Textbook Question
Provide a mechanism for the formation of the hemiacetals shown. [Only (c) is favored as written.]
(a)
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Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones
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
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Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 51a
Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 51aChapter 16, Problem 51a
Show the product expected by the Wolff–Kishner reduction of the following aldehydes/ketones.
(a)
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Identify the functional group in the given compound that will undergo the Wolff–Kishner reduction. In this case, it is the carbonyl group (C=O) of the ketone.
Understand that the Wolff–Kishner reduction is a method used to convert carbonyl groups into methylene groups (CH2) using hydrazine (H2NNH2) and a strong base like KOH under high temperature.
Recognize that the reaction involves the formation of a hydrazone intermediate, where the carbonyl oxygen is replaced by a hydrazine moiety, followed by the elimination of nitrogen gas (N2) to form the alkane.
Apply the Wolff–Kishner reduction to the given ketone. Replace the carbonyl group with a methylene group, effectively removing the oxygen and adding two hydrogen atoms to the carbonyl carbon.
Draw the final product structure, ensuring that the pyridine ring and the ethyl group remain unchanged, while the carbonyl carbon is now part of a methylene group, resulting in a fully saturated carbon chain.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Wolff–Kishner Reduction
The Wolff–Kishner reduction is a chemical reaction used to convert carbonyl compounds, such as aldehydes and ketones, into alkanes. This process involves the hydrazone formation followed by the treatment with a strong base, typically potassium hydroxide, and heating, which leads to the removal of nitrogen gas and the formation of the corresponding alkane.
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Mechanism
Carbonyl Compounds
Carbonyl compounds are organic molecules that contain a carbon atom double-bonded to an oxygen atom (C=O). This functional group is characteristic of aldehydes and ketones, which differ in their structure; aldehydes have at least one hydrogen atom attached to the carbonyl carbon, while ketones have two carbon groups attached. Understanding their structure is crucial for predicting the outcome of reactions like the Wolff–Kishner reduction.
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Hydrazones
Hydrazones are compounds formed by the reaction of hydrazine with carbonyl compounds, resulting in a C=N bond. In the context of the Wolff–Kishner reduction, the formation of a hydrazone intermediate is essential, as it stabilizes the carbonyl compound and facilitates the subsequent elimination of nitrogen gas, ultimately leading to the formation of the alkane product.
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Related Practice
Textbook Question
The following molecules were named incorrectly according to IUPAC nomenclature. Give the correct name of these compounds.
b. (R)-6-bromo-7-oxoheptan-2-one
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Textbook Question
During an oxidation reaction, there must also be a reduction. What is reduced in the Pinnick oxidation?
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Textbook Question
Identify the hemiacetal functional group in each of the following molecules. These molecules may not be stable enough to be the favorable product in an equilibrium reaction.
(c)
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Textbook Question
The following molecules were named incorrectly according to IUPAC nomenclature. Give the correct name of these compounds.
(a) 3-oxo-5-methylhexan-2-ol
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Textbook Question
Which of the following cyclic hemiacetals would you expect to have the highest Keq for their formation? Explain your answer.
(a)
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