Textbook Question
What products would you expect from the following coupling reactions?
(d)
(e)
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19. Reactions of Aromatics: EAS and Beyond
Benzene Reactions
Multiple Choice
Which of the following is a correct method to prepare (nitrobenzene) from benzene?
A
Friedel–Crafts alkylation of benzene with methyl chloride and
B
Bromination of benzene with and iron(III) bromide
C
Sulfonation of benzene with fuming
D
Nitration of benzene using concentrated and
Verified step by step guidance1
Identify the target compound: nitrobenzene (PhNO\_2), which contains a nitro group (-NO\_2) attached to a benzene ring.
Recall that electrophilic aromatic substitution (EAS) reactions are commonly used to introduce substituents onto benzene rings, such as nitration, sulfonation, halogenation, and Friedel–Crafts alkylation/acylation.
Understand that nitration of benzene involves generating the nitronium ion (NO\_2\^+) as the electrophile, which is typically formed by mixing concentrated sulfuric acid (H\_2SO\_4) and concentrated nitric acid (HNO\_3). The reaction proceeds as:
\[\mathrm{HNO_3 + 2H_2SO_4 \rightarrow NO_2^+ + H_3O^+ + 2HSO_4^-}\]
Recognize that the nitronium ion (NO\_2\^+) attacks the benzene ring in an electrophilic aromatic substitution mechanism, replacing one hydrogen atom and forming nitrobenzene.
Compare other options: Friedel–Crafts alkylation introduces alkyl groups, bromination introduces bromine substituents, and sulfonation introduces sulfonic acid groups, none of which produce nitrobenzene. Therefore, nitration using concentrated H\_2SO\_4 and HNO\_3 is the correct method.
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