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groups in aspirin absorbing at different wavenumbers? 3. Below is the NMR spectrum of aspirin with signals in regions A, B, and C. Analyze the spectrum by drawing the structure of aspirin and labeling each H with the letter (A through C) to show which signal is produced by which H. 14 C 12 10 B 8 A 0 ppm

groups in aspirin absorbing at different wavenumbers? 3. Below is the NMR spectrum of aspirin with signals in regions A, B, and C. Analyze the spectrum by drawing the structure of aspirin and labeling each H with the letter (A through C) to show which signal is produced by which H. 14 C 12 10 B 8 A 0 ppm

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
Chapter1: Chemical Foundations
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Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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46 EXPERIMENT 5: PREPARATION OF ASPIRIN the product and then recrystallize it from ethanol/water. Obtain the melting point of the recrystallized product. Finally, weigh the crystals and then determine the % yield based on mass of the sample you are turning in. If you had to do a recrystallization, also calculate the % recovery for the recrystallization step. If recrystallization is not necessary, go to step 4. 4. Obtain an IR spectrum using the Buck single beam IR spectrometer. Be sure to get the computer to read precise wavenumbers for all the major and/or relevant peaks. Place a couple of small crystals of the aspirin in a vial and dissolve it in a few drops of methylene chloride (CH₂Cl2). A couple of drops of this solution is placed on the optical reflectance platform, and the solvent evaporated. This produces very tiny crystals on the platform so that the IR beam reflects off the crystals. Run the spectrum and have the computer subtract the background. 5. To check for unreacted salicylic acid in your product, take a small amount of the crystals and put them in a test tube and add several drops of an aqueous FeCl3 solution. Look for the appearance of a dark purple color. If no color appears, then the product contains no unreacted salicylic acid. Record your test results in your notebook and lab report. Conduct this test with some salicylic acid to see what a positive test looks like. Record your observations. Turn in your sample of aspirin in a properly labeled polyethylene bag. In your lab report, interpret your IR, compare the experimental MP with what is reported in the literature, and discuss the results of the FeCl3 test. NOTE: If you obtained an IR spectrum of a solid from the Internet, always check to see whether it is done as a KBr disc, CCl4 solution or as a nujol mull. Absorptions shown may be due to the medium rather than the sample itself. It is best to find a spectrum done as a KBr disc, as KBr is transparent in the IR range. Post-Lab Questions: 1. How do you account for the smell of vinegar when an old bottle of aspirin is opened? 2. The carbonyls of ketones are expected to absorb around 1715 cm-¹. Why are the two carbonyl groups in aspirin absorbing at different wavenumbers? 3. Below is the NMR spectrum of aspirin with signals in regions A, B, and C. Analyze the spectrum by drawing the structure of aspirin and labeling each H with the letter (A through C) to show which signal is produced by which H. 14 C B N 12 10 8 A 2 0 ppm FRYDE
Transcribed Image Text:46 EXPERIMENT 5: PREPARATION OF ASPIRIN the product and then recrystallize it from ethanol/water. Obtain the melting point of the recrystallized product. Finally, weigh the crystals and then determine the % yield based on mass of the sample you are turning in. If you had to do a recrystallization, also calculate the % recovery for the recrystallization step. If recrystallization is not necessary, go to step 4. 4. Obtain an IR spectrum using the Buck single beam IR spectrometer. Be sure to get the computer to read precise wavenumbers for all the major and/or relevant peaks. Place a couple of small crystals of the aspirin in a vial and dissolve it in a few drops of methylene chloride (CH₂Cl2). A couple of drops of this solution is placed on the optical reflectance platform, and the solvent evaporated. This produces very tiny crystals on the platform so that the IR beam reflects off the crystals. Run the spectrum and have the computer subtract the background. 5. To check for unreacted salicylic acid in your product, take a small amount of the crystals and put them in a test tube and add several drops of an aqueous FeCl3 solution. Look for the appearance of a dark purple color. If no color appears, then the product contains no unreacted salicylic acid. Record your test results in your notebook and lab report. Conduct this test with some salicylic acid to see what a positive test looks like. Record your observations. Turn in your sample of aspirin in a properly labeled polyethylene bag. In your lab report, interpret your IR, compare the experimental MP with what is reported in the literature, and discuss the results of the FeCl3 test. NOTE: If you obtained an IR spectrum of a solid from the Internet, always check to see whether it is done as a KBr disc, CCl4 solution or as a nujol mull. Absorptions shown may be due to the medium rather than the sample itself. It is best to find a spectrum done as a KBr disc, as KBr is transparent in the IR range. Post-Lab Questions: 1. How do you account for the smell of vinegar when an old bottle of aspirin is opened? 2. The carbonyls of ketones are expected to absorb around 1715 cm-¹. Why are the two carbonyl groups in aspirin absorbing at different wavenumbers? 3. Below is the NMR spectrum of aspirin with signals in regions A, B, and C. Analyze the spectrum by drawing the structure of aspirin and labeling each H with the letter (A through C) to show which signal is produced by which H. 14 C B N 12 10 8 A 2 0 ppm FRYDE
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