Oligomer: Difference between revisions
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[[File:15-crown-5 and monomer 3D balls.png|thumb|right|The [[15-crown-5]] [[crown ether]], a cyclic oligomer, and its monomer, [[ethylene oxide]].]] |
[[File:15-crown-5 and monomer 3D balls.png|thumb|right|The [[15-crown-5]] [[crown ether]], a cyclic oligomer, and its monomer, [[ethylene oxide]].]] |
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In [[chemistry]] and [[biochemistry]], an '''oligomer''' ({{IPAc-en|audio=En-us-Oligomer.oga|ə|ˈ|l|ɪ|g|ə|m|ər}} is [[molecule]] that consists of a few similar or identical [[repeating unit]]s |
In [[chemistry]] and [[biochemistry]], an '''oligomer''' ({{IPAc-en|audio=En-us-Oligomer.oga|ə|ˈ|l|ɪ|g|ə|m|ər}} is [[molecule]] that consists of a few similar or identical [[repeating unit]]s which could be derived, actually or conceptually, from copies of a smaller molecule, its [[monomer]]. <ref name=webster>{{cite web|title=Oligomer|url=http://www.merriam-webster.com/dictionary/oligomer|publisher=[[Merriam-Webster]]|accessdate=25 October 2014}}</ref> <ref name=Goldbook-Oligomer>{{GoldBookRef |title=oligomer molecule |file=O04286 }}</ref><ref name=IUPAC1966>{{cite journal|title=Glossary of basic terms in polymer science (IUPAC Recommendations 1996)|journal=[[Pure and Applied Chemistry]]|year=1996|volume=68|issue=12|pages=2287–2311|doi=10.1351/pac199668122287|last1=Jenkins|first1=A. D.|last2=Kratochvíl|first2=P.|last3=Stepto|first3=R. F. T.|last4=Suter|first4=U. W.|doi-access=free}}Quote: ''Oligomer molecule: A molecule of intermediate relative molecular mass, the structure of which essentially comprises a small plurality of units derived, actually or conceptually, from molecules of lower relative molecular mass.''</ref> The name is composed from [[Greek language|Greek]] elements ''[[wikt:oligo-|oligo-]]'', "a few" and ''[[wikt:-mer|-mer]]'', "parts". An [[adjective]] form is '''oligomeric'''.<ref name=IUPAC1966/> |
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The oligomer concept contrasted to that of a [[polymer]] which is usually understood to have a large number of units, possibly thousands or millions. |
The oligomer concept contrasted to that of a [[polymer]] which is usually understood to have a large number of units, possibly thousands or millions. However, there is no sharp distinction between these two concepts. One proposed criterion is whether the molecule's properties vary significantly with the removal of one or a few of the units.<ref name=IUPAC1966/> |
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An oligomer with a specific number of units is referred to by the Greek prefix denoting that number with the ending ''-mer'': thus [[dimer (chemistry)|dimer]], [[trimer (chemistry)|trimer]], [[tetramer]], [[pentamer]] refer to molecules with two, three, four, and five |
An oligomer with a specific number of units is referred to by the Greek prefix denoting that number with the ending ''-mer'': thus [[dimer (chemistry)|dimer]], [[trimer (chemistry)|trimer]], [[tetramer]], [[pentamer]] refer to molecules with two, three, four, and five units, respectively. The units of an oligomer may be arranged in a linear chain (as in [[melam]], a dimer of [[melamine]]), a closed ring (as in [[trioxane]], a cyclic trimer of [[formaldehyde]]), or more complex structure (as in [[tellurium tetrabromide]], a tetramer of {{chem2|TiBr4}} with a [[cube]]-like core). If the units are identical, one has a '''homo-oligomer'''; otherwise one may use '''hetero-oligomer'''. An example of a homo-oligomeric protein is [[collagen]], which is composed of three identical protein chains. |
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[[File:Tetrapeptide structural formulae v.1.png|thumb|right|A [[tetrapeptide]], a hetero-oligomer of the amino acids [[valine]] (green), [[glycine]] (black), [[serine]] (black), and [[alanine]] (blue). The units were joined by condensation of the [[carboxylic acid]] group –C(=O)OH of one monomer with the [[amine group]] {{chem2|H2N\s}} of the next one.]] |
[[File:Tetrapeptide structural formulae v.1.png|thumb|right|A [[tetrapeptide]], a hetero-oligomer of the amino acids [[valine]] (green), [[glycine]] (black), [[serine]] (black), and [[alanine]] (blue). The units were joined by condensation of the [[carboxylic acid]] group –C(=O)OH of one monomer with the [[amine group]] {{chem2|H2N\s}} of the next one.]] |
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[[File:Mpyv vp1 pentamer vp2 1sie 1cn3.png|thumb|right|A pentamer unit of the major capsid protein VP1. Each monomer is in a different color.]] |
