Acetaldehyde, also known as acetaldehyde, is an organic compound with the chemical formula CHthreeCHO is a colorless transparent liquid, soluble in water, and miscible in ethanol, ether, benzene, gasoline, toluene, xylene, etc. It is mainly used as a reducing agent, bactericide, and to prepare standard solutions when measuring aldehyde by colorimetric method. It is used in industry to manufacture polyacetaldehyde, acetic acid, synthetic rubber, etc.
On October 27, 2017, the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization (WHO) was preliminarily sorted out for reference, and acetaldehyde was included in the list of Category 2B carcinogens.[16]
Colorless liquid, with strong irritating odor, easy to volatilize.
Functional groups contained
Aldehyde group (- CHO)
Melting point (℃)
-123
Boiling point (℃)
twenty point eight[18]
Relative density (water=1)
zero point seven eight
Saturated vapor pressure (kPa)
98.64（20℃）
Combustion heat (kJ/mol)
-1166.37
Critical temperature (℃)
one hundred and eighty-eight
Flash point (℃)
-40
Ignition temperature (℃)
one hundred and seventy-five
Upper explosive limit
57.0%（V/V）
Lower explosive limit
4.0%（V/V)
Solubility
It is miscible with water, ethanol, ether, chloroform, etc.
chemical property
Combustible
Most of the products sold on the market are 40% acetaldehyde aqueous solution. To get high purity acetaldehyde, go toParaldehyde98% of 1% - 5%concentrated sulfuric acid, distilled.The condensed water shall be ice water, and the bottle shall be placed in the ice water and operated carefully.The obtained acetaldehyde is sealed and placed in the refrigerator.
Important reactions
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Industrial acetaldehyde equation:
Acetylene hydration method:
[1]
Ethylene oxidation method:
Acetaldehyde catalytic oxidation:
[2]
Acetaldehyde combustion:
Silver mirror reaction:
[3]
Acetaldehyde and newly prepared copper hydroxide:
Acetaldehyde reacts with hydrogen to produce ethanol:
synthetic method
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Direct oxidation of ethylene
Ethylene and oxygen are directly oxidized to crude acetaldehyde in one step through a catalyst containing palladium chloride, copper chloride, hydrochloric acid and water, and then the finished product is obtained through distillation.[4]
Ethanol oxidation
Acetaldehyde was prepared by oxidative dehydrogenation of ethanol vapor to air at 300-480 ℃ using silver, copper or silver copper alloy mesh or particle as catalyst.[5]
Acetylene direct hydration
Acetylene and water are directly hydrated to obtain acetaldehyde under the action of mercury catalyst or non mercury catalyst.Due to the mercury hazard, it has been gradually replaced by other methods.[6]
Ethanol dehydrogenation
Ethanol is dehydrogenated to acetaldehyde under the action of copper catalyst added with cobalt, chromium, zinc or other compounds.[7]
Main purpose
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In organic synthesis, acetaldehyde is a bicarbon reagentElectrophilic reagent, as CHthreeThe synthon of CH (OH) is prochiral.It is condensed with three parts of formaldehyde to formPentaerythritolC(CHtwoOH)four。[8]It reacts with Grignard reagent and organic lithium reagent to form alcohol.
In Strecker amino acid synthesis, acetaldehyde can be synthesized after condensation and hydrolysis with cyanide ion and ammoniaalanine 。[9]Acetaldehyde can also construct heterocyclic ring systems, such asParaldehydeIt reacts with ammonia to form pyridine derivatives.[10]
In addition, acetaldehyde can be used to produce acetic acid, ethanol and ethyl acetate.The pesticide DDT is synthesized from acetaldehyde.Acetaldehyde is chlorinated to trichloroacetaldehyde.The hydrate of trichloroacetaldehyde is a sleeping drug.
