Ethylene ( IUPAC name: ethene ) is a hydrocarbon which has the formula C 2 H 4 or H 2 C=CH 2 . It is a colourless, flammable gas with a faint "sweet and musky " odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon double bonds ).
49-480: Ethylene is widely used in the chemical industry, and its worldwide production (over 150 million tonnes in 2016) exceeds that of any other organic compound . 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
98-538: A Germanic word in general use in the North Sea area since the Middle Ages (cf. Old English and Old Frisian tunne , Old High German and Medieval Latin tunna , German and French tonne ) to designate a large cask, or tun . A full tun, standing about a metre high, could easily weigh a tonne. See also the common German word de:Mülltonne (literal translation: garbage drum ). The spelling tonne pre-dates
147-516: A Lewis acidic catalyst is used, such as ferric chloride . Many detailed procedures are available. Because fluorine is so reactive , other methods, such as the Balz–Schiemann reaction , are used to prepare fluorinated aromatic compounds. In the Hunsdiecker reaction , carboxylic acids are converted to organic halide , whose carbon chain is shortened by one carbon atom with respect to
196-435: A niche use is as an anesthetic agent (in an 85% ethylene/15% oxygen ratio). Another use is as a welding gas. It is also used as a refrigerant gas for low temperature applications under the name R-1150. Global ethylene production was 107 million tonnes in 2005, 109 million tonnes in 2006, 138 million tonnes in 2010, and 141 million tonnes in 2011. By 2013, ethylene was produced by at least 117 companies in 32 countries. To meet
245-534: A precursor to propionic acid and n-propyl alcohol . 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 : 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
294-575: A special category with respect to halogenation. Most organic compounds, saturated or otherwise, burn upon contact with F 2 , ultimately yielding carbon tetrafluoride . By contrast, the heavier halogens are far less reactive toward saturated hydrocarbons. Highly specialised conditions and apparatus are required for fluorinations with elemental fluorine . Commonly, fluorination reagents are employed instead of F 2 . Such reagents include cobalt trifluoride , chlorine trifluoride , and iodine pentafluoride . The method electrochemical fluorination
343-490: Is a chemical reaction which introduces one or more halogens into a chemical compound . Halide -containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers , drugs . This kind of conversion is in fact so common that a comprehensive overview is challenging. This article mainly deals with halogenation using elemental halogens ( F 2 , Cl 2 , Br 2 , I 2 ). Halides are also commonly introduced using salts of
392-536: Is a substitution reaction . The reaction typically involves free radical pathways. The regiochemistry of the halogenation of alkanes is largely determined by the relative weakness of the C–H bonds . This trend is reflected by the faster reaction at tertiary and secondary positions. Free radical chlorination is used for the industrial production of some solvents : Naturally-occurring organobromine compounds are usually produced by free radical pathway catalyzed by
441-483: 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. Tonne The tonne ( / t ʌ n / or / t ɒ n / ; symbol: t ) is a unit of mass equal to 1,000 kilograms . It is a non-SI unit accepted for use with SI . It is also referred to as a metric ton in the United States to distinguish it from
490-415: Is also an important natural plant hormone and is used in agriculture to induce ripening of fruits . 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
539-598: Is also official for the metric ton in the United States, having been adopted by the United States National Institute of Standards and Technology (NIST). It is a symbol, not an abbreviation, and should not be followed by a period . Use of lower case is significant, and use of other letter combinations can lead to ambiguity. For example, T, MT, mT, are the SI symbols for the tesla , megatesla, and millitesla, respectively, while Mt and mt are SI-compatible symbols for
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#1732855871909588-476: 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. 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
637-460: Is influenced by the halogen. Fluorine and chlorine are more electrophilic and are more aggressive halogenating agents. Bromine is a weaker halogenating agent than both fluorine and chlorine, while iodine is the least reactive of them all. The facility of dehydrohalogenation follows the reverse trend: iodine is most easily removed from organic compounds, and organofluorine compounds are highly stable. Halogenation of saturated hydrocarbons
686-507: Is not. Nevertheless, use of the name ethylene for H 2 C=CH 2 (and propylene for H 2 C=CHCH 3 ) is still prevalent among chemists in North America. "A key factor affecting petrochemicals life-cycle emissions is the methane intensity of feedstocks, especially in the production segment." Emissions from cracking of naptha and natural gas (common in the US as gas is cheap there) depend a lot on
735-400: 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. Ethylene is oxidized to produce ethylene oxide , a key raw material in
784-409: Is rarely synthesized in the laboratory and is ordinarily purchased. It can be produced via dehydration of ethanol with sulfuric acid or in the gas phase with aluminium oxide or activated alumina . Ethylene is produced from methionine in nature. The immediate precursor is 1-aminocyclopropane-1-carboxylic acid . Ethylene is a fundamental ligand in transition metal alkene complexes . One of
833-400: Is the joule . One tonne of TNT is approximately equivalent to 4.2 gigajoules. In the petroleum industry the tonne of oil equivalent (toe) is a unit of energy : the amount of energy released by burning one tonne of crude oil , approximately 42 GJ. There are several slightly different definitions. This is ten times as much as a tonne of TNT because atmospheric oxygen is used. Like
