JEE Challenger
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Total Carboxylic Acid Groups in Product P

Determine the total count of carboxylic acid functional groups present in the final product PP obtained from the sequence of reactions shown below:

Question Diagram 1
Official Numerical Answer2

Step-by-Step Solution

To determine the total count of carboxylic acid functional groups present in the final product PP, we analyze the reaction sequence step-by-step:

Step 1: Acidic Hydrolysis and Heating (H3O+,Δ\text{H}_3\text{O}^+, \Delta)

  1. Hydrolysis of the Anhydride: The starting material contains a cyclic anhydride functional group fused to a diketone system. Treatment with hydronium ions (H3O+\text{H}_3\text{O}^+) hydrolyzes the cyclic anhydride ring to give two carboxylic acid functional groups (−COOH-\text{COOH}).

  2. Decarboxylation of β\beta-Keto Acids: In the hydrolyzed intermediate, each newly formed carboxylic acid group is located at a position β\beta to a ketone carbonyl group (C=O\text{C=O}).

    β\beta-keto acids are thermally unstable and readily undergo decarboxylation upon heating (Δ\Delta) via a six-membered cyclic transition state: R−CH(COOH)−C(=O)−R′→ΔR−CH2−C(=O)−R′+CO2↑\text{R}-\text{CH}(\text{COOH})-\text{C}(=\text{O})-\text{R}' \xrightarrow{\Delta} \text{R}-\text{CH}_2-\text{C}(=\text{O})-\text{R}' + \text{CO}_2\uparrow

    Since both −COOH-\text{COOH} groups are β\beta to ketone carbonyls, heating causes both carboxylic acid groups to be lost as two molecules of CO2\text{CO}_2. Thus, after Step 1, no carboxylic acid functional groups remain in the intermediate diketone.


Steps 2 & 3: Oxidative Ozonolysis (O3\text{O}_3 followed by H2O2\text{H}_2\text{O}_2)

  1. Cleavage of the Alkene Double Bond: The intermediate obtained from Step 1 contains one carbon-carbon double bond (C=C\text{C=C}) within its cyclohexene ring.

  2. Oxidation to Carboxylic Acids: Reaction with ozone (O3\text{O}_3) followed by oxidative workup with hydrogen peroxide (H2O2\text{H}_2\text{O}_2) oxidatively cleaves the C=C\text{C=C} double bond. Each CH\text{CH} carbon of the double bond is oxidized to a carboxylic acid group (−COOH-\text{COOH}): R−CH=CH−R′→2. H2O21. O3R−COOH+HOOC−R′\text{R}-\text{CH}=\text{CH}-\text{R}' \xrightarrow[2.\ \text{H}_2\text{O}_2]{1.\ \text{O}_3} \text{R}-\text{COOH} + \text{HOOC}-\text{R}'

  3. The ketone carbonyl groups present in the bicyclic core remain unreactive under these conditions.


Conclusion

The oxidative ozonolysis of the single double bond in the cyclohexene ring yields a open-chain dicarboxylic acid derivative containing exactly 22 carboxylic acid groups (−COOH-\text{COOH}).

Therefore, the total count of carboxylic acid functional groups present in product PP is 2.