Spiropentadiene, or bowtiediene, is a hydrocarbon with formula C
5H
4. The simplest spiro-connected diene, it is very unstable—decomposing even below −100 °C—due to its high bond strain and does not occur in nature. Its synthesis was reported in 1991.[1][2]
Names | |
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Preferred IUPAC name
Spiro[2.2]penta-1,4-diene | |
Other names
Bowtiediene; Spiropenta-1,4-diene
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Identifiers | |
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3D model (JSmol)
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ChemSpider |
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PubChem CID
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CompTox Dashboard (EPA)
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Properties | |
C5H4 | |
Molar mass | 64.087 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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Infobox references
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Spiropentadiene was synthesised from bistrimethylsilylpropynone 1 by reaction with p-toluenesulfonylhydrazide to tosylhydrazone 2 followed by treatment with sodium cyanoborohydride to allene 3 and followed by two successive reactions with chlorocarbene generated from methyllithium and dichloromethane to spiro compound 5. Spiropentadiene was trapped in a liquid nitrogen trap after reaction with TBAF in a double elimination reaction.
The derivative dichlorospiropentadiene has been reported.[3] An all-silicon derivative (Si5 frame, (tBuMe2Si)3Si side groups) is also known.[4] In contrast to the carbon parent this compound is stable with a melting point of 216 to 218 °C. The angle between the two rings as measured by X-ray single-crystal analysis is 78°.