882-491: Is the feedstock, ethylene is the product. Ethylene is separated from the resulting mixture by repeated compression and distillation . 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). Other technologies employed for the production of ethylene include Fischer-Tropsch synthesis and methanol-to-olefins (MTO). Although of great value industrially, ethylene
931-587: Is the route to the anesthetic halothane from trichloroethylene : Iodination and bromination can be effected by the addition of iodine and bromine to alkenes. The reaction, which conveniently proceeds with the discharge of the color of I 2 and Br 2 , is the basis of the analytical method . The iodine number and bromine number are measures of the degree of unsaturation for fats and other organic compounds. Aromatic compounds are subject to electrophilic halogenation : This kind of reaction typically works well for chlorine and bromine . Often
980-402: Is used commercially for the production of perfluorinated compounds . It generates small amounts of elemental fluorine in situ from hydrogen fluoride . The method avoids the hazards of handling fluorine gas. Many commercially important organic compounds are fluorinated using this technology. Unsaturated compounds , especially alkenes and alkynes , add halogens: In oxychlorination ,
1029-457: The Dutch oil , 1,2-dichloroethane ; this discovery gave ethylene the name used for it at that time, olefiant gas (oil-making gas.) 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. In the mid-19th century, the suffix -ene (an Ancient Greek root added to the end of female names meaning "daughter of")
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#17328558719091078-457: The United States and Europe , approximately 90% of ethylene is used to produce ethylene oxide , ethylene dichloride , ethylbenzene and polyethylene . Most of the reactions with ethylene are electrophilic addition . 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
1127-505: 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 . The hydroformylation (oxo reaction) of ethylene results in propionaldehyde ,
1176-413: The enzyme bromoperoxidase . The reaction requires bromide in combination with oxygen as an oxidant . The oceans are estimated to release 1–2 million tons of bromoform and 56,000 tons of bromomethane annually. The iodoform reaction , which involves degradation of methyl ketones , proceeds by the free radical iodination. Because of its extreme reactivity, fluorine ( F 2 ) represents
1225-402: The gram and the kilogram, the tonne gave rise to a (now obsolete) force unit of the same name, the tonne-force, equivalent to about 9.8 kilonewtons . The unit is also often called simply "tonne" or "metric ton" without identifying it as a unit of force. In contrast to the tonne as a mass unit, the tonne-force is not accepted for use with SI. Halogenation In chemistry , halogenation
1274-401: The non-metric units of the short ton ( United States customary units ) and the long ton ( British imperial units ). It is equivalent to approximately 2,204.6 pounds , 1.102 short tons, and 0.984 long tons. The official SI unit is the megagram ( Mg ), a less common way to express the same amount. The BIPM symbol for the tonne is t, adopted at the same time as the unit in 1879. Its use
1323-510: The tonne and the spelling of ton in English is the same, though they differ in mass. One tonne is equivalent to: A tonne is the mass of one cubic metre of pure water at 4 °C (39 °F). As a non-SI unit, the use of SI metric prefixes with the tonne does not fall within the SI standard. For multiples of the tonne, it is more usual to speak of thousands or millions of tonnes. Kilotonne, megatonne, and gigatonne are more usually used for
1372-503: The IFP process produces 1-butene . 1-Butene is used as a comonomer in the production of certain kinds of polyethylene . Ethylene is a hormone that affects the ripening and flowering of many plants. It is widely used to control freshness in horticulture and fruits . The scrubbing of naturally occurring ethylene delays ripening. Adsorption of ethylene by nets coated in titanium dioxide gel has also been shown to be effective. An example of
1421-496: The United States. It traditionally referred to a metric ton of ore containing 1% (i.e. 10 kg) of metal. The following excerpt from a mining geology textbook describes its usage in the particular case of tungsten: Tungsten concentrates are usually traded in metric tonne units (originally designating one tonne of ore containing 1% of WO 3 , today used to measure WO 3 quantities in 10 kg units. One metric tonne unit (mtu) of tungsten (VI) contains 7.93 kilograms of tungsten. In
1470-454: The carbon chain of the particular carboxylic acid. The carboxylic acid is first converted to its silver salt, which is then oxidized with halogen : Many organometallic compounds react with halogens to give the organic halide: All elements aside from argon , neon , and helium form fluorides by direct reaction with fluorine . Chlorine is slightly more selective, but still reacts with most metals and heavier nonmetals . Following
1519-641: The case of uranium , MTU is sometimes used in the sense of metric ton of uranium (1,000 kg [2,200 lb]). The tonne of trinitrotoluene (TNT) is used as a proxy for energy, usually of explosions (TNT is a common high explosive ). Prefixes are used: kiloton(ne), megaton(ne), gigaton(ne), especially for expressing nuclear weapon yield , based on a specific combustion energy of TNT of about 4.2 MJ / kg (or one thermochemical calorie per milligram ). Hence, 1 t TNT = approx. 4.2 GJ , 1 kt TNT = approx. 4.2 TJ , 1 Mt TNT = approx. 4.2 PJ . The SI unit of energy
Ethylene - Misplaced Pages Continue
1568-426: The combination of hydrogen chloride and oxygen serves as the equivalent of chlorine , as illustrated by this route to 1,2-dichloroethane : The addition of halogens to alkenes proceeds via intermediate halonium ions . In special cases, such intermediates have been isolated. Bromination is more selective than chlorination because the reaction is less exothermic . Illustrative of the bromination of an alkene
