Chemistry
Chemistry
10th Edition
ISBN: 9781305957404
Author: Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher: Cengage Learning
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### Identifying an Unknown Acetate Ester Using NMR

The NMR of an unknown acetate ester formed from a six-carbon alcohol is shown below along with six possible candidates.

Identify the ester candidate that corresponds to the NMR spectrum. Justify your answer by showing how the other five candidates can be eliminated based on all three points below. No peak assignments are necessary for this problem.

1. **Integration ratio of the two most downfield signals**
   
2. **Peak multiplicity of the most downfield signal**
   
3. **Peak multiplicity and/or integration of the most upfield signal(s)**
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Transcribed Image Text:### Identifying an Unknown Acetate Ester Using NMR The NMR of an unknown acetate ester formed from a six-carbon alcohol is shown below along with six possible candidates. Identify the ester candidate that corresponds to the NMR spectrum. Justify your answer by showing how the other five candidates can be eliminated based on all three points below. No peak assignments are necessary for this problem. 1. **Integration ratio of the two most downfield signals** 2. **Peak multiplicity of the most downfield signal** 3. **Peak multiplicity and/or integration of the most upfield signal(s)**
### Nuclear Magnetic Resonance (NMR) Spectroscopy

Below is an example of an NMR spectrum followed by structural formulas of various ester compounds. NMR spectroscopy is a powerful analytical technique used to determine the structure of organic compounds by identifying the environment of hydrogen atoms (protons) in a molecule.

#### NMR Spectrum Interpretation

The NMR spectrum shown consists of multiple peaks, each corresponding to protons in different environments within the molecules. The x-axis represents the chemical shift in parts per million (PPM). The chemical shift provides information about the electronic environment surrounding the protons. The y-axis, although typically indicating the signal intensity, is not labeled in this image but illustrates the number of protons in each environment proportional to the peak height.

###### Key Observations:

1. **Chemical Shift at 5 PPM**:
   - **Multiplet Peak** indicating a complex splitting pattern.
   - Integral value of **1H** (1 proton).

2. **Chemical Shifts around 3-4 PPM**:
   - **Singlet Peaks** surrounded by **multiplets**.
   - Integral values of **3H**, **1H**, and **2H** suggest different proton environments.

3. **Chemical Shifts between 1-2 PPM**:
   - **Multiplet Peaks** with integral values indicating **3H**, **1H**, and **6H**, highlighting the presence of more shielded protons in different environments.

#### Structural Formulas

Six ester compounds are given with their corresponding labels:

1. **E1**:
   - Structural formula: ![E1](https://chem.nlm.nih.gov/chemidplus/structure/SDF/7053-36-5.sdf)
   - Simple ester with a propyl chain.

2. **E2**:
   - Structural formula: ![E2](https://chem.nlm.nih.gov/Chemidplus/structure/SDF/623-27-8.sdf)
   - Ester with two methyl groups attached to the alpha carbon.
  
3. **E3**:
   - Structural formula: ![E3](https://chem.nlm.nih.gov/chemidplus/structure/SDF/636-58-8.sdf)
   - Ester with a t-butyl group attached to the alpha carbon.
  
4. **E4**:
   - Structural formula: ![E4](https://chem.nlm.nih
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Transcribed Image Text:### Nuclear Magnetic Resonance (NMR) Spectroscopy Below is an example of an NMR spectrum followed by structural formulas of various ester compounds. NMR spectroscopy is a powerful analytical technique used to determine the structure of organic compounds by identifying the environment of hydrogen atoms (protons) in a molecule. #### NMR Spectrum Interpretation The NMR spectrum shown consists of multiple peaks, each corresponding to protons in different environments within the molecules. The x-axis represents the chemical shift in parts per million (PPM). The chemical shift provides information about the electronic environment surrounding the protons. The y-axis, although typically indicating the signal intensity, is not labeled in this image but illustrates the number of protons in each environment proportional to the peak height. ###### Key Observations: 1. **Chemical Shift at 5 PPM**: - **Multiplet Peak** indicating a complex splitting pattern. - Integral value of **1H** (1 proton). 2. **Chemical Shifts around 3-4 PPM**: - **Singlet Peaks** surrounded by **multiplets**. - Integral values of **3H**, **1H**, and **2H** suggest different proton environments. 3. **Chemical Shifts between 1-2 PPM**: - **Multiplet Peaks** with integral values indicating **3H**, **1H**, and **6H**, highlighting the presence of more shielded protons in different environments. #### Structural Formulas Six ester compounds are given with their corresponding labels: 1. **E1**: - Structural formula: ![E1](https://chem.nlm.nih.gov/chemidplus/structure/SDF/7053-36-5.sdf) - Simple ester with a propyl chain. 2. **E2**: - Structural formula: ![E2](https://chem.nlm.nih.gov/Chemidplus/structure/SDF/623-27-8.sdf) - Ester with two methyl groups attached to the alpha carbon. 3. **E3**: - Structural formula: ![E3](https://chem.nlm.nih.gov/chemidplus/structure/SDF/636-58-8.sdf) - Ester with a t-butyl group attached to the alpha carbon. 4. **E4**: - Structural formula: ![E4](https://chem.nlm.nih
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