Answered: 3C: C5H10O2 100 88 68 40 4.0 3H 2500 2H…

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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$### NMR Spectroscopy Tutorial This section covers the principles of Nuclear Magnetic Resonance (NMR) spectroscopy and provides a step-by-step problem-solving guide including an example with corresponding spectrum analysis. #### Task Requirements: For each problem, you are required to: 1. **Calculate the Degree of Unsaturation:** Determine the number of rings and/or multiple bonds in the compound. 2. **Assign the Principal IR Absorption Bands Above 1500 cm<sup>-1</sup>:** Identify the significant functional groups present in the compound using IR spectroscopy data. 3. **Draw the Structure of the Compound:** Use the provided data to sketch the molecular structure. 4. **Label the Protons on Your Structure:** Assign letters to the different types of protons in your structure and correlate them to the peaks on the NMR spectrum. An example is provided below for clarity. #### Example Analysis Consider the provided NMR spectrum and the molecular structure example: **Molecular Structure:** - The molecular structure depicted includes a hydroxyl group (-OH) attached to an alkyl chain. - The structure is labeled with letters (A, B, C, D) to denote different proton environments. **NMR Spectrum:** The NMR spectrum shows several peaks, which are explained as follows: - **Peak A:** At approximately 1.0 ppm, corresponds to 3 protons. This is typically indicative of a methyl group ($CH_3 $). - **Peak B:** At approximately 1.5 ppm, corresponds to 2 protons. This is indicative of a methylene group ($CH_2 $) adjacent to another $-CH_2$ group. - **Peak C:** At approximately 3.5 ppm, corresponds to 2 protons. This is indicative of a methylene group ($CH_2 $) adjacent to an electronegative atom such as oxygen. - **Peak D:** At approximately 2.5 ppm, corresponds to 1 proton. This is indicative of a proton on a carbon attached to an electronegative atom, such as a hydroxyl group ($OH$). The x-axis of the NMR spectrum is given in parts per million (ppm), ranging from 0.5 to 4.0 ppm, presenting a detailed profile of the proton environments in the compound: - 4.0 to 3.0 ppm: Contains peak C. - 2.5 to$

Transcribed Image Text:### NMR Spectroscopy Tutorial This section covers the principles of Nuclear Magnetic Resonance (NMR) spectroscopy and provides a step-by-step problem-solving guide including an example with corresponding spectrum analysis. #### Task Requirements: For each problem, you are required to: 1. **Calculate the Degree of Unsaturation:** Determine the number of rings and/or multiple bonds in the compound. 2. **Assign the Principal IR Absorption Bands Above 1500 cm<sup>-1</sup>:** Identify the significant functional groups present in the compound using IR spectroscopy data. 3. **Draw the Structure of the Compound:** Use the provided data to sketch the molecular structure. 4. **Label the Protons on Your Structure:** Assign letters to the different types of protons in your structure and correlate them to the peaks on the NMR spectrum. An example is provided below for clarity. #### Example Analysis Consider the provided NMR spectrum and the molecular structure example: **Molecular Structure:** - The molecular structure depicted includes a hydroxyl group (-OH) attached to an alkyl chain. - The structure is labeled with letters (A, B, C, D) to denote different proton environments. **NMR Spectrum:** The NMR spectrum shows several peaks, which are explained as follows: - **Peak A:** At approximately 1.0 ppm, corresponds to 3 protons. This is typically indicative of a methyl group ($CH_3 $). - **Peak B:** At approximately 1.5 ppm, corresponds to 2 protons. This is indicative of a methylene group ($CH_2 $) adjacent to another $-CH_2$ group. - **Peak C:** At approximately 3.5 ppm, corresponds to 2 protons. This is indicative of a methylene group ($CH_2 $) adjacent to an electronegative atom such as oxygen. - **Peak D:** At approximately 2.5 ppm, corresponds to 1 proton. This is indicative of a proton on a carbon attached to an electronegative atom, such as a hydroxyl group ($OH$). The x-axis of the NMR spectrum is given in parts per million (ppm), ranging from 0.5 to 4.0 ppm, presenting a detailed profile of the proton environments in the compound: - 4.0 to 3.0 ppm: Contains peak C. - 2.5 to

**Sample Identification: 3C: C<sub>5</sub>H<sub>10</sub>O<sub>2</sub>**

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### IR Spectrum Analysis:

The provided IR (Infrared) spectrum displays various absorption peaks, which correspond to different vibrational modes of the molecular bonds in the compound. The x-axis represents the wavenumber (cm<sup>-1</sup>), ranging from 4000 to 500 cm<sup>-1</sup>, while the y-axis represents the transmittance (%).

Key absorption peaks and their corresponding wavenumbers are marked on the spectrum:
- **2968 cm<sup>-1</sup>:** Likely corresponding to C-H stretching vibrations.
- **2870 cm<sup>-1</sup>:** Typically indicative of C-H stretching.
- **1741 cm<sup>-1</sup>:** Represents the C=O stretching vibration, suggesting the presence of a carbonyl group.
- **1467 cm<sup>-1</sup>:** Corresponds to C-H bending vibrations.
- **1381 cm<sup>-1</sup>:** Possibly related to methyl (-CH₃) bending.
- **1259 cm<sup>-1</sup> and 1197 cm<sup>-1</sup>:** C-O stretching in esters and ethers.
- **1097 cm<sup>-1</sup>:** Another band possibly due to C-O stretching.

### NMR Spectrum Analysis:

The NMR (Nuclear Magnetic Resonance) spectrum provides information about the hydrogen (proton) environment in the compound. The x-axis shows the chemical shifts (δ) in parts per million (ppm), ranging from 0 to 4.5 ppm, while the y-axis intensity is not specified.

Key points from the NMR spectrum indicating the proton environments:
- **~1.0 ppm (3H at two separate peaks):** Likely indicative of methyl groups (CH₃).
- **~1.9 ppm and ~2.1 ppm (2H each):** Corresponds to methylene groups (CH₂) in different environments.
- **~3.5 ppm (3H):** Suggests the presence of a methoxy group (OCH₃).

### Interpretation:

The IR and NMR spectra combined suggest the presence of functional groups and molecular environments consistent with an ester. The significant peaks around 1741 cm<

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3C: C5H10O2 100 88 68 40 4.0 3H 2500 2H 2008 2.0 1741 2H illu 1437 1500 1259- 1197 3H num T 0.5 PPM