identify B in the following reaction
`CH_(3) - CN overset(Na+ alcohol) (to) A overset( HNO_(2))(to) (B)`

Options

A. Ethanol
B. Ethanal
C. Acetic acid
D. Ethyl chloride

Answer

To identify compound B in the given reaction sequence, we will analyze the steps involved.

### Step-by-Step Solution:

1. **Identify the Starting Material**:
The starting material is methyl cyanide (CH₃CN), which is a nitrile.

2. **Reaction with Sodium Alcohol**:
When methyl cyanide reacts with sodium in the presence of alcohol, it acts as a strong reducing agent. This reaction reduces the nitrile group (–CN) to an amine group (–NH₂).
- The reaction can be represented as:
\[ \text{CH}_3\text{CN} \overset{\text{Na + alcohol}}{\rightarrow} \text{CH}_3\text{CH}_2\text{NH}_2 \quad \text{(A)} \]
Here, A is ethylamine (CH₃CH₂NH₂).

3. **Reaction with HNO₂**:
The next step involves the reaction of ethylamine (A) with nitrous acid (HNO₂). This reaction is known as diazotization, where the amine group is converted into a diazonium salt.
- The reaction can be represented as:
\[ \text{CH}_3\text{CH}_2\text{NH}_2 \overset{\text{HNO}_2}{\rightarrow} \text{CH}_3\text{CH}_2\text{N}_2^+ \text{Cl}^- \quad \text{(intermediate)} \]
This intermediate is ethyl diazonium chloride.

4. **Hydrolysis of Diazotization Product**:
The diazonium salt is unstable and readily hydrolyzes in the presence of moisture (water) to form an alcohol.
- The hydrolysis can be represented as:
\[ \text{CH}_3\text{CH}_2\text{N}_2^+ \text{Cl}^- + \text{H}_2\text{O} \rightarrow \text{CH}_3\text{CH}_2\text{OH} + \text{N}_2 \quad \text{(B)} \]
Thus, the final product B is ethanol (CH₃CH₂OH).

### Final Answer:
B is ethanol (CH₃CH₂OH).

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