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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4:35 minutes

Problem 19a,b

Textbook Question

Classify each hydrogen atom in the following compounds as primary (1°), secondary (2°), or tertiary (3°).
a. butane
b. isobutane

Verified step by step guidance

Step 1: Understand the classification of hydrogen atoms. In organic chemistry, hydrogen atoms are classified based on the type of carbon atom they are attached to. A primary (1°) hydrogen is attached to a primary carbon, which is bonded to only one other carbon. A secondary (2°) hydrogen is attached to a secondary carbon, bonded to two other carbons. A tertiary (3°) hydrogen is attached to a tertiary carbon, bonded to three other carbons.

Step 2: Analyze the structure of butane. Butane is a straight-chain alkane with the molecular formula C₄H₁₀. Draw the structure of butane: CH₃-CH₂-CH₂-CH₃. Identify the types of carbon atoms present in butane.

Step 3: Classify the hydrogen atoms in butane. In butane, the terminal CH₃ groups are primary carbons, each bonded to one other carbon. Therefore, the hydrogens attached to these CH₃ groups are primary hydrogens. The CH₂ groups are secondary carbons, each bonded to two other carbons, so the hydrogens attached to these CH₂ groups are secondary hydrogens.

Step 4: Analyze the structure of isobutane. Isobutane is a branched alkane with the molecular formula C₄H₁₀. Draw the structure of isobutane: (CH₃)₂CH-CH₃. Identify the types of carbon atoms present in isobutane.

Step 5: Classify the hydrogen atoms in isobutane. In isobutane, the central carbon is a tertiary carbon, bonded to three other carbons, so the hydrogens attached to this carbon are tertiary hydrogens. The terminal CH₃ groups are primary carbons, each bonded to one other carbon, so the hydrogens attached to these CH₃ groups are primary hydrogens.

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Key Concepts

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

Hydrogen Atom Classification

In organic chemistry, hydrogen atoms are classified based on the type of carbon atom they are attached to. A primary (1°) hydrogen is attached to a primary carbon, which is bonded to only one other carbon. A secondary (2°) hydrogen is attached to a secondary carbon, bonded to two other carbons, and a tertiary (3°) hydrogen is attached to a tertiary carbon, bonded to three other carbons.

Structure of Butane

Butane is a straight-chain alkane with the molecular formula C4H10. It consists of four carbon atoms connected in a linear sequence. In butane, the terminal carbon atoms are primary, each bonded to three hydrogens, while the two central carbon atoms are secondary, each bonded to two hydrogens.

Structure of Isobutane

Isobutane, also known as methylpropane, is a branched-chain alkane with the molecular formula C4H10. It has a central carbon atom bonded to three other carbon atoms, making it tertiary, and this carbon is bonded to one hydrogen. The remaining carbon atoms are primary, each bonded to three hydrogens.

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