Textbook Question
Propose a mechanism for each of the following reactions:
a.
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Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives
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. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid DerivativesProblem 87
Bruice 8th EditionCh. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid DerivativesProblem 87Chapter 17, Problem 87
Shown below is the 1H NMR spectrum of the alkyl bromide used to make the phosphonium ylide that reacts with a ketone in a Wittig reaction to form a compound with molecular formula C11H14. What product is obtained from the Wittig reaction?
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Analyze the molecular formula (C11H14) of the product to determine the degree of unsaturation. Use the formula: Degree of Unsaturation = (2C + 2 - H - X + N)/2, where C = number of carbons, H = number of hydrogens, X = number of halogens, and N = number of nitrogens.
Understand the Wittig reaction mechanism: A phosphonium ylide reacts with a ketone to form an alkene. The product will have a new carbon-carbon double bond formed between the carbon of the ylide and the carbonyl carbon of the ketone.
Examine the 1H NMR spectrum of the alkyl bromide to deduce its structure. Look for key signals such as chemical shifts, splitting patterns, and integration values to identify the alkyl bromide precursor used to generate the phosphonium ylide.
Combine the structure of the phosphonium ylide (derived from the alkyl bromide) with the ketone reactant. Identify the carbonyl group in the ketone and determine where the new double bond will form in the product.
Draw the structure of the product, ensuring that the molecular formula matches C11H14. Confirm that the product contains the correct number of carbons, hydrogens, and the expected degree of unsaturation (likely an alkene).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
NMR Spectroscopy
Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful analytical technique used to determine the structure of organic compounds. It provides information about the number of hydrogen atoms in different environments within a molecule, allowing chemists to deduce connectivity and functional groups. In this context, interpreting the 1H NMR spectrum helps identify the alkyl bromide's structure, which is crucial for understanding the subsequent Wittig reaction.
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General NMR Features
Wittig Reaction
The Wittig reaction is a chemical reaction that involves the reaction of a phosphonium ylide with a carbonyl compound, such as a ketone, to form an alkene. This reaction is significant in organic synthesis for constructing double bonds in a controlled manner. Understanding the mechanism and the role of the ylide is essential for predicting the product formed from the reaction with the ketone.
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Molecular Formula and Product Prediction
The molecular formula of a compound provides insight into its composition and can help predict the structure of the product formed in a reaction. In this case, the molecular formula C11H14 indicates a specific number of carbon and hydrogen atoms, guiding the identification of possible alkenes resulting from the Wittig reaction. Analyzing the molecular formula alongside the starting materials allows for accurate product prediction.
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Related Practice
Textbook Question
In the presence of an acid catalyst, acetaldehyde forms a trimer known as paraldehyde. Because it induces sleep when it is administered to animals in large doses, paraldehyde is used as a sedative or hypnotic. Propose a mechanism for the formation of paraldehyde.
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Textbook Question
In an aqueous solution, D-glucose exists in equilibrium with two six-membered ring compounds. Draw the structures of these compounds.
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Textbook Question
What carbonyl compound and what phosphonium ylide are needed to synthesize the following compounds?
b.
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Textbook Question
Identify compounds A and B:
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Textbook Question
Propose a mechanism for each of the following reactions:
b.
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