Textbook Question
Predict the product of each of the following reactions.
(b)
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Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids
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
Chapter 26, Problem 36
Ketohexoses form from aldohexoses. Suggest a mechanism for the acid-catalyzed version of this reaction. What type of reaction is this? [You’ve seen it before.]
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Identify the starting aldohexose and the resulting ketohexose. The starting compound is an aldohexose with an aldehyde group at the top, and the product is a ketohexose with a ketone group on the second carbon.
Recognize that the reaction involves an isomerization process where the aldehyde group is converted into a ketone group. This is a type of tautomerization reaction known as an aldose-ketose isomerization.
In the presence of an acid catalyst (H3O+), the reaction begins with the protonation of the carbonyl oxygen of the aldehyde group, increasing its electrophilicity.
A hydride shift occurs where a hydrogen atom from the adjacent carbon (C2) migrates to the carbonyl carbon, forming a carbocation at C2. This step is crucial for the rearrangement of the carbonyl group.
Finally, deprotonation of the hydroxyl group at C2 leads to the formation of the ketone group, completing the conversion from an aldohexose to a ketohexose.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Aldohexoses and Ketohexoses
Aldohexoses are six-carbon sugars with an aldehyde group, while ketohexoses contain a ketone group. The conversion from aldohexoses to ketohexoses involves the rearrangement of functional groups, specifically the migration of the carbonyl group from the end of the chain to an internal position. This transformation is crucial in carbohydrate chemistry and is often seen in metabolic pathways.
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Which aldohexoses produce the same Wohl Degradation product
Acid-Catalyzed Reactions
Acid-catalyzed reactions involve the use of an acid to increase the rate of a chemical reaction. In the context of converting aldohexoses to ketohexoses, the acid protonates the carbonyl oxygen, making it more electrophilic and facilitating the rearrangement. This type of catalysis is common in organic reactions, particularly in carbohydrate chemistry, where protonation can stabilize intermediates.
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Rearrangement Reactions
Rearrangement reactions involve the structural reorganization of a molecule, leading to the formation of isomers. In the case of aldohexoses converting to ketohexoses, the reaction is a type of rearrangement where the carbon skeleton is altered. This process is significant in organic synthesis and biochemistry, as it allows for the interconversion of different sugar forms, impacting their biological functions.
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Related Practice
Textbook Question
In each of the disaccharides shown (a–c), (i) identify the reducing end of the sugar, (ii) tell what monosaccharides are used to make it, and (iii) tell what type of glycoside linkage is present.
(a)
Textbook Question
Maltose, like cellobiose, is composed of two glucose units. What is the difference between maltose and cellobiose?
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Textbook Question
Predict the product of each of the following reactions.
(d)
Textbook Question
In each of the disaccharides shown (a–c), (i) identify the reducing end of the sugar, (ii) tell what monosaccharides are used to make it, and (iii) tell what type of glycoside linkage is present.
(b)
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Textbook Question
Predict the product of each of the following reactions.
(c)
1
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