Textbook Question
What are the major 1,2- and 1,4-addition products of the following reaction? Indicate the kinetic and the thermodynamic products.
a.
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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 Benzene
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. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of BenzeneProblem 37b
Bruice 8th EditionCh. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of BenzeneProblem 37bChapter 9, Problem 37b
What are the major 1,2- and 1,4-addition products of the following reaction? Indicate the kinetic and the thermodynamic products.
b. 
Verified step by step guidance1
Step 1: Analyze the structure provided in the image. The molecule is a conjugated diene, specifically cyclopentadiene, which has two double bonds in conjugation. This makes it suitable for electrophilic addition reactions.
Step 2: Understand the reaction mechanism. In electrophilic addition reactions to conjugated dienes, the electrophile (e.g., H⁺) adds to one of the double bonds, forming a carbocation intermediate. The carbocation can then undergo resonance to form two different intermediates.
Step 3: Identify the possible products. The 1,2-addition product forms when the electrophile adds to one double bond and the nucleophile adds to the adjacent carbon. The 1,4-addition product forms when the electrophile adds to one double bond and the nucleophile adds to the carbon at the other end of the conjugated system.
Step 4: Distinguish between kinetic and thermodynamic control. The kinetic product is formed faster and typically involves the more stable carbocation intermediate. The thermodynamic product is more stable overall and forms under conditions that allow the reaction to reach equilibrium.
Step 5: Predict the major products. The 1,2-addition product is usually the kinetic product because it forms faster due to proximity of the nucleophile to the carbocation. The 1,4-addition product is typically the thermodynamic product because it results in a more substituted and stable double bond.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
1,2- and 1,4-Addition Reactions
1,2- and 1,4-addition reactions refer to the ways in which reagents can add to conjugated systems, such as alkenes. In 1,2-addition, the reagent adds to the first and second carbon atoms of the double bond, while in 1,4-addition, it adds to the first and fourth carbon atoms. These pathways lead to different products, which can have distinct stability and reactivity.
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Kinetic vs. Thermodynamic Products
Kinetic and thermodynamic products arise from different reaction conditions and pathways. Kinetic products are formed faster and are typically less stable, while thermodynamic products are more stable and form more slowly. Understanding the conditions that favor one over the other, such as temperature and reaction time, is crucial for predicting the outcome of addition reactions.
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Conjugated Systems
Conjugated systems consist of alternating single and double bonds, allowing for delocalization of electrons. This delocalization stabilizes the molecule and influences its reactivity. In the context of addition reactions, the presence of conjugation can affect the regioselectivity and the stability of the resulting products, making it essential to consider when analyzing reaction outcomes.
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Related Practice
Textbook Question
What are the products of the following reactions?
c.
Textbook Question
What is the major product when the methoxy substituent in the preceding reaction is bonded to C-2 of the diene rather than to C-1?
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Textbook Question
What are the products of the following reactions, assuming that one equivalent of each reagent is used in each reaction? Disregard stereoisomers.
b.
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Textbook Question
What are the products of the following reactions?
d.
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Textbook Question
A student wanted to know whether the greater proximity of the nucleophile to the C-2 carbon in the transition state is what causes the 1,2-addition product to be formed faster when 1,3-butadiene reacts with HCl. Therefore, she decided to investigate the reaction of 2-methyl-1,3-cyclohexadiene with HCl. Her friend told her that she should use 1-methyl-1,3-cyclohexadiene instead. Should she follow her friend's advice?
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