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

7. Substitution Reactions

Substitution Comparison

Organic Chemistry

7. Substitution Reactions

Substitution Comparison

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7:22 minutes

Problem 11a

Textbook Question

What stereoisomers do the following reactions form?
a.

Verified step by step guidance

Step 1: Analyze the starting material. The given compound is a cyclopentanol with a hydroxyl group (-OH) attached to a stereogenic center. The wedge and dash notation indicates the stereochemistry of the substituents.

Step 2: Examine the first reaction step. Phosphorus tribromide (PBr₃) in pyridine is used to convert the alcohol (-OH) group into a bromide (-Br) group. This reaction proceeds via an SN2 mechanism, which inverts the stereochemistry at the carbon center.

Step 3: Consider the second reaction step. Ethoxide ion (C₂H₅O⁻) acts as a nucleophile in an SN2 reaction with the bromide intermediate. This step also inverts the stereochemistry at the carbon center, resulting in a net retention of the original stereochemistry.

Step 4: Combine the stereochemical effects of both steps. Since both steps involve inversion of stereochemistry, the final product retains the original stereochemistry of the starting material.

Step 5: Conclude the stereoisomer formed. The final product is an ethoxy-substituted cyclopentane with the same stereochemistry as the starting material (wedge or dash orientation preserved).

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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 organic chemistry, stereoisomers include enantiomers and diastereomers, which are crucial for understanding the behavior of chiral molecules in reactions.

Reactions of Alcohols

Alcohols can undergo various reactions, including substitution and elimination. In this case, the reaction of an alcohol with phosphorus tribromide (PBr3) converts the alcohol into a bromide, which can then participate in further reactions. Understanding the mechanism of these reactions is essential for predicting the stereochemical outcomes.

Nucleophilic Substitution Mechanisms

Nucleophilic substitution mechanisms, such as SN1 and SN2, describe how nucleophiles replace leaving groups in organic molecules. The choice of mechanism affects the stereochemistry of the product. For example, SN2 reactions lead to inversion of configuration, while SN1 reactions can result in racemization, making it important to analyze the reaction conditions to determine the stereoisomers formed.

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