Cyclohexyne

Last updated
Cyclohexyne
Cyclohexyne.svg
Names
Preferred IUPAC name
Cyclohexyne
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
  • InChI=1S/C6H8/c1-2-4-6-5-3-1/h1-4H2
    Key: AAFFTDXPYADISO-UHFFFAOYSA-N
  • C1CCC#CC1
Properties
C6H8
Molar mass 80.130 g·mol−1
Density 0.9 g/cm³
Boiling point 100.1
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Cyclohexyne is a highly reactive, strained cyclic alkyne with the molecular formula C6H8 and the structure of a six-membered carbon ring containing a triple bond. [1] It is a member of the class of compounds known as arynes (or more broadly, cycloalkynes ) and is best classified as a six-membered cyclic alkyne . Due to its high ring strain and instability, cyclohexyne cannot be isolated under normal conditions and exists only as a short-lived reactive intermediate in certain organic reactions. [2]

Contents

Synthesis

Cyclohexyne cannot be stored or isolated due to its extreme instability. It is generated in situ through the elimination of hydrogen halides from suitable precursors. [3] Other methods include the use of organolithium reagents or photolytic or thermal activation of precursor molecules. [4]

Cyclohexyne as a complex ligand

The formation of metal complexes stabilizes cyclohexyne. A platinum complex of cyclohexyne can be prepared by elimination from 1-bromocyclohexene with lithium diisopropylamide in the presence of tris(triphenylphosphine)platinum(0). [5] An alternative synthetic method is the reduction of 1,2-dibromocyclohexene with sodium amalgam in the presence of tris(triphenylphosphine)platinum(0). [6] Such a complex can also be prepared by trapping with tris(triphenylphosphine)platinum(0) when cyclohexenylphenyliodonium tetrafluoroborate is used as the starting material for cyclohexyne.

Another complex, in this case with zirconium, can be prepared starting from methylzirconocene chloride by reacting it first with cyclohexenyllithium and then with trimethylphosphine. [7]

References

  1. ↑ Parker, W. (31 October 2007). Alicyclic Chemistry: Volume 5. Royal Society of Chemistry. p. 248. ISBN   978-1-84755-548-9 . Retrieved 29 July 2025.
  2. ↑ Cava, M. P. (2 December 2012). Cyclobutadiene and Related Compounds. Elsevier. p. 17. ISBN   978-0-323-16312-5 . Retrieved 29 July 2025.
  3. ↑ Wiberg, Egon; Wiberg, Nils (2001). Inorganic Chemistry. Academic Press. p. 1613. ISBN   978-0-12-352651-9 . Retrieved 29 July 2025.
  4. ↑ Chari, Jason V.; Ippoliti, Francesca M.; Garg, Neil K. (15 March 2019). "Concise Approach to Cyclohexyne and 1,2-Cyclohexadiene Precursors". The Journal of Organic Chemistry . 84 (6): 3652–3655. doi:10.1021/acs.joc.8b03223. ISSN   0022-3263. PMID   30840455 . Retrieved 29 July 2025.
  5. ↑ Lu, Zheng; Abboud, Khalil A.; Jones, W. M. (1 April 1993). "Platinum(0) complexes of cyclic alkynes and allenes from base-induced dehydrohalogenation of bromocycloalkenes". Organometallics . 12 (4): 1471–1474. doi:10.1021/om00028a079. ISSN   0276-7333 . Retrieved 7 August 2025.
  6. ↑ Gampe, Christian M.; Carreira, Erick M. (2012). "Arynes and Cyclohexyne in Natural Product Synthesis". Angewandte Chemie International Edition . 51 (16): 3766–3778. doi:10.1002/anie.201107485. ISSN   1521-3773 . Retrieved 7 August 2025.
  7. ↑ Buchwald, Stephen L.; Lum, Robert T.; Dewan, John C. (1 November 1986). "Synthesis, structure, and reactions of a zirconocene-cyclohexyne complex". Journal of the American Chemical Society . 108 (23): 7441–7442. doi:10.1021/ja00283a068. ISSN   0002-7863 . Retrieved 7 August 2025.
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