SN1 v SN2: Leaving group

• what are the two factors to consider with halides as leaving groups?

  C-X bond strength and halide anion stability
• Why do alcohols and ethers no react with nucleophiles?

  pKa of leaving group is too high so not a good leaving group
• how to turn alcohol into good leaving groups?

  protonate with strong acid or transform OH into a sulfonate ester
• What is used to convert an alcohol to a sulfonate ester?

  Tosyl chloride, pyridine
• Why is tosylate a good leaving group?

  Negative charge delocalised on three oxygen atoms: stabilised
• how are ethers as leaving groups?

  poor (pka 16), need activation by a strong acid or lewis acid
• Describe the properties of strained ethers:

  • strained (internal angle 60)
  • sp3 hydridised
  • very large deviation from ideal tetrahedral angle: angle strain
• what happens to epoxides in acidic conditions?

  protonated, react the same way as linear ethers
• what type of reaction makes an epoxide?

  sn2