Benzene and Alkyl Benzene - Result Question 32

36. Explain the followings :

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Solution:

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Nitro group from para position activate aromatic nucleophilic substitution.

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$-\mathrm{NO}_2$ is not in resonance with benzene ring, does not activate the aromatic nucleophilic substitution reaction, hence fluoride is not formed.

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Hence, -NO is ortho/para directing although deactivating group. Therefore, ortho/para nitro derivatives are formed on treatment with mixed acid.

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Nitro group is meta directing as well as strongly deactivating.

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In the above hydrogenation reaction, the anti-aromatic character of three cyclobutadiene rings are relieved that provide stability to the hydrogenation product.



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