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

5. Chirality

Constitutional Isomers vs. Stereoisomers

Organic Chemistry

5. Chirality

Constitutional Isomers vs. Stereoisomers

Previous problemNext problem

2:38 minutes

Problem 41a

Textbook Question

Draw the stereoisomers of the following amino acids. Indicate pairs of enantiomers and pairs of diastereomers.
a.

Verified step by step guidance

Step 1: Identify the chiral centers in the given amino acid structure. A chiral center is a carbon atom bonded to four different groups. In this structure, the central carbon atom is bonded to a methyl group (CH3), a hydrogen atom (H), an amino group (NH2), and a carboxylic acid group (COOH), making it a chiral center.

Step 2: Determine the possible stereoisomers. A molecule with one chiral center can have two stereoisomers: one with the R configuration and one with the S configuration. These stereoisomers are enantiomers, which are non-superimposable mirror images of each other.

Step 3: Draw the Fischer projections for the two enantiomers. In a Fischer projection, the horizontal bonds represent groups coming out of the plane, and the vertical bonds represent groups going into the plane. Assign the R and S configurations based on the Cahn-Ingold-Prelog priority rules.

Step 4: Consider the possibility of diastereomers. Diastereomers occur when there are multiple chiral centers in a molecule. Since this amino acid has only one chiral center, there are no diastereomers in this case.

Step 5: Label the pairs of enantiomers clearly in your drawings. Indicate which stereoisomer is R and which is S, and ensure the mirror image relationship is evident in the diagrams.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

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. The two main types of stereoisomers are enantiomers, which are non-superimposable mirror images, and diastereomers, which are not mirror images of each other.

Chirality

Chirality is a property of a molecule that has a non-superimposable mirror image, often due to the presence of a chiral center, typically a carbon atom bonded to four different substituents. Amino acids are often chiral, leading to two enantiomers (D and L forms) that can have different biological activities. Identifying chirality is crucial for understanding the behavior of amino acids in biological systems.

Enantiomers and Diastereomers

Enantiomers are pairs of stereoisomers that are mirror images of each other, such as the D and L forms of amino acids. They exhibit identical physical properties except for their interaction with plane-polarized light and reactions in chiral environments. Diastereomers, on the other hand, are stereoisomers that are not mirror images and can have different physical and chemical properties, making their identification important in organic chemistry.

Watch next

Master Determining when molecules are different. with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

For many centuries, the Chinese have used extracts from a group of herbs known as ephedra to treat asthma. A compound named ephedrine has been isolated from these herbs and found to be a potent dilator of air passages in the lungs.

a. How many stereoisomers does ephedrine have?

b. The stereoisomer shown here is the one that is pharmacologically active. What is the configuration of each of the asymmetric centers?

Textbook Question

How many stereoisomers are possible for each of the following molecules?

(a)

Textbook Question

How many stereoisomers are possible for each of the following molecules?

(c)

Textbook Question

Draw a three-dimensional structure for each compound, and star all asymmetric carbon atoms. Draw the mirror for each structure, and state whether you have drawn a pair of enantiomers or just the same molecule twice. Build molecular models of any of these examples that seem difficult to you

(a)

(b)

Textbook Question

Which of the following pairs of compounds could be separated by recrystallization or distillation?

a. meso-tartaric acid and (±)-tartaric acid (HOOC—CHOH—CHOH—COOH)

Textbook Question

Draw the enantiomer, if any, for each structure.

(e)

(f)

Textbook Question

1-Bromo-2-methylcyclopentane has four pairs of diastereomers. Draw the four pairs.

Textbook Question