What properties are characteristic of ethylene. L.I. Popova, Chemistry Teacher (g

Characteristics and physical properties of Ethena

Definition

Ethen (ethylene) - colorless combustible gas (the structure of the molecule is shown in Fig. 1), which has a weak odor. Little soluble in water.

Ethen (ethylene) is a colorless combustible gas (the structure of the molecule is shown in Fig. 1), which has a weak odor. Little soluble in water. It is well soluble in diethyl ether and hydrocarbons.

Fig. 1. The structure of ethylene molecule.

Table 1. Physical properties of Ethena.

Getting Ethena

In industrial volumes, ETEN is obtained by refining oil: cracking and dehydrogenation of ethane. Laboratory methods for producing ethylene are presented

- Dehydration ethanol

CH 3 -CH 2 -OH → CH 2 \u003d CH 2 + H 2 O (H 2 SO 4 (CONC), T O \u003d 170).

- Dehydrogaloenirovaniyaonogalogenenthane

CH 3 -CH 2 -BR + NaOh Alcohol → CH 2 \u003d CH 2 + NABR + H 2 O (T O).

- Degalogenation of Digohyethana

CH 2 -CH 2 -Cl + Zn (Mg) → CH 2 \u003d CH 2 + ZnCl 2 (MgCl 2);

- incomplete hydrogenation of acetylene

CH≡CH + H 2 → CH 2 \u003d CH 2 (PD, T O).

Chemical properties of Ethena

Ethen is a very reactive connection. All chemical transformations of ethylene proceed with splitting:

1. p-connection C-C (accession, polymerization and oxidation)

• hydrogenation

CH 2 \u003d CH 2 + H 2 → CH 3 -CH 3 (Kat \u003d Pt).

• haloiding

CH 2 \u003d CH 2 + BR 2 → BRCH-CHBR.

• hydroalogenation

CH 2 \u003d CH 2 + H-CL → H 2 C-CHCl.

• hydration

CH 2 \u003d CH 2 + H-OH → CH 3 -CH 2 -OH (H +, T O).

• polymerization

nCH \u200b\u200b2 \u003d CH 2 → - [- CH 2 -CH 2 -] - N (Kat, T O).

• oxidation

CH 2 \u003d CH 2 + 2KMNO 4 + 2KOH → HO-CH 2 -CH 2 -OH + 2K 2 MNO 4;

2ch 2 \u003d CH 2 + O 2 → 2C 2 OH 4 (EPOXID) (KAT \u003d AG, T O);

2CH 2 \u003d CH 2 + O 2 → 2CH 3 -C (O) H (Kat \u003d PDCl 2, CUCl).

1. connections with SP 3 -N (in an allyl position)

CH 2 \u003d CH 2 + CL 2 → CH 2 \u003d CH-CL + HCl (T O \u003d 400).

1. Break all connections

C 2 H 4 + 2O 2 → 2CO 2 + 2H 2 O.

Application Ethena

The main direction of the use of ethylene is an industrial organic synthesis of such compounds like halogen derivatives, alcohols (ethanol, ethylene glycol), acetic aldehyde, acetic acid, et al. In addition, this compound in the production of polymers.

Examples of solving problems

Example 1.

The task	As a result of the joining of iodine to ethylene, 98.7 g of iodine production was obtained. Calculate the mass and amount of ethylene substance taken to reaction.
Decision	Write an iodine joining equation to ethylene: H 2 C \u003d CH 2 + I 2 → IH 2 C - CH 2 I. As a result of the reaction, Iodocol production was formed - diodeodetan. Calculate its amount of substance (molar mass is equal to - 282 g / mol): n (C 2 H 4 i 2) \u003d m (C 2 H 4 i 2) / m (C 2 H 4 i 2); n (C 2 H 4 i 2) \u003d 98.7 / 282 \u003d 0.35 mol. According to the reaction equation N (C 2 H 4 i 2): n (C 2 H 4) \u003d 1: 1, i.e. n (C 2 H 4 i 2) \u003d n (C 2 H 4) \u003d 0.35 mol. Then the mass of ethylene will be equal (molar mass - 28 g / mol): m (C 2 H 4) \u003d n (C 2 H 4) × M (C 2 H 4); m (C 2 H 4) \u003d 0.35 × 28 \u003d 9.8 g
Answer	The mass of ethylene is 9.8 g, the amount of ethylene substance is 0.35 mol.

Example 2.

