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

Options

A. `-COOH`
B. `-CHCl_(2)`
C. `-CHO`
D. `-CH_(2)Cl`

Explanation

To determine the functional group introduced when phenol reacts 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, a base-catalyzed reaction occurs. The hydroxide ion (OH-) from NaOH deprotonates phenol, making it a better nucleophile.

3. **Formation of Carbene**: The chloroform (CHCl3) reacts with the hydroxide ion to form a trichloromethyl anion (CCl3-). This anion undergoes a rearrangement due to intramolecular repulsion, leading to the formation of a dichlorocarbene (CCl2), which is a reactive species.

4. **Nucleophilic Attack**: The dichlorocarbene (CCl2) then reacts with the phenoxide ion (the deprotonated form of phenol) through a nucleophilic attack, resulting in the formation of an intermediate.

5. **Formation of Aldehyde**: The intermediate undergoes rearrangement and elimination to yield the final product, which is an aldehyde. Specifically, this reaction is known as the Riemert-Thiemann reaction, and it produces ortho- or para-hydroxybenzaldehyde (salicylaldehyde).

6. **Identify the Functional Group**: The final product of this reaction is an aldehyde group (-CHO). Therefore, the functional group introduced by the reaction of phenol with chloroform in the presence of dilute sodium hydroxide is the aldehyde functional group.

### Final Answer:
The reaction of phenol with chloroform in the presence of dilute sodium hydroxide finally introduces the aldehyde functional group (-CHO).

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