Textbook Question
Show how you would accomplish the following syntheses efficiently (you may use any necessary reagents).
(g)
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Ch. 20 - Carboxylic Acids
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 20, Problem 37b
Predict the products and propose mechanisms for the following reactions.
(b) 
Verified step by step guidance1
Step 1: Analyze the reactant structure. The given compound is an ester, specifically methyl benzoate, which contains a benzene ring attached to a carboxylic acid ester functional group (-COOCH3). The reaction conditions involve hydroxide ions (OH⁻) in water, indicating a base-catalyzed hydrolysis reaction.
Step 2: Understand the reaction mechanism. Base-catalyzed hydrolysis of esters proceeds through nucleophilic attack by the hydroxide ion (OH⁻) on the carbonyl carbon of the ester group. This forms a tetrahedral intermediate.
Step 3: Break down the intermediate. The tetrahedral intermediate collapses, leading to the cleavage of the ester bond. The methoxide ion (CH3O⁻) is expelled as a leaving group, and a carboxylate ion (-COO⁻) is formed.
Step 4: Finalize the product formation. In the aqueous environment, the carboxylate ion reacts with water to form benzoic acid (C6H5COOH) as the final product. The methoxide ion (CH3O⁻) may also react with water to form methanol (CH3OH).
Step 5: Summarize the reaction. The base-catalyzed hydrolysis of methyl benzoate under OH⁻/H2O conditions results in the formation of benzoic acid and methanol as the products.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Saponification
Saponification is a chemical reaction that involves the hydrolysis of esters in the presence of a strong base, typically sodium hydroxide (NaOH) or potassium hydroxide (KOH). In this process, an ester reacts with hydroxide ions to produce an alcohol and a carboxylate salt. This reaction is commonly associated with the production of soap from fats and oils, where the ester bonds are broken down to yield fatty acid salts.
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Mechanism
Mechanism of Nucleophilic Substitution
The mechanism of nucleophilic substitution involves the attack of a nucleophile on an electrophilic carbon atom, leading to the displacement of a leaving group. In the case of saponification, the hydroxide ion acts as the nucleophile, attacking the carbonyl carbon of the ester. This results in the formation of a tetrahedral intermediate, which subsequently collapses to release the alcohol and form the carboxylate ion.
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Role of Hydroxide Ion
The hydroxide ion (OH-) plays a crucial role in saponification as a strong nucleophile that initiates the reaction. Its high electron density allows it to effectively attack the electrophilic carbon of the ester, facilitating the cleavage of the ester bond. The presence of water in the reaction medium also aids in the hydrolysis process, ensuring that the products are formed efficiently and that the reaction reaches completion.
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Related Practice
Textbook Question
Predict the products and propose mechanisms for the following reactions.
(d)
1044
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Textbook Question
Show how you would accomplish the following syntheses efficiently (you may use any necessary reagents).
(h)
526
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Textbook Question
When pure (S)-lactic acid is esterified by racemic butan-2-ol, the product is 2-butyl lactate, with the following structure:
(a) Draw three-dimensional structures of the two stereoisomers formed, specifying the configuration at each asymmetric carbon atom. (Using your models may be helpful.)
(b) Determine the relationship between the two stereoisomers you have drawn
895
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Textbook Question
Predict the products and propose mechanisms for the following reactions.
(c)
1295
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Textbook Question
Predict the products and propose mechanisms for the following reactions.
(a)
865
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