methanol

Saturated monohydric alcohol with the simplest structure

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This entry is made by Institute of Process Engineering, Chinese Academy of Sciences, School of Chemical Sciences, University of Chinese Academy of Sciences Participate in editing and review Science Popularization China · Science Encyclopedia authentication.

Methanol hydroxyl methane 、 wood alcohol (wood alcohol) or Lignin (wood spirits), an organic compound, is a saturated monohydric alcohol with the simplest structure, and its chemical formula is CH three OH/CH four O。 The molecular weight is 32.04, and the boiling point is 64.7 ℃. Methanol, known as "xylitol" and "lignin", originates from the fact that its main production method was extraction from wood vinegar (one of the products of wood carbonization or pyrolysis). Modern methanol is produced directly from a catalytic industrial process of carbon monoxide, carbon dioxide and hydrogen. Methanol is light, volatile, colorless, flammable, and has a smell very similar to ethanol (drinking wine). But unlike ethanol, methanol is toxic and cannot be drunk. It is usually used as solvent, antifreeze, fuel or ethanol denaturant, and can also be used to produce biodiesel through transesterification^[1] 。

Chinese name: methanol^[2]
Foreign name: methanol^[2]
Alias: Hydroxymethane 、 wood alcohol^[2] 、 Lignin^[2]
chemical formula: Structural simple form CH three OH； Molecular formula CH four O
molecular weight: thirty-two point zero four two^[2]
CAS login number: 67-56-1^[2]
EINECS login number: 200-659-6^[2]
Melting point: -97.8 ℃
Boiling point: 64.8 ℃
Density: 0.791 g/cm³
Appearance: colorless liquid
Flash point: 11.1 ℃^[2]
Application: Used for manufacturing formaldehyde, pesticide, etc

Security description: S7；S16；S36/37；S45^[2]
Hazard symbol: F^[2]
Hazard description: R11；R39/23/24/25
UN dangerous goods number: one thousand two hundred and thirty^[2]
Solubility: Soluble in water, miscible in most organic solvents such as alcohol and ether
Refractive index: one point three three zero six six
SMILES: CO
RTECS: PC1400000
Viscosity: 0.55 mPa·s，25℃
dipole moment: 1.69 D (gaseous)
Main hazards: Alcohol containing methanol can cause blindness and liver disease
Autoignition point: 473 ℃

catalog

history

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The ancient Egyptians used a mixture of methanol to preserve the corpse in the process of preserving it. However, it was not until 1661 that Robert Boyle first separated pure methanol by distillation Boxwood (boxwood). It later became known as the "pyramidal spirit". In 1834, French chemists Jean Baptiste Duma and Eugene Pirigo determined its element composition.

In 2006, astronomers found a huge methanol cloud 288 million miles wide in space using the radio telescope in the MERLIN array of Jodrelbank Observatory.

