Ethylene

Ethylene

Overview
Ethylene is a gaseous organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 with the formula . It is the simplest alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

 (older name: olefin from its oil-forming property). Because it contains a carbon-carbon double bond
Double bond
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...

, ethylene is classified as an unsaturated hydrocarbon
Unsaturated hydrocarbon
Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms. Those with at least one double bond are called alkenes and those with at least one triple bond are called alkynes...

. Ethylene is widely used in industry and is also a plant hormone
Plant hormone
Plant hormones are chemicals that regulate plant growth, which, in the UK, are termed 'plant growth substances'. Plant hormones are signal molecules produced within the plant, and occur in extremely low concentrations. Hormones regulate cellular processes in targeted cells locally and, when moved...

. Ethylene is the most produced organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 in the world; global production of ethylene exceeded 107 million tonnes in 2005. To meet the ever increasing demand for ethylene, sharp increases in production facilities are added globally, particularly in the Persian Gulf
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...

 countries and in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

.


This hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

 has four hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s bound to a pair of carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 atoms that are connected by a double bond
Double bond
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...

.
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Encyclopedia
Ethylene is a gaseous organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 with the formula . It is the simplest alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

 (older name: olefin from its oil-forming property). Because it contains a carbon-carbon double bond
Double bond
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...

, ethylene is classified as an unsaturated hydrocarbon
Unsaturated hydrocarbon
Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms. Those with at least one double bond are called alkenes and those with at least one triple bond are called alkynes...

. Ethylene is widely used in industry and is also a plant hormone
Plant hormone
Plant hormones are chemicals that regulate plant growth, which, in the UK, are termed 'plant growth substances'. Plant hormones are signal molecules produced within the plant, and occur in extremely low concentrations. Hormones regulate cellular processes in targeted cells locally and, when moved...

. Ethylene is the most produced organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 in the world; global production of ethylene exceeded 107 million tonnes in 2005. To meet the ever increasing demand for ethylene, sharp increases in production facilities are added globally, particularly in the Persian Gulf
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...

 countries and in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

.

Structure and properties



This hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

 has four hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s bound to a pair of carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 atoms that are connected by a double bond
Double bond
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...

. All six atoms that comprise ethylene are coplanar. The H-C-H angle
Angle
In geometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle.Angles are usually presumed to be in a Euclidean plane with the circle taken for standard with regard to direction. In fact, an angle is frequently viewed as a measure of an circular arc...

 is 119°, close to the 120° for ideal sp² hybridized carbon. The molecule is also relatively rigid: rotation about the C-C bond is a high energy process that requires breaking the π-bond.

The π-bond in the ethylene molecule is responsible for its useful reactivity. The double bond is a region of high electron density
Electron density
Electron density is the measure of the probability of an electron being present at a specific location.In molecules, regions of electron density are usually found around the atom, and its bonds...

, thus it is susceptible to attack by electrophiles. Many reactions of ethylene are catalyzed by transition metals, which bind transiently to the ethylene using both the π and π* orbitals.

Being a simple molecule, ethylene is spectroscopically simple. Its UV-vis spectrum
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...

 is still used as a test of theoretical methods.

Uses


Major industrial reactions of ethylene include in order of scale: 1) polymerization
Polymerization
In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...

, 2) oxidation, 3) halogenation
Halogenation
Halogenation is a chemical reaction that incorporates a halogen atom into a molecule in substitution of hydrogen atom. Halogenation takes place in the gas phase. There are four types of halogenation: fluorination, chlorination, bromination, and iodination...

 and hydrohalogenation
Hydrohalogenation
A hydrohalogenation reaction is the electrophilic addition of hydrohalic acids like hydrogen chloride or hydrogen bromide to alkenes to yield the corresponding haloalkanes....

, 4) alkylation
Alkylation
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbene . Alkylating agents are widely used in chemistry because the alkyl group is probably the most common group encountered in...

, 5) hydration
Hydration reaction
In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl group and a hydrogen cation are added to the two carbon atoms bonded together in the carbon-carbon double bond which makes up an alkene functional group. The reaction usually runs in a strong acidic, aqueous...

, 6) oligomerization, and 7) hydroformylation
Hydroformylation
Hydroformylation, also known as oxo synthesis or oxo process, is an important industrial process for the production of aldehydes from alkenes. This chemical reaction entails the addition of a formyl group and a hydrogen atom to a carbon-carbon double bond...

. In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, approximately 90% of ethylene is used to produce three chemical compounds—ethylene oxide
Ethylene oxide
Ethylene oxide, also called oxirane, is the organic compound with the formula . It is a cyclic ether. This means that it is composed of two alkyl groups attached to an oxygen atom in a cyclic shape . This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered...

, ethylene dichloride, and ethylbenzene
Ethylbenzene
Ethylbenzene is an organic compound with the formula C6H5CH2CH3. This aromatic hydrocarbon is important in the petrochemical industry as an intermediate in the production of styrene, which in turn is used for making polystyrene, a common plastic material....

—and a variety of kinds of polyethylene
Polyethylene
Polyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...

.



Polymerization



Polyethylenes of various types consume more than half of world ethylene supply. Polyethylene, also called polythene, is the world's most widely-used plastic, being primarily used to make films used in packaging, carrier bags and trash liners
Liners
"Liners" is a horticultural term referring to trays of very young plants, usually grown for sale to retailers or wholesalers, who then grow them to a larger size before selling them to consumers. Liners are usually grown from seed, but may also be grown from cuttings or tissue culture...

