CH 12-3: Grignard Reaction-I
•Important multi-step synthesis for making new C-C bonds,
and 1o, 2o, and 3o alcohols.
•The 3-step series of reactions includes the unique reaction
of an alkyl halide (R-X) with magnesium metal (Mg) to form a
C-Mg “organic-metallic” bond:
•The “Grignard Reagent” is essentially a carbon nucleophile
in the form of a coordinate covalent bond.
•The Grignard Reagent then reacts with an oxygen
compound (aldehyde, ketone, ester, epoxide) to produce a
new C-C bond and an alcohol.
Grignard Reaction
•General reaction (three parts):
Grignard Reaction – Step by step
Part I. For carbon to be a nucleophile it must be activated by
forming an organometallic compound (Grignard Reagent).
X
C
1o, 2o, 3o
X
C
X
C
vinyl halide
phenyl halide
Alkyl halides react with Mg metal in ether solvent to form
the “Grignard Reagent” containing a coordinate covalent
bond. The metal stabilizes the carbon-anion.
Part II. The Grignard reagent is:
(1) a strong base
(2) a good nucleophile
The key reaction is addition to electrophilic C-O compounds
to form alcohols:
Grignard reagent
Part III. Add dilute acid to neutralize the basic salt.