Molecular structure diagram of methanol (source: https://www.veer.co

Physical and chemical properties

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physical property

1. Character: colorless transparent liquid with pungent smell.

2. Melting point (℃): -97.8

3. Boiling point (℃): 64.7

4. Relative density (water=1): 0.792

5. Relative vapor density (air=1): 1.1

6. Saturated vapor pressure (kPa): 12.3 (20 ℃)

7. Combustion heat (kJ/mol): - 723

8. Critical temperature (℃): 240

9. Critical pressure (MPa): 7.95

10. Octanol/water partition coefficient: -0.82~-0.77

11. Flash point (℃): 12 (CC); 12.2（OC）

12. Ignition temperature (℃): 464

13. Upper explosive limit (%): 36.5

14. Lower explosive limit (%): 6

15. Solubility: soluble in water, miscible with most organic solvents such as alcohol and ether.

16. Refractive index (n20 º C): 1.3284

17. Viscosity (mPa · s, 15 º C): 0.6405

（mPa·s,20ºC）：0.5945

（mPa·s,25ºC）：0.5525

（mPa·s,30ºC）：0.5142

18. Flash point (º C, opening): 11 [y1]

22. Flash point (º C, closed): 12.0

23. Evaporation heat (KJ/mol, b.p.): 35.32

24. Melting heat (KJ/kg): 98.81

25. Heat of generation (KJ/mol, gas): - 2013.39

26. Heat of generation (KJ/mol, liquid): - 238.82

27. Specific heat capacity (KJ/(kg · K), 20 º C, constant pressure): 2.51

28. Boiling point rise constant: 0.785

29. Conductivity (S/m, 25 º C): 1.5 × 10 -9

30. Thermal conductivity: 0.0144 (W/(m · K), 0 º C), 0.0222 (W/(m · K), 100 º C)^{[9 ]}

31. Body expansion coefficient (K-1,20 º C): 0.00119

32. Body expansion coefficient (K-1,55 º C): 0.00124

33. Relative density (25 ℃, 4 ℃): 1.7866

34. Relative density (25 ℃, 4 ℃): 1.3265

35. Critical density (g · cm -3 ）：0.273

36. Critical volume (cm three ·mol -1 ）：117

37. Critical compressibility factor: 0.223

38. Eccentricity factor: 0.566

39. Lennard Jones parameter (A): 3.8632

40. Lennard Jones parameter (K): 419.86

41. Solubility parameter (J · cm -3 )0.5：29.532

42. van der Waals area (cm two ·mol -1 ）：3.580×10 nine

43. van der Waals volume (cm three ·mol -1 ）：21.710

44. Gas phase standard combustion heat (enthalpy) (kJ · mol -1 )：764.9

45. Gas phase standard claimed heat (enthalpy) (kJ · mol -1 ) ：-201.5

46. Standard entropy of gas phase (J · mol -1 ·K -1 ) ：239.88

47. Gas phase standard free energy of formation (kJ · mol -1 )：-161.6

48. Gas phase standard hot melt (J · mol -1 ·K -1 )：44.06

49. Standard combustion heat of liquid phase (enthalpy) (kJ · mol -1 )：-726.9

50. Liquid standard claimed heat (enthalpy) (kJ · mol -1 )：-239.1

51. Standard entropy of liquid phase (J · mol -1 ·K -1 ) ：127.24

52. Standard free energy of formation in liquid phase (kJ · mol -1 )：-166.88

53. Liquid standard hot melt (J · mol -1 ·K -1 )：81.4^[1]

chemical property

Methanol is composed of methyl and hydroxyl groups and has the chemical properties of alcohol.

Methanol can react with fluorine, oxygen and other gases, and burn violently in pure oxygen to generate water vapor and carbon dioxide

2CH three OH+3O two =2CO two +4H two O

Moreover, methanol can also undergo ammoniation reaction (370 ℃~420 ℃)

NH three +CH three OH→CH three NH two +H two O

NH three +2CH three OH→(CH three ) two NH+2H two O

NH three +3CH three OH→(CH three ) three N+3H two O

Methanol can also be burned in air:

Methanol has the general property of saturated monohydric alcohol. Since there is only one carbon atom, it has its own unique reaction. For example:

① It forms crystalline substance CaCl with calcium chloride two ·4CH three OH， Forming BaO · 2CH with barium oxide three Molecular compound of OH and dissolved in methanol; Similar compounds include MgCl two ·6CH three OH、CuSO four ·2CH three OH、CH three OK·CH three OH、AlCl three ·4CH three OH、AlCl three ·6CH three OH、AlCl three ·10CH three OH, etc

4CH three OH+CaCl two →CaCl two ·4CH three OH

2CH three OH+BaO→2CH three OH·BaO

② Different from other alcohols, due to - CH two OH group combines with hydrogen, and formic acid generated during oxidation is further oxidized to CO two

2CH three OH+O two →2HCHO+2H two O

2HCHO+O two →2HCOOH

2HCOOH+O two →2H two O+2CO two

③ Methanol and chlorine 、 bromine It is not easy to react, but it is easy to react with its aqueous solution to initially generate dichloromethyl ether (CH two Cl) two O， It is converted into HCHO and HCl due to the action of water

2CH three OH+2Cl two =(CH two Cl) two O+H two O+2HCl

(CH two Cl) two O+H two O=2HCHO+2HCl

④ Heating with alkali and lime to generate hydrogen and sodium formate

CH three OH+NaOH→HCOONa+2H two

⑤ Distill together with zinc powder to decompose and generate CO and H2O^[3]

