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

Alcohol Nomenclature

Organic Chemistry

12. Alcohols, Ethers, Epoxides and Thiols

Alcohol Nomenclature

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7:14 minutes

Problem 33a,b

Textbook Question

Predict which member of each pair has the higher boiling point, and explain the reasons for your predictions.
a. hexan-1-ol or 3,3-dimethylbutan-1-ol
b. hexan-2-one or hexan-2-ol

Verified step by step guidance

Step 1: Understand the factors affecting boiling points. Boiling points are influenced by intermolecular forces such as hydrogen bonding, dipole-dipole interactions, and London dispersion forces. Molecules with stronger intermolecular forces generally have higher boiling points.

Step 2: Analyze (a) hexan-1-ol vs. 3,3-dimethylbutan-1-ol. Both are alcohols, meaning they can form hydrogen bonds due to the presence of the hydroxyl (-OH) group. However, hexan-1-ol has a straight-chain structure, which allows for stronger London dispersion forces compared to the branched structure of 3,3-dimethylbutan-1-ol. Branching reduces the surface area available for intermolecular interactions, lowering the boiling point.

Step 3: Analyze (b) hexan-2-one vs. hexan-2-ol. Hexan-2-one is a ketone, which can only exhibit dipole-dipole interactions due to the polar carbonyl group. Hexan-2-ol, on the other hand, is an alcohol and can form hydrogen bonds in addition to dipole-dipole interactions. Hydrogen bonding is significantly stronger than dipole-dipole interactions, so hexan-2-ol is expected to have a higher boiling point.

Step 4: Compare molecular weights and structures. Both pairs of compounds have similar molecular weights, so the differences in boiling points are primarily due to the types and strengths of intermolecular forces rather than size.

Step 5: Summarize the predictions. For (a), hexan-1-ol is predicted to have a higher boiling point due to its straight-chain structure and stronger London dispersion forces. For (b), hexan-2-ol is predicted to have a higher boiling point due to the presence of hydrogen bonding, which is stronger than the dipole-dipole interactions in hexan-2-one.

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Key Concepts

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

Hydrogen Bonding

Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen or nitrogen. In alcohols, the presence of an -OH group allows for hydrogen bonding between molecules, significantly increasing their boiling points compared to hydrocarbons of similar molecular weight, which lack such interactions.

Molecular Structure and Steric Hindrance

Molecular structure refers to the arrangement of atoms within a molecule, which can influence physical properties like boiling point. Steric hindrance occurs when bulky groups around a functional group impede interactions, such as hydrogen bonding. In the case of 3,3-dimethylbutan-1-ol, the presence of two methyl groups near the -OH group reduces the ability to form hydrogen bonds compared to hexan-1-ol, leading to a lower boiling point.

Functional Groups and Polarity

Functional groups are specific groups of atoms within molecules that determine their chemical properties. The polarity of a molecule, influenced by its functional groups, affects its boiling point; polar molecules, like alcohols, generally have higher boiling points due to stronger intermolecular forces. In comparing hexan-2-one and hexan-2-ol, the alcohol's -OH group introduces polarity and hydrogen bonding, resulting in a higher boiling point than the ketone.

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