Contains a double bond and therefore refers to unsaturated or unsaturated hydrocarbons. Plays an extremely important role in industry and is also a phytohormone. Ethylene is the world's most produced organic compound; the total world ethylene production in 2008 was 113 million tons and continues to grow by 2-3% per year. Ethylene has a narcotic effect. The hazard class is the fourth.
Receiving
Ethylene was widely used as a monomer before World War II due to the need to obtain a high-quality insulation material that could replace polyvinyl chloride. After the development of a method for the polymerization of ethylene under high pressure and the study of the dielectric properties of the resulting polyethylene, its production began, first in Great Britain, and later in other countries.
The main industrial method for producing ethylene is the pyrolysis of liquid distillates of oil or lower saturated hydrocarbons. The reaction is carried out in tube furnaces at + 800-950 ° C and a pressure of 0.3 MPa. When using straight-run gasoline as a raw material, the ethylene yield is about 30%. Simultaneously with ethylene, a significant amount of liquid hydrocarbons, including aromatic ones, is also formed. When pyrolysis of gas oil, the yield of ethylene is about 15-25%. The highest ethylene yield - up to 50% - is achieved when saturated hydrocarbons are used as raw materials: ethane, propane and butane. Their pyrolysis is carried out in the presence of water vapor.
At release from production, during commodity accounting operations, when checking it for compliance with regulatory and technical documentation, ethylene samples are taken according to the procedure described in GOST 24975.0-89 “Ethylene and propylene. Sampling methods ". Ethylene sampling can be carried out both in gaseous and liquefied form in special samplers in accordance with GOST 14921.
Ethylene produced industrially in Russia must comply with the requirements set out in GOST 25070-2013 “Ethylene. Technical conditions ".
Production structure
Currently, in the structure of ethylene production, 64% falls on large-scale pyrolysis units, ~ 17% - on low-tonnage gas pyrolysis units, ~ 11% is gasoline pyrolysis and 8% falls on ethane pyrolysis.
Application
Ethylene is the leading product of basic organic synthesis and is used to obtain the following compounds (listed in alphabetical order):
- Dichloroethane / vinyl chloride (3rd place, 12% of the total volume);
- Ethylene oxide (2nd place, 14-15% of the total volume);
- Polyethylene (1st place, up to 60% of the total volume);
Ethylene mixed with oxygen was used in medicine for anesthesia until the mid-1980s in the USSR and the Middle East. Ethylene is a phytohormone in almost all plants; among other things, it is responsible for the dropping of needles in conifers.
Electronic and spatial structure of the molecule
Carbon atoms are in the second valence state (sp 2 -hybridization). As a result, three hybrid clouds are formed on the plane at an angle of 120 °, which form three σ-bonds with carbon and two hydrogen atoms; The p-electron, which did not participate in hybridization, forms a π-bond in the perpendicular plane with the p-electron of a neighboring carbon atom. This forms a double bond between carbon atoms. The molecule has a planar structure.
Basic chemical properties
Ethylene - chemically active substance... Since there is a double bond between the carbon atoms in the molecule, one of them, less strong, easily breaks, and at the site of the bond breaking, the molecules are added, oxidized, and polymerized.
- Halogenation:
- Hydrogenation:
- Hydrohalogenation:
- Hydration:
- Oxidation:
- Combustion:
- Polymerization (obtaining polyethylene):
Biological role
Among the best known functions of ethylene is the development of the so-called triple response in etiolated (grown in the dark) seedlings when treated with this hormone. The triple response includes three reactions: shortening and thickening of the hypocotyl, shortening of the root, and strengthening of the apical hook (sharp bending of the upper part of the hypocotyl). The response of the seedlings to ethylene is extremely important in the early stages of their development, as it promotes the penetration of the seedlings to the light.
In the commercial harvesting of fruits and vegetables, special rooms or chambers are used for ripening fruits, into the atmosphere of which ethylene is injected from special catalytic generators that produce gaseous ethylene from liquid ethanol. Typically, to stimulate ripening of fruits, a concentration of ethylene gas in the atmosphere of the chamber from 500 to 2000 ppm is used for 24-48 hours. At a higher air temperature and a higher concentration of ethylene in the air, fruits ripen faster. It is important, however, to ensure control of the carbon dioxide content in the atmosphere of the chamber, since high-temperature ripening (at temperatures above 20 degrees Celsius) or maturation at a high concentration of ethylene in the air of the chamber leads to a sharp increase in carbon dioxide emission by rapidly ripening fruits, sometimes up to 10% carbon dioxide in the air after 24 hours from the beginning of ripening, which can lead to carbon dioxide poisoning of both workers harvesting already ripe fruits and the fruits themselves.
