Application of ethylene. Properties of ethylene

Ethylene is the simplest of organic compounds known as alkenes. It is a colorless flammable gas that has a sweetish taste and smell. Natural sources include natural gas and oil, it is also a natural hormone in plants in which it inhibits growth and promotes fruit ripening. The use of ethylene is a common phenomenon in industrial organic chemistry. It is produced by heating natural gas, the melting point is 169.4 ° C, boiling - 103, 9 ° C.

Ethylene: structural features and properties

Hydrocarbons are molecules containing hydrogen and carbon. They vary greatly in terms of the number of single and double bonds and the structural orientation of each component. One of the simplest, but biologically and economically advantageous hydrocarbons is ethylene. It is supplied in a gaseous form, is colorless and flammable. It consists of two double bonded carbon atoms with hydrogen atoms. The chemical formula has the form C ₂ H ₄ . The structural form of the molecule is linear because of the presence of a double bond in the center.
Ethylene has a sweetish musky odor that makes it easy to identify a substance in the air. This applies to gas in pure form: the smell can disappear when mixed with other chemicals.

The scheme of application of ethylene

Ethylene is used in two main categories: as a monomer from which large carbon chains are built, and as a starting material for other two-carbon compounds. Polymerisations are repeated combinations of many small ethylene molecules into larger ones. This process occurs at high pressures and temperatures. The fields of application of ethylene are numerous. Polyethylene is a polymer that is used especially massively in the production of packaging films, wire coatings and plastic bottles. Another use of ethylene as a monomer relates to the formation of linear α-olefins. Ethylene is the starting material for the preparation of a number of two-carbon compounds, such as ethanol (technical alcohol), ethylene oxide (antifreeze, polyester fibers and films), acetaldehyde and vinyl chloride. In addition to these compounds, ethylene with benzene forms ethylbenzene, which is used in the production of plastics and synthetic rubber. The substance under consideration is one of the simplest hydrocarbons. However, the properties of ethylene make it biologically and economically significant.

Commercial use

The properties of ethylene provide a good commercial basis for a large amount of organic (carbon-containing and hydrogen-containing) materials. Single ethylene molecules can be joined together to produce polyethylene (which means many ethylene molecules). Polyethylene is used for the manufacture of plastics. In addition, it can be used for the manufacture of detergents and synthetic lubricants, which are chemicals used to reduce friction. The use of ethylene to produce styrene is important in the process of creating rubber and protective packaging. In addition, it is used in the shoe industry, especially with regard to sports shoes, as well as in the production of automobile tires. The use of ethylene is commercially important, and the gas itself is one of the most frequently produced hydrocarbons on a global scale.

Danger to health

Ethylene poses a health hazard primarily because it is highly flammable and explosive. It can also act as a drug at low concentrations, causing nausea, dizziness, headaches and loss of movement coordination. At higher concentrations, it acts as an anesthetic, causing loss of consciousness, insensitivity to pain and other irritants. All these negative aspects can be a cause for concern primarily for people directly working with gas. The amount of ethylene that most people encounter in everyday life is usually relatively small.

Ethylene Reactions

1) Oxidation. This is the addition of oxygen, for example, in the oxidation of ethylene to ethylene oxide. It is used in the production of ethylene glycol (1,2-ethanediol), which is used as a non-freezing liquid and in the production of polyesters by condensation polymerization.

2) Halogenation - reactions with ethylene of fluorine, chlorine, bromine, iodine.

3) Chlorination of ethylene in the form of 1,2-dichloroethane and subsequent conversion of 1,2-dichloroethane to vinyl chloride monomer. 1,2-dichloroethane is a useful organic solvent, and is also a valuable precursor in the synthesis of vinyl chloride.
4) Alkylation is the addition of hydrocarbons over a double bond, for example, the synthesis of ethylbenzene from ethylene and benzene, followed by conversion to styrene. Ethylbenzene is an intermediate for the production of styrene, one of the most widely used vinyl monomers. Styrene is a monomer used for the production of polystyrene.

5) Combustion of ethylene. Gas is obtained by heating ethyl alcohol and concentrated sulfuric acid.

6) Hydration is a reaction with the addition of water to a double bond. The most important industrial application of this reaction is the conversion of ethylene to ethanol.

Ethylene and combustion

Ethylene is a gas without color, which is poorly soluble in water. Combustion of ethylene in the air is accompanied by the formation of carbon dioxide and water. In pure form, the gas burns with a light diffusion flame. Mixed with a small amount of air, it gives a flame consisting of three separate layers - an inner core - unburned gas, a blue-green layer and an outer cone, where a partially oxidized product from a premixed layer burns in a diffusion flame. The resultant flame shows a complex series of reactions, and if more air is added to the gas mixture, the diffusion layer gradually disappears.

Useful facts

1) Ethylene is a natural plant hormone, it affects the growth, development, maturation and aging of all plants.

2) Gas is not harmful and is not toxic to humans in a certain concentration (100-150 mg).

3) It is used in medicine as an anesthetic.

4) The effect of ethylene slows down at low temperatures.

5) A characteristic property is a good penetrating power through most substances, for example through cardboard packaging boxes, wooden and even concrete walls.

6) While it is invaluable due to its ability to initiate the maturation process, it can also be very harmful to many fruits, vegetables, flowers and plants, speeding up the aging process and reducing the quality of the product and its shelf life. The degree of damage depends on the concentration, duration of exposure and temperature.

7) Ethylene is explosive at high concentrations.

8) Ethylene is used in the production of special purpose glass for the automotive industry.

9) Manufacturing of metal structures: gas is used as an oxygen-fuel gas for cutting metal, welding and high speed of thermal spraying.

10) Refining: ethylene is used as a coolant, especially in the liquefaction of natural gas.

11) As mentioned earlier, ethylene is a very reactive substance, in addition, it also very easily ignites. For safety reasons, it is usually transported by a special separate gas pipeline.

12) One of the most common products made directly from ethylene is plastic.