Bright representative of unsaturated hydrocarbons - ethene (ethylene).Physical Properties: colorless, flammable gas, explosive mixture with oxygen and air.The major amount of ethylene derived from petroleum for the subsequent synthesis of organic compounds (mono- and dihydric alcohols, polymers, acetic acid and other compounds).
homologous series of ethylene, sp2-hybridization
hydrocarbons, similar in structure and properties with ethene are called alkenes.Historically entrenched another term for this group - olefins.The general formula CnH2n reflects the composition of the entire class of substances.Its first representative - ethylene molecule in which carbon atoms form not three but only two õ-due to hydrogen.Alkenes - unsaturated or unsaturated compounds of the formula C2H4.Mix in the form of energy and only 2 1 p- and s-electron cloud of an atom of carbon, formed just three õ-connection.This condition is called sp2-hybridization.The fourth valence of carbon is stored in the molecule occurs π-bond.In the structural formula structural feature is reflected.But symbols to indicate different types of communication schemes are usually used the same - dashes or dots.The structure of ethylene determines its active interaction with substances of different classes.Accession water and other particles occurs due to rupture of unstable π-bond.Freed valence electrons are saturated by oxygen, hydrogen, halogen.
Ethylene: physical properties of matter
Eten under normal conditions (atmospheric pressure and a temperature of 18 ° C) - a colorless gas.He has a sweet (essential) odor, his breathing has a narcotic effect on people.Cures at -169,5 ° C, melted at the same temperature conditions.Boils ethene at -103,8 ° C.Ignites when heated to 540 ° C.Gas burns well, the flame luminous, with a faint soot.Ethylene was dissolved in ether and acetone, considerably less - in water and alcohol.Rounded molar mass of the substance - 28 g / mol.The third and fourth representatives of the homologous series of ethene - also gaseous substances.Physical properties of the fifth and following alkenes differ, they are liquids and solids.
Preparation and properties of ethylene
German chemist Johann Becher accidentally used alcohol in experiments with concentrated sulfuric acid.Thus ethene was first obtained in the laboratory (1680).In the middle of the XIX century AMButlerov gave the title compound ethylene.Physical properties and chemical reactions have also been described by the famous Russian chemist.Butlerov proposed the structural formula, reflecting the structure of matter.Process for its preparation in the laboratory:
- Catalytic hydrogenation of acetylene.
- dehydrohalogenation chloroethane by reaction with a concentrated alcoholic solution of a strong base (alkali) with heating.
- elimination of water from the molecules of ethyl alcohol (dehydration).Reaction takes place in the presence of sulfuric acid.Its equation: H2C-CH2-OH → H2C = CH2 + H2O
industrial production of:
- refining - cracking and pyrolysis of hydrocarbons;
- dehydrogenation of ethane in the presence of a catalyst.H3C-CH3 → H2C = CH2 + H2
structure ethylene explains his typical chemical reactions - atoms attaching particles C, which are located at the double bond:
- Halogenation and gidrogalogenirovanie.The products of these reactions are halogenated.
- Hydrogenation (hydrogen saturation), production of ethane.
- oxidation to ethylene glycol diol.Its formula: OH-H2C-CH2-OH.
- polymerization scheme: n (H2C = CH2) → n (-H2C-CH2-).
Fractional distillation of crude oil in large quantities produce ethylene.The physical properties, structure, chemical nature of the material allows use it in the production of ethyl alcohol, halogen derivatives, alcohols, oxides, acetic acid, and other compounds.Eten - monomer polyethylene, as well as the parent compound for polystyrene.
Dichloroethane which was prepared from ethene and chlorine, a good solvent is used in the manufacture of polyvinyl chloride (PVC).Polyethylene low and high pressure produced film, pipes, dishes, polystyrene - Cases for CD-ROM drive and other details.PVC - is the foundation of linoleum, raincoats.In agriculture, ethene processed fruit before harvest to ripen.