Write the reaction involved in the following:
Kolbe's reaction
Kolbe's reaction
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Solution and Explanation
Kolbe's reaction introduces a \(-COOH\) group at the ortho position of phenol through its phenoxide ion reacting with carbon dioxide.
Step 1:
Phenol is first converted to sodium phenoxide with \(NaOH\). The phenoxide ion is more reactive than phenol towards electrophilic substitution.
Step 2:
Sodium phenoxide is treated with carbon dioxide under pressure (about 400 K, 4-7 atm); \(CO_2\) acts as the electrophile and adds at the ortho position. On acidification, salicylic acid is obtained.
Answer: \(C_6H_5ONa + CO_2 \xrightarrow{400\ K,\ pressure}\) sodium salicylate \(\xrightarrow{H^+}\) salicylic acid (2-hydroxybenzoic acid). The product is \(o\text{-}HO\text{-}C_6H_4\text{-}COOH\).
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