Molecular structure data

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1. Molar refractive index: 8.21

2. Molar volume (cm three /mol）：42.5

3. Isotonic specific volume (90.2K): 88.6

4. Surface tension (dyne/cm): 18.8

5. Polarization (10 -24 cm three ）：3.25^[1]

Calculate chemical data

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1. Reference value of drainage parameter calculation (XlogP): - 0.5

2. Number of hydrogen bond donors: 1

3. Number of hydrogen bond receptors: 1

4. Number of rotatable chemical bonds: 0

5. Number of tautomers: none

6. Topological molecular polar surface area 20.2

7. Number of heavy atoms: 2

8. Surface charge: 0

9. Complexity: 2

10. Number of isotope atoms: 0

11. Determine the number of atomic structure centers: 0

12. Number of uncertain atomic structure centers: 0

13. Determine the number of chemical bond structural centers: 0

14. Number of indeterminate chemical bond structure centers: 0

15. Number of covalent bond units: 1^[1]

purpose

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1. One of the basic organic raw materials for manufacturing Methyl chloride 、 Methylamine and Dimethyl sulfate And other organic products. It is also a pesticide (insecticide, acaricide), medicine（ Sulfonamides 、 Synmycin Raw materials, synthetic pairs Phthalic acid Dimethyl ester Methyl methacrylate and Methyl acrylate One of the raw materials of.^[4]

2. Methanol is mainly used in the production of formaldehyde, which can be used to produce adhesives, mainly in the wood processing industry, and secondly as a treatment agent for molding plastics, coatings, textiles and paper.

3. Another main use of methanol is to produce acetic acid. Acetic acid consumption accounts for about 7% of global methanol demand, which can be produced vinyl acetate 、 acetate fibre and Acetate Its demand is closely related to the demand for coatings, adhesives and textiles.

4. Methanol can be used for manufacturing Methyl formate Methyl formate can be used to produce formic acid, formamide and other fine chemical products, as well as pesticides, fungicides, fumigants, tobacco treatment agents and gasoline additives.

5. Methanol can also be used to produce methylamine, which is an important fatty amine. With liquid nitrogen and methanol as raw materials, it can be separated into monomethylamine, dimethylamine and trimethylamine through processing, and is one of the basic chemical raw materials.

6. Methanol can be combined into dimethyl carbonate, which is an environmental protection product and is used in medicine, agriculture and special industries.

7. Methanol can be synthesized into ethylene glycol, which is one of the petrochemical intermediate materials and can be used to produce polyester and antifreeze.

8. Methanol can be used to manufacture growth promoter. It can increase crop production in a large amount, keep the branches and leaves fresh, vigorous and luxuriant, and will not wither in summer. It can reduce irrigation water in a large amount, which is conducive to the growth of dry land crops.

9. Methanol can synthesize methanol protein. Methanol protein produced by microbial fermentation with methanol as raw material is called the second generation single cell protein. Compared with natural protein, it has higher nutritional value. The crude protein content is much higher than fish meal and soybean, and it contains rich amino acids, minerals and vitamins. It can replace fish meal, soybean, bone meal, meat and skimmed milk powder.^[5]

10. Methanol is used as cleaning and degreasing agent, MOS level is mainly used for discrete devices, medium and large-scale integrated circuits, and BV - Ⅲ level is mainly used for VLSI process technology.

11. It is used as analytical reagent, such as solvent, methylation reagent and chromatographic reagent. It is also used in organic synthesis.

12. Generally, methanol is a better solvent than ethanol, which can dissolve many inorganic salts. It can also be mixed with gasoline as an alternative fuel. Since the 1980s, methanol has been used to produce gasoline octane number additive methyl tert butyl ether, methanol gasoline, methanol fuel, methanol protein and other products, promoting the development of methanol production and market demand.

13. Methanol is not only an important chemical raw material, but also an excellent energy and vehicle fuel. Methanol reacts with isobutene to obtain MTBE (methyl tert butyl ether), which is a lead-free gasoline additive with high octane number and can also be used as a solvent. In addition, it can also produce olefins and propylene to solve the problem of resource shortage.

