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

NMR Practice

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

NMR Practice

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Problem 64c

Textbook Question

Draw the ¹H NMR spectrum you would expect to see for each of the molecules in Assessment 15.63.
(c)

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Identify the structure of the molecule in question from Assessment 15.63, part c. Determine the number of unique hydrogen environments in the molecule. Each unique environment will correspond to a different signal in the ¹H NMR spectrum.

Analyze the chemical environment of each set of equivalent hydrogens. Consider factors such as electronegativity of nearby atoms, hybridization of the carbon atoms to which the hydrogens are attached, and any resonance effects that might influence the chemical shift.

Predict the splitting pattern for each signal based on the number of neighboring hydrogens (n+1 rule). For example, if a set of hydrogens has two neighboring hydrogens, the signal will be split into a triplet.

Estimate the chemical shift range for each signal using typical ¹H NMR chemical shift values. For instance, hydrogens on sp³ hybridized carbons typically appear between 0-3 ppm, while those on sp² hybridized carbons appear between 4.5-7 ppm.

Consider the integration of each signal, which corresponds to the relative number of hydrogens contributing to that signal. This will help in determining the relative intensity of each peak in the spectrum.

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Key Concepts

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

¹H NMR Spectroscopy

¹H NMR spectroscopy is a technique used to determine the structure of organic compounds by analyzing the magnetic environment of hydrogen atoms. It provides information about the number of hydrogen atoms, their chemical environment, and how they are connected within a molecule. Peaks in the spectrum correspond to different hydrogen environments, and their chemical shifts, multiplicity, and integration help deduce molecular structure.

Chemical Shift

Chemical shift in NMR spectroscopy refers to the position of a signal in the spectrum, measured in parts per million (ppm). It indicates the electronic environment surrounding a nucleus, influenced by nearby electronegative atoms or functional groups. Understanding chemical shifts is crucial for identifying the types of hydrogen atoms present in a molecule and their relative positions.

Spin-Spin Coupling

Spin-spin coupling, or J-coupling, occurs when magnetic interactions between neighboring hydrogen nuclei split NMR signals into multiplets. This splitting provides information about the number of adjacent hydrogen atoms, helping to elucidate the connectivity and arrangement of atoms within a molecule. The pattern and number of peaks in a multiplet reveal the number of neighboring hydrogens.

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02:54

Sonogashira Coupling Reaction

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Related Practice

Textbook Question

(a) Using the ¹H NMR spectra, identify the reactants and product for this reaction.

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Textbook Question

(b) Provide an arrow-pushing mechanism for the reaction.

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Textbook Question

Without worrying about the relative location of the signals (i.e., the chemical shift) or the splitting patterns, draw a spectrum of the following molecule, being sure to indicate the integration of each peak. Label each signal based on the set of equivalent hydrogens to which it corresponds. [We expand on this question in future assessments.]

Textbook Question

Draw the ¹H NMR spectrum you would expect to see for each of the molecules in Assessment 15.63.

(b)

Textbook Question

Draw the ¹H NMR spectrum you would expect to see for each of the molecules in Assessment 15.63.

(d)

Textbook Question

Draw a spectrum for each of the following molecules, being sure to indicate the multiplicity, integration, and chemical shift of each peak. Label each signal based on the set of equivalent hydrogens to which it corresponds.

(b)

Textbook Question

(c)

Textbook Question

Assign the peaks in the ¹H NMR spectrum for the molecule shown.

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