When aniline is treated with fuming sulphuric acid at 475 K, it gives

Options

A. sulphanilic acid
B. aniline sulphate
C. o - aminobenzensulphonic acid
D. m - aminobenzensulphonic acid

Answer

To solve the question of what product is formed when aniline is treated with fuming sulfuric acid at 475 K, we can follow these steps:

### Step 1: Understand the Reactants
Aniline (C6H5NH2) is an aromatic amine, which is a basic compound due to the presence of the amino group (-NH2). Fuming sulfuric acid is a strong acid that contains a high concentration of sulfuric acid (H2SO4) and can also contain sulfur trioxide (SO3).

**Hint:** Identify the nature of the reactants. Aniline is a base, and fuming sulfuric acid is a strong acid.

### Step 2: Reaction of Aniline with Fuming Sulfuric Acid
When aniline reacts with fuming sulfuric acid, it can form a salt due to the protonation of the amino group. The reaction can be represented as:
\[ \text{C}_6\text{H}_5\text{NH}_2 + \text{H}_2\text{SO}_4 \rightarrow \text{C}_6\text{H}_5\text{NH}_3^+ + \text{HSO}_4^- \]
This forms anilinium sulfate.

**Hint:** Consider the acid-base reaction where aniline acts as a base and forms a salt with sulfuric acid.

### Step 3: Heating the Reaction Mixture
When the anilinium sulfate is heated at 475 K, a dehydration reaction occurs, leading to the loss of a water molecule. This results in the formation of sulfanilic acid (C6H4(NH2)(SO3H)), which is the product of sulfonation of aniline.

**Hint:** Remember that heating can lead to dehydration, which can change the structure of the compound formed.

### Step 4: Identify the Product
The product formed from the reaction is sulfanilic acid, which is an amino acid with a sulfonic acid group. The structure can be represented as:
\[ \text{C}_6\text{H}_4\text{(NH}_2\text{)(SO}_3\text{H)} \]

**Hint:** Look for the final structure that includes both the amino group and the sulfonic acid group.

### Conclusion
When aniline is treated with fuming sulfuric acid at 475 K, the product formed is sulfanilic acid.

**Final Answer:** Sulfanilic acid (Option 1).