question_answer

  Give reasons: (a) Aromatic amines are less basic than aliphatic amines.                                                                               1 (b) Nitrobenzene does not undergo Friedal-Crafts alkylation.                                                                                     1

Answer:

  (a) Aromatic amines are less basic than aliphatic amines because in aromatic amines lone pair of nitrogen is involved in conjugation due to resonance. Thus the availability of lone pair of donation decreases and acts as weak base.                                                                                                                                                                                               (b) The amine group strongly deactivates the benzene ring towards electrophilic substitution. Hence it does not undergo Fridel-Crafts alkylation.                                                                                                                                               1