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1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 19m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 18m
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 Acids3h 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

H NMR Table

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

H NMR Table

4:40 minutes

Problem 13bWade - 9th Edition

Textbook Question

The NMR spectrum of toluene (methylbenzene) was shown in Figure 13-11. (a) How many different kinds of protons are there in toluene? (b) Explain why the aromatic region around d7.2 is broad, with more than one sharp absorption.

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Identify the different types of protons in toluene: the methyl group protons (CH₃) and the aromatic ring protons.

Count the number of distinct proton environments: the methyl group protons are in one environment, and the aromatic protons are in another.

Recognize that the aromatic protons are not all equivalent due to the substitution pattern, leading to multiple signals in the aromatic region.

Explain that the broadness around δ 7.2 ppm is due to the overlap of signals from the different aromatic protons, which are not equivalent.

Note that the methyl protons appear as a singlet due to their equivalent environment and lack of neighboring protons to cause splitting.

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Related Practice

Textbook Question

Predict the approximate chemical shifts of the protons in the following compounds. (c) CH3-O-CH2CH2CH2Cl (d) CH3CH2-C=C-H

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Textbook Question

Predict the chemical shifts of the protons in the following compounds. (a)

In a 300-MHz spectrometer, the protons in iodomethane absorb at a position 650 Hz downfield from TMS. (a) What is the chemical shift of these protons? (b) What is the chemical shift of the iodomethane protons in a 60-MHz spectrometer? (c) How many hertz downfield from TMS would they absorb at 60 MHz?

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Textbook Question

Without referring to Table 14.1, label the proton or set of protons in each compound that gives the signal at the lowest frequency a, at the next lowest b, and so on. h.

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Textbook Question

Without referring to Table 14.1, label the proton or set of protons in each compound that gives the signal at the lowest frequency a, at the next lowest b, and so on. e.

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Textbook Question

Label each set of chemically equivalent protons, using a for the set that will be at the lowest frequency in the 1H NMR spectrum, b for the next lowest, and so on. Indicate the multiplicity of each signal. a.

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Textbook Question

Explain the relative chemical shifts of the benzene ring protons in Figure 14.18.

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Textbook Question

Without referring to Table 14.1, label the proton or set of protons in each compound that gives the signal at the lowest frequency a, at the next lowest b, and so on. c.

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Textbook Question

Explain why the chemical shift of the OH proton of a carboxylic acid is at a higher frequency than the chemical shift of an OH proton of an alcohol.

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Textbook Question

Which underlined proton (or sets of protons) has the greater chemical shift (that is, the higher frequency signal)? a.

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Textbook Question

Which underlined proton (or sets of protons) has the greater chemical shift (that is, the higher frequency signal)? c.

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Textbook Question

The methyl hydrogens in propane appear at a chemical shift of 0.9 ppm, whereas the methyl hydrogens of propene appear around 2.5 ppm. Explain.

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Textbook Question

Alkene hydrogens usually appear at similar chemical shifts between 5 and 6 ppm. The alkene hydrogens in the structure shown are very different. Rationalize the difference in chemical shifts between Hₐ and H₆ in the structure shown.

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Textbook Question

(•) For the following molecules, give the chemical shift for each indicated hydrogen. (d)

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Textbook Question

(•) For the following molecules, give the chemical shift for each indicated hydrogen. (e)

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Textbook Question

(•) For the following molecules, give the chemical shift for each indicated hydrogen. (b)

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Textbook Question

Compound A with molecular formula C6H10 has two peaks in its 1H NMR spectrum, both of which are singlets (with ratio 9 : 1). Compound A reacts with an acidic aqueous solution containing mercuric sulfate to form compound B, which gives a positive iodoform test (Problem 58) and has an 1H NMR spectrum that shows two singlets (with ratio 3 : 1). Identify A and B.

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Textbook Question

The 1H NMR chemical shifts of nitromethane, dinitromethane, and trinitromethane are at d 6.10, d 4.33, and d 7.52. Match each chemical shift with the compound. Explain how chemical shift correlates with pKa.

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Textbook Question

Which set of underlined hydrogens has its 1H NMR signal at a higher frequency? a. CH3CH2CH3 or CH3OCH2CH3 b. CH3CH=CH2 or CH3OCH=CH2

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Textbook Question

How would you expect the IR and ¹H NMR spectra for propanamide and N,N-diethylpropanamide to differ?

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Textbook Question

The chemical shifts of the C-2 hydrogen in the spectra of pyrrole, pyridine, and pyrrolidine are 2.82 ppm, 6.42 ppm, and 8.50 ppm. Match each heterocycle with its chemical shift.

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Textbook Question

[18]-Annulene shows two signals in its 1H NMR spectrum: one at 9.25 ppm and the other to the right of the TMS signal at -2.88 ppm. What hydrogens are responsible for each of the signals? (Hint: Look at the direction of the induced magnetic field outside and inside the benzene ring in Figure 14.6.)

An unknown compound (C₇H₆O) gives the IR spectrum shown here. At what chemical shifts would you expect to see signals in the ¹H NMR spectrum?

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Textbook Question

Predict the theoretical number of different NMR signals produced by each compound, and give approximate chemical shifts. Point out any diastereotopic relationships. (c) Ph—CHBr—CH2Br (d) vinyl chloride

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Textbook Question

b. Which pairs are diastereotopic hydrogens?

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Textbook Question

Predict the theoretical number of different NMR signals produced by each compound, and give approximate chemical shifts. Point out any diastereotopic relationships. (a) 2-bromobutane (b) cyclopentanol

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Multiple Choice

Which of the labeled hydrogens will be most de-shielded?

Which compound possesses a hydrogen with the highest chemical shift for its 1H NMR signal?

Which of the following chemical shift values could plausibly correspond to the protons in divinyl ether (CH₂=CH–O–CH=CH₂)

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Open Question

Which of the labeled protons absorbs energy most upfield in the 1H NMR?

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