JEE MainChemistryAmines
Which of the following sequences of reagents will successfully convert benzyl chloride into phenyl isocyanide?
Options
- A(i) Alk. KMnO₄, then H₃O^+ (ii) SOCl₂ , then NH₃ (iii) Br₂, NaOH (iv) CHCl₃, KOH,
- B(i) KCN (ii) H₃O^+, (iii) NH₃, (iv) Br₂, KOH (v) CHCl₃, KOH,
- C(i) NH₃ (excess) (ii) CHCl₃, KOH,
- D(i) Alk. KMnO₄, then H₃O^+ (ii) NH₃ (room temperature) (iii) Br₂, NaOH (iv) CHCl₃, KOH,
Correct answer
A. (i) Alk. KMnO₄, then H₃O^+ (ii) SOCl₂ , then NH₃ (iii) Br₂, NaOH (iv) CHCl₃, KOH,
Step-by-step solution
The transformation requires converting benzyl chloride ( C₆H₅CH₂Cl ) into phenyl isocyanide ( C₆H₅NC ). This involves removing one carbon atom from the side chain. Step 1: Oxidation of the benzylic carbon. Benzyl chloride is oxidized by alkaline KMnO₄ upon heating, followed by acidification, to yield benzoic acid ( C₆H₅COOH ). Step 2: Conversion to an amide. Benzoic acid reacts with SOCl₂ to form benzoyl chloride, which upon treatment with NH₃ yields benzamide ( C₆H₅CONH₂ ). Step 3: Hoffmann bromamide degradation.