Ethylene

Etileno . It is a plant hormone that differs from other hormones in that it is a gas . Formula developed CH2 = CH2. Semi-developed formula. C2H4 condensed formula.

Summary

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• 1 Description
  • 1 Ethylene also controls many other functions of plants, such as:
• 2 Structure
• 3 Physical and chemical properties
  • 1 Physical properties
  • 2 Chemical properties
• 4 Obtaining
• 5 Sources

Description

It is a plant hormone that differs from other hormones in that it is a gas. As ripening approaches, many fruits (eg oranges , bananas , kivis , apples , avocados ) give off ethylene. This ethylene then promotes the ripening and senescence of the fruits.

Ethylene also controls many other functions of plants, such as:

• Abscission of leaves, fruits, flower petals.
• Leaf fall.
• Potato bulbs germination
• Seed germination
• Flower formation in some species

When the plant matures in its natural environment , ethylene is released into the surrounding air and naturally disappears. However, when a product is placed in a refrigerator , ethylene becomes trapped and begins to accumulate. This accumulation of ethylene accelerates maturation and causes the product to degenerate rapidly.

Small amounts of ethylene during storage and transportation cause most fruits and vegetables to spoil more quickly.

Structure

The molecule cannot rotate around the double bond and all the atoms are on the same plane. The angle between the two carbon – hydrogen bonds is 117 °, very close to 120 ° corresponding to an sp2 hybridization .

Physical and chemical properties

• Ethylene is the simplest unsaturated hydrocarbon
• It has a hybridizationtype SP²
• It is highly flammable
• It is polymerizableand peroxidable
• Reacts violently with oxidantsand chlorine in the presence of light.

Physical properties

• Aggregation status: GAS
• Appearance: COLORLESS
• Critical pressure: 50.7 atm
• Critical temperature: 282.9 K (10 ° C)
• Boiling point: 169.5 K (-104 ° C)
• Melting point: 104 K (-169 ° C)
• Molar mass: 28.05 g / mol
• Density: 1.1780 kg / m3 0.001178 g / cm3

Chemical properties

• Solubility: Miscible (in water)
• Acidity: 44 pKa
• Applications and products of ethylene: Ethylene occupies the most important segment of the petrochemicalindustry and is converted into a large number of final and intermediate products such as plastics , resins , fibers and elastomers (all of them polymers) and solvents, coatings, plasticizers and antifreeze. .
• Polyethylene (PE): It is a thermoplastic that is characterized by being resistant, flexible and not very dense. As application examples can be named containers, flexibletubes , ropes and films. There are two kinds of Polyethylene; the high-density one (0.941-0.970 grs / ml) that is used for pipes and drains, especially for large diameter corrugated shapes. And the low-density one (0.9100,940 grs / ml) that is used in the manufacture of films, cables, wires and paper coatings.
• Polyvinylchloride: Obtained by addition from ethylene chloride. Its main characteristics are being resistant, somewhat elastic and not very wearable; This is why it is used in floor, wall and tank linings, pipes and joints.
• Polystyrene (PS): It is obtained from styreneor phenylethene . It is characterized for being transparent and rigid so it can be used in injection, extrusion and thermoformed parts (discarded containers, refrigerator interiors) and also in insulation (expanded).
• Polyacrylonitrile: Acrylonitrile or cyanoethene is used as the monomer. It is a strong compound, easy to dye and can be spun. These characteristics make it suitable for the manufacture of textile fibers ( orlon, cashmilon , Dralon ).
• Polytetrafloruroethene (Teflon, Fluon): It is made from tetrafluoroethene. It is a very inert, non-adhesive and self-lubricating polymer, in addition to its great resistance to high temperatures. Examples of its application can be named gaskets, bushings, and coatings of kitchen utensils.
• Ethylene oxide: It is a colorless gas or a colorless, movable and flammable liquid. It is widely used as a chemical intermediate in the manufacture of ethylene glycol, polyethyleneglycols and their derivatives, ethanolamines , ethylene cyanhydrine, and nonionic detergents. It is also used as a fumigant. Of its derivatives, propylene oxide is the most important of the alkylene oxides, and styrene oxide is the most important of the aromatic derivatives.

Obtaining

Most of the ethylene produced worldwide is obtained by the steam cracking of refinery hydrocarbons ( ethane , propane , naphtha and diesel , mainly). Ethylene is also obtained from the catalytic reforming of naphtha or from natural gas (Oxidative Coupling of Methane, OCM). It can also be obtained in Organic Chemistry laboratories through the oxidation of Alcohols