14. Methanol can be used to produce dimethyl ether, which is not only widely used in daily chemicals, pharmaceuticals, pesticides, dyes, coatings and other aspects, but also convenient and clean, with high cetane number, good power performance and less pollution. Easily pressurized as liquid, easy to store and other fuel properties. The new liquid fuel made of methanol and dimethyl ether in a certain proportion is called alcohol ether fuel. Its combustion efficiency and thermal efficiency are higher than those of liquefied gas.^[6]

Toxicological basis

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acute toxicity

LD50: 7300mg/kg (mouse by mouth); 15800mg/kg (rabbit percutaneous)

LC50: 64000ppm (inhaled by rats, 4h)

thrill

Rabbit percutaneous: 20mg (24h), moderate irritation.

Rabbit via eye: 40mg, moderate irritation.

Subacute and chronic toxicity

Rats inhaled 50mg/m three 12 hours a day, 3 months a day, and within 8~10 weeks, tracheal and bronchial mucosa damage, cerebral cortex cell malnutrition, etc. can be seen.

Mutagenicity

Microbial mutagenicity: 12% Saccharomyces cerevisiae. DNA inhibition: human lymphocytes 300mmol/L.

Teratogenicity

Inhalation of the lowest toxic dose (TCLo) of 20000ppm (7h) 6~14d after pregnancy of rats resulted in developmental abnormalities of musculoskeletal system, cardiovascular system, and urogenital system. Different doses given to rats and mice at different times after pregnancy can cause developmental malformations of endocrine system, eyes, ears, central nervous system, and craniofacial (including nose and tongue).

other

The lowest oral toxic dose (TDLo) of rats: 7500mg/kg (7-19 days of pregnancy), which has an impact on the behavior of novice rats. The lowest toxic concentration (TCLo) inhaled by rats: 20000ppm (7h) (1~22d of pregnancy), resulting in abnormal development of musculoskeletal, cardiovascular and urinary systems.^[1]

Ecological basis

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1. Irritating to respiratory tract and gastrointestinal mucosa, toxic to blood vessels and nerves, causing vasospasm, blood stasis or bleeding; It has a special selective effect on the optic nerve and retina, causing retinal necrosis due to lack of nutrition.

2. Ecotoxicity LC50: 15.4~29.4g/L (96h) (black headed fish)

3. The biodegradability MITI-I test showed that the initial concentration was 100ppm, the sludge concentration was 30ppm, and the biodegradation rate was 92% after 2 weeks.

4. In non biodegradable air, when the concentration of hydroxyl radical is 5.00 × 105/cm three The half-life of degradation is 17d (theoretical).^[1]

Health hazards

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Methanol is toxic. Industrial alcohol contains about 4% methanol. If it is used as edible alcohol by illegal persons to make fake alcohol, methanol poisoning will occur after drinking. The lethal dose of methanol is about 70ml.

The toxicity of methanol has the greatest impact on the nervous system and blood system of the human body. Its ingestion through the digestive tract, respiratory tract or skin will produce toxic reactions. Methanol vapor can damage the respiratory mucosa and vision of people. In methanol production plants, the concentration of methanol in air is limited to PC stel=50mg/m according to relevant Chinese authorities three ，PC-TWA=25mg/m three The gas mask must be worn when working on the site with methanol gas. The factory wastewater can only be discharged after treatment. The allowable content of methanol is less than 200mg/L.

The poisoning mechanism of methanol is that methanol generates formaldehyde and formic acid (commonly known as formic acid) through human metabolism, and then causes harm to human body. Initial poisoning symptoms include rapid heartbeat, abdominal pain, vomiting (vomiting), diarrhea, loss of appetite, headache, dizziness, and general weakness. First, I felt drunk. After a few hours, I felt headache, nausea, vomiting, and blurred vision. In serious cases, they may lose their sight or even lose their lives. Cause of blindness: formic acid, a metabolite of methanol, accumulates in the eye and destroys visual nerve cells. Brain nerves will also be damaged, resulting in permanent damage. When formic acid enters the blood, it will make the tissue more acidic, damage the kidney and lead to renal failure.

