Radialene

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[n]Radialenes are alicyclic organic compounds containing n cross-conjugated exocyclic double bonds. The double bonds are commonly alkene groups but those with a carbonyl (C=O) group are also called radialenes ^[1]. For some members the unsubstituted parent radialenes are elusive but many substituted derivatives are known.

Radialenes are related to open-chain dendralenes and also to compounds like butadiene and benzene which also consist of a ring of sp² hydridized carbon atoms.

Radialenes are investigated in organic chemistry for their unusual properties and reactivity but have not ventured outside the laboratory.

Contents 1 Conformation 2 Synthesis & properties 2.1 [4]Radialene 3 References

[edit] Conformation

[3] and [4]radialenes are expected to have a planar molecular geometry with all carbon atoms in the same plane. This is verified experimentally in hexamethyl[3]radialene and cyclobutanetetraonetetrakis(hydrazone). Decamethyl[5]radialene has a twist envelope geometry with C₂ symmetry while a chair conformation is calculated for [6]radialene and found experimentally for hexa-(ethylidene)cyclohexane

[edit] Synthesis & properties

[edit] [4]Radialene

The unsubstituted [4]radialene has been prepared in an elimination reaction of cis,trans,cis-tetra(bromomethyl)cyclobutane with sodium methoxide in ethanol ^[2]

Hydrogenation with platinum on carbon gives cis,cis,cis-tetramethylcyclobutane in accordance with the proposed structure. On standing in air at room temperature the compound accepts oxygen and polymerizes.

[edit] References