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

15. Analytical Techniques:IR, NMR, Mass Spect

1H NMR:Q-Test

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

1H NMR:Q-Test

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5:39 minutes

Problem 44

Textbook Question

Replace Hₐ and H₆ in acetone with a deuterium. What is the relationship between the two products you obtain? Based on this, would you expect the two hydrogens to give one or two signals in the ¹H NMR spectrum?

Verified step by step guidance

Identify the structure of acetone: Acetone is a simple ketone with the formula (CH₃)₂CO. It consists of a central carbonyl group (C=O) flanked by two methyl groups (CH₃).

Understand the concept of deuterium substitution: Deuterium (D) is an isotope of hydrogen with one neutron. Replacing hydrogen atoms with deuterium in a molecule can affect its NMR properties.

Determine the positions of Hₐ and H₆ in acetone: In acetone, the hydrogens on the methyl groups are equivalent due to the symmetry of the molecule. Therefore, Hₐ and H₆ refer to any of the hydrogens on the methyl groups.

Consider the symmetry and equivalence in acetone: When you replace Hₐ and H₆ with deuterium, the symmetry of the molecule means that the two products are identical. This is because the methyl groups are equivalent and the substitution does not break the symmetry.

Predict the NMR signals: In ¹H NMR, equivalent hydrogens give rise to a single signal. Since the two hydrogens (Hₐ and H₆) are equivalent in acetone, replacing them with deuterium will not change this equivalence. Therefore, you would expect these hydrogens to give one signal in the ¹H NMR spectrum.

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Key Concepts

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

Isotopic Substitution

Isotopic substitution involves replacing an atom in a molecule with another isotope of the same element, such as replacing hydrogen (H) with deuterium (D). This substitution can affect the physical and chemical properties of the molecule, including its behavior in spectroscopic analysis, due to the difference in mass between isotopes.

Chemical Equivalence in NMR

Chemical equivalence in NMR refers to the condition where nuclei in a molecule experience the same electronic environment, resulting in a single signal in the NMR spectrum. In acetone, the two hydrogens (Hₐ and H₆) are chemically equivalent, meaning they are in identical environments and would typically produce one signal in the ¹H NMR spectrum.

NMR Spectroscopy

NMR spectroscopy is a technique used to determine the structure of organic compounds by analyzing the magnetic properties of atomic nuclei. In ¹H NMR, the number of signals corresponds to the number of distinct hydrogen environments in a molecule. Isotopic substitution, such as replacing hydrogen with deuterium, can alter the NMR signals due to changes in the magnetic environment.

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Textbook Question

For the following compounds, which pairs of hydrogens (H_a and H_b) are enantiotopic hydrogens?

Textbook Question

For the following compounds, which pairs of hydrogens (H_a and H_b) are enantiotopic hydrogens?

Textbook Question

If rotation is restricted, as in the case of the molecule shown, the hydrogens labeled a and b are nonequivalent. Why?

Textbook Question

Replace Hₐ, H₆, and H꜀ in methyl benzene with a deuterium. What is the relationship between the three products you obtain? Based on this, how many signals would you expect for these hydrogens in the ¹H NMR spectrum?

Textbook Question

How can 1,2-, 1,3-, and 1,4-dinitrobenzene be distinguished by

a. ¹H NMR spectroscopy?

Open Question

Identify the indicated set of protons as unrelated, homotopic, enantiotopic, or diastereotopic.

Open Question

Identify the indicated set of protons as unrelated, homotopic, enantiotopic, or diastereotopic.

Open Question

Identify the indicated set of protons as unrelated, homotopic, enantiotopic, or diastereotopic.

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