Benzvalene: Difference between revisions

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| PIN = Tricyclo[3.1.0.0^2,6]hex-3-ene

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| CASNo = 659-85-8

| PubChem = 136470

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| ChemSpiderID = 120239

| InChIKey = VMQPMGHYRISRHO-UHFFFAOYAJ

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| StdInChI = 1S/C6H6/c1-2-4-5-3(1)6(4)5/h1-6H

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| StdInChIKey = VMQPMGHYRISRHO-UHFFFAOYSA-N

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'''Benzvalene''' is an [[organic compound]] and one of several [[isomer]]s of [[benzene]].<ref>{{Cite journal| doi = 10.1002/anie.198105291| title = Benzvalene—Properties and Synthetic Potential| year = 1981| last1 = Christl | first1 = M.| journal = Angewandte Chemie International Edition in English| volume = 20| issue = 67| pages = 529–546}}</ref> It was first synthesized in 1967 by K. E. Wilzbach et al. <ref>{{Cite journal| doi = 10.1021/ja00980a053| title = Benzvalene, the Tricyclic Valence Isomer of Benzene| year = 1967| last1 = Wilzbach | first1 = K. E. | last2 = Ritscher | first2 = J. S. | last3 = Kaplan | first3 = L. | journal = [[Journal of the American Chemical Society]]| volume = 89| issue = 4| pages = 1031 }}</ref> via [[photolysis]] of [[benzene]] and the synthesis was later improved by Thomas J. Katz et al.<ref>{{Cite journal| doi = 10.1021/ja00744a045| title = Benzvalene synthesis| year = 1971| last1 = Katz | first1 = T. J.| last2 = Wang | first2 = E. J.| last3 = Acton | first3 = N.| journal = [[Journal of the American Chemical Society]]| volume = 93| issue = 15| pages = 3782 }}</ref><ref>{{Cite journal| doi = 10.1021/jo990883g| title = Synthesis of Benzvalene | year = 1999| last1 = Katz | first1 = T. J.| last2 = Roth | first2 = R. J.| last3 = Acton | first3 = N.| last4 = Carnahan | first4 = E. J.| journal = The Journal of Organic Chemistry| volume = 64| issue = 20| pages = 7663 }}</ref>

The 1971 synthesis consisted of treating [[cyclopentadiene]] with [[methyllithium]] in [[dimethyl ether]] and then with [[dichloromethane]] and methyllithium in [[diethyl ether]] at −45&nbsp;°C. It can also be formed in low yield (along with [[fulvene]] and [[Dewar benzene]]) by irradiation of benzene at 237 to 254 nm.<ref>{{Cite journal|last1=Kaplan|first1=Louis|last2=Wilzbach|first2=K. E.|date=1968-06-01|title=Photolysis of benzene vapor. Benzvalene formation at wavelengths 2537-2370 A|journal=Journal of the American Chemical Society|volume=90|issue=12|pages=3291–3292|doi=10.1021/ja01014a086|issn=0002-7863}}</ref> 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.<ref>{{Cite journal | doi = 10.1021/cr60276a004| title = Rearrangements and interconversions of compounds of the formula (CH)n| journal = Chemical Reviews| volume = 72| issue = 2| pages = 181| year = 1972| last1 = Scott| first1 = Lawrence T.| last2 = Jones| first2 = Maitland.}}</ref>

Benzvalene can be [[polymerized]] in a [[Ring opening metathesis polymerisation|ROMP]] process to '''polybenzvalene'''.<ref>{{Cite journal| doi = 10.1021/ja00217a049| title = Strained rings as a source of unsaturation: polybenzvalene, a new soluble polyacetylene precursor| year = 1988| last1 = Swager | first1 = T. M.| last2 = Dougherty | first2 = D. A.| last3 = Grubbs | first3 = R. H.| journal = Journal of the American Chemical Society| volume = 110| issue = 9| pages = 2973 }}</ref> This polymer contains highly strained [[bicyclobutane]] rings which again makes it a sensitive material. The rings can be [[isomerization|isomerized]] to 1,3-dienes and for this reason polybenzvalene has been investigated as a precursor to [[polyacetylene]].

==External links==

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[[Category:Explosive chemicals]]

[[Category:Cycloalkenes]]

[[Category:Tricyclic compounds]]

[[Category:Cyclopentenes]]

[[Category:Substances discovered in the 1970s]]