Names | |||
---|---|---|---|
Preferred IUPAC name Ethene [1] | |||
Systematic IUPAC name Ethene | |||
Other names Refrigerant R-1150 | |||
Identifiers | |||
3D model (JSmol) | |||
1730731 | |||
ChEBI | |||
ChEMBL | |||
ChemSpider | |||
ECHA InfoCard | 100.000.742 | ||
EC Number |
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214 | |||
KEGG | |||
PubChem CID | |||
RTECS number |
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UNII | |||
UN number | 1962 1038 | ||
CompTox Dashboard (EPA) | |||
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Properties | |||
C 2H 4 | |||
Molar mass | 28.054 g·mol−1 | ||
Appearance | colourless gas | ||
Density | 1.178 kg/m3 at 15 °C, gas [2] | ||
Melting point | −169.2 °C (−272.6 °F; 104.0 K) | ||
Boiling point | −103.7 °C (−154.7 °F; 169.5 K) | ||
131 mg/L (25 °C); [3] 2.9 mg/L [4] | |||
Solubility in ethanol | 4.22 mg/L [4] | ||
Solubility in diethyl ether | good [4] | ||
Acidity (pKa) | 44 | ||
Conjugate acid | Ethenium | ||
-15.30·10−6 cm3/mol | |||
Viscosity | 10.28 μPa·s [5] | ||
Structure | |||
D2h | |||
zero | |||
Thermochemistry | |||
Std molar entropy (S⦵298) | 219.32 J·K−1·mol−1 | ||
Std enthalpy of formation (ΔfH⦵298) | +52.47 kJ/mol | ||
Hazards | |||
GHS labelling: | |||
Danger | |||
H220, H336 | |||
P210, P261, P271, P304+P340, P312, P377, P381, P403, P403+P233, P405, P501 | |||
NFPA 704 (fire diamond) | |||
Flash point | −136 °C (−213 °F; 137 K) | ||
542.8 °C (1,009.0 °F; 815.9 K) | |||
Safety data sheet (SDS) | ICSC 0475 | ||
Related compounds | |||
Related compounds | Ethane Acetylene Propene | ||
Supplementary data page | |||
Ethylene (data page) | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula C2H4 or H2C=CH2. It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. [7] It is the simplest alkene (a hydrocarbon with carbon–carbon double bonds).
Ethylene is widely used in the chemical industry, and its worldwide production (over 150 million tonnes in 2016 [8] ) exceeds that of any other organic compound. [9] [10] Much of this production goes toward creating polythene, which is a widely used plastic containing polymer chains of ethylene units in various chain lengths. Production emits greenhouse gases, including methane from feedstock production and carbon dioxide from any non-sustainable energy used.
Ethylene is also an important natural plant hormone and is used in agriculture to induce ripening of fruits. [11] The hydrate of ethylene is ethanol.
