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JEE Advanced · Chemistry · 27. Carboxylic Acids

In the following reactions, P,Q,R, and S are the major products.




The correct statement(s) about P,Q,R, and S is(are)

  1. A P and Q are monomers of polymers dacron and glyptal, respectively.
  2. B P, Q, and R are dicarboxylic acids.
  3. C Compounds Q and R are the same.
  4. D R does not undergo aldol condensation and S does not undergo Cannizzaro reaction.
Verified Solution

Answer & Solution

Correct Answer

(D) R does not undergo aldol condensation and S does not undergo Cannizzaro reaction.

Step-by-step Solution

Detailed explanation

Toluene part of the reactant in the first reactionundergoes oxidation with KMnO4, forms benzoic acid. In this conversion, alkyl part of toluene converts into carboxylic group. So, P is a monocarboxylic acid.

Both ester and acid halides undergo hydrolysis to give carboxylic acid. Hence, the product Q is the dicarboxylic acid. And it is known as isophthalic acid.

In the third reaction, ester undergo hydrolysis in the first step, which results beta keto acid. Beta keto acids are unstable. They liberate carbon dioxide on heating. The alpha methyl ketone formed undergo oxidation with chromic acid give carboxylic acid. Hence, R is also isophthalic acid.

In the fourth reaction, the bromo part reacts with magnesium metal to give Grignard reagent. Grignard reagent give carboxylic acid upon reaction with carbon dioxide. Now during the hydrolysis of previous step acetal cleavage takes place and gives aldehyde functional group. This aldehyde converts to carboxylic acid with Tollen's reagent. This results the terephthalic acid.

The products RandS are dicarboxylic acids and does not undergo Aldol condensation reaction or Cannizzaro's reaction.
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