Textbook Question
Show how you would convert (in one or two steps) 1-phenylpropane to the three products shown below. In each case, explain what unwanted reactions might produce undesirable impurities in the product.
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Ch. 7 - Structure and Synthesis of Alkenes; Elimination
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 7, Problem 57c
Show how you would prepare cyclopentene from each compound.
c. cyclopentane (not by dehydrogenation)
Verified step by step guidance1
Identify the target transformation: The goal is to convert cyclopentane (a saturated hydrocarbon) into cyclopentene (an unsaturated hydrocarbon with one double bond). This requires the introduction of a double bond through an elimination reaction.
Choose a suitable reagent to introduce a leaving group: Since cyclopentane lacks functional groups, it must first be functionalized. Bromination using Br₂ in the presence of UV light (a free radical halogenation reaction) can be used to introduce a bromine atom, forming bromocyclopentane.
Plan the elimination step: To form the double bond, perform a β-elimination (E2 mechanism) on bromocyclopentane. Use a strong base, such as potassium tert-butoxide (KOtBu) or sodium ethoxide (NaOEt), to abstract a β-hydrogen, leading to the formation of cyclopentene.
Consider reaction conditions: Ensure the reaction conditions favor elimination over substitution. Use a strong, bulky base and heat to promote the E2 mechanism.
Verify the product: Confirm that the product is cyclopentene by analyzing its structure, ensuring the double bond is correctly formed in the cyclopentane ring.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Cyclopentene Structure and Properties
Cyclopentene is a five-membered cyclic alkene with one double bond. Understanding its structure is crucial for recognizing how it can be synthesized from other compounds. Its reactivity is influenced by the presence of the double bond, which can participate in various chemical reactions, making it a key target in organic synthesis.
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Reactions of Cyclopentane
Cyclopentane is a saturated hydrocarbon (alkane) that can be transformed into cyclopentene through elimination reactions. While dehydrogenation is a common method, the question specifies avoiding this route, prompting the exploration of alternative reactions such as ring-opening or rearrangement processes that can lead to the formation of cyclopentene.
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00:21Is the following disubstituted cyclopentane chiral?
Elimination Reactions
Elimination reactions involve the removal of atoms or groups from a molecule, resulting in the formation of a double bond. In the context of converting cyclopentane to cyclopentene, understanding mechanisms like E2 or E1 eliminations is essential. These reactions often require specific conditions, such as the presence of a strong base or heat, to facilitate the removal of hydrogen and a leaving group.
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00:40Recognizing Elimination Reactions.
Related Practice
Textbook Question
Using cyclohexane as your starting material, show how you would synthesize each of the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.)
a. bromocyclohexane
b. cyclohexene
c. ethoxycyclohexane
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Textbook Question
Show how you would convert (in one or two steps) 1-phenylpropane to the three products shown below. In each case, explain what unwanted reactions might produce undesirable impurities in the product.
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Textbook Question
Show how you would convert (in one or two steps) 1-phenylpropane to the three products shown below. In each case, explain what unwanted reactions might produce undesirable impurities in the product.
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Textbook Question
Show how you would prepare cyclopentene from each compound.
a. cyclopentanol
b. cyclopentyl bromide
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Textbook Question
Using cyclohexane as your starting material, show how you would synthesize each of the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.)
d. 3-bromocyclohex-1-ene
e. cyclohexa-1,3-diene
f. cyclohexanol
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