Extraction of Caffeine

[Aatin D]

I want to extract some caffeine from coffee. Is it plausible, and if so, how is it done?

 

Thanks in advance!

[Suxamethonium]

It's done all the time to produce decaffeinated coffee. I think they use supercritical carbon dioxide these days or they can use water- but they used to use DCM (which is available in most labs and can be special ordered by most schools if they don't usually stock it).

 

Other solvents to try are ethyl acetate (safer), or the more hazardous benzenes (alkyl benzenes, or benzene) or tetrachloroethane.

[hypervalent_iodine]

DCM is a good system to use, as noted by Suxamethonium. There was actually a question about this here not long ago (IIRC), I'll see if I can find it.

 

Edit: http://www.sciencefo...eine-synthesis/

 

The easiest way to do it is just to extract it from instant coffee. I used to tutor a first year prac where students did exactly that. They dissolved about 10 grams in water and did a liquid-liquid extraction with DCM, dried over MgSO₄ and would get about 1gm or so of crude caffeine. Recrystallisation with minimal hot ethanol returned about 0.1 - 0.2 gm pure caffeine for most. A more skilled hand would do a bit better, but it's not really that bad and it certainly is an easy way to do it.

[Aatin D]

Instead of DCM, or Ethyl acetate, can I use another organic solvent, like ethanol?

[hypervalent_iodine]

Not if you want it to be pure. Ethanol is miscible in water, so you won't be able to wash out the other compounds.

 

Edit: And caffeine is not incredibly soluble in room temperature ethanol, so you'd be limiting your yield.

[CharonY]

If you are lazy and have access, solid phase extraction columns with C18 can also be used. Or pack them yourself (though arguably doing LLE is easier at that point).

[Suxamethonium]

If you are doing this at home you may be able to use DCM from paint-stripper. In Australia we only seem to have the gel type readily available (which involves distilling before it can be used as a solvent- but it only needs a low temp so I use a water bath). Obviously this comes with its own hazards, and the impurities in the DCM in paint-stripper will likely contaminate your product (which may or may not be an issue depending on your application).

[Aatin D]

Judging by this, the best way to go would probably be Ethyl Acetate. Are there any common sources of Ethyl Acetate?

[liambob1]

Judging by this, the best way to go would probably be Ethyl Acetate. Are there any common sources of Ethyl Acetate?

 

Its the Ester of Ethanol and acetic acid

CH₃CH₂OH + CH₃COOH ⇌ CH₃COOCH₂CH₃ + H₂O

You can also find it in decent quantity in non-acetone nail varnish remover <br class="Apple-interchange-newline">

Edited July 21, 2012 by liambob1

[Suxamethonium]

Try buying ethyl acetate as a solvent first, as the nail polish remover has a number of co-solvents (propylene glycol, etc) and contaminants (dyes, fragrances, preservatives) that will probably interfere with your extraction.

[Aatin D]

Does anyone have a specific experiment procedure that explains the science too?

[hypervalent_iodine]

Can I ask what you need this for? It will help us to help you better if we know.

[Aatin D]

There isn't a very specific reason. But I can say I dont want to use the caffeine as a supplement. I want to try this as an experiment is all.

[adianadiadi]

It is possible to extract caffeine from tea powder using carbon tetrachloride. In fact tea powder has more caffeine than coffee beans. As far as I remember, the extraction goes smoothly. Final crystallization with charcoal will give the pure crystals.

 

I want to extract some caffeine from coffee. Is it plausible, and if so, how is it done?

 

Thanks in advance!

[Suxamethonium]

Except that carbon tet is pretty nasty and harder to get these days. Can use Chloroform or DCM instead though as mentioned before.

[hypervalent_iodine]

Yeah, there's no way our friend is getting carbon tet. DCM is much simpler to obtain. And recryst with ethanol works just fine.