`A underset( 0^@C ) overset( NaNO_2 //HCI ) to B underset( 373 K ) overset( H_2 O) to C underset( HBF_4 ) overset(CH_2 N_2)to ` Anisole [A] is :

Options

A. Benzene
B. Anisole
C. aniline
D. phenetole

Answer

To solve the question, we need to identify the reactant A that leads to the final product, anisole, through the given reaction sequence. Let's break down the steps:

### Step 1: Identify the final product
The final product given is anisole, which has the structure of a benzene ring with a methoxy group (-OCH₃) attached to it.

### Step 2: Analyze the reagents and conditions
The first reagent mentioned is NaNO₂ in the presence of HCl at 0°C. This combination is typically used for the diazotization of primary amines.

### Step 3: Determine the structure of reactant A
Since the first step involves diazotization, reactant A must be a primary amine that contains a benzene ring. The simplest primary amine that fits this description is aniline (C₆H₅NH₂), which has a benzene ring and an amino group (-NH₂).

### Step 4: Reaction of A to form B
When aniline (A) reacts with NaNO₂ and HCl, it undergoes diazotization to form benzene diazonium chloride (B).

### Step 5: Conversion of B to C
The next step involves heating benzene diazonium chloride (B) with water at 373 K. This reaction leads to the formation of phenol (C).

### Step 6: Methylation of C to form the final product
Finally, phenol (C) reacts with CH₂N₂ in the presence of HBF₄, which is a methylating agent. This reaction replaces one of the hydrogen atoms on the phenol with a methyl group, resulting in the formation of anisole.

### Conclusion
Thus, the reactant A is aniline (C₆H₅NH₂).

### Answer
**A is Aniline (C₆H₅NH₂)**.

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