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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3:15 minutes

Problem 47b(2)

Textbook Question

How many signals are produced by each of the following compounds in its
b. ¹³C NMR spectrum?
2.

Verified step by step guidance

Analyze the structure of the compound. The molecule consists of a benzene ring with a methyl group attached to one position, a ketone group attached to another position, and an ethoxy group attached to the ketone.

Determine the symmetry of the benzene ring. The methyl group creates asymmetry, meaning the carbons in the benzene ring are not equivalent. Each carbon in the benzene ring will produce a unique signal in the 13C NMR spectrum.

Consider the methyl group attached to the benzene ring. The carbon in the methyl group is unique and will produce its own signal.

Examine the ketone group. The carbonyl carbon (C=O) is distinct and will produce a separate signal in the 13C NMR spectrum.

Analyze the ethoxy group. The ethoxy group contains two unique carbons: the carbon directly attached to the oxygen and the terminal carbon in the ethyl chain. Each of these carbons will produce separate signals in the 13C NMR spectrum.

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Key Concepts

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

Nuclear Magnetic Resonance (NMR) Spectroscopy

NMR spectroscopy is a powerful analytical technique used to determine the structure of organic compounds. It relies on the magnetic properties of certain nuclei, such as carbon-13 (13C), to provide information about the environment surrounding these nuclei. In 13C NMR, different carbon environments produce distinct signals, allowing chemists to infer the number and types of carbon atoms in a molecule.

Chemical Shifts

Chemical shifts in NMR spectroscopy refer to the variation in resonance frequency of a nucleus due to its electronic environment. In 13C NMR, the chemical shift is influenced by factors such as electronegativity of nearby atoms and hybridization. This shift helps in distinguishing between different types of carbon atoms, such as those in aliphatic, aromatic, or functional groups, which is crucial for interpreting the spectrum.

Signal Multiplicity and Integration

In NMR spectroscopy, the multiplicity of a signal indicates the number of neighboring hydrogen atoms (or other nuclei) that influence the resonance of a particular carbon atom. While 13C NMR typically shows singlets for each unique carbon environment, understanding the integration of these signals can provide insights into the number of equivalent carbons present. This concept is essential for accurately determining the number of signals in the spectrum.

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