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I'm looking to do an extraction of caffeine from energy drinks. I want to use both sublimation and recrystallization in my experiment for advanced purity.

My question is which should happen first, recrystallization or sublimation? Does it even matter which happens first?

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  • $\begingroup$ You might want to break this question into 2 separate ones: one about sublimation and recrystallization; and another about solvents for extraction. As it stands, the query is rather broad and might be closed as such by the community. $\endgroup$ – Todd Minehardt Oct 24 '16 at 17:47
  • $\begingroup$ Why? This sort of inquiry makes me think that this is about some sort of quantitative analysis. Is that the case? $\endgroup$ – MaxW Oct 24 '16 at 19:18
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This sounds like a nice project.

For the purification of caffeine, sublimation in vacuum and recrystallization from ethanol are both conceivable.

But first you have to separate it from the other ingredients, such as carbohydrates.

According to the manufacturer, 100 mL of Red Bull, a popular brand, contain 11 g sugars and 32 mg caffeine.

In order to isolate the caffeine, two methods are possible:

  • extraction with $\ce{CH2Cl2}$
  • solid phase extraction on a C18 column

The latter method might be interesting. Imagine that your pour the energy drink through a preconditioned column of this adsorbent. The caffeine will be retained, whereas everything else passes through.

In a second step, you wash the caffeine off the adsorbent using ethyl acetate. Then, dry the organic solvent with sodium sulfate, filter off, evaporate the ethyl acetate, dry the crude material and check the melting point. If necessary, use any of the above two methods for purification.

If you'd like to read this in more detail, have a look at a procedure provided at Open BU, an open access initiative of the Boston University.


UPDATE

I'd probably use just one of the methods for purification, depending on the equipment available. But if you insist on using both, I'd recrystallize first.

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  • $\begingroup$ Hello, thank you so much for your reply I genuinely appreciate it. I fully intend to use Dichloromethane for the separation of caffeine intially from the rest of the products but since I have 40 hours of lab hours available I may also be able to take a look into the second methods. $\endgroup$ – Rida Oct 24 '16 at 18:45
  • $\begingroup$ My only issue is in terms of purification does it matter whether the recrystallization is done before the sublimation ? or vice versa? $\endgroup$ – Rida Oct 24 '16 at 18:46

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