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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3:57 minutes

Problem 78b(4)

Textbook Question

How many signals are produced by each of the following compounds in its
b. ¹³C NMR spectrum?
4.

Verified step by step guidance

Step 1: Analyze the structure of the compound provided. The compound is an ether with a cyclic structure and an alkyl chain attached. Identify all unique carbon environments in the molecule.

Step 2: Recall that in 13C NMR spectroscopy, each unique carbon environment produces a distinct signal. Carbons in identical environments (symmetry) will produce the same signal.

Step 3: Examine the cyclic portion of the molecule. The ring contains carbons that are not equivalent due to the presence of the oxygen atom and the alkyl substituent. Count the unique carbon environments in the ring.

Step 4: Examine the alkyl chain attached to the ring. The chain contains carbons that are in different environments due to their positions relative to the ring and the oxygen atom. Count the unique carbon environments in the chain.

Step 5: Sum the number of unique carbon environments identified in the ring and the alkyl chain. This total represents the number of signals that will be observed in the 13C NMR spectrum for this compound.

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Key Concepts

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

Carbon Environment

In 13C NMR spectroscopy, each unique carbon environment in a molecule produces a distinct signal. This means that carbons in different chemical environments, such as those bonded to different functional groups or in different hybridization states, will resonate at different frequencies, leading to separate peaks in the spectrum.

Symmetry and Equivalent Carbons

Molecules with symmetrical structures can have equivalent carbons that do not produce separate signals in the NMR spectrum. Identifying symmetry in a compound helps in determining how many unique signals will appear, as equivalent carbons contribute to a single peak rather than multiple peaks.

Integration and Peak Area

In 13C NMR, the area under each peak corresponds to the number of carbons contributing to that signal. While integration is more commonly discussed in 1H NMR, understanding that the intensity of a signal can indicate the number of equivalent carbons is crucial for interpreting the spectrum and confirming the number of signals.

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Related Practice

Textbook Question

An inexperienced graduate student was making some 4-hydroxybutanoic acid. He obtained an excellent yield of a different compound, whose ¹³C NMR spectrum is shown here.

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(a) Propose a structure for this product.

(b) Assign the peaks in the ¹³C NMR spectrum to the carbon atoms in the structure.

Textbook Question

A bottle of allyl bromide was found to contain a large amount of an impurity. A careful distillation separated the impurity, which has the molecular formula C₃H₆O. The following ¹³C NMR spectrum of the impurity was obtained:

<IMAGE>

(a) Propose a structure for this impurity.

(b) Assign the peaks in the ¹³C NMR spectrum to the carbon atoms in the structure.

Textbook Question

How many signals are produced by each of the following compounds in its

b. ¹³C NMR spectrum?

Textbook Question

How many signals are produced by each of the following compounds in its

b. ¹³C NMR spectrum?

Textbook Question

Would it be better to use ¹H NMR or ¹³C NMR spectroscopy to distinguish 1-butene, cis-2-butene, and 2-methylpropene? Explain your answer.

Textbook Question