Textbook Question
The aldaric acid of D-glucose forms two five-membered-ring lactones. Draw their structures.
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 64a,b
Draw each of the following:
a. β-D-talopyranose
b. α-D-idopyranose
Verified step by step guidance1
Step 1: Understand the problem. You are tasked with drawing two specific cyclic forms of sugars: beta-D-talopyranose and alpha-D-idopyranose. These are both pyranose forms, meaning they are six-membered rings containing oxygen.
Step 2: Recall the Fischer projection of D-talo and D-ido sugars. Identify the stereochemistry of the hydroxyl groups (-OH) on the carbon atoms (C2, C3, C4, and C5) based on their D-configuration. This will help you determine the orientation of substituents in the cyclic form.
Step 3: Convert the Fischer projection to a Haworth projection for each sugar. For beta-D-talopyranose, ensure the anomeric hydroxyl group (on C1) is in the equatorial position (beta configuration). For alpha-D-idopyranose, ensure the anomeric hydroxyl group is in the axial position (alpha configuration).
Step 4: Draw the six-membered ring structure (pyranose) for each sugar. Place the oxygen atom in the ring and arrange the substituents (hydroxyl groups and hydrogen atoms) on the carbons according to the stereochemistry determined in Step 2. Ensure the correct orientation of the anomeric hydroxyl group for alpha and beta forms.
Step 5: Double-check your drawings for accuracy. Verify that the stereochemistry matches the D-configuration of the sugars and that the anomeric hydroxyl group is correctly positioned for alpha and beta forms. Label the structures clearly as beta-D-talopyranose and alpha-D-idopyranose.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Pyranose Structure
Pyranoses are six-membered cyclic forms of monosaccharides, typically derived from aldoses. In this structure, the carbonyl group reacts with a hydroxyl group, forming a ring. The configuration of the anomeric carbon (C1) determines whether the sugar is in the alpha or beta form, which is crucial for understanding the stereochemistry of sugars.
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Anomeric Carbon
The anomeric carbon is the carbon atom in a sugar that was originally part of the carbonyl group and becomes a new chiral center upon cyclization. It plays a vital role in determining the sugar's anomeric form: alpha (OH group on the opposite side of the CH2OH group) or beta (OH group on the same side). This distinction affects the sugar's reactivity and interactions in biological systems.
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D and L Configuration
The D and L notation refers to the configuration of the highest-numbered chiral carbon in a sugar molecule. In D-sugars, the hydroxyl group on this carbon is on the right in a Fischer projection, while in L-sugars, it is on the left. This classification is essential for identifying the specific stereoisomer of a sugar, influencing its biological function and properties.
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Related Practice
Textbook Question
How many aldaric acids are obtained from the 16 aldohexoses?
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Textbook Question
The specific rotation of α-D-galactose is 150.7 and that of β-D-galactose is 52.8. When an aqueous mixture that was initially 70% α-D-galactose and 30% β-D-galactose reaches equilibrium, the specific rotation is 80.2. What is the percentage of α-D-galactose and β-D galactose at equilibrium?
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Textbook Question
Draw the mechanism for the elimination step in the Wohl degredation.
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Textbook Question
A hexose is obtained when the residue of a shrub Sterculia setigeria undergoes acid-catalyzed hydrolysis. Identify the hexose from the following experimental information: it undergoes mutarotation; it does not react with Br2; and D-galactonic acid and D-talonic acid are formed when it reacts with Tollens’ reagent.
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Textbook Question
Calculate the percentages of -D-glucose and -D-glucose present at equilibrium from the specific rotations of -D-glucose, -D-glucose, and the equilibrium mixture. Compare your values with those given in Section 20.10. (Hint: The specific rotation of the mixture equals the specific rotation of -D-glucose times the fraction of glucose present in the a-form plus the specific rotation of -D-glucose times the fraction of glucose present in the -form.)
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