Grignard Addition to a Ketone

1
Grignard Addition to a Ketone

• Our Goals Today
• Learn the how to make a Grignard reagent.
• Learn how to run a Grignard reaction
• Learn the mechanism and scope of the reaction.

2
Formation of Grignard Reagent
Nucleophilic bond
Stabilized in ethereal solvent
Unstable in water (acid too)

• Can think of the Mg as inserting into the R-X
  bond
• Grignard reagent alkyl delivery agent
• Alkyl group nucleophile
• Stabilized in ethereal solvents
• Unstable in water

3
Delivery of the Alkyl Group

• The reaction step forms the magnesium salt of
  the alcohol.
• The protonation step occurs during the
  work-up (extraction / washing).

4
Grignard Reaction of Carbonyls
1
2
3
Two Grignard Equivalent
One Grignard Equivalent
5
Our Grignard Reaction
Our Grignard Reagent
Triphenyl Methanol
6
Your Task

• Run the reaction.
• Isolate crude product and save in flask until
  next lab period.

7
Advisory

• If you have over 2g of benzophenone then just use
  2g.
• If you have 1 - lt2g of benzophenone then scale
  the reaction.
• If you have lt1g of benzophenone then get extra
  from prof.
• Make sure you do not wash you glassware before
  the reaction.
• Keep all sources of water away from reaction.
• The TAs will dispense the anhyrdous ether for
  the reaction.
• The regular ether in the dispensing hood
  shouldnt be used for the reaction.
• Save your crude product until the next lab
  period.
• Clean up after yourselves!