Reaction of phenol with chloroform in presence of dilute sodium hydroxide finally introduces which one of the following functional group ?

Options

A. `-CHCl_(2)`
B. `-CHO`
C. `-CH_(2)Cl`
D. `-CO O H`

Answer

To solve the question regarding the reaction of phenol with chloroform in the presence of dilute sodium hydroxide, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactants in this reaction are phenol (C6H5OH) and chloroform (CHCl3), with dilute sodium hydroxide (NaOH) acting as a base.

2. **Understand the Reaction Mechanism**:
- When phenol reacts with chloroform in the presence of dilute NaOH, it undergoes a specific reaction known as the Riemer-Tiemann reaction.

3. **Formation of Intermediate**:
- The phenol first reacts with chloroform to form an intermediate compound. This involves the formation of a sodium phenoxide (C6H5O^-Na^+) and dichloromethyl anion (CHCl2^-).

4. **Substitution Reaction**:
- The sodium hydroxide present in the solution facilitates the substitution of chlorine atoms in the intermediate. The chlorine atoms are replaced by hydroxyl groups (OH).

5. **Elimination of Water**:
- As the reaction proceeds, one of the hydroxyl groups is eliminated as water (H2O), leading to the formation of an aldehyde group.

6. **Final Product**:
- The final product of this reaction is salicylaldehyde (C6H4(OH)CHO), which contains the aldehyde functional group (CHO).

7. **Conclusion**:
- Therefore, the functional group introduced to phenol through this reaction is the aldehyde group (CHO).

### Final Answer:
The functional group introduced to phenol when it reacts with chloroform in the presence of dilute sodium hydroxide is **CHO (aldehyde group)**.

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