Ammonium thiocyanate is an inorganic substance with the chemical formula NHfourSCN，Colorless crystal.Irritating, easily deliquescent, easily soluble in water and ethanol, soluble in methanol and acetone, almost insoluble in chloroform andethyl acetate。Its aqueous solution will be blood red when it encounters iron salt solution, and will not react when it encounters ferrous salt.When heated to 159 ℃, the dried product will not decompose and melt, and when heated to 170 ℃, the molecule will change into thiourea.The relative density is 1.305.The melting point is about 149 ℃.Toxic,Minimum lethal dose(Mice, oral) 330mg/kg.
Appearance and properties: colorless and lustrous monoclinic system lamellar or columnar crystals, diamond crystals at 92 ℃.Soluble in water, endothermic reaction when soluble in water, soluble in ethanol, alkali metal hydroxide, acetone, pyridine andLiquid sulfur dioxideMedium, insoluble in chloroform（Trichloromethane)。The solution is red in sunlight.
Melting point (℃): 149.6
Relative density (water=1): 1.31
Boiling point (℃): 170 (decomposition)
CAS NO.1762-95-4
Molecular formula: NHfourSCN
Molecular weight: 76.12
Solubility: soluble in water, ethanol, acetone, ammonia[1]。
Calculate chemical data
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1. Number of hydrogen bond donors: 1;
2. Number of hydrogen bond receptors: 2;
3. Number of rotatable chemical bonds: 0;
4. Topological molecular polar surface area (TPSA): 24.8;
9. Determine the number of atomic structure centers: 0;
10. Number of uncertain atomic structure centers: 0;
11. Determine the number of chemical bond structure centers: 0;
12. Number of uncertain chemical bond structure centers: 0;
13. Number of covalent bond units: 2[1]。
chemical property
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Bloody red when encountering iron saltFerric thiocyanide, does not react with ferrous salt.The solution is red under the action of sunlight.Thiourea is formed when heated to about 140 ℃.Decomposition into ammonia at 170 ℃carbon disulfideAnd hydrogen sulfide.Deliquescence[1]。
preparation
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1. From ammonium cyanide aqueous solution and sulfur orPolysulfideIt is made by co heating.
In industry, it is generally produced by the coking waste liquid double salt purification device, which is now available in some small steel plants in North China and Central China.
2. It is prepared by reacting carbon disulfide with liquid ammonia under pressure.Or the slurry of sulfur and water reacts with sodium cyanide, and then reacts with solid ammonium chloride.
3. In the carbon disulfide method, carbon disulfide and slightly excess liquid ammonia are mixed with water, and react for about 20h under the pressure of 5.88 × 105Pa and temperature of 100 ℃ to generate ammonium thiocyanate.The reaction liquid is evaporated under reduced pressure to remove hydrogen sulfide. When the liquid temperature is 105 ℃, remove iron and heavy metals with ammonium sulfide, filter, concentrate the filtrate under reduced pressure, cool and crystallize in a crystallizer, and then centrifugate and dry to obtain ammonium thiocyanate.
4. The sulfur yellow method is to mix a proper amount of water and sulfur yellow powder in the reactor to form a slurry. The solid sodium cyanide is slowly added in batches. The reaction is carried out at about 110 ℃ to generate sodium thiocyanide, and then the solid ammonium chloride is added to generate ammonium thiocyanate. Barium thiocyanate is added to the reaction solution to remove impurities and clarify it. The supernatant is evaporated under reduced pressure, concentrated and separated out sodium chloride, and then filteredAmmonium thiocyanate was prepared by cooling crystallization, separation and drying.
5. Cooked with ammonium cyanide solution and sulfur powder.
6. Carbon disulfide and ammonia water are subject to pressure synthesis reaction to generate ammonium thiocyanate and by-product ammonium hydrosulfide, and then ammonium hydrosulfide is decomposed into hydrogen sulfide by desulfurization and evaporation to remove hydrogen sulfide. The resulting solution is removed impurities and separated to obtain the product.Or react sulfur with sodium cyanide to formSodium thiocyanate, and then mixed with ammonium chlorideMetathesis reactionProduce ammonium hydrosulphate.
