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{{DISPLAYTITLE:''trans''-Cyclooctene}}
{{DISPLAYTITLE:''trans''-Cyclooctene}}
{{chembox
{{chembox
| Reference =<ref>{{cite web |url= http://www.sigmaaldrich.com/catalog/search/ProductDetail/ALDRICH/125482 |title= ''cis''-Cyclooctene |publisher= [[Sigma-Aldrich]] }}</ref>
|Reference =<ref>{{cite web |url= http://www.sigmaaldrich.com/catalog/search/ProductDetail/ALDRICH/125482 |title= ''cis''-Cyclooctene |publisher= [[Sigma-Aldrich]] }}</ref>
| Name =''trans''-Cyclooctene
|Name =''trans''-Cyclooctene
| ImageFile =Trans-coe.png
|ImageFile =Trans-Cyclooctene.png
| ImageSize = 344 px
|ImageSize = 344 px
| IUPACName =(''E'')-Cyclooctene
|PIN =(''E'')-Cyclooctene
| OtherNames =''trans''-Cyclooctene
|OtherNames =''trans''-Cyclooctene
|Section1={{Chembox Identifiers
|Section1={{Chembox Identifiers
| ChemSpiderID = 10265272
|ChemSpiderID = 10265272
| InChI=1S/C8H14/c1-2-4-6-8-7-5-3-1/h1-2H,3-8H2/b2-1+
|InChI=1S/C8H14/c1-2-4-6-8-7-5-3-1/h1-2H,3-8H2/b2-1+
| InChIKey = URYYVOIYTNXXBN-OWOJBTEDSA-N
|InChIKey = URYYVOIYTNXXBN-OWOJBTEDSA-N
| CASNo =931-89-5
|CASNo =931-89-5
| PubChem =5463599
|PubChem =5463599
|ChEBI = 73156
⚫
| SMILES = C1CCC/C=C/CC1
|EINECS = 213-245-5
⚫
|SMILES = C1CCC/C=C/CC1
}}
}}
|Section2={{Chembox Properties
|Section2={{Chembox Properties
| C=8 | H=14
|C=8 | H=14
| Appearance =
|Appearance = colorless liquid
| Density =0.848 g/mL
|Density =0.848 g/mL
| MeltingPtC = -59
|MeltingPtC = -59
|BoilingPt = 143 °C (1 atm); 68-72 °C (100 torr)<ref name=vede1973/>
| BoilingPtC = 143
⚫
}}
| BoilingPt_notes =
| Solubility =
}}
|Section3={{Chembox Hazards
|Section3={{Chembox Hazards
|GHSPictograms = {{GHS02}}{{GHS08}}
| MainHazards =
|GHSSignalWord = Danger
| FlashPt =
⚫
}}
| AutoignitionPt =
⚫
}}
}}
}}


'''''trans''-Cyclooctene''' is a [[cyclic compound|cyclic]] [[hydrocarbon]] with the formula [–(CH<sub>2</sub>)<sub>6</sub>CH=CH–], where the two C–C single bonds adjacent to the double bond are on opposite sides of the latter's plane. It is a colorless liquid with a disagreeable odor.
'''''trans''-Cyclooctene''' is a [[cycloalkene]] with an eight-membered ring. It is notable as the smallest cycloalkene that exist as a ''trans''-[[isomer]]. The ''cis''-isomer is much more stable.<ref name="cis">{{cite journal |first1= Ulrich |last1= Neuenschwander |first2= Ive |last2= Hermans |doi= 10.1021/jo202176j |title= The Conformations of Cyclooctene: Consequences for Epoxidation Chemistry |journal= [[J. Org. Chem.]] |volume= 76 |issue= 24 |pages= 10236–10240 |year= 2011 }}</ref> It is a colorless liquid.


