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Given that the final mass of acetaminophen crystals= 0.320g, – What is the percent recovery or…
Given that the final mass of acetaminophen crystals= 0.320g,
– What is the percent recovery or your product?
– If this is above 100%, propose reasons for this. If not, list possible sources for the loss lf product.
– What is the melting point (mp) of your product? The expected mp is 170C. What can you say about the purity of your product?
The weight of the acetaminophen tablet is 500mg as stated in step#15.
133 Experiment 11 Isolation of an Active Drug SAFETY NOTES Chemicals Used in This Experiment: • Acetaminophen Tablets Methanol, Highly Flammable! • Alumina, Neutral • Sand Acetone. Highly Flammable! Other Hazards: Thermal Mel-Temps Steam Baths INTRODUCTION Acetaminophen Figure 11.1) is one of the most common over-the-counter painkillers in the market. It is the active in- gredient in Tylenol, Excedrin, and other products, although it is not the only chemical present in these medicines. There are many inert substances present as well (for example, starch is commonly used to bind the ingredients so that they may be sold in tablet form). In this experiment, you will isolate acetaminophen from a commercially available painkiller, and will compare the NMR spectra of the powdered tablet to the NMR spectra acetaminophen. Why are there extra peaks in the NMR spectrum of Excedrin? CH Figure 11.1. Acetaminophen
134 Experiment 11 EXPERIMENTAL PROCEDURE 1. Use a mortar and prestle to crush one tablet completely to powder 2. Transfer the powder to a 5 ml conical vial; be sure to thoroughly scrape the residue from the 3. Add methanol to the 2 ml mark. 4. Cap the vial do not use an o-ring, mix with an automatic mixer for 1 minute, and set aside to let the solicis settle. 5. Set up a chromatography column as follows (analogous to the drying column you used previously a. Insert a piece of cotton inside a Pasteur pipette and camp it. b. Place your micro funnel in the Pasteur pipette. c. Add about 1/4 inch of sand in the Pasteur pipette. d. Add one inch of alumina in the Pasteur pipette. e. Add 1/4 inch of sand in the Pasteur pipette. 6. Place a 10 ml round bottom flask under a Pasteur pipette (as in Figure 11.2. D –Micro clamp Pasteur pipette 7. Add 2 ml methanol to the column and allow it to pass through until the level of methanol has dropped to the top of the sand (the sand on the top 8. Then, carefully transfer the supernatant liq- uid from your Tylenol-methanol mixture to the column using a Pasteur pipette (any solid transferred will clog the column and slow down the process). 9. Carefully, force the liquid from the column with a pipette bulb your instructor will demonstrate). Sand (1/8 inch) Alumina (1 inch) Sand (1/4 inch) – -Cotton Micro clamp 10. Use 1 mL of methanol to rinse the insoluble ingredients in the 5 mL conical vial and add the rinse to the column. 11. Once all of the liquid has been drained from the column, add a boiling chip to the 10 mL round bottom flask containing the acetamino- phen solution and distill all but I mL of the methanol by simple distillation. 12. Disassemble the distillation setup and re- move the boiling chip with a spatula; if no solid is present scratch the inside of your vial gently with a glass stirring rod to induce crystallization. 10 ml Pear-shaped flask Figure 11.2. Chromatography column
Isolation of an Active Drug 135 13. Collect your product by vacuum filtration Figure 4.1) and allow it to air dry for 5 minutes 1. Weigh your final product and determine its melting point. 15. Calculate your percent recovery based on 300 mg acetaminophen in a Tylenol tablet 16. Since you are working in pairs, one member of the pair should get the experimental setups prepared such as the chromatography column) ahead of times they are ready as needed LABORATORY SAFETY Although you are isolating a commercial drug your isolated product will not have passed appropri ate testing for purity and safety and should NOT be ingested. Methanol wood alcohol) is known to Cause blindness and other problems including death when ingested: handle with care and as always Keep your googles on. Use steam bath as the heat source to distill off methanol p. 65°C). NMR Spectra of Tylenol and Excedrin Tylenol in D20 Excedrin in D20
140 Experiment 11 2. Product a. (1 Point) What is the final mass of acetaminophen crystals that you have extracted? 0.320g b. (1 Point) What is the percent recovery of your product? c. (1 Point) If this is above 100%, propose reasons for this. If not, list possible sources for the loss of product. d. (2 Points) What is the melting point impl of your product? The expected mp is 170°C. What can you say about the purity of your product?
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