During reduction of aldehydes with hydrazine and potassium hydroxide, the first is the formation of

Options

A. `R-CH=N-NH_(2)`
B. `R-C-=N`
C. `R-underset(O)underset(||)(C)-NH_(2)`
D. `R-CH=NH`

Explanation

To solve the question regarding the reduction of aldehydes with hydrazine and potassium hydroxide, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- We have an aldehyde, which can be represented as \( RCHO \), where \( R \) is an alkyl group.
- The reducing agent is hydrazine, which has the formula \( NH_2NH_2 \).

2. **Reaction Setup**:
- The reaction occurs in the presence of potassium hydroxide (KOH), which acts as a base.

3. **Formation of Aldehyde Hydrazone**:
- When the aldehyde reacts with hydrazine, the carbonyl group (C=O) of the aldehyde reacts with the hydrazine.
- The reaction involves the nucleophilic attack of the hydrazine on the carbonyl carbon, leading to the formation of a tetrahedral intermediate.

4. **Elimination of Water**:
- The tetrahedral intermediate then loses a molecule of water (H2O) through a condensation reaction.
- This results in the formation of a double bond between the carbon of the aldehyde and the nitrogen of the hydrazine.

5. **Product Formation**:
- The final product of this reaction is an aldehyde hydrazone, which can be represented as \( RCH=NH_2 \).
- The structure includes the alkyl group \( R \), a carbon atom double-bonded to nitrogen, and an amino group (\( NH_2 \)).

6. **Conclusion**:
- The product formed from the reduction of an aldehyde with hydrazine in the presence of potassium hydroxide is called an aldehyde hydrazone.

### Final Answer:
The first product formed during the reduction of aldehydes with hydrazine and potassium hydroxide is an **aldehyde hydrazone**.

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