. Linear alpha-olefins, produced by oligomerization (formation of short polymers) are used as precursors
Precursor (chemistry)
In chemistry, a precursor is a compound that participates in the chemical reaction that produces another compound. In biochemistry, the term "precursor" is used more specifically to refer to a chemical compound preceding another in a metabolic pathway....

, detergents, plasticisers, synthetic lubricants, additives, and also as co-monomers in the production of polyethylenes.

Oxidation


Ethylene is oxidized to produce ethylene oxide
Ethylene oxide
Ethylene oxide, also called oxirane, is the organic compound with the formula . It is a cyclic ether. This means that it is composed of two alkyl groups attached to an oxygen atom in a cyclic shape . This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered...

, a key raw material in the production of surfactant
Surfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...

s and detergent
Detergent
A detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...

s by ethoxylation
Ethoxylation
Ethoxylation is an industrial process in which ethylene oxide is added to alcohols and phenols to give surfactants. The invention of the process is attributed to Schöller and Wittwer at I.G. Farben industrie.-Production:...

. Ethylene oxide also hydrolyzed to produce ethylene glycol
Ethylene glycol
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...

, widely used as an automotive antifreeze as well as higher molecular weight glycols and glycol ethers
Glycol Ethers
Glycol ethers are a group of solvents based on alkyl ethers of ethylene glycol commonly used in paints. These solvents typically have higher boiling point, together with the favorable solvent properties of lower molecular weight of ethers and alcohols. The word "Cellosolve" was registered in 1924...

.
Ethylene undergoes oxidation by palladium to give acetaldehyde
Acetaldehyde
Acetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants as part...

. This conversion remains a major industrial process (10M kg/y). The process proceeds via the initial complexation of ethylene to a Pd(II) center.

Halogenation and hydrohalogenation


Major intermediates from the halogenation
Halogenation
Halogenation is a chemical reaction that incorporates a halogen atom into a molecule in substitution of hydrogen atom. Halogenation takes place in the gas phase. There are four types of halogenation: fluorination, chlorination, bromination, and iodination...

 and hydrohalogenation
Hydrohalogenation
A hydrohalogenation reaction is the electrophilic addition of hydrohalic acids like hydrogen chloride or hydrogen bromide to alkenes to yield the corresponding haloalkanes....

 of ethylene include ethylene dichloride, ethyl chloride and ethylene dibromide. The addition of chlorine entails "oxychlorination," i.e. chlorine itself is not used. Some products derived from this group are polyvinyl chloride
Polyvinyl chloride
Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...

, trichloroethylene
Trichloroethylene
The chemical compound trichloroethylene is a chlorinated hydrocarbon commonly used as an industrial solvent. It is a clear non-flammable liquid with a sweet smell. It should not be confused with the similar 1,1,1-trichloroethane, which is commonly known as chlorothene.The IUPAC name is...

, perchloroethylene, methyl chloroform, polyvinylidiene chloride and copolymers, and ethyl bromide.

Alkylation


Major chemical intermediates from the alkylation
Alkylation
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbene . Alkylating agents are widely used in chemistry because the alkyl group is probably the most common group encountered in...

 with ethylene is ethylbenzene
Ethylbenzene
Ethylbenzene is an organic compound with the formula C6H5CH2CH3. This aromatic hydrocarbon is important in the petrochemical industry as an intermediate in the production of styrene, which in turn is used for making polystyrene, a common plastic material....

, precursor to styrene. Styrene is used principally in polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...

 for packaging and insulation, as well as in styrene-butadiene
Styrene-butadiene
Styrene-Butadiene or Styrene-Butadiene-Rubber is a synthetic rubber copolymer consisting of styrene and butadiene. It has good abrasion resistance and good aging stability when protected by additives, and is widely used in car tires, where it may be blended with natural rubber...

 rubber for tires and footwear. On a smaller scale, ethyltoluene
Toluene
Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinners. It is a mono-substituted benzene derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3.It is an aromatic...

, ethylanilines, 1,4-hexadiene, and aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 alkyls. Products of these intermediates include polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...

, unsaturated polyesters and ethylene-propylene terpolymers.

Oxo reaction


The hydroformylation
Hydroformylation
Hydroformylation, also known as oxo synthesis or oxo process, is an important industrial process for the production of aldehydes from alkenes. This chemical reaction entails the addition of a formyl group and a hydrogen atom to a carbon-carbon double bond...

 (oxo reaction) of ethylene results in propionaldehyde
Propionaldehyde
Propionaldehyde or propanal is the organic compound with the formula CH3CH2CHO. It is a saturated 3-carbon aldehyde and is a structural isomer of acetone...

, a precursor to propionic acid
Propionic acid
Propanoic acid is a naturally occurring carboxylic acid with chemical formula CH3CH2COOH. It is a clear liquid with a pungent odor...

 and n-propyl alcohol.

Hydration


Ethylene can be hydrated to give ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

, but this method is rarely used industrially.

Niche uses


An example of a niche use is as an anesthetic agent (in an 85% ethylene/15% oxygen ratio). It can also be used to hasten fruit ripening, as well as a welding gas.

Production


In 2006, global ethylene production was 109 million tonnes. By 2010 ethylene was produced by at least 117 companies in 55 countries.

