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

Naming Alkenes

Organic Chemistry

4. Alkanes and Cycloalkanes

Naming Alkenes

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5:33 minutes

Problem 12

Textbook Question

Draw the molecular orbital picture of but-2-yne.

Verified step by step guidance

Start by identifying the molecular structure of but-2-yne. It is a four-carbon alkyne with a triple bond between the second and third carbon atoms. The molecular formula is C4H6.

Determine the hybridization of each carbon atom. The two carbons involved in the triple bond (C2 and C3) are sp-hybridized, while the terminal carbons (C1 and C4) are sp3-hybridized.

Construct the molecular orbitals for the triple bond. The sp-hybridized carbons (C2 and C3) each have one sp orbital forming a sigma (σ) bond and two unhybridized p orbitals forming two pi (π) bonds. Represent these orbitals in the molecular orbital diagram.

Include the sigma bonds between C1-C2 and C3-C4. These are formed by the overlap of sp3 orbitals from the terminal carbons (C1 and C4) with the sp orbitals of C2 and C3, respectively.

Finally, add the hydrogen atoms. Each hydrogen atom forms a sigma bond with the sp3 orbitals of the terminal carbons (C1 and C4). Ensure the molecular orbital diagram reflects all bonding and antibonding interactions accurately.

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Key Concepts

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

Molecular Orbitals

Molecular orbitals (MOs) are formed by the combination of atomic orbitals when atoms bond together. In but-2-yne, the overlap of atomic orbitals leads to the formation of bonding and antibonding molecular orbitals, which help determine the stability and reactivity of the molecule. Understanding MOs is crucial for visualizing electron distribution and predicting molecular behavior.

Hybridization

Hybridization is the process by which atomic orbitals mix to form new hybrid orbitals that are suitable for the pairing of electrons to form chemical bonds. In but-2-yne, the carbon atoms undergo sp hybridization, resulting in linear geometry around the triple bond. This concept is essential for understanding the bonding and geometry of the molecule.

Triple Bonding

A triple bond consists of one sigma bond and two pi bonds formed between two atoms, resulting in a strong and stable connection. In but-2-yne, the presence of a triple bond between the two central carbon atoms significantly influences the molecule's properties, including its reactivity and physical characteristics. Recognizing the nature of triple bonds is vital for accurately drawing and interpreting the molecular structure.

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Related Practice

Textbook Question

Draw the structure for each of the following:

a. 3,3-dimethylcyclopentene

b. 6-bromo-2,3-dimethyl-2-hexene

Textbook Question

Name the following:

Textbook Question

The following names are all incorrect. Draw the structure represented by the incorrect name (or a consistent structure if the name is ambiguous), and give your drawing the correct name.

e. 2,5-dimethylcyclohexene

Textbook Question

Write structural formulas for the following compounds (includes both old- and new-style names).

(d) cyclohexylacetylene

(e) 5-methyl-3-octyne

(f) trans-3,5-dibromocyclodecyne

Textbook Question

Draw the molecular orbital picture of pent-1-en-3-yne.

Textbook Question

Draw the skeletal structures for the compounds in Problem 42.

d. vinyl bromide

e. 1,2-dimethylcyclopentene