Norbornene or norbornylene or norcamphene is a highly strained bridged cyclic

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...

. It is a white solid with a pungent sour odor. The

molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and b ...

consists of a

cyclohexene Cyclohexene is a hydrocarbon with the formula C6H10. This cycloalkene is a colorless liquid with a sharp smell. It is an intermediate in various industrial processes. Cyclohexene is not very stable upon long term storage with exposure to light ...

ring with a methylene bridge between carbons 1 and 4. The molecule carries a double bond which induces significant

ring strain In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles are ...

and significant reactivity.

Production

Norbornene is made by a Diels–Alder reaction of cyclopentadiene and

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene ...

. Many substituted norbornenes can be prepared similarly. Related bicyclic compounds are norbornadiene, which has the same carbon skeleton but with two double bonds, and

norbornane Norbornane (also known as bicyclo .2.1eptane) is an organic compound and a saturated hydrocarbon with chemical formula C7H12. It is a crystalline compound with a melting point of 88 °C. The carbon skeleton is derived from cyclohexane ring with ...

which is prepared by

hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic ...

of norbornene.

Reactions

Norbornene undergoes an acid-catalyzed

hydration reaction In chemistry, a hydration reaction is a chemical reaction in which a substance combines with water. In organic chemistry, water is added to an unsaturated substrate, which is usually an alkene or an alkyne. This type of reaction is employed indust ...

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

Polynorbornenes

Norbornenes are important

monomer In chemistry, a monomer ( ; '' mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Classification ...

s in ring-opening metathesis polymerizations (ROMP). Typically these conversions are effected with ill-defined catalysts. Polynorbornenes exhibit high

glass transition temperature The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle "glassy" state into a viscous or ru ...

s and high optical clarity. : Polynbornene

In addition to ROMP, norbornene monomers also undergo vinyl-

addition polymerization Chain-growth polymerization ( AE) or chain-growth polymerisation ( BE) is a polymerization technique where unsaturated monomer molecules add onto the active site on a growing polymer chain one at a time. There are a limited number of these acti ...

, and is a popular monomer for use in cyclic olefin copolymers. Polynorbornene is used mainly in the rubber industry for antivibration (rail, building, industry), antiimpact (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 1,3-Butadiene () is the organic compound with the formula (CH2=CH)2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two v ...

References

{{Authority control Monomers Norbornanes