User:Physchim62/Ethylene
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[edit] Molecular Geometry
Between the two carbon atoms a double bond exists. For a rotation around this connection a substantially larger energy expenditure is necessary than for the rotation around a carbon single bond. Due to sp² hybridizing the carbon atoms the molecule is planar, i.e. all atoms lie in one level. The angle between the two carbon-hydrogen bonds amounts to 117° and deviates thereby only easily from the theoretical value trigonal of the planar form with 120°.
Ethen is due to the high electron density between the two carbon atoms substantially more reactively than for example the Ethan.
[edit] Properties and Hazards
Due to the reactive C=C double bond the addition is to this connection a typical reaction of the Ethens. In water however well soluble Ethen are soluble with 0 °C only 250 ml/l Ethen, in organic (nonpolar) solvents are. Ethen has an easily suesslichen, unpleasant smell. The double bond of the alkenes can smell humans, the smell threshold lies with 260 ml/m³. The heat value of Ethen amounts to 59,955 kJ/Nm³. Ethen burns at air also easily Russian that, bright flame.
Ethen is high inflammatory. Ethenbehaelter must be kept at a well ventilated place. It is to be kept away from ignition sources, and measures must be met against electrostatic loading. Between an air volume portion from 3 to 36 per cent it forms explosive mixtures. In high concentration Ethen works as Betaeubungsmittel (see use). The flash point is with -136 °C, the zuendpunkt with 450 °C.
[edit] Herstellung/Vorkommen
Germany (2.9 million tons of 1989) is followed in Europe the largest Ethenhersteller, of France (2.5 million tons) and England (1.9 million tons). Originally Ethen was won by Dehydratisierung of ethanol or by isolation from coking plant gas, these procedures are still used despite disadvantages in relation to other procedures in many developing countries of South America, Asia and Africa. Nowadays it is won Ethan, or higher hydrocarbons, in the industrialized countries by Cracken by natural gas, oil, also it can be isolated from gas parliamentary groups, which result with erdoeldestillation. The yield with these procedures is substantially higher. In the laboratory it is won by elimination by 1,2 - Dichlorethan and zinc. With many petrochemical processes Ethen in large quantities results, it is therefore billig.In some erdgasvorkommen, usually in America, is to Ethengehalte of up to 20 per cent.
[edit] Ethene pipeline
In Germany and parts of the Netherlands a Ethen Pipelinesystem continues to exist to transport between the individual chemistry locations from Rotterdam over Antwerp into the area Cologne and into the Emscher lip area, as well as into the Rhine/Main area and to Ludwigshafen. The federal state governments of Lower Saxony and Schleswig-Holstein supported the Ethen pipeline of the Ruhr district to the German coast.
At the same time is those north and south the Elbe of convenient industrial sites Brunsbuettel and Stade with 54 kilometers is enough for chemistry and gas-Pipeline to be connected. Schleswig-Holstein and Lower Saxony want to improve the supply of raw materials of the chemistry enterprises at the coast and thus the sales prospects for their products in German and Europe with the pipeline. The planned connection is at the same time an element in the Chem Coast project of the federation of the chemical industry (VCI). In Stade connection exists to a Ethen pipeline after Boehlen in Saxonia. Beyond that a further connection is intended by Stade over Wilhelmshaven after gel churches, where large in each case chemical factories exist.
In Bavaria momentarily a pipeline between the chemistry triangle in the south and the chemistry location exists with Ingolstadt (ethyl pipeline Muenchsmuenster Gendorf). It is planned to extend to end of 2007 this piping to Ludwigshafen in order to manufacture the connection to the Northwestern European Ethen group.
[edit] Verwendung
Ethen is basic material for the production of numerous organic compounds such as Anthracen, 2-Chlorethanol, Chlorethan, Propanal, Ethanal, Isopren, vinyl acetate, propane acid, buten, styrene, Ethandiol and weitereren materials. Small quantities of Ethen are used for the production of materials such as ethylenoxid and ethanol. In the Wacker procedure Ethen is converted industrially using of molecular oxygen into aldehydes (acetaldehyde). Enormous quantities of aldehydes are produced annually according to this method.
Ethen was as Betaeubungsmittel beside laughing gas until a few years ago particularly with weak Betaeubungen used. It works narkotisch and muscle-relaxing. 1923 were used it in Chicago for the first time publicly, the narkotische effect of the Ethens are somewhat stronger than those of the laughing gas and have a similar effect mechanism. Today it is not however any longer used, since it is inflammable and smells unpleasantly. In addition the Narkosewirkung of the Ethens is not very good compared with other common Betaeubungsmitteln, around a good effect to obtain would have the Narkosegemisch at least 80 per cent of Ethen to contain.
