Textbook Question
Show the electronic configuration of the ground state of hexa-1,3,5-triene.
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Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy
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
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Wade 9th EditionCh. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet SpectroscopyProblem 36e
Wade 9th EditionCh. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet SpectroscopyProblem 36eChapter 15, Problem 36e
Show the Diels–Alder product that would actually result from heating hexa-1,3,5-triene with maleic anhydride.
Verified step by step guidance1
Step 1: Recognize that the Diels–Alder reaction involves a conjugated diene (hexa-1,3,5-triene) and a dienophile (maleic anhydride). The diene must adopt an s-cis conformation to participate in the reaction.
Step 2: Analyze the structure of hexa-1,3,5-triene. It contains three conjugated double bonds, and the central double bond allows rotation to achieve the s-cis conformation necessary for the reaction.
Step 3: Identify maleic anhydride as the dienophile. It contains a highly electron-deficient double bond due to the electron-withdrawing carbonyl groups, making it reactive toward the diene.
Step 4: Predict the cycloaddition mechanism. The diene and dienophile undergo a [4+2] cycloaddition, forming a six-membered ring. The new bonds are formed between the terminal carbons of the diene and the carbons of the dienophile's double bond.
Step 5: Consider the stereochemistry of the product. Maleic anhydride is symmetric, so the product will have the anhydride functional group attached to the six-membered ring. The reaction is stereospecific, resulting in a single stereoisomer.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Diels–Alder Reaction
The Diels–Alder reaction is a [4+2] cycloaddition between a conjugated diene and a dienophile, resulting in the formation of a six-membered ring. This reaction is thermally allowed and is characterized by the formation of new sigma bonds while maintaining the integrity of the pi systems. Understanding the stereochemistry and regioselectivity of this reaction is crucial for predicting the product.
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Diels-Alder Retrosynthesis
Conjugated Dienes
Conjugated dienes are compounds that contain two double bonds separated by a single bond, allowing for resonance stabilization. In the context of the Diels–Alder reaction, the diene must be in an s-cis conformation to effectively overlap with the dienophile. Recognizing the structure and reactivity of conjugated dienes is essential for predicting the outcome of the reaction.
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Dienophile
A dienophile is a compound that contains a double or triple bond and reacts with a diene in the Diels–Alder reaction. Maleic anhydride, a common dienophile, is electron-deficient, which enhances its reactivity towards electron-rich dienes like hexa-1,3,5-triene. Understanding the nature of the dienophile helps in predicting the regioselectivity and stereochemistry of the Diels–Alder product.
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Related Practice
Textbook Question
The pentadienyl radical, H2C=CH–CH=CH–CH2•, has its unpaired electron delocalized over three carbon atoms.
b. How many MOs are there in the molecular orbital picture of the pentadienyl radical?
c. How many nodes are there in the lowest-energy MO of the pentadienyl system? How many in the highest-energy MO?
d. Draw the MOs of the pentadienyl system in order of increasing energy
Textbook Question
Show that the [6 + 2] cyclization of hexa-1,3,5-triene with maleic anhydride is thermally forbidden but photochemically allowed.
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Textbook Question
The pentadienyl radical, H2C=CH–CH=CH–CH2•, has its unpaired electron delocalized over three carbon atoms.
f. Show how your molecular orbital picture agrees with the resonance picture showing delocalization of the unpaired electron onto three carbon atoms.
Textbook Question
The pentadienyl radical, H2C=CH–CH=CH–CH2•, has its unpaired electron delocalized over three carbon atoms.
a. Use resonance forms to show which three carbon atoms bear the unpaired electron.
Textbook Question
Show what product would result from the [6 + 2] cycloaddition of hexa-1,3,5-triene with maleic anhydride.
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