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

4. Alkanes and Cycloalkanes

Alkyl Groups

Organic Chemistry

4. Alkanes and Cycloalkanes

Alkyl Groups

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3:52 minutes

Problem 41a,b

Textbook Question

The following names are all incorrect or incomplete, but they represent real structures. Draw each structure and name it correctly.
a. 2-ethylpentane
b. 3-isopropylhexane

Verified step by step guidance

Step 1: Understand the structure implied by the name '2-ethylpentane'. The name suggests a pentane chain with an ethyl group attached to the second carbon. However, this name is incorrect because adding an ethyl group to a pentane chain at the second position would result in a longer chain, not a pentane.

Step 2: Draw the structure for '2-ethylpentane'. Start with a five-carbon chain (pentane) and attempt to add an ethyl group to the second carbon. You will notice that this creates a seven-carbon chain, which should be named as heptane.

Step 3: Correct the name for '2-ethylpentane'. Since the longest chain is now seven carbons, the correct name should be '3-methylheptane', where the ethyl group is actually a methyl group on the third carbon of the heptane chain.

Step 4: Understand the structure implied by the name '3-isopropylhexane'. The name suggests a hexane chain with an isopropyl group attached to the third carbon. However, this name is incorrect because adding an isopropyl group to a hexane chain at the third position would result in a longer chain, not a hexane.

Step 5: Correct the name for '3-isopropylhexane'. Draw the structure starting with a six-carbon chain (hexane) and attempt to add an isopropyl group to the third carbon. You will notice that this creates a seven-carbon chain, which should be named as '4-methylheptane', where the isopropyl group is actually a methyl group on the fourth carbon of the heptane chain.

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Key Concepts

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

IUPAC Nomenclature

IUPAC nomenclature is a standardized system for naming chemical compounds. It ensures that each compound has a unique name based on its structure, using rules for identifying the longest carbon chain, numbering the chain, and naming substituents. Understanding these rules is crucial for correctly naming organic molecules.

Identifying the Longest Carbon Chain

In organic chemistry, identifying the longest continuous carbon chain is essential for naming compounds. This chain serves as the base name of the molecule, and substituents are named and numbered based on their position relative to this chain. Misidentifying the longest chain can lead to incorrect naming.

Substituent Positioning and Naming

Substituents are groups attached to the main carbon chain, and their correct identification and positioning are vital for accurate nomenclature. The position is indicated by the lowest possible numbers, and common substituents like ethyl, methyl, and isopropyl have specific naming conventions. Properly naming and numbering these groups ensures clarity and correctness in chemical communication.

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