Cou
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Separation of paracetamol, acetylsalicylic acid, and caffeine
Excedrin is an OTC drug, each tablet is made of active ingredients 250 mg aspirin, 250 mg paracetamol, 65 mg caffeine. What are some methods to
separate all 3 of these? I know that acetylsalicylic acid can be extracted quite easily with acetone as an organic solvent, but paracetamol and
caffeine also are soluble in acetone. But I've been told that acetylsalicylic acid also dissolves in water with a base dissolved in it.
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Mailinmypocket
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Try searching for "separation of excedrin" and lots of experimental procedures will come up, here is one example:
http://www2.volstate.edu/chem/2010/Labs/Extraction_lab%20fal...
[Edited on 3-4-2015 by Mailinmypocket]
Note to self: Tare the damned flask.
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mayko
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A basic aqueous solution would tend to deprotonate the lone-pair electrons on the nitrogen atoms of paracetamol (Fig.1) and caffeine (Fig.2),
rendering the molecule electrically neutral and soluble in organic solvents. Meanwhile, ASA (Fig.3) will have its carboxylic group deprotonated as
well, causing the molecule to take on a negative charge, and thus remaining highly soluble in water. This is the basic principle of an acid-base extraction. Check out, for example, Zubrick's Organic Chem Lab Survival Guide for a more in-depth discussion and general procedures.
This is assuming your goal is to extract ASA from the mix for fun and experience; isolating the amines might be trickier. And if you're looking for
lab-grade chemicals, save yourself the trouble and go for aspirin, tylenol, and food-grade caffeine off ebay
Fig. 1 Paracetamol (acetaminophen)
Fig. 2 Caffeine
Fig. 3 Acetylsalicylic acid
al-khemie is not a terrorist organization
"Chemicals, chemicals... I need chemicals!" - George Hayduke
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Amos
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I don't know what base mayko is suggesting above, but sodium carbonate and sodium hydroxide both react with paracetamol to form a water-soluble sodium
salt of the acid. This is the basis of making ibuprofenate salts.
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unionised
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Quote: Originally posted by Amos  | | sodium carbonate and sodium hydroxide both react with paracetamol to form a water-soluble sodium salt of the acid. This is the basis of making
ibuprofenate salts. |
How?
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Bert
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Thread Moved
3-4-2015 at 05:00 |
Metacelsus
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Paracetamol has a pKa of 9.38, whereas acetylsalicylic acid has a pKa of 3.49. You should be able to use sodium bicarbonate to deprotonate the
acetylsalicylic acid but not the paracetamol. From there, it's a simple extraction.
Also, Excedrin will also contain some insoluble binder.
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