Application and recommended dosage
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It can be used to mix fruit flavors such as oranges, oranges, apples, apricots, strawberries, and wine flavors such as wine, rum, whisky, etc.The concentration in the final flavored food is about 3.9~270 mg/kg[11]。
Toxicological data
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Acute toxicity:LDfifty1930 mg/kg (rat oral);LCfifty37000mg/mthree, 1/2 hour (inhaled by rats),[12]This concentration makes animals appear obvious excitement symptoms;Anesthesia appeared after 15min;The survivors recovered quickly.The main finding of animal autopsy was pulmonary edema.Cat exposure 2g/mthreeSerious irritation symptoms, 20g/mthreeIn case of concentration, the patient died of respiratory paralysis after 1-2h.
Subacute and chronic toxicity:Similar to alcoholism.The symptoms include weight loss, anemia, delirium, audio-visual hallucinations, intellectual loss and mental disorders.
Metabolism:Acetaldehyde enters human body mainly through respiratory tract and gastrointestinal tract.About 40%~70% of the inhaled acetaldehyde vapor remains in the respiratory tract, and the concentration of acetaldehyde entering the blood in red blood cells is about 10 times that in plasma.Acetaldehyde in vivo mainly depends on liver NADAldehyde dehydrogenaseOxidative metabolismacetic acid, further generate COtwoAnd water.Acetaldehyde is also an intermediate product of glucose metabolism in the body. Acetaldehyde is NAD dependent for ethanol via the liverAlcohol dehydrogenaseFormed by oxidative metabolism.
Poisoning mechanism:Acetaldehyde isethanolA product metabolized in the body, it can cause uncomfortable symptoms such as flushing, palpitations and blood pressure drop.These effects can be aggravated by simultaneous exposure to dithiothiuram (also known as "Antabuse", which can be used as an alcohol abstainer and rubber antioxidant), cyanamide and dicarbonamide. Acetaldehyde, one of the components in cigarette mist, has ciliary toxicity and can reduce the number of pulmonary macrophages.
thrill:Rabbit via eye: 40mg, severe irritation.Percutaneous open stimulation test in rabbits: 500mg, mild stimulation.
Teratogenicity:Teratogenicity test of higher animals is negative, but it can cause chromosome aberration of plants and lower animals.
Reproductive toxicity:The lowest toxic dose (TDL0) of mouse vein: 120mg/kg (used for 7-9 days after pregnancy), the mortality rate after blastocyst implantation is increased, and it is toxic to fetal rats.
Environmental hazards:It is harmful to the environment and can cause pollution to water bodies.
Explosion hazard:This product is extremely flammable, irritant and allergic.
molecular structure
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The C atom of methyl is represented by spthreeThe C atom of hybrid orbital bonding, aldehyde group and sptwoThe hybrid orbitals form bonds, and the molecules are polar molecules.
Physical and chemical properties
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physical property
melting point
-123℃
boiling point
20.8℃[18]
density
0.788g/cmthree
flash point
-40℃
Refractive index
1.377（20℃）
Saturated vapor pressure
98.64kPa（20℃）[17]
critical temperature
188℃[17]
critical pressure
6.4MPa[17]
Pilot temperature
175℃[17]
Upper explosive limit（V/V）
57%[17]
Lower explosive limit（V/V）
4%[17]
appearance
Colorless Transparent Liquid
Solubility
Soluble in water, miscible in ethanol, ether, benzene, gasoline, toluene, xylene, etc[15]
chemical property
1. Catalytic oxidation of acetaldehyde
2. Acetaldehyde combustion
3. Silver mirror reaction
4. Acetaldehyde and new copper hydroxide
5. Acetaldehyde reacts with hydrogen to produce ethanol
Molecular structure data
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Molar refractive index
eleven point five zero[17]
Molar volume (cmthree/mol）
fifty-eight point eight[17]
Isotonic specific volume (90.2K)
one hundred and twenty point six[17]
Surface tension (dyne/cm)
seventeen point six[17]
Polarization (10-24cmthree）
four point five five[15]
Calculate chemical data
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Drainage parameter calculation reference value (XlogP)
-0.3[17]
Number of hydrogen bond donors
zero[17]
Number of hydrogen bond receptors
one[17]
Number of rotatable chemical bonds
zero[17]
Number of tautomers
two
Topological molecular polar surface area
seventeen point one[17]
Number of heavy atoms
three
surface charge
zero[17]
Complexity
ten point three[17]
Number of isotope atoms
zero[17]
Determine the number of atomic geometric centers
zero[17]
Number of atomic geometric centers in uncertainty
zero[17]
Determine the number of chemical bond stereocenters
Rats and guinea pigs can tolerate 100mg/kg orally for 6 months, and have reflex dysfunction and elevated arterial pressure;Oral administration of 10mg/kg for 2-3 months can also cause the same changes.[17]
Sister chromatid exchange: human lymphocytes 40μmol/L。[17]
DNA damage: human lymphocytes 1560μmol/L。[17]
DNA inhibition: 10 mmol/L for human HeLa cells.[17]
Sister chromatid exchange: human lymphocytes 1200μmol/L。[17]
Teratogenicity
The lowest toxic dose (TDLo) was administered orally or intraperitoneally to rats and mice at different times after pregnancy, resulting in malformations of the respiratory system, hepatobiliary system, central nervous system, endocrine system, urogenital system, musculoskeletal system, and craniofacial (including nose and tongue) development.
