Tea Caffeine Extraction - Reading between the leaves

Part of a science and health package for Medill Reports here: (http://news.medill.northwestern.edu/chicago/news.aspx?id=122437).

In this video: Dani Friedland, Tara Kerpelman

Category:

Science & Technology

Tags:

• Tara Kerpelman
• tea
• caffeine
• extraction
• chemistry
• Dani Friedland

[GlenGeetar]

could you possibly please tell me how much tea solution you had at the start? and how much sodium carbonate was added? and how much solvent? it would be much appreciated as I am trying to replicate this experiment. thank you : )

[TaraInYourEyes]

Hi! I'm sorry but I do not know. I would suggest contacting Shelby Hatch at Northwestern - she was the one who helped us with this experiment.

Thanks for your interest! I hope it was useful to you.

[askar4kill]

gosh this was quick & V precise

[dnanalahcnap]

CH2CL2 is a potential carcinogen! You should not just evaporate it on a hotplate. At least use a fume hood. Safest thing to do is to distill it back :)

[Malangen7]

@jammmon bases are most certainly water soluble. The alkaline hydroxides are extremely soluble in water. The sodium carbonate maximizes the solubility differences between caffeine and the undesirables in the aqueous phase, which drives the caffeine into the methylene chloride layer. Otherwise the caffeine would have a tendency to remain in the aqueous phase because it can act as a Lewis base and there are other acidic compounds initially extracted with it.

[jammmon]

You add sodium carbonate to the tea to make it more water soluble? what the fuck? thats wrong. acids are soluble in water not bases xD

[Augis02]

Is this method suitable for coffe?

[siapajoyahyus]

We did this last week, and some procedures are different. the principles are the same, however. But thanks for this, I know what to write for my discussion in the final report. And I agree with localbroadcast bout the sodium carbonate, it's not for solubilty in water but in non polar solvents.

[localbroadcast]

ya got a couple things wrong... at the beginning, the purpose of adding sodium carbonate is not to make things more soluble in water.. it is to raise the PH of the water, converting the caffiene to the freebase form. In freebase form the caffiene is not soluble in water anymore, but is soluble in non polar solvents. That is why methylene chloride is added. Also.. they are not filtering water, they are filtering the methylene chloride.

[Pre2o]

Did you decant the methylene chloride with the sodium sulfate and had the crystals left over?? Thank you... Ver helpful

[MsGrammarnazi]

Thanks so much. It is so helpful to watch these things BEFORE going to lab!

[dah9vandals]

very cool