Electrophilic Addition

    Cards (5)

    • What is electrophilic addition reactions?
      C=C double bond forms an area of high electron density which can be attacked by positively charged reagents called electrophiles
      Electrophiles are electron pair accepters which must have a full positive charge or δ+
    • What are the steps of the mechanism?
      1. Add any partial charges from polar bonds or from induced dipole -> δ+ and δ-
      2. Draw an arrow to show the movement of electrons from the double bond and single bond
      3. Add ions and any lone pairs
      4. Label the carbocation formed
      5. Draw an arrow to show the movement of electrons from the lone pair to the carbocation
    • What happens when there are asymmetrical alkenes?
      More than one product could be formed
      Can determine which product is the major product by looking at the number of alkyl groups
      The more alkyl groups attached to the positively charged carbon atoms, the more stable to carbocation is
      Tertiary carbocation > secondary carbocation > primary carbocation

      Major product is formed via a _ carbocation which is more stable than a _ carbocation
    • What is the positive inductive effect?
      Alkyl groups can release electrons which can stabilise the positive charge of the carbocation
    • How do alkenes react with sulphuric acid?
      Alkenes produce alcohols by using a sulphuric acid catalyst and water - occurs at room temperature and is an exothermic reaction
      The electrophile is the δ+ hydrogen atom in the sulphuric acid molecule
      Hδ+OδSO3HH^{δ+}-O^{δ-}-SO_3H
      The carbocation formed reacts with the hydrogensulphate ion to form _thyl hydroensulphate
      This is reacted with water to produce an alcohol, and the sulphuric acid reforms as it is not used up