Ethylene is the simplest of the organic compounds known as alkenes. It is a colorless flammable gas with a sweetish taste and smell. Natural sources include natural gas and oil, it is also a natural hormone in plants where it inhibits growth and promotes fruit ripening. The use of ethylene is common in industrial organic chemistry. It is produced by heating natural gas, melting point is 169.4°C, boiling point is 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 beneficial hydrocarbons is ethylene. It is supplied in gaseous form, is colorless and flammable. It consists of two double bonded carbon atoms with hydrogen atoms. The chemical formula is C2H4. The structural form of the molecule is linear due to the presence of a double bond in the center.
Ethylene has a sweetish musky odor that makes it easy toidentify the substance in the air. This applies to gas in its pure form: the smell may disappear when mixed with other chemicals.
Ethylene application scheme
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. Polymerizations are repeated combinations of many small ethylene molecules into larger ones. This process takes place at high pressures and temperatures. The applications for ethylene are numerous. Polyethylene is a polymer that is used especially in large quantities in the production of packaging films, wire coatings and plastic bottles. Another use of ethylene as a monomer concerns 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 in question 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 number of organic (containing carbon and hydrogen) materials. Single ethylene molecules can bejoined together to make polyethylene (which means many ethylene molecules). Polyethylene is used to make plastics. In addition, it can be used to make detergents and synthetic lubricants, which are chemicals used to reduce friction. The use of ethylene to obtain styrenes is relevant in the process of creating rubber and protective packaging. In addition, it is used in the shoe industry, especially sports shoes, as well as in the production of car tires. The use of ethylene is commercially important, and the gas itself is one of the most commonly produced hydrocarbons on a global scale.
He alth hazard
Ethylene is a he alth hazard primarily because it is flammable and explosive. It can also act like a drug at low concentrations, causing nausea, dizziness, headaches, and incoordination. At higher concentrations, it acts as an anesthetic, causing unconsciousness, insensitivity to pain and other stimuli. All these negative aspects can be a cause for concern in the first place for people directly working with gas. The amount of ethylene that most people encounter in their daily lives 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 inin the production of ethylene glycol (1, 2-ethanediol), which is used as an antifreeze liquid and in the production of polyesters by condensation polymerization.
2) Halogenation - reactions with ethylene of fluorine, chlorine, bromine, iodine.
3) Chlorination of ethylene as 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 - the addition of hydrocarbons to the 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 to make polystyrene.
5) Combustion of ethylene. The 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 colorless gas that is poorly soluble in water. The combustion of ethylene in air is accompanied by the formation of carbon dioxide and water. In its 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 the partially oxidized productfrom the premixed layer burn in a diffusion flame. The resulting flame shows a complex series of reactions, and as 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) The gas is not harmful and non-toxic to humans in a certain concentration (100-150 mg).
3) It is used in medicine as a pain reliever.
4) Ethylene slows down at low temperatures.
5) Characteristic property is good penetration through most substances, such as cardboard packaging boxes, wooden and even concrete walls.
6) While it is invaluable for its ability to initiate the ripening process, it can also be very harmful to many fruits, vegetables, flowers and plants, accelerating the aging process and reducing product quality and 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 manufacture of special glass for the automotive industry.
9) Steel fabrication: The gas is used as oxy-fuel gas for metal cutting, welding and high speed thermal spraying.
10) Refining: Ethylene is usedas a refrigerant, especially in LNG plants.
11) As mentioned earlier, ethylene is a very reactive substance, in addition, it is also very flammable. For safety reasons, it is usually transported through a special separate gas pipeline.
12) One of the most common products made directly from ethylene is plastic.