7. For the preparation method, dissolve the industrial ammonium thiocyanate with appropriate amount of water, heat it to 60 ℃, and then add appropriate amount of barium sulfide (calculated by the weight of impurities in the raw material)Ammonium hydroxide(relative density 0.91) and barium hydroxide to remove heavy metal ions and SOfour2-Ions.Let it stand for clarification, pour out the clear liquid, add a small amount of ammonia water and activated carbon, evaporate at 60 ℃ until the relative density is 1.15, stir, cool, crystallize and filter by suction.The crystal is dissolved in a small amount of distilled water at 60 ℃, and the SO in the solution is routinely testedfour2-And Ba2+(If the content does not meet the requirements, add barium hydroxide or ammonium sulfate according to the calculated amount, and add a small amount of activated carbon). After meeting the requirements, filter at 60 ℃, cool and crystallize, filter by suction, wash with a small amount of distilled water, and finally dry at 30~40 ℃ to obtain analytical pure ammonium thiocyanate[2]。
application
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Inorganic industry is used to manufacture cyanide, thiocyanate, ferrocyanide, thiourea and auxiliary materials for hydrogen peroxide production.Organic industry is used as catalyst for polymerization.The pharmaceutical industry is used in the synthesis and separation of antibiotics.The electroplating industry is used for galvanizing.The printing and dyeing industry is used as a printing and dyeing dispersant.The pesticide industry is used to manufacture Ye Qingshuang, etc.The steel industry is used to prepare pickling agent.In analytical chemistry, silver, mercury, trace iron determination, pesticide nitrogen content analysis, water quality analysis, and standard solution of thiocyanate were used.
It is used as a blackening agent in black nickel plating electrolyte and in analytical chemistry to determine iron and silver plasma in electrolyte.
matters needing attention
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Hazard Overview
Health hazard: Irritating to eyes and skin.Poisoning is mainly caused by misuse, resulting in nausea, vomiting, abdominal pain, diarrhea, blood pressure reduction, etc.There were reports of poisoning caused by taking 15% 200ml of the product orally, which was cured after treatment;Take 0.1g continuously 1-3 times a day for more than 3 weeksToxic psychosisAnd reports of fatal accidents.
Environmental hazard: It is harmful to the environment and can cause pollution to the water body.
Flammability hazard: the product is nonflammable, toxic and irritating[2]。
Safety terminology
S13Keep away from food, drink and animal foodstuffs.
Keep away from food, drink and animal feed.
S61Avoid release to the environment. Refer to special instructions / safety data sheets.
Avoid release to the environment.Refer to Special Instructions/Safety Data Sheet.
Risk terminology
R20/21/22Harmful by inhalation, in contact with skin and if swallowed.
Harmful by inhalation, skin contact and if swallowed.
R32Contact with acid liberates very toxic gas.
Contact with acid releases extremely toxic gas.
R52/53Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
It is harmful to aquatic organisms and may have long-term adverse effects on the water environment.
First aid measures
Skin contact: Take off contaminated clothes and wash with plenty of flowing water.
Eye contact: lift the eyelid, use flowing water ornormal salinerinse.Get medical attention.
Inhalation: leave the site to fresh air.asdyspnea, give oxygen.Get medical attention.
Ingestion: drink enough warm water to induce vomiting.Gastric lavage and catharsis.Get medical attention.
Fire fighting measures
Hazard characteristics: non combustible.It is decomposed by heat and emits toxic gases such as oxides of nitrogen and sulfur.
Extinguishing method: firefighters must wear full body fire and gas protective clothing and extinguish the fire upwind.When putting out a fire, move the container from the fire site to an open place as far as possible[1]。
Leakage emergency treatment
Emergency treatment: isolate the leakage contaminated area and restrict access.It is recommended that emergency handling personnel wearDust mask(Full face mask), wear anti-virus clothing.Collect with a clean shovel in a dry, clean, covered container and transfer to a safe place.In case of large leakage, collect and recycle or transport to waste disposal site for disposal.
Operation and storage
Precautions for operation: it shall be strictly sealed, and sufficient local exhaust and general ventilation shall be provided.Operators must be specially trained and strictly abide by the operating procedures.Recommended for operatorsSelf suction filtering dust maskWear chemical safety goggles, anti poison penetration work clothes and rubber gloves.Avoid dust generation.Avoid contact with oxidants and acids.Load and unload gently during transportation to prevent damage to packaging and containers.Provide leakage emergency treatment equipment.Empty containers may leave harmful substances.
Precautions for storage: store in a cool and ventilated warehouse.Keep away from kindling and heat sources.The package shall be sealed and shall not contact with air.It shall be stored separately from oxidants, acids and edible chemicals, and mixed storage is strictly prohibited.The storage area shall be equipped with appropriate materials to contain leakage[2]。