The task	Calculate the volume of ethylene given to normal conditions, which can be obtained from the technical ethyl alcohol C 2 H 5 OH weighing 300 g. We note that the technical alcohol contains impurities, the mass fraction of which is 8%.
Decision	Write the equation of the ethyl alcohol production reaction equation: C 2 H 5 OH (H 2 SO 4) → C 2 H 4 + H 2 O. We find a mass of pure (without impurities) of ethyl alcohol. To do this, first calculate its mass fraction: ω pure (C 2 H 5 OH) \u003d Ω IMPURE (C 2 H 5 OH) - Ω IMPURITY; Ω Pure (C 2 H 5 OH) \u003d 100% - 8% \u003d 92%. m PURE (C 2 H 5 OH) \u003d M IMPURE (C 2 H 5 OH) × Ω Pure (C 2 H 5 OH) / 100%; m PURE (C 2 H 5 OH) \u003d 300 × 92/100% \u003d 276 We define the amount of substance of ethyl alcohol (molar weight - 46 g / mol): n (C 2 H 5 OH) \u003d M (C 2 H 5 OH) / M (C 2 H 5 OH); n (C 2 H 5 OH) \u003d 276/46 \u003d 3.83 mol. CONSUIGAININEMINEMENTNEMENTN (C 2 H 5 OH): N (C 2 H 4) \u003d 1: 1, i.e. n (C 2 H 5 OH) \u003d n (C 2 H 4) \u003d 3.83 mol. Then the volume of ethylene will be equal to: V (C 2 H 4) \u003d n (C 2 H 4) × V m; V (C 2 H 4) \u003d 3.83 × 22,4 \u003d 85.792 l.
Answer	Ethylene volume is 85.792 liters.

With a different double bond.

1. Physical properties

Ethylene is a colorless gas with a weak pleasant smell. It is a little easier. In water, there is little soluble, and in alcohol and other organic solvents it dissolves well.

2. Building

Molecular formula C 2 H 4. Structural and electronic formula:

3. Chemical properties

Unlike methane, ethylene is chemically quite active. It is characterized by the reaction of attachment at the place of double bond, the reaction of polymerization and oxidation reaction. At the same time, one of the double ties is broken and a simple single bond remains in its place, and due to the dismissed valences, other atoms or atomic groups are attached. Consider this on examples of some reactions. When ethylene passing into bromine water (aqueous solution of bromine), the latter is discolored by the result of the interaction of ethylene with bromine to form a dibrometan (ethylene bromide) C 2 H 4 BR 2:

As can be seen from the scheme of this reaction, there is no replacement of hydrogen atoms atoms at the halogen atoms, as in saturated hydrocarbons, and the addition of bromine atoms at the dual connection site. Ethylene easily discoloring also purple color aquatic solution KMNO 4 potassium manganate even at normal temperature. The same ethylene is oxidized in ethylene glycol C 2 H 4 (OH) 2. This process can be depicted by the following equation:

• 2kmno 4 -\u003e k 2 MNO 4 + MNO 2 + 2O

The reactions of the interaction of ethylene with bromine and manganate of potassium are served to open unsaturated hydrocarbons. Methane and other saturated hydrocarbons, as already noted, the potassium manganate does not interact.

Ethylene enters the reaction with hydrogen. So, when a mixture of ethylene with hydrogen is heated in the presence of a catalyst (nickel powder, platinum or palladium), then they are combined with the formation of ethane:

The reactions in which hydrogen is attached to the substance are called hydrogenation or hydrogenation reactions. Hydrogenation reactions have a large practical value. They are quite often used in industry. In contrast to methane, ethylene burns on the air by a tattensive flame, since it contains more carbon than methane. Therefore, not all carbon burns immediately and the particles are strongly split and shine. These carbon particles are then burned in the outer part of the flame:

• C 2 H 4 + 3O 2 \u003d 2CO 2 + 2H 2 O

With air ethylene, like methane, forms explosive mixtures.

4. Receipt

In nature, ethylene does not occur, with the exception of minor impurities in natural gas. In laboratory conditions, ethylene is usually obtained under the action of concentrated sulfuric acid on ethyl alcohol when heated. This process can be depicted by the following total equation:

During the reaction from the alcohol molecule, water elements are subdued, and two valence is fired at each other with the formation of a double bond between carbon atoms. For industrial purposes, ethylene is obtained in large quantities of oil cracking gases.

5. Application

In the modern industry, ethylene is used quite widely for the synthesis of ethyl alcohol and the production of important polymeric materials (polyethylene et al.)., As well as for the synthesis of other organic substances. Very interesting, the nature of ethylene accelerate the ripening of many garden and garden fruits (tomatoes, melons, pears, lemons, etc.). Using it, the fruits can be transported still to green, and then bring them to a ripe state at the place of consumption, introducing small amounts of ethylene into the air of storage rooms.

From ethylene 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

? in ? Phytoogormons

? in ? Hydrocarbons

The history of the opening of ethylene

Ethylene was first obtained by the German chemist Johann Becher in 1680 under the action of vagne oil (H 2 SO 4) on the 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

Initially, he was identified with the "combustible air", i.e. with hydrogen. Later, in 1795, the Dutch chemists Deimen, Pots-Wan Coward, Bond and Laerenburg and Laerenburg and described in the same way, were described as a "massable gas", as they found the ability of ethylene to connect chlorine to the formation of an oil liquid - ethylene chloride ("Dutch oil Chemists "), (Prokhorov, 1978).

The study of the properties of ethylene, its derivatives and homologues began from the middle of the XIX century. The beginning of the practical use of these compounds was laid classical studies A.M. Butlerova and his students in the field of unsaturated compounds and especially the creation of bootler theory chemical structure. In 1860, he received ethylene with the action of copper on iodide methylene, setting the structure of ethylene.

