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

12. Alcohols, Ethers, Epoxides and Thiols

Leaving Group Conversions Summary

Organic Chemistry

12. Alcohols, Ethers, Epoxides and Thiols

Leaving Group Conversions Summary

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1:12 minutes

Problem 9a,b

Textbook Question

What stereoisomers do the following reactions form?
a.
b.

Verified step by step guidance

Analyze the first reaction: The starting material is a secondary alcohol with a stereocenter. The reagent HBr under heat will likely proceed via an SN1 mechanism. This involves the formation of a carbocation intermediate, which can lead to racemization at the stereocenter due to the planar nature of the carbocation. The final product will be a brominated compound, and both R and S stereoisomers may form.

Explain the SN1 mechanism for the first reaction: The hydroxyl group (-OH) is protonated by HBr, forming water as a leaving group. The departure of water generates a carbocation intermediate. Since the carbocation is planar, nucleophilic attack by Br⁻ can occur from either side, leading to a mixture of stereoisomers.

Analyze the second reaction: The starting material is the same secondary alcohol with a stereocenter. The reagent SOCl₂ in the presence of pyridine typically proceeds via an SN2 mechanism. In an SN2 reaction, the nucleophile attacks the carbon from the opposite side of the leaving group, resulting in inversion of configuration at the stereocenter.

Explain the SN2 mechanism for the second reaction: Pyridine helps to deprotonate the alcohol, allowing SOCl₂ to convert the hydroxyl group into a good leaving group (chlorosulfite intermediate). The chloride ion (Cl⁻) then performs a backside attack, leading to inversion of the stereochemistry at the carbon center.

Summarize the stereoisomers formed: In the first reaction, a racemic mixture of R and S stereoisomers is formed due to the SN1 mechanism. In the second reaction, only one stereoisomer is formed with inverted configuration due to the SN2 mechanism.

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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 those 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.

Reaction Mechanisms

Understanding reaction mechanisms is crucial for predicting the products of chemical reactions. A reaction mechanism outlines the step-by-step process by which reactants transform into products, including the formation and breaking of bonds. This knowledge helps in determining the stereochemical outcomes of reactions, particularly in cases involving chiral centers.

Chirality

Chirality is a property of a molecule that makes it non-superimposable on its mirror image, much like left and right hands. Molecules that possess chirality typically have one or more chiral centers, often carbon atoms bonded to four different substituents. The presence of chirality in a reaction can lead to the formation of different stereoisomers, which can have significant implications in fields like pharmaceuticals.

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Related Practice

Textbook Question

Predict the major products (including stereochemistry) when cis-3-methylcyclohexanol reacts with the following reagents.

(d) concentrated HBr

(e) TsCl/pyridine, then NaBr

Textbook Question

Show how you would synthesize the following compounds. As starting materials, you may use any alcohols containing four or fewer carbon atoms, cyclohexanol, and any necessary solvents and inorganic reagents.

(g)

Textbook Question

Predict the major products (including stereochemistry) when cis-3-methylcyclohexanol reacts with the following reagents.

(a) PBr₃

(b) SOCl₂

Textbook Question

Suggest how you would convert trans-4-methylcyclohexanol to

a. trans-1-chloro-4-methylcyclohexane.

b. cis-1-chloro-4-methylcyclohexane.

Textbook Question

What stereoisomers do the following reactions form?

Textbook Question