Norbornene

Norbornene is a bicyclic hydrocarbon with seven carbons, commonly named bicyclo[2.2.1]hept-2-ene. It features a rigid, bridged framework in which a single double bond is embedded in the bicyclic system, giving significant ring strain. This strain makes the alkene unusually reactive in certain types of cycloadditions and in ring-opening metathesis polymerization. Norbornene and many of its derivatives are colorless liquids or low-melting solids at ambient conditions.

The principal method for producing norbornene is the Diels–Alder reaction between cyclopentadiene and ethylene, which furnishes norbornene as the adduct. The compound can also be accessed via transformations of related bicyclic dienes such as norbornadiene, with the double bond position retained in the norbornene framework. Because of its strained alkene, norbornene readily participates in cycloadditions and acts as a dienophile in Diels–Alder reactions, as well as a monomer in polymerization processes.

Applications of norbornene arise largely from its use as a versatile building block in polymer chemistry. The monomer bearing the norbornene moiety is widely employed in ring-opening metathesis polymerization (ROMP) to produce well-defined polymers and resins with desirable thermal and mechanical properties. Derivatives of norbornene, such as norbornene dicarboximide, are used in specialty polymers, coatings, and electronics. The compound is handled under standard laboratory safety practices, as it is generally flammable and can act as an irritant.