Also to the tire of unreifer fruits like the pineapple, bananas and tomatoes it is used (see biological effect). Ethen is the moreover one a gaseous fuel and for high-speed flame spraying is used. Ethen is in the chemical industry output material for the synthesis of over 30 per cent of all Petrochemikalien, it the Ethin after the Second World War as far as possible displaced, because Ethin is to be manufactured more expensively, while Ethen results with industriellen processes in masses, since then oil in large masses is available.
It becomes besides the production of many plastics like the polyethylene, polyvinylether, polyvinyl chloride, polyester, which copolymer needs ethyl vinyl acetate or Polyvenylacetat and polystyrene (over ethylbenzol). In addition it is used for the production of pesticides and chemical weapons like the mustard gas (2,2-Dichlordiethylsulfid). In the post-war period became the Ethen, which develops with the burn of wood under luftabschluss (wood gas) because of lack of fuel also to the drive of truck used.
During the Second World War Ethengas was experimentally used by the special troop taifun with the attack on fortresses.
[edit] Biological properties
[edit] Plant hormone
Ethen is a Phytohormon (plant hormone). It is synthesized by plants on the basis of the amino acid Methionin, stimulated partly by the Phytohormon auxin. As hormone it affects germ growth and the aging of the plant. It causes the fruit maturing, the development of the blooms, the release of the sheets in the autumn as well as a dying of plant parts. As gaseous material one finds Ethen thereby before all in the areas between the cells, to the Interzellularen.
Already 1901 showed Dimitri Neljubow that Ethen releases the Tripleresponse in such a way specified with plants. This arises with germinating roots, which are begast with Ethen. Had been noticeable the effect with plants at defective town gas lines, which showed an unusual growth. Thereby a deactivation of the Gravitropismus acts, thus growth toward the terrestrial attraction force around an inhibition of length growth in cooperating with a verdickung of the stack and. This effect comes off by a reorientation of the Microtubuli, which give the growth direction (accumulation of cellulose fibers) of the germ as skeleton structures. They are brought by a vertical into a horizontal Orientation. As biological sense the overcoming is accepted of obstacles: Ethen is formed during entire growth and accumulates before obstacles, at these comes it to thickness growth and thus to a larger force development by the root point.
The second function of the Ethen refers to different aging processes of the plant. In addition both maturing of fruits and the development belong of blooms and the release of sheets (Abszission) or dying plant parts (Seneszenz). For these functions the avalanche-like increase of the available Ethenmenge, which come by the fact, is important that the synthesis is activated by Ethen by the operational readiness level of the same. In this way for instance a fruit in all places matures at the same time. The effect with maturing of fruits is used in the agriculture, in order to later arrange unreif harvested fruits to metabolic procedures, which let the fruits mature.
Since center of the 1990er years by purposeful gene change tomatoes are manufactured, which are particularly durable (Flavour Saver tomatoes). The gene responsible for the production of the Ethens thereby one switches off. These tomatoes can be begast then as required with Ethen and made ripe thus. Frequently fruits are intended not brought to the tire, then transport, and only at the destination by Ethen matured. Also unreife tomatoes can be made ripe, by to it-putting some ripe tomatoes. These separate Ethen and bring the unreifen tomatoes in such a way to the tire.
Ethen is likewise essential as "alarm material" with schaedlingsbefall at the plant as well as with verwundungen. Together with other materials like the Salicylsaeure and Jasmonat the Ethen causes a demarcation of the range concerned as well as the supply of vegetable poisons. As gas Ethen affects thereby also neighbouring plant parts or plants and sets the alarm cascade also there in motion.
The effect mechanism of the Ethen is investigated very little as with other Phytohormonen for still. One assumes that Ethen affects specific receptor molecules (Ethenrezeptor ETR) at the cell membranes, which start an effect cascade within the cell. It concerns concretely thereby the activation of the Serotonin Threonin Kinase CTR1. The signal passed on to different cell core proteins (EIN3/EIL-Proteine), which work as Transkriptionsfaktoren with the Genexpression and thus activate certain genes. First admitted goal gene of these proteins as Ethen Response factor 1 (ERF1) was described. This factor steers again several genes, so that with the effect of Ethen on this system a whole set of genetic activities are always released. During the fruit maturing different enzymes must be formed for the softening of the cell wall, with the Seneszenz chitin and cellulose-diminishing enzymes (Chitinasen, Zellulasen). Very extensively the repertoire is with the plant stress, thus the reaction to parasits and verwundungen, released by Ethen. Are produced in this situation under other Chitinasen (than poison materials for insects), Glucanasen, Proteinase inhibitors (restrictors for protein-diminishing enzymes, against mushrooms) and very many further defense materials.
The Ethen synthesis in the plant proceeds from the amino acid Methionin. The s-Adenosylmethionin in a first step from the coupling at adenosine (SAM) results. From the decay product 1-Aminocyclopropancarbonsaeure (ACC) by the ACC aCC-Oxidase Ethen is set free. The formation of the oxidase is stimulated by Ethen themselves (see above), whereby as with a nuclear chain reaction in neighbouring cells the Ethenbildung will priority-float.
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