Question

Write the reaction involved in Kolbe’s reaction.

Hint:

Kolbe's reaction is the industrial method for preparing Salicylic acid, which is used to make Aspirin.

Answer 1

Step 1: Conceptual Overview:
Kolbe's reaction involves the electrophilic substitution of the phenoxide ion by carbon dioxide, leading to the formation of a hydroxy acid. This reaction is commonly used to synthesize salicylic acid, which is the precursor to aspirin.
Step 2: Detailed Explanation:
To begin the reaction, phenol is first converted into sodium phenoxide by reacting phenol with sodium hydroxide (NaOH).
Next, sodium phenoxide undergoes a reaction with carbon dioxide (\( CO_2 \)) under conditions of 400K temperature and 4-7 atm pressure. This reaction leads to the formation of an intermediate compound, sodium salicylate.
The final step involves acidifying the sodium salicylate with a proton source (\( H^+ \)) to yield the desired product, 2-hydroxybenzoic acid, also known as salicylic acid.
The overall chemical equation for Kolbe's reaction is as follows:
\[ C_6H_5O^-Na^+ + CO_2 \xrightarrow{400K, 4-7 atm} \text{o-}HOC_6H_4COONa \xrightarrow{H^+} \text{o-}HOC_6H_4COOH \]
Step 3: Final Conclusion:
The product formed in Kolbe's reaction is salicylic acid, which is an important compound in the pharmaceutical industry.