Textbook Question
Predict the products of the following reactions. An excess of acid is available in each case.
(c) anisole (methoxybenzene) + HBr
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12. Alcohols, Ethers, Epoxides and Thiols
Ether Cleavage
Problem 33b
Textbook Question
Predict the product of the following reactions.
(b) 
Verified step by step guidance1
Identify the functional groups present in the molecule. The structure contains an amide group, an ether linkage, and a benzene ring.
Recognize the reagents used in the reaction: H2 and Pd0. This combination is typically used for hydrogenation reactions, which can reduce double bonds and other unsaturated systems.
Determine the parts of the molecule that can be affected by hydrogenation. In this case, the benzene ring is a potential site for hydrogenation, as it can be reduced to a cyclohexane ring under certain conditions.
Consider the stability and reactivity of the functional groups. The amide group is generally stable under hydrogenation conditions, so it is unlikely to be reduced.
Predict the product by considering the reduction of the benzene ring to a cyclohexane ring, while the rest of the molecule remains unchanged. The ether linkage and the amide group should remain intact.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Catalytic Hydrogenation
Catalytic hydrogenation involves the addition of hydrogen (H2) to unsaturated bonds, typically using a metal catalyst like palladium (Pd). This process converts alkenes and alkynes into alkanes by breaking double or triple bonds, resulting in a saturated compound. In the given reaction, Pd0 acts as the catalyst facilitating the hydrogenation of any unsaturated bonds present in the molecule.
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General properties of catalytic hydrogenation.
Amide Functional Group
An amide is a functional group characterized by a carbonyl group (C=O) linked to a nitrogen atom (N). Amides are generally stable and resistant to hydrogenation under typical conditions, meaning they usually remain unchanged in reactions involving hydrogen and metal catalysts. In the given structure, the amide group is unlikely to be affected by the hydrogenation process.
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Aromatic Stability
Aromatic compounds, like benzene rings, exhibit exceptional stability due to resonance, where electrons are delocalized across the ring structure. This stability makes aromatic rings resistant to hydrogenation under standard conditions. In the reaction, the benzene ring is expected to remain intact, as hydrogenation typically does not disrupt aromatic systems without specific conditions.
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