Guizin239
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Acid/Base extraction of ASA from aspirin
So, folks, I want to get myself some acetylsalicylic acid from some pills.
They contain 500mg of ASA, along with cellulose, talc and calcium phosphate.
I wanna know if it is feasible to react the ASA with sodium bicarbonate to make the sodium salt of aspirin, and then simply filter the solution to get
rid of the fillers. Then react the filtrate with a strong acid to get ASA back. Would that work? Is there anything I should be aware of?
The extractions I've seen on Youtube usually involve acetone or isopropanol.
I wonder why that would be the case, since this method I described here seems to be a bit cheaper.
What am I missing?
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DraconicAcid
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If you add a strong acid, you risk hydrolysing the ASA to acetic acid and salicylic acid.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Guizin239
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Welp, I was going for that anyways.
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DraconicAcid
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Then it should work fine.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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aga
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Oh, i am so glad that you will soon be telling us how your experiment went, with photos, calculations and yield.
Do you think it will take a long time ?
I'm very eager to see how your experiment goes, especially the photos.
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UC235
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Adding water to pills designed to expand and crumble in water will make a big mess and lots of glop. Using acetone to extract the ASA will avoid this.
Buy uncoated, extra strength tablets with minimal fillers aside from modified starch, crush, and extract with warm acetone. Filter off the unexpanded
starch then allow the acetone to evaporate.
For hydrolysis to salicylic acid, I recommend the one-pot hydrolysis/crystallization outlined in my prep of phenol which can be found in the
Prepublication subforum.
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nezza
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Dissolve aspirin in NaOH -> Sodium acetylsalicylate. Do not heat. Sodium Carbonate might work.
Filter out insoluble materials.
Add acid in the cold to precipitate out acetylsalicylic acid.
Heating the solution will hydrolyse the aspirin.
If you're not part of the solution, you're part of the precipitate.
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CharlieA
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A much "gentler" way to isolate ASA from aspirin is to wash the aspirin in cold water to remove soluble impurities, and then filter off the crude
ASA. After drying the ASA, it can be recrystallized from ethyl alcohol. Reference: Supplement to Robert Bruce Thompson's "Illustrated Guide to Home
Chemistry Experiments".
My recovery after 1 recrystallization was 72%; mp 133-4*C (lit. 135*C).
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