Question

Which of the following sets of reagents convert toluene to benzaldehyde? \includegraphics[]{158.png}

• A. \( B, C, D \)
• B. \( A, C \)
• C. \( A, D \)
• D. \( B, D \)

Hint:

To convert toluene to benzaldehyde, use selective oxidation methods such as the Etard reaction (CrO\(_2\)Cl\(_2\)) or controlled halogenation with Cl\(_2\)/hv, H\(_2\)O.

Answer 1

The Correct Option is C

Step 1: Identify the Reagents for Partial Oxidation
The conversion of toluene to benzaldehyde involves partial oxidation. The effective reagents for this reaction are:
- Chromyl chloride (\( CrO_2Cl_2 \)) in CS\(_2\), H\(_3O^+\) (Etard reaction)
- Chlorine (\( Cl_2 \)) in the presence of light and water Step 2: Explanation
- \( A: Cl_2/ hv, H_2O, \triangle \) → Effective (Partial oxidation of toluene to benzaldehyde)
- \( B: Cl_2/Fe; H_2O \) → Ineffective (Leads to benzoic acid)
- \( C: KMnO_4/ OH^-; H^+ \) → Ineffective (Complete oxidation to benzoic acid)
- \( D: CrO_2Cl_2/CS_2; H_3O^+ \) → Effective (Etard reaction forms benzaldehyde)
Thus, the correct answer is \( A, D \).