Ethylene has been used to stimulate fruit ripening since Ancient egypt... The ancient Egyptians deliberately scratched or slightly crushed, beat off dates, figs and other fruits in order to stimulate their ripening (tissue damage stimulates the formation of ethylene by plant tissues). The ancient Chinese burned wooden incense sticks or incense candles indoors in order to stimulate the ripening of peaches (when burning candles or wood, not only carbon dioxide is released, but also partially oxidized combustion intermediates, including ethylene). In 1864, it was discovered that a leak of natural gas from street lamps caused inhibition of the growth of nearby plants in length, their twisting, abnormal thickening of stems and roots, and accelerated ripening of fruits. In 1901, Russian scientist Dmitry Nelyubov showed that the active component of natural gas causing these changes is not its main component, methane, but ethylene present in it in small amounts. Later in 1917, Sarah Dubt proved that ethylene stimulates premature leaf fall. However, it was not until 1934 that Gein discovered that plants themselves synthesize endogenous ethylene. ... In 1935, Crocker proposed that ethylene is a plant hormone responsible for the physiological regulation of fruit ripening, as well as aging of plant vegetative tissues, leaf fall and growth inhibition.
The ethylene biosynthesis cycle begins with the conversion of the amino acid methionine to S-adenosyl-methionine (SAMe) by the enzyme methionine-adenosyltransferase. Then S-adenosyl-methionine is converted to 1-aminocyclopropane-1-carboxylic acid (ACA, ACC) using the enzyme 1-aminocyclopropane-1-carboxylate synthetase (ACC synthetase). The activity of ACC synthetase limits the rate of the entire cycle; therefore, regulation of the activity of this enzyme is key in the regulation of ethylene biosynthesis in plants. The last stage of ethylene biosynthesis requires oxygen and occurs under the action of the enzyme aminocyclopropanecarboxylate oxidase (ACC oxidase), previously known as the ethylene-forming enzyme. Ethylene biosynthesis in plants is induced by both exogenous and endogenous ethylene (positive feedback). The activity of ACC synthetase and, accordingly, the formation of ethylene also increases with high levels auxins, especially indoleacetic acid, and cytokinins.
The ethylene signal in plants is perceived by at least five different families of transmembrane receptors, which are protein dimers. In particular, the ethylene receptor ETR 1 is known in Arabidopsis ( Arabidopsis). Genes encoding receptors for ethylene have been cloned from Arabidopsis and then from tomato. Ethylene receptors are encoded by a variety of genes in both the Arabidopsis genome and the tomato genome. Mutations in any of the gene family, which consists of five types of ethylene receptors in Arabidopsis and at least six types of receptors in tomato, can lead to plant insensitivity to ethylene and impairment of maturation, growth and wilting processes. DNA sequences characteristic of genes for ethylene receptors have also been found in many other plant species. Moreover, an ethylene-binding protein has been found even in cyanobacteria.
Unfavorable external factors, such as insufficient oxygen content in the atmosphere, flooding, drought, frosts, mechanical damage (injury) to the plant, attack by pathogenic microorganisms, fungi or insects, can cause an increased formation of ethylene in plant tissues. For example, during a flood, plant roots suffer from excess water and lack of oxygen (hypoxia), which leads to the biosynthesis of 1-aminocyclopropane-1-carboxylic acid in them. ACC is then transported along the pathways in the stems up to the leaves, and in the leaves is oxidized to ethylene. The resulting ethylene promotes epinastic movements, leading to mechanical shaking off of water from the leaves, as well as wilting and dropping of leaves, flower petals and fruits, which allows the plant to simultaneously get rid of excess water in the body and reduce oxygen demand by reducing the total mass of tissues.
Small amounts of endogenous ethylene are also formed in animal cells, including humans, during lipid peroxidation. A certain amount of endogenous ethylene is then oxidized to ethylene oxide, which has the ability to alkylate DNA and proteins, including hemoglobin (forming a specific adduct with the N-terminal hemoglobin valine - N-hydroxyethyl-valine). Endogenous ethylene oxide can also alkylate DNA guanine bases, which leads to the formation of the 7- (2-hydroxyethyl) -guanine adduct, and is one of the reasons for the inherent risk of endogenous carcinogenesis in all living things. Endogenous ethylene oxide is also a mutagen. On the other hand, there is a hypothesis that if it were not for the formation of small amounts of endogenous ethylene and, accordingly, ethylene oxide in the body, the rate of occurrence of spontaneous mutations and, accordingly, the rate of evolution would be much lower.
