A well known insect has extracted cocaine many times and put together the following tips for other creatures that would like to experience pure cocaine, which is the only way it should be consumed in this insect's opinion.
1. The leaves extract much better when they are left in a humid area for a little while after the carbonate solution has been worked into them. It’s also good to leave them in a humid area before working in the solution.
2. Many times apliphatic carboxylic acids precipitates out of solution as the dilute sulfuric acid is being dripped in. This appears as an off-white powder and when this occurs a thick emulsion normally forms also so letting it sit longer than 30 minutes is necessary in this case. After the emulsion gets a little thinner pour off most of the non-polar and filter it. Then it can be placed into a sep funnel and the aqueous layer can be separated and filtered again. There is normally some crap floating around in the funnel that the non-polar layer likes to take up and after a few shakes it will all end up there. It takes a long time to gravity filter the emulsion and using a vacuum makes most of it pass right through the filter paper. If you let the aqueous layer sit for a day or so after you filter it again whatever small amount of emulsion/precipitate that should pass through will stick to the glass making it easy to decant leaving you with very clean aqueous fluid.
3. Washing the freebase off with a little water to remove the salts that also form is a good idea, but make sure the freebase is completely dry before adding it to the non-polar for precipitation of the HCl. If it’s not completely dry most of it will just stick to the bottom of the beaker. After water washing and letting it dry you can further purify it by adding it to some non-polar and decanting it from what clings to the glass (as there will almost always be some crap that doesn't dissolve in the non-polar no matter how dry the freebase is) and let it evaporate (no heat) as Myhero does.
4. It normally takes a while for the HCl to precipitate so don’t be alarmed if it doesn’t happen right away. It can take several hours up to a couple days for the cocaine to fully precipitate. Sometimes with smaller extractions it doesn’t precipitate at all even with some vigorous stirring so in this case you can let it evaporate (no heat!) and then scrape up the crystals… this won’t give the prettiest crystals, but that’s ok… you’ll have some pure powder and that’s all that matters.
And a few pics...
http://img157.imageshack.us/my.php?image=untitled23vh.jpg
Freshly precipitated crude base, which is still very wet. This is from 1Kg.
http://img490.imageshack.us/my.php?image=untitled133fl.jpg
As the HCl/acetone was being dripped in a small amount spilled onto the filter paper that still had a little base on it and after a few minutes beautiful crystals started popping up. They looked like little trees covered in snow. This insect wishes they had some type of magnification device... this picture hardly does it justice.
http://img51.imageshack.us/my.php?image=untitled9hu.jpg
Including what's on the mirror that's a little over 1.5gm... the insect got roughly the same amount from the other crystallization dish. There was also a very small amount of colorless prism-like crystals, which where more than likely p-xylene since the evaporation was done by an open window and it was cold outside that night, but of course this was washed away in the solvent washes.
Also, check these out...
1)
http://www.youtube.com/watch?v=lZHUmyrwOXI
2)
http://www.youtube.com/watch?v=jbuNCoXpOGE