This hydrocarbon has four hydrogen atoms bound to a pair of carbon atoms that are connected by a double bond. All six atoms that comprise ethylene are coplanar. The H-C-H angle is 117.4°, close to the 120° for ideal sp² hybridized carbon. The molecule is also relatively weak: rotation about the C-C bond is a very low energy process that requires breaking the π-bond by supplying heat at 50 °C.[ citation needed ]
The π-bond in the ethylene molecule is responsible for its useful reactivity. The double bond is a region of high electron density, 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.[ citation needed ]
Being a simple molecule, ethylene is spectroscopically simple. Its UV-vis spectrum is still used as a test of theoretical methods. [12]
Major industrial reactions of ethylene include in order of scale: 1) polymerization, 2) oxidation, 3) halogenation and hydrohalogenation, 4) alkylation, 5) hydration, 6) oligomerization, and 7) hydroformylation. In the United States and Europe, approximately 90% of ethylene is used to produce ethylene oxide, ethylene dichloride, ethylbenzene and polyethylene. [13] Most of the reactions with ethylene are electrophilic addition.[ citation needed ]
Polyethylene production uses more than half of the world's ethylene supply. Polyethylene, also called polyethene and polythene, is the world's most widely used plastic. It is primarily used to make films in packaging, carrier bags and trash liners. Linear alpha-olefins, produced by oligomerization (formation of short-chain molecules) are used as precursors, detergents, plasticisers, synthetic lubricants, additives, and also as co-monomers in the production of polyethylenes. [13]
Ethylene is oxidized to produce ethylene oxide, a key raw material in the production of surfactants and detergents by ethoxylation. Ethylene oxide is also hydrolyzed to produce ethylene glycol, widely used as an automotive antifreeze as well as higher molecular weight glycols, glycol ethers, and polyethylene terephthalate. [14] [15]
Ethylene oxidation in the presence of a palladium catalyst can form acetaldehyde. This conversion remains a major industrial process (10M kg/y). [16] The process proceeds via the initial complexation of ethylene to a Pd(II) center.[ citation needed ]
Major intermediates from the halogenation and hydrohalogenation 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, trichloroethylene, perchloroethylene, methyl chloroform, polyvinylidene chloride and copolymers, and ethyl bromide. [17]
Major chemical intermediates from the alkylation with ethylene is ethylbenzene, precursor to styrene. Styrene is used principally in polystyrene for packaging and insulation, as well as in styrene-butadiene rubber for tires and footwear. On a smaller scale, ethyltoluene, ethylanilines, 1,4-hexadiene, and aluminium alkyls. Products of these intermediates include polystyrene, unsaturated polyesters and ethylene-propylene terpolymers. [17]
The hydroformylation (oxo reaction) of ethylene results in propionaldehyde, a precursor to propionic acid and n-propyl alcohol. [17]
Ethylene has long represented the major nonfermentative precursor to ethanol. The original method entailed its conversion to diethyl sulfate, followed by hydrolysis. The main method practiced since the mid-1990s is the direct hydration of ethylene catalyzed by solid acid catalysts: [18]
Ethylene is dimerized by hydrovinylation to give n-butenes using processes licensed by Lummus or IFP. The Lummus process produces mixed n-butenes (primarily 2-butenes) while the IFP process produces 1-butene. 1-Butene is used as a comonomer in the production of certain kinds of polyethylene. [19]
Ethylene is a hormone that affects the ripening and flowering of many plants. It is widely used to control freshness in horticulture and fruits. [20] The scrubbing of naturally occurring ethylene delays ripening. [21] Adsorption of ethylene by nets coated in titanium dioxide gel has also been shown to be effective. [22]
An example of a niche use is as an anesthetic agent (in an 85% ethylene/15% oxygen ratio). [23] Another use is as a welding gas. [13] [24] It is also used as a refrigerant gas for low temperature applications under the name R-1150. [25]
Global ethylene production was 107 million tonnes in 2005, [9] 109 million tonnes in 2006, [26] 138 million tonnes in 2010, and 141 million tonnes in 2011. [27] By 2013, ethylene was produced by at least 117 companies in 32 countries. To meet the ever-increasing demand for ethylene, sharp increases in production facilities are added globally, particularly in the Mideast and in China. [28] Production emits greenhouse gas, namely significant amounts of carbon dioxide. [29]
