethylaminobenzoic acid was injected intramuscularly, and 10g of sodium thiosulfate was added; If the symptoms are repeated, the half dose can be repeated after 1 hour. At the same time of the above treatment, oxygen should be given. Those who have a long coma and severe hypoxia should actively prevent and treat brain edema.

application area

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Main purpose

Hydrogen cyanide is mainly used in electroplating industry (copper plating, gold plating, silver plating), mining industry (extracting gold and silver), cabin, warehouse fumigation and deratization, manufacturing various resin monomers such as acrylic resin, methacrylate resin, etc. In addition, it can also be exposed to this substance in the production process of cyanide preparation.

Prevention and control objects

Hydrocyanic acid is the first widely used Fumigant one of. Hydrocyanic acid can be used to control various forms of storage pests (except for mites). The toxicity of the drug to animals is stronger than that of active plants, so it is a good fumigant for fumigation of seedlings and seeds in fully dried dormant bodies. Generally, the germination rate of seeds will not be affected by the treatment of hydrocyanic acid. It is effective to treat dormant seedlings with hydrocyanic acid to prevent and kill scale insects, but after fumigation, they must be washed with clean water to prevent pesticide damage. The medicine is easily soluble in water, and dissolves into dilute acid in water. It cannot be safely used for fruits, vegetables and other high water content articles. Hydrocyanic acid is a good fumigant commonly used for many stored goods, grains and grains. Many objects have strong adsorption on hydrocyanic acid. If the fumigated goods are dry, this effect is reversible. Due to the strong adsorption, the penetration of the drug is limited. Therefore, it is recommended to use decompression fumigation. As hydrocyanic acid is highly toxic to warm blooded animals, it is often used as a rodenticide for ocean going ships.

usage method

1. Direct application of liquid hydrocyanic acid: this dosage form is convenient, safe, and labor saving. Its operation method is similar to that of methyl bromide. When using, attention should be paid to that if the storage period of hydrocyanic acid in the cylinder package exceeds 3 months, it must be returned to the original manufacturer to avoid explosion during use.

2. Cyanate gas is generated by reaction of cyanate salts:

(1) Calcium cyanide enters the water to generate cyanic acid gas: the use of calcium cyanide requires 15~26 ℃. When the relative humidity is 80%~90%, it is better to spread the calcium cyanide evenly on the paper and let it decompose by itself. The thickness of the paving should be 1~2mm. In case of dry weather, water should be sprayed around the agent properly; For example, calcium cyanide containing 50% cyanide is generally 25~35g/m three 。

(2) Sodium cyanide: sodium cyanide was the most widely used fumigant in China. The purity of NaCN for fumigation must be more than 98%, and the density of concentrated sulfuric acid reacted with it is 1.84g/cm three , do not dilute with well water. Theoretically, one part of sodium cyanide should be mixed with one part of concentrated sulfuric acid, but excessive acid can accelerate the generation of cyanic acid gas. The mixture of water and concentrated sulfuric acid can release heat to accelerate the reaction, but the temperature during heating should not be higher than 60~70 ℃, otherwise sulfuric acid will be reduced to CO two And SO two , reduce the production of HCN. If too much water is added, HCN cyanate gas will produce less water vapor and more water vapor, which will slow down the fumigation effect. If too little water is added, the sulfuric acid is too strong and the temperature is too high, and almost all products are carbon monoxide. Therefore, the ratio is of great significance to the fumigation effect. The recommended dosage of sodium cyanide NaCN is 30-40g/m three （10℃）。

(3) The price of potassium cyanide (KCN) is expensive, and it is generally used as a drug in laboratories.

matters needing attention

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Health hazards

Inhibits respiratory enzymes, causing intracellular asphyxia. Acute poisoning: Inhalation of high concentration of hydrogen cyanide gas in a short time can immediately stop breathing and cause death. The non sudden death was clinically divided into 4 stages: mucosal irritation, accelerated and deepened breathing, fatigue, headache in the prodromal stage; Oral numbness occurs at the tip of the tongue and mouth. Dyspnea period includes dyspnea, elevated blood pressure, bright red skin and mucous membrane, etc. Convulsive phase presents convulsion, coma and respiratory failure. During paralysis, the muscles of the whole body relax, breathing and heartbeat stop and die. May cause burns to eyes and skin, and may cause poisoning if absorbed. Chronic effects: neurasthenic syndrome, dermatitis.

First aid measures

Skin contact: Take off contaminated clothes immediately, and wash thoroughly with flowing clean water or 5% sodium thiosulfate solution for at least 20 minutes. Get medical attention.

Eye contact: immediately lift the eyelid, and thoroughly flush it with a large amount of flowing water or physiological saline for at least 15 minutes. Get medical attention.

Inhalation: quickly leave the site to a place with fresh air. Keep the respiratory tract unobstructed. If breathing is difficult, give oxygen. When breathing and heartbeat stop, perform artificial respiration (not mouth to mouth) and external chest compression immediately. Inhale isoamyl nitrite and seek medical advice.

Ingestion: drink enough warm water to induce vomiting. Use 1:5000 potassium permanganate or 5% sodium thiosulfate solution for gastric lavage. Get medical attention.

Fire extinguishing method

Cut off the air supply. If the air source cannot be cut off, it is not allowed to extinguish the flame at the leakage. Firefighters must wear special protective clothing and oxygen respirators, and operate beyond a safe distance or at a place with protective measures. Extinguishing agent: dry powder, insoluble foam, carbon dioxide. It is invalid to extinguish the fire with water, but the containers on the fire site must be kept cool with water. Use foggy water to disperse steam.

Common sense of safety

1. Contact opportunity: It is mainly used in electroplating industry (copper plating, gold plating, silver plating), mining industry (extracting gold and silver), fumigation and deratization in cabins and warehouses, manufacturing various resin monomers such as acrylic resin, methacrylic resin, etc. In addition, it can also contact this substance in the production process of cyanide preparation.

2. On site treatment: immediately break the 1-2 ampoule of isoamyl nitrite in a handkerchief, stick it in front of the mouth and nose and inhale it. At the same time, perform artificial respiration and pay attention to the vital signs.

3. Selection of gas mask: Due to the high toxicity of hydrogen acid gas, you must be careful when selecting and wearing gas masks. GB2890-82 IL gas filter tank is commonly used in China. When using other types of gas filter tank, you should carefully read the instructions and production date. Generally, the effective gas filtering time is only about 50 minutes in the concentration of 3g/m3 cyanic acid gas; Before use, chloropicrin should be used to test the effectiveness of the gas filter tank and whether the gas mask should be worn properly. In case of large-scale hydrocyanic acid fumigation, it is recommended that a fumigation team should have at least one self-contained breathing device to prevent accidents.