Benzene Alchemy Practice Problems (Answer Key) Carey, 8 th Edition, Chapter 12 1. Using one sentence, explain why Friedel-Crafts Acylation should be used to add an n-butyl group to benzene instead of Friedel-Crafts Alkylation. Unstable carbocations tend to rearrange for stability in Alkylation, but Acylation prevents this phenomenon. 2. Provide a series of steps to accomplish the following transformations. Keep in mind which substituent is the director after each reaction… Fall, 2018 Page | 1
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Benzene Alchemy Practice Problems (Answer Key)Carey, 8th Edition, Chapter 12
1. Using one sentence, explain why Friedel-Crafts Acylation should be used to add an n-butyl group to benzene instead of Friedel-Crafts Alkylation.
Unstable carbocations tend to rearrange for stability in Alkylation, but Acylation prevents this phenomenon.
2. Provide a series of steps to accomplish the following transformations. Keep in mind which substituent is the director after each reaction…
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Benzene Alchemy Practice Problems (Answer Key)Carey, 8th Edition, Chapter 12
3. Give the product for the following reactions.
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Benzene Alchemy Practice Problems (Answer Key)Carey, 8th Edition, Chapter 12
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Benzene Alchemy Practice Problems (Answer Key)Carey, 8th Edition, Chapter 12
4. Using words and diagrams (mechanisms), explain why phenol is an ortho/para director. Then, generalize your argument to include other activated benzene derivatives.
The hydroxide on phenol can donate electrons into the aromatic ring, as demonstrated by resonance. The negative charge (carbanion) moves around the ring, landing on the ortho and para positions. As such, there is an expected increase in electron density at those positions,
allowing for increased rates of reactivity with electrophiles.
5. On your way to Chick fi la, you stumble into an old friend. It’s only a short time thereafter that this friend, due to a relentless array of questioning, finds out you’ve completed an introductory section on benzene ring reactions. This friend confides in you that they’ve been tasked to synthesize a vital chemical for their research group but have no knowledge benzene reactivity. Being as kind as you are, you offer your new understanding of benzene rings. For the sake of your friend’s success, design the best synthesis of the following compound, starting with 3-iodo-4-methylphenol.FUN FACT: your friend reveals to you that treating an alkene with xenon difluoride adds two fluorines across the double bond.
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Benzene Alchemy Practice Problems (Answer Key)Carey, 8th Edition, Chapter 12
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