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Why does the 1H-NMR spectrum of the product only show “singlets”? materials used: 1.15 g of 1,4-dimethoxybenzene 2.2 mL of tert.-butyl alcohol 3.4 mL glacial acetic acid 4.50 mL of concentrated sulfuric acid Product characterization: 0.77 g of the final product

Why does the 1H-NMR spectrum of the product only show “singlets”? materials used: 1.15 g of 1,4-dimethoxybenzene 2.2 mL of tert.-butyl alcohol 3.4 mL glacial acetic acid 4.50 mL of concentrated sulfuric acid Product characterization: 0.77 g of the final product

Chemistry
Chemistry
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ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
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Experiment: Friedel-Crafts Alkylation

Question: Why does the 1H-NMR spectrum of the product only show “singlets”?

materials used:

  • 1.15 g of 1,4-dimethoxybenzene

  • 2.2 mL of tert.-butyl alcohol

  • 3.4 mL glacial acetic acid

  • 4.50 mL of concentrated sulfuric acid

Product characterization:

    • 0.77 g of the final product
In the current experiment, we will use a different electrophile (the tert-butyl cation) to alkylate 1,4-dimethoxybenzene. This is a Friedel-Crafts Alkylation reaction. **Chemical Reaction Description:** - **Reactant Structure:** - The left side of the reaction shows 1,4-dimethoxybenzene with methoxy groups (OCH₃ and H₃CO) attached to a benzene ring. - **Reaction Conditions:** - Above the reaction arrow: (CH₃)₃COH - Below the reaction arrow: CH₃COOH/H₂SO₄ - **Product Structure:** - The right side of the reaction shows the product with two tert-butyl groups ((H₃C)₃C and C(CH₃)₃) now attached to the benzene ring, along with the existing methoxy groups (OCH₃ and H₃CO).
Transcribed Image Text:In the current experiment, we will use a different electrophile (the tert-butyl cation) to alkylate 1,4-dimethoxybenzene. This is a Friedel-Crafts Alkylation reaction. **Chemical Reaction Description:** - **Reactant Structure:** - The left side of the reaction shows 1,4-dimethoxybenzene with methoxy groups (OCH₃ and H₃CO) attached to a benzene ring. - **Reaction Conditions:** - Above the reaction arrow: (CH₃)₃COH - Below the reaction arrow: CH₃COOH/H₂SO₄ - **Product Structure:** - The right side of the reaction shows the product with two tert-butyl groups ((H₃C)₃C and C(CH₃)₃) now attached to the benzene ring, along with the existing methoxy groups (OCH₃ and H₃CO).
**NMR Spectra Analysis** The image displays an NMR (Nuclear Magnetic Resonance) spectrum obtained using CDCl₃ as the solvent. The spectrum includes both \(^{1}\)H-NMR, performed at 400 MHz, and \(^{13}\)C-NMR at 100 MHz. ### Key Features: #### Peaks: - **Chemical Shift** (ppm) - **1.32 ppm**: This peak is likely associated with a simple alkyl hydrogen environment. - **1.38 ppm**: Another peak in a similar region, possibly indicative of a nearby hydrogen environment. - **3.68 ppm**: Suggests the presence of a hydrogen in a more electronegative environment, possibly near oxygen or nitrogen. - **7.26 ppm**: This peak falls within the aromatic region, indicating hydrogen atoms attached to an aromatic ring. #### Spectrum Details: - **Horizontal Axis (f1 ppm):** This represents the chemical shift in parts per million (ppm), a unit that shows where the nucleus resonates relative to a standard reference. Chemical shifts give insights into the electronic environment of the nuclei. - **Vertical Tick Marks:** These are indicative of the integration of peaks, which help in determining the relative number of protons contributing to each signal. Analyzing this NMR spectrum can provide insights into the molecular structure of the compound being studied. The specific chemical shifts, peak integration, and splitting patterns (not visible in this image) allow chemists to deduce the environment around specific hydrogen atoms and piece together structural information. ### Note: For a full structural determination, combining \(^{1}\)H-NMR data with other spectroscopic techniques like \(^{13}\)C-NMR, IR, and mass spectrometry is often required.
Transcribed Image Text:**NMR Spectra Analysis** The image displays an NMR (Nuclear Magnetic Resonance) spectrum obtained using CDCl₃ as the solvent. The spectrum includes both \(^{1}\)H-NMR, performed at 400 MHz, and \(^{13}\)C-NMR at 100 MHz. ### Key Features: #### Peaks: - **Chemical Shift** (ppm) - **1.32 ppm**: This peak is likely associated with a simple alkyl hydrogen environment. - **1.38 ppm**: Another peak in a similar region, possibly indicative of a nearby hydrogen environment. - **3.68 ppm**: Suggests the presence of a hydrogen in a more electronegative environment, possibly near oxygen or nitrogen. - **7.26 ppm**: This peak falls within the aromatic region, indicating hydrogen atoms attached to an aromatic ring. #### Spectrum Details: - **Horizontal Axis (f1 ppm):** This represents the chemical shift in parts per million (ppm), a unit that shows where the nucleus resonates relative to a standard reference. Chemical shifts give insights into the electronic environment of the nuclei. - **Vertical Tick Marks:** These are indicative of the integration of peaks, which help in determining the relative number of protons contributing to each signal. Analyzing this NMR spectrum can provide insights into the molecular structure of the compound being studied. The specific chemical shifts, peak integration, and splitting patterns (not visible in this image) allow chemists to deduce the environment around specific hydrogen atoms and piece together structural information. ### Note: For a full structural determination, combining \(^{1}\)H-NMR data with other spectroscopic techniques like \(^{13}\)C-NMR, IR, and mass spectrometry is often required.
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