Ethylene is produced in the petrochemical
Petrochemical
Petrochemicals are chemical products derived from petroleum. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as corn or sugar cane....

 industry by steam cracking. In this process, gaseous or light liquid hydrocarbons are heated to 750–950 °C, inducing numerous free radical reactions
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

 followed by immediate quench
Quench
In materials science, quenching is the rapid cooling of a workpiece to obtain certain material properties. It prevents low-temperature processes, such as phase transformations, from occurring by only providing a narrow window of time in which the reaction is both thermodynamically favorable and...

 to stop these reactions. This process converts large hydrocarbons into smaller ones and introduces unsaturation. Ethylene is separated from the resulting complex mixture by repeated compression and distillation
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

. In a related process used in oil refineries, high molecular weight hydrocarbons are cracked over zeolite
Zeolite
Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. The term zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that upon rapidly heating the material stilbite, it produced large amounts of steam from water that...

 catalysts. Heavier feedstocks, such as naphtha
Naphtha
Naphtha normally refers to a number of different flammable liquid mixtures of hydrocarbons, i.e., a component of natural gas condensate or a distillation product from petroleum, coal tar or peat boiling in a certain range and containing certain hydrocarbons. It is a broad term covering among the...

 and gas oils require at least two "quench towers" downstream of the cracking furnaces to recirculate pyrolysis-derived gasoline and process water. When cracking a mixture of ethane and propane, only one water quench tower is required.

The areas of an ethylene plant are:
  1. steam cracking furnaces:
  2. primary and secondary heat recovery with quench;
  3. a dilution steam recycle system between the furnaces and the quench system;
  4. primary compression of the cracked gas (3 stages of compression);
  5. hydrogen sulfide and carbon dioxide removal (acid gas removal);
  6. secondary compression (1 or 2 stages);
  7. drying of the cracked gas;
  8. cryogenic treatment;
  9. all of the cold cracked gas stream goes to the demethanizer tower. The overhead stream from the demethanizer tower consists of all the hydrogen and methane that was in the cracked gas stream. Cryogenically (-250 °F) treating this overhead stream separates hydrogen from methane. Methane recovery is critical to the economical operation of an ethylene plant.
  10. the bottom stream from the demethanizer tower goes to the deethanizer tower. The overhead stream from the deethanizer tower consists of all the ,'s that were in the cracked gas stream. The stream contains acetylene, which is explosive above 200 kPa (29 psi). If the partial pressure of acetylene is expected to exceed these values, the stream is partially hydrogenated. The 's then proceed to a splitter. The product ethylene is taken from the overhead of the tower and the ethane coming from the bottom of the splitter is recycled to the furnaces to be cracked again;
  11. the bottom stream from the de-ethanizer tower goes to the depropanizer tower. The overhead stream from the depropanizer tower consists of all the 's that were in the cracked gas stream. Before feeding the 's to the splitter, the stream is hydrogenated to convert the methylacetylene
    Methylacetylene
    Methylacetylene is an alkyne with the chemical formula H3C≡CH. It is a component of MAPP gas along with its isomer 1,2-propadiene , which is commonly used in gas welding...

     and propadiene
    Propadiene
    Propadiene is the organic compound with the formula H2C=C=CH2. It is the simplest allene, a compound with conjoined C=C double bonds. Propadiene's common name is allene...

     (allene
    Allene
    An allene is a compound in which one carbon atom has double bonds with each of its two adjacent carbon centres. Allenes are classified as polyenes with cumulated dienes. The parent compound of allene is propadiene. Compounds with an allene-type structure but with more than three carbon atoms are...

    ) mix. This stream is then sent to the splitter. The overhead stream from the splitter is product propylene and the bottom stream is propane which is sent back to the furnaces for cracking or used as fuel.
  12. The bottom stream from the depropanizer tower is fed to the debutanizer tower. The overhead stream from the debutanizer is all of the 's that were in the cracked gas stream. The bottom stream from the debutanizer (light pyrolysis gasoline) consists of everything in the cracked gas stream that is or heavier.


Since ethylene production is energy intensive, much effort has been dedicated to recovering heat from the gas leaving the furnaces. Most of the energy recovered from the cracked gas is used to make high pressure (1200 psig) steam. This steam is in turn used to drive the turbines for compressing cracked gas, the propylene refrigeration compressor, and the ethylene refrigeration compressor. An ethylene plant, once running, does not need to import steam to drive its steam turbines. A typical world scale ethylene plant (about 1.5 billion pounds of ethylene per year) uses a 45000 hp cracked gas compressor, a 30000 hp propylene compressor, and a 15000 hp ethylene compressor.

Laboratory synthesis


Ethylene can be produced via ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 dehydration by heating absolute ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 with concentrated sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 or by passing ethanol vapor over hot aluminum oxide catalyst.

Interestingly for such a useful compound, ethylene is rarely used in organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

 in the laboratory.

Ethylene as a plant hormone


Ethylene serves as a hormone
Plant hormone
Plant hormones are chemicals that regulate plant growth, which, in the UK, are termed 'plant growth substances'. Plant hormones are signal molecules produced within the plant, and occur in extremely low concentrations. Hormones regulate cellular processes in targeted cells locally and, when moved...

 in plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s. It acts at trace levels throughout the life of the plant by stimulating or regulating the ripening
Ripening
Ripening is a process in fruits that causes them to become more palatable. In general, a fruit becomes sweeter, less green, and softer as it ripens. Even though the acidity of fruit increases as it ripens, the higher acidity level does not make the fruit seem tarter, which can lead to the...

 of fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

, the opening of flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s, and the abscission
Abscission
Abscission is a term used in several areas of biology. In plant sciences it most commonly refers to the process by which a plant drops one or more of its parts, such as a leaf, fruit, flower or seed...

