Textbook Question
Predict the product of the Diels–Alder reactions shown.
(a)
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Ch. 22 - Conjugated Systems II: Pericyclic Reactions
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
Chapter 21, Problem 34e
Identify the following dienes as being in the s-cis or s-trans conformation. If they are in the s-trans conformation, draw them in the s-cis conformation. [It may not always be possible.]
(e) 
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Understand the concept of s-cis and s-trans conformations: In conjugated dienes, the single bond between the two double bonds can rotate, allowing the molecule to adopt different conformations. The s-cis conformation has both double bonds on the same side of the single bond, while the s-trans conformation has them on opposite sides.
Examine the structure of the diene: Look at the arrangement of the double bonds relative to the single bond connecting them. Identify if the double bonds are on the same side (s-cis) or opposite sides (s-trans).
Determine the current conformation: Based on the arrangement, decide if the diene is currently in the s-cis or s-trans conformation.
If the diene is in the s-trans conformation, attempt to visualize or draw it in the s-cis conformation: Rotate the single bond to bring the double bonds to the same side. Note that steric hindrance or other structural constraints may prevent this rotation.
Consider the implications of the conformation: The s-cis conformation is often more reactive in certain reactions, such as Diels-Alder reactions, due to the proximity of the double bonds. Understanding the conformation can help predict reactivity and stability.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Diene Conformation
Dienes are hydrocarbons with two double bonds. Their conformation refers to the spatial arrangement of these double bonds. The s-cis conformation has the double bonds on the same side of the single bond connecting them, while the s-trans conformation has them on opposite sides. Understanding these conformations is crucial for predicting the reactivity and stability of dienes.
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Understanding what a conformer is.
Steric Hindrance
Steric hindrance occurs when the size of groups within a molecule prevents chemical reactions that are otherwise possible. In the context of dienes, steric hindrance can influence whether a diene can adopt an s-cis conformation, as bulky groups may prevent the necessary rotation around the single bond, making the s-trans conformation more stable.
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Molecular Rotation
Molecular rotation refers to the ability of parts of a molecule to rotate around single bonds. This rotation is essential for converting between s-cis and s-trans conformations in dienes. However, rotation can be restricted by factors such as steric hindrance or the presence of rings, which can lock the molecule in a specific conformation.
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Related Practice
Textbook Question
Provide a mechanism of the Diels–Alder reaction shown and predict the regioisomer that will form.
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Textbook Question
Predict the product of the following sigmatropic rearrangements. Be sure to rationalize the stereochemical outcome with a chair-like transition state.
(b)
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Textbook Question
Predict the product of the following sigmatropic rearrangements. Be sure to rationalize the stereochemical outcome with a chair-like transition state.
(d)
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Textbook Question
Identify the following dienes as being in the s-cis or s-trans conformation. If they are in the s-trans conformation, draw them in the s-cis conformation. [It may not always be possible.]
(c)
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Textbook Question
For the following electrocyclic reactions, did the substituents move in a conrotatory or disrotatory direction? Would you use heat or light to cause movement in this direction?
(a)
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