Reactivity of Alkenes
- Alkenes are hydrocarbons containing a carbon-carbon double bond
- The atoms around the carbon-carbon double bond adopt a planar arrangement and the bond angle is 120o
The bonding arrangement around a carbon-carbon double bond
- The presence of the C=C bond gives alkenes a number of chemical properties that are not seen in alkanes
- Since the alkene contains π-bonds, it is possible to break the weaker π-bond and form stronger σ-bonds with other species without forcing any atoms on the molecule to break off
- As a result alkenes (unlike alkanes) are capable of undergoing addition reactions
Addition reactions in alkenes
- Molecules which contain π-bonds and which can hence undergo addition are said to be unsaturated
- Molecules which do not contain π-bonds and which hence cannot undergo addition are said to be saturated.
- Alkenes are unsaturated and can hence undergo addition
- Addition is the combination of two or more molecules to form a single molecule
- Addition reactions are generally faster than substitution reactions since only weak π-bonds are broken, rather than stronger σ-bonds
- The ability of alkenes to undergo addition means that they are much more reactive than alkanes
