The density of ethanol liquid is 0.789 g/cm (20 C), the density of ethanol gas is 1.59kg/m, the boiling point is 78.3℃, and the melting point is-11℃. It is flammable, and its steam can form an explosive mixture with air, which can be mixed with water in any proportion. It is miscible with most organic solvents such as chloroform, ether, methanol and acetone, and its relative density is (D 15.56) 0.85438+06.
Ethanol is widely used. It can be used to make acetic acid, beverages, spices, dyes, fuels and so on. Ethanol with a volume fraction of 70%-75% is also a commonly used disinfectant in medical treatment, which is widely used in national defense industry, medical and health care, organic synthesis, food industry and industrial and agricultural production.
Ethanol and methyl ether are isomers of each other.
Ethanol (English: Ethanol, structural abbreviation: CH3CH2OH) is a kind of alcohol and the main component of wine, so it is also called alcohol, and it is commonly known as fire wine in some places. The chemical formula can also be written as C2H5OH or EtOH, and Et stands for ethyl. Ethanol, which is flammable, is a commonly used fuel, solvent and disinfectant, and is also used to prepare other compounds. Industrial alcohol contains a small amount of methanol. Medical alcohol mainly refers to ethanol with a concentration of about 75%, and also includes other concentrations of alcohol widely used in medicine. Ethanol and methyl ether are isomers.
Density: 0.78945g/cm3; (liquid) 20 degrees Celsius
Melting point:-1 14.3 degrees Celsius (158.8 kelvin)
Boiling point: 78.4℃ (35 1.6 K)
When dissolved in water: pKa = 15.9
Viscosity: 1.200 MPa sec (centipoise), 20.0℃.
Molecular dipole moment: 5.64 fc FM (1.69 d) (gas)
Refractive index: 1.5438+04
Relative density (water = 1): 0.79
Relative steam density (air = 1): 1.59.
Saturated vapor pressure (kpa): 5.33 (19℃)
ethanol
Combustion heat (kJ/mol): 1365.5
Critical temperature (℃): 243.438+0
Critical pressure (MPa): 6.38
Logarithmic value of octanol/water partition coefficient: 0.32
Flash point (℃): 12
Ignition temperature (℃): 363
Upper explosion limit% (v/v): 19.0
Lower explosive limit% (volume/volume): 3.3
Solubility: miscible with water, miscible with most organic solvents such as ether, chloroform and glycerol.
Ionization: Non-electrolyte
Colorless and transparent liquid with special fragrance (volatile), less dense than water, can be mixed with water in any proportion (generally can not be used as extractant). It is an important solvent, which can dissolve a variety of organic and inorganic substances.
Ethanol is a good solvent, which can dissolve many inorganic substances and many organic substances. Therefore, ethanol is often used to dissolve plant pigments or their medicinal components, and ethanol is also often used as a solvent for the reaction, so that both organic and inorganic substances involved in the reaction can be dissolved, the contact area can be increased, and the reaction rate can be improved. For example, in the saponification reaction of oils and fats, adding ethanol can not only dissolve sodium hydroxide, but also dissolve oils and fats, so that they can fully contact in homogeneous phase (solution of the same solvent), speed up the reaction and improve the reaction limit.
The physical properties of ethanol are mainly related to the properties of its low-carbon linear alcohol. The hydroxyl groups in the molecule can form hydrogen bonds, so the viscosity of ethanol is very high, and it is not as polar as organic compounds with similar relative molecular weight. At room temperature, ethanol is a colorless, flammable and volatile liquid with special fragrance.
When λ=589.3nm,18.35 C, the refractive index of ethanol is 1.36242, which is slightly higher than that of water.
As a solvent, ethanol is volatile and miscible with water, acetic acid, acetone, benzene, carbon tetrachloride, chloroform, ether, ethylene glycol, glycerol, nitromethane, pyridine and toluene. In addition, low-carbon aliphatic hydrocarbons such as pentane and hexane, chlorinated aliphatic hydrocarbons such as 1, 1, 1- trichloroethane and tetrachloroethylene can also be miscible with ethanol. With the increase of carbon number, the solubility of higher alcohols in water decreased obviously.
