1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 19m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 18m
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 Acids3h 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

Epimerization

Organic Chemistry

28. Carbohydrates

Epimerization

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1:04 minutes

Problem 20-5cBruice - 8th Edition

Textbook Question

c. What sugar is the C-4 epimer of l-gulose?

Verified step by step guidance

Understand the concept of epimers: Epimers are sugars that differ in configuration at only one specific carbon atom. In this case, we are looking for the C-4 epimer of L-gulose.

Identify the structure of L-gulose: L-gulose is an aldohexose, which means it has six carbon atoms and an aldehyde group. Draw the Fischer projection of L-gulose to visualize its stereochemistry.

Locate the C-4 carbon in L-gulose: In the Fischer projection, the carbon atoms are numbered from the top (the aldehyde group) to the bottom. Identify the fourth carbon atom (C-4) in the chain.

Change the configuration at C-4: To find the C-4 epimer, invert the stereochemistry at the C-4 carbon atom. If the hydroxyl group (-OH) is on the right in L-gulose, place it on the left, and vice versa.

Determine the name of the new sugar: After changing the configuration at C-4, identify the new sugar structure. Compare it with known sugar structures to find its name.

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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 l-gulose and its epimer.

Sugar Structure

Sugars, or carbohydrates, are organic compounds made up of carbon, hydrogen, and oxygen, typically in a ring or linear form. The structure of a sugar is defined by its carbon backbone and the arrangement of hydroxyl (-OH) groups. Recognizing the structure of l-gulose, which is an aldohexose, is essential for determining its epimer at C-4.

D- and L- Configuration

The D- and L- notation refers to the configuration of sugars based on the orientation of the hydroxyl group on the chiral carbon farthest from the carbonyl group. In the case of l-gulose, it is important to understand how the D- and L- forms relate to each other, as the C-4 epimer will have a different configuration at that specific carbon, leading to the identification of the corresponding sugar.