1617-515: The common and recommended pronunciation is / t ɒ n / . In the United States, metric ton is the name for this unit used and recommended by NIST; an unqualified mention of a ton typically refers to a short ton of 2,000 lb (907.2 kg) and to a lesser extent to a long ton of 2,240 lb (1,016 kg), with the term tonne rarely used in speech or writing. Both terms are acceptable in Canadian English . Ton and tonne are both derived from
1666-401: The energy of nuclear explosions and other events in equivalent mass of TNT , often loosely as approximate figures. When used in this context, there is little need to distinguish between metric and other tons, and the unit is spelled either as ton or tonne with the relevant prefix attached. A metric ton unit (mtu) can mean 10 kg (22 lb) within metal trading, particularly within
1715-414: The ethylene using both the π and π* orbitals. Being a simple molecule, ethylene is spectroscopically simple. Its UV-vis spectrum is still used as a test of theoretical methods. 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
1764-602: The ever-increasing demand for ethylene, sharp increases in production facilities are added globally, particularly in the Mideast and in China . Production emits greenhouse gas , namely significant amounts of carbon dioxide. 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
1813-673: The first organometallic compounds, Zeise's salt is a complex of ethylene. Useful reagents containing ethylene include Pt(PPh 3 ) 2 (C 2 H 4 ) and Rh 2 Cl 2 (C 2 H 4 ) 4 . The Rh-catalysed hydroformylation of ethylene is conducted on an industrial scale to provide propionaldehyde . 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. Ethylene appears to have been discovered by Johann Joachim Becher , who obtained it by heating ethanol with sulfuric acid; he mentioned
1862-809: The gas in his Physica Subterranea (1669). 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. 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. This group also discovered that ethylene could be combined with chlorine to produce
1911-422: The halides and halogen acids. Many specialized reagents exist for and introducing halogens into diverse substrates , e.g. thionyl chloride . Several pathways exist for the halogenation of organic compounds, including free radical halogenation , ketone halogenation , electrophilic halogenation , and halogen addition reaction . The nature of the substrate determines the pathway. The facility of halogenation
1960-529: The initial complexation of ethylene to a Pd(II) center. 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 . Major chemical intermediates from
2009-588: The introduction of the SI in 1960; it has been used with this meaning in France since 1842, when there were no metric prefixes for multiples of 10 and above, and is now used as the standard spelling for the metric mass measurement in most English -speaking countries. In the United States, the unit was originally referred to using the French words millier or tonneau , but these terms are now obsolete. The British imperial and United States customary units are comparable to
Ethylene - Misplaced Pages Continue
2058-464: The megatonne (one teragram) and millitonne (one kilogram). If describing TNT equivalent units of energy, one megatonne of TNT is equivalent to approximately 4.184 petajoules . In English, tonne is an established spelling alternative to metric ton . In the United States and United Kingdom, tonne is usually pronounced the same as ton ( / t ʌ n / ), but the final "e" can also be pronounced, i.e. " tunnie " ( / ˈ t ʌ n i / ). In Australia,
2107-508: 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, ethylene was used as an anesthetic. 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. The 1979 IUPAC nomenclature rules made an exception for retaining
2156-466: The non-systematic name ethylene ; however, this decision was reversed in the 1993 rules, and it remains unchanged in the newest 2013 recommendations, so the IUPAC name is now ethene . In the IUPAC system, the name ethylene is reserved for the divalent group -CH 2 CH 2 -. Hence, names like ethylene oxide and ethylene dibromide are permitted, but the use of the name ethylene for the two-carbon alkene
2205-441: 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 . Ethylene oxidation in the presence of a palladium catalyst can form acetaldehyde . This conversion remains a major industrial process (10M kg/y). The process proceeds via
2254-513: The source of energy (for example gas burnt to provide high temperatures) but that from naptha is certainly more per kg of feedstock. Both steam cracking and production from natural gas via ethane are estimated to emit 1.8 to 2kg of CO2 per kg ethylene produced, totalling over 260 million tonnes a year. This is more than all other manufactured chemicals except cement and ammonia. According to a 2022 report using renewable or nuclear energy could cut emissions by almost half. Like all hydrocarbons, ethylene
2303-563: 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 . 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,
2352-405: The usual trend, bromine is less reactive and iodine least of all. Of the many reactions possible, illustrative is the formation of gold(III) chloride by the chlorination of gold . The chlorination of metals is usually not very important industrially since the chlorides are more easily made from the oxides and hydrogen chloride . Where chlorination of inorganic compounds is practiced on
2401-449: 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 2 H 4 ) was the "daughter of ethyl " ( C 2 H 5 ). The name ethylene was used in this sense as early as 1852. In 1866, the German chemist August Wilhelm von Hofmann proposed a system of hydrocarbon nomenclature in which
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