Due to the existence of hydrogen bonds, ethanol is easily deliquescent and can quickly absorb water from the air. The polarity of hydroxyl makes many ionic compounds soluble in ethanol, such as sodium hydroxide, potassium hydroxide, magnesium chloride, calcium chloride, ammonium chloride, ammonium bromide, sodium bromide and so on. Sodium chloride and potassium chloride are slightly soluble in ethanol. In addition, its nonpolar hydrocarbon group enables ethanol to dissolve some nonpolar substances, such as most essential oils and many flavor enhancers, color enhancers and medical reagents.
Folding acidity
Ethanol can't be called acid, it can't change the color of acid-base indicator, and it doesn't react with alkali. It can be said that it is not acidic.
Alcohol molecules contain polarized oxygen-hydrogen bonds, which will produce alkoxy anions and protons when ionized.
CH3CH2OH→ (reversible) CH3CH? O-+ H+
The PKA of ethanol is 15.9, which is similar to that of water.
The acidity of ethanol is very weak, but the existence of ionization equilibrium is enough to make the isotope exchange between ethanol and heavy water proceed rapidly.
CH3CH2OH+D2O→ (reversible) CH3CH2OD+HOD
Because ethanol can ionize a very small amount of hydrogen ions, it can only react with a small amount of metals (mainly alkali metals) to generate corresponding alcohol metals and hydrogen:
2CH3CH2OH +2Na→2CH3CH2ONa + H2↑
Ethanol can react with highly active metals to produce alkoxide and hydrogen.
Alcohol metal is rapidly hydrolyzed into alcohol and alkali when it meets water.
Conclusion:
(1) Ethanol can react with sodium metal to produce hydrogen, but it is not as violent as water.
(2) Active metals (potassium, calcium, sodium, magnesium and aluminum) can replace the hydrogen in the hydroxyl group of ethanol.
Folding reducibility
Ethanol is reducible and can be oxidized to acetaldehyde. The chief culprit of alcoholism is usually considered to be acetaldehyde with certain toxicity, not the alcohol drunk. take for example
2CH3CH2OH+O2→ 2CH3CHO +2H2O (provided that it is heated under the action of catalyst Cu or Ag)
In fact, ethanol first reacts with copper oxide, and then copper oxide is reduced to elemental copper. The phenomenon is that black copper oxide turns red.
Ethanol can also be oxidized by potassium permanganate, which changes from purple to colorless at the same time. Ethanol can also react with acidic potassium dichromate solution. When ethanol vapor enters the silica gel containing acidic potassium dichromate solution, it can be seen that the silica gel changes from orange red to grass green. This reaction is now used to test whether the driver is drunk.
Folding can produce esterification reaction.
Under the catalysis of concentrated sulfuric acid, ethanol can be esterified with acetic acid when heated to produce ethyl acetate (fruity).
C2H5OH+CH3COOH-concentrated H2SO4△ (reversible) →CH3COOCH2CH3+H2O (this is a substitution reaction, but the reverse reaction catalyst is dilute H2SO4 or NaOH).
Acid removes carboxyl groups, and alcohol removes hydrogen from hydroxyl groups.
Folding can react with halogen acid.
Ethanol can be replaced by hydrogen halide to produce halogenated hydrocarbon and water.
C2H5OH+HBr→C2H5Br+H2O or written as CH3 H2OH+HBR → CH3 H2BR+H-OH C2H5OH+HX → C2H5X+H2O.
Note: This reaction is usually carried out by heating the mixture of sodium bromide and sulfuric acid and ethanol. Therefore, reddish-brown gas is often produced.
Folding will produce oxidation reaction.
(1) combustion: emit light blue flame, produce carbon dioxide and water (steam), and release a lot of heat. When it is not completely burned, it will also produce carbon monoxide with a yellow flame and release heat.
