Question

Which of the following is not correct about Grignard reagent?

• A. It is a nucleophile
• B. Forms new carbon-carbon bond
• C. Reacts with carbonyl compounds
• D. It is an organomanganese compound

Hint:

Remember the general formula of a Grignard reagent (\( RMgX \)) and the key characteristics arising from the polar \( C-Mg \) bond, which makes the carbon nucleophilic and a strong base. Grignard reagents are organomagnesium compounds and are crucial for forming carbon-carbon bonds.

Answer 1

The Correct Option is D

A Grignard reagent has the general formula \( RMgX \), where \( R \) is an alkyl or aryl group, \( Mg \) is magnesium, and \( X \) is a halogen (Cl, Br, or I).
Let's evaluate each statement about Grignard reagents:
Option (A) **It is a nucleophile:** The carbon atom in the \( R \) group bonded to magnesium is highly electron-rich due to the significant electronegativity difference between carbon and magnesium (Mg is much less electronegative than carbon).
This makes the carbon act as a strong nucleophile, readily attacking electron-deficient centers.
This statement is correct.

Option (B) **Forms new carbon-carbon bond:** Grignard reagents are widely used in organic synthesis to form new carbon-carbon bonds.
The nucleophilic carbon of the Grignard reagent attacks electrophilic carbons, such as those in carbonyl groups or alkyl halides, leading to the formation of a new C-C bond.
This statement is correct.

Option (C) **Reacts with carbonyl compounds:** Grignard reagents react readily with carbonyl compounds (aldehydes, ketones, esters, etc.
) via nucleophilic addition to the electrophilic carbon of the carbonyl group, followed by protonation to yield alcohols.
This is a fundamental reaction in organic synthesis.
This statement is correct.

Option (D) **It is an organomanganese compound:** A Grignard reagent contains a carbon-magnesium bond (\( C-Mg \)).
Therefore, it is an organomagnesium compound, not an organomanganese compound.
Organomanganese compounds exist and have their own applications in organic synthesis, but they are not Grignard reagents.
This statement is incorrect.
Thus, the statement that is not correct about Grignard reagent is that it is an organomanganese compound.