In 1901, Dmitry Nikolaevich Nelyubov grown peas in the laboratory, in St. Petersburg, but the seeds gave twist, shortened seedlings, whose tops were bent off and did not bend. In the greenhouse and in the fresh air, the seedlings were smooth, tall, and the top in the light quickly straightened the hook. Dislike suggested that the factor that causes the physiological effect is in the air of the laboratory.

At that time, the premises were illuminated with gas. In street lamps, the same gas was burning, and it was long ago it was noted that with the accident in the gas pipeline, the trees standing next to the gas leakage, the trees are premature and dropped leaves.

Light gas contained a variety organic substances. To remove the accommodation of the gas, dislike passed it through a heated tube with copper oxide. In the "purified" air, the pea seedlings developed normally. In order to find out what kind of substance causes the answer of the seedlings, the dislikes added various components of the luminaire gas in turn, and found that ethylene additive causes:

1) slowdown growth in length and thickening of the seedlings,

2) "non-inflating" apical loop,

3) Changing the orientation of the seedlings in space.

This physiological reaction of seedlings was named triple response to ethylene. The peas turned out to be so sensitive to ethylene, which began to be used in biotestes to determine the low concentrations of this gas. Soon it was found that ethylene causes other effects: leaf fall, ripening fruits, etc. It turned out that ethylene is able to synthesize the plants themselves, i.e. Ethylene is a phytohormon (Petushkova, 1986).

Physical properties of ethylene

Ethylene - Organic chemical compounddescribed by formula C 2 H 4. Is the simplest alkene ( olefin).

Ethylene is a colorless gas with a weak sweet smell of a density of 1.178 kg / m³ (lighter air), its inhalation has a narcotic effect on man. Ethylene dissolves on ether and acetone, significantly less - in water and alcohol. When mixed with air forms an explosive mixture

Hardens at -169.5 ° C, melted under the same temperature conditions. Pipes ethen at -103.8 ° C. It is flammable when heated to 540 ° C. Gas burns well, flames luminous, with a weak soot. The rounded molar mass of the substance is 28 g / mol. The third and fourth representatives of the homologous series of etume are also gaseous substances. The physical properties of the fifth and the following alkenes are distinguished, they are liquids and solid bodies.

Obtaining ethylene

Main ways to produce ethylene:

Dehydrogalogeneration of halogen derivatives of alkanes under the action of alkalis alcohol solutions

CH 3 -CH 2 -BR + KOH → CH 2 \u003d CH 2 + KBR + H 2 O;

Degalogenation of dihagogen derivatives of alkanes under the action of active metals

CL-CH 2 -CH 2 -Cl + Zn → ZnCl 2 + CH 2 \u003d CH 2;

Dehydration of ethylene when heated with sulfuric acid (T\u003e 150˚ C) or passing its vapors over the catalyst

CH 3 -CH 2 -OH → CH 2 \u003d CH 2 + H 2 O;

Dehydrization of ethane when heated (500c) in the presence of a catalyst (Ni, Pt, Pd)

CH 3 -CH 3 → CH 2 \u003d CH 2 + H 2.

Chemical properties ethylene

For ethylene, the reaction occurs by the mechanism of electrophile, addition, the reaction of radical substitution, oxidation, recovery, polymerization.

1. Haloiding(Electrophile addition) - the interaction of ethylene with halogens, for example, with bromine, in which the discoloration of bromine water is discoloration:

CH 2 \u003d CH 2 + BR 2 \u003d BR-CH 2 -CH 2 Br.

Halolation of ethylene is also possible when heated (300 ° C), in this case, the dual bond break does not occur - the reaction proceeds through the radical substitution mechanism:

CH 2 \u003d CH 2 + CL 2 → CH 2 \u003d CH-CL + HCl.

2. Hydroleogenation - The interaction of ethylene with halogenesis (HCl, HBr) with the formation of halogen derivatives of alkanes:

CH 2 \u003d CH 2 + HCl → CH 3 -CH 2 -CL.

3. Hydration - The interaction of ethylene with water in the presence of mineral acids (sulfur, phosphate) to form a limit monohydric alcohol - ethanol:

CH 2 \u003d CH 2 + H 2 O → CH 3 -CH 2 -On.

Among the reactions of electrophile attachment allocate the connection chlornanotic acid(1) reaction hydroxy and alkoxymecution (2, 3) (getting mercury compounds) and hydroptication (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).

The reactions of nucleophilic connectivity are characteristic of ethylene derivatives containing electron-coceptor substituents. Among the nucleophilic addition reactions, the reaction of the addition of cyanoic acid, ammonia, ethanol is occupied by a special place. For example,

2 ON-CH \u003d CH 2 + HCN → 2 ON-CH 2 -CH 2 -CN.

4. Oxidation. Ethylene is easily oxidized. If ethylene passes through the potassium permanganate solution, then it will discourage. This reaction is used to differ marginal and unsaturated compounds. As a result, ethylene glycol is formed

3CH 2 \u003d CH 2 + 2KMNO 4 + 4H 2 O \u003d 3CH 2 (OH) -CH 2 (OH) + 2MNO 2 + 2KOH.

