Caffeine lab Flashcards
What’s the goal of this lab?
Isolate caffeine
How are we isolating caffeine?
Fuck with the miscibility to make two layers, then fuck with the solubility to separate caffeine into its own layer
What are the two immiscible solvents other things go into?
Water and methylene chloride
What goes into methylene chloride?
The caffeine, it’s way more soluble in that
What goes into the water?
The things that aren’t caffeine
How do we get the non-caffeine things to be soluble in water?
Add sodium carbonate to suck up protons and make ions
What class of things are tannins in relation to this lab?
The things that go in water after sodium carbonate turns them into ions. They’re acidic.
Why methylene chloride?
It’s soluble with caffeine and not most other things, so you’ll be able to isolate mostly caffeine
What happens to methylene chloride when you separate it into its own solution? What’s left over?
It just evaporates. Crude caffeine is left over.
What do you do with crude caffeine after met chloride evaporates?
Purify it more so that it’s pure
How you purify crude caffeine?
Sublimation
General procedure?
1) make tea
2) Put it into 2 centrifuge tubes, dissolve solids in each w/ sodium carbonate
3) Add methylene chloride to grab the caffeine and centrifuge to separate
4) Put caffeine layer in flask. Do the whole thing more than once to get more caffeine
5) Figure out how much caffeine you got
What data do I need?
Percent recovery of caffeine
What kind of pipette do you use to move tea from 50ml beaker to centrifuge tubes?
glass
What do you need to add after you move tea into centrifuge tubes? How much?
Na2CO3 (.5g) to deionize (shake), DCM (3ml) to separate (shake)
