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Question
The presence of nitro group (−NO2) at o/p positions increases the reactivity of haloarenes towards nucleophilic substitution reactions.
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Solution
The presence of nitro groups (−NO2) at o/p positions increases the reactivity of haloarenes towards nucleophilic substitution reactions because nitro groups (−NO2) at o/p positions withdraw the electron density from the benzene ring facilitating the attack of the nucleophile. The negative charge in the carbanion formed, at ortho and para positions with respect to halogen atom, is stabilised through resonance and the presence of nitro groups (−NO2), respectively.
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RELATED QUESTIONS
Chlorobenzene is extremely less reactive towards a nucleophilic substitution reaction. Give two reasons for the same.
Write the final product(s) in each of the following reactions:
How the following conversion can be carried out?
Chlorobenzene to p-nitrophenol
Assertion: Presence of a nitro group at ortho or para position increases the reactivity of haloarenes towards nucleophilic substitution.
Reason: Nitro group, being an electron-withdrawing group decreases the electron density over the benzene ring.
Which of the following compounds will give racemic mixture on nucleophilic substitution by \[\ce{OH-}\] ion?
(a) \[\begin{array}{cc}
\phantom{}\ce{CH3 - CH - Br}\\
\phantom{}|\\
\phantom{....}\ce{C2H5}\phantom{}
\end{array}\]
(b) \[\begin{array}{cc}
\phantom{..}\ce{Br}\\
\phantom{}|\\
\phantom{}\ce{CH3 - C - CH3}\\
\phantom{}|\\
\phantom{....}\ce{C2H5}\phantom{}
\end{array}\]
(c) \[\begin{array}{cc}
\phantom{....}\ce{CH3 - CH - CH2Br}\\
\phantom{}|\\
\phantom{....}\ce{C2H5}\phantom{}
\end{array}\]
Haloarenes are less reactive than haloalkanes and haloalkenes. Explain.
Allyl chloride is hydrolysed more readily than n-propyl chloride. Why?
\[\ce{C6H12O6 ->[(Zymase)] A ->[NaOH][\Delta] B + CHI3}\]
The number of carbon atoms present in the product B is:
Assertion: Chlorobenzene is resistant to nucleophilic substitution reaction at room temperature.
Reason (R): C–Cl bond gets weaker due, to resonance.
Why haloarenes are not reactive towards nucleophilic substitution reaction? Give two reactions.
