Textbook Question
Give the substitution and elimination products you would expect from the following reactions.
a. 3-bromo-3-ethylpentane heated in methanol
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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 20c
Give the substitution and elimination products you would expect from the following reactions.
c. 1-bromo-2-methylcyclohexane + silver nitrate in water (AgNO3 forces ionization)
Verified step by step guidance1
Identify the reaction conditions: Silver nitrate (AgNO3) in water is a polar protic solvent that promotes ionization of the alkyl halide, favoring the formation of a carbocation intermediate. This suggests the reaction will proceed via an SN1 (substitution) and/or E1 (elimination) mechanism.
Analyze the structure of the substrate: 1-bromo-2-methylcyclohexane is a secondary alkyl halide. Upon ionization, the bromide ion (Br⁻) will leave, forming a secondary carbocation at the 1-position of the cyclohexane ring.
Consider carbocation stability: The secondary carbocation formed at the 1-position is relatively stable, but it can undergo a hydride shift from the 2-position (where the methyl group is attached) to form a more stable tertiary carbocation. This rearrangement is likely to occur.
Determine the substitution product: In the SN1 mechanism, water (H₂O) acts as the nucleophile and attacks the carbocation, leading to the formation of an alcohol. The final product will depend on whether the carbocation rearranges or not, but the major product will likely involve the tertiary alcohol due to the stability of the rearranged carbocation.
Determine the elimination product: In the E1 mechanism, a β-hydrogen (a hydrogen on a carbon adjacent to the carbocation) is removed by water, leading to the formation of a double bond. The major elimination product will follow Zaitsev's rule, where the more substituted alkene is favored. This will depend on the position of the carbocation and the available β-hydrogens.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Substitution Reactions
Substitution reactions involve the replacement of one functional group in a molecule with another. In organic chemistry, this often occurs with alkyl halides, where a nucleophile attacks the carbon atom bonded to the halogen, leading to the formation of a new bond and the release of the halide ion. Understanding the mechanism (SN1 or SN2) is crucial for predicting the products.
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01:34
Recognizing Substitution Reactions.
Elimination Reactions
Elimination reactions involve the removal of a small molecule from a larger one, typically resulting in the formation of a double bond. In the context of alkyl halides, this can occur through mechanisms such as E1 or E2, where a base abstracts a proton, and the leaving group departs simultaneously or sequentially. The conditions and structure of the substrate influence the pathway and products formed.
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00:40Recognizing Elimination Reactions.
Nucleophiles and Electrophiles
Nucleophiles are species that donate an electron pair to form a chemical bond, while electrophiles are electron-deficient species that accept electron pairs. In the reaction of 1-bromo-2-methylcyclohexane with silver nitrate in water, the silver ion can facilitate the ionization of the bromide, making the carbon more electrophilic and susceptible to attack by nucleophiles or elimination by bases present in the solution.
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03:Nucleophile or Electrophile
Related Practice
Textbook Question
The solvolysis of 2-bromo-3-methylbutane potentially can give several products, including both E1 and products from both the unrearranged carbocation and the rearranged carbocation. Mechanisms 6-6 and 7-2 show the products from the rearranged carbocation. Summarize all the possible products, showing which carbocation they come from and whether they are the products of E1 or reactions.
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Textbook Question
When (1-bromoethyl)cyclohexane is heated in methanol for an extended period of time, five products result: two ethers and three alkenes. Predict which of the three alkenes is the major elimination product.
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Textbook Question
Give the substitution and elimination products you would expect from the following reactions.
b. 1-iodo-1-phenylcyclopentane heated in ethanol
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Textbook Question
When (1-bromoethyl)cyclohexane is heated in methanol for an extended period of time, five products result: two ethers and three alkenes. Predict the products of this reaction, and propose mechanisms for their formation.
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Textbook Question
Under second-order conditions (strong base/nucleophile), SN2 and E2 reactions may occur simultaneously and compete with each other. Show what products might be expected from the reaction of 2-bromo-3-methylbutane (a moderately hindered 2° alkyl halide) with sodium ethoxide.
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