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

Structure Determination without Mass Spect

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

Structure Determination without Mass Spect

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6:39 minutes

Problem 8

Textbook Question

The proton and ¹³C NMR spectra of a compound of formula C₄H₁₁N are shown here. Determine the structure of this amine, and give peak assignments for all of the protons in the structure.
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Verified step by step guidance

Step 1: Analyze the molecular formula C4H11N. This indicates the compound is an amine with one nitrogen atom and a total of 11 hydrogens distributed across the structure.

Step 2: Examine the proton (1H) NMR spectrum. The peaks are labeled with integration values: 6H at around 1 ppm, 2H at around 3 ppm, and 1H at around 5 ppm. These integration values correspond to the number of protons contributing to each signal.

Step 3: Interpret the splitting patterns in the proton NMR. The peak at 1 ppm (6H) is likely a singlet, indicating equivalent protons with no neighboring protons. The peak at 3 ppm (2H) may show splitting due to adjacent protons, suggesting a CH2 group. The peak at 5 ppm (1H) is likely a singlet, indicating a proton attached to the nitrogen atom.

Step 4: Examine the 13C NMR spectrum. The spectrum shows two distinct carbon signals, indicating two unique carbon environments. This supports the idea of symmetry in the molecule.

Step 5: Based on the NMR data, propose a structure for the amine. The integration values and splitting patterns suggest the compound is likely isopropylamine (CH3)2CHNH2. Assign the peaks: the 6H signal corresponds to the two CH3 groups, the 2H signal corresponds to the CH group, and the 1H signal corresponds to the NH2 group.

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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 protons and carbon-13, to provide information about the environment surrounding these nuclei. The resulting spectra reveal chemical shifts, which indicate the electronic environment of the atoms, allowing chemists to deduce structural information about the compound.

Chemical Shifts

Chemical shifts in NMR spectroscopy refer to the variation in resonance frequency of a nucleus due to its electronic environment. They are measured in parts per million (ppm) and provide insight into the types of hydrogen or carbon atoms present in a molecule. Understanding chemical shifts is crucial for assigning peaks in the NMR spectrum to specific protons or carbons, which aids in elucidating the compound's structure.

Peak Assignments

Peak assignments in NMR involve correlating the observed peaks in the spectrum to specific protons or carbon atoms in the molecular structure. This process requires knowledge of the expected chemical shifts for different functional groups and the splitting patterns that arise from neighboring protons (spin-spin coupling). Accurate peak assignments are essential for constructing a complete and correct structural representation of the compound.

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Related Practice

Textbook Question

The spectral data below are presented in a manner similar to what you would find in a chemistry research journal. Identify the structure for each set of data.

(c) C₇H₁₄O₂ : ¹H NMR: δ 0.91 (3H, t, J = 7.0 Hz), 1.11 (6H, d, J = 7.0 Hz), 1.82 (2H, sextet), 2.40 (1H, sept, J = 7.0 Hz), 4.14 (2H, t, J = 7.1 Hz); IR (cm ⁻¹) : 1745, 1200

Textbook Question

A compound gives the following IR spectrum. Upon reaction with sodium borohydride followed by acidification, it forms the product with the ¹H NMR spectrum shown below. Identify the starting material and the product.

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Textbook Question

Shown below is the ¹H NMR spectrum of the alkyl bromide used to make the phosphonium ylide that reacts with a ketone in a Wittig reaction to form a compound with molecular formula C₁₁H₁₄. What product is obtained from the Wittig reaction?

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Textbook Question

An aromatic hydrocarbon with a molecular formula of C₁₃H₂₀ has an ¹H NMR spectrum with a signal at ~7 ppm that integrates to 5H. It also has two singlets; one of the singlets has 1.5 times the area of the second. What is the structure of the aromatic hydrocarbon?

Textbook Question

Identify each of the following compounds from its molecular formula and its IR and ¹H NMR spectra:

b. C₆H₁₂O₂

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Textbook Question

Identify each of the following compounds from its molecular formula and its IR and ¹H NMR spectra:

b.C₆H₁₄O

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Textbook Question

A compound with molecular formula C₅H₁₀O₂ gives the following IR spectrum. When it undergoes acid-catalyzed hydrolysis, the compound with the ¹H NMR spectrum shown below is formed. Identify the compounds.

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Textbook Question

An unknown compound (C₃H₂NCl) shows moderately strong IR absorptions around 1650 cm^–1 and 2200 cm^–1. Its NMR spectrum consists of two doublets (J = 14 Hz) at δ5.9 and δ7.1. Propose a structure consistent with these data.

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The proton and 13C NMR spectra of a compound of formula C4H11N are shown here. Determine the structure of this amine, and give peak assignments for all of the protons in the structure.<IMAGE>

Key Concepts

Nuclear Magnetic Resonance (NMR) Spectroscopy

Chemical Shifts

Peak Assignments

Watch next

The proton and ¹³C NMR spectra of a compound of formula C₄H₁₁N are shown here. Determine the structure of this amine, and give peak assignments for all of the protons in the structure.
<IMAGE>