Ethylene is produced by several methods in the petrochemical industry. A primary method is steam cracking (SC) where hydrocarbons and steam are heated to 750–950 °C. This process converts large hydrocarbons into smaller ones and introduces unsaturation. When ethane is the feedstock, ethylene is the product. Ethylene is separated from the resulting mixture by repeated compression and distillation. [17] In Europe and Asia, ethylene is obtained mainly from cracking naphtha, gasoil and condensates with the coproduction of propylene, C4 olefins and aromatics (pyrolysis gasoline). [30] Other technologies employed for the production of ethylene include Fischer-Tropsch synthesis and methanol-to-olefins (MTO). [31]
Although of great value industrially, ethylene is rarely synthesized in the laboratory and is ordinarily purchased. [32] It can be produced via dehydration of ethanol with sulfuric acid or in the gas phase with aluminium oxide or activated alumina. [33]
Ethylene is produced from methionine in nature. The immediate precursor is 1-aminocyclopropane-1-carboxylic acid. [34]
Ethylene is a fundamental ligand in transition metal alkene complexes. One of the first organometallic compounds, Zeise's salt is a complex of ethylene. Useful reagents containing ethylene include Pt(PPh3)2(C2H4) and Rh2Cl2(C2H4)4. The Rh-catalysed hydroformylation of ethylene is conducted on an industrial scale to provide propionaldehyde. [36]
Some geologists and scholars believe that the famous Greek Oracle at Delphi (the Pythia) went into her trance-like state as an effect of ethylene rising from ground faults. [37]
Ethylene appears to have been discovered by Johann Joachim Becher, who obtained it by heating ethanol with sulfuric acid; [38] he mentioned the gas in his Physica Subterranea (1669). [39] Joseph Priestley 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 saw ethylene synthesized in the same way by a Mr. Enée in Amsterdam in 1777 and that Ingenhousz subsequently produced the gas himself. [40] The properties of ethylene were studied in 1795 by four Dutch chemists, Johann Rudolph Deimann, Adrien Paets van Troostwyck, Anthoni Lauwerenburgh and Nicolas Bondt, who found that it differed from hydrogen gas and that it contained both carbon and hydrogen. [41] This group also discovered that ethylene could be combined with chlorine to produce the Dutch oil, 1,2-dichloroethane; this discovery gave ethylene the name used for it at that time, olefiant gas (oil-making gas.) [42] The term olefiant gas is in turn the etymological origin of the modern word "olefin", the class of hydrocarbons in which ethylene is the first member.[ citation needed ]
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 (C
2H
4) was the "daughter of ethyl" (C
2H
5). The name ethylene was used in this sense as early as 1852. [43]
In 1866, the German chemist August Wilhelm von Hofmann 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. [44] 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.
Following experimentation by Luckhardt, Crocker, and Carter at the University of Chicago, [45] ethylene was used as an anesthetic. [46] [7] It remained in use through the 1940s use even while chloroform was being phased out. Its pungent odor and its explosive nature limit its use today. [47]
The 1979 IUPAC nomenclature rules made an exception for retaining the non-systematic name ethylene; [48] however, this decision was reversed in the 1993 rules, [49] and it remains unchanged in the newest 2013 recommendations, [50] so the IUPAC name is now ethene. In the IUPAC system, the name ethylene is reserved for the divalent group -CH2CH2-. Hence, names like ethylene oxide and ethylene dibromide are permitted, but the use of the name ethylene for the two-carbon alkene is not. Nevertheless, use of the name ethylene for H2C=CH2 (and propylene for H2C=CHCH3) is still prevalent among chemists in North America. [51]
"A key factor affecting petrochemicals life-cycle emissions is the methane intensity of feedstocks, especially in the production segment." [52] Emissions from cracking of naptha and natural gas (common in the US as gas is cheap there) depend a lot on the source of energy (for example gas burnt to provide high temperatures [53] ) but that from naptha is certainly more per kg of feedstock. [54] Both steam cracking and production from natural gas via ethane are estimated to emit 1.8 to 2kg of CO2 per kg ethylene produced, [55] totalling over 260 million tonnes a year. [56] This is more than all other manufactured chemicals except cement and ammonia. [57] According to a 2022 report using renewable or nuclear energy could cut emissions by almost half. [54]
Like all hydrocarbons, ethylene is a combustible asphyxiant. It is listed as an IARC group 3 agent, since there is no current evidence that it causes cancer in humans. [58]
In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl functional group bound to a saturated carbon atom. Alcohols range from the simple, like methanol and ethanol, to complex, like sugars and cholesterol. The presence of an OH group strongly modifies the properties of hydrocarbons, conferring hydrophilic (water-loving) properties. The OH group provides a site at which many reactions can occur.
In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.