However, there are still many illegal businessmen who, regardless of their life safety, use industrial alcohol containing methanol to mix and sell counterfeit liquor. However, there is also very little methanol in authentic wine, which is one of the reasons for the hangover. Methanol poisoning can be detoxified with ethanol. Because methanol is oxidized into formaldehyde by alcohol dehydrogenase in the liver, and then forms formic acid. Ethanol can compete with methanol for alcohol dehydrogenase, allowing the human body time to eliminate methanol.^[7]

Poisoning symptoms

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Physical hazard: it has anesthetic effect on central nervous system; It has special selective effect on optic nerve and retina, causing pathological changes; It may cause metabolic acidosis.

Acute poisoning: slight upper respiratory tract irritation symptoms (gastrointestinal irritation symptoms after oral administration) due to short-term massive inhalation; After a period of incubation, headache, dizziness, fatigue, dizziness, drunkenness, hazy consciousness, delirium, and even coma appear. Optic nerve and retinopathy may have blurred vision, diplopia, etc., and even blindness. When metabolic acidosis occurs, carbon dioxide binding force decreases and respiration accelerates.

Chronic effects: neurasthenic syndrome, autonomic nerve dysfunction, mucous membrane irritation, vision loss, etc. Skin degrease, dermatitis, 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, wash with flowing water or physiological saline, and seek medical advice.

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 and seek medical advice.

Ingestion: drink enough warm water, induce vomiting, or use clear water or 1% sodium thiosulfate solution to wash stomach, and seek medical advice.

Methanol poisoning can usually be detoxified by ethanol. The principle is that the metabolite of methanol is toxic, so it can be detoxified by inhibiting metabolism. The metabolism of methanol and ethanol in the human body is the same enzyme, and this enzyme has more affinity with ethanol. Therefore, methanol poisoning patients can relieve methanol metabolism by drinking strong liquor (the alcohol level is usually above 60 degrees), and then expel it from the body. The formic acid produced by methanol metabolism can be neutralized by taking sodium bicarbonate.^[8]

Leakage emergency treatment

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Evacuate the personnel in the leakage contaminated area to a safe area quickly, isolate them, strictly restrict access, and cut off the fire source. It is recommended that emergency treatment personnel wear self-contained positive pressure respirators and anti-static work clothes, do not directly contact the leakage, and cut off the leakage source as far 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, or flush with a large amount of water, which is diluted and then discharged into the wastewater system. Large amount of leakage: build a dike or dig a pit to collect and cover with foam to reduce steam disaster. Use explosion-proof pump to transfer to tank car or special collector for recycling or transport to waste disposal site.^[8]

Emergency Overview

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Liquid. Highly flammable, its vapor can form explosive mixture when mixed with air. Toxic if swallowed. Toxic in contact with skin. Toxic by inhalation. Short term exposure may cause serious health damage.

GHS Hazard Category

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According to the series standards of GB 30000-2013 Specification for Classification and Labeling of Chemicals, the product is classified as follows: flammable liquid, category 2; Acute toxicity - oral, category 3; Acute toxicity - skin, category 3; Acute toxicity - inhalation, category 3; Specific target organ toxicity - single exposure, Category 1.

Storage method

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Storage

Precautions: Store in a cool and well ventilated special warehouse, away from kindling and heat sources. The warehouse temperature should not exceed 37 ℃, and the container should be kept sealed. It shall be stored separately from oxidants, acids, alkali metals, etc., and mixed storage is strictly prohibited. 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.^[1]

Transport method

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The railway transportation time limit of this product is to use the steel enterprise's own tank car for shipment, and it needs to be reported to the relevant departments 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, acids, alkali metals, 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.

Fire fighting points

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It mainly includes: insoluble foam, dry powder, carbon dioxide, sand, etc. Extinguishing method: Move the container from the fire site to an open place as far as possible. Spray water to keep the fire site container cool until the fire is extinguished. If the container in the fire site has changed color or sounds from the safety relief device, it must be evacuated immediately.