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

Sigmatropic Rearrangement

Organic Chemistry

16. Conjugated Systems

Sigmatropic Rearrangement

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4:08 minutes

Problem 14

Textbook Question

Why was a deuterated compound used in the last reaction on the preceding page?

Verified step by step guidance

The reaction shown involves a thermal rearrangement of a cyclic compound. The use of a deuterated compound (CD2) is significant because deuterium (D) is an isotope of hydrogen and can be tracked during the reaction due to its distinct mass and spectroscopic properties.

Deuterium is used to study reaction mechanisms. In this case, it helps to determine whether the hydrogen atoms are retained in their original positions or if they migrate during the rearrangement process.

The arrows in the starting material indicate the movement of electrons during the reaction. This suggests a pericyclic reaction mechanism, likely a [1,5]-sigmatropic shift, where the hydrogen or deuterium migrates across the molecule.

By using deuterium, researchers can confirm the migration pathway and ensure that the observed product matches the expected mechanism. The presence of CD2H in the product indicates that one deuterium atom has migrated while the other remains in its original position.

This experimental design provides evidence for the reaction mechanism and validates theoretical predictions about the behavior of hydrogen and deuterium in pericyclic reactions.

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Key Concepts

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

Deuterated Compounds

Deuterated compounds are molecules in which one or more hydrogen atoms are replaced with deuterium, a stable isotope of hydrogen. This substitution can affect the physical and chemical properties of the compound, such as its reactivity and stability. In reactions, deuterated compounds can serve as tracers to study reaction mechanisms or to determine the position of hydrogen atoms in the product.

Sigmatropic Rearrangement

Sigmatropic rearrangements are a class of pericyclic reactions where a sigma bond and a pi bond undergo a concerted rearrangement. These reactions often involve the migration of a substituent across a conjugated system, leading to the formation of new bonds. The use of deuterated compounds in these reactions can help elucidate the mechanism by tracking the movement of deuterium during the rearrangement.

Reaction Mechanism Analysis

Analyzing reaction mechanisms involves understanding the step-by-step process by which reactants transform into products. This includes identifying intermediates, transition states, and the role of catalysts or solvents. In the context of using deuterated compounds, mechanistic studies can reveal how the presence of deuterium influences the reaction pathway and the stability of intermediates, providing insights into the fundamental principles of organic chemistry.

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