[[Cyclooctene]] is notable as the smallest cycloalkene that is readily isolated as its ''trans''-[[isomer]]. The ''cis''-isomer is much more stable;<ref name=neue2011>{{cite journal |first1= Ulrich |last1= Neuenschwander |first2= Ive |last2= Hermans |doi= 10.1021/jo202176j |title= The conformations of cyclooctene: Consequences for epoxidation chemistry |journal=[[Journal of Organic Chemistry]]|volume= 76 |issue= 24 |pages= 10236–10240 |year= 2011 |pmid= 22077196 }}</ref> the ring-strain energies being 16.7 and 7.4 kcal/mol, respectively.<ref name=walk2009>{{cite journal | doi=10.1021/ma801693q | title=The Living ROMP of ''trans''-Cyclooctene | year=2009 | last1=Walker | first1=Ron | last2=Conrad | first2=Rosemary M. | last3=Grubbs | first3=Robert H. | journal=[[Macromolecules (journal)|Macromolecules]] | volume=42 | issue=3 | pages=599–605 | pmid=20379393 | pmc=2850575 | bibcode=2009MaMol..42..599W}}</ref>
{| class="wikitable"

⚫
| [[Image:Cis-cyclooctene3D.png|150px]] || align="right"|[[Image:Trans-cyclooctene3D.png|150px]]   
{| style="margin-left:auto;margin-right:auto;"
⚫
| [[File:Cis-cyclooctene 3D chair conformation.png|150px]] || align="right"|[[Image:Trans-cyclooctene Rp 3D crown conformation.png|150px]]
|- align="center"
|- align="center"
| ''cis''-Cyclooctene      ||     ''trans''-Cyclooctene   
| [[cis-Cyclooctene|''cis''-Cyclooctene]]<br />in ''chair'' conformation ||(''R<sub>p</sub>'')-''trans''-Cyclooctene<br />in ''crown'' conformation
|}
|}
{{clear-left}}
{{clear-left}}


A planar arrangement of the ring carbons would be too strained, and therefore the stable [[conformational isomer|conformations]] of the ''trans'' form have a bent (non-planar) ring. Computations indicate that the most stable "crown" conformation has the carbon atoms alternately above and below the plane of the ring.<ref name=selv2013/> A "half-chair" conformation, with about 6 kcal/mol higher energy, has carbons 2,3,5,6, and 8 on the same side of the plane of carbons 1,4, and 7.<ref name=selv2013/>
''trans''-Cyclooctene is the smallest cycloalkene in which the ''trans''-isomer is stable at room temperature. The molecule is shaped like the 8-carbon equivalent chair conformation of cyclohexane. It is [[chirality|chiral]] (the two enantiomers are shown in the table above). This type of chirality is defined as [[planar chirality#In chemistry|planar chirality]].<ref>{{GoldBookRef |file= P04681 |title= Planar chirality}}</ref> It has been resolved into optical isomers.<ref>{{cite encyclopedia|title=(−)-Dichloro(ethylene)(α-methylbenzylamine)platinum(II)|authors=Steven D. Paget|encyclopedia= Encyclopedia of Reagents for Organic Synthesis|year=2001|publisher= John Wiley & Sons|doi=10.1002/047084289X.rd119}}</ref>

All conformations of ''trans''-cyclooctene are [[chirality|chiral]] (specifically, what some call [[planar chirality#In chemistry|planar-chiral]]<ref>{{GoldBookRef |file= P04681 |title= Planar chirality}}</ref>) and the [[enantiomer]]s can be separated.<ref name=cope1963>{{cite journal | doi=10.1021/ja00903a049 | title=Molecular Asymmetry of Olefins. I. Resolution of ''trans''-Cyclooctene<sup>1-3</sup> | year=1963 | last1=Cope | first1=Arthur C. | last2=Ganellin | first2=C. R. | last3=Johnson | first3=H. W. | last4=Van Auken | first4=T. V. | last5=Winkler | first5=Hans J. S. | journal=[[Journal of the American Chemical Society]] | volume=85 | issue=20 | pages=3276–3279 }}</ref><ref name=cope1964>{{cite journal | doi=10.1021/ja01078a044 | title=Molecular Asymmetry of Olefins. II. The Absolute Configuration of ''trans''-Cyclooctene | year=1964 | last1=Cope | first1=Arthur C. | last2=Mehta | first2=Anil S. | journal=[[Journal of the American Chemical Society]] | volume=86 | issue=24 | pages=5626–5630 }}</ref><ref>{{cite encyclopedia|title=(−)-Dichloro(ethylene)(α-methylbenzylamine)platinum(II)|author=Steven D. Paget |encyclopedia= Encyclopedia of Reagents for Organic Synthesis|year=2001|publisher= John Wiley & Sons|doi=10.1002/047084289X.rd119|isbn=0-471-93623-5 }}</ref> In theory, conversion of between the enantiomers can be done, without breaking any bonds, by twisting the whole –CH=CH– group, rigidly, by 180 degrees. However, that entails passing one of its hydrogens through the crowded ring.<ref name=cope1963/>


