Question

The decreasing order of reactivity towards electrophilic substitution of the following compounds is

• A. $1 > 3 > 4 > 2$
• B. $4 > 1 > 3 > 2$
• C. $4 > 1 > 2 > 3$
• D. $1 > 4 > 3 > 2$

Answer 1

Answer: (C)

$4 > 1 > 2 > 3$

Answer 2

Due to $+I$ effect of ${-CH_3}$ group (4) has higher electron density than benzene (1).
Due to strong $-I$ effect of $-Cl$ group and strong $-I$ and $-M$ effects of $-N O_2$ group, both (2) and (3) have lower electron density than benzene (1).
As -I effect of -Cl group is weaker than that of $-NO_2$, (3) has much lower electron density than (2).
Thus the overall reactivity order towards electrophilic substitution is
4 > 1 > 2 > 3