Textbook Question
The following steps were used in the synthesis of the antimalarial thiaplakortone A. Identify the missing reagents, (a) and (b),
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Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring
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. 24 - Benzene II: Reactions Influenced by the Aromatic RingProblem 46
Mullins 1st EditionCh. 24 - Benzene II: Reactions Influenced by the Aromatic RingProblem 46Chapter 23, Problem 46
The following reaction proceeds in good yield, despite requiring high temperature and high concentration. Identify the product you’d expect to obtain in this reaction.
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Identify the reactants: The reaction involves phenol (C6H5OH) and gamma-butyrolactone (a cyclic ester).
Recognize the reaction type: This is similar to the Kolbe-Schmitt reaction, where phenol reacts with carbon dioxide in the presence of a base to form salicylic acid. Here, the base is potassium ethoxide (KOEt) in ethanol.
Understand the mechanism: The phenol will be deprotonated by the strong base (KOEt) to form phenoxide ion, which is a strong nucleophile.
Nucleophilic attack: The phenoxide ion will attack the carbonyl carbon of the gamma-butyrolactone, opening the lactone ring and forming a carboxylate intermediate.
Acidic quench: The reaction mixture is then quenched with an acid (H3O+), which will protonate the carboxylate to form the final carboxylic acid product.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nucleophilic Acyl Substitution
Nucleophilic acyl substitution is a fundamental reaction in organic chemistry where a nucleophile attacks a carbonyl carbon, leading to the substitution of a leaving group. In this case, the phenol (with -OH) acts as a nucleophile, attacking the carbonyl carbon of the cyclic anhydride. This reaction is crucial for forming esters or amides from carboxylic acids or their derivatives.
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Nucleophiles and Electrophiles can react in Substitution Reactions.
Role of Base in Reactions
In organic reactions, bases like KOEt (potassium ethoxide) are often used to deprotonate alcohols or phenols, enhancing their nucleophilicity. This step is essential for facilitating the nucleophilic attack on the carbonyl compound. The use of a strong base in this reaction indicates that the reaction may proceed more efficiently under high temperature and concentration conditions.
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02:43Recognizing Acid-Base Reactions.
Quenching Reactions
Quenching is a process used to stop a chemical reaction, typically by adding a reagent that neutralizes the reactive species. In this case, the addition of H3O+ after the reaction serves to protonate any remaining nucleophiles and stabilize the product. This step is crucial for ensuring that the desired product is obtained in a stable form and to prevent further reactions that could lead to side products.
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Related Practice
Textbook Question
The benzylic bromide shown undergoes neither SN1 nor SN2 substitution reactions. Explain.
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Textbook Question
In Chapter 13, we learned that epoxide opening can give different products, depending on whether the reaction occurs under acidic or basic conditions. Explain why the epoxide shown opens identically under either set of conditions.
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Textbook Question
In Chapter 23, we learned about the electrophilic aromatic nitration reaction. When phenol is subjected to these conditions with a large excess of nitric acid, a molecule called picric acid is produced. Predict the product of this reaction and explain why the pKa value of this compound is 0.38.
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Textbook Question
Beginning with benzene, synthesize the benzyl bromide shown.
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Textbook Question
Rationalize the fact that 1,4-dihydroxybenzene melts at a significantly higher temperature than 1,2-diydroxybenzene.
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