Domanda del libro di testo
Ozonolysis of an unknown alkene A gives the products shown. Predict the product that results from hydrogenation of alkene A. [There are multiple answers, but only show the one with the 6-membered ring.]
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Ch. 9 - Alkenes 2: Oxidation and Reduction
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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TOC.tableOfContents
- 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 1: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes 2: 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 1: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification 2: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution 1: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution 2: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems 1: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems 2: Pericyclic Reactions54
- Ch. 23 - Benzene 1: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene 2: 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: 9780137566471Non è quello che usi tu?Cambia libro di testo
Capitolo 8, Problema 54
In Chapter 19, we discuss the reaction of enols with bromine. This reaction produces α -bromoketones in good yields. Suggest a mechanism for this reaction and justify its deviation from the dibromide product you might have expected.
Guida verificata passo dopo passo1
Step 1: Recognize that the reaction involves enols reacting with bromine (Br₂) to form α-bromoketones. The enol tautomer is the reactive intermediate in this process, and the reaction proceeds via electrophilic halogenation.
Step 2: Understand the mechanism begins with the enol donating electrons from its double bond to bromine (Br₂), forming a bromonium ion intermediate. This step is driven by the nucleophilicity of the enol's double bond.
Step 3: The bromonium ion is then attacked by water or another nucleophile, leading to the formation of a hydroxyl group and a bromine atom on the α-carbon. This intermediate is unstable and undergoes further transformation.
Step 4: The hydroxyl group on the α-carbon is eliminated as water, resulting in the formation of a carbonyl group (ketone). This step explains why the final product is an α-bromoketone rather than a dibromide.
Step 5: The deviation from the dibromide product occurs because the reaction mechanism favors the formation of a stable carbonyl group over the addition of a second bromine atom. The reaction stops at the α-bromoketone stage due to the stability of the ketone product.
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Concetti chiave
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Enol Tautomerization
Enols are the keto-enol tautomer of carbonyl compounds, where the enol form contains a hydroxyl group bonded to a carbon-carbon double bond. Understanding enol tautomerization is crucial because the reaction with bromine involves the enol form, which is more reactive than the keto form. This process highlights the dynamic equilibrium between the two forms and the conditions that favor one over the other.
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05:11
Tautomerization Mechanisms
Electrophilic Addition
Electrophilic addition is a fundamental reaction mechanism in organic chemistry where an electrophile reacts with a nucleophile, resulting in the formation of a new bond. In the case of enols reacting with bromine, the double bond of the enol acts as a nucleophile, attacking the electrophilic bromine molecule. This step is essential for understanding how α-bromoketones are formed instead of the expected dibromide product.
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09:231,2 vs 1,4 Addition
Regioselectivity
Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In the reaction of enols with bromine, the regioselectivity is influenced by the stability of the resulting intermediates and products. This concept helps explain why the reaction favors the formation of α-bromoketones rather than a dibrominated product, as the more stable product is formed preferentially.
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Pratica correlata
Domanda del libro di testo
Consider the Cope rearrangement, a reaction we describe in Chapter 20.
(a) Using the knowledge we have gained here in Chapter 9, suggest a one-step, concerted mechanism that explains the formation of B from A.
(b) Which side of the reaction would you expect to be favored? Justify your answer.
(c) Which product, A or B, would you expect to be hydrogenated with the more exothermic heat of hydrogenation?
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Domanda del libro di testo
Bromination of a highly electron-rich alkene such as 2-methoxybut-2-ene has been shown to produce approximately equal mixtures of the trans- and cis-dibromide. Suggest an explanation for this observation.
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Domanda del libro di testo
In spite of being mechanistically similar to some of the reactions we saw in Chapter 8, rearrangement never occurred here in Chapter 9. Why doesn't rearrangement occur in the following bromination reaction despite the proximity of a more substituted carbon?
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Domanda del libro di testo
Predict the product of ozonolysis of the triglyceride shown.
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Domanda del libro di testo
Bromination of buta-1,3-diene with a single equivalent of Br2 can give either of two products. (a) Which of these products (A or B) would you predict to be more stable? Justify your answer.
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