Question

Why does Chlorobenzene exhibit very low reactivity towards nucleophilic substitution reaction?

• A. Formation of phenyl cation is highly stable.
• B. It contains a strong C-Cl bond with partial double-bond character.
• C. It easily forms \(SN^{1}\) intermediate.
• D. The C-Cl bond in chlorobenzene is very weak.

Hint:

Resonance between chlorine lone pairs and the ring gives the C-Cl bond partial double-bond character.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Haloarenes are much less reactive than haloalkanes towards nucleophilic substitution.

Step 2: Resonance Effect
The lone pair on chlorine is delocalised into the benzene ring.
This gives the C-Cl bond partial double-bond character, making it shorter and stronger.

Step 3: Other Factors
The carbon bonded to Cl is \(sp^{2}\) hybridised, and the phenyl cation is very unstable, so \(SN^{1}\) is not favoured.

Step 4: Compare the options
Option (B) states the strong C-Cl bond with partial double-bond character, which is correct.

Final Answer:
The C-Cl bond is strong with partial double-bond character. \[ \boxed{\text{(B) }\text{It contains a strong C-Cl bond with partial double-bond character.}} \]