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:Number of Signals

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

1H NMR:Number of Signals

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5:16 minutes

Problem 78a(4,5,6)

Textbook Question

How many signals are produced by each of the following compounds in its
a. ¹H NMR spectrum?
4.
5.
6.

Verified step by step guidance

Analyze the structure of the compound: The molecule is a cyclobutane ring with two chlorine atoms attached. One chlorine is on a wedge (pointing out of the plane), and the other is on a dash (pointing into the plane). This indicates stereochemistry and suggests the molecule is chiral.

Determine the symmetry of the molecule: The presence of two different chlorine atoms on opposite sides of the cyclobutane ring breaks symmetry. This means the hydrogens on the ring are not equivalent and will produce distinct signals in the 1H NMR spectrum.

Identify the unique hydrogen environments: The hydrogens on the cyclobutane ring are in different environments due to the stereochemistry of the chlorine atoms. Each hydrogen will experience a different electronic environment depending on its proximity to the chlorine atoms and the spatial arrangement.

Consider the splitting patterns: Each unique hydrogen environment will produce a signal in the 1H NMR spectrum. The splitting of these signals will depend on the coupling between neighboring hydrogens, which is influenced by the ring strain and stereochemistry.

Count the number of signals: Based on the analysis, determine the number of unique hydrogen environments in the molecule. Each unique environment corresponds to a distinct signal in the 1H 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, primarily hydrogen (1H), to provide information about the number and environment of hydrogen atoms in a molecule. The resulting spectrum displays signals that correspond to different hydrogen environments, allowing chemists to infer structural details.

Chemical Shifts

Chemical shifts in NMR spectroscopy refer to the variation in resonance frequency of a nucleus due to its electronic environment. Different functional groups and neighboring atoms can cause shifts in the position of signals on the NMR spectrum. Understanding chemical shifts is crucial for interpreting the spectrum, as they help identify the types of hydrogen atoms present and their relative positions in the molecule.

Signal Multiplicity

Signal multiplicity in NMR refers to the splitting of a signal into multiple peaks, which occurs due to spin-spin coupling between neighboring hydrogen atoms. The number of peaks in a signal can provide insight into the number of adjacent hydrogen atoms (n+1 rule). Recognizing the multiplicity of signals is essential for deducing the connectivity and arrangement of atoms within a compound.

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