Question

The correct order of acidic strength of the major products formed in the given reactions is: 

• A. C>B>A>D
• B. C>B>A>D
• C. A>D>C>B
• D. A>D>B>C

Hint:

For comparing acidic strengths: - Mineral acids (\(\ce{H2CO3}\)) are stronger than organic acids. - Aliphatic carboxylic acids are stronger than aromatic carboxylic acids. - Substituents near the \(\ce{COOH}\) group affect acidity via inductive and resonance effects.

Answer 1

The Correct Option is A

To determine the correct order of acidic strength of the major products formed in the given reactions, let's analyze each reaction step-by-step:

1. Reaction A:
   • The reaction involves the conversion of aniline (PhNH₂) to a nitrile, and then to a carboxylic acid.
   • Final product: Benzoic acid.
2. Reaction B:
   • This is an oxidation of aldehyde to carboxylic acid using Tollen's reagent.
   • Final product: Propanoic acid.
3. Reaction C:
   • Methane oxidation to methanoic acid (formic acid) via the series of reactions.
   • Final product: Formic acid.
4. Reaction D:
   • Grignard reagent reacting with CO₂ forms a carboxylic acid.
   • Final product: Phenylacetic acid.

Now, let's compare the acidic strengths of the carboxylic acids formed:

• Formic acid (C): It is the simplest carboxylic acid with strong acidic strength due to the absence of electron-donating groups.
• Propanoic acid (B): Slightly weaker than formic acid due to the presence of an alkyl group, which is electron-donating.
• Benzoic acid (A): Weaker than propanoic acid as the resonance in the benzene ring reduces its acidity.
• Phenylacetic acid (D): Weaker than benzoic acid, as the alkyl group significantly decreases acidity.

Thus, the order of acidic strength is: C > B > A > D.