REIMER-TIEMANN REACTION

Options

A. `CH_(3)`Cl
B. `CH_(2)`
C. `C Cl_(2)`
D. `CO_(2)`

Explanation

### Step-by-Step Solution for Reimer-Tiemann Reaction

1. **Understanding the Reaction**:
The Reimer-Tiemann reaction is a chemical reaction that involves the ortho-formylation of phenols. This means that when phenol is treated with chloroform in the presence of a strong base, it produces ortho- and para-hydroxybenzaldehyde.

2. **Reactants**:
- **Phenol**: The structure of phenol is a benzene ring with a hydroxyl group (-OH) attached.
- **Chloroform**: The chemical formula for chloroform is CHCl3.

3. **Reaction Conditions**:
The reaction is typically carried out in the presence of sodium hydroxide (NaOH) as a base and at elevated temperatures, specifically around 340 Kelvin.

4. **Reaction Mechanism**:
- The hydroxide ion from NaOH deprotonates the phenol, generating a phenoxide ion.
- The phenoxide ion then reacts with chloroform (CHCl3) to form an intermediate.
- This intermediate undergoes rearrangement to yield the final products: ortho-hydroxybenzaldehyde (salicylaldehyde) and para-hydroxybenzaldehyde.

5. **Products**:
- The major product is ortho-hydroxybenzaldehyde (salicylaldehyde), which has both the hydroxyl (-OH) and aldehyde (-CHO) groups on adjacent carbons of the benzene ring.
- The minor product is para-hydroxybenzaldehyde, where the two functional groups are on opposite sides of the benzene ring.

6. **Reason for Major Product**:
The ortho product is favored due to the possibility of intramolecular hydrogen bonding between the hydroxyl group and the aldehyde group in salicylaldehyde, which stabilizes the molecule.

7. **Conclusion**:
Based on the reactants and conditions of the Reimer-Tiemann reaction, the correct answer to the question regarding the reagent used in this reaction is chloroform (CHCl3).

### Final Answer:
The reagent used in the Reimer-Tiemann reaction is **CHCl3 (chloroform)**.

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