Formation of Salicylic acid from phenol (Kolbe's reaction) is an example of

Options

A. Electrophilic addition reaction
B. Nucleophilic addition reaction
C. Electrophilic substitution reaction
D. Nucleophilic substitution reaction

Answer

To determine the type of reaction involved in the formation of salicylic acid from phenol through Kolbe's reaction, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding the Reactants**:
- The primary reactant is phenol (C6H5OH).
- The other reactants involved in Kolbe's reaction are sodium hydroxide (NaOH) and carbon dioxide (CO2).

2. **Reaction Conditions**:
- The phenol is first treated with sodium hydroxide, which deprotonates the phenol to form phenoxide ion (C6H5O^-).
- This phenoxide ion then reacts with carbon dioxide under high temperature and pressure.

3. **Formation of Salicylic Acid**:
- The phenoxide ion reacts with carbon dioxide to form salicylic acid (C7H6O3) through a carboxylation process.
- The reaction can be summarized as:
\[ C6H5O^- + CO2 \rightarrow C7H6O3 \]

4. **Identifying the Reaction Type**:
- Kolbe's reaction is a type of carboxylation reaction where an aromatic compound (in this case, phenol) is converted into a carboxylic acid (salicylic acid) by the introduction of a carboxyl group (-COOH).
- This reaction is also an example of an electrophilic aromatic substitution since the phenoxide ion acts as a nucleophile and substitutes a hydrogen atom on the aromatic ring with a carboxyl group.

### Conclusion:
The formation of salicylic acid from phenol in Kolbe's reaction is an example of a carboxylation reaction.

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