==Preparation==
==Preparation==
''trans''-Cyclooctene was first synthesized on a preparatory scale by [[Arthur C. Cope]] with a [[Hofmann elimination]] reaction of ''N,N,N''-trimethylcyclooctylammonium iodide.<ref>{{OrgSynth |first1= Arthur C. |last1= Cope |author1-link= Arthur C. Cope |first2= Robert D. |last2= Bach |year=1969 |title=''trans''-Cyclooctene |volume=49 |pages=39 |collvol=5 |collvolpages=315 |prep=CV5P0315}}</ref> The reaction gives a mixture of ''cis'' and ''trans'' isomers, and the ''trans'' isomer is selectively [[chemical trap|trapped]] as a [[Coordination complex|complex]] with [[silver nitrate]]. Other methods exist where the ''trans''-isomer is synthesized from the ''cis''-isomer in several synthetic steps. In addition, a [[photochemical]] method exists for the direct ''cis''–''trans'' isomerisation.
''trans''-Cyclooctene was first synthesized on a preparatory scale by [[Arthur C. Cope]] with a [[Hofmann elimination]] reaction of ''N,N,N''-trimethylcyclooctylammonium iodide.<ref name=cope1969>{{OrgSynth |first1= Arthur C. |last1= Cope |author1-link= Arthur C. Cope |first2= Robert D. |last2= Bach |year=1969 |title=''trans''-Cyclooctene |volume=49 |pages=39 |collvol=5 |collvolpages=315 |prep=CV5P0315}}</ref> The reaction gives a mixture of ''cis'' and ''trans'' isomers, and the ''trans'' isomer is selectively [[chemical trap|trapped]] as a [[Coordination complex|complex]] with [[silver nitrate]].

Other methods exist where the ''trans'' isomer is synthesized from the ''cis'' isomer in several synthetic steps. For instance, it can be prepared in almost 100% yield by converting the ''cis'' isomer to [[1,2-epoxycyclooctane]] ("cyclooctene oxide") followed by reactions with [[lithium diphenylphosphide]] ({{chem|LiPPh|2}}) and with [[methyl iodide]] {{chem|CH|3|I}}. (Similar procedures can give ''{{chem name|cis'',''trans}}'' isomers of [[1,4-cyclooctadiene]]<!-- MP 208-209° --> and [[1,5-cyclooctadiene]]<!-- MP (mp 178-179°-->).<ref name=vede1973>{{cite journal | doi=10.1021/jo00946a024 | title=Phosphorus betaines derived from cycloheptene and cyclooctene oxides. Inversion of cyclooctene | year=1973 | last1=Vedejs | first1=Edwin | last2=Snoble | first2=Karel A. J. | last3=Fuchs | first3=Philip L. | journal=[[Journal of Organic Chemistry]] | volume=38 | issue=6 | pages=1178–1183 }}</ref>

⚫
In addition, a [[photochemical]] method exists for the direct ''cis''–''trans'' isomerisation. Although this equilibrium strongly favours the more stable ''cis'' form, the reaction can be driven towards the ''trans'' form by trapping with silver ions.<ref name=swen1969>{{cite journal | doi=10.1021/jo01262a102 | title=Photoisomerization of ''cis''-cyclooctene to ''trans''-cyclooctene | year=1969 | last1=Swenton | first1=John S. | journal=[[Journal of Organic Chemistry]] | volume=34 | issue=10 | pages=3217–3218 }}</ref><ref name=royz2008>{{cite journal |title= A photochemical synthesis of functionalized ''trans''-cyclooctenes driven by metal complexation |first1= Maksim |last1= Royzen |first2= Glenn P. A. |last2= Yap |first3= Joseph M. |last3= Fox |journal= [[Journal of the American Chemical Society]]|year= 2008 |volume= 130 |issue= 12 |pages= 3760–3761 |doi= 10.1021/ja8001919 |pmid= 18321114 }}</ref>


