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Names | |
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Preferred IUPAC name
Bicyclo[4.4.1]undeca-1,3,5,7,9-pentaene | |
Identifiers | |
3D model (
JSmol)
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ChemSpider | |
PubChem
CID
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CompTox Dashboard (
EPA)
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Properties | |
C11H10 | |
Molar mass | 142.201 g·mol−1 |
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
|
1,6-Methano[10]annulene (also known as 1,6-methanonaphthalene or homonaphthalene) is an aromatic hydrocarbon with chemical formula C11H10. It was the first stable aromatic compound based on the cyclodecapentaene system to be discovered.
The classical organic synthesis of this compound starts with Birch reduction of naphthalene to isotetralin, which adds dichlorocarbene (prepared in situ from chloroform and potassium tert-butoxide) to form a transannular cyclopropane ring. A second reduction then removes the chloride substituents. Finally, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) oxidation removes the central transannular bond and dehydrogenates unto aromaticity. [1]
It is analogous to
cyclodecapentaene ([10]annulene), but with two hydrogen atoms replaced by a transannular
methylene bridge (-CH
2-). Consequently, it obeys
Hückel's rule (n = 2) and despite the distortion from planarity introduced by the methylene bridge, the compound is
aromatic.
[2]
[3] In fact, when prepared by Vogel in the 1960s
[4]
[5] it was the first stable aromatic cyclodecapentaene to be discovered.
[3] Its
aromaticity is confirmed by two main pieces of evidence. Firstly, the similarity in carbon-carbon
bond lengths as measured by
x-ray crystallography is inconsistent with alternating
single and
double bonds. The actual structure is better considered as a pair of
resonance hybrids (like the
Kekulé structures of benzene) rather than as having alternating single and double bonds.
Secondly, its 1H NMR spectrum displays influence of the diamagnetic ring current which is characteristic of aromatic compounds. The peripheral protons around the ring are deshielded while the methylene bridge nuclei are strongly shielded. [2] [3]
Its resonance energy is smaller than that of naphthalene. [6]
Homonaphthalene has been used in the production of conductive polymers. [7]
![]() | |
Names | |
---|---|
Preferred IUPAC name
Bicyclo[4.4.1]undeca-1,3,5,7,9-pentaene | |
Identifiers | |
3D model (
JSmol)
|
|
ChemSpider | |
PubChem
CID
|
|
CompTox Dashboard (
EPA)
|
|
| |
| |
Properties | |
C11H10 | |
Molar mass | 142.201 g·mol−1 |
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
|
1,6-Methano[10]annulene (also known as 1,6-methanonaphthalene or homonaphthalene) is an aromatic hydrocarbon with chemical formula C11H10. It was the first stable aromatic compound based on the cyclodecapentaene system to be discovered.
The classical organic synthesis of this compound starts with Birch reduction of naphthalene to isotetralin, which adds dichlorocarbene (prepared in situ from chloroform and potassium tert-butoxide) to form a transannular cyclopropane ring. A second reduction then removes the chloride substituents. Finally, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) oxidation removes the central transannular bond and dehydrogenates unto aromaticity. [1]
It is analogous to
cyclodecapentaene ([10]annulene), but with two hydrogen atoms replaced by a transannular
methylene bridge (-CH
2-). Consequently, it obeys
Hückel's rule (n = 2) and despite the distortion from planarity introduced by the methylene bridge, the compound is
aromatic.
[2]
[3] In fact, when prepared by Vogel in the 1960s
[4]
[5] it was the first stable aromatic cyclodecapentaene to be discovered.
[3] Its
aromaticity is confirmed by two main pieces of evidence. Firstly, the similarity in carbon-carbon
bond lengths as measured by
x-ray crystallography is inconsistent with alternating
single and
double bonds. The actual structure is better considered as a pair of
resonance hybrids (like the
Kekulé structures of benzene) rather than as having alternating single and double bonds.
Secondly, its 1H NMR spectrum displays influence of the diamagnetic ring current which is characteristic of aromatic compounds. The peripheral protons around the ring are deshielded while the methylene bridge nuclei are strongly shielded. [2] [3]
Its resonance energy is smaller than that of naphthalene. [6]
Homonaphthalene has been used in the production of conductive polymers. [7]