question_answer

                The correct order of reactivity towards the electrophilic substitution of the compounds aniline (I), benzene (II) and nitrobenzene (III) is:                                                                                                                           

A)                 II < III > I                

B)                 I > II > III

C)                                             III > II > I 

D)                 II > III > I

Correct Answer: B

Solution :

                In aniline \[-N{{H}_{2}}\]group is attached with benzene ring. \[-N{{H}_{2}}\]group shows +M effect. So it activates the benzene ring. Hence, rate of electrophilic substitution is increased due to increase in the electron density at o/p position. In case of nitrobenzene, \[-N{{O}_{2}}\]deactivates the benzene ring, so in nitrobenzene rate of electrophilic substitution is lower than benzene. Hence order of \[{{S}_{E}}\] reaction: