Same chapter3 marksDifficulty: Medium
What is meant by an ambident nucleophile? Illustrate with the cyanide ion.
Haloalkanes and Haloarenes
3 marksDifficulty: Medium
Why is chlorobenzene much less reactive towards nucleophilic substitution than chloroethane?
Original Khojo Papers practice question — not from a past board paper.
Answer
In chlorobenzene the lone pair of the chlorine is delocalised into the ring, which gives the carbon-chlorine bond partial double-bond character and shortens and strengthens it. The carbon is also sp2 hybridised and so more electronegative, holding the bonding electrons more tightly, and the ring repels the approaching nucleophile.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
Substitution in chlorobenzene therefore needs forcing conditions, as in the Dow process.
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