2,4 - DNP is obtained by reacting hydrazine hydrate with which of the following ?

Options

A.
B.
C.
D.

Answer

To determine which compound reacts with hydrazine hydrate to produce 2,4-dinitrophenylhydrazine (2,4-DNP), we will analyze the options provided and identify the correct precursor compound.

### Step-by-Step Solution:

1. **Understand the Structure of 2,4-DNP**:
- 2,4-DNP is 2,4-dinitrophenylhydrazine. It consists of a phenyl ring with two nitro groups (-NO2) at the 2 and 4 positions and a hydrazine group (-NH-NH2) attached.

2. **Identify the Required Functional Groups**:
- To synthesize 2,4-DNP, we need a compound that has a phenyl ring with nitro groups at the 2 and 4 positions. This compound will react with hydrazine hydrate (H2N-NH2) to form the hydrazone.

3. **Examine the Given Options**:
- We need to evaluate each option to see which one contains the necessary nitro groups in the correct positions.

4. **Evaluate Each Option**:
- **Option A**: Contains a chlorine atom and a nitro group at the ortho position. This will not yield 2,4-DNP as it lacks the nitro group at the para position.
- **Option B**: Contains a chlorine atom with a nitro group at the para position. This is the correct structure as it has nitro groups at both the 2 and 4 positions relative to the hydrazine attachment.
- **Option C**: Contains multiple nitro groups which will lead to a trinitro compound, which is not what we need.
- **Option D**: Similar to option C, it has nitro groups in incorrect positions or too many nitro groups.

5. **Conclusion**:
- The correct precursor compound that reacts with hydrazine hydrate to yield 2,4-DNP is the one that has a nitro group at the para position to the chlorine atom. Thus, **Option B** is the correct answer.

### Final Answer:
The compound that reacts with hydrazine hydrate to form 2,4-DNP is the one with a nitro group at the para position to the chlorine atom.