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 Practice

Organic Chemistry

15. Analytical Techniques:IR, NMR, Mass Spect

NMR Practice

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Problem 77d

Textbook Question

Identify each of the following compounds from its molecular formula and its IR and ¹H NMR spectra:
d. C₁₁H₁₄O₂
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Verified step by step guidance

Analyze the molecular formula (C11H14O2): Calculate the degree of unsaturation using the formula: \( ext{Degree of Unsaturation} = rac{2C + 2 - H + N - X}{2} \), where C = number of carbons, H = number of hydrogens, N = number of nitrogens, and X = number of halogens. This will help determine the presence of rings or double bonds in the structure.

Examine the IR spectrum: Look for key functional group absorptions. For example, a strong absorption around 1700 cm⁻¹ indicates a carbonyl group (C=O), while a broad absorption around 3200-3600 cm⁻¹ suggests an -OH group. Identify any other significant peaks that could indicate functional groups like ethers, esters, or aromatic rings.

Interpret the 1H NMR spectrum: Analyze the chemical shifts, splitting patterns, and integration values. For example, chemical shifts around 6-8 ppm suggest aromatic protons, while shifts around 2-4 ppm could indicate protons near electronegative atoms or in an alpha position to a carbonyl group. Use the integration values to determine the number of protons contributing to each signal.

Combine the information: Use the molecular formula, degree of unsaturation, IR data, and 1H NMR data to piece together the structure. For example, if the IR spectrum shows a carbonyl group and the NMR spectrum indicates aromatic protons, consider the possibility of an aromatic ester or ketone.

Propose the structure: Based on the combined data, propose a structure that matches the molecular formula, degree of unsaturation, and spectral data. Verify that the structure accounts for all observed peaks in the IR and NMR spectra and satisfies the molecular formula.

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Key Concepts

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

Molecular Formula Interpretation

The molecular formula provides essential information about the number and types of atoms in a compound. For C11H14O2, it indicates the presence of 11 carbon atoms, 14 hydrogen atoms, and 2 oxygen atoms. Understanding how to interpret this formula is crucial for deducing the compound's structure and potential functional groups.

Infrared (IR) Spectroscopy

IR spectroscopy is a technique used to identify functional groups in a molecule based on the absorption of infrared light. Different bonds absorb characteristic wavelengths, allowing chemists to infer the presence of specific functional groups, such as alcohols, carbonyls, or esters, which can be crucial for identifying the compound represented by the molecular formula.

Proton Nuclear Magnetic Resonance (1H NMR) Spectroscopy

1H NMR spectroscopy provides information about the hydrogen atoms in a molecule, revealing their environment and connectivity. The chemical shifts, splitting patterns, and integration of peaks in the NMR spectrum help determine the number of hydrogen atoms in different environments, aiding in the elucidation of the compound's structure and confirming its identity.

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1H NMR Integration

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Related Practice

Textbook Question

Identify each compound from its molecular formula and its ¹H NMR spectrum:

b. C₅H₁₀O

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Textbook Question

Describe the ¹H NMR spectrum you would expect for each of the following compounds, indicating the relative positions of the signals:

Textbook Question

The following ¹H NMR spectra are for four compounds, each with molecular formula of C₆H₁₂O₂. Identify the compounds.

d. <IMAGE>

Textbook Question

When compound A (C₅H₁₂O) is treated with HBr, it forms compound B (C₅H₁₁Br). The ¹H NMR spectrum of compound A has a 1H singlet, a 3H doublet, a 6H doublet, and two 1H multiplets. The ¹H NMR spectrum of compound B has a 6H singlet, a 3H triplet, and a 2H quartet. Identify compounds A and B.

Textbook Question

In the lab, ¹H NMR is often used to verify that a reaction has worked as expected by comparing the product spectrum with what is expected. Given the ¹H NMR of the reactant shown, draw the spectrum you'd expect to see of the product that results.

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Textbook Question

(a) Using the ¹H NMR spectra, identify the reactants and product for this reaction.

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Textbook Question

(b) Provide an arrow-pushing mechanism for the reaction.

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Textbook Question

Without worrying about the relative location of the signals (i.e., the chemical shift) or the splitting patterns, draw a spectrum of the following molecule, being sure to indicate the integration of each peak. Label each signal based on the set of equivalent hydrogens to which it corresponds. [We expand on this question in future assessments.]

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Identify each of the following compounds from its molecular formula and its IR and 1H NMR spectra: d. C11H14O2<IMAGE>

Key Concepts

Molecular Formula Interpretation

Infrared (IR) Spectroscopy

Proton Nuclear Magnetic Resonance (1H NMR) Spectroscopy

Identify each of the following compounds from its molecular formula and its IR and ¹H NMR spectra:
d. C₁₁H₁₄O₂
<IMAGE>