Advices For Studying Organic Chemistry

1) Grignard reagents react primarily at the less-substituted ring carbon of

substituted oxirane.

Specific Examples

H 2 C CH

O

+ OMgBr H O

+

Et 2 O^2 CH^2 CH H

CH 3

CH 3 CH 3

C 6 H 5 MgBr C 6 H 5 CH C 6 H 5 CH

12.7C REACTIONS OF GRIGNARD REAGENTS

WITH CARBONYL COMPOUNDS

1. The most important reactions of Grignard reagents and organolithium compounds
   are the nucleophilic attack to the carbonyl group.

A Mechanism for the Reaction

The Grignard Reaction
Reaction:

RMgX + CO1. ether R

2. H 3 O+X −

C O H + MgX 2

Mechanism:
Step 1

CO R C O −

δ−

R +

δ+

MgX

Grignard reagentCarbonyl compound Halomagnesium alkoxide

Mg2+X −

The strongly nucleophilic Grignard reagent uses its electron pair to form a bond to

the carbon atom. One electron pair of the carbonyl group shifts out to the oxygen.

This reaction is a nucleophilic addition to the carbonyl group, and it results in the

formation of an alkoxide ion associated with Mg2+ and X−.

Step 2