Question

Which of the following sequence of reagents convert benzaldehyde to 4-chlorotoluene?

• A. \( \text{NaBH}_4 ; \, \text{Cl}_2 | Fe\)
• B. \( \text{NaBH}_4 ; \, \text{Cl}_2| \, \text{hv} \)
• C. \( \text{Zn}-\text{Hg}, \, \text{HCl};\text{Cl}_2 \,| \text{Fe} \)
• D. \( \text{Zn}-\text{Hg}, \, \text{Cl}_2 |\, \text{hv} \)

Hint:

In organic reactions, the Clemmensen reduction is a classic method for reducing aldehydes to alkanes, and halogenation of aromatic compounds is often facilitated by halogens and light.

Answer 1

The Correct Option is C

The given reaction shows the conversion of benzaldehyde to 4-chlorotoluene. We need to choose the correct sequence of reagents for this transformation. The process involves the reduction of the carbonyl group in benzaldehyde and chlorination of the resulting toluene.
- The reduction of the aldehyde group to a methyl group is typically done using \( \text{Zn}-\text{Hg} \) in the Clemmensen reduction.
- The chlorination of the methyl group is achieved by using chlorine gas in the presence of heat or ultraviolet light.
Thus, the correct sequence of reagents is \( \text{Zn}-\text{Hg}, \, \text{HCl};\text{Cl}_2 \,| \text{Fe} \)