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 : ethyl acetate (20 : 80), the sequence of obtained compounds is

Options

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

Answer

To solve the problem of determining the sequence of compounds eluted from a chromatography column packed with silica gel and using a solvent mixture of hexane and ethyl acetate (20:80), we need to analyze the polarity of the compounds involved. The compounds in the mixture are:

- A: Benzanilide
- B: Aniline
- C: Acetophenone

### Step-by-Step Solution:

1. **Identify the Polarity of Each Compound:**
- **Benzanilide (A)**: Contains both an amine and a carbonyl group, making it moderately polar.
- **Aniline (B)**: Contains an amine group, which is polar due to the presence of the nitrogen atom, but it has a less polar character compared to compounds with carbonyl groups.
- **Acetophenone (C)**: Contains a carbonyl group (C=O), which is highly polar, making acetophenone the most polar compound among the three.

2. **Understand the Solvent System:**
- The solvent mixture is 20% hexane (non-polar) and 80% ethyl acetate (polar). This means the elution will favor the more polar compounds first due to the higher proportion of the polar solvent.

3. **Determine the Elution Order:**
- Since acetophenone is the most polar compound, it will interact more strongly with the polar ethyl acetate and will be eluted first.
- Next, benzanilide, being moderately polar, will be eluted after acetophenone.
- Finally, aniline, which is less polar than both acetophenone and benzanilide, will be eluted last.

4. **Write the Sequence of Elution:**
- Based on the analysis, the order of elution from the chromatography column will be:
- First: Acetophenone (C)
- Second: Benzanilide (A)
- Third: Aniline (B)

Thus, the sequence of obtained compounds is **C (Acetophenone), A (Benzanilide), B (Aniline)**.

### Final Answer:
The correct sequence of compounds obtained from the chromatography column is C, A, B.