Ethenolysis

Last updated

In organic chemistry, ethenolysis is a chemical process in which internal olefins are degraded using ethylene (H2C=CH2) as the reagent. The reaction is an example of cross metathesis. The utility of the reaction is driven by the low cost of ethylene as a reagent and its selectivity. It produces compounds with terminal alkene functional groups (α-olefins), which are more amenable to other reactions such as polymerization and hydroformylation.

Contents

The general reaction equation is:

Ethenolysis is a form of methylenation, i.e., the installation of methylene (−CH2−) groups.

Applications

Terminal alkenes

Using ethenolysis, higher molecular weight internal alkenes can be converted to more valuable terminal alkenes. The Shell higher olefin process (SHOP process) uses ethenolysis on an industrial scale. SHOP α-olefin mixtures are first separated by distillation. Higher molecular weight fractions are isomerized by alkaline alumina catalysts in the liquid phase. The resulting internal olefins are reacted with ethylene to regenerate α-olefins. The large excess of ethylene moves the reaction equilibrium to the terminal α-olefins. Catalysts are often prepared from rhenium(VII) oxide (Re2O7) supported on alumina. [1]

Perfume

In one application, neohexene, a precursor to perfumes, is prepared by ethenolysis of diisobutene: [2]

α,ω-Dienes, i.e., diolefins of the formula (CH2)n(CH=CH2)2, are prepared industrially by ethenolysis of cyclic alkenes. For example, 1,5-hexadiene, a useful crosslinking agent and synthetic intermediate, is produced from 1,5-cyclooctadiene:

The catalyst is derived from rhenium(VII) oxide supported on alumina. [2] 1,9-Decadiene, a related species, is produced similarly from cyclooctene.

Decenoic acid

In an application directed at using renewable feedstocks, [3] methyl oleate, derived from natural seed oils, can be converted to 1-decene and methyl 9-decenoate: [4] [5]

Polyethylene and polypropylene recycling

Mixed polyolefins can be recycled via high selectivity isomerizing ethenolysation using a sodium on alumina catalyst followed by olefin metathesis using a stream of ethylene gas flowing into a reaction chamber containing a tungsten oxide on silica catalyst, albeit at high temperature. Carbon atoms freed by the breaking carbon-carbon bonds attach to ethylene molecules. Polyethylene is first converted to propylene, while polypropylene is ultimately converted to a mixture of propylene and isobutylene. [6]

Related Research Articles

<span class="mw-page-title-main">Alkene</span> Hydrocarbon compound containing one or more C=C bonds

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.

<span class="mw-page-title-main">Alkyne</span> Hydrocarbon compound containing one or more C≡C bonds

In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula CnH2n−2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature. Like other hydrocarbons, alkynes are generally hydrophobic.

<span class="mw-page-title-main">Ethylene oxide</span> Cyclic compound (C2H4O)

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.

<span class="mw-page-title-main">Epoxide</span> Organic compounds with a carbon-carbon-oxygen ring

In organic chemistry, an epoxide is a cyclic ether, where the ether forms a three-atom ring: two atoms of carbon and one atom of oxygen. This triangular structure has substantial ring strain, making epoxides highly reactive, more so than other ethers. They are produced on a large scale for many applications. In general, low molecular weight epoxides are colourless and nonpolar, and often volatile.

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.

<span class="mw-page-title-main">Isobutylene</span> Unsaturated hydrocarbon compound (H2C=C(CH3)2)

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, a rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another atom in the same molecule, hence these reactions are usually intramolecular. In the example below, the substituent R moves from carbon atom 1 to carbon atom 2:

<span class="mw-page-title-main">Olefin metathesis</span> Organic reaction involving the breakup and reassembly of alkene double bonds

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.

<span class="mw-page-title-main">Terminal alkene</span> Hydrocarbon compounds with a C=C bond at the alpha carbon

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.

The Shell higher olefin process (SHOP) is a chemical process for the production of linear alpha olefins via ethylene oligomerization and olefin metathesis invented and exploited by Royal Dutch Shell. The olefin products are converted to fatty aldehydes and then to fatty alcohols, which are precursors to plasticizers and detergents. The annual global production of olefins through this method is over one million tonnes.

In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications.