Ethanol is an organic compound with the chemical formula CH3CH2OH. It is an alcohol, with its formula also written as C2H5OH, C2H6O or EtOH, where Et stands for ethyl. Ethanol is a volatile, flammable, colorless liquid with a characteristic wine-like odor and pungent taste. In nature, grape-sugar breaks up by the action of fermentation into alcohol or carbonic acid, without anything being added. As a psychoactive depressant, it is the active ingredient in alcoholic beverages, and the second most consumed drug globally behind caffeine.
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic; their odor is usually faint, and may be similar to that of gasoline or lighter fluid. They occur in a diverse range of molecular structures and phases: they can be gases, liquids, low melting solids or polymers.
Petrochemicals are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as maize, palm fruit or sugar cane.
Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bottles, cups, jars, etc.). As of 2017, over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market.
Ethylene glycol is an organic compound with the formula (CH2OH)2. It is mainly used for two purposes: as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odorless, colorless, flammable, viscous liquid. It has a sweet taste, but is toxic in high concentrations. This molecule has been observed in outer space.
Ethane is a naturally occurring organic chemical compound with chemical formula C
2H
6. At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining. Its chief use is as feedstock for ethylene production. The ethyl group is formally, although rarely practically, derived from ethane.
Isobutane, also known as i-butane, 2-methylpropane or methylpropane, is a chemical compound with molecular formula HC(CH3)3. It is an isomer of butane. Isobutane is a colorless, odorless gas. It is the simplest alkane with a tertiary carbon atom. Isobutane is used as a precursor molecule in the petrochemical industry, for example in the synthesis of isooctane.
In chemistry, a hydration reaction is a chemical reaction in which a substance combines with water. In organic chemistry, water is added to an unsaturated substrate, which is usually an alkene or an alkyne. This type of reaction is employed industrially to produce ethanol, isopropanol, and butan-2-ol.
Ethylene oxide is an organic compound with the formula C2H4O. It is a cyclic ether and the simplest epoxide: a three-membered ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sweet odor. Because it is a strained ring, ethylene oxide easily participates in a number of addition reactions that result in ring-opening. Ethylene oxide is isomeric with acetaldehyde and with vinyl alcohol. Ethylene oxide is industrially produced by oxidation of ethylene in the presence of a silver catalyst.
1,3-Butadiene is the organic compound with the formula CH2=CH-CH=CH2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two vinyl groups. It is the simplest conjugated diene.
Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petroleum-like odor.
Isobutylene is a hydrocarbon with the chemical formula (CH3)2C=CH2. It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. It is a colorless flammable gas, and is of considerable industrial value.
In organic chemistry, olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds. Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions. For their elucidation of the reaction mechanism and their discovery of a variety of highly active catalysts, Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock were collectively awarded the 2005 Nobel Prize in Chemistry.
In organic chemistry, terminal alkenes are a family of organic compounds which are alkenes with a chemical formula CxH2x, distinguished by having a double bond at the primary, alpha (α), or 1- position. This location of a double bond enhances the reactivity of the compound and makes it useful for a number of applications.
Straight-chain terminal alkenes, also called linear alpha olefins (LAO) or normal alpha olefins (NAO), are alkenes (olefins) having a chemical formula CnH2n, distinguished from other alkenes with a similar molecular formula by being terminal alkenes, in which the double bond occurs at the alpha position, and by having a linear (unbranched) hydrocarbon chain.
1-Butene (IUPAC name: But-1-ene, also known as 1-butylene) is the organic compound with the formula CH3CH2CH=CH2. It is a colorless gas. But-1-ene is an alkene easily condensed to give a colorless liquid. It is classified as a linear alpha-olefin (terminal alkene). It is one of the isomers of butene (butylene). It is a precursor to diverse products.
Acetic acid, systematically named ethanoic acid, is an acidic, colourless liquid and organic compound with the chemical formula CH3COOH. Vinegar is at least 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. It has been used, as a component of vinegar, throughout history from at least the third century BC.
Isopropyl alcohol is a colorless, flammable organic compound with a pungent alcoholic odor.