Textbook Question
Show how you might synthesize the following compounds starting with bromobenzene, and alkyl or alkenyl halides of four carbon atoms or fewer.
a. 3-phenylprop-1-ene
Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy
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
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Wade 9th EditionCh. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet SpectroscopyProblem 13b
Wade 9th EditionCh. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet SpectroscopyProblem 13bChapter 15, Problem 13b
Show how you might synthesize the following compounds starting with bromobenzene, and alkyl or alkenyl halides of four carbon atoms or fewer.
b. 5-methylhex-2-ene
Verified step by step guidance1
Step 1: Begin with bromobenzene as the starting material. Perform a Friedel-Crafts alkylation reaction using a suitable alkyl halide (e.g., 1-bromopropane) and a Lewis acid catalyst such as AlCl₃. This will introduce a propyl group onto the benzene ring, forming propylbenzene.
Step 2: Perform a benzylic bromination on the propylbenzene using N-bromosuccinimide (NBS) and light (hv) to selectively brominate the benzylic position, forming 1-bromo-3-phenylpropane.
Step 3: Carry out a Wurtz reaction by reacting 1-bromo-3-phenylpropane with an alkyl halide (e.g., methyl iodide) in the presence of sodium metal. This will couple the two alkyl chains, forming 5-phenylhexane.
Step 4: Perform a dehydrohalogenation reaction to introduce a double bond. Use a strong base such as potassium tert-butoxide (t-BuOK) to eliminate a hydrogen and a halogen, forming 5-phenylhex-2-ene.
Step 5: Finally, perform a hydrogenation reaction using a catalyst such as Pd/C and hydrogen gas (H₂) to selectively remove the phenyl group, leaving behind 5-methylhex-2-ene as the desired product.
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Key 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. In the case of bromobenzene, the bromine atom can be replaced by various electrophiles, allowing for the introduction of different substituents. Understanding EAS is crucial for synthesizing compounds from aromatic starting materials.
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EAS Review
Alkylation Reactions
Alkylation reactions involve the introduction of an alkyl group into a molecule, often through nucleophilic substitution or EAS. When synthesizing 5-methylhex-2-ene, alkyl halides can be used to add carbon chains to the aromatic ring or to create branched alkenes. Mastery of alkylation techniques is essential for constructing complex organic molecules.
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Elimination Reactions
Elimination reactions are processes where two atoms or groups are removed from a molecule, resulting in the formation of a double bond. In the synthesis of 5-methylhex-2-ene, elimination reactions can be employed to convert alkyl halides into alkenes. Understanding the mechanisms and conditions for elimination is vital for achieving the desired product in organic synthesis.
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00:40Recognizing Elimination Reactions.
Related Practice
Textbook Question
Show how you might synthesize the following compounds starting with bromobenzene, and alkyl or alkenyl halides of four carbon atoms or fewer.
c. dec-5-ene
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Textbook Question
Predict the products of the following proposed Diels–Alder reactions.
(b)
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Textbook Question
Predict the products of the following proposed Diels–Alder reactions.
(a)
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Textbook Question
When N-bromosuccinimide is added to hex-1-ene in CCl4 and a sunlamp is shone on the mixture, three products result.
(a) Give the structures of these three products.
(b) Propose a mechanism that accounts for the formation of these three products
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Textbook Question
Addition of 1-bromobut-2-ene to magnesium metal in dry ether results in formation of a Grignard reagent. Addition of water to this Grignard reagent gives a mixture of but-1-ene and but-2-ene (cis and trans). When the Grignard reagent is made using 3-bromobut-1-ene, addition of water produces exactly the same mixture of products in the same ratios. Explain this curious result
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