Complete combustion: C2H5OH+3O2-ignition →2CO2+3H2O
Incomplete combustion: 2c2h5oh+5o2-ignition →2CO2+2CO+6H2O
(2) Catalytic oxidation: under heating and in the presence of catalyst (copper or silver).
2cu+O2- heating →2CuO
C2H5OH+CuO→CH3CHO+Cu+H2O
That is, the essence of catalytic oxidation (with Cu as catalyst)
General formula: 2ch3ch2oh+O2-Cu or Ag→2CH3CHO+2H2O (industrial acetaldehyde)
Ethanol is also oxidized by the mixture of concentrated sulfuric acid and potassium permanganate, which will burn. (Remember to inject acid into alcohol, and the ratio of acid to alcohol is 1:3)
Folding can occur elimination reaction and dehydration reaction.
Ethanol can be dehydrated under the catalysis of concentrated sulfuric acid and high temperature, and the products are different at different temperatures.
(1) elimination (intramolecular dehydration) When preparing ethylene (170℃ concentrated sulfuric acid), broken porcelain pieces (or zeolite) should be added to the flask to avoid boiling.
C2H5OH→CH2=CH2↑+H2O
(2) Condensation (intermolecular dehydration) produces diethyl ether (concentrated sulfuric acid, 130℃- 140℃)
2C2H5OH →C2H5OC2H5+ H2O (this is a substitution reaction)
Dehydrogenation reaction; When ethanol vapor passes through a dehydrogenation catalyst such as copper, silver, nickel or copper-chromium oxide at high temperature, it is dehydrogenated to form aldehydes.
Widely used in medical disinfection [75% (volume fraction) ethanol solution is commonly used in medical disinfection]
Generally, 95% alcohol is used for disinfection of instruments; 70~75% alcohol is used for sterilization, for example, 75% alcohol can kill Escherichia coli, Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa and so on. Within one minute at room temperature (25C); Alcohol with lower concentration is used to lower body temperature and promote local blood circulation. However, studies have shown that ethanol can not kill bacterial spores, nor can it kill hepatitis viruses (such as hepatitis B virus). Therefore, ethanol can only be used for general disinfection, which can not meet the sterilization standard!
Ethanol can also be used in food, such as wine. Because it can be used as a good organic solvent, Chinese medicine practitioners use it to take Chinese medicine to dissolve most of the organic components in Chinese medicine.
The role of alcohol in the use of traditional Chinese medicine: 1. Alcohol can act as a medicine. The ancients said that "wine is the power of all drugs", and alcohol can make the efficacy of drugs from the outside to the inside, so as to better play the role of drugs for regulating qi and promoting blood circulation, and tonic without stagnation; 2. Alcohol contributes to the precipitation of effective components of drugs, and many components of traditional Chinese medicine are easily soluble in alcohol; 3. Anti-corrosion effect.
pharmacological action
Widely used in medical disinfection [75% (volume fraction) ethanol solution is commonly used in medical disinfection]
Generally, 95% alcohol is used for disinfection of instruments; 70~75% alcohol is used for sterilization, for example, 75% alcohol can kill Escherichia coli, Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa and so on. Within one minute at room temperature (25C); Alcohol with lower concentration is used to lower body temperature and promote local blood circulation. However, studies have shown that ethanol can not kill bacterial spores, nor can it kill hepatitis viruses (such as hepatitis B virus). Therefore, ethanol can only be used for general disinfection, which can not meet the sterilization standard!
Ethanol can also be used in food, such as wine. Because it can be used as a good organic solvent, Chinese medicine practitioners use it to take Chinese medicine to dissolve most of the organic components in Chinese medicine.
The role of alcohol in the use of traditional Chinese medicine: 1. Alcohol can act as a medicine. The ancients said that "wine is the power of all drugs", and alcohol can make the efficacy of drugs from the outside to the inside, so as to better play the role of drugs for regulating qi and promoting blood circulation, and tonic without stagnation;
2. Alcohol contributes to the precipitation of effective components of drugs, and many components of traditional Chinese medicine are easily soluble in alcohol; 3. Anti-corrosion effect.