Benzvalene
Chemical compound
From Wikipedia, the free encyclopedia
Benzvalene is an organic compound and one of several isomers of benzene.[1] It was first synthesized in 1967 by K. E. Wilzbach et al. [2] via photolysis of benzene and the synthesis was later improved by Thomas J. Katz et al.[3][4]
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| Preferred IUPAC name
Tricyclo[3.1.0.02,6]hex-3-ene | |
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3D model (JSmol) |
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CompTox Dashboard (EPA) |
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| Properties | |
| C6H6 | |
| Molar mass | 78.114 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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The 1971 synthesis consisted of treating cyclopentadiene with methyllithium in dimethyl ether and then with dichloromethane and methyllithium in dimethyl ether at −45 °C.[4] It can also be formed in low yield (along with fulvene and Dewar benzene) by irradiation of benzene at 237 to 254 nm.[5] The hydrocarbon in solution was described as having an extremely foul odor. Due to the high steric strain present in benzvalene, the pure compound (~71 kcal/mol higher in energy than benzene) easily detonates, for example by scratching.
The compound converts to benzene with a chemical half-life of approximately 10 days. This symmetry-forbidden transition is believed to take place through a diradical intermediate.[6]
Polybenzvalene
Benzvalene can be polymerized in a ring opening metathesis polymerisation to polybenzvalene.[7] This polymer contains highly strained bicyclobutane rings which again makes it a sensitive material. The rings can be isomerized to 1,3-dienes and for this reason polybenzvalene has been investigated as a precursor to polyacetylene.
