`underset((A)) (EtCOOMe) overset("(i)" NH_2 NH_2 "(ii)" HNO_2) underset("(iii)" overset (Ө) OH "(iv)" H_3 O^(oplus))rarr(B)`
The product `(B)` is :

Options

A. `MeNH_2`
B. `EtNH_2`
C. `MeCONH_2`
D. `EtCONHMe`

Explanation

To solve the given problem, we will go through the reactions step by step.

### Step 1: Identify the starting compound (A)
The starting compound is Ethyl Methyl Carboxylate (EtCOOMe), which can be represented as:
- Ethyl group (Et) = C2H5
- Methyl group (Me) = CH3
Thus, the structure can be written as:
\[ \text{EtCOOMe} \equiv \text{C}_2\text{H}_5\text{COOCH}_3 \]

### Step 2: Reaction with Hydrazine (NH2NH2)
When Ethyl Methyl Carboxylate reacts with hydrazine (NH2NH2), it undergoes a nucleophilic substitution where the hydrazine replaces the methoxy group (OMe):
\[ \text{EtCOOMe} + \text{NH}_2\text{NH}_2 \rightarrow \text{EtCOONHNH}_2 \]
This gives us Ethyl Hydrazone:
\[ \text{EtCOONHNH}_2 \]

### Step 3: Reaction with Nitrous Acid (HNO2)
The next step involves the reaction with nitrous acid (HNO2), which converts the hydrazine group (NH2) to a hydroxyl group (OH):
\[ \text{EtCOONHNH}_2 + \text{HNO}_2 \rightarrow \text{EtCOONH}_2\text{OH} \]
This results in the formation of an intermediate compound with a hydroxyl group:
\[ \text{EtCOONH}_2\text{OH} \]

### Step 4: Reaction with Hydroxide Ion (OH-)
The intermediate compound then reacts with hydroxide ion (OH-), leading to the loss of a water molecule:
\[ \text{EtCOONH}_2\text{OH} + \text{OH}^- \rightarrow \text{EtCOONH} \]
This results in the formation of a compound with an amine group:
\[ \text{EtCOONH} \]

### Step 5: Rearrangement (Lossen Rearrangement)
The next step involves a rearrangement known as Lossen rearrangement, where the ethyl group migrates to the nitrogen:
\[ \text{EtCOONH} \rightarrow \text{EtNCO} \]
This gives us an isocyanate:
\[ \text{EtNCO} \]

### Step 6: Reaction with Hydronium Ion (H3O+)
Finally, when the isocyanate reacts with hydronium ion (H3O+), it hydrolyzes to form an amine:
\[ \text{EtNCO} + \text{H}_3\text{O}^+ \rightarrow \text{EtNH}_2 + \text{CO}_2 \]
This results in the formation of Ethylamine (EtNH2) and carbon dioxide (CO2).

### Final Product (B)
The final product (B) is:
\[ \text{EtNH}_2 \]

### Summary of Steps:
1. **Identify starting compound (A)**: Ethyl Methyl Carboxylate (EtCOOMe).
2. **React with hydrazine (NH2NH2)**: Forms Ethyl Hydrazone (EtCOONHNH2).
3. **React with nitrous acid (HNO2)**: Converts NH2 to OH, forming (EtCOONH2OH).
4. **React with hydroxide ion (OH-)**: Leads to loss of water, forming (EtCOONH).
5. **Undergo Lossen rearrangement**: Ethyl group migrates to nitrogen, forming (EtNCO).
6. **React with hydronium ion (H3O+)**: Hydrolyzes to form Ethylamine (EtNH2) and CO2.