 (or shedding) of leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...

.
Commercial ripening rooms use "catalytic generators" to make ethylene gas from a liquid supply of ethanol. Typically, a gassing level of 500 ppm to 2,000 ppm is used, for 24 to 48 hours. Care must be taken to control carbon dioxide levels in ripening rooms when gassing, as high temperature ripening (68F) has been seen to produce CO2 levels of 10% in 24 hours.

History of ethylene in plant biology


Ethylene has been used in practice since the ancient Egyptians, who would gash figs in order to stimulate ripening (wounding stimulates ethylene production by plant tissues). The ancient Chinese would burn incense
Incense
Incense is composed of aromatic biotic materials, which release fragrant smoke when burned. The term "incense" refers to the substance itself, rather than to the odor that it produces. It is used in religious ceremonies, ritual purification, aromatherapy, meditation, for creating a mood, and for...

 in closed rooms to enhance the ripening of pears. In 1864, it was discovered that gas leaks from street lights led to stunting of growth, twisting of plants, and abnormal thickening of stems. In 1901, a Russian scientist named Dimitry Neljubow showed that the active component was ethylene. Doubt discovered that ethylene stimulated abscission
Abscission
Abscission is a term used in several areas of biology. In plant sciences it most commonly refers to the process by which a plant drops one or more of its parts, such as a leaf, fruit, flower or seed...

 in 1917. It wasn't until 1934 that Gane reported that plants synthesize ethylene. In 1935, Crocker proposed that ethylene was the plant hormone responsible for fruit ripening as well as senescence
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...

 of vegetative tissues.

Ethylene biosynthesis in plants


Ethylene is produced from essentially all parts of higher plants, including leaves, stems, roots, flowers, fruits, tubers, and seedlings.
"Ethylene production is regulated by a variety of developmental and environmental factors. During the life of the plant, ethylene production is induced during certain stages of growth such as germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

, ripening
Ripening
Ripening is a process in fruits that causes them to become more palatable. In general, a fruit becomes sweeter, less green, and softer as it ripens. Even though the acidity of fruit increases as it ripens, the higher acidity level does not make the fruit seem tarter, which can lead to the...

 of fruits, abscission
Abscission
Abscission is a term used in several areas of biology. In plant sciences it most commonly refers to the process by which a plant drops one or more of its parts, such as a leaf, fruit, flower or seed...

 of leaves, and senescence
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...

 of flowers. Ethylene production can also be induced by a variety of external aspects such as mechanical wounding, environmental stresses, and certain chemicals including auxin and other regulators".


The biosynthesis
Biosynthesis
Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...

 of the hormone starts with conversion of the amino acid methionine
Methionine
Methionine is an α-amino acid with the chemical formula HO2CCHCH2CH2SCH3. This essential amino acid is classified as nonpolar. This amino-acid is coded by the codon AUG, also known as the initiation codon, since it indicates mRNA's coding region where translation into protein...

 to S-adenosyl-L-methionine
S-Adenosyl methionine
S-Adenosyl methionine is a common cosubstrate involved in methyl group transfers. SAM was first discovered in Italy by G. L. Cantoni in 1952. It is made from adenosine triphosphate and methionine by methionine adenosyltransferase . Transmethylation, transsulfuration, and aminopropylation are the...

 (SAM, also called Adomet) by the enzyme Met Adenosyltransferase. SAM is then converted to 1-aminocyclopropane-1-carboxylic-acid (ACC) by the enzyme ACC synthase (ACS)
1-aminocyclopropane-1-carboxylate synthase
In enzymology, a 1-aminocyclopropane-1-carboxylate synthase is an enzyme that catalyzes the chemical reactionHence, this enzyme has one substrate, S-adenosyl-L-methionine, and two products, 1-aminocyclopropane-1-carboxylate and methylthioadenosine....

; the activity of ACS determines the rate of ethylene production, therefore regulation of this enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 is key for the ethylene biosynthesis. The final step requires oxygen and involves the action of the enzyme ACC-oxidase
Aminocyclopropanecarboxylate oxidase
In enzymology, an aminocyclopropanecarboxylate oxidase is an enzyme that catalyzes the chemical reactionThe 3 substrates of this enzyme are 1-aminocyclopropane-1-carboxylate, ascorbate, and O2, whereas its 5 products are ethylene, cyanide, dehydroascorbate, CO2, and H2O.This enzyme belongs to the...

 (ACO), formerly known as the Ethylene Forming Enzyme (EFE). Ethylene biosynthesis can be induced by endogenous or exogenous ethylene. ACC synthesis increases with high levels of auxin
Auxin
Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by...

s, especially Indole
Indole
Indole is an aromatic heterocyclic organic compound. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. Indole is a popular component of fragrances and the precursor to many pharmaceuticals. Compounds that contain an...

 acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...

 (IAA), and cytokinin
Cytokinin
Cytokinins are a class of plant growth substances that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence...

s. ACC synthase
Synthase
In biochemistry, a synthase is an enzyme that catalyses a synthesis process.Following the EC number classification, they belong to the group of ligases, with lyases catalysing the reverse reaction....

 is inhibited by abscisic acid
Abscisic acid
Abscisic acid , also known as abscisin II and dormin, is a plant hormone. ABA functions in many plant developmental processes, including bud dormancy. It is degraded by the enzyme -abscisic acid 8'-hydroxylase.-Function:...

.

