Question

Rank the following in the decreasing order of their rates with methoxide ion $\left(C{H}_3{O}^{-}\right)$ in a nucleophilic aromatic substitution.

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

Answer 1

The correct option is A $3>4>1>2$

$N{O}_2$ shows -R as well as -I effect but former predominates when the substitution occurs at ortho or para position to $N{O}_2$ group.
[3] will be the most reactive as both nitrogen are at ortho and para to leaving group.
[2] will be the least reactive as only -I effect is working.
Hence the order is: $3>4>1>2$