This topic is part of F322 AS OCR A Chemistry. There are five different reactions that you need to know involving the reaction with alkenes.
I have summarised all the reactions in this diagram/mind map I made below:
1. Reaction with halogens/ Halogen addition reactions
- Electrophilic Addition
- This is a test for unsaturation.
- The observation: decolourisation.
- Unsaturated hydrocarbons decolourise bromine water.
2. Reaction with a halogen halide
- e.g. HCl
- Electrophilic Addition
3. Reaction with Hydrogen / Hydrogenation
- A Nickel (Ni) Catalyst is used
- Requires High temperatures and pressures (About 150°C)
- Used in the manufacture of margarine from animal or vegetable fats and oils.
4. Reaction with water
- The water must be in gaseous state - H₂O (g) - Steam
- High Temperatures
- Catalyst: Phosphoric Acid (H₃PO₄)
- Product: An Alcohol
5. Addition Polymerisation
- Many monomers (unsaturated), bond together by the double bond.
- The double bond opens up and joins to other monomers to form ONE large molecule called a POLYMER.
