6.2.11 - Addition to Unsymmetrical Alkenes

• unsymmetrical alkenes

  alkene where two carbon atoms in the double bond have different groups attached to them
• what happens during the addition reaction with unsymmetrical alkenes?

  two possible products are formed - major and minor
• what does the amount of each product formed in addition reactions of unsymmetrical alkenes depend on?

  stability of carboncation and mechanism
• Markovnikov's rule

  when a hydrogen halide is added to an unsymmetrical alkene, the hydrogen becomes attached to the carbon on the double bond with the most hydrogens attached to it already
• inductive effect in carboncations

  the way electrons are either pushed towards or pulled away from the carbon atom by the atoms or groups it's bonded to
• positive inductive effect

  alkyl groups push electrons towards the carbon they are bonded to
• negative inductive effect

  pulling force on the electrons away from the carbon atom group is bonded to
• what affect inductive effect?

  electronegativity: high electronegativity means a negative inductive effect
• what does stability of carboncations depend on?

  the number of alkyl groups attached to the carbon

  the more alkyl groups the more stable because each alkyl group exerts a positive inductive effect on the carbon so pushes electrons to positive charge reducing it

  the more stable carboncation is more likely to form
• types of carboncations

  primary

  secondary

  tertiary
• primary carboncation

  has one alkyl group attached to C+
• secondary carboncation

  has two alkyl groups attached to C+ so is more stable than primary carboncation
• tertiary carboncation

  has three alkyl groups attached to C+ so is more stable than primary and secondary carboncation