Textbook Question
Draw the enantiomer of the following monosaccharides, and in each pair identify the D sugar and the L sugar.
a.
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Ch.20 Carbohydrates
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187
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Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
Chapter 20, Problem 2a
Draw the structures of an aldopentose.
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Understand the term 'ketohexose': A ketohexose is a six-carbon sugar (hexose) that contains a ketone functional group. The ketone group is typically located on the second carbon atom of the chain.
Start by drawing the backbone of the molecule: Create a chain of six carbon atoms, as this is the defining feature of a hexose.
Add the ketone group: Place a double-bonded oxygen (C=O) on the second carbon atom in the chain. This is the ketone functional group.
Add hydroxyl (-OH) groups: Attach hydroxyl groups to the remaining carbon atoms (except the first and last carbons). The arrangement of these groups determines whether the ketohexose is D- or L-configuration. For example, D-fructose is a common ketohexose.
Complete the structure: Add hydrogen atoms to the remaining bonds of the carbon atoms to satisfy the valency of carbon (four bonds per carbon atom). Ensure the structure is consistent with the molecular formula C6H12O6.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Ketohexose
A ketohexose is a type of sugar that contains six carbon atoms and a ketone functional group. The general formula for ketohexoses is C6H12O6, and they are classified as monosaccharides. Common examples include fructose, which is found in many fruits. Understanding the structure of ketohexoses is essential for studying carbohydrate chemistry and metabolism.
Structural Representation
Structural representation refers to the way in which the molecular structure of a compound is depicted, often using line-angle formulas or Fischer projections. For ketohexoses, it is important to accurately represent the arrangement of carbon atoms, functional groups, and stereochemistry. This visual representation aids in understanding the compound's properties and reactivity.
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Stereochemistry
Stereochemistry is the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the case of ketohexoses, the presence of chiral centers leads to different stereoisomers, which can have distinct biological activities. Recognizing the stereochemical configurations is crucial for comprehending the functionality of sugars in biological systems.
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