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

16. Conjugated Systems

Conjugation Chemistry

Organic Chemistry

16. Conjugated Systems

Conjugation Chemistry

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Problem 18b

Textbook Question

For the following terpenes, identify the isoprene units. In cross-linked or ring-containing terpenes, linkages can be formed between more than just C₁ and C₄ of isoprene
(b)

Verified step by step guidance

Step 1: Recall the structure of an isoprene unit. Isoprene is a 5-carbon molecule with the formula \( C_5H_8 \), consisting of a branched chain with two double bonds. The carbons are numbered as follows: \( C_1 \) (methyl group), \( C_2 \), \( C_3 \), \( C_4 \), and \( C_5 \) (terminal double bond).

Step 2: Analyze the structure of farnesol. Farnesol is a sesquiterpene, meaning it is composed of three isoprene units (\( 3 \times C_5H_8 \)). It has a linear structure with a hydroxyl group (-OH) at one end and multiple double bonds along the chain.

Step 3: Break down the farnesol structure into its isoprene units. Look for repeating \( C_5 \) units with the characteristic isoprene pattern: a branched methyl group and a double bond. Identify the boundaries of each \( C_5 \) unit within the molecule.

Step 4: Pay attention to any linkages between the isoprene units. In farnesol, the isoprene units are connected head-to-tail, meaning the \( C_1 \) of one isoprene unit is linked to the \( C_4 \) of the next. Verify these connections in the structure.

Step 5: Highlight the isoprene units in the structure of farnesol. Clearly mark the three \( C_5 \) units and their connections. Note any deviations from the standard \( C_1 \)-\( C_4 \) linkage pattern, such as cross-linking or ring formation, if present.

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Key Concepts

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

Isoprene Unit

The isoprene unit is a fundamental building block of terpenes, consisting of a five-carbon structure with the formula C₅H₈. Terpenes are formed by the polymerization of isoprene units, which can be linked in various ways to create diverse structures. Understanding how these units combine is essential for analyzing the structure and function of terpenes.

Terpene Structure

Terpenes are organic compounds made up of multiple isoprene units and are classified based on the number of isoprene units they contain. For example, monoterpenes have two isoprene units, while sesquiterpenes, like farnesol, consist of three. The arrangement and connectivity of these units can lead to a variety of structural forms, including linear, branched, and cyclic structures.

Cross-Linking in Terpenes

Cross-linking in terpenes refers to the formation of bonds between different isoprene units beyond the typical C₁ and C₄ positions. This can result in complex structures, such as rings or branched chains, which significantly influence the chemical properties and biological functions of the terpenes. Recognizing these linkages is crucial for understanding the diversity and reactivity of terpene compounds.

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Related Practice

Textbook Question

Answer the following questions for the molecular orbitals (MOs) of 1,3,5,7-octatetraene:

e. Which MO is the HOMO and which is the LUMO in the excited state?

Textbook Question

Answer the following questions for the molecular orbitals (MOs) of 1,3,5,7-octatetraene:

d. Which MO is the HOMO and which is the LUMO in the ground state?

Textbook Question

Answer the following questions for the molecular orbitals (MOs) of 1,3,5,7-octatetraene:

c. Which MOs are symmetric, and which are antisymmetric?

Textbook Question

Answer the following questions for the molecular orbitals (MOs) of 1,3,5,7-octatetraene:

a. How many MOs does the compound have?

Textbook Question

For the following terpenes, identify the isoprene units. In cross-linked or ring-containing terpenes, linkages can be formed between more than just C₁ and C₄ of isoprene

(c)

Textbook Question

North American termite soldiers, when encountering enemy insects, contract their mandibular muscles, expelling a mixture of chemicals that essentially trap their enemies in a glue-like substance. This weapon, built into the face of the termite, is called the fontanellar gun. It releases a mixture of pinene (62%), myrcene (27%), and limonene (11%). pinene myrcene limonene 62% 27% 11%

(a) Identify the isoprene units in pinene, myrcene, and limonene.

Textbook Question

Answer the following questions for the molecular orbitals (MOs) of 1,3,5,7-octatetraene:

b. Which are the bonding MOs, and which are the antibonding MOs?

Textbook Question

Answer the following questions for the molecular orbitals (MOs) of 1,3,5,7-octatetraene:

f. What is the relationship between HOMO and LUMO and symmetric and antisymmetric orbitals?

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For the following terpenes, identify the isoprene units. In cross-linked or ring-containing terpenes, linkages can be formed between more than just C1 and C4 of isoprene (b)

Key Concepts

Isoprene Unit

Terpene Structure

Cross-Linking in Terpenes

Watch next

For the following terpenes, identify the isoprene units. In cross-linked or ring-containing terpenes, linkages can be formed between more than just C₁ and C₄ of isoprene
(b)