Ethylene perception in plants


Ethylene could be perceived by a transmembrane protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 dimer
Protein dimer
In biochemistry, a dimer is a macromolecular complex formed by two, usually non-covalently bound, macromolecules like proteins or nucleic acids...

 complex. The gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

 encoding an ethylene receptor has been cloned in Arabidopsis thaliana
Arabidopsis thaliana
Arabidopsis thaliana is a small flowering plant native to Europe, Asia, and northwestern Africa. A spring annual with a relatively short life cycle, arabidopsis is popular as a model organism in plant biology and genetics...

and then in tomato
Tomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...

. Ethylene receptors are encoded by multiple genes in the Arabidopsis and tomato
Tomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...

 genomes. The gene family
Gene family
A gene family is a set of several similar genes, formed by duplication of a single original gene, and generally with similar biochemical functions...

 comprises five receptors in Arabidopsis and at least six in tomato, most of which have been shown to bind ethylene. DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 sequences for ethylene receptors have also been identified in many other plant species and an ethylene binding protein has even been identified in Cyanobacteria.

Environmental and biological triggers of ethylene


Environmental cues can induce the biosynthesis of the plant hormone. Flooding, drought, chilling, wounding, and pathogen attack can induce ethylene formation in the plant. In flooding, root suffers from lack of oxygen, or anoxia
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...

, which leads to the synthesis of 1-aminocyclopropane-1-carboxylic acid
1-Aminocyclopropane-1-carboxylic acid
1-Aminocyclopropane-1-carboxylic acid is a disubstituted cyclic alpha-amino acid in which a three-membered cyclopropane ring is fuzed to the C-atom of the amino acid....

 (ACC). ACC is transported upwards in the plant and then oxidized in leaves. The product, the ethylene causes epinasty of the leaves.

One speculation recently put forth for epinasty is the downward pointing leaves may act as pump handles in the wind. The ethylene may or may not additionally induce the growth of a valve in the xylem
Xylem
Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...

, but the idea would be that the plant would harness the power of the wind to pump out more water from the roots of the plants than would normally happen with transpiration
Transpiration
Transpiration is a process similar to evaporation. It is a part of the water cycle, and it is the loss of water vapor from parts of plants , especially in leaves but also in stems, flowers and roots. Leaf surfaces are dotted with openings which are collectively called stomata, and in most plants...

.

Physiological responses of plants


Like the other plant hormones, ethylene is considered to have pleiotropic effects. This essentially means that it is thought that at least some of the effects of the hormone are unrelated. What is actually caused by the gas may depend on the tissue affected as well as environmental conditions. In the evolution of plants, ethylene would simply be a message that was coopted for unrelated uses by plants during different periods of the evolutionary development.

List of plant responses to ethylene

  • Seedling triple response, thickening and shortening of hypocotyl
    Hypocotyl
    The hypocotyl is the stem of a germinating seedling, found below the cotyledons and above the radicle .-Dicots:...

     with pronounced apical hook.
  • In pollination
    Pollination
    Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...

    , when the pollen reaches the stigma, the precursor of the ethylene, ACC
    1-Aminocyclopropane-1-carboxylic acid
    1-Aminocyclopropane-1-carboxylic acid is a disubstituted cyclic alpha-amino acid in which a three-membered cyclopropane ring is fuzed to the C-atom of the amino acid....

    , is secreted to the petal, the ACC releases ethylene with ACC oxidase.
  • Stimulates leaf and flower senescence
    Senescence
    Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...

  • Stimulates senescence of mature xylem
    Xylem
    Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...

     cells in preparation for plant use
  • Induces leaf abscission
    Abscission
    Abscission is a term used in several areas of biology. In plant sciences it most commonly refers to the process by which a plant drops one or more of its parts, such as a leaf, fruit, flower or seed...

  • Induces seed germination
    Germination
    Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

  • Induces root hair
    Root hair
    A root hair, the rhizoid of a vascular plant, is a tubular outgrowth of a trichoblast, a hair-forming cell on the epidermis of a plant root. That is, root hairs are lateral extensions of a single cell and only rarely branched, thus invisible to the naked eye. They are found only in the region of...

     growth — increasing the efficiency of water and mineral absorption
  • Induces the growth of adventitious roots during flooding
  • Stimulates epinasty — leaf petiole
    Petiole (botany)
    In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...

     grows out, leaf hangs down and curls into itself
  • Stimulates fruit ripening
  • Induces a climacteric
    Climacteric (botany)
    The climacteric is a stage of fruit ripening associated with ethylene production and cell respiration rise. Apples, bananas, melons, apricots, tomatoes are climacteric fruit. Citrus, grapes, strawberries are non-climacteric...

     rise in respiration
    Cellular respiration
    Cellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate , and then release waste products. The reactions involved in respiration are catabolic reactions that involve...

     in some fruit which causes a release of additional ethylene.
  • Affects gravitropism
    Gravitropism
    Gravitropism is a turning or growth movement by a plant or fungus in response to gravity. Charles Darwin was one of the first to scientifically document that roots show positive gravitropism and stems show negative gravitropism. That is, roots grow in the direction of gravitational pull and stems...

  • Stimulates nutational bending
  • Inhibits stem growth and stimulates stem and cell broadening and lateral branch growth outside of seedling stage (see Hyponastic response
    Hyponastic response
    The hyponastic response is an upward bending of leaves or other plant parts, resulting from growth of the lower side. This can be observed in many terrestrial plants and is thought to be linked to the plant hormone ethylene....

