question_answer 96)

  Why can aryl halides not be prepared by reaction of phenol with HC1 in the presence of ?

Answer:

                   reactions occur through carbocation intermediates. Obviously more stable the carbocation, more reactive the alkyl halide. Since carbocation obtained from compound (B) by loss of Cl~ ion is stabilized by resonance while that obtained from compound (A) is not stabilized by resonance, therefore, compound (B) reacts faster than compound (A).