carcinogenicity
IARC carcinogenicity review: G2B, suspected human carcinogen.
other
The lowest toxic dose (TDLo) of mouse vein: 120mg/kg (used for 7-9 days after pregnancy), the mortality rate after blastocyst implantation is increased, and it is toxic to fetal rats.[15]
MITI-I test shows that the initial concentration is 100ppm, the sludge concentration is 30ppm, and the degradation rate is 80% after 2 weeks.[17]
3. Non biodegradable
In the air, when the concentration of hydroxyl radical is 5.00 × 10fivePcs/cmthreeThe half-life of degradation is 24h (theoretical)[17]。
Photolysis half-life in atmosphere is 8.4~16h.[15]
purpose
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It is mainly used as reducing agent, bactericide and preparation of standard solution when determining aldehyde by colorimetric method. It is used in industry to manufacture paraldehyde, acetic acid, synthetic rubber, etc.
First aid measures
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Skin contact: Take off the contaminated clothes and wash the skin thoroughly with soapy water and clean water.
Eye contact: Lift the eyelid and flush with flowing water or physiological saline.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.If breathing stops, perform artificial respiration immediately.Get medical attention.
Ingestion: drink enough warm water to induce vomiting.Get medical attention.
Leakage emergency treatment
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Evacuate the personnel in the leakage contaminated area to a safe area quickly, isolate them, and strictly restrict access.Cut off the ignition source.It is recommended that emergency personnel wear self-contained positive pressure respirators and anti-static work clothes.Cut off the leakage source as much as possible.Prevent from flowing into restricted spaces such as sewers and flood discharge ditches.
Small amount of leakage: absorb or absorb with sand or other incombustible materials.A large amount of water can also be used for flushing, and the diluted washing water will be discharged into the waste water system.
Large amount of leakage: build a dike or dig a pit to receive.Spray water cools and dilutes steam, protects on-site personnel, and dilutes leakage into incombustible materials.Use explosion-proof pump to transfer to tank car or special collector for recycling or transport to waste disposal site.
Protective treatment
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protect
1. Keep away from fire sources.
2. Take measures to prevent static electricity.
3. Wear appropriate protective clothing and gloves.
Acetaldehyde shall be contained in pressure resistant glass bottles or metal drums.Containers must be stored in a well ventilated warehouse with air conditioning equipment and a structure of non combustible materials, away from kindling and heat sources, and protected from direct sunlight.It should be separated from oxidants, strong alkalis, ammonia, amines, halogens, alcohols+ketones, phenols and other substances, as well as substances burning in water.The package must be firm and sealed, and should not be stored for a long time.Handle with care.
Fog water, dry powder, alcohol resistant foam, carbon dioxide and dry sand can be used for fire extinguishing.
When materials leak out.First, cut off the fire source, ventilate and flush with water.The diluted washing water is discharged into the waste water system.
Emergency disposal
Skin contact:Take off contaminated clothes and wash skin thoroughly with soapy water and clean water.
