question_answer

The order of decreasing reactivity towards an electrophilic reagent, for the following:    [AIPMT (S) 2007]

(i) Benzene

(ii) Toluene

(iii) Chlorobenzene and

(iv) Phenol would be:

A) (i) > (ii) > (iii) > (iv)

B)      (ii) > (iv) > (i) > (iii)

C) (iv) > (iii) > (ii) > (i)

D) (iv) > (ii) > (i) > (iii)

Correct Answer: D

Solution :

[d] Benzene having any activating group i.e., OH, R etc., undergoes electrophilic substitution very easily as compared to benzene itself. Thus toluene (C6H5CH3), phenol (C6H5OH) undergo electrophilic substitution very readily than benzene. Chlorine with +E and +M effect deactivates the ring due to strong -I effect. So, it is difficult to carry out the substitution in chlorobenzene than in benzene, so correct order is