Textbook Question
What sugar is the C-3 epimer of D-fructose?
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Ch. 20 - The Organic Chemistry of Carbohydrates
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 21, Problem 5d
d. What sugar is the C-4 epimer of D-lyxose?
Verified step by step guidance1
Understand the concept of epimers: Epimers are stereoisomers that differ in the configuration of only one stereogenic center (chiral carbon) while the rest of the molecule remains the same. In this case, we are looking for the C-4 epimer of D-lyxose.
Draw the Fischer projection of D-lyxose: D-lyxose is an aldopentose (a five-carbon sugar with an aldehyde group). Its configuration is as follows: the hydroxyl (-OH) groups on carbons 2, 3, and 4 are arranged as right, left, and left, respectively, in the Fischer projection.
Identify the C-4 carbon: In the Fischer projection of D-lyxose, the C-4 carbon is the fourth carbon from the top (starting from the aldehyde group). The hydroxyl group on this carbon is on the left side.
Change the configuration at C-4: To find the C-4 epimer, invert the configuration of the hydroxyl group at C-4. This means the hydroxyl group on C-4 will now be on the right side instead of the left, while the configurations of all other chiral carbons remain unchanged.
Determine the name of the new sugar: After changing the configuration at C-4, the resulting sugar is D-xylulose. Verify the structure to ensure that only the C-4 configuration has been altered and that the sugar remains an aldopentose.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Epimers
Epimers are a specific type of diastereomer that differ in configuration at only one stereogenic center. In the context of sugars, this means that two sugars can have the same molecular formula and differ only at one carbon atom's stereochemistry. Understanding epimers is crucial for identifying relationships between different sugars, such as d-lyxose and its epimer.
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Identifying Types of Stereoisomers
D-lyxose
D-lyxose is a five-carbon aldose sugar that is part of the pentose family. It has specific stereochemical configurations at each of its chiral centers, which are essential for its biological function and reactivity. Knowing the structure of d-lyxose helps in determining its epimer by analyzing the configuration at the C-4 position.
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Sugar Structure and Configuration
The structure and configuration of sugars are defined by their carbon skeletons and the arrangement of hydroxyl groups around the chiral centers. For d-lyxose, the configuration at C-4 is critical for identifying its epimer. By changing the configuration at this specific carbon, one can derive the C-4 epimer, which is essential for answering the question.
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Related Practice
Textbook Question
Indicate whether each of the following structures is D-glyceraldehyde or L-glyceraldehyde, assuming that the horizontal bonds point toward you and the vertical bonds point away from you (Section 4.7):
a.
b.
c.
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Textbook Question
c. What sugar is the C-4 epimer of L-gulose?
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Textbook Question
What are the systematic names of the following compounds? Indicate the configuration (R or S) of each asymmetric center.
b. D-mannose
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Textbook Question
What are the systematic names of the following compounds? Indicate the configuration (R or S) of each asymmetric center.
a. D-glucose
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Textbook Question
a. Are d-erythrose and l-erythrose enantiomers or diastereomers?
b. Are l-erythrose and l-threose enantiomers or diastereomers?