Notes
- Devanney Michael T. Ethylene (eng.) (unavailable link)... SRI Consulting (September 2009). Archived July 18, 2010.
- Ethylene (eng.) (unavailable link). WP Report... SRI Consulting (January 2010). Archived August 31, 2010.
- Gas chromatographic measurement of mass concentrations of hydrocarbons: methane, ethane, ethylene, propane, propylene, butane, alpha-butylene, isopentane in the air of the working area. Methodical instructions. MUK 4.1.1306-03 (Approved by the chief state sanitary doctor of the Russian Federation 03/30/2003)
- "Plant growth and development" V. V. Chub (unspecified) (unavailable link)... Date of treatment January 21, 2007. Archived January 20, 2007.
- "Delaying Christmas tree needle loss"
- Khomchenko G.P. §16.6. Ethylene and its homologues // Chemistry for university applicants. - 2nd ed. - M.: Higher school, 1993 .-- S. 345 .-- 447 p. - ISBN 5-06-002965-4.
- V. Sh. Feldblum. Dimerization and disproportionation of olefins. Moscow: Chemistry, 1978
- Lin, Z .; Zhong, S .; Grierson, D. (2009). “Recent advances in ethylene research”. J. Exp. Bot. 60 (12): 3311-36. DOI: 10.1093 / jxb / erp204. PMID.
- Ethylene and Fruit Ripening / J Plant Growth Regul (2007) 26: 143-159 doi: 10.1007 / s00344-007-9002-y (eng.)
Ethylene is the simplest organic compound known as alkenes. It is colorless with 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. Ethylene applications are common in industrial organic chemistry... It is produced by heating natural gas, the melting point is 169.4 ° C, boiling point is 103.9 ° C.
Ethylene: structural features and properties
Hydrocarbons are molecules that contain hydrogen and carbon. They vary greatly in terms of the number of single and double bonds and the structural orientation of each component. Ethylene is one of the simplest, but biologically and economically beneficial hydrocarbons. It is supplied in a gaseous form and is colorless and flammable. It consists of two double bonded carbon atoms with hydrogen atoms. The chemical formula is C 2 H 4. The structural form of the molecule is linear due to the presence of a double bond in the center.
Ethylene has a sweet musky odor that makes it easy to identify the substance in the air. This applies to pure gas: the smell can disappear when mixed with other chemicals.
Ethylene application diagram
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 combining 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 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 (industrial alcohol) (antifreeze, 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 the substance in question is one of the simplest hydrocarbons. However, the properties of ethylene make it biologically and economically significant.
Commercial use
Ethylene properties provide a good commercial basis for a wide variety of organic (carbon and hydrogen containing) materials. Single ethylene molecules can be combined together to form 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 for the production of styrenes is relevant in the process of creating rubber and protective packaging. In addition, it is used in the footwear industry, especially in 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 commonly produced hydrocarbons on a global scale.
Health hazard
Ethylene is a health hazard primarily because it is flammable and explosive. It can also act as a drug at low concentrations, causing nausea, dizziness, headaches, and loss of motor coordination. At higher concentrations, it acts as an anesthetic, causing unconsciousness and other irritants. All these negative points can be a cause for concern, first of all, for people who directly work with gas. The amount of ethylene most people encounter in everyday lifeusually 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 an anti-freeze liquid, and in the production of polyesters by condensation polymerization.
2) Halogenation - reactions with ethylene 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 useful as well as a valuable precursor in the synthesis of vinyl chloride.
4) Alkylation - the addition of hydrocarbons at 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 for the production of polystyrene.
5) Combustion of ethylene. The gas is produced by heating 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 does not dissolve well in water. 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 produces a flame consisting of three separate layers - an inner core - unburned gas, a blue-green layer and an outer cone, where the partially oxidized product from the premixed layer is burned in a diffusion flame. The resulting 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) The gas is not harmful and non-toxic to humans at a certain concentration (100-150 mg).
3) It is used in medicine as a pain reliever.
4) The action of ethylene slows down at low temperatures.