For hard oxidation Ethylene with a boiling solution of potassium permanganate in an acidic medium occurs a complete bond of communication (σ-bonds) to form 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. For recovery Ethylene is the formation of ethane, representative of alkanov. The reaction of the reduction (hydrogenation reaction) of ethylene proceeds along the radical mechanism. The condition of the reaction is the presence of catalysts (Ni, Pd, Pt), as well as heating the reaction mixture:

CH 2 \u003d CH 2 + H 2 \u003d CH 3 -CH 3.

6. Ethylene enters polymerization reaction. Polymerization is the process of forming a high molecular compound - polymer-by compounding with each other using the main valencies of the molecules of the initial low molecular weight substance - the monomer. The polymerization of ethylene occurs under the influence of acids (cationic mechanism) or radicals (radical mechanism):

n ch 2 \u003d CH 2 \u003d - (- CH 2 -CH 2 -) N -.

7. Burning:

C 2 H 4 + 3O 2 → 2CO 2 + 2H 2 O

8. Dimyrization. Dimyrization - The process of forming a new substance by connecting two structural elements (molecules, including proteins, or particles) in the 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 constructed, and as a starting material for other two-carbon compounds. Polymerization is repetitive combining of a plurality of small ethylene molecules in larger. This process occurs at high pressures and temperatures. The areas of ethylene use 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 concerns the formation of linear α-olefins. Ethylene is the source 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, ethylene properties make it biologically and economically significant.

The properties of ethylene give a good commercial basis for a large number of organic (containing carbon and hydrogen) materials. Single ethylene molecules can be connected together to produce polyethylene (which means many ethylene molecules). Polyethylene is used for the manufacture of plastics. In addition, it can be used for making detergents and synthetic lubricantsthat represent chemical substancesused to reduce friction. The use of ethylene to obtain styrers is relevant in the process of creating rubber and protective packaging. In addition, it is used in the shoe industry, especially for sports shoes, as well as in production automotive tires. The use of ethylene is commercially important, and gas itself is one of the most frequently produced hydrocarbons on a global scale.

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

Encyclopedic YouTube.

• 1 / 5

  Ethylene began to be widely used as a monomer before the Second World War due to the need to obtain high-quality insulating material capable of replacing polyvinyl chloride. After developing the method of polymerization of ethylene under high pressure and study dielectric properties The resulting polyethylene began its production first in the UK, 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 tubular furnaces at + 800-950 ° C and a pressure of 0.3 MPa. When using a straight-rich gasoline, ethylene yield is approximately 30% as raw materials. Simultaneously with ethylene, a significant amount of liquid hydrocarbons is also formed, including aromatic. With gas oil pyrolysis, ethylene yield is approximately 15-25%. The greatest yield of ethylene is up to 50% - is achieved when used as raw materials of saturated hydrocarbons: ethane, propane and butane. Their pyrolysis is carried out in the presence of water vapor.

  When issuing production, with commodity-accounting operations, when checking it on compliance with the regulatory and technical documentation, ethylene samples are selected according to the procedure described in GOST 24975.0-89 "Ethylene and propylene. Sampling methods. Selection of ethylene sample can be carried out in gaseous and liquefied into special samplers according to GOST 14921.

  The ethylene industrially obtained in Russia must comply with the requirements set out in GOST 25070-2013 "Ethylene. Technical conditions. "

  Production structure

  Currently, in the structure of production of ethylene, 64% falls on large-tonnage installations of pyrolysis, ~ 17% - on low-tonnage installations of gas pyrolysis, ~ 11% is pyrolysis of gasoline and 8% falls on the pyrolysis of ethane.

  Application

  Ethylene is the leading product of the main 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 in a mixture with oxygen was used in medicine for anesthesia until the mid-1980s in the USSR and the Middle East. Ethylene is a phythormon almost all plants, among other things, is responsible for the foaming of the needles at 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 a 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 in the perpendicular plane π-bond with a p-electron of a neighboring carbon atom. So the double bond between carbon atoms is formed. The molecule has a plane structure.

  CH 2 \u003d CH 2

  Basic chemical properties

  Ethylene is a chemically active substance. Since there is a double bond in the molecule between carbon atoms, then one of them, less durable, is easily broken, and at the place of breaking the connection, the oxidation, polymerization of molecules occurs.

  • Halogenation:
  CH 2 \u003d CH 2 + BR 2 → CH 2 BR-CH 2 BR is discoloration of bromine water. This is a high-quality response to unsaturated compounds.
  • Hydrogenation:
  CH 2 \u003d CH 2 + H - H → CH 3 - CH 3 (under the action of Ni)
  • Hydroalogenation:
  CH 2 \u003d CH 2 + HBR → CH 3 - CH 2 BR
  • Hydration:
  CH 2 \u003d CH 2 + HOH → CH 3 CH 2 OH (under the action of the catalyst) This reaction opened A.M. Butlers, and it is used for industrial production of ethyl alcohol.
  • Oxidation:
  Ethylene is easily oxidized. If ethylene passes through the potassium permanganate solution, then it will discourage. This reaction is used to differ marginal and unsaturated compounds. As a result, ethylene glycol is formed. Reaction equation: 3CH 2 \u003d CH 2 + 2KMNO 4 + 4H 2 O → 3HOH 2 C - CH 2 OH + 2MNO 2 + 2KOH
  • Combustion:
  C 2 H 4 + 3O 2 → 2CO 2 + 2H 2 O
  • Polymerization (polyethylene receipt):
  NCH \u200b\u200b2 \u003d CH 2 → (-CH 2 -CH 2 -) N
  • Dimyrization (V. Sh. Feldblum. Dimyrization and disproportionation of olefins. M.: Chemistry, 1978)
  2ch 2 \u003d CH 2 → CH 2 \u003d CH-CH 2 -CH 3

