[Trace63]

Bah, I have an extraction lab tomorrow and I'm confused. Basically before lab we have to right out a flow chart to how to extract Aspirin and Caffeine from a compound.

I did a TLC last lab of an unknown and found that it is a caffeine/aspirin. Caffeine is slightly basic and aspirin is acidic. How would I go about seperating the two. I know I have to add some ether to it at first to seperate one of the compounds and then "dry" it yata yata yata.

Any help?

[invisiblegs]

I recently taught a similar lab on the separation of organic acids and bases.  The first concept to think about here is solubility.  If you are going to dissolve your materials in ether, then I assume that you will extract one or both of them from the ether solution using a liquid/liquid extraction technique, and an aqueous solution.  Next, think about acid/base reactions, and their products.  What are the solubility characteristics of those reaction products?  It is also important to think about pKa values of your organic acid and base at this point.  You will want to react one of the species present in the mixture (ether layer), with an acidic or basic species in the aqueous layer.  The product(s) of that reaction will have different solubility characteristics, and should move from the ether layer to the water layer.  The last step would then be to convert your extracted product back to its original form.

[ARGOS++]

Dear Trace63,

Well spoken from InvisibleGS, - with simple words:
Dissolve the whole thing in Ether and extract one after the other as its salt by adjusting the pH of the aqueous Phase.  After “neutralisation” or reajusting the pH of each aqueous Phase you can isolate the “pure” Compounds.
This procedure is a small part of the so called “Organic Separation Procedure” for mixtures.

Good Luck!
                    ARGOS⁺⁺