==Reactions==
⚫
Although this equilibrium strongly favours the more stable ''cis'' form, the reaction can be driven towards the ''trans'' by trapping with silver ions.<ref>{{cite journal |title= A Photochemical Synthesis of Functionalized ''trans''-Cyclooctenes Driven by Metal Complexation |first1= Maksim |last1= Royzen |first2= Glenn P. A. |last2= Yap |first3= Joseph M. |last3= Fox |journal= [[J. Am. Chem. Soc.]] |year= 2008 |volume= 130 |issue= 12 |pages= 3760–3761 |doi= 10.1021/ja8001919 }}</ref>
Because of the higher internal strain on the double bond, the ''trans'' isomer is more reactive than the ''cis'' isomer and of typical unsaturated hydrocarbons. For instance, its double bond will rapidly [[addition reaction|add]] [[tetrazine]] and its derivatives.<ref name=selv2013>{{cite journal | doi=10.1016/j.cbpa.2013.07.031 | title=''trans''-Cyclooctene — A stable, voracious dienophile for bioorthogonal labeling | year=2013 | last1=Selvaraj | first1=Ramajeyam | last2=Fox | first2=Joseph M. | journal=[[Current Opinion in Chemical Biology]] | volume=17 | issue=5 | pages=753–760 | pmid=23978373 | pmc=3925366 }}</ref> The compound also readily polymerizes with a [[ruthenium]]-based initiator.<ref name=walk2009/>


==References==
==References==
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{{Authority control}}
{{Authority control}}
[[Category:Cycloalkenes]]
[[Category:Cycloalkenes]]
[[Category:Foul-smelling chemicals]]

Latest revision as of 17:29, 30 September 2023

trans-Cyclooctene[1]
Names
Preferred IUPAC name
(E)-Cyclooctene
Other names
trans-Cyclooctene
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
EC Number
  • 213-245-5
  • InChI=1S/C8H14/c1-2-4-6-8-7-5-3-1/h1-2H,3-8H2/b2-1+
    Key: URYYVOIYTNXXBN-OWOJBTEDSA-N
  • C1CCC/C=C/CC1
Properties
C8H14
Molar mass 110.200 g·mol−1
Appearance colorless liquid
Density 0.848 g/mL
Melting point −59 °C (−74 °F; 214 K)
Boiling point 143 °C (1 atm); 68-72 °C (100 torr)[2]
Hazards
GHS labelling:
GHS02: FlammableGHS08: Health hazard
Danger
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

trans-Cyclooctene is a cyclic hydrocarbon with the formula [–(CH2)6CH=CH–], where the two C–C single bonds adjacent to the double bond are on opposite sides of the latter's plane. It is a colorless liquid with a disagreeable odor.

Cyclooctene is notable as the smallest cycloalkene that is readily isolated as its trans-isomer. The cis-isomer is much more stable;[3] the ring-strain energies being 16.7 and 7.4 kcal/mol, respectively.[4]

cis-Cyclooctene
in chair conformation		 (Rp)-trans-Cyclooctene
in crown conformation

A planar arrangement of the ring carbons would be too strained, and therefore the stable conformations of the trans form have a bent (non-planar) ring. Computations indicate that the most stable "crown" conformation has the carbon atoms alternately above and below the plane of the ring.[5] A "half-chair" conformation, with about 6 kcal/mol higher energy, has carbons 2,3,5,6, and 8 on the same side of the plane of carbons 1,4, and 7.[5]

All conformations of trans-cyclooctene are chiral (specifically, what some call planar-chiral[6]) and the enantiomers can be separated.[7][8][9] In theory, conversion of between the enantiomers can be done, without breaking any bonds, by twisting the whole –CH=CH– group, rigidly, by 180 degrees. However, that entails passing one of its hydrogens through the crowded ring.[7]

Preparation

[edit]

trans-Cyclooctene was first synthesized on a preparatory scale by Arthur C. Cope with a Hofmann elimination reaction of N,N,N-trimethylcyclooctylammonium iodide.[10] The reaction gives a mixture of cis and trans isomers, and the trans isomer is selectively trapped as a complex with silver nitrate.

