Textbook Question
Draw the product of each of the following reactions:
e.
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Ch. 28 - Pericyclic Reactions
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
Chapter 25, Problem 36
Propose a mechanism for the following reaction:
Verified step by step guidance1
Step 1: Analyze the reactants and products. The reactants include a nitro-substituted pyridine and an ester with two carbonyl groups. The products are a substituted pyridine derivative (A) and a carboxylic acid (B). This suggests a nucleophilic acyl substitution mechanism.
Step 2: Identify the reactive sites. The nitro group on the pyridine ring is electron-withdrawing, making the pyridine ring more electrophilic. The ester contains two carbonyl groups, which are susceptible to nucleophilic attack.
Step 3: Initiate the reaction mechanism. Heat (Δ) facilitates the reaction. The pyridine nitrogen acts as a nucleophile and attacks the carbonyl carbon of the ester, forming a tetrahedral intermediate.
Step 4: Collapse of the tetrahedral intermediate. The intermediate collapses, expelling the ethoxide group (CH₂CH₃O⁻) and forming a new bond between the pyridine nitrogen and the carbonyl carbon. This results in the formation of product A.
Step 5: Formation of product B. The expelled ethoxide group reacts with a proton to form ethanol (CH₃CH₂OH), which subsequently oxidizes to form the carboxylic acid product B.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Electrocyclic Reactions
Electrocyclic reactions are a class of pericyclic reactions where a conjugated system undergoes a concerted transformation to form a cyclic compound. These reactions are characterized by the rotation of a sigma bond and the formation or breaking of pi bonds, often influenced by thermal or photochemical conditions. Understanding the stereochemistry and the rules governing these reactions, such as the Woodward-Hoffmann rules, is crucial for predicting the products.
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Predicting Electrocyclic Products
Mechanism of Reaction
The mechanism of a reaction describes the step-by-step process by which reactants are converted into products. It includes the identification of intermediates, transition states, and the sequence of bond-breaking and bond-forming events. Proposing a mechanism requires knowledge of reaction conditions, the stability of intermediates, and the energy changes involved, which are essential for understanding how the reaction proceeds.
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Thermal Conditions in Organic Reactions
Thermal conditions refer to the influence of heat on the rate and outcome of chemical reactions. In organic chemistry, heating can provide the necessary energy to overcome activation barriers, facilitating reactions such as electrocyclic transformations. The temperature can also affect the selectivity and stereochemistry of the products, making it important to consider when proposing mechanisms for reactions that involve heat.
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Related Practice
Textbook Question
Draw the product of each of the following sigmatropic rearrangements:
d.
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Textbook Question
If the compounds shown here are heated, one will form one product from a [1,3] sigmatropic rearrangement and the other will form two products from two different [1,3] sigmatropic rearrangements. Draw the products of the reactions.
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Textbook Question
What is the product of the following [1,3] sigmatropic rearrangement, A or B?
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Textbook Question
b. What would be the product if trans-2-butene were used instead of ethene?
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Textbook Question
Draw the product of each of the following sigmatropic rearrangements:
c.
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