In chemistry, carbonylation refers to reactions that introduce carbon monoxide (CO) into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbonylation also refers to oxidation of protein side chains.

Decene is an organic compound with the chemical formula C10H20. Decene contains a chain of ten carbon atoms with one double bond, making it an alkene. There are many isomers of decene depending on the position and geometry of the double bond. Dec-1-ene is the only isomer of industrial importance. As an alpha olefin, it is used as a comonomer in copolymers and is an intermediate in the production of epoxides, amines, oxo alcohols, synthetic lubricants, synthetic fatty acids and alkylated aromatics.

<span class="mw-page-title-main">Metallacycle</span>

In organometallic chemistry, a metallacycle is a derivative of a carbocyclic compound wherein a metal has replaced at least one carbon center; this is to some extent similar to heterocycles. Metallacycles appear frequently as reactive intermediates in catalysis, e.g. olefin metathesis and alkyne trimerization. In organic synthesis, directed ortho metalation is widely used for the functionalization of arene rings via C-H activation. One main effect that metallic atom substitution on a cyclic carbon compound is distorting the geometry due to the large size of typical metals.

<span class="mw-page-title-main">Organorhodium chemistry</span> Field of study

Organorhodium chemistry is the chemistry of organometallic compounds containing a rhodium-carbon chemical bond, and the study of rhodium and rhodium compounds as catalysts in organic reactions.

An insertion reaction is a chemical reaction where one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.:

<span class="mw-page-title-main">Neohexene</span> Hydrocarbon compound ((CH3)3CCH=CH2)

Neohexene is the hydrocarbon compound with the chemical formula (CH3)3CCH=CH2. It is a colorless liquid, with properties similar to other hexenes. It is a precursor to commercial synthetic musk perfumes.

In organic chemistry, hydrovinylation is the formal insertion of an alkene into the C-H bond of ethylene :

Olefin Conversion Technology, also called the Phillips Triolefin Process, is the industrial process that interconverts propylene with ethylene and 2-butenes. The process is also called the ethylene to propylene (ETP) process. In ETP, ethylene is dimerized to 1-butene, which is isomerized to 2-butenes. The 2-butenes are then subjected to metathesis with ethylene.

In organic chemistry, methylenation is a chemical reaction that inserts a methylene group into a chemical compound:

References

  1. ↑ K. Weissermel, H. J. Arpe: Industrial Organic Chemistry: Important Raw Materials and Intermediates. Wiley-VCH Verlag 2003, ISBN   3-527-30578-5
  2. 1 2 Lionel Delaude; Alfred F. Noels (2005). "Metathesis". Kirk-Othmer Encyclopedia of Chemical Technology. Weinheim: Wiley-VCH. doi:10.1002/0471238961.metanoel.a01. ISBN   0-471-23896-1.
  3. ↑ Metzger, J. O.; Bornscheuer, U. (2006). "Lipids as renewable resources: current state of chemical and biotechnological conversion and diversification". Applied Microbiology and Biotechnology. 71 (1): 13–22. doi:10.1007/s00253-006-0335-4. PMID   16604360. S2CID   28601501.
  4. ↑ Marinescu, Smaranda C.; Schrock, Richard R.; Müller, Peter; Hoveyda, Amir H. (2009). "Ethenolysis Reactions Catalyzed by Imido Alkylidene Monoaryloxide Monopyrrolide (MAP) Complexes of Molybdenum". J. Am. Chem. Soc. 131 (31): 10840–10841. doi:10.1021/ja904786y. PMID   19618951.
  5. ↑ Schrodi, Yann; Ung, Thay; Vargas, Angel; Mkrtumyan, Garik; Lee, Choon Woo; Champagne, Timothy M.; Pederson, Richard L.; Hong, Soon Hyeok (2008). "Ruthenium Olefin Metathesis Catalysts for the Ethenolysis of Renewable Feedstocks". CLEAN - Soil, Air, Water. 36 (8): 669–673. Bibcode:2008CSAW...36..669S. doi:10.1002/clen.200800088.
  6. ↑ Technica, Elizabeth Rayne, Ars (September 27, 2024). "Scientists Figured Out How to Recycle Plastic by Vaporizing It". Wired. ISSN   1059-1028 . Retrieved 2024-10-05.{{cite news}}: CS1 maint: multiple names: authors list (link)
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.