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When the aromatic hydrocarbon naphthalene reacts with nitric and sulfuric acid, two compounds containing one nitro group are formed. What are the structures of these two compounds?

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Hint: The reaction of aromatic hydrocarbon naphthalene with nitric and sulfuric acid is an electrophilic aromatic substitution. The electrophilic substitution reaction contains: nitration, halogenation and alkylation reaction.

Complete answer:
In electrophilic aromatic substitution, naphthalene reacts more readily than benzene. The two compounds formed by the nitration of naphthalene is an electrophilic aromatic substitution which gives two products namely: 1-nitronaphthalene and 2-nitronaphthalene.
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The nitronium ion, $N{O_2}^ + $ is the active nitrating agent in nitric acid-sulfuric acid mixture. Substitution usually occurs more readily at the one position than at the two positions because the intermediate for $1 - $ substitution is more stable than $2 - $ substitution. The reason is that the most favorable resonance structures for either intermediate are those that have one fully aromatic ring.
Nitration at ${1^{st}} - C$ produces a carbocation that has seven resonance structures, which preserve the atomicity of the second ring more favorably.
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Nitration at ${2^{nd}} - C$ produces a carbocation that has six resonance structures, but preserve the atomicity of the second ring less than the first.
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So the attack at first position is more stable intermediate than the attack at the second position intermediate form.
So, the major product is 1-nitronaphthalene and the minor product will be 2-nitronaphthalene.

Note:
The chlorination and bromination of naphthalene proceeds without a catalyst to give 1-chloronaphthalene and 1-bromonaphthalene, respectively. Naphthalene can also be easily alkylated by reaction with alkenes or alcohols, using sulfuric acid or phosphoric acid.