SN2 Mechanism

Time to start learning about some of the most important reactions in all of organic chemistry. In fact, you’re never allowed to forget this one!

Summary: A negatively charged nucleophile reacts with an accessible leaving group to produce substitution in one-step.

Properties of SN2 reactions:

  • Nucleophile =  Strong
  • Leaving Group =  Unsubstituted
  • Reaction coordinate = Transition State
  • Reaction = Concerted
  • Rate =  Bimolecular
  • Rate =  k[Nu][RX]
  • Stereochemistry = Inversion
  • Nickname = Back-side attack!

Example: Rank the following alkyl halides in order of reactivity toward SN2 reaction. 


Problem: Predict the product of the following reaction.


The product must contain inversion of configuration if the original leaving group is located on a chiral center. 

Problem: Predict the product of the following reaction: