Carboxylic acid from Grignard Reagent

$$\text{R-MgX} + \text{CO}_2 \xrightarrow{\text{Dry Ether}} \text{R-COOMgX} \xrightarrow{\text{H}_3\text{O}^+} \text{R-COOH}$$

Concept: Carbonylation of a strong organometallic nucleophile through step-wise addition onto carbon dioxide (acting as dry ice). This synthetic path provides an effective method for stepping up a homologous series by adding exactly one new carbon atom to the parent alkyl framework.

Notation:

• $$\text{CO}_2$$ = Solid dry ice electrophile;
• $$\text{Dry Ether}$$ = Mandatory aprotic solvent required to prevent the destructive self-protonation of the highly basic Grignard reagent.