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 - Sulfonyl Chlorides

Organic Chemistry

12. Alcohols, Ethers, Epoxides and Thiols

Leaving Group Conversions - Sulfonyl Chlorides

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4:50 minutes

Problem 10a,b

Textbook Question

Show how you would convert propan-1-ol to the following compounds using tosylate intermediates. You may use whatever additional reagents are needed.
a. 1-bromopropane
b. propan-1-amine, CH₃CH₂CH₂NH₂

Verified step by step guidance

Step 1: Begin by converting propan-1-ol (CH3CH2CH2OH) into its tosylate intermediate. This is achieved by reacting propan-1-ol with p-toluenesulfonyl chloride (TsCl) in the presence of a base such as pyridine. The hydroxyl group (-OH) is replaced with a tosyl group (-OTs), forming propyl tosylate (CH3CH2CH2OTs).

Step 2: For part (a), to convert propyl tosylate into 1-bromopropane (CH3CH2CH2Br), perform a nucleophilic substitution reaction. React propyl tosylate with sodium bromide (NaBr) in a polar aprotic solvent like acetone. The tosyl group (-OTs) is replaced by a bromide ion (Br⁻) via an SN2 mechanism.

Step 3: For part (b), to convert propyl tosylate into propan-1-amine (CH3CH2CH2NH2), perform another nucleophilic substitution reaction. React propyl tosylate with excess ammonia (NH3) in a suitable solvent. The tosyl group (-OTs) is replaced by an amine group (-NH2) via an SN2 mechanism.

Step 4: Ensure proper reaction conditions for both conversions. For the SN2 reactions, use polar aprotic solvents to favor the substitution mechanism and avoid side reactions. Maintain appropriate temperatures to optimize reaction rates.

Step 5: After the reactions, purify the products (1-bromopropane and propan-1-amine) using techniques such as distillation or recrystallization, depending on the physical properties of the compounds. Confirm the identity of the products using spectroscopic methods like NMR or IR.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Tosylate Formation

Tosylates are formed by reacting alcohols with tosyl chloride (TsCl) in the presence of a base. This reaction converts the alcohol into a better leaving group, the tosylate, which can facilitate subsequent nucleophilic substitution reactions. The tosylate retains the configuration of the original alcohol, making it a useful intermediate for further transformations.

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions involve the replacement of a leaving group in a molecule with a nucleophile. In the case of converting tosylates, the nucleophile attacks the carbon atom bonded to the tosylate, leading to the formation of a new compound. This mechanism can follow either an SN1 or SN2 pathway, depending on the structure of the substrate and the nucleophile used.

Reagents for Halogenation and Amination

To convert a tosylate to a bromo compound, reagents like sodium bromide (NaBr) in a polar aprotic solvent can be used to facilitate the substitution. For amination, a strong nucleophile such as ammonia (NH3) or an amine can be employed to replace the tosylate with an amine group. Understanding the choice of reagents is crucial for achieving the desired product efficiently.

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