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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Problem 61

Textbook Question

Draw a skeletal structure for an alkane that has
a. six carbons, all secondary.
b. eight carbons and only primary hydrogens.
c. seven carbons with two isopropyl groups.

Verified step by step guidance

Identify the general formula for alkanes, which is C_nH_{2n+2}, and understand that alkanes are saturated hydrocarbons with only single bonds.

For part (a), recognize that a secondary carbon is bonded to two other carbons. To have six carbons all secondary, consider a cyclic structure like cyclohexane, where each carbon is bonded to two other carbons.

For part (b), understand that primary hydrogens are attached to primary carbons, which are bonded to only one other carbon. To have eight carbons with only primary hydrogens, consider a linear structure like n-octane, where the terminal carbons are primary.

For part (c), recall that an isopropyl group is a branched alkyl group with the structure (CH_3)_2CH-. To have seven carbons with two isopropyl groups, consider a structure like 2,3-dimethylpentane, where the main chain is five carbons long and two isopropyl groups are attached.

Draw the skeletal structures based on the descriptions: (a) cyclohexane for six secondary carbons, (b) n-octane for eight carbons with primary hydrogens, and (c) 2,3-dimethylpentane for seven carbons with two isopropyl groups.

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Key Concepts

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

Alkane Structure

Alkanes are saturated hydrocarbons consisting only of carbon (C) and hydrogen (H) atoms, connected by single bonds. The general formula for alkanes is CnH2n+2, where 'n' is the number of carbon atoms. Understanding the skeletal structure of alkanes is crucial, as it visually represents the arrangement of carbon atoms and their associated hydrogen atoms, which is essential for identifying the type of alkane being described.

Secondary and Primary Carbons

In organic chemistry, carbon atoms can be classified based on the number of other carbon atoms they are bonded to. A secondary carbon is bonded to two other carbons, while a primary carbon is bonded to only one. This classification is important for constructing the skeletal structures requested in the question, as it determines the connectivity and branching of the carbon chain in the alkane.

Isopropyl Groups

An isopropyl group is a branched alkyl group derived from propane, consisting of three carbon atoms with the structure -C(CH3)2. When constructing skeletal structures, recognizing how to represent isopropyl groups is essential, especially when multiple groups are present, as in the case of the seven-carbon alkane with two isopropyl groups. This understanding aids in accurately depicting the molecular structure and ensuring correct connectivity.

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