Questions: 1. Explain each step in the purification process of the (+)-Ibuprofen from the racemic mixture....

Transcribed Image Text:

Questions: 1. Explain each step in the purification process of the (+)-Ibuprofen from the racemic mixture. 2. Can you predict the sign of (R)-limonene? Explain. 3. Give a detailed reaction mechanism for each chemical reaction in this experiment. 4. What would happen if you attempted to separate a racemic mixture of (+)-Ibuprofen with a mixture of (+)- aα-methylbenzylamine? Would it be possible to perform the resolution of (+)-Ibuprofen with (+)- a-methylbenzylamine? Explain. 5. Cool the solution to room temperature then place in an ice-water bath for a few minutes. Vacuum filter the solution and wash the solid with a few milliliters of ice cold water. 501nL 6. Transfer the solid to a beaker and add a 5 mL of 2-propanol. Heat this mixture using a steam bath to dissolve the solid. If necessary, continue adding 2-propanol until the salt crystals are dissolved. Set the beaker on the bench top to cool to room temperature then place in an ice water bath. 999m². 7. Vacuum filter the salt. Transfer the solid to a beaker and add 10 mL of 2 M H₂SO4. Stir until all the solid is dissolved. 8. Transfer this solution to a separatory funnel and extract the aqueous layer with 10 mL methyl t-butyl ether (MTBE). Repeat this extraction 2 more times and combine the three organic layers. 9.95ml 9. Wash the organic layers with 10 ml of water followed by 10 mL of saturated NaCl solution. 3.059 +1.699. 10. In a beaker, dry organic layer with 3 g of anhydrous sodium sulfate for 5 minutes. If the sodium sulfate clumps, add more anhydrous sodium sulfate to the organic layer and dry for an additional 5 minutes. 11. To remove MTBE, set up a simple distillation and heat using the steam. Stop the distillation when there is no more MTBE being collected or the temperature at the still head is higher than 60 °C. Discard the solvent in the receiving flask and transfer the resolved ibuprofen from the distilling flask to a beaker. 12. Set aside the resolved Ibuprofen as it usually solidifies upon standing. If necessary, scratch the inside of the beaker with a glass rod to promote solidification. If it does not solidify, place the beaker in an ice water bath and scratch with the glass rod. ad (+)-Ibuprofen Introduction: Please refer to Reference 1 for further details. This reference is available on D2L under the "Contents" tab. Procedure: Part A: Resolution of (+)-Ibuprofen 1. Mount a 3-neck adapter, a dropping funnel and a reflux condenser to a R.B. flask as shown on Figure 5.1. Figure 5.1: Reflux Apparatus for the Resolution of (+) Ibuprofen -Dropping Funnel 3-Neck Adaptor 2. Add 3.0 g of (+) Ibuprofen, 30 mL of 0.25 M KOH and a few boiling chips to a 100 mL round bottom flask. 3. Add 1.0 mL of S-(-)- a-methylbenzylamine to the dropping funnel. 4. Heat to dissolve the ibuprofen then cool the solution slightly before adding the amine dropwise. Once the amine is added to the reaction mixture, continue heating to reflux for 15 minutes with gentle heat. Questions: 1. Explain each step in the purification process of the (+)-Ibuprofen from the racemic mixture. 2. Can you predict the sign of (R)-limonene? Explain. 3. Give a detailed reaction mechanism for each chemical reaction in this experiment. 4. What would happen if you attempted to separate a racemic mixture of (+)-Ibuprofen with a mixture of (+)- aα-methylbenzylamine? Would it be possible to perform the resolution of (+)-Ibuprofen with (+)- a-methylbenzylamine? Explain. 5. Cool the solution to room temperature then place in an ice-water bath for a few minutes. Vacuum filter the solution and wash the solid with a few milliliters of ice cold water. 501nL 6. Transfer the solid to a beaker and add a 5 mL of 2-propanol. Heat this mixture using a steam bath to dissolve the solid. If necessary, continue adding 2-propanol until the salt crystals are dissolved. Set the beaker on the bench top to cool to room temperature then place in an ice water bath. 999m². 7. Vacuum filter the salt. Transfer the solid to a beaker and add 10 mL of 2 M H₂SO4. Stir until all the solid is dissolved. 8. Transfer this solution to a separatory funnel and extract the aqueous layer with 10 mL methyl t-butyl ether (MTBE). Repeat this extraction 2 more times and combine the three organic layers. 9.95ml 9. Wash the organic layers with 10 ml of water followed by 10 mL of saturated NaCl solution. 3.059 +1.699. 10. In a beaker, dry organic layer with 3 g of anhydrous sodium sulfate for 5 minutes. If the sodium sulfate clumps, add more anhydrous sodium sulfate to the organic layer and dry for an additional 5 minutes. 11. To remove MTBE, set up a simple distillation and heat using the steam. Stop the distillation when there is no more MTBE being collected or the temperature at the still head is higher than 60 °C. Discard the solvent in the receiving flask and transfer the resolved ibuprofen from the distilling flask to a beaker. 12. Set aside the resolved Ibuprofen as it usually solidifies upon standing. If necessary, scratch the inside of the beaker with a glass rod to promote solidification. If it does not solidify, place the beaker in an ice water bath and scratch with the glass rod. ad (+)-Ibuprofen Introduction: Please refer to Reference 1 for further details. This reference is available on D2L under the "Contents" tab. Procedure: Part A: Resolution of (+)-Ibuprofen 1. Mount a 3-neck adapter, a dropping funnel and a reflux condenser to a R.B. flask as shown on Figure 5.1. Figure 5.1: Reflux Apparatus for the Resolution of (+) Ibuprofen -Dropping Funnel 3-Neck Adaptor 2. Add 3.0 g of (+) Ibuprofen, 30 mL of 0.25 M KOH and a few boiling chips to a 100 mL round bottom flask. 3. Add 1.0 mL of S-(-)- a-methylbenzylamine to the dropping funnel. 4. Heat to dissolve the ibuprofen then cool the solution slightly before adding the amine dropwise. Once the amine is added to the reaction mixture, continue heating to reflux for 15 minutes with gentle heat.