Eye contact:Lift the eyelids and wash them with flowing water or normal saline.Get medical attention.
Inhalation:Quickly leave the site to fresh air.Keep the respiratory tract unobstructed.If breathing is difficult, give oxygen.If breathing stops, perform artificial respiration immediately.Get medical attention.
Ingestion:Drink enough warm water to induce vomiting.Get medical attention.
Leakage emergency treatment:Evacuate the personnel in the leakage contaminated area to a safe area quickly, isolate them, and strictly restrict access.Cut off the ignition source.It is recommended that emergency personnel wear self-contained positive pressure respirators and anti-static work clothes.Cut off the leakage source as much as possible.Prevent from flowing into restricted spaces such as sewers and flood discharge ditches.Small amount of leakage: absorb or absorb with sand or other incombustible materials.A large amount of water can also be used for flushing, and the diluted washing water will be discharged into the waste water system.Large amount of leakage: build a dike or dig a pit to receive.Spray water cools and dilutes steam, protects on-site personnel, and dilutes leakage into incombustible materials.Use explosion-proof pump to transfer to tank car or special collector for recycling or transport to waste disposal site.
Fire extinguishing method:In case of fire, firefighters must operate in the place with explosion-proof shelter.Soluble foam, carbon dioxide, dry powder, sand.Fire extinguishing with water is invalid.
Emergency medical treatment
Main uses and contact opportunities: Used for manufacturing acetic acid, acetic anhydride and synthetic resin.
Human hazard: Low concentration causes eye, nose and upper respiratory tract irritation symptoms and bronchitis.Inhalation of high concentration still has anesthetic effect.The symptoms include headache, lethargy, confusion, bronchitis, pulmonary edema, diarrhea, proteinuria, liver and myocardial steatosis.May cause death.Gastrointestinal irritation, anesthetic effect, and heart, liver, and kidney damage occur when taken by mistake.It is allergic to skin.Repeated exposure to steam may cause dermatitis and conjunctivitis.
Diagnostic points:
(1) Mild inhalation poisoning is manifested as eye and upper nasal respiratory tract irritation symptoms and bronchitis, and severe inhalation poisoning is manifested as pulmonary edema, headache, somnolence, and disturbance of consciousness.
(2) The symptoms of oral poisoning include nausea, vomiting, diarrhea, disturbance of consciousness, and liver, kidney and myocardial damage.
(3) Skin contact may cause irritant contact dermatitis, and sometimes allergic contact dermatitis.
Handling principle:
(1) Those poisoned by inhalation should leave the scene quickly.If necessary, inhale oxygen, atomize inhalation, 2% sodium bicarbonate, dexamethasone, etc.Give antitussive and antispasmodic drugs.Dexamethasone 10mg was given intravenously at the early stage.In case of pneumonia or pulmonary edema, symptomatic treatment should be carried out as soon as possible.
(2) After ingestion by mistake, wash the stomach with clean water as soon as possible. After gastric lavage, 100mL of 3% ammonium carbonate or 15% ammonium acetate can be given, and milk or soy milk can be taken orally to protect the gastric mucosa.
(3) After contact between skin and mucous membrane, wash with plenty of water first, then wash with soapy water or 2% sodium bicarbonate solution, and replace contaminated clothes.
(4) Allergic patients can be given anti allergic drugs.
preventive measure: Closed system to prevent smoke generation.Fire and explosion prevention.
Handling and storage
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Operation precautions: closed operation, full ventilation.Operators must be specially trained and strictly abide by the operating procedures.It is recommended that operators wear filter type gas masks (half masks), chemical safety goggles, anti-static work clothes and rubber gloves.Keep away from kindling and heat sources, and smoking is strictly prohibited in the workplace.Use explosion-proof ventilation systems and equipment.Prevent vapor leakage into the air of the workplace.Avoid contact with oxidants, reducing agents and acids.The flow rate shall be controlled during filling to prevent the accumulation of static electricity.Load and unload gently during transportation to prevent damage to packaging and containers.Fire fighting equipment and leakage emergency treatment equipment of corresponding types and quantities shall be provided.Empty containers may leave harmful substances.
