What factors influence the reactivity of different alkenes?

The reactivity of different alkenes is influenced by their structure, electron density, and the type of substituents attached to them.

Alkenes are hydrocarbons that contain a carbon-carbon double bond. This double bond is the site of reactivity in alkenes, and its nature can significantly influence how an alkene reacts. The structure of the alkene, including the arrangement of atoms and the presence of any functional groups, can affect the stability of the double bond and thus the reactivity of the alkene.

The electron density around the double bond also plays a crucial role in determining the reactivity of an alkene. The double bond in alkenes consists of a sigma bond and a pi bond. The pi bond, which is formed by the sideways overlap of p orbitals, is weaker and more exposed than the sigma bond, making it more susceptible to attack by electrophiles - species that are attracted to regions of high electron density. Therefore, alkenes with a higher electron density around the double bond are generally more reactive.

The type of substituents attached to the carbon atoms of the double bond can also influence the reactivity of alkenes. Electron-donating groups, such as alkyl groups, can increase the electron density around the double bond and thus increase the reactivity of the alkene. On the other hand, electron-withdrawing groups, such as halogens or nitro groups, can decrease the electron density around the double bond and thus decrease the reactivity of the alkene.

In addition, the steric hindrance - the physical size and shape of the substituents - can affect the reactivity of alkenes. Larger substituents can hinder the approach of the electrophile to the double bond, making the alkene less reactive. Conversely, smaller substituents allow for easier access to the double bond, making the alkene more reactive.

In summary, the reactivity of different alkenes is influenced by a combination of factors, including their structure, electron density, and the type and size of substituents attached to them.