Grignard reaction

In the Merck Index, published online by the Royal Society of Chemistry, the classical definition is acknowledged, followed by "A more modern interpretation extends the scope of the reaction to include the addition of Grignard reagents to a wide variety of electrophilic substrates.

The addition of the Grignard reagent to the carbonyl group typically proceeds through a six-membered ring transition state, as shown below.

[11] A recent computational study suggests that the operative mechanism (polar vs. radical) is substrate-dependent, with the reduction potential of the carbonyl compound serving as a key parameter.

[3] Otherwise, the reaction will fail because the Grignard reagent will act as a base rather than a nucleophile and pick up a labile proton rather than attacking the electrophilic site.

This will result in no formation of the desired product as the R-group of the Grignard reagent will become protonated while the MgX portion will stabilize the deprotonated species.

A solution of a carbonyl compound is added to a Grignard reagent. (See gallery )
An example of a Grignard reaction (R 2 or R 3 could be hydrogen)
Although Grignard reagents undergo many reactions, the classical Grignard reaction refers only to the reaction of RMgX with ketones and aldehydes, shown in red. X = Cl, Br, I.
Reactions of Grignard reagents with various electrophiles
Additional reactions which involve Grignard reagents, but are not considered to be Grignard reactions by the classical definition. X = Cl, Br, I.
The mechanism of the Grignard reaction.
The mechanism of the Grignard reaction.
If a Grignard reaction is performed in the presence of water, or any labile proton, the labile proton will quench the Grignard reagent as shown in the figure above. [ 3 ]
An example reaction of forming a Turbo-Grignard with an ester group.
A conjugated 1,4 addition using a Gilman reagent with an arbitrary R group