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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5:11 minutes

Problem 69c

Textbook Question

Sketch the following spectra that would be obtained for 2-chloroethanol:
c. The ¹³C NMR spectrum.

Verified step by step guidance

Identify the structure of 2-chloroethanol (ClCH2CH2OH). It contains two carbon atoms: one bonded to a chlorine atom and the other bonded to a hydroxyl group. These two carbons are chemically non-equivalent, meaning they will produce distinct signals in the 13C NMR spectrum.

Determine the chemical environment of each carbon atom. The carbon bonded to the chlorine atom (ClCH2-) is deshielded due to the electronegativity of chlorine, resulting in a downfield shift. The carbon bonded to the hydroxyl group (-CH2OH) is also deshielded, but to a lesser extent than the chlorine-bonded carbon.

Predict the approximate chemical shift range for each carbon. The carbon bonded to chlorine typically appears in the range of 40-80 ppm, while the carbon bonded to the hydroxyl group typically appears in the range of 50-70 ppm. These ranges are approximate and depend on the solvent and other experimental conditions.

Consider the splitting pattern. In 13C NMR, splitting due to coupling with directly bonded hydrogens (1H) is often not observed because broadband decoupling is typically used. Therefore, each carbon will appear as a single peak.

Sketch the spectrum. Represent the two distinct peaks on the x-axis (chemical shift in ppm) with their approximate positions based on the predicted ranges. Label the peak at the lower ppm value as the carbon bonded to the hydroxyl group (-CH2OH) and the peak at the higher ppm value as the carbon bonded to chlorine (ClCH2-).

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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 exploits the magnetic properties of certain nuclei, such as carbon-13 (13C), to provide information about the number and environment of carbon atoms in a molecule. The resulting spectrum displays peaks corresponding to different carbon environments, allowing chemists to infer structural details.

Chemical Shifts in 13C NMR

Chemical shifts in 13C NMR refer to the variation in resonance frequency of carbon nuclei due to their electronic environment. Each unique carbon atom in a molecule will resonate at a different frequency, which is measured in parts per million (ppm). The position of these peaks on the spectrum provides insight into the types of functional groups and the overall structure of the compound.

Integration and Peak Multiplicity

In 13C NMR, integration refers to the area under the peaks, which correlates with the number of equivalent carbon atoms contributing to that signal. Peak multiplicity, influenced by neighboring hydrogen atoms, indicates the number of adjacent protons and helps deduce the connectivity of the carbon atoms. Understanding these aspects is crucial for interpreting the spectrum of 2-chloroethanol accurately.

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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

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

b. ¹³C NMR spectroscopy?

Textbook Question

Sketch the following spectra that would be obtained for 2-chloroethanol:

d. The proton-coupled ¹³C NMR spectrum.

Textbook Question

Compound A, with molecular formula C₄H₉Cl, shows two signals in its ¹³C NMR spectrum. Compound B, an isomer of compound A, shows four signals, and in the proton-coupled mode, the signal farthest downfield is a doublet. Identify compounds A and B.

Textbook Question

Describe the proton-coupled ¹³C NMR spectra for compound 5 in Problem 41, indicating the relative positions of the signals.

Textbook Question

Answer the following questions for each compound:

a. How many signals are in its ¹³C NMR spectrum?

b. Which signal is at the lowest frequency?

9. CH₂=CHBr

Textbook Question

Answer the following questions for each compound:

a. How many signals are in its ¹³C NMR spectrum? b. Which signal is at the lowest frequency?

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