13.3 Reactions Of Alkenes Flashcards
Are alkenes more or less reactive than alkanes?
Much more reactive
Why are alkenes so reactive?
-Because of the presence of the pi-bond.
-It is on the outside of the double bond, so the pi-electrons are more exposed than the electrons in the sigma-bond.
-The pi-bond is weaker than the sigma-bond, and readily breaks, meaning the alkenes can undergo addition reactions relatively easily.
What are the conditions needed for a hydrogen to react with an alkene in an addition reaction?
High temperatures, and need to be passed over a nickel catalyst.
What is the term for the addition reaction between hydrogen and an alkene?
Hydrogenation.
What are the conditions required for an alkene to react with a halogen?
Room temperature and pressure. Absence of light
What is the term for the addition reaction between a halogen and an alkene?
Halogenation.
What two halogens most commonly react with an alkene?
Bromine and Chlorine
What can the reaction of an alkene with bromine be used to identify?
If there is a C=C bond present, and the organic compound is unsaturated.
What happens when bromine reacts completely with an alkene?
It goes from orange to colourless. Decolourises bromine water.
What are the conditions required for an alkene to react with a hydrogen halide?
Room temperature.
How does a hydrogen halide react with an alkene if the alkene is liquid and the hydrogen halide is a gas?
The hydrogen halide is bubbled through the liquid.
How are alcohols formed?
When alkenes react with steam in the presence of a phosphoric catalyst (H3PO4)
