Cyclooctadecanonaene

Cyclooctadecanonaene

Identifiers
InChI InChI=1S/C18H18/c1-2-4-6-8-10-12-14-16-18-17-15-13-11-9-7-5-3-1/h1-18H/b2-1-,3-1+,4-2+,5-3+,6-4+,7-5-,8-6-,9-7+,10-8+,11-9+,12-10+,13-11-,14-12-,15-13+,16-14+,17-15+,18-16+,18-17- Key: STQWAGYDANTDNA-DWSNDWDZSA-N
Properties
Molecular formula	C18H18
Molar mass	234.34 g·mol−1
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

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

• Superbenzene

References

1. ↑ Ivanov, A.; Boldyrev. A (2014). "Deciphering aromaticity in porphyrinoids via adaptive natural density partitioning". Org. Biomol. Chem. doi:10.1039/C4OB01018C. 
2. ↑ In the literature and some internet references, Sondheimer is sometimes misspelled as Sandheimer.
3. ↑ 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. 
4. ↑ K. Stöckel and F. Sondheimer (1988). "[18]Annulene". Org. Synth. ; Coll. Vol. 6, p. 68