Draw the 13 C NMR spectrum of each molecule in Assessment 15.48. (b)

Hey, everyone. And welcome back to another video, give approximate chemical shifts for all equivalent carbon sets in the illustrated molecule. We're given our chlorinated cyclic ether and we can use the carbon ear table to help us predict the chemical shifts. We don't have any internal plan of symmetry in this compound. So we can start labeling our carbons. What we notice is that A and B they are two metal groups that are bonded to carbon C. So they will represent one signal, then we have carbon C the FGNE. So all of these will be our unique signals A B then C defng. So now we can start assigning our approximate shift and B those are metal groups. So we can think about the CH which is in a range between 5 to 45 P PM. In this case, we're going to roughly take the middle of about 20 P PM because the metal groups are not attached to any electron withdrawing group right now, considering carbon sea, this is another ch but the main difference is that this ce H is methane, the previous one A and B, those were actually methyl groups, methane because it only has one hydrogen instead of three is expected at a higher end. So we can say, let's suppose 30 parts per million, right? Essentially, this is really important to remember the lower the number of carbon hydrogen bonds, the higher the P PM value because our carbon gets more, they shielded moving on to D that's another ch, but the main difference is that now the ch also has oxygen nearby, which is an electron withdrawing group X. So we expected between 30 to 80 P pm. And in addition to that, because it's once again, methane, we're going with a higher end and we can say it will be at about 90 P PM. Instead continuing with E E is very similar to D, they're almost symmetrical, but E is further the shielded by the adjacent chloral group. So we can say at about 95 B PM. Prior to clearly distinguish between D and E, we want to make sure that we at least add five PPM to indicate that there's an adjacent election withdrawing group. Now, we have a also for E we can say that it was Clch and F four F, we simply have our methylene group CH two. So we once again consider our ch that would be between five and 45. So because it's a siege two group, we can just once again go with around 30 parts per million for F that's perfectly fine. It will be very similar to C, right, we can say that it's slightly lower than 30 maybe 27 but we just want to approximate. So that's fine. And now for G we have another ch in this case, that's another siege two group, right? And we are going to say about 25 P PM. It's more shielded because it's further away from the election withdrawing chloral group. And that would be it. We have successfully assigned our approximate chemical shifts. Thank you for watching.

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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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Problem 49b

Textbook Question

Draw the ¹³C NMR spectrum of each molecule in Assessment 15.48.
(b)

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Identify the unique carbon environments in the molecule. Each unique environment will correspond to a different signal in the ¹³C NMR spectrum.

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

Determine the chemical shift range for each type of carbon. For example, sp³ hybridized carbons typically appear between 0-50 ppm, sp² hybridized carbons between 100-150 ppm, and carbonyl carbons around 160-220 ppm.

Consider the effects of electronegative atoms or groups nearby, which can deshield carbons and shift their signals downfield (to higher ppm values).

Sketch the spectrum, placing each signal at the appropriate chemical shift based on the analysis of the carbon environments and their electronic surroundings.

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Key Concepts

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

¹³C NMR Spectroscopy

¹³C NMR spectroscopy is a technique used to study the carbon atoms in organic molecules. It provides information about the number of unique carbon environments in a compound by measuring the resonance frequencies of carbon-13 nuclei in a magnetic field. Each distinct carbon environment typically appears as a separate peak in the spectrum, allowing for structural analysis of the molecule.

Chemical Shift

Chemical shift in NMR spectroscopy refers to the variation in the resonance frequency of a nucleus due to its electronic environment. In ¹³C NMR, chemical shifts are influenced by factors such as electronegativity of neighboring atoms and hybridization of the carbon atom. The chemical shift is measured in parts per million (ppm) and helps identify the type of carbon present in the molecule.

Multiplicity and Coupling

Multiplicity in NMR refers to the splitting of NMR signals into multiple peaks due to spin-spin coupling between neighboring nuclei. In ¹³C NMR, coupling with hydrogen atoms (¹H) can lead to splitting patterns, although often decoupled spectra are recorded to simplify analysis. Understanding coupling helps in deducing the connectivity and environment of carbon atoms in the molecule.

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