Question

Conversion of phenol to salicylic acid and to salicyaldehyde are known as? (respectively)
(A) Reimer-Tiemann reaction and Kolbe’s reaction
(B) Williamson’s synthesis and Hydroboration-oxidation
(C) Kolbe’s reaction and Williamson’s synthesis
(D) Kolbe’s reaction and Reimer-Tiemann reaction

Answer 1

Hint:The conversion of phenol to salicylic acid takes place through a base, and hydrolysis. If we talk about the conversion of phenol of salicylaldehyde takes place through the action of chloroform. So, we identify the naming reactions in which these conversions take place.

Complete step by step solution:
First, we will discuss the conversion of phenol to salicylic acid.
The phenol will be deprotonated by strong base i.e. hydroxide ion. There will be addition of phenoxide ions formed to the carbon-dioxide.
So, we can say that the addition further leads to the carboxylate formation. Then, it will further lead to the formation of carboxylic acid, i.e. salicylic acid.
The chemical reaction is

Thus, we know this whole mechanism takes place in Kolbe’s reaction, it is used for the synthesis of aspirin also known as salicylic acid in the industries.
Now, the next we have conversion of phenol to salicylaldehyde. It was proposed by Karl Riemer, mainly used for the ortho- phenols.
In this reaction too like Kolbe’s reaction, there is deprotonation of chloroform by strong base like KOH.
This reaction takes place through the nucleophilic attack, and the basic hydrolysis is done, leading to the formation of salicylaldehyde.
The chemical reaction is

Thus, we can say this whole mechanism takes place in the Riemer –Tiemann reaction.
In the last, we can conclude that conversion of phenol to salicylic acid and to salicylaldehyde are known as Kolbe’ reaction, and Riemer-Tiemann reaction.
Hence, the correct option is (D).

Note: Don’t get confused between both these reactions. These both takes place through deprotonation by a strong base, as we discussed; but the product formation will be different. In case 1 there is addition of carbon-dioxide, and in case 2 there is nucleophilic attack.