Textbook Question
How many stereoisomers are possible for b. an aldoheptose?
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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 7
What sugar is the C-3 epimer of D-fructose?
Verified step by step guidance1
Understand the concept of epimers: Epimers are stereoisomers that differ in configuration at only one specific carbon atom, while the rest of the molecule remains identical. In this case, we are looking for the C-3 epimer of D-fructose.
Recall the structure of D-fructose: D-fructose is a ketohexose, meaning it has six carbons and a ketone functional group at the C-2 position. Its Fischer projection shows the hydroxyl (-OH) groups on specific carbons (C-3, C-4, and C-5) in a particular arrangement.
Identify the C-3 position: In the Fischer projection of D-fructose, the C-3 carbon is the third carbon from the top, and its hydroxyl group is on the left side of the projection.
Generate the C-3 epimer: To create the C-3 epimer, invert the configuration of the hydroxyl group at the C-3 position. If the hydroxyl group is on the left in D-fructose, place it on the right for the epimer, while keeping the rest of the molecule unchanged.
Name the resulting sugar: After modifying the C-3 position, determine the name of the new sugar by comparing its structure to known ketohexoses. This will give you the name of the C-3 epimer of D-fructose.
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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-fructose and its epimers.
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Identifying Types of Stereoisomers
D-Fructose Structure
D-fructose is a ketohexose sugar, meaning it contains six carbon atoms and a ketone functional group. Its structure includes a carbonyl group at C-2 and hydroxyl groups at the other carbons. Recognizing the structure of d-fructose is essential for determining its epimers, particularly by identifying the stereochemistry at C-3.
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Sugar Nomenclature
Sugar nomenclature involves the systematic naming of carbohydrates based on their structure and stereochemistry. The prefixes 'D-' and 'L-' indicate the configuration of the sugar relative to glyceraldehyde, while terms like 'epimer' specify the type of stereochemical difference. Familiarity with this nomenclature is important for accurately identifying and discussing sugars and their relationships.
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Related Practice
Textbook Question
How many stereoisomers are possible for a. a ketoheptose?
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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
When D-tagatose is added to a basic aqueous solution, an equilibrium mixture of monosaccharides is obtained, two of which are aldohexoses and two of which are ketohexoses. Identify the aldohexoses and ketohexoses.
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Textbook Question
d. What sugar is the C-4 epimer of D-lyxose?
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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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