Yesterday we started electrophilic aromatic substitution reactions, or EAS. The concept was generally this -- benzene is pretty unreactive as a Lewis Base, so in order to get it to react we need to increase the Lewis Acidity of the other reagent. This we did by using a separate Lewis Acid (with halides it was an iron halide) to put a positive charge on one of the halogen atoms (just like protonating -OH to make it water). We also saw that the carbocation intermediate, although losing stability due to loss of aromatic character, is somewhat stabilized by resonance. The reaction is finished off by deprotonation to regenerate the aromatic character of the ring.
A key for the exam has been posted to the left.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment