Textbook Question
Chapter 8 discussed the synthesis of cholesterol, which proceeds by a cationic cyclization cascade. Without looking back, suggest a mechanism by which the following reaction occurs. [The carbons have been numbered for you.]
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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 118
Mullins 1st EditionCh. 13 - Alcohols, Ethers and Related Compounds: Substitution and EliminationProblem 118Chapter 12, Problem 118
Assessment 8.74 revealed that oxymercuration could be used to make cyclic esters. Suggest a likely mechanism for this transformation.
Verified step by step guidance1
Step 1: Begin by understanding the oxymercuration reaction. Oxymercuration involves the addition of mercuric acetate (Hg(OAc)₂) to an alkene, forming a mercurinium ion intermediate.
Step 2: Analyze the structure of the starting material. The molecule contains an alkene and a hydroxyl group. The alkene is the site of the oxymercuration reaction.
Step 3: Consider the formation of the mercurinium ion. The alkene undergoes electrophilic addition with Hg(OAc)₂, forming a cyclic mercurinium ion. This intermediate is crucial for the subsequent steps.
Step 4: Examine the role of the hydroxyl group. The hydroxyl group can act as a nucleophile, attacking the mercurinium ion. This intramolecular attack leads to the formation of a cyclic ester.
Step 5: Complete the reaction with NaBH₄. Sodium borohydride (NaBH₄) is used to reduce the mercury-containing intermediate, replacing the mercury with a hydrogen atom, finalizing the formation of the cyclic ester.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Oxymercuration-Demercuration
Oxymercuration is a reaction that involves the addition of mercuric acetate to an alkene, forming a mercurial intermediate. This process typically leads to the formation of alcohols through nucleophilic attack by water. The subsequent demercuration step replaces the mercury with a hydrogen atom, resulting in an alcohol product. Understanding this mechanism is crucial for predicting how cyclic esters can be formed from alkenes.
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General properties of oxymercuration-reduction.
Cyclic Esters (Lactones)
Cyclic esters, also known as lactones, are formed when a hydroxy acid undergoes intramolecular esterification. This process involves the reaction of a hydroxyl group with a carboxylic acid group within the same molecule, leading to the formation of a ring structure. Recognizing the conditions under which cyclic esters can form is essential for proposing a mechanism involving oxymercuration.
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Mechanistic Pathways in Organic Reactions
Understanding mechanistic pathways is vital in organic chemistry as it describes the step-by-step sequence of events that occur during a chemical reaction. This includes identifying intermediates, transition states, and the role of catalysts. In the context of oxymercuration leading to cyclic esters, a clear grasp of these pathways will help in suggesting a plausible mechanism for the transformation.
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Related Practice
Textbook Question
The acid-catalyzed dehydration we learned in this chapter is reversible, as shown below.
(b) Without looking back, how do you know this mechanism is correct?
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Textbook Question
The acid-catalyzed dehydration we learned in this chapter is reversible, as shown below.
(c) Which side of the reaction would be favored by running the reaction at low temperatures?
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Textbook Question
The acid-catalyzed dehydration we learned in this chapter is reversible, as shown below.
(d) How might you shift the equilibrium to the right?
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Textbook Question
Suggest reagents to carry out the following transformation.