    )
  • Interference with auxin
    Auxin
    Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by...

     transport (with high auxin
    Auxin
    Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by...

     concentrations)
  • Inhibits shoot growth and stoma
    Stoma
    In botany, a stoma is a pore, found in the leaf and stem epidermis that is used forgas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening...

    tal closing except in some water plants or habitually flooded ones such as some rice varieties, where the opposite occurs (conserving and )
  • Induces flowering in pineapple
    Pineapple
    Pineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...

    s
  • Inhibits short day induced flower initiation in Pharbitus nil and Chrysanthemum
    Chrysanthemum
    Chrysanthemums, often called mums or chrysanths, are of the genus constituting approximately 30 species of perennial flowering plants in the family Asteraceae which is native to Asia and northeastern Europe.-Etymology:...

     morifolium

Commercial issues


Ethylene shortens the shelf life of many fruits by hastening fruit ripening and floral senescence
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...

. Ethylene will shorten the shelf life of cut flowers and potted plants by accelerating floral senescence and floral abscission
Abscission
Abscission is a term used in several areas of biology. In plant sciences it most commonly refers to the process by which a plant drops one or more of its parts, such as a leaf, fruit, flower or seed...

. Flowers and plants which are subjected to stress during shipping, handling, or storage produce ethylene causing a significant reduction in floral display. Flowers affected by ethylene include carnation
Carnation
Dianthus caryophyllus is a species of Dianthus. It is probably native to the Mediterranean region but its exact range is unknown due to extensive cultivation for the last 2,000 years. It is the wild ancestor of the garden carnation.It is a herbaceous perennial plant growing to 80 cm tall...

, geranium
Pelargonium
Pelargonium is a genus of flowering plants which includes about 200 species of perennials, succulents, and shrubs, commonly known as scented geraniums or storksbills. Confusingly, Geranium is the correct botanical name of a separate genus of related plants often called Cranesbills. Both Geranium...

, petunia
Petunia
Petunia is a widely cultivated genus of flowering plants of South American origin, closely related with tobacco, cape gooseberries, tomatoes, deadly nightshades, potatoes and chili peppers; in the family Solanaceae. The popular flower derived its name from French, which took the word petun, meaning...

, rose
Rose
A rose is a woody perennial of the genus Rosa, within the family Rosaceae. There are over 100 species. They form a group of erect shrubs, and climbing or trailing plants, with stems that are often armed with sharp prickles. Flowers are large and showy, in colours ranging from white through yellows...

, and many others.

Ethylene can cause significant economic losses for florists, markets, suppliers, and growers. Researchers have developed several ways to inhibit ethylene, including inhibiting ethylene synthesis and inhibiting ethylene perception. Aminoethoxyvinylglycine (AVG), Aminooxyacetic acid
Aminooxyacetic acid
Aminooxyacetic acid, often abbreviated AOA or AOAA, is a compound that inhibits 4-aminobutyrate aminotransferase activity in vitro and in vivo, leading to less gamma-aminobutyric acid being broken down. Subsequently, the level of GABA is increased in tissues...

 (AOA), and silver ions are ethylene inhibitors. Inhibiting ethylene synthesis is less effective for reducing post-harvest losses since ethylene from other sources can still have an effect. By inhibiting ethylene perception, fruits, plants and flowers don't respond to ethylene produced endogenously or from exogenous sources. Inhibitors of ethylene perception include compounds that have a similar shape to ethylene, but do not elicit the ethylene response. One example of an ethylene perception inhibitor is 1-methylcyclopropene
1-Methylcyclopropene
1-Methylcyclopropene is a cyclopropene derivative used as a synthetic plant growth regulator. It is structurally related to the natural plant hormone ethylene and it is used commercially to slow down the ripening of fruit and to help maintain the freshness of cut flowers.-Chemical...

 (1-MCP).

Commercial growers of bromeliads, including pineapple
Pineapple
Pineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...

 plants, use ethylene to induce flowering. Plants can be induced to flower either by treatment with the gas in a chamber, or by placing a banana
Banana
Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....

 peel next to the plant in an enclosed area.

Chrysanthemum
Chrysanthemum
Chrysanthemums, often called mums or chrysanths, are of the genus constituting approximately 30 species of perennial flowering plants in the family Asteraceae which is native to Asia and northeastern Europe.-Etymology:...

 flowering is delayed by ethylene gas and growers have found that carbon dioxide 'burners' and the exhaust fumes from inefficient glasshouse heaters can raise the ethylene concentration to 0.05 vpm causing delay in flowering of commercial crops.

Historical significance


Many geologists and scholars believe that the famous Greek Oracle at Delphi
Delphi
Delphi is both an archaeological site and a modern town in Greece on the south-western spur of Mount Parnassus in the valley of Phocis.In Greek mythology, Delphi was the site of the Delphic oracle, the most important oracle in the classical Greek world, and a major site for the worship of the god...

 (the Pythia
Pythia
The Pythia , commonly known as the Oracle of Delphi, was the priestess at the Temple of Apollo at Delphi, located on the slopes of Mount Parnassus. The Pythia was widely credited for her prophecies inspired by Apollo. The Delphic oracle was established in the 8th century BC...

) went into her trance-like state as an effect of ethylene rising from ground faults.

