Question

When benzene diazonium chloride is treated with ethanol, the product obtained is:

• A. Aniline
• B. Phenetole
• C. Benzene
• D. p-Chloro phenol

Hint:

For diazonium reactions:

- Ethanol reduces \({ArN2^+}\)\ to \({ArH} + {N2}\).

- Other reagents (e.g., \({CuCl}\), \({H3PO2}\)) yield different products.

- Determine the reagent’s role (reducing or coupling).

Answer 1

The Correct Option is C

Benzene diazonium chloride (\({C_6H_5N_2Cl}\)) is a reactive compound used in various transformations. Its reaction with ethanol involves a reduction process.
Step 1: Reaction mechanism 
Ethanol (\({C_2H_5OH}\)) acts as a mild reducing agent, converting the diazonium group (\({-N_2^+}\)) to nitrogen gas and forming benzene: \[ {C_6H_5N_2^+ + C_2H_5OH -> C_6H_6 + N_2 + CH_3CHO + H^+} \] Ethanol is oxidized to acetaldehyde (\({CH_3CHO}\)), and the diazonium ion releases \({N_2}\), yielding benzene (\({C_6H_6}\)). 
Step 2: Analyze options 
- (A) Aniline (\({C_6H_5NH_2}\)): Formed by strong reduction (e.g., \({Sn/HCl}\)), not ethanol. 
- (B) Phenetole (\({C_6H_5OC_2H_5}\)): Requires phenol and ethanol under different conditions. 
- (C) Benzene (\({C_6H_6}\)): Correct, as ethanol reduces the diazonium ion. 
- (D) p-Chloro phenol: Involves chlorination and phenolic conditions, not relevant. 
Step 3: Conclusion 
The product is benzene, matching option (C).