Ethane, preparation, properties, and chemical reactions.
Ethane, C2H6 – organic substance class alkanes. In nature, found in natural gas extracted from gas and gas condensate fields in oil and gas. Is also formed in the cracking of petroleum products.
Ethan (lat. ethanum) – organic substance class alkanes, consisting of two carbon atoms and six hydrogen atoms.
The chemical formula of ethane C2H6, rational formula H3CCH3. Isomers has not.
The structure of the molecule:
Ethane is a colourless gas, without taste and smell.
In nature, found in natural gasextracted from gas and gas condensate fields in oil and gas. For the isolation of natural and associated petroleum gas produced by cleaning and separation of gas.
Is also formed in the cracking of petroleum products., including shale oil.
Also contained in shale gas and liquefied gas (liquefied natural gas).
Flammable and explosive.
Not soluble in water and other polar solvents. But soluble in some nonpolar organic substances (methanol, acetone, benzene, carbon tetrachloride, diethyl ether, etc.).
Low toxicity, but adverse effects in humans – has a narcotic effect. The fourth class of danger.
|Aggregate state (at 20 °C and atmospheric pressure of 1 ATM.)||gas|
|Density (at 20 °C and atmospheric pressure of 1 ATM.) kg/m3||1,2601|
|Density (at 0 °C and atmospheric pressure of 1 ATM.) kg/m3||1,342|
|Density (at boiling point and atmospheric pressure 1 ATM.) kg/m3||544|
|Melting point, °C||-182,81|
|Boiling point, °C||-88,63|
|The auto-ignition temperature, °C||472|
|Critical temperature*, °C||32,18|
|Critical pressure, MPa||4,8714|
|Critical specific volume, m3/kg||4891·10-6|
|Explosive concentration of the mixture of gas with air, % by volume||from 3.2 to 12.5|
|Specific heat of combustion, MJ/kg||47,5|
|Coefficient of thermal conductivity (at 0 °C and atmospheric pressure of 1 ATM.) W/(m·K)||0,018|
|Coefficient of thermal conductivity (at 20 °C and atmospheric pressure of 1 ATM.) W/(m·K)||0,0206|
|Molar mass, g/mol||30,07|
* at temperatures above the critical temperature the gas cannot be condensed at any pressure.
Ethane difficult chemical reactions. In normal conditions does not react with concentrated acids, melted and concentrated alkalis, alkali metals, Halogens (except fluorine), potassium permanganate and potassium dichromate in an acidic medium.
Chemical properties of ethane similar to the properties of other representatives of a number of alkanes. So it is characterized by the following chemical reactions:
1. catalytic dehydrogenation of ethane:
CH3-CH3 → CH2=CH2 + H2 (kat = Pt, Ni, Al2O3, Cr2O3, to = 400-600 °C).
2. galogenirovannami ethane:
CH3-CH3 + Br2 → CH3-CH2Br + HBr (hv or increased to);
CH3-CH3 + I2 → CH3-CH2I + HI (hv or increased to).
The reaction is self-perpetuating. A molecule of bromine or iodine under the action of light decomposes to the radicals, then they attack molecules of ethane, taking from them an atom of hydrogen, this produces free ethyl CH3-CH2·, which collide with molecules of bromine (iodine), destroying them and forming new radicals of iodine or bromine:
Br2 → Br·+ Br· (hv); – initiation reactions of halogenation;
CH3-CH3 + Br· → CH3-CH2· + HBr; – the chain growth reactions of halogenation;
CH3-CH2· + Br2 → CH3-CH2Br + Br·;
CH3-CH2· + Br· → CH3-CH2Br; – open circuit reactions of halogenation.
Galogenirovannami is one of the substitution reactions. First halogenides least gidrirovanny carbon atom (atom is tertiary, then secondary, primary atoms halogenide least). Galogenirovannami ethane takes place in stages – one stage is replaced by one hydrogen atom.
CH3-CH3 + Br2 → CH3-CH2Br + HBr (hv or increased to);
CH3-CH2Br + Br2 → CH3-CHBr2 + HBr (hv or increased to);
Galogenirovannami will happen next, until you have replaced all the atoms of hydrogen.
3. nitration of ethane:
CH3-CH3 + HONO2 (dilute) → CH3-C(NO2)H2 + H2O (increased to).
4. the oxidation (combustion) ethane:
With excess oxygen:
2C2H6 + 7O2 → 4CO2 + 6H2O.
Burns with a colorless flame.
If there is insufficient oxygen instead of carbon dioxide (CO2) is a carbon monoxide (co), with a small number of finely dispersed oxygen is released and carbon (in various forms, including in the form of graphene, fullerenes , etc.) or a mixture thereof.
5. sulfochlorinated ethane:
C2H6 + SO2 + Cl2 → C2H5-SO2Cl + … (hv).
6. sulfookislenie ethane:
2C2H6 + 2SO2 + O2 → 2C2H5-ЅО2ОН (increased to).
Obtaining ethane in industry and the laboratory. The chemical reaction equation of obtaining ethane:
As Ethan in sufficient quantity contained in natural gas (up to 30% and more) oil and gas and stands out from the cracking of petroleum products, it does not get artificially. It is isolated in the purification and separation of natural gas, associated gas and oil by distillation.
Ethan in the laboratory is the result of the following chemical reactions:
1. hydrogenation of unsaturated hydrocarbons, e.g. ethylene (Eten):
CH2=CH2 + H2 → CH3-CH3 (kat = Ni, Pt or Pd, increased to).
2. recovery halogenoalkanes:
C2H5I + HI → C2H6 + I2 (increased to);
C2H5Br + H2 → C2H6 + HBr.
3. halogenoalkanes interaction with the metallic alkali metal, e.g., sodium (reaction furca):
2CH3Br + 2Na → CH3-CH3 + 2NaBr;
2CH3Cl + 2Na → CH3-CH3 + 2NaCl.
The essence of this reaction is that two molecules halogenoalkane contact one, reacting with alkali metal.
4. alkaline melting of salts of monobasic organic acids
C2H5-COONa + NaOH → C2H6 + Na2CO3 (increased to).
– as a raw material in the chemical industry for the production of mainly ethylene (étain SNCF).
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