Question

A chromatography column, packed with silica gel as stationary phase, was used to separate a mixture of compounds consisting of (A) benzanilide (B) aniline and (C) acetophenone. When the column is eluted with a mixture of solvents, hexane : ethylacelate (20:80), the sequence of obtained compounds is :

• A. (A), (B) and (C)
• B. (B), (A) and (C)
• C. (C), (A) and (B)
• D. (B), (C) and (A)

Hint:

In column chromatography on polar silica gel, the less polar (less strongly adsorbed) compound elutes first and the most polar elutes last.

Answer 1

The Correct Option is C

Step 1: Elution order on silica follows increasing adsorption affinity, which parallels increasing polarity/hydrogen-bonding strength: ketone \(\lt\) amide \(\lt\) primary amine.
Step 2: Assign the compounds: (C) acetophenone (ketone), (A) benzanilide (amide), (B) aniline (primary amine).
Step 3: The least adsorbed compound travels with the solvent front and comes out first. So the sequence collected is (C), then (A), then (B).
Answer: (C)