5) Characteristic is good penetration through most substances, such as cardboard packaging boxes, wooden and even concrete walls.
6) While it is invaluable due to 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 concentration, duration of exposure and temperature.
7) Ethylene is explosive at high concentrations.
8) Ethylene is used in glass production special purpose for the automotive industry.
9) Manufacturing of steel structures: gas is used as an oxy-fuel gas for metal cutting, welding and high speed thermal spraying.
10) Refining: Ethylene is used as a refrigerant, especially in natural gas liquefaction 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 dedicated, separate gas pipeline.
12) One of the most common products made directly from ethylene is plastic.
With another double bond.
1. Physical properties
Ethylene is a colorless gas with a faint pleasant odor. It is slightly lighter than air. It is slightly soluble in water, but it dissolves well in alcohol and other organic solvents.
2. Structure
Molecular formula C 2 H 4. Structural and electronic formulas:
3. Chemical properties
Unlike methane, ethylene is chemically quite active. It is characterized by addition reactions at the double bond site, polymerization reactions, and oxidation reactions. In this case, one of the double bonds is broken and a simple single bond remains in its place, and due to the dismissed valences, other atoms or atomic groups are added. Let's look at some examples of reactions. When ethylene is passed into bromine water (an aqueous solution of bromine), the latter is discolored as a result of the interaction of ethylene with bromine to form dibromoethane (ethylene bromide) C 2 H 4 Br 2:
As can be seen from the scheme of this reaction, it is not the replacement of hydrogen atoms with halogen atoms, as in saturated hydrocarbons, but the addition of bromine atoms at the double bond site. Ethylene also easily discolours purple aqueous solution potassium manganate KMnO 4 even at ambient temperature. Ethylene itself is oxidized to ethylene glycol C 2 H 4 (OH) 2. This process can be represented by the following equation:
- 2KMnO 4 -\u003e K 2 MnO 4 + MnO 2 + 2O
Reactions of ethylene with bromine and potassium manganate serve to open unsaturated hydrocarbons. Methane and other saturated hydrocarbons, as already noted, do not interact with potassium manganate.
Ethylene reacts with hydrogen. So, when a mixture of ethylene with hydrogen is heated in the presence of a catalyst (powder of nickel, platinum or palladium), they combine to form ethane:
Reactions in which the addition of hydrogen to a substance occurs are called hydrogenation or hydrogenation reactions. Hydrogenation reactions are of great practical importance. they are quite often used in industry. Unlike methane, ethylene burns like a scorching flame in air, since it contains more carbon than methane. Therefore, not all carbon burns off at once and its particles are very hot and glow. These carbon particles are then burned on the outside of the flame:
- C 2 H 4 + 3O 2 \u003d 2CO 2 + 2H 2 O
Ethylene, like methane, forms explosive mixtures with air.
4. Receiving
Ethylene does not occur naturally, with the exception of minor impurities in natural gas. Under laboratory conditions, ethylene is usually obtained by the action of concentrated sulfuric acid on ethanol when heated. This process can be represented by the following summary equation:
During the reaction, the elements of water are subtracted from the alcohol molecule, and the fired two valencies saturate each other with the formation of a double bond between the carbon atoms. For industrial purposes, ethylene is obtained in large quantities from petroleum cracking gases.
5. Application
IN modern industry ethylene is widely used for the synthesis of ethyl alcohol and the production of important polymeric materials (polyethylene, etc.), as well as for the synthesis of other organic substances. The property of ethylene is very interesting to accelerate the ripening of many garden and garden fruits (tomatoes, melons, pears, lemons, etc.). Using this, the fruits can be transported while still green, and then brought to a ripe state already at the point of consumption, by introducing small quantities of ethylene into the air of the warehouse.
Ethylene is used to produce vinyl chloride and polyvinyl chloride, butadiene and synthetic rubbers, ethylene oxide and polymers based on it, ethylene glycol, etc.
Notes
Sources
- F. A. Derkach "Chemistry" L. 1968
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Ethylene discovery history
Ethylene was first obtained by the German chemist Johann Becher in 1680 by the action of vitriol oil (H 2 SO 4) on wine (ethyl) alcohol (C 2 H 5 OH).
CH 3 -CH 2 -OH + H 2 SO 4 → CH 2 \u003d CH 2 + H 2 O
At first, it was identified with "combustible air", that is, with hydrogen. Later, in 1795, the Dutch chemists Deiman, Pots-van-Truswick, Bond and Lauerenburg obtained ethylene in a similar way and described it under the name "oily gas", since they discovered the ability of ethylene to add chlorine to form an oily liquid - ethylene chloride ("the oil of Dutch chemists "), (Prokhorov, 1978).