Precautions for storage: store in a cool and ventilated warehouse.Keep away from kindling and heat sources.The warehouse temperature should not exceed 25 ℃.The package shall be sealed and shall not contact with air.It shall be stored separately from oxidants, reducing agents, acids, etc., and shall not be mixed.It should not be stored in large quantities or for a long time.Explosion proof lighting and ventilation facilities shall be adopted.It is prohibited to use mechanical equipment and tools that are easy to generate sparks.The storage area shall be equipped with leakage emergency treatment equipment and appropriate materials.
Contact control
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Former Soviet Union MAC (mg/mthree）
five
TLVTN
OSHA 200ppm； ACGIH 100ppm,180mg/mthree
TLVWN
ACGIH 150ppm，270mg/mthree
Monitoring methods
Solvent desorption gas chromatography
engineering control
Closed operation, full ventilation.Provide safety shower and eyewash equipment.
Individual protection
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Protective parts
Protective measures
respiratory system protection
When the concentration in the air exceeds the standard, wear a filtered gas mask (half mask).
Eye protection
Wear chemical safety goggles.
Body protection
Wear anti-static work clothes.
Hand protection
Wear rubber gloves.
Other protection
Smoking, eating and drinking are prohibited at the work site.After work, take a shower and change clothes.Keep good hygiene habits.[13]
Transport information
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Dangerous goods No
thirty-one thousand and twenty-two
UN No
one thousand and eighty-nine
Packing group
O51
Packaging method: Steel gas cylinder;Ordinary wooden case outside ampoule bottle;Screw mouth glass bottles, iron cap pressure mouth glass bottles, plastic bottles or ordinary wooden boxes outside metal barrels (cans);Tank truck (filling coefficient 0.626 t/m3).
Transportation precautions: The railway transportation time limit of this product is to use the self provided tank car of the pressure resistant liquefied gas enterprise for shipment, and it needs to be reported to the relevant department for approval before shipment.The transport vehicles shall be equipped with corresponding types and quantities of fire-fighting equipment and leakage emergency treatment equipment.It is better to transport in the morning and evening in summer.The tank (tank) car used for transportation shall be equipped with grounding chain, and the tank can be equipped with hole partition to reduce static electricity generated by vibration.It is strictly prohibited to mix with oxidants, reducing agents, acids, edible chemicals, etc.During transportation, it shall be protected from sun exposure, rain and high temperature.Keep away from kindling, heat source and high temperature area during stopover.The exhaust pipe of the vehicle transporting this article must be equipped with a fire retardant device. It is prohibited to use mechanical equipment and tools that are easy to generate sparks for loading and unloading.Road transportation shall be carried out according to the specified route, and do not stay in residential areas and densely populated areas.It is forbidden to slip during railway transportation.It is strictly prohibited to transport in bulk by wooden boat or cement boat.
Regulatory information
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Regulations on the Safety Management of Dangerous Chemicals (issued by the State Council on February 17, 1987), detailed rules for the implementation of the Regulations on the Safety Management of Dangerous Chemicals (HLF [1992] No. 677), regulations on the safe use of chemicals in the workplace (LBF [1996] No. 423) and other regulations have made corresponding provisions on the safe use, production, storage, transportation, loading and unloading of dangerous chemicals;The classification and signs of commonly used hazardous chemicals (GB 13690-92) classify this substance as Class 3.1 low flash point flammable liquid.[14]
Vehicle limit requirements
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According to HJT 400-2007 Sampling and Determination Method for Volatile Organic Compounds and Aldehydes and Ketones in Vehicles, and GBT 27630-2011 Guidelines for Air Quality Assessment in Passenger Cars.Acetaldehyde ≤ 0.05mg/m
security information
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Safety terminology
S16：Keep away from sources of ignition - No smoking.
Keep away from ignition sources and no smoking.
S26：In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.
After eye contact, immediately flush with plenty of water and seek medical advice.
S33：Take precautionary measures against static discharges.
Take precautions against static electricity.
S36/37：Wear suitable protective clothing and gloves.
