Method by which aniline cannot be prepared is
- degradation of benzamide with bromine in alkaline solution
- reduction of nitrobenzene with H2/Pd in ethanol
- potassium salt of phthalimide treated with chlorobenzene followed by hydrolysis with aqueous NaOH solution
- hydrolysis of phenylisocyanide with acidic solution.
Answer
(3) potassium salt of phthalimide treated with chlorobenzene followed by hydrolysis with aqueous NaOH solution
Solution
(1) Hoffmann bromamide degradation: C6H5CONH2 + Br2 + 4NaOH C6H5NH2 + Na2CO3 + 2NaBr + 2H2O ✓
(2) C6H5NO2 H2/Pd, ethanol C6H5NH2 ✓
(4) C6H5NC + 2H2O H+ C6H5NH2 + HCOOH ✓
(3) As per NCERT, aromatic primary amines cannot be prepared by Gabriel phthalimide synthesis, because aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.
∴ Aniline cannot be prepared by method (3).
Answer: (3)