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

1H NMR:Spin-Splitting Complex Tree Diagrams

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

1H NMR:Spin-Splitting Complex Tree Diagrams

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Problem 40a

Textbook Question

Draw the expected signal for a hydrogen with the following coupling constants.
(a) Hₐ : δ 5.34 (Jₐ꜀ = 12 , Jₐ₆ = 2)

Verified step by step guidance

Identify the type of hydrogen environment: The hydrogen Hₐ is located at δ 5.34 ppm, which suggests it is in an alkene or aromatic environment.

Understand the coupling constants: Jₐ꜀ = 12 Hz indicates a trans coupling, typical for alkenes, while Jₐ₆ = 2 Hz suggests a long-range or allylic coupling.

Determine the splitting pattern: The hydrogen Hₐ will be split into a doublet of doublets due to the two different coupling constants.

Draw the signal: Start by drawing a doublet with a splitting of 12 Hz, then split each of these peaks further into doublets with a splitting of 2 Hz.

Label the peaks: Ensure that the peaks are labeled with the correct coupling constants, showing the larger splitting (12 Hz) and the smaller splitting (2 Hz).

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Key Concepts

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

Chemical Shift (δ)

Chemical shift (δ) is a measure of the resonance frequency of a nucleus relative to a standard in a magnetic field. It is expressed in parts per million (ppm) and provides information about the electronic environment surrounding the nucleus. In this question, δ 5.34 indicates the position of the hydrogen signal on the NMR spectrum.

Coupling Constant (J)

The coupling constant (J) is a parameter that quantifies the interaction between nuclear spins in NMR spectroscopy, resulting in signal splitting. It is measured in Hertz (Hz) and reflects the strength of spin-spin coupling. Jₐ꜀ = 12 Hz and Jₐ₆ = 2 Hz indicate the splitting pattern of the hydrogen signal due to interactions with neighboring nuclei.

Signal Multiplicity

Signal multiplicity refers to the number of peaks observed in an NMR signal due to spin-spin coupling. It is determined by the number of neighboring hydrogen atoms and their coupling constants. In this question, the hydrogen signal will be split into a pattern based on the given coupling constants, indicating the presence of adjacent hydrogen atoms.

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Master Splitting with J-Values:Complex Tree Diagram with a bite sized video explanation from Johnny

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Related Practice

Open Question

Draw a tree diagram for H* in the structure below.

F₂CH*CH(CH₃)₂ J_H*-F = 50 Hz

J_H*-H = 7 Hz

Textbook Question

The spectrum of trans-hex-2-enoic acid follows.

(a) Assign peaks to show which protons give rise to which peaks in the spectrum.

(b) Draw a tree to show the complex splitting of the vinyl proton centered around 7 ppm. Estimate the values of the coupling constants.

Textbook Question

Draw a splitting diagram for the H_b proton if J_bc = 10 and J_ba = 5.

Textbook Question

Draw a splitting tree, similar to Figures 13-32 and 13-33, for proton H^c in styrene. What is the chemical shift of proton H^c?

Textbook Question

What coupling constant would you expect between Hₐ and H₆ in cyclopent-2-en-1-one?

Textbook Question

Draw a diagram like the one shown in Figure 14.12 to predict

b. the relative intensities of the peaks in a quintet.

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Textbook Question

Draw a splitting diagram for H_b, where

a. J_ba = 12 Hz and J_bc = 6 Hz.

Textbook Question

Using a 60-MHz spectrometer, a chemist observes the following absorption: doublet, J = 7 Hz, at δ4.00

(a) What would the chemical shift (δ) be in the 300-MHz spectrum?

(b) What would the splitting value J be in the 300-MHz spectrum?

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Draw the expected signal for a hydrogen with the following coupling constants.(a) Hₐ : δ 5.34 (Jₐ꜀ = 12 , Jₐ₆ = 2)

Key Concepts

Chemical Shift (δ)

Coupling Constant (J)

Signal Multiplicity

Watch next

Draw the expected signal for a hydrogen with the following coupling constants.
(a) Hₐ : δ 5.34 (Jₐ꜀ = 12 , Jₐ₆ = 2)