Textbook Question
Dichlorocarbene can also be generated by heating sodium trichloroacetate. Propose a mechanism for the reaction.
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Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition 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
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Bruice 8th EditionCh. 6 - The Reactions of Alkenes • The Stereochemistry of Addition ReactionsProblem 91
Bruice 8th EditionCh. 6 - The Reactions of Alkenes • The Stereochemistry of Addition ReactionsProblem 91Chapter 7, Problem 91
Two chemists at Dupont found that ICH2ZnI is better than diazomethane at converting a C=C bond to a cylcopropane ring. Propose a mechanism for the reaction, now known as the Simmons–Smith reaction in their honor.
Verified step by step guidance1
Step 1: Recognize that the Simmons–Smith reaction involves the conversion of an alkene (C=C bond) into a cyclopropane ring using the reagent ICH2ZnI. This reagent acts as a carbenoid, which is a species that mimics the reactivity of a carbene.
Step 2: Understand the role of ICH2ZnI. The reagent is formed by the reaction of diiodomethane (ICH2I) with a zinc-copper couple. The zinc stabilizes the carbenoid intermediate, making it reactive toward the alkene.
Step 3: Propose the mechanism. The carbenoid (ICH2ZnI) approaches the alkene, and the zinc coordinates with the π-electrons of the double bond. This interaction facilitates the transfer of the CH2 group to the alkene.
Step 4: Describe the cyclopropanation step. The CH2 group inserts into the double bond of the alkene, forming a three-membered cyclopropane ring. This occurs via a concerted mechanism, where bonds are broken and formed simultaneously.
Step 5: Highlight the stereochemical implications. The Simmons–Smith reaction typically preserves the stereochemistry of the alkene, meaning that the substituents on the original double bond will determine the stereochemistry of the cyclopropane ring.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Simmons-Smith Reaction
The Simmons-Smith reaction is a chemical reaction that converts alkenes into cyclopropanes using a reagent composed of diiodomethane (ICH2I) and zinc. This reaction is notable for its ability to form cyclopropane rings in a stereospecific manner, preserving the configuration of the starting alkene. The reaction proceeds through a carbenoid intermediate, which facilitates the addition of the methylene group across the double bond.
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The Simmons-Smith reaction.
Carbenoid Intermediates
Carbenoid intermediates are reactive species that resemble carbenes but are stabilized by metal complexes, such as zinc in the Simmons-Smith reaction. These intermediates can participate in various reactions, including cyclopropanation, by inserting into double bonds. The presence of a carbenoid allows for the formation of new carbon-carbon bonds while maintaining the integrity of the original alkene structure.
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Mechanism of Cyclopropanation
The mechanism of cyclopropanation involves the addition of a carbenoid to an alkene, resulting in the formation of a three-membered cyclopropane ring. Initially, the alkene attacks the carbenoid, leading to a transition state that ultimately collapses to form the cyclopropane. This process is characterized by a concerted mechanism, where bond formation and breaking occur simultaneously, ensuring that the stereochemistry of the alkene is retained in the product.
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Related Practice
Textbook Question
What alkene gives the product shown after reaction first with ozone and then with dimethyl sulfide?
b.
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Textbook Question
The reaction of an alkene with diazomethane forms a cyclopropane ring. Propose a mechanism for the reaction. (Hint: It is a concerted reaction.)
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Textbook Question
What alkene gives the product shown after reaction first with ozone and then with dimethyl sulfide?
a.
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Textbook Question
A, a compound with molecular formula C6H10, contains three methylene units. A reacts with one equivalent of H2 over Pd/C to yield B. A reacts with aqueous acid to form a single product, C, and undergoes hydroboration/oxidation to form a pair of enantiomers, D and E. Ozonolysis of A followed by reaction with dimethyl sulfide forms F with molecular formula C6H10O2. Provide structures for A–F.
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Textbook Question
Of the possible products shown for the following reaction, are there any that will not be formed?
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