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 8a
How many stereoisomers are possible for a. a ketoheptose?
Verified step by step guidance1
Understand the structure of a ketoheptose: A ketoheptose is a seven-carbon sugar (heptose) with a ketone functional group. The ketone group is typically located at the second carbon (C-2), making it a 2-ketoheptose.
Determine the number of chiral centers: In a ketoheptose, the ketone group at C-2 is not a chiral center. The remaining five carbons (C-3 to C-7) each have a hydroxyl (-OH) group and a hydrogen (-H) attached, making them potential chiral centers. Therefore, there are 5 chiral centers in a ketoheptose.
Apply the formula for the number of stereoisomers: The number of stereoisomers for a molecule with 'n' chiral centers is given by the formula \( 2^n \). For a ketoheptose with 5 chiral centers, substitute \( n = 5 \) into the formula.
Calculate \( 2^5 \): This step involves determining the total number of stereoisomers by evaluating \( 2^5 \), which represents the possible combinations of configurations (R or S) at each chiral center.
Conclude the total number of stereoisomers: The result from the previous step gives the total number of stereoisomers possible for a ketoheptose, including both enantiomers and diastereomers.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Stereoisomerism
Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. This can lead to different physical and chemical properties. In carbohydrates, stereoisomers arise due to the presence of chiral centers, which are carbon atoms bonded to four different groups.
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Chirality and Chiral Centers
Chirality is a property of a molecule that makes it non-superimposable on its mirror image, much like left and right hands. A chiral center, typically a carbon atom, is bonded to four distinct substituents, leading to two possible configurations (enantiomers). The number of chiral centers in a molecule directly influences the number of stereoisomers it can have.
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Calculating Stereoisomers
The total number of stereoisomers for a compound can be calculated using the formula 2^n, where n is the number of chiral centers. For a ketoheptose, which has multiple chiral centers, this formula helps determine the maximum number of stereoisomers possible. Additionally, the presence of any symmetry in the molecule can reduce the total count of unique stereoisomers.
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Related Practice
Textbook Question
How many stereoisomers are possible for b. an aldoheptose?
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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 monosaccharide is reduced to two alditols, one of which is the alditol obtained from the reduction of
1. D-talose?
2. D-allose?
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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
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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