  Biological role

  Ethylene is the first of the detected gaseous vegetable hormones, which has a very wide range of biological effects. Ethylene performs B. life cycle Plants diverse functions, among which the control of the development of the seedlings, the ripening of fruits (in particular, fruits), dissolving buds (flowering process), aging and falling leaves and flowers. Ethylene is also called a stress hormone, as it is involved in the reaction of plants on biotic and abiotic stress, and its synthesis in plants in response to various damage. In addition, being a volatile gaseous substance, ethylene carries out rapid communication between different plants and between plants in the population, which is important. In particular, with the development of stress-stability.

  The most famous functions of ethylene include the development of the so-called triple response in the etholyted (grown in the dark) of seedlings when processing this hormone. The triple response includes three reactions: shortening and thickening hypocotyl, root shortening and enhancing the apical hook (sharp bending of the upper part of the hypocotyle). The response of the seedlings on ethylene is extremely important in the first stages of their development, as it contributes to the penetration of sprouts to light.

  In the commercial collection of fruits and fruits, special rooms or cameras for the ripening of fruits are used into the atmosphere of which ethylene is injected from special catalytic generators producing gas-made ethylene from liquid ethanol. Usually, the concentration of ethylene gaseous ethylene in the atmosphere of the chamber from 500 to 2000 ppm is used to stimulate the fruit of fruits within 24-48 hours. With a higher air temperature and a higher concentration of ethylene in the air, the fruit ripening is faster. It is important, however, while ensuring control of carbon dioxide in the atmosphere of the chamber, since high-temperature ripening (at temperatures above 20 degrees Celsius) or ripening at a high concentration of ethylene in the air of the chamber leads to a sharp increase in carbon dioxide allocation by fast ripening fruits, sometimes up to 10% Carbon dioxide in the air 24 hours from the beginning of the ripening, which can lead to carbon dioxide poisoning both workers who have already removed the fruits and the fruit themselves.

  Ethylene was used to stimulate the ripening of fruits even in Ancient Egypt. The ancient Egyptians deliberately scratched or slightly miles, chopped by dates, figs and other fruits in order to stimulate their ripening (tissue damage stimulates ethylene formation by plant tissues). The ancient Chinese burned wooden aromatic sticks or aromatic candles in closed rooms in order to stimulate the ripening of peaches (during the combustion of the candle or wood, not only carbon dioxide, but also unsophisticated intermediate combustion products, including ethylene). In 1864, it was found that the leakage of natural gas from street lamps causes the growth of the growth of nearby plants in length, their twisting, anomalous thickening of the stems and roots and the accelerated ripening of fruits. In 1901, the Russian scientist Dmitry Nelyubov showed that the active component of natural gas that causes these changes is not its main component, methane, and the ethylene present in small quantities. Later in 1917, Sarah Dubt proved that ethylene stimulates the premature fiction of the leaves. However, only in 1934, Hein found that the plants themselves synthesize endogenous ethylene. In 1935, the Crocker suggested that ethylene is a vegetable hormone responsible for the physiological regulation of the ripening of fruits, as well as for the aging of vegetative tissues of the plant, the fond of leaves and braking growth.

  The cycle of ethylene biosynthesis begins with the conversion of methionine amino acid into S-adenosyl-methionine (SAME) using the methionine-adenosyltransferase enzyme. Then, S-adenosyl methionine is converted to 1-aminocyclopropane-1-carboxylic acid (ACC, ACC.) Using the enzyme 1-aminocyclopropan-1-carboxylate synthetase (ACC synthetase). The ACC synthetase activity limits the speed of the entire cycle, so the 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 amino-cyclopropancarboxylate oxidase enzyme (ACC-oxidase), which was previously known as an ethylene-aging enzyme. Ethylene biosynthesis in plants is induced both exogenous and endogenous ethylene (positive feedback). ACC synthetase activity and, accordingly, ethylene formation also increases high levels Auxins, especially indoleutaceous acid, and cytokinins.

  The ethylene signal in plants is perceived by at least five different families of transmembrane receptors, which are protein dimers. Known, in particular, ethylene receptor ETR 1 in Arabidopsis ( Arabidopsis). Genes encoding receptors for ethylene were cloned with Arabidopsis and then at tomato. Ethylene receptors are encoded by a plurality of genes both in the agent of Arabidopsis and the genome of the tomatoes. Mutations in any of the gene family, which consists of five types of ethylene receptors in Arabidopsis and a minimum of six types of receptors at tomato, can lead to the insensitivity of plants to ethylene and violations of ripening, growth and wilting processes. DNA sequences characteristic of genes of ethylene receptors were also discovered in many other plant species. Moreover, ethylene binding protein was found even in cyanobacteria.