[[File:Mpyv vp1 pentamer vp2 1sie 1cn3.png|thumb|right|A pentamer unit of the major capsid protein VP1. Each monomer is in a different color.]] |
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The units of an oligomer may be connected by [[covalent bond]]s, or by weaker forces such as [[hydrogen bond]]s. The term '''multimer''' ({{IPAc-en|ˈ|m|ʌ|l|t|ᵻ|m|ər}}) is used in biochemistry for oligomers of proteins that are not covalently bound. The [[major capsid protein VP1]] that comprises the shell of the [[polyomavirus|polio virus]] is a aelf-assembling multimer of 72 pentamers held together by local electric charges. |
The units of an oligomer may be connected by [[covalent bond]]s, which may result from bond rearrangement or [[condensation reaction]]s, or by weaker forces such as [[hydrogen bond]]s. The term '''multimer''' ({{IPAc-en|ˈ|m|ʌ|l|t|ᵻ|m|ər}}) is used in biochemistry for oligomers of proteins that are not covalently bound. The [[major capsid protein VP1]] that comprises the shell of the [[polyomavirus|polio virus]] is a aelf-assembling multimer of 72 pentamers held together by local electric charges. |
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Many [[oil]]s are oligomeric, such as [[Liquid paraffin (medicinal)|liquid paraffin]]. [[Plasticizers]] are oligomeric [[ester]]s widely used to soften [[thermoplastics]] such as [[polyvinyl chloride|PVC]]. They may be made from [[monomer]]s by linking them together, or by separation from the higher fractions of [[crude oil]]. [[Polybutene]] is an oligomeric oil used to make [[putty]]. |
Many [[oil]]s are oligomeric, such as [[Liquid paraffin (medicinal)|liquid paraffin]]. [[Plasticizers]] are oligomeric [[ester]]s widely used to soften [[thermoplastics]] such as [[polyvinyl chloride|PVC]]. They may be made from [[monomer]]s by linking them together, or by separation from the higher fractions of [[crude oil]]. [[Polybutene]] is an oligomeric oil used to make [[putty]]. |
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'''Oligomerization''' is a chemical process that converts monomers to macromolecular complexes through a finite [[degree of polymerization]]. <ref name=IUPAC1966/> |
'''Oligomerization''' is a chemical process that converts monomers to macromolecular complexes through a finite [[degree of polymerization]]. <ref name=IUPAC1966/> '''[[Telomerization]]''' is an oligomerization carried out under conditions that result in [[chain transfer]], limiting the size of the oligomers.<ref name=Goldbook-Telomerization>{{GoldBookRef |title=telomerization |file=T06260 }}</ref><ref name=IUPAC1966 /> (This concept is not to be confused with the formation of a [[telomere]], a region of highly repetitive DNA at the end of a [[chromosome]].) |
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'''[[Telomerization]]''' is an oligomerization carried out under conditions that result in [[chain transfer]], limiting the size of the oligomers.<ref name=Goldbook-Telomerization>{{GoldBookRef |title=telomerization |file=T06260 }}</ref><ref name=IUPAC1966 /> (This concept is not to be confused with the formation of a [[telomere]], a region of highly repetitive DNA at the end of a [[chromosome]].) |
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==Green oil== |
==Green oil== |
Revision as of 08:31, 11 July 2020
In chemistry and biochemistry, an oligomer (/əˈlɪɡəmər/ is molecule that consists of a few similar or identical repeating units which could be derived, actually or conceptually, from copies of a smaller molecule, its monomer. [1] [2][3] The name is composed from Greek elements oligo-, "a few" and -mer, "parts". An adjective form is oligomeric.[3]
The oligomer concept contrasted to that of a polymer which is usually understood to have a large number of units, possibly thousands or millions. However, there is no sharp distinction between these two concepts. One proposed criterion is whether the molecule's properties vary significantly with the removal of one or a few of the units.[3]
An oligomer with a specific number of units is referred to by the Greek prefix denoting that number with the ending -mer: thus dimer, trimer, tetramer, pentamer refer to molecules with two, three, four, and five units, respectively. The units of an oligomer may be arranged in a linear chain (as in melam, a dimer of melamine), a closed ring (as in trioxane, a cyclic trimer of formaldehyde), or more complex structure (as in tellurium tetrabromide, a tetramer of TiBr4 with a cube-like core). If the units are identical, one has a homo-oligomer; otherwise one may use hetero-oligomer. An example of a homo-oligomeric protein is collagen, which is composed of three identical protein chains.
