Cyclooctadecanonaene
Annulene.svg)
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Annulene_3D_ball.png)
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3D model (JSmol)
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| Properties | |
| C18H18 | |
| Molar mass | 234.342 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cyclooctadecanonaene or [18]annulene is an annulene with chemical formula C
18H
18. This hydrocarbon obeys Hückel's rule and is, therefore, an aromatic compound. Theoretical studies show that [18]annulene has only three completely delocalized π bonds associated with its aromaticity, while other six π bonds represent the conjugated 3c-2e π bonds on the periphery of [18]annulene.[1] The compound was first synthesised by Franz Sondheimer.[2]
Reactions
The original synthesis started by the Eglinton reaction of the di-alkyne 1,5-hexadiyne with copper(II) acetate in pyridine to give the trimer, followed by deprotonation and isomerization with potassium tert-butoxide in tert-butanol and was concluded with hydrogen organic reduction with the Lindlar catalyst.[3] [4]
See also
References
- ^ Ivanov, A.; Boldyrev. A (2014). "Deciphering aromaticity in porphyrinoids via adaptive natural density partitioning". Org. Biomol. Chem. doi:10.1039/C4OB01018C.
- ^ In the literature and some internet references, Sondheimer is sometimes misspelled as Sandheimer.
- ^ Sondheimer, F., Wolovsky, R. and Amiel, Y. (1962). "Unsaturated Macrocyclic Compounds. XXIII. The Synthesis of the Fully Conjugated Macrocyclic Polyenes Cyclooctadecanonaene ([18]Annulene), Cyclotetracosadodecaene ([24]Annulene), and Cyclotriacontapentadecaene ([30]Annulene)". J. Am. Chem. Soc. 68 (2): 274–284. doi:10.1021/ja00861a030.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ K. Stöckel and F. Sondheimer (1988). "[18]Annulene". Organic Syntheses; Collected Volumes, vol. 6, p. 68.