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

Monosaccharide

Organic Chemistry

28. Carbohydrates

Monosaccharide

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2:53 minutes

Problem 8b

Textbook Question

How many stereoisomers are possible for b. an aldoheptose?

Verified step by step guidance

Determine the general formula for the number of stereoisomers of a molecule with chiral centers. The formula is 2^n, where n is the number of chiral centers in the molecule.

Understand the structure of an aldoheptose. An aldoheptose is a seven-carbon sugar (heptose) with an aldehyde functional group (-CHO) at one end.

Identify the number of chiral centers in an aldoheptose. Since the aldehyde group is at one end, the remaining six carbons form the backbone. The first carbon (aldehyde carbon) is not chiral, and the last carbon (primary alcohol group) is also not chiral. The middle five carbons are attached to four different groups, making them chiral centers.

Substitute the number of chiral centers (n = 5) into the formula for stereoisomers: 2^n. This will give the total number of stereoisomers possible for an aldoheptose.

Conclude that the total number of stereoisomers is determined by the formula 2^5, which represents all possible configurations of the five chiral centers.

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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.

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. In sugars, chiral centers are typically carbon atoms that have four different substituents. The number of chiral centers in a molecule directly influences the number of possible stereoisomers, as each chiral center can exist in two configurations (R or S).

Counting 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 an aldoheptose, which has four chiral centers, the calculation would yield 2^4 = 16 possible stereoisomers. This formula highlights the exponential increase in stereoisomer count with the addition of more chiral centers.

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