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

Carbon NMR

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

Carbon NMR

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Problem 50b

Textbook Question

Assign each signal in the ¹³C NMR spectra to the molecule shown.
(b) <IMAGE>

Verified step by step guidance

Begin by examining the molecular structure provided. Identify the different types of carbon environments present in the molecule. Each unique carbon environment will correspond to a distinct signal in the ¹³C NMR spectrum.

Consider the hybridization of each carbon atom. Carbons can be sp³, sp², or sp hybridized, and this affects their chemical shift in the NMR spectrum. Typically, sp³ hybridized carbons appear at lower chemical shifts, while sp² and sp hybridized carbons appear at higher chemical shifts.

Look for symmetry in the molecule. Symmetrical molecules may have equivalent carbon atoms that produce the same signal in the NMR spectrum. Identify any such equivalent carbons.

Consider the electronegativity of atoms or groups attached to each carbon. Electronegative atoms or groups can deshield the carbon, causing its signal to appear at a higher chemical shift. Analyze the proximity of each carbon to electronegative atoms or groups.

Finally, match each carbon environment to the corresponding signal in the ¹³C NMR spectrum based on the chemical shift values. Use known chemical shift ranges for different types of carbon environments to make these assignments.

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Key Concepts

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

¹³C NMR Spectroscopy

¹³C NMR spectroscopy is a technique used to determine the structure of organic compounds by analyzing the magnetic environment of carbon atoms. Each carbon atom in a molecule can produce a distinct signal in the NMR spectrum, depending on its electronic environment. This method is crucial for identifying the number and types of carbon environments in a compound.

Chemical Shift

Chemical shift in NMR spectroscopy refers to the resonant frequency of a nucleus relative to a standard in a magnetic field. It provides information about the electronic environment surrounding a nucleus. In ¹³C NMR, chemical shifts are influenced by factors such as electronegativity of nearby atoms and hybridization, helping to distinguish between different carbon environments in a molecule.

Signal Assignment

Signal assignment in NMR involves correlating each peak in the spectrum to a specific atom or group of atoms in the molecule. This process requires understanding the chemical shift values and the molecular structure. By analyzing the number of signals and their chemical shifts, one can deduce which carbon atoms correspond to which signals, aiding in the structural elucidation of the compound.

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