Textbook Question
What are the products of the following reactions? Show all stereoisomers that are formed.
c.
d.
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Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
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Bruice 8th EditionCh. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid DerivativesProblem 75a,b
Bruice 8th EditionCh. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid DerivativesProblem 75a,bChapter 17, Problem 75a,b
What product is formed when 3-methyl-2-cyclohexenone reacts with each of the following reagents?
a. CH3MgBr followed by H3O+
b. (CH3CH2)2CuLi followed by H3O+
Verified step by step guidance1
Step 1: Analyze the structure of 3-methyl-2-cyclohexenone. It is a conjugated enone, meaning it has both a carbonyl group (C=O) and a double bond in conjugation. This makes it susceptible to both nucleophilic addition at the carbonyl carbon and conjugate (1,4) addition at the β-carbon of the double bond.
Step 2: For part (a), CH3MgBr is a Grignard reagent, which is a strong nucleophile. Grignard reagents typically perform nucleophilic addition to the carbonyl carbon (1,2-addition). The CH3 group from CH3MgBr will attack the carbonyl carbon, breaking the C=O double bond and forming an alkoxide intermediate. Upon protonation with H3O+, the alkoxide is converted into an alcohol.
Step 3: For part (b), (CH3CH2)2CuLi is a Gilman reagent, which is a softer nucleophile. Gilman reagents preferentially perform conjugate (1,4) addition to α,β-unsaturated carbonyl compounds. The ethyl group (CH3CH2) will add to the β-carbon of the conjugated double bond, shifting the double bond and leaving the carbonyl group intact. Protonation with H3O+ completes the reaction.
Step 4: Draw the product for part (a). After the 1,2-addition of CH3MgBr and subsequent protonation, the product will have a new CH3 group attached to the former carbonyl carbon, and the carbonyl group will be converted into an alcohol.
Step 5: Draw the product for part (b). After the 1,4-addition of (CH3CH2)2CuLi and subsequent protonation, the product will have a new CH2CH3 group attached to the β-carbon of the conjugated system, with the carbonyl group remaining intact.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nucleophilic Addition
Nucleophilic addition is a fundamental reaction in organic chemistry where a nucleophile attacks an electrophilic carbon atom, typically in a carbonyl group. In the case of 3-methyl-2-cyclohexenone, the carbonyl carbon is susceptible to nucleophilic attack, leading to the formation of an alcohol after subsequent protonation. Understanding this mechanism is crucial for predicting the products of reactions with reagents like Grignard reagents and organocuprates.
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Nucleophilic Addition
Grignard Reagents
Grignard reagents, such as CH3MgBr, are highly reactive organomagnesium compounds that act as strong nucleophiles. They can add to carbonyl compounds, forming a new carbon-carbon bond. After the addition, hydrolysis with H3O+ converts the intermediate alkoxide into an alcohol. Recognizing the reactivity and behavior of Grignard reagents is essential for determining the outcome of the reaction with 3-methyl-2-cyclohexenone.
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Organocuprates
Organocuprates, like (CH3CH2)2CuLi, are less reactive than Grignard reagents but still serve as nucleophiles in organic reactions. They can add to carbonyl compounds, leading to the formation of ketones or aldehydes, depending on the structure of the starting material. Understanding the unique properties and selectivity of organocuprates is important for predicting the products formed when they react with compounds like 3-methyl-2-cyclohexenone.
Related Practice
Textbook Question
List three different sets of reagents (each set consisting of a carbonyl compound and a Grignard reagent) that could be used to prepare each of the following tertiary alcohols:
b.
915
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Textbook Question
What product is formed when 3-methyl-2-cyclohexenone reacts with each of the following reagents?
c. HBr
d. CH3CH2SH
1058
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Textbook Question
Propose a mechanism for each of the following reactions:
a.
1241
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Textbook Question
List three different sets of reagents (each set consisting of a carbonyl compound and a Grignard reagent) that could be used to prepare each of the following tertiary alcohols:
a.
1213
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Textbook Question
What is the product of each of the following reactions?
c.
d.
1099
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