Chapter 12 :  Reactions of Arenes. Electrophilic Aromatic Substitution

Clemmensen Reduction (acidic conditions)

• Zn(Hg) in HCl reduced the C=O into -CH₂-

• NH₂NH₂ / KOH / ethylene glycol (a high boiling solvent)  reduces the C=O into -CH₂-

• These reduction methods do not reduce C=C or C≡C nor -CO₂H
• The combination of either one of these methods after a Friedel-Crafts acylation gives the equivalent of alkylation but without the problems and complications associated with carbocation rearrangements.
• The choice of method should be made based on the tolerance of other functional groups in the system to the acidic or basic reaction conditions.

© Dr. Ian Hunt, Department of Chemistry