Question

The above reaction will undergo $S_{N}Ar$ i.e. Substitution Nucleophilic aromatic reaction if:

• A. $\text{Basicity of}{X}^{-}>\text{Basicity of}{Y}^{-}$
• B. $\text{Basicity of}{X}^{-}<\text{Basicity of}{Y}^{-}$
• C. $\text{Basicity of}{X}^{-}=\text{Basicity of}{Y}^{-}$
• D. None of the above.

Answer 1

The correct option is B $\text{Basicity of}{X}^{-}<\text{Basicity of}{Y}^{-}$

In $S_{N}Ar$ reaction:
$\text{Basicity of incoming nucleophile}>\text{Basicity of outgoing leaving group}$
The intermediate formed:

Since weaker base is a good leaving group.
That group would be eliminated whose anion would be weaker base after elimination.
When
$\text{Basicity of}{X}^{-}<\text{Basicity of}{Y}^{-}$
the given reactions occurs to form the desired product.