Which of the following shows haloform reaction?

Options

A. `H_(3)C-underset(O)underset(||)(C)-underset(O)underset(||)(C)-OH`
B. `H_(3)C-underset(OH)underset(|)(C)H-underset(O)underset(||)(C)-OH`
C. `H_(3)C-underset(O)underset(||)(C)-CH_(2)CH_(3)`
D. all of the above

Answer

To determine which of the given compounds shows a haloform reaction, we need to understand the criteria for a compound to undergo this reaction.

### Step-by-Step Solution:

1. **Understand the Haloform Reaction**:
The haloform reaction occurs with compounds that have a methyl ketone structure (R-CO-CH3) or a secondary alcohol that can be oxidized to a methyl ketone. The general reaction involves the halogen (X2) and sodium hydroxide (NaOH), leading to the formation of a haloform (CHX3) and a carboxylate ion.

2. **Identify the Functional Groups**:
- The haloform reaction is specifically indicated by the presence of a methyl ketone (CH3-CO-) or a secondary alcohol (R-CHOH-CH3).
- The general structure for a methyl ketone is R-CO-CH3, where R can be any alkyl group.

3. **Analyze the Given Compounds**:
- **Compound 1**: Contains the methyl ketone group (CH3-C(=O)-R). This will react positively.
- **Compound 2**: Contains a secondary alcohol (CH3-CHOH-R). This can be oxidized to a methyl ketone, thus it will also react positively.
- **Compound 3**: Again contains a methyl ketone group (CH3-C(=O)-R). This will react positively too.

4. **Conclusion**:
Since all three compounds contain either a methyl ketone or a secondary alcohol that can be converted to a methyl ketone, they will all show a positive haloform reaction.

5. **Final Answer**:
Therefore, the correct option is **Option 4: All of the above**.