  Unfavorable external factors, such as insufficient oxygen content in the atmosphere, flooding, drought, frost, mechanical damage (wound) of plants, attack pathogenic microorganisms, fungi or insects, can cause an elevated ethylene formation in plant tissues. For example, when flooding the roots of the plant suffer from excess water and lack of oxygen (hypoxia), which leads to the biosynthesis of 1-aminocyclopropane-1-carboxylic acid. The ACC is then transported by conductive paths in the stems up, before the leaves, and in the leaves oxidized to ethylene. The resulting ethylene contributes to epinastic movements leading to mechanical shaking of water from the leaves, as well as fading and falling out of leaves, flowers of flowers and fruits, which allows the plant at the same time and get rid of excess water in the body, and reduce the need for oxygen by reducing the total mass of tissues.

  Small amounts of endogenous ethylene are also formed in animal cells, including a person, in the process of lipid peroxidation. A certain amount of endogenous ethylene is then oxidized to ethylene oxide, which has the ability to alkyl DNA and proteins, including hemoglobin (forming a specific adduct with N-terminal roline hemoglobin - N-hydroxyethyl-valine). Endogenous ethylene oxide can also alkyl the guanine bases of DNA, which leads to the formation of an adduct of 7- (2-hydroxyethyl) -guanine, and is one of the reasons inherent in all living beings of the risk of endogenous carcinogenesis. 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, respectively, ethylene oxide, then the rate of occurrence of spontaneous mutations and, accordingly, the speed of evolution would be significantly lower.

  Notes

  1. Devanney Michael T. Ethylne. (eng.). SRI CONSULTING (September 2009). Archived August 21, 2011.
  2. Ethylne. (eng.). WP Report. SRI CONSULTING (January 2010). Archived August 21, 2011.
  3. 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 main state sanitary doctor of the Russian Federation 30.03.2003)
  4. "Growth and development of plants" V. V. Chub
  5. "DeLaying Christmas Tree Needle Loss"
  6. Homchenko G.P. §16.6. Ethylene and his homolog // Chemistry for applicants to universities. - 2nd ed. - M.: Higher School, 1993. - P. 345. - 447 p. - ISBN 5-06-002965-4.
  7. 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.
  8. Ethylene and Fruit Ripening / J Plant Growth Regul (2007) 26: 143-159 DOI: 10.1007 / S00344-007-9002-Y (English)
  9. Lutova L.A. Genetics of plant development / Ed. S.G. Inge-eternal. - 2nd ed. - St. Petersburg: Nr, 2010. - P. 432.
  10. . ne-postharvest.com. (Inaccessible link from 06-06-2015)
  11. Nelyubov D. N. (1901). "On horizontal nation at Pisum Sativum and some other plants." Proceedings of St. Petersburg Society of Natural Science. 31 (one). Also Beihefte Zum "Bot. CentralBlatt », so x, 1901

  Obtaining

  Ethylene began to be widely used as a monomer before the Second World War due to the need to obtain high-quality insulating material capable of replacing polyvinyl chloride. After developing the method of polymerization of ethylene under high pressure and studying the dielectric properties of the obtained polyethylene, its production began first in the UK, 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 tubular furnaces at + 800-950 ° C and a pressure of 0.3 MPa. When using a straight-rich gasoline, ethylene yield is approximately 30% as raw materials. Simultaneously with ethylene, a significant amount of liquid hydrocarbons is also formed, including aromatic. With gas oil pyrolysis, ethylene yield is approximately 15-25%. The greatest yield of ethylene is up to 50% - is achieved when used as raw materials of saturated hydrocarbons: ethane, propane and butane. Their pyrolysis is carried out in the presence of water vapor.

  When issuing production, with commodity-accounting operations, when checking it on compliance with the regulatory and technical documentation, ethylene samples are selected according to the procedure described in GOST 24975.0-89 "Ethylene and propylene. Sampling methods. Selection of ethylene sample can be carried out in gaseous and liquefied into special samplers according to GOST 14921.

  The ethylene industrially obtained in Russia must comply with the requirements set out in GOST 25070-2013 "Ethylene. Technical conditions. "

  Production structure

  Currently, in the structure of production of ethylene, 64% falls on large-tonnage installations of pyrolysis, ~ 17% - on low-tonnage installations of gas pyrolysis, ~ 11% is pyrolysis of gasoline and 8% falls on the pyrolysis of ethane.

  Application

  Ethylene is the leading product of the main 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 in a mixture with oxygen was used in medicine for anesthesia until the mid-1980s in the USSR and the Middle East. Ethylene is a phythormon almost all plants, among other things, is responsible for the foaming of the needles at 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 a 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 in the perpendicular plane π-bond with a p-electron of a neighboring carbon atom. So the double bond between carbon atoms is formed. The molecule has a plane structure.

  Basic chemical properties

  Ethylene is a chemically active substance. Since there is a double bond in the molecule between carbon atoms, then one of them, less durable, is easily broken, and at the place of breaking the connection, the oxidation, polymerization of molecules occurs.

