Question

Aryl halide is less reactive than alkyl halide towards nucleophilic substitution reaction because:
A. of less stable carbonium ion
B. due to large $C-Cl$ bond energy
C. of inductive effect
D. of resonance stabilization and $s{{p}^{2}}$ hybridization of carbon attached to halide

Answer 1

Nucleophilic reactions are the type of organic reactions in which one nucleophile replaces the other. This reaction is similar with the displacement reaction in which a more reactive element replaces the less reactive one.

Complete Solution :
- Alkyl halide also known by the name haloalkanes or halogenoalkanes which are generally those chemical compounds which are often derived from alkanes which contain one or more halogens. These are formed by the replacement of hydrogen atoms in an aliphatic hydrocarbon by any halogen atom. While aryl halides are the compounds that contain halogen atoms directly attached to the benzene ring.
- Aryl halide is less reactive than alkyl halide towards nucleophilic substitution because of the resonance stabilization and $s{{p}^{2}}$ hybridization of carbon attached to halide. This is due to resonance effect by which carbon-chlorine bond acquires partial double bond character therefore it becomes shorter and stronger and as a result they cannot be easily replaced by nucleophiles. This effect is further increased by the $s{{p}^{2}}$ nature of the carbon atom to which chlorine is attached.
So, the correct answer is “Option D”.

Note: In nucleophilic substitution reaction the group which takes electron pairs and displaced from the carbon is known as the leaving group and the molecule on which substitution takes place are known as substrate.