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Module 4 Chapter 13 (13.4 Electrophilic addition (Mechanism HBr and But…

- - - - Contain C=C bond
      - Have 2 different groups attached to each carbon of the C=C
  - - - Molecule must contain a C=C bond
      - Each carbon in the C=C must be connected to two different groups
      - One group on each carbon must be identical
- - - - Alkene + Hydrogen + Nickel Catalyst -> Alkane
      - e.g. Propene + Hydrogen -> Propane
      - All C=C bonds break- have to balance number of hydrogens to account for molecules with multiple C=C
    - - Alkene + Chlorine/Bromine -> Di(bromo/chloro)alkane
      - e.g. Propene + Bromine -> Dibromopropane
      - Test
        
        If a molecule is unsaturated (contains C=C), when Bromine water is added and shaken it goes from orange to colourless
    - - Alkene + Hydrogen halide (gas)-> Haloalkane
      - e.g. Propene + HCl -> Chloropropane
      - If the alkane is unsymmetrical there are two possible products depending on which side of the C=C the hydrogen is added
    - - Alkenes react with steam in the presence of a phosphoric acid catalyst (H3PO4)
      - Alkene + Steam + Phosphoric acid catalyst -> Alcohol
      - e.g. Propene + Steam -> Propanol
      - Used in industry to produce ethanol from ethene
      - If unsymmetrical alkene then 2 possible products
- - - - Favoured product= major Other product= minor
      - Hydrogen of the hydrogen halide attaches itself in preference to the carbon with the most hydrogens and the fewest alkyl groups
      - If the non-hydrogen attaches to the 1st carbon in the C=C = primary, if it attaches to the 2nd= secondary
    - - More alkyl groups connected to positive carbon, more stable the molecule is because of the electron donating ability of alkyl groups- they push electrons towards the positive charge of the carbocation so the more alkyl groups, the more the charge is spread out so the more stable the carbocation is