History


Ethylene appears to have been discovered by Johann Joachim Becher, who obtained it by heating ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 with sulfuric acid; he mentioned the gas in his Physica Subterranea (1669). Joseph Priestley
Joseph Priestley
Joseph Priestley, FRS was an 18th-century English theologian, Dissenting clergyman, natural philosopher, chemist, educator, and political theorist who published over 150 works...

 also mentions the gas in his Experiments and observations relating to the various branches of natural philosophy: with a continuation of the observations on air (1779), where he reports that Jan Ingenhousz
Jan Ingenhousz
Jan Ingenhousz or Ingen-Housz FRS was a Dutch physiologist, biologist and chemist. He is best known for showing that light is essential to photosynthesis and thus having discovered photosynthesis. He also discovered that plants, like animals, have cellular respiration...

 saw ethylene synthesized in the same way by a Mr. Enée in Amsterdam in 1777 and that Ingenhousz subsequently produced the gas himself. The properties of ethylene were studied in 1795 by four Dutch
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 chemists, Johann Rudolph Deimann, Adrien Paets van Troostwyck, Anthoni Lauwerenburgh and Nicolas Bondt, who found that it differed from hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 gas and that it contained both carbon and hydrogen. This group also discovered that ethylene could be combined with chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 to produce the oil of the Dutch chemists, 1,2-dichloroethane
1,2-Dichloroethane
The chemical compound 1,2-dichloroethane, commonly known by its old name of ethylene dichloride , is a chlorinated hydrocarbon, mainly used to produce vinyl chloride monomer , the major precursor for PVC production. It is a colourless liquid with a chloroform-like odour...

; this discovery gave ethylene the name used for it at that time, olefiant gas (oil-making gas.)

In the mid-19th century, the suffix -ene (an Ancient Greek root added to the end of female names meaning "daughter of") was widely used to refer to a molecule or part thereof that contained one fewer hydrogen atoms than the molecule being modified. Thus, ethylene was the "daughter of ethyl
Ethyl group
In chemistry, an ethyl group is an alkyl substituent derived from ethane . It has the formula -C2H5 and is very often abbreviated -Et.Ethylation is the formation of a compound by introduction of the ethyl functional group, C2H5....

" . The name ethylene was used in this sense as early as 1852.

In 1866, the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 chemist August Wilhelm von Hofmann
August Wilhelm von Hofmann
August Wilhelm von Hofmann was a German chemist.-Biography:Hofmann was born at Gießen, Grand Duchy of Hesse. Not intending originally to devote himself to physical science, he first took up the study of law and philology at Göttingen. But he then turned to chemistry, and studied under Justus von...

 proposed a system of hydrocarbon nomenclature in which the suffixes -ane, -ene, -ine, -one, and -une were used to denote the hydrocarbons with 0, 2, 4, 6, and 8 fewer hydrogens than their parent alkane
Alkane
Alkanes are chemical compounds that consist only of hydrogen and carbon atoms and are bonded exclusively by single bonds without any cycles...

. In this system, ethylene became ethene. Hofmann's system eventually became the basis for the Geneva nomenclature approved by the International Congress of Chemists in 1892, which remains at the core of the IUPAC nomenclature. However, by that time, the name ethylene was deeply entrenched, and it remains in wide use today, especially in the chemical industry.

Nomenclature


The 1979 IUPAC nomenclature rules made an exception for retaining the non-systematic name ethylene, however, this decision was reversed in the 1993 rules so the IUPAC name is now ethene.

Safety


Like all hydrocarbons, ethylene is an asphyxiant
Asphyxiant gas
An asphyxiant gas is a non-toxic or minimally toxic gas which reduces or diplaces the normal oxygen concentration in breathing air. Prolonged breathing of oxygen depleted air can lead to death by asphyxiation...

 and combustible. It has been used as an anesthetic. It is listed as an IARC
IARC
IARC may refer to:* International Aerial Robotics Competition* International Agency for Research on Cancer* International Arctic Research Center* Israel Amateur Radio Club* iArc, South Korean architecture firm...

 class 3 carcinogen.

Appendix: ethylene production facilities


Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

  • Fort Saskatchewan, Fort Saskatchewan
    Fort Saskatchewan, Alberta
    Fort Saskatchewan is a city in Alberta, Canada, located northeast of downtown Edmonton, Alberta's capital city, along the North Saskatchewan River. Fort Saskatchewan is part of the Edmonton Census Metropolitan Area and is one of 24 municipalities on the Capital Region Board...

    , (Dow Chemical
  • Joffre, Joffre
    Joffre, Alberta
    Joffre is a hamlet in central Alberta, Canada within Lacombe County. It is located north of Highway 11, approximately northeast of Red Deer.- Demographics :The population of Joffre according to Lacombe County's 2008 municipal census is 195....

    , (Dow Chemical and Nova Chemicals
    NOVA Chemicals
    NOVA Chemicals Corporation is a plastics and chemical company headquartered in Calgary, Alberta, with Executive Offices in the Pittsburgh suburb of Moon Township, Pennsylvania and Lambton County, Ontario. It was founded in 1954 as Alberta Gas Trunk Lines and was later renamed to NOVA Corporation...

    ), 2165 kta ethylene


Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

  • Sarnia, Sarnia
    Sarnia, Ontario
    Sarnia is a city in Southern Ontario, Canada . It is the largest city on Lake Huron and is located where the upper Great Lakes empty into the St. Clair River....

    , (Nova Chemicals
    NOVA Chemicals
    NOVA Chemicals Corporation is a plastics and chemical company headquartered in Calgary, Alberta, with Executive Offices in the Pittsburgh suburb of Moon Township, Pennsylvania and Lambton County, Ontario. It was founded in 1954 as Alberta Gas Trunk Lines and was later renamed to NOVA Corporation...

    )


Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

  • Morris
    Morris, Illinois
    Morris is a city in Grundy County, Illinois, United States. The population was 13,636 at the 2010 census.Morris is home to the Dresden Nuclear Power Plant, which provides a substantial portion of the electricity supply for the Chicago metropolitan area...

