`C_6 H_5 NH_2 underset(0^@ C) overset( NaNO_2 //HCI)to (A) overset(H_3 PO_2 // H_2 O ) to (B ) ` the compound (B ) is :

Options

A. `C_(6 ) H_(5 ) OH`
B. `C_6 H_5 CH_2 OH`
C. `C_6 H_6`
D. none of these

Answer

To solve the problem, we need to follow the steps of the reaction involving aniline (C₆H₅NH₂) and identify the final product (B) after the reactions with NaNO₂/HCl and H₃PO₂/H₂O.

### Step 1: Identify the starting compound
The starting compound is aniline, which has the molecular formula C₆H₅NH₂. It consists of a benzene ring (C₆H₅) with an amino group (NH₂) attached to it.

### Step 2: Diazotization of aniline
When aniline reacts with sodium nitrite (NaNO₂) in the presence of hydrochloric acid (HCl) at 0°C, it undergoes diazotization. The amino group (NH₂) is converted into a diazonium group (N₂⁺) resulting in the formation of benzene diazonium chloride (C₆H₅N₂Cl). The reaction can be summarized as follows:

\[ \text{C}_6\text{H}_5\text{NH}_2 + \text{NaNO}_2 + \text{HCl} \rightarrow \text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^- + \text{NaCl} + \text{H}_2\text{O} \]

### Step 3: Reduction of benzene diazonium chloride
Next, the benzene diazonium chloride (C₆H₅N₂Cl) is treated with phosphinic acid (H₃PO₂) and water (H₂O). This step involves the reduction of the diazonium salt. The nitrogen gas (N₂) is released, and the diazonium group is replaced by a hydrogen atom, leading to the formation of benzene (C₆H₆). The reaction can be summarized as follows:

\[ \text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^- + \text{H}_3\text{PO}_2 + \text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_6 + \text{N}_2 + \text{HCl} + \text{H}_3\text{PO}_3 \]

### Step 4: Identify the final product (B)
The final product (B) after the reduction of benzene diazonium chloride is benzene (C₆H₆).

### Conclusion
Thus, the compound (B) is benzene (C₆H₆).

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