Chemical Reactions Of Aldehydes Ketones And Carboxylic Acids

The reaction sequence provided involves the following steps: 

• First, the reaction of a carboxylic acid with red phosphorus and bromine.
• Then the reaction of the product with NaOH and followed by hydrolysis.

Step 1: Understanding the Reaction

The starting compound is a carboxylic acid (CH₃COOH). The reaction with red phosphorus and bromine results in the formation of an acyl bromide intermediate. This intermediate undergoes hydrolysis to form a product, denoted as . The next part of the reaction sequence involves treating with concentrated solution followed by acidification to yield the product , which is likely a compound such as an amide or a derivative of the starting acid.

Step 2: Analyzing the Statements

Option A: "P can be reduced to a primary alcohol using NaBH₄."

This statement is incorrect. (which is likely an acyl derivative) cannot be reduced to a primary alcohol using sodium borohydride (NaBH₄). NaBH₄ is effective in reducing aldehydes and ketones but not carboxylic acids or their derivatives.

Option B: "Treating P with concentrated NH₄OH solution followed by acidification gives Q."

This statement is correct. Treating acyl derivatives with ammonium hydroxide followed by acidification typically yields the corresponding amide or a related compound. This reaction is common in organic synthesis.

Option C: "Treating Q with a solution of NaNO₂ in aqueous HCl liberates N₂."

This statement is correct. The reaction of an amide (or a similar compound) with sodium nitrite (NaNO₂) in acidic conditions (HCl) results in the formation of nitrogen gas (N₂) due to the diazotization process.

Option D: "P is more acidic than CH₃CH₂COOH."

This statement is correct. , being an acyl derivative, is more acidic than propanoic acid (CH₃CH₂COOH) because the acyl group (RCO-) enhances the ability to donate a proton (H⁺) compared to a simple carboxyl group.

Final Answer:

The correct options are: B, C, and D.