Some biologically important oligomers consist of macromolecules like proteins or nucleic acids; for instance, hemoglobin is a protein tetramer. An oligomer of amino acids is called an oligopeptide or just a peptide. An oligosaccharide is an oligomer of monosaccharides (simple sugars). An oligonucleotide is a short single-stranded fragment of nucleic acid such as DNA or RNA, or similar fragments of analogs of nucleic acids such as peptide nucleic acid or Morpholinos.
The units of an oligomer may be connected by covalent bonds, which may result from bond rearrangement or condensation reactions, or by weaker forces such as hydrogen bonds. The term multimer (/ˈmʌltɪmər/) is used in biochemistry for oligomers of proteins that are not covalently bound. The major capsid protein VP1 that comprises the shell of the polio virus is a aelf-assembling multimer of 72 pentamers held together by local electric charges.
Many oils are oligomeric, such as liquid paraffin. Plasticizers are oligomeric esters widely used to soften thermoplastics such as PVC. They may be made from monomers by linking them together, or by separation from the higher fractions of crude oil. Polybutene is an oligomeric oil used to make putty.
Oligomerization is a chemical process that converts monomers to macromolecular complexes through a finite degree of polymerization. [3] Telomerization is an oligomerization carried out under conditions that result in chain transfer, limiting the size of the oligomers.[4][3] (This concept is not to be confused with the formation of a telomere, a region of highly repetitive DNA at the end of a chromosome.)
Green oil
In the oil and gas industry, green oil refers to oligomers formed in all C2, C3, and C4 hydrogenation reactors of ethylene plants and other petrochemical production facilities; it is a mixture of C4 to C20 unsaturated and reactive components with about 90% aliphatic dienes and 10% of alkanes plus alkenes.[5] Different heterogeneous and homogeneous catalysts are operative in producing green oils via the oligomerization of alkenes[6]
See also
References
- ^ "Oligomer". Merriam-Webster. Retrieved 25 October 2014.
- ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "oligomer molecule". doi:10.1351/goldbook.O04286
- ^ a b c d e Jenkins, A. D.; Kratochvíl, P.; Stepto, R. F. T.; Suter, U. W. (1996). "Glossary of basic terms in polymer science (IUPAC Recommendations 1996)". Pure and Applied Chemistry. 68 (12): 2287–2311. doi:10.1351/pac199668122287.Quote: Oligomer molecule: A molecule of intermediate relative molecular mass, the structure of which essentially comprises a small plurality of units derived, actually or conceptually, from molecules of lower relative molecular mass.
- ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "telomerization". doi:10.1351/goldbook.T06260
- ^ "Chemicals & Polymers". www.pall.com.
- ^ Ghashghaee, Mohammad (2018). "Heterogeneous catalysts for gas-phase conversion of ethylene to higher olefins". Rev. Chem. Eng. 34 (5): 595–655. doi:10.1515/revce-2017-0003.
External links
Media related to Oligomers at Wikimedia Commons