An organic compound A has molecular formula `C_7H_9N` and it forms a clear solution when dissolved in aqueous `KOH` solution of benzene sulphonyl chloride. A on treatment with `NaNO_2` and `HCl` at `0^@` C and then with 2-naphthol form an intensely coloured compound. Aslo A on treatment with `CH_3COCl` followed by electrophilic sustitution yields a single product. identify. A

Options

A. 4-emthylaniline
B. 2-methylaniline
C. 3-methylaniline
D. N-methylaniline

Explanation

To solve the problem, we will follow a systematic approach based on the information provided in the question.

### Step 1: Analyze the Molecular Formula
The organic compound A has the molecular formula \( C_7H_9N \). This indicates that it contains 7 carbon atoms, 9 hydrogen atoms, and 1 nitrogen atom.

**Hint**: Look for structural features that can be derived from the molecular formula, such as the presence of functional groups.

### Step 2: Reaction with Benzene Sulphonyl Chloride
The compound A forms a clear solution when dissolved in an aqueous KOH solution and treated with benzene sulphonyl chloride. This reaction is characteristic of primary amines, which react to form sulphonamides.

**Hint**: Recall that primary amines will react with benzene sulphonyl chloride to form a clear solution, while secondary and tertiary amines will not.

### Step 3: Identify Possible Structures
Given that A is a primary amine and has the formula \( C_7H_9N \), the possible structure could be an aromatic amine. The simplest aromatic amine with this formula is aniline (C6H5NH2). The presence of a methyl group suggests that we are dealing with a substituted aniline.

**Hint**: Consider the position of the methyl group on the aromatic ring (ortho, meta, or para).

### Step 4: Reaction with NaNO2 and HCl
When A is treated with NaNO2 and HCl at 0°C, it forms a diazonium salt. The subsequent reaction with 2-naphthol produces an intensely colored compound, which indicates the formation of a coupling product.

**Hint**: The coupling reaction with 2-naphthol suggests that the amine is likely para-substituted, as this leads to stable colored products.

### Step 5: Electrophilic Substitution with CH3COCl
The treatment of A with acetyl chloride (CH3COCl) followed by electrophilic substitution yields a single product. This indicates that the methyl group is likely in a position that allows for only one substitution product.

**Hint**: The presence of the methyl group on the aromatic ring can influence the position of electrophilic substitution.

### Step 6: Determine the Structure of A
Considering the above points, the most likely structure for A is 4-methyl aniline (p-toluidine), where the methyl group is in the para position relative to the amino group.

**Hint**: Verify the structure by checking if it fits all the reactions described in the problem.

### Conclusion
Based on the analysis, the organic compound A is identified as **4-methyl aniline** (p-toluidine).

### Summary of Steps
1. Analyze the molecular formula \( C_7H_9N \).
2. Recognize the reaction with benzene sulphonyl chloride indicates a primary amine.
3. Consider the structure of substituted aniline.
4. Understand the formation of a diazonium salt and its reaction with 2-naphthol.
5. Evaluate the electrophilic substitution with CH3COCl leading to a single product.
6. Conclude that A is 4-methyl aniline.