The study of the properties of ethylene, its derivatives and homologues began in the middle of the 19th century. The practical use of these compounds began with the classical studies of A.M. Butlerov and his students in the field of unsaturated compounds and especially the creation of the theory by Butlerov chemical structure... In 1860 he obtained ethylene by the action of copper on methylene iodide, establishing the structure of ethylene.
In 1901, Dmitry Nikolaevich Nelyubov grew peas in a laboratory, in St. Petersburg, but the seeds gave crooked, shortened seedlings, whose top was bent with a hook and did not bend. In the greenhouse and in the fresh air, the seedlings were even, tall, and the top in the light quickly straightened the hook. Nelyubov suggested that the factor causing the physiological effect is in the laboratory air.
At that time, the premises were lit with gas. The same gas was burning in the street lamps, and it has long been noticed that in the event of an accident in the gas pipeline, the trees standing next to the place of the gas leak turn yellow prematurely and shed their leaves.
The lighting gas contained a variety of organic matter... To remove the gas impurity, Nelyubov passed it through a heated tube with copper oxide. Pea seedlings developed normally in the "purified" air. In order to find out exactly which substance causes the response of the seedlings, Nelyubov added various components of the lamp gas in turn, and found that the addition of ethylene causes:
1) slower growth in length and thickening of the seedling,
2) "not unbending" apical loop,
3) Changing the orientation of the seedling in space.
This physiological response of the seedlings has been termed the triple response to ethylene. Peas turned out to be so sensitive to ethylene that they began to use it in bioassays to determine low concentrations of this gas. It was soon discovered that ethylene also caused other effects: leaf fall, ripening of fruits, etc. It turned out that ethylene can be synthesized by the plants themselves, i.e. ethylene is a phytohormone (Petushkova, 1986).
Physical properties ethylene
Ethylene - organic chemical compounddescribed by the formula C 2 H 4. It is the simplest alkene ( olefin).
Ethylene is a colorless gas with a faint sweet smell with a density of 1.178 kg / m³ (lighter than air), its inhalation has a narcotic effect on humans. Ethylene dissolves in ether and acetone, much less in water and alcohol. When mixed with air, forms an explosive mixture
It solidifies at –169.5 ° C, melts at the same temperature conditions. Ethene boils at –103.8 ° C. Flammable when heated to 540 ° C. The gas burns well, the flame is luminous, with a weak soot. Rounded molar mass substances - 28 g / mol. The third and fourth representatives of the ethene homologous series are also gaseous substances. The physical properties of the fifth and the following alkenes are different; they are liquids and solids.
Ethylene production
The main methods for producing ethylene:
Dehydrohalogenation of halogenated alkanes under the action of alcoholic solutions of alkalis
CH 3 -CH 2 -Br + KOH → CH 2 \u003d CH 2 + KBr + H 2 O;
Dehalogenation of dihalogenated alkane derivatives under the action of active metals
Cl-CH 2 -CH 2 -Cl + Zn → ZnCl 2 + CH 2 \u003d CH 2;
Dehydration of ethylene by heating it with sulfuric acid (t\u003e 150˚ C) or passing its vapor over the catalyst
CH 3 -CH 2 -OH → CH 2 \u003d CH 2 + H 2 O;
Dehydrogenation of ethane by heating (500С) in the presence of a catalyst (Ni, Pt, Pd)
CH 3 -CH 3 → CH 2 \u003d CH 2 + H 2.
Chemical properties ethylene
Ethylene is characterized by reactions proceeding by the mechanism of electrophilic, addition, radical substitution, oxidation, reduction, polymerization reactions.
1. Halogenation(electrophilic addition) - the interaction of ethylene with halogens, for example, with bromine, in which bromine water is discolored:
CH 2 \u003d CH 2 + Br 2 \u003d Br-CH 2 -CH 2 Br.
Ethylene halogenation is also possible upon heating (300C), in this case, the double bond does not break - the reaction proceeds according to the radical substitution mechanism:
CH 2 \u003d CH 2 + Cl 2 → CH 2 \u003d CH-Cl + HCl.
2. Hydrohalogenation - the interaction of ethylene with hydrogen halides (HCl, HBr) with the formation of halogenated alkanes:
CH 2 \u003d CH 2 + HCl → CH 3 -CH 2 -Cl.
