Question

In the reaction,
\[{{\rm{C}}_{\rm{6}}}{{\rm{H}}_{\rm{5}}}{\rm{OH}} \overset{NaOH}{\rightarrow} (A) \overset{CO_{2}}{\rightarrow} (B)\overset{HCl}{\rightarrow} (C)\], the compound (C) is,
A. Benzoic acid
B. Salicylaldehyde
C. Chlorobenzene
D. Salicylic acid

Answer 1

Hint:/ Kolbe’s reaction is the reaction of phenol with sodium hydroxide and carbon dioxide in an acidic medium. Here, we must understand Kolbe's reaction in detail to identify the product obtained in the given reaction.

Complete step by step answer:
First, we will understand what Kolbe’s reaction is. Kolbe's reaction is the conversion of phenol into salicylic acid. In the first step, phenol is converted into phenoxide ion by reacting it with sodium hydroxide. In the second step, the reaction of phenoxide ions with carbon dioxide gives sodium salicylate. And the reaction of sodium salicylate with HCl gives salicylic acid.


Fig: Kolbe’s reaction

Therefore, the product C obtained is salicylic acid. Hence, option D is right.

Additional Information: Let’s understand another important reaction of phenol, that is, the Riemer-Tiemann reaction. In this reaction, phenol to salicylaldehyde conversion takes place by reacting phenol with chloroform along with sodium hydroxide in the first step. In the second step, the formed intermediate again undergoes a reaction with sodium hydroxide in the acidic medium. The product formed in the reaction is salicylaldehyde.


Fig: Riemer-Tiemann reaction

Note: Salicylic acid has some useful application in our everyday life. It treats acne by reducing redness and swelling. It blocked skin pores to shrink pimples. It is also useful for its application in loosening and softening dry, thickened skin. But frequent uses of salicylic acid may cause skin irritation.