Textbook Question
A trifluoromethanesulfonate (triflate) can be used in a manner similar to tosylates. Which would you expect to be a better leaving group? Why?
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Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination
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. 13 - Alcohols, Ethers and Related Compounds: Substitution and EliminationProblem 90c
Mullins 1st EditionCh. 13 - Alcohols, Ethers and Related Compounds: Substitution and EliminationProblem 90cChapter 12, Problem 90c
Identify whether each of the following reactions proceed by an SN1, SN2, E1, or E2 mechanism.
(c) 
Verified step by step guidance1
Analyze the substrate: The substrate is a benzylic sulfonate ester, which is a good leaving group. The benzylic position is stabilized by resonance, making it favorable for substitution reactions.
Examine the nucleophile: KCN (potassium cyanide) is a strong nucleophile. Strong nucleophiles typically favor SN2 mechanisms over SN1 mechanisms.
Consider the solvent: DMSO (dimethyl sulfoxide) is a polar aprotic solvent. Polar aprotic solvents stabilize the transition state of SN2 reactions and do not stabilize carbocations, making SN2 more likely than SN1.
Evaluate steric hindrance: The benzylic position is relatively unhindered, which is ideal for an SN2 reaction since SN2 requires a backside attack by the nucleophile.
Rule out elimination mechanisms: There is no strong base present, and the reaction conditions (strong nucleophile and polar aprotic solvent) are more suited for substitution rather than elimination. Therefore, E1 and E2 mechanisms are unlikely.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nucleophilic Substitution Mechanisms
Nucleophilic substitution reactions can occur via two primary mechanisms: S_N1 and S_N2. S_N1 reactions involve a two-step process where the leaving group departs first, forming a carbocation intermediate, followed by nucleophilic attack. In contrast, S_N2 reactions are single-step processes where the nucleophile attacks the substrate simultaneously as the leaving group departs, leading to a concerted mechanism.
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Nucleophiles and Electrophiles can react in Substitution Reactions.
Elimination Reactions
Elimination reactions can also occur through two mechanisms: E1 and E2. E1 reactions involve the formation of a carbocation intermediate after the leaving group departs, followed by deprotonation to form a double bond. E2 reactions are concerted, where the base abstracts a proton while the leaving group departs, resulting in the formation of a double bond in a single step.
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Factors Influencing Mechanism Choice
The choice between S_N1, S_N2, E1, and E2 mechanisms depends on several factors, including the structure of the substrate (primary, secondary, or tertiary), the strength and concentration of the nucleophile or base, and the solvent used. Polar protic solvents favor S_N1 and E1 mechanisms by stabilizing carbocations, while polar aprotic solvents favor S_N2 and E2 mechanisms by enhancing nucleophilicity.
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Related Practice
Textbook Question
Using an appropriate tosylate intermediate, synthesize the following molecules starting from the appropriate alcohol.
(b)
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Textbook Question
Using an appropriate tosylate intermediate, synthesize the following molecules starting from the appropriate alcohol.
(a)
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Textbook Question
Identify whether each of the following reactions proceed by an SN1 ,SN2 , E1, or E2 mechanism.
(a)
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Textbook Question
Predict the product for each of the following reactions.
(d)
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Textbook Question
Identify whether each of the following reactions proceed by an SN1, SN2, E1, or E2 mechanism.
(b)
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