3. Hydration - interaction of ethylene with water in the presence of mineral acids (sulfuric, phosphoric) with the formation of a saturated monohydric alcohol - ethanol:
CH 2 \u003d CH 2 + H 2 O → CH 3 -CH 2 -OH.
Among the reactions of electrophilic addition, the addition hypochlorous acid(1) reactions hydroxy- and alkoxymercuration (2, 3) (obtaining organomercury compounds) and hydroborating (4):
CH 2 \u003d CH 2 + HClO → CH 2 (OH) —CH 2 —Cl (1);
CH 2 \u003d CH 2 + (CH 3 COO) 2 Hg + H 2 O → CH 2 (OH) -CH 2 -Hg-OCOCH 3 + CH 3 COOH (2);
CH 2 \u003d CH 2 + (CH 3 COO) 2 Hg + R-OH → R-CH 2 (OCH 3) -CH 2 -Hg-OCOCH 3 + CH 3 COOH (3);
CH 2 \u003d CH 2 + BH 3 → CH 3 -CH 2 -BH 2 (4).
Nucleophilic addition reactions are characteristic of ethylene derivatives containing electron-withdrawing substituents. Among the reactions of nucleophilic addition, a special place is occupied by the addition reactions of hydrocyanic acid, ammonia, ethanol. For instance,
2 ON-CH \u003d CH 2 + HCN → 2 ON-CH 2 -CH 2 -CN.
4. oxidation. Ethylene oxidizes easily. If ethylene is passed through a potassium permanganate solution, it will become discolored. This reaction is used to distinguish between limiting and unsaturated compounds. The result is ethylene glycol
3CH 2 \u003d CH 2 + 2KMnO 4 + 4H 2 O \u003d 3CH 2 (OH) -CH 2 (OH) + 2MnO 2 + 2KOH.
When severe oxidation ethylene with a boiling solution of potassium permanganate in an acidic medium, a complete rupture of the bond (σ-bond) occurs with the formation of formic acid and carbon dioxide:
Oxidation ethylene oxygen at 200C in the presence of CuCl 2 and PdCl 2 leads to the formation of acetaldehyde:
CH 2 \u003d CH 2 + 1 / 2O 2 \u003d CH 3 -CH \u003d O.
5. hydrogenation. When rebuilding ethylene, ethane, a representative of the alkane class, is formed. The reduction reaction (hydrogenation reaction) of ethylene proceeds by a radical mechanism. The condition for the reaction is the presence of catalysts (Ni, Pd, Pt), as well as the heating of the reaction mixture:
CH 2 \u003d CH 2 + H 2 \u003d CH 3 -CH 3.
6. Ethylene enters into polymerization reaction... Polymerization is the process of formation of a high-molecular compound - a polymer - by connecting with each other using the main valences of the molecules of the initial low-molecular substance - a monomer. Ethylene polymerization occurs under the action of acids (cationic mechanism) or radicals (radical mechanism):
n CH 2 \u003d CH 2 \u003d - (- CH 2 -CH 2 -) n -.
7. Combustion:
C 2 H 4 + 3O 2 → 2CO 2 + 2H 2 O
8. Dimerization. Dimerization - the process of forming a new substance by combining two structural elements (molecules, including proteins, or particles) into a complex (dimer) stabilized by weak and / or covalent bonds.
2CH 2 \u003d CH 2 → CH 2 \u003d CH-CH 2 -CH 3
Application
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 combining 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 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 di-carbon compounds such as ethanol ( industrial alcohol), ethylene oxide ( antifreeze, polyester fibers and films), acetaldehyde and vinyl chloride. In addition to these compounds, ethylene forms ethylbenzene with benzene, 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.
Ethylene properties provide a good commercial basis for a wide variety of organic (carbon and hydrogen containing) materials. Single ethylene molecules can be combined together to form polyethylene (which means many ethylene molecules). Polyethylene is used to make plastics. Moreover, it can be used to make detergents and synthetic lubricants, which are chemicals used to reduce friction. The use of ethylene for the production of styrenes is relevant in the process of creating rubber and protective packaging. In addition, it is used in the shoe industry, especially in sports shoes, as well as in the production car tires... The use of ethylene is commercially important and the gas itself is one of the most commonly produced hydrocarbons globally.
Ethylene is used in the production of special glass for the automotive industry.