    , Illinois
    Illinois
    Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

    , (LyondellBasell)


Louisiana
Louisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

  • Hahnville, Hahnville
    Hahnville, Louisiana
    Hahnville is a census-designated place in and the parish seat of St. Charles Parish, Louisiana, United States. The population was 2,792 at the 2000 census...

    , (Dow Chemical),
  • Lake Charles, Lake Charles
    Lake Charles, Louisiana
    Lake Charles is the fifth-largest incorporated city in the U.S. state of Louisiana, located on Lake Charles, Prien Lake, and the Calcasieu River. Located in Calcasieu Parish, a major cultural, industrial, and educational center in the southwest region of the state, and one of the most important in...

    , (Westlake Chemical),
  • Norco, Norco
    Norco, Louisiana
    Norco is a census-designated place in St. Charles Parish, Louisiana, United States. The population was 3,579 at the 2000 census. The community is home to a major Shell petroleum refinery. Its name is derived from the New Orleans Refining Company....

    , (Shell Chemical), 1500 kta ethylene


Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

  • Alvin, Alvin
    Alvin, Texas
    Alvin is a city in the U.S. state of Texas within the Houston–Sugar Land–Baytown metropolitan area and Brazoria County. As of the 2000 U.S. Census, the city population was 21,413. Alvin's claim to fame is Baseball Hall of Famer Nolan Ryan, who moved with his family to the city in 1947 as...

    , (Ineos
    Ineos
    INEOS Group Limited is a privately owned multinational chemicals company headquartered in Lausanne, Switzerland and with its registered office in Lyndhurst, United Kingdom...

    )
  • Baytown
    Baytown, Texas
    Baytown is a city within Harris County and partially in Chambers County in the Gulf Coast region of the U.S. state of Texas. Located within the Houston–Sugar Land–Baytown metropolitan area, it lies along both State Highway 146 and Interstate 10. As of 2010, Baytown had an population of 71,802...

    , (Chevron Chemicals Company), Cedar Bayou Plant, not available kta ethylene
  • Channelview, Channelview
    Channelview, Texas
    Channelview is a census-designated place in the U.S. state of Texas within the Houston–Sugar Land–Baytown metropolitan area and Harris County. The population was 29,685 at the 2000 census...

    , (LyondellBasell), 1450 kta ethylene
  • Corpus Christi, Corpus Christi
    Corpus Christi, Texas
    Corpus Christi is a coastal city in the South Texas region of the U.S. state of Texas. The county seat of Nueces County, it also extends into Aransas, Kleberg, and San Patricio counties. The MSA population in 2008 was 416,376. The population was 305,215 at the 2010 census making it the...

    , (LyondellBasell),
  • Deer Park, Deer Park
    Deer Park, Texas
    Deer Park is a city in the U.S. state of Texas within the Houston–Sugar Land–Baytown metropolitan area. The city is located in Harris County and is situated in Southeast Texas. As of the 2010 U.S. Census, the population of Deer Park was 32,010....

    , (Shell Chemical), 1200 kta ethylene
  • Orange, Orange
    Orange, Texas
    Orange is a city in Orange County, Texas, United States. As of the 2000 census, the city population was 18,643. It is the county seat of Orange County, and is the easternmost city in Texas. Located on the Sabine River at the border with Louisiana, it is part of the Beaumont–Port Arthur...

    , (DuPont
    DuPont
    E. I. du Pont de Nemours and Company , commonly referred to as DuPont, is an American chemical company that was founded in July 1802 as a gunpowder mill by Eleuthère Irénée du Pont. DuPont was the world's third largest chemical company based on market capitalization and ninth based on revenue in 2009...

    ),
  • Port Arthur, Port Arthur
    Port Arthur, Texas
    -Demographics:As of the 2000 census, there were 57,755 people, 21,839 households, and 14,675 families residing in the city. The population density was 696.5 people per square mile . There were 24,713 housing units at an average density of 298.0 per square mile...

    , (BASF and Total Petrochemical)


Nanhai, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

  • Nanhai, Nanhai, (Shell Chemical), not available kta ethylene


Ras Laffan Industrial City
Ras Laffan Industrial City
Ras Laffan Industrial City is an industrial hub located north of Doha, Qatar. It is administrated by Qatar Petroleum.Ras Laffan Industrial City is the Qatar's main site for production of liquefied natural gas and gas-to-liquid...

, Qatar
Qatar
Qatar , also known as the State of Qatar or locally Dawlat Qaṭar, is a sovereign Arab state, located in the Middle East, occupying the small Qatar Peninsula on the northeasterly coast of the much larger Arabian Peninsula. Its sole land border is with Saudi Arabia to the south, with the rest of its...

  • Ras Laffan Industrial City
    Ras Laffan Industrial City
    Ras Laffan Industrial City is an industrial hub located north of Doha, Qatar. It is administrated by Qatar Petroleum.Ras Laffan Industrial City is the Qatar's main site for production of liquefied natural gas and gas-to-liquid...

    , Ras Laffan Industrial City, (QAPCO), 1300 kta ethylene

  • National Iranian Petrochemical Company
    National Iranian Petrochemical Company
    The National Iranian Petrochemical Company , a subsidiary to the Iranian Petroleum Ministry, is owned by the government of the Islamic Republic of Iran. It is responsible for the development and operation of the country's petrochemical sector. Founded in 1964, NIPC began its activities by operating...

    , 1320 kta ethylene

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