Other methods exist where the trans isomer is synthesized from the cis isomer in several synthetic steps. For instance, it can be prepared in almost 100% yield by converting the cis isomer to 1,2-epoxycyclooctane ("cyclooctene oxide") followed by reactions with lithium diphenylphosphide (LiPPh
2) and with methyl iodide CH
3I. (Similar procedures can give cis,trans isomers of 1,4-cyclooctadiene and 1,5-cyclooctadiene).[2]

In addition, a photochemical method exists for the direct cis–trans isomerisation. Although this equilibrium strongly favours the more stable cis form, the reaction can be driven towards the trans form by trapping with silver ions.[11][12]

Reactions

[edit]

Because of the higher internal strain on the double bond, the trans isomer is more reactive than the cis isomer and of typical unsaturated hydrocarbons. For instance, its double bond will rapidly add tetrazine and its derivatives.[5] The compound also readily polymerizes with a ruthenium-based initiator.[4]

References

[edit]
  1. ^ "cis-Cyclooctene". Sigma-Aldrich.
  2. ^ a b Vedejs, Edwin; Snoble, Karel A. J.; Fuchs, Philip L. (1973). "Phosphorus betaines derived from cycloheptene and cyclooctene oxides. Inversion of cyclooctene". Journal of Organic Chemistry. 38 (6): 1178–1183. doi:10.1021/jo00946a024.
  3. ^ Neuenschwander, Ulrich; Hermans, Ive (2011). "The conformations of cyclooctene: Consequences for epoxidation chemistry". Journal of Organic Chemistry. 76 (24): 10236–10240. doi:10.1021/jo202176j. PMID 22077196.
  4. ^ a b Walker, Ron; Conrad, Rosemary M.; Grubbs, Robert H. (2009). "The Living ROMP of trans-Cyclooctene". Macromolecules. 42 (3): 599–605. Bibcode:2009MaMol..42..599W. doi:10.1021/ma801693q. PMC 2850575. PMID 20379393.
  5. ^ a b c Selvaraj, Ramajeyam; Fox, Joseph M. (2013). "trans-Cyclooctene — A stable, voracious dienophile for bioorthogonal labeling". Current Opinion in Chemical Biology. 17 (5): 753–760. doi:10.1016/j.cbpa.2013.07.031. PMC 3925366. PMID 23978373.
  6. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Planar chirality". doi:10.1351/goldbook.P04681
  7. ^ a b Cope, Arthur C.; Ganellin, C. R.; Johnson, H. W.; Van Auken, T. V.; Winkler, Hans J. S. (1963). "Molecular Asymmetry of Olefins. I. Resolution of trans-Cyclooctene1-3". Journal of the American Chemical Society. 85 (20): 3276–3279. doi:10.1021/ja00903a049.
  8. ^ Cope, Arthur C.; Mehta, Anil S. (1964). "Molecular Asymmetry of Olefins. II. The Absolute Configuration of trans-Cyclooctene". Journal of the American Chemical Society. 86 (24): 5626–5630. doi:10.1021/ja01078a044.
  9. ^ Steven D. Paget (2001). "(−)-Dichloro(ethylene)(α-methylbenzylamine)platinum(II)". Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. doi:10.1002/047084289X.rd119. ISBN 0-471-93623-5.
  10. ^ Cope, Arthur C.; Bach, Robert D. (1969). "trans-Cyclooctene". Organic Syntheses. 49: 39; Collected Volumes, vol. 5, p. 315.
  11. ^ Swenton, John S. (1969). "Photoisomerization of cis-cyclooctene to trans-cyclooctene". Journal of Organic Chemistry. 34 (10): 3217–3218. doi:10.1021/jo01262a102.
  12. ^ Royzen, Maksim; Yap, Glenn P. A.; Fox, Joseph M. (2008). "A photochemical synthesis of functionalized trans-cyclooctenes driven by metal complexation". Journal of the American Chemical Society. 130 (12): 3760–3761. doi:10.1021/ja8001919. PMID 18321114.
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