How many signals would you expect to see in the 1 H NMR spectrum of each of the five compounds with molecular formula C 6 H 14 ?

All right. Hi, everyone. So for this question is asking us to determine the expected number of signals in the proton and M R spectrum for each structural isomer of C five H and they are and isophane and ne right. So option A says that N pentane has five signals, isophane has one and Neo Pentane has three. Option B says that N pentane has three signals. Isoptin has four signals. And opine has one signal. Option C says that N pentane has five signals. Isophane has five signals and Neo pentane has five signals. And option D says that N pentane has three signals. Isophane has five signals and Neo pentane has one signal. So for our reference, I've gone ahead and I've actually drawn out each isomer of C five H 12 on the bottom here. So we have N pentane isophane and neate. So if I scroll back up really quickly, let's recall that one signal or rather the number of total signals in a proton and M R spectrum corresponds to the number of protons in that molecule that are unique as I like to call it. And what I mean by unique is that each proton you see in the N M R spectrum is not chemically equivalent to others in the same spectrum. And it's important to bring up whether or not protons are chemically equivalent to one another because for example, when your molecule has an element of symmetry to it, that is actually going to reduce the number of signals that you expect to see because that reduces the number of chemically equivalent. Or rather it actually increases sorry, it increases the number of protons that are chemically equivalent to one another. Therefore reducing the number of signals. Now, specifically, if we start off with our first isomer here, our N pentane which is a straight chain of five carbons, then this does in fact have an element of symmetry to it because I can go ahead and draw a line, a dash line Down Carbon three here. And I would have the same thing on either side of my split. So the protons that are on either side of my split are actually going to be equivalent to the corresponding protons on the other side, right? So carbon three represents its own signal, But Carbons two and 4 are equivalent to each other, right? Because of the symmetry, therefore corresponding to another signal And carbons one in 5 likewise are equivalent to each other. So we actually have three signals for N pentane here. So now if we move on to isophane is, is going to have slightly more signals than end pending, right? Because we don't have a straightforward and element of symmetry here. So carbon one Right is going to correspond to one signal. Carbon two is going to correspond to another signal And carbon three is going to correspond to an additional signal. But Notice how we have carbon four here and a methyl substituent. But because both of them are bonded to the same carbon and they have the same number of protons, they are actually chemically equivalent to one another, Right. So instead of having five unique signals, we actually have four and I wrote that in the wrong color. So that has four signals. Now, if you want to talk about symmetry, we can definitely focus on our next isomer our opine as an example, right? Because we actually have two planes of symmetry. Great. So a Neo Pentin here has a vertical plain of symmetry and a horizontal plaintiff symmetry as well. So because of the two planes of symmetry here, each set of protons is actually going to be equivalent to the other, right. So all of these metal groups here correspond to just one signal in the N M R spectrum. So just as a recap, right, N. Pentane has three signals, isophane has four And Opine has one signal. So based on that right, our answer is going to be option B in the multiple choice. So if you stuck around to the end, thank you very much for watching and I hope you found this helpful.

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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

1H NMR:Number of Signals

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

1H NMR:Number of Signals

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Problem 3

Textbook Question

How many signals would you expect to see in the ¹H NMR spectrum of each of the five compounds with molecular formula C₆H₁₄?

Verified step by step guidance

Step 1: Understand the molecular formula C6H14. This is an alkane with six carbon atoms and 14 hydrogen atoms, meaning it is a saturated hydrocarbon. The compounds with this formula are structural isomers.

Step 2: Identify the five possible isomers of C6H14. These are: n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, and 2,3-dimethylbutane. Each isomer has a unique structure, which affects the number of unique hydrogen environments.

Step 3: Analyze the symmetry of each isomer to determine the number of unique hydrogen environments. Hydrogens in identical chemical environments will produce the same signal in the 1H NMR spectrum.

Step 4: For each isomer, count the unique hydrogen environments. For example, in n-hexane, all six carbons are in a straight chain, and the hydrogens on equivalent carbons will produce the same signal. In contrast, branched isomers like 2-methylpentane will have more unique environments due to reduced symmetry.

Step 5: Summarize the number of signals for each isomer. For example, n-hexane will have fewer signals compared to 2,2-dimethylbutane, which has more branching and thus more unique hydrogen environments. This step involves systematically analyzing each isomer's structure to determine the number of signals.

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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, such as hydrogen-1 (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 Environment

The chemical environment refers to the specific surroundings of a hydrogen atom within a molecule, which can influence its magnetic resonance signal. Factors such as electronegativity of nearby atoms, hybridization, and molecular symmetry affect the chemical shift observed in the NMR spectrum. Identifying unique environments helps predict the number of distinct signals in the spectrum.

Isomerism

Isomerism is the phenomenon where compounds share the same molecular formula but differ in structure or spatial arrangement. For the molecular formula C6H14, various structural isomers exist, such as straight-chain and branched alkanes. Each isomer can produce a different number of NMR signals due to variations in hydrogen environments, making it essential to consider isomerism when analyzing NMR data.

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