question_answer

The ease of nitration of the following three hydrocarbons follows the order

A)  II = III = I                             

B)  II > III > I

C)  III > II > I                             

D)  I = III > II

Correct Answer: B

Solution :

                 The ease of nitration of the hydrocarbons depends upon the stability of arenium ion formed. In compound  II, the carbonium ion has two methyl groups (with \[+\,I\]effect) capable of partially neutralising the positive charges on the ring carbon atoms. In compound I and II, only one methyl group can act in this way. Moreover, in compoumd III two methyl groups has \[+\,I\]effet, whereas in compound I only one methyl group with \[+\,I\]effect is present. Thus, the stability of arenium ion and ease of nitration follows the order II > III > I