Norbornene

Norbornene[1]
Names
Preferred IUPAC name
Bicyclo[2.2.1]hept-2-ene
Other names
Norbornylene
Norcamphene
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.007.152
EC Number 207-866-0
Properties
C7H10
Molar mass 94.16 g·mol−1
Appearance White solid
Melting point 42 to 46 °C (108 to 115 °F; 315 to 319 K)
Boiling point 96 °C (205 °F; 369 K)
Hazards
NFPA 704
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasolineHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroformReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calciumSpecial hazards (white): no codeNFPA 704 four-colored diamond
3
2
1
Flash point −15 °C (5 °F; 258 K)
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

Norbornene or norbornylene or norcamphene is a bridged cyclic hydrocarbon. It is a white solid with a pungent sour odor. The molecule consists of a cyclohexene ring with a methylene bridge between carbons 1 and 4. The molecule carries a double bond which induces significant ring strain and significant reactivity.

Production

Norbornene is made by a Diels–Alder reaction of cyclopentadiene and ethylene. Many substituted norbornenes can be prepared similarly.[2][3] Related bicyclic compounds are norbornadiene, which has the same carbon skeleton but with two double bonds, and norbornane which is prepared by hydrogenation of norbornene.

Reactions

Norbornene undergoes an acid-catalyzed hydration reaction to form norborneol. This reaction was of great interest in the elucidation of the non-classical carbonion controversy.

Norbornene is used in the Catellani reaction and in norbornene-mediated meta-C−H activation.[4]

Certain substituted norbornenes undergo unusual substitution reactions owing to the generation of the 2-norbornyl cation.

Polynorbornenes

Norbornenes are important monomers in ring-opening metathesis polymerizations (ROMP). Typically these conversions are effected with ill-defined catalysts. Polynorbornenes exhibit high glass transition temperatures and high optical clarity.[5]

ROMP reaction giving polynorbornene. Like most commercial alkene metathesis processes, this reaction does not employ a well-defined molecular catalyst.

In addition to ROMP, norbornene monomers also undergo vinyl-addition polymerization.

Polynorbornene is used mainly in the rubber industry for anti-vibration (rail, building, industry), anti-impact (personal protective equipment, shoe parts, bumpers) and grip improvement (toy tires, racing tires, transmission systems, transports systems for copiers, feeders, etc.)

Ethylidene norbornene is a related monomer derived from cyclopentadiene and butadiene.

References

  1. ↑ Norbornene MSDS
  2. ↑ Binger, Paul; Wedemann, Petra; Brinker, Udo H. "Cyclopropene: A New Simple Synthesis and its Diels-Alder Reaction with Cyclopentadiene". Organic Syntheses. ; Collective Volume, 10, p. 231
  3. ↑ Oda, Masaji; Kawase, Takeshi; Okada, Tomoaki; Enomoto, Tetsuya. "2-Cyclohexene-1,4-dione". Organic Syntheses. ; Collective Volume, 9, p. 186
  4. ↑ Thansandote, Praew; Chong, Eugene; Feldmann, Kai-Oliver; Lautens, Mark (21 May 2010). "Palladium-Catalyzed Domino C−C/C−N Coupling Using a Norbornene Template: Synthesis of Substituted Benzomorpholines, Phenoxazines, and Dihydrodibenzoxazepines". The Journal of Organic Chemistry. 75 (10): 3495–3498. doi:10.1021/jo100408p. PMID 20423091.
  5. ↑ Delaude, Lionel; Noels, Alfred F. (2005). "Metathesis". Kirk-Othmer Encyclopedia of Chemical Technology. Weinheim: Wiley-VCH. doi:10.1002/0471238961.metanoel.a01.
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