Which one of the following reacts with 2,4-dinitro phenyl hydrazine?

Options

A.
B.
C.
D. All of these

Answer

To determine which of the following compounds reacts with 2,4-dinitrophenyl hydrazine (commonly known as Brady's reagent), we need to understand the types of compounds that typically react with this reagent.

### Step-by-Step Solution:

1. **Identify the Reactivity of Brady's Reagent**:
- 2,4-dinitrophenyl hydrazine reacts primarily with aldehydes and ketones. It forms a hydrazone derivative when it reacts with these compounds.

2. **Examine the Given Compounds**:
- Let's consider the compounds mentioned in the question:
- **Aldehydes**: These are organic compounds containing a carbonyl group (C=O) with at least one hydrogen atom attached to the carbonyl carbon.
- **Ketones**: These are organic compounds that contain a carbonyl group (C=O) with two carbon atoms attached to the carbonyl carbon.

3. **Identify Specific Examples**:
- If the question provides specific examples such as acetone (a ketone), ethanol (an aldehyde), and methanol (not typically reactive), we can analyze their structures:
- **Acetone (propanone)**: CH3COCH3 - This is a ketone and will react with Brady's reagent.
- **Ethanol (ethanal)**: CH3CHO - This is an aldehyde and will also react with Brady's reagent.
- **Methanol (not an aldehyde or ketone)**: CH3OH - This is an alcohol and does not react with Brady's reagent.

4. **Conclusion**:
- Since both aldehydes and ketones react with 2,4-dinitrophenyl hydrazine, and if the options include both types of compounds, the answer would be that all of them react with Brady's reagent. Therefore, if the options include acetone (ketone) and ethanol (aldehyde), the correct answer is that all of these compounds react with 2,4-dinitrophenyl hydrazine.

5. **Final Answer**:
- The answer to the question is **option D: all of these**.