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

NMR Integration

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

NMR Integration

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Problem 19b

Textbook Question

For the molecules shown, give the number of signals expected and the relative ratio of the signal integrations.
(b)

Verified step by step guidance

Identify the unique hydrogen environments in the molecule. Each unique environment will give rise to a separate NMR signal.

Consider the symmetry of the molecule. Symmetrical molecules may have fewer unique hydrogen environments due to equivalent positions.

Count the number of hydrogens in each unique environment to determine the relative ratio of the signal integrations. This is because the area under each NMR signal is proportional to the number of hydrogens contributing to that signal.

Use the chemical structure to determine if any hydrogens are in similar electronic environments, which would result in them being equivalent and thus contributing to the same signal.

Summarize the number of signals and their relative integrations based on the analysis of unique hydrogen environments and their symmetry.

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Key Concepts

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

NMR Spectroscopy

Nuclear Magnetic Resonance (NMR) spectroscopy is a technique used to determine the structure of organic compounds by analyzing the magnetic properties of atomic nuclei. In NMR, different environments of hydrogen atoms (protons) in a molecule produce distinct signals, allowing chemists to infer the number and type of hydrogen environments present.

Chemical Shift

Chemical shift refers to the position of an NMR signal relative to a standard reference compound, typically tetramethylsilane (TMS). It provides information about the electronic environment surrounding a nucleus, with shifts influenced by factors such as electronegativity and hybridization of nearby atoms. Understanding chemical shifts helps predict the number of signals in an NMR spectrum.

Signal Integration

Signal integration in NMR spectroscopy quantifies the area under each signal peak, which corresponds to the number of protons contributing to that signal. The relative ratio of signal integrations reflects the proportion of different types of protons in the molecule, aiding in the determination of molecular structure by indicating how many protons are in each distinct environment.

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