Textbook Question
For each pair, choose the haloalkane that would react most quickly in an SN1 or E1 reaction.
(a)
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Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
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Mullins 1st EditionCh. 12 - Substitution and Elimination: Reactions of HaloalkanesProblem 59b
Mullins 1st EditionCh. 12 - Substitution and Elimination: Reactions of HaloalkanesProblem 59bChapter 11, Problem 59b
For each pair, choose the haloalkane that would react most quickly in an SN1 or E1 reaction.
(b) 
Verified step by step guidance1
Step 1: Understand the reaction mechanism. SN1 and E1 reactions proceed via a carbocation intermediate. The stability of the carbocation formed after the leaving group departs is a key factor in determining the rate of the reaction.
Step 2: Analyze the first haloalkane (cyclohexyl iodide). When the iodine leaves, it forms a secondary carbocation. Secondary carbocations are moderately stable, but not as stable as tertiary carbocations.
Step 3: Analyze the second haloalkane (cyclohexyl iodide with a double bond and methyl group). When the iodine leaves, it forms an allylic carbocation. Allylic carbocations are stabilized by resonance, making them more stable than secondary carbocations.
Step 4: Compare the stability of the carbocations formed. The allylic carbocation formed from the second haloalkane is more stable due to resonance stabilization, which increases the rate of SN1 and E1 reactions.
Step 5: Conclude that the second haloalkane (with the double bond and methyl group) will react more quickly in an SN1 or E1 reaction because the carbocation intermediate is more stable.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Sₙ1 and E1 Reactions
Sₙ1 (nucleophilic substitution unimolecular) and E1 (elimination unimolecular) reactions are two types of reactions that involve a two-step mechanism. In Sₙ1 reactions, the rate-determining step is the formation of a carbocation intermediate, while in E1 reactions, the same intermediate is formed before the elimination of a leaving group. Both reactions are favored by tertiary haloalkanes due to their ability to stabilize the carbocation.
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03:32
Understanding the properties of E1.
Carbocation Stability
Carbocation stability is a crucial factor in determining the rate of Sₙ1 and E1 reactions. Tertiary carbocations are more stable than secondary or primary ones due to hyperconjugation and inductive effects from surrounding alkyl groups. The more stable the carbocation, the faster the reaction will proceed, making the structure of the haloalkane significant in predicting reactivity.
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05:58Determining Carbocation Stability
Leaving Group Ability
The ability of a leaving group to depart from the haloalkane is essential in both Sₙ1 and E1 reactions. Good leaving groups, such as iodide or bromide, can stabilize the transition state and facilitate the formation of the carbocation. The strength of the leaving group can significantly influence the reaction rate, with weaker bases generally being better leaving groups.
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03:06How to use the factors affecting acidity to predict leaving group ability.
Related Practice
Textbook Question
Suggest a bromoalkane and the conditions necessary to produce the alkenes shown.
(a)
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Textbook Question
For each pair, choose the haloalkane that would react most quickly in an SN2 reaction.
(d)
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Textbook Question
Suggest a bromoalkane and the conditions necessary to produce the alkenes shown.
(b)
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Textbook Question
For each pair, choose the haloalkane that would react most quickly in an Sₙ1 or E1 reaction.
(c)
1491
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Textbook Question
For each pair, choose the haloalkane that would react most quickly in an SN2 reaction.
(c)
888
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