Ethylene (Eten), preparation, properties, and chemical reactions.
Ethylene (Eten), C2H4 is an organic substance of a class of alkenes. Ethylene has a double carbon-carbon bond and therefore relates to unsaturated, or unsaturated hydrocarbon.
Ethylene (Eten) – organic matter class alkenes, consisting of two atoms of carbon and four atoms of hydrogen. Ethylene has a double carbon-carbon bond and therefore relates to unsaturated, or unsaturated hydrocarbon.
The chemical formula of ethylene, C2H4, H2CCH2 rational formula, structural formula CH2=CH2. Isomers has not.
The structure of the molecule:
Ethylene – a colorless gas, without taste, with a faint odor. Lighter than air.
Ethylene is a plant hormone, i.e., low molecular weight organic substances produced by plants and has regulatory functions. It is formed in the tissues of the plant and performs in the life cycle of plants is diverse functions, including control of development of the germ, the ripening of fruits (particularly fruits), the blooming of the buds (flowering process), aging and falling of leaves and flowers, participating in plant responses to biotic and abiotic stress communication between different plant organs and between plants in the population.
Flammable and explosive.
Poorly soluble in water. But well soluble in diethyl ether and hydrocarbons.
Low toxicity, but adverse effects in humans – has a narcotic effect. The fourth class of danger.
Ethylene is the most produced organic compound in the world.
|The smell||with a faint odor|
|Aggregate state (at 20 °C and atmospheric pressure of 1 ATM.)||gas|
|Density (at 20 °C and atmospheric pressure of 1 ATM.) kg/m3||1,178|
|Density (at 0 °C and atmospheric pressure of 1 ATM.) kg/m3||1,26|
|Melting point, °C||-169,2|
|Boiling point, °C||-103,7|
|Flash point, °C||136,1|
|The auto-ignition temperature, °C||475,6|
|Critical temperature*, °C||9,6|
|Critical pressure, MPa||5,033|
|Explosive concentration of the mixture of gas with air, % by volume||from 2.75 to 36,35|
|Specific heat of combustion, MJ/kg||46,988|
|Coefficient of thermal conductivity (at 0 °C and atmospheric pressure of 1 ATM.) W/(m·K)||0,0163|
|Coefficient of thermal conductivity (at 50 °C and atmospheric pressure of 1 ATM.) W/(m·K)||0,0209|
|Molar mass, g/mol||28,05|
* at temperatures above the critical temperature the gas cannot be condensed at any pressure.
Ethylene is a chemically active substance. Since the molecule between the atoms of carbon has a double bond, then one of them, less durable, easily broken, and in place of the connection fails accession, substitution, oxidation, polymerization of the molecules.
Chemical properties of ethylene are similar to properties of other representatives of a number of alkenes. So it is characterized by the following chemical reactions:
1. catalytic hydrogenation (recovery) of ethylene:
CH2=CH2 + H2 → CH3-CH3 (kat = Ni, Pd, Pt, to).
2. galogenirovannami of ethylene:
CH2=CH2 + Br2 → CH2Br -CH2Br.
However, by heating ethylene to a temperature of 300 ° C gap double carbon-carbon bonds – the reaction of halogenation occurs by a mechanism of radical substitution:
CH2=CH2 + Br2 → CH2=CH-Br + HBr (t = 300 oC).
3. hydrohalogenation of ethylene:
CH2=CH2 + HBr → CH3-CH2Br.
4. hydration of ethylene:
CH2=CH2 + H2O → CH3-СН2ОН (H+, to).
The reaction occurs in the presence of mineral acids (sulphuric, phosphoric). As a result of this chemical reaction produces ethanol.
5. the oxidation of ethylene:
Ethylene is easily oxidized. Depending on the reaction conditions the oxidation of ethylene can be obtained in different substances: polyhydric alcohols, epoxides or aldehydes.
2CH2=CH2 + O2 → 2C2OH4 (kat = Ag, to).
The result is an epoxide.
2CH2=CH2 + O2 → 2CH3-C(O)H (kat = PdCl2, CuCl, t = 200oC ).
The result is acetaldehyde.
6. combustion of ethylene:
CH2=CH2 + 3O2 → 2CO2 + 2H2O.
As a result of combustion of ethylene is break all ties in the molecule, and the reaction products are carbon dioxide and water.
7. polymerization of ethylene:
nCH2=CH2 → (-CH2-CH2-)n (kat, to).
Ethylene get in the laboratory and in industrial scale.
Industrially, ethylene is obtained by the following chemical reactions:
1. catalytic dehydrogenation of ethane:
CH3-CH3 → CH2=CH2 + H2 (kat = Pt, Ni, Al2O3, Cr2O3, to = 400-600 °C).
Ethylene in the laboratory is the result of the following chemical reactions:
1. dehydration of ethanol:
CH3-CH2-OH → CH2=CH2 + H2O (H2SO4 (conc), to = 170).
2. negalogenizirovanny dehalogenation ethane:
CH3-CH2-Br + NaOH → CH2=CH2 + NaBr + H2O (to);
Cl-CH2-CH2-Cl + Zn → CH2=CH2 + ZnCl2.
Cl-CH2-CH2-Cl + Mg → CH2=CH2 + MgCl2.
3. partial hydrogenation of acetylene:
CH≡CH + H2 → CH2=CH2 (Pd, to).
4. dehydrohalogenating halogen derivatives of alkanes under the influence of alcohol solutions of alkalis:
CH3-CH2-Br + KOH → CH2 = CH2 + KBr + H2O.
– as a raw material in chemical industries for the organic synthesis of various organic compounds: halogen derivatives, alcohols (ethanol, ethylene glycol), vinyl acetate, dichloroethane, vinyl chloride, ethylene oxide, polyethylene, styrene, acetic acid, ethylbenzene, ethylene glycol,etc.,
– in the manufacture of polymers.
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