Aniline when treated with `K_2 Cr_2 O_7` in conc `H_2 SO_4` gives :

Options

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Answer

To solve the question "Aniline when treated with K2Cr2O7 in concentrated H2SO4 gives:", we will follow these steps:

### Step 1: Identify the Reactants
We have aniline (C6H5NH2) and potassium dichromate (K2Cr2O7) in concentrated sulfuric acid (H2SO4). Aniline is a primary aromatic amine.

**Hint:** Recognize the structure of aniline and the role of potassium dichromate as a strong oxidizing agent.

### Step 2: Understand the Reaction Conditions
Potassium dichromate in concentrated sulfuric acid provides nascent oxygen, which is crucial for the oxidation process. The acidic medium enhances the oxidation of the amine.

**Hint:** Remember that strong oxidizing agents like K2Cr2O7 can oxidize amines to various products depending on the conditions.

### Step 3: Determine the Oxidation Process
Aniline will undergo oxidation. The oxidation of aniline typically leads to the formation of different products, including quinones. In this case, the oxidation of aniline leads to the formation of para-aminophenol as an intermediate, which can further oxidize to form para-benzoquinone.

**Hint:** Consider the possible oxidation states and structures that can form from aniline under strong oxidizing conditions.

### Step 4: Write the Reaction
The overall reaction can be summarized as:
\[ \text{C}_6\text{H}_5\text{NH}_2 + \text{K}_2\text{Cr}_2\text{O}_7 + \text{H}_2\text{SO}_4 \rightarrow \text{C}_6\text{H}_4\text{O} + \text{Cr}^{3+} + \text{K}_2\text{SO}_4 + \text{H}_2\text{O} \]
Where the product formed is para-benzoquinone (C6H4O).

**Hint:** Focus on the transformation of the amine group (-NH2) into a carbonyl group (C=O) during oxidation.

### Step 5: Identify the Final Product
The final product of the reaction is para-benzoquinone (C6H4O), which is a result of the oxidation of aniline.

**Hint:** Make sure to visualize the structure of para-benzoquinone to confirm it matches the expected product.

### Conclusion
Thus, when aniline is treated with K2Cr2O7 in concentrated H2SO4, the product formed is para-benzoquinone.

**Final Answer:** Para-benzoquinone (C6H4O).