Textbook Question
Show how the following compounds can be synthesized from benzene:
a.
833
views
19. Reactions of Aromatics: EAS and Beyond
EAS:Retrosynthesis
2:52 minutesProblem 31d
Textbook Question
Show how the following compounds can be synthesized from benzene:
d. m-methylnitrobenzene
Verified step by step guidance1
Step 1: Begin with benzene as the starting material. Benzene is a simple aromatic compound with a planar, cyclic structure and alternating double bonds, making it highly stable and reactive in electrophilic aromatic substitution reactions.
Step 2: Introduce a nitro group (-NO₂) to the benzene ring through a nitration reaction. This is achieved by treating benzene with a mixture of concentrated sulfuric acid (H₂SO₄) and concentrated nitric acid (HNO₃). The reaction generates the nitronium ion (NO₂⁺), which acts as the electrophile. The product is nitrobenzene.
Step 3: Introduce a methyl group (-CH₃) to the meta position relative to the nitro group. Since the nitro group is a meta-directing group due to its electron-withdrawing nature, a Friedel-Crafts alkylation reaction can be used. Treat nitrobenzene with methyl chloride (CH₃Cl) in the presence of a Lewis acid catalyst, such as aluminum chloride (AlCl₃). This will result in the formation of m-methylnitrobenzene.
Step 4: Carefully control the reaction conditions to avoid over-alkylation or side reactions. Ensure that the methyl group is added only once and that the meta position is favored due to the directing effects of the nitro group.
Step 5: Purify the product, m-methylnitrobenzene, using appropriate techniques such as recrystallization or distillation to ensure the desired compound is isolated in high purity.
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Video duration:
2mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Electrophilic Aromatic Substitution
Electrophilic aromatic substitution (EAS) is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. This process is crucial for synthesizing various substituted aromatic compounds, including nitro and alkyl derivatives. Understanding EAS mechanisms, such as the role of the electrophile and the stability of the intermediates, is essential for predicting the products formed from benzene.
Recommended video:
Guided course
03:07
EAS Review
Nitration of Aromatic Compounds
Nitration is a specific type of electrophilic aromatic substitution where a nitro group (-NO2) is introduced into an aromatic ring. This reaction typically involves the use of a nitrating mixture, such as concentrated nitric acid and sulfuric acid, to generate the nitronium ion (NO2+), the active electrophile. Recognizing the conditions and regioselectivity of nitration is vital for synthesizing compounds like m-methylnitrobenzene from benzene.
Recommended video:
Guided course
08:19Intro to Aromaticity
Regioselectivity in Substitution Reactions
Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In the case of m-methylnitrobenzene synthesis, understanding how the existing methyl group influences the position where the nitro group is added is crucial. The methyl group is an ortho/para-directing group, but due to steric hindrance, the nitro group will preferentially attach at the meta position in this specific synthesis.
Recommended video:
Guided course
01:34Recognizing Substitution Reactions.
Related Videos
Related Practice