Concept:Grignard reagents (\( \text{RMgX} \)) are potent nucleophiles that attack the electrophilic carbon atom in carbon dioxide (\( \text{O=C=O} \)).
Formula:$$ \text{R-MgX} + \text{CO}_2 \xrightarrow{\text{dry ether}} \text{R-COO}^-\text{MgX}^+ \xrightarrow{\text{H}_3\text{O}^+} \text{R-COOH} $$
Solution:- The nucleophilic alkyl group (\( \text{R}^- \)) from the Grignard reagent attacks the partially positive central carbon of \( \text{CO}_2 \).
- This pushes electrons onto one of the oxygens, forming a carboxylate magnesium salt intermediate.
- Upon acidic workup (hydrolysis), the salt is protonated to yield a carboxylic acid with one more carbon atom than the original Grignard reagent.
Why other options are incorrect:Aldehydes and ketones are formed by reacting Grignard reagents with formates or nitriles, respectively. Ethers are often the solvent, not the product.
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