What is the Difference Between Exocyclic and Endocyclic Double Bond?

The main difference between exocyclic and endocyclic double bonds lies in the location of the carbon atoms involved in the double bond within the ring structure of the molecule.

• Exocyclic Double Bonds: These double bonds have only one of the two carbon atoms involved in the bond as part of the ring structure. The other carbon atom is located outside the ring. Exocyclic double bonds can be observed in unsaturated organic compounds, specifically in alkenes. For example, methylenecylopentane is an example of an exocyclic double bond.
• Endocyclic Double Bonds: These double bonds have both carbon atoms involved in the bond as part of the ring structure. Endocyclic double bonds are located within the ring structure, meaning they are part of the ring itself. Cyclopentene is an example of an endocyclic double bond.

In summary:

• Exocyclic double bonds have one carbon atom in the ring and one carbon atom outside the ring.
• Endocyclic double bonds have both carbon atoms in the ring.

Comparative Table: Exocyclic vs Endocyclic Double Bond

Exocyclic and endocyclic double bonds are both covalent chemical bonds containing two carbon atoms bonded to each other via a sigma (σ) bond and a pi (π) bond. However, they differ in the position of the carbon atoms within the cyclic structure. Here is a summary of their differences:

Examples of compounds containing exocyclic double bonds include methylcyclohexane and methylenecylopentane. An example of a compound containing an endocyclic double bond is cyclopentene.