  • Halogenation:
  CH 2 \u003d CH 2 + B R 2 → CH 2 B R - CH 2 B R + D (\\ DisplayStyle (\\ Mathsf (CH_ (2) (\\ Text (\u003d)) CH_ (2) + BR_ (2) \\ RightArrow Ch_ (2) br (\\ text (-)) ch_ (2) br + d))) There is a discoloration of bromine water. This is a high-quality response to unsaturated compounds.
  • Hydrogenation:
  CH 2 \u003d CH 2 + H 2 → N I CH 3 - CH 3 (\\ DisplayStyle (\\ MathSF (CH_ (2) (\\ Text (\u003d)) CH_ (2) + H_ (2) (\\ xrightarrow [()] (Ni)) ch_ (3) (\\ Text (-)) ch_ (3))))
  • Hydroalogenation:
  CH 2 \u003d CH 2 + HB R → CH 3 CH 2 B R (\\ DisplayStyle (\\ Mathsf (CH_ (2) (\\ Text (\u003d)) CH_ (2) + HBB \\ RIGHTARROW CH_ (3) CH_ (2) BR )))
  • Hydration:
  CH 2 \u003d CH 2 + H 2 O → H + CH 3 CH 2 OH (\\ DisplayStyle (\\ MathSF (CH_ (2) (\\ Text (\u003d)) ch_ (2) + H_ (2) O (\\ xrightarrow [( )] (H ^ (+))) ch_ (3) ch_ (2) oh))) This reaction was opened by A.M. Butlers, and it is used for industrial production of ethyl alcohol.
  • Oxidation:
  Ethylene is easily oxidized. If ethylene passes through the potassium permanganate solution, then it will discourage. This reaction is used to differ marginal and unsaturated compounds. As a result, ethylene glycol is formed. Reaction equation: 3 CH 2 \u003d CH 2 + 2 KM N O 4 + 4 H 2 O → CH 2 OH - CH 2 OH + 2 M N O 2 + 2 KOH (\\ DisplayStyle (\\ MathSF (3CH_ (2) (\\ Text (\u003d )) Ch_ (2) + 2kmno_ (4) + 4h_ (2) o \\ rightarrow ch_ (2) oh (\\ Text (-)) ch_ (2) OH + 2MNO_ (2) + 2KOH)))
  • Combustion:
  CH 2 \u003d CH 2 + 3 O 2 → 2 CO 2 + 2 H 2 O (\\ DisplayStyle (\\ Mathsf (CH_ (2) (\\ Text (\u003d)) CH_ (2) + 3O_ (2) \\ RIGHTARROW 2CO_ (2 ) + 2H_ (2) O)))
  • Polymerization (polyethylene receipt):
  N CH 2 \u003d CH 2 → (- CH 2 - CH 2 -) N (\\ DisplayStyle (\\ MathSF (NCH_ (2) (\\ Text (\u003d)) ch_ (2) \\ Rightarrow ((\\ Text (-)) ch_ (2) (\\ Text (-)) ch_ (2) (\\ Text (-))) _ (n)))) 2 CH 2 \u003d CH 2 → CH 2 \u003d CH - CH 2 - CH 3 (\\ DisplayStyle (\\ MathsF (2ch_ (2) (\\ Text (\u003d)) ch_ (2) \\ Rightarrow ch_ (2) (\\ Text (\u003d )) Ch (\\ Text (-)) ch_ (2) (\\ text (-)) ch_ (3))))

  Biological role

  The most famous functions of ethylene include the development of the so-called triple response in the etholyted (grown in the dark) of seedlings when processing this hormone. The triple response includes three reactions: shortening and thickening hypocotyl, root shortening and enhancing the apical hook (sharp bending of the upper part of the hypocotyle). The response of the seedlings on ethylene is extremely important in the first stages of their development, as it contributes to the penetration of sprouts to light.

  In the commercial collection of fruits and fruits, special rooms or cameras for the ripening of fruits are used into the atmosphere of which ethylene is injected from special catalytic generators producing gas-made ethylene from liquid ethanol. Usually, the concentration of ethylene gaseous ethylene in the atmosphere of the chamber from 500 to 2000 ppm is used to stimulate the fruit of fruits within 24-48 hours. With a higher air temperature and a higher concentration of ethylene in the air, the fruit ripening is faster. It is important, however, while ensuring control of carbon dioxide in the atmosphere of the chamber, since high-temperature ripening (at temperatures above 20 degrees Celsius) or ripening at a high concentration of ethylene in the air of the chamber leads to a sharp increase in carbon dioxide allocation by fast ripening fruits, sometimes up to 10% Carbon dioxide in the air 24 hours from the beginning of the ripening, which can lead to carbon dioxide poisoning both workers who have already removed the fruits and the fruit themselves.

  Ethylene was used to stimulate the ripening of fruits in ancient Egypt. The ancient Egyptians deliberately scratched or slightly miles, chopped by dates, figs and other fruits in order to stimulate their ripening (tissue damage stimulates ethylene formation by plant tissues). The ancient Chinese burned wooden aromatic sticks or aromatic candles in closed rooms in order to stimulate the ripening of peaches (during the combustion of the candle or wood, not only carbon dioxide, but also unsophisticated intermediate combustion products, including ethylene). In 1864, it was found that the leakage of natural gas from street lamps causes the growth of the growth of nearby plants in length, their twisting, anomalous thickening of the stems and roots and the accelerated ripening of fruits. In 1901, the Russian scientist Dmitry Nelyubov showed that the active component of natural gas that causes these changes is not its main component, methane, and the ethylene present in small quantities. Later in 1917, Sarah Dubt proved that ethylene stimulates the premature fiction of the leaves. However, only in 1934, Hein found that the plants themselves synthesize endogenous ethylene. . In 1935, the Crocker suggested that ethylene is a vegetable hormone responsible for the physiological regulation of the ripening of fruits, as well as for the aging of vegetative tissues of the plant, the fond of leaves and braking growth.

