Benzene and Alkyl Benzene - Result Question 32
36. Explain the followings :
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Solution:
Nitro group from para position deactivates aromatic nucleophilic substitution.
$-\mathrm{NO}_2$ is not in resonance with benzene ring, does not activate the aromatic electrophilic substitution reaction, hence fluoride is not formed.
Hence, -NO2 is ortho/para directing although deactivating group. Therefore, ortho/para nitro derivatives are formed on treatment with mixed acid.
Nitro group is meta directing as well as strongly deactivating.
In the above hydrogenation reaction, the anti-aromatic character of three cyclobutadiene rings is relieved, which provides stability to the hydrogenation product.
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