Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

28. Carbohydrates

Monosaccharides - Strong Oxidation (Aldaric Acid)

Organic Chemistry

28. Carbohydrates

Monosaccharides - Strong Oxidation (Aldaric Acid)

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4:25 minutes

Problem 14c

Textbook Question

Name another pair of aldohexoses that are oxidized to identical aldaric acids.

Verified step by step guidance

Understand the problem: Aldohexoses are six-carbon sugars with an aldehyde group. When oxidized, both the aldehyde group at C-1 and the primary alcohol group at C-6 are converted into carboxylic acids, forming aldaric acids. The task is to identify a pair of aldohexoses that yield the same aldaric acid upon oxidation.

Recall the concept of stereoisomers: Aldohexoses can have different configurations at their chiral centers (C-2, C-3, C-4, and C-5). Two aldohexoses that differ only in the configuration of their non-terminal chiral centers (C-2, C-3, C-4, or C-5) are called epimers. Epimers at C-2, C-3, or C-4 can sometimes yield the same aldaric acid upon oxidation.

Identify the key property: When oxidized, the stereochemistry at the non-terminal chiral centers (C-2, C-3, C-4, and C-5) determines whether two aldohexoses produce the same aldaric acid. If the stereochemistry of the two sugars is symmetric about the central carbon (C-3), they will yield the same aldaric acid.

Apply the concept to specific aldohexoses: For example, D-mannose and D-gulose are epimers at C-2 and C-3, respectively. Their stereochemistry is symmetric about C-3, so they are oxidized to the same aldaric acid.

Verify the result: Draw the Fischer projections of the two aldohexoses and their corresponding aldaric acid. Confirm that the aldaric acid has identical stereochemistry regardless of which aldohexose is oxidized.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Aldohexoses

Aldohexoses are six-carbon sugars that contain an aldehyde group. They are a subclass of monosaccharides and include common sugars like glucose and galactose. The structure of aldohexoses allows them to undergo various chemical reactions, including oxidation, which is crucial for understanding their reactivity and transformations.

Oxidation of Sugars

Oxidation in organic chemistry refers to the process where a molecule loses electrons, often involving the conversion of an aldehyde group to a carboxylic acid. In the context of aldohexoses, this reaction can lead to the formation of aldaric acids, which are dicarboxylic acids derived from the oxidation of both the aldehyde and the primary alcohol groups present in the sugar.

Aldaric Acids

Aldaric acids are dicarboxylic acids formed from the oxidation of both the aldehyde and the terminal alcohol functional groups of aldohexoses. They have the general formula HOOC-(CHOH)n-COOH, where n is the number of carbon atoms between the two carboxylic acid groups. Identifying pairs of aldohexoses that yield the same aldaric acid upon oxidation is essential for understanding their structural similarities and reactivity.

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Related Practice

Textbook Question

Identify the sugar in each description.

b. A sugar that is not D-altrose forms D-altraric acid when it is oxidized with nitric acid.

Textbook Question

Which of the D-aldopentoses will give optically active aldaric acids on oxidation with HNO₃?

Textbook Question

Which of the D-aldotetroses will give optically active aldaric acids on oxidation with HNO₃?

Textbook Question

How many aldaric acids are obtained from the 16 aldohexoses?

Textbook Question

Two sugars, A and B, are known to be glucose and galactose, but it is not certain which one is which. On treatment with nitric acid, A gives an optically inactive aldaric acid, while B gives an optically active aldaric acid. Which sugar is glucose, and which is galactose?

Textbook Question

Draw and name the products of nitric acid oxidation of

(a) D-mannose

(b) D-galactose

Textbook Question

a. Name an aldohexose other than D-glucose that is oxidized to D-glucaric acid by nitric acid.

b. What is another name for D-glucaric acid?

Textbook Question

Identify the sugar in each description.

b. A sugar that is not D-altrose forms D-altraric acid when it is oxidized with nitric acid.

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