Question

$C_6{H}_{5}Cl$ is less reactive towards nucleophilic substitution reactions than $C_2{H}_{5}Cl.$ Explain.

Answer 1

In chloroethane, the $C$-atom of $C-Cl$ bond is $s{p}^3$ hybridised while in $C_6{H}_{5}Cl,$ the carbon atom is in $s{p}^2$ hybridisation state.

The $s{p}^2$ hybridised $C$- an atom with a greater s-character is more electronegative and can hold the electron pair of the $C-Cl$ bond more tightly than $s{p}^3$- hybridised $C$-atom in chloroethane with less s-character. Thus the bond cleavage in chlorobenzene is more difficult and is, therefore, less reactive as compared to chloroethane.