An organic compound A having molecular formula C₆H₆O gives a violet colour with neutral FeCl₃ ​ solution. A on treatment with CO₂​ and NaOH at 400 K under pressure gives B which on acidification gives a compound C. The compound C reacts with acetyl chloride to give D which is popular pain killer. Deduce the structure of A, B, C and D.

What is the name of compound C?

Salicylic acid

The correct answer is option 4. Salicylic acid.

To deduce the structures of compounds A, B, C, and D, let us follow the clues given in the problem:

Compound A (\(C_6H_6O)\) gives a violet color with neutral \(FeCl_3\) solution.

This indicates that compound A is a phenol because phenols typically give a violet color with neutral \(FeCl_3\). Therefore, A is likely to be phenol \((C_6H_5OH)\).

\(A\) on treatment with \(CO_2\) and \(NaOH\) at 400 K under pressure gives \(B\) which on acidification gives a compound \(C\)

This reaction is characteristic of the Kolbe-Schmitt reaction, where phenol reacts with CO₂ and NaOH to form sodium salicylate (B), which upon acidification gives salicylic acid (C).

Compound \(C\) reacts with acetyl chloride to give \(D\) which is a popular pain killer

Salicylic acid (C) reacts with acetyl chloride to form acetylsalicylic acid (D), commonly known as aspirin, which is a popular painkiller.