  

  Cycle Yang.

  The cycle of ethylene biosynthesis begins with the conversion of methionine amino acid into S-adenosyl-methionine (SAME) using the methionine-adenosyltransferase enzyme. Then, S-adenosyl methionine is converted to 1-aminocyclopropane-1-carboxylic acid (ACC, ACC.) Using the enzyme 1-aminocyclopropan-1-carboxylate synthetase (ACC synthetase). The ACC synthetase activity limits the speed of the entire cycle, so the 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 amino-cyclopropancarboxylate oxidase enzyme (ACC-oxidase), which was previously known as an ethylene-aging enzyme. Ethylene biosynthesis in plants is induced both exogenous and endogenous ethylene (positive feedback). The activity of ACC synthetase and, accordingly, the formation of ethylene is also rising at high levels of auxins, especially indoletaceous acid, and cytokinins.

  The ethylene signal in plants is perceived by at least five different families of transmembrane receptors, which are protein dimers. Known, in particular, ethylene receptor ETR 1 in Arabidopsis ( Arabidopsis). Genes encoding receptors for ethylene were cloned with Arabidopsis and then at tomato. Ethylene receptors are encoded by a plurality of genes both in the agent of Arabidopsis and the genome of the tomatoes. Mutations in any of the gene family, which consists of five types of ethylene receptors in Arabidopsis and a minimum of six types of receptors at tomato, can lead to the insensitivity of plants to ethylene and violations of ripening, growth and wilting processes. DNA sequences characteristic of genes of ethylene receptors were also discovered in many other plant species. Moreover, ethylene binding protein was found even in cyanobacteria.

  Adverse external factors, such as insufficient oxygen content in the atmosphere, flooding, drought, frost, mechanical damage (injury) of plants, attack pathogenic microorganisms, fungi or insects, can cause an elevated formation of ethylene in plant tissues. For example, when flooding the roots of the plant suffer from excess water and lack of oxygen (hypoxia), which leads to the biosynthesis of 1-aminocyclopropane-1-carboxylic acid. The ACC is then transported by conductive paths in the stems up, before the leaves, and in the leaves oxidized to ethylene. The resulting ethylene contributes to epinastic movements leading to mechanical shaking of water from the leaves, as well as fading and falling out of leaves, flowers of flowers and fruits, which allows the plant at the same time and get rid of excess water in the body, and reduce the need for oxygen by reducing the total mass of tissues.

  Small amounts of endogenous ethylene are also formed in animal cells, including a person, in the process of lipid peroxidation. A certain amount of endogenous ethylene is then oxidized to ethylene oxide, which has the ability to alkyl DNA and proteins, including hemoglobin (forming a specific adduct with N-terminal roline hemoglobin - N-hydroxyethyl-valine). Endogenous ethylene oxide can also alkyl the guanine bases of DNA, which leads to the formation of an adduct of 7- (2-hydroxyethyl) -guanine, and is one of the reasons inherent in all living beings of the risk of endogenous carcinogenesis. 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, respectively, ethylene oxide, then the rate of occurrence of spontaneous mutations and, accordingly, the speed of evolution would be significantly lower.

  Notes

  1. Devanney Michael T. Ethylne. (eng.) (inaccessible link). SRI CONSULTING (September 2009). Archived on July 18, 2010.
  2. Ethylne. (eng.) (inaccessible link). WP Report. SRI CONSULTING (January 2010). Archived on August 31, 2010.
  3. 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 main state sanitary doctor of the Russian Federation 30.03.2003)
  4. "Growth and development of plants" V. V. Chub (Neopr.) (inaccessible link). Date of appeal January 21, 2007. Archived on January 20, 2007.
  5. "DeLaying Christmas Tree Needle Loss"
  6. Homchenko G.P. §16.6. Ethylene and his homolog // Chemistry for applicants to universities. - 2nd ed. - M.: Higher School, 1993. - P. 345. - 447 p. - ISBN 5-06-002965-4.
  7. V. Sh. Feldblum. Dimmerization and disproportionation of olefins. M.: Chemistry, 1978
  8. 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.
  9. Ethylene and Fruit Ripening / J Plant Growth Regul (2007) 26: 143-159 DOI: 10.1007 / S00344-007-9002-Y (English)
  10. Lutova L.A. Genetics of plant development / Ed. S.G. Inge-eternal. - 2nd ed. - St. Petersburg: Nr, 2010. - P. 432.
  11. . ne-postharvest.com Archival copy of September 14, 2010 on Wayback Machine
  12. Nelyubov D. N. (1901). "On horizontal nation at Pisum Sativum and some other plants." Proceedings of St. Petersburg Society of Natural Science. 31 (one). Also Beihefte Zum "Bot. CentralBlatt », so x, 1901