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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7:54 minutes

Problem 67c,d

Textbook Question

c. How many are isolated dienes?
d. How many are cumulated dienes?

Verified step by step guidance

Step 1: Understand the definitions of isolated and cumulated dienes. An isolated diene has two double bonds separated by at least one sp³-hybridized carbon atom, while a cumulated diene has two double bonds directly adjacent to each other, sharing a common carbon atom (also known as an allene structure).

Step 2: Examine the molecular structure of the compound(s) provided in the problem. Identify all the double bonds present in the structure.

Step 3: Determine the spatial arrangement of the double bonds. Check if there are any sp³-hybridized carbons separating the double bonds (indicating isolated dienes) or if the double bonds are directly adjacent (indicating cumulated dienes).

Step 4: Count the number of isolated dienes by identifying all sets of double bonds that are separated by at least one sp³-hybridized carbon atom.

Step 5: Count the number of cumulated dienes by identifying all sets of double bonds that share a common carbon atom. Ensure that you do not double-count any dienes.

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Key Concepts

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

Dienes

Dienes are organic compounds that contain two double bonds. They can be classified into different types based on the arrangement of these double bonds. Understanding the structure of dienes is crucial for identifying them in chemical reactions and determining their reactivity.

Isolated Dienes

Isolated dienes are characterized by having double bonds separated by at least one single bond. This configuration affects their stability and reactivity, making them distinct from other types of dienes. Recognizing isolated dienes is essential for predicting their behavior in organic reactions.

Cumulated Dienes

Cumulated dienes, also known as conjugated dienes, have two double bonds that are adjacent to each other, sharing a common carbon atom. This arrangement leads to unique electronic properties and reactivity patterns. Understanding cumulated dienes is important for grasping concepts related to resonance and stability in organic chemistry.

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Textbook Question

How can you use UV spectroscopy to distinguish between the compounds in each of the following pairs?

Textbook Question

One milligram of a compound of molecular weight 160 is dissolved in 10 mL of ethanol, and the solution is poured into a 1-cm UV cell. The UV spectrum is taken, and there is an absorption at λ_max = 247 nm. The maximum absorbance at 247 nm is 0.50. Calculate the value of e for this absorption.

Textbook Question

The UV spectrum of 1-phenylprop-2-en-1-ol shows an intense absorption at 220 nm and a weaker absorption at 258 nm. When this compound is treated with dilute sulfuric acid, it rearranges to an isomer with an intense absorption at 250 nm and a weaker absorption at 290 nm. Suggest a structure for the isomeric product and propose a mechanism for its formation.

Textbook Question

A 4.0 × 10^-5 M solution of a compound in hexane shows an absorbance of 0.40 at 252 nm in a cell with a 1 cm light path. What is the molar absorptivity of the compound in hexane at 252 nm?

Textbook Question

What would be the difference in the colors of the compounds at pH = 3?

Textbook Question

Phenolphthalein is an acid–base indicator. In solutions of pH < 8.5, it is colorless; in solutions of pH > 8.5, it is deep red-purple. Account for the change in color.

Multiple Choice

Which statement about conjugation is false?

Multiple Choice

Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains?

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