Elimination

• what is an E1 reaction?

  formation of a double bond
• what is E1 rate of reaction dependent on?

  concentration of substrate
• what interactions are involved in E1?

  HOMO-LUMO
• what is the orbital alignment of E1?

  C-H sigma orbital (HOMO) parallel to empty p orbital (LUMO) of carbocation
• What is the orbital alignment of E2?

  sigma orbital of broken C-H bond (HOMO) and C-Br sigma* (LUMO)
• what are the two possible alignments of E2?

  antiperiplanar and synperiplanar
• what is antiperiplanar?


  Attached groups are 180
• which is favoured antiperiplanar or synplanar?

  antiperiplanar
• what is the major product?

  more stabilised transition state
• what factors are involved in elimination:

  • substrate structure
  • basicity of nucleophile
  • size of nucleophile
  • temperature of reaction
• substrate structure:

  • good for sn1 good for E1
• what do strong bases give a preference for?

  E2
• what do large bulky hindered nucleophiles give rise to?

  E2
• what type of reaction do high temperatures favour?

  Elimination
• what do strong bases lead to?

  proton attack (hard Nu-hard electrophile interaction)

  leading to E2
• Is steric hindrance as big of a factor in E2?

  no, not as much as SN2
• why does a high temperature lead to elimination?

  entropy
• what does more negative Gibbs mean?

  fasters reaction
• what are good leaving groups in elimination reaction?

  halides, sulfonate ester
• how are quaternary amines made?

  E1 and E2
• how are quaternary ammonium salts made?

  Sn2