Textbook Question
Propose a mechanism that shows why p-chlorotoluene reacts with sodium hydroxide at 350 °C to give a mixture of p-cresol and m-cresol.
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Ch. 17 - Reactions of Aromatic Compounds
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 17, Problem 20g
Show how you would use the Friedel–Crafts acylation, Clemmensen reduction, and/or Gatterman–Koch synthesis to prepare the following compounds:
g. n-butylbenzene
Verified step by step guidance1
Start by analyzing the target molecule, n-butylbenzene. It consists of a benzene ring attached to a straight-chain butyl group (C4H9). The goal is to introduce this alkyl group onto the benzene ring.
Use Friedel–Crafts acylation to introduce a four-carbon chain with a carbonyl group (butanoyl group) onto the benzene ring. This reaction involves reacting benzene with butanoyl chloride (CH3CH2CH2COCl) in the presence of a Lewis acid catalyst such as AlCl3. The product will be 1-phenyl-1-butanone (C6H5COCH2CH2CH3).
Next, perform a Clemmensen reduction to convert the carbonyl group in 1-phenyl-1-butanone to a methylene group (-CH2-). This reduction is carried out using zinc amalgam (Zn(Hg)) and concentrated hydrochloric acid (HCl). The product will be n-butylbenzene (C6H5CH2CH2CH2CH3).
Alternatively, you could use the Gatterman–Koch synthesis to introduce a formyl group (-CHO) onto the benzene ring, followed by chain elongation reactions to achieve the n-butyl group. However, this approach is less direct and involves additional steps.
Verify the structure of the final product, n-butylbenzene, to ensure that the desired substitution pattern has been achieved. The benzene ring should be attached to a straight-chain butyl group (C4H9) without any branching or additional functional groups.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Friedel–Crafts Acylation
Friedel–Crafts acylation is an electrophilic aromatic substitution reaction that introduces an acyl group into an aromatic ring. This reaction typically uses an acyl chloride and a Lewis acid catalyst, such as aluminum chloride, to form a ketone. The acyl group enhances the reactivity of the aromatic compound, allowing for further transformations, making it a valuable method for synthesizing substituted aromatic compounds.
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Friedel-Crafts Acylation
Clemmensen Reduction
The Clemmensen reduction is a chemical reaction that reduces carbonyl groups (aldehydes and ketones) to alkanes using zinc amalgam and hydrochloric acid. This method is particularly useful for converting aromatic ketones into the corresponding alkylated aromatic compounds without affecting other functional groups. It is a key reaction in organic synthesis for simplifying complex molecules.
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07:12Reductive Amination
Gatterman–Koch Synthesis
The Gatterman–Koch synthesis is a method for synthesizing aromatic aldehydes through the formylation of aromatic compounds using carbon monoxide and hydrochloric acid in the presence of a Lewis acid catalyst. This reaction allows for the introduction of a formyl group (-CHO) into the aromatic ring, which can then be further manipulated in subsequent reactions, making it a powerful tool in organic synthesis.
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Related Practice
Textbook Question
Show how you would use the Friedel–Crafts acylation, Clemmensen reduction, and/or Gatterman–Koch synthesis to prepare the following compounds:
b.
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Textbook Question
Show how you would use the Friedel–Crafts acylation, Clemmensen reduction, and/or Gatterman–Koch synthesis to prepare the following compounds:
f. 1-phenyl-2,2-dimethylpropane
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Textbook Question
Propose mechanisms and show the expected products of the following reactions.
(a) 2,4-dinitrochlorobenzene + sodium methoxide (NaOCH3)
(b) 2,4-dimethylchlorobenzene + sodium hydroxide, 350 °C
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Textbook Question
Show how you would use the Friedel–Crafts acylation, Clemmensen reduction, and/or Gatterman–Koch synthesis to prepare the following compounds:
c.
1120
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Textbook Question
Show how you would use the Friedel–Crafts acylation, Clemmensen reduction, and/or Gatterman–Koch synthesis to prepare the following compounds:
h.
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