Question

Phenol reacts with chloroform in presence of aqueous sodium hydroxide to give chief product:

• A. 2-Chloro Benzaldehyde
• B. 2-Hydroxy Benzaldehyde
• C. 2-Hydroxy Benzaldehyde
• D. 3-Chloro Benzaldehyde

Answer 1

The Correct Option is B

To determine the chief product when phenol reacts with chloroform in the presence of aqueous sodium hydroxide, we need to consider the Reimer-Tiemann reaction. This is an organic transformation used primarily to form ortho-hydroxybenzaldehydes from phenols. 

1. The reaction involves the reaction of phenol (\(\text{C}_6\text{H}_5\text{OH}\)) with chloroform (\(\text{CHCl}_3\)) in the presence of aqueous sodium hydroxide (\(\text{NaOH}\)).
2. In the Reimer-Tiemann reaction, the chloroform serves as a methylene transfer agent, and the base, NaOH, generates the dichlorocarbene intermediate (\(\text{CCl}_2\)), which facilitates the ortho-formylation of phenol.
3. The mechanism involves the following key steps:
   • Formation of dichlorocarbene intermediate from chloroform and NaOH.
   • Electrophilic attack of the \(\text{CCl}_2\) intermediate on the ortho position of phenol.
   • Hydrolysis of the resulting intermediate to form 2-Hydroxy Benzaldehyde, also known as salicylaldehyde.
4. Thus, the chief product of this reaction is 2-Hydroxy Benzaldehyde.

Now let's evaluate the options:

• 2-Chloro Benzaldehyde: Incorrect, as the reaction does not introduce a chloro group but rather adds a formyl group.
• 2-Hydroxy Benzaldehyde: Correct, as explained, this is the major product of the Reimer-Tiemann reaction.
• 2-Hydroxy Benzaldehyde: Repeated option, also correct.
• 3-Chloro Benzaldehyde: Incorrect, there is no substitution at the meta position in this reaction.

Therefore, the correct answer is 2-Hydroxy Benzaldehyde.