Experiment 3. Caffeine

During the extraction procedure, which layer (water/ ethyl acetate) is on top?

Ethyl acetate

Acetone is miscible with water. Would it be better or worse to use acetone (rather than ethyl acetate) for extraction of caffeine from water? Explain your answer.

It would be worse to use aceton since its miscible in water they will mix and wont form the serpate layers.

Which method(s) will you use to determine purity of the isolated caffeine?

Thin Layer Chromatography

A molecular formula for ethyl acetate is

C4H8O2.

molecular formula for caffeine?

C8H10N4O2

In Step 1 of the procedure, you are asked to measure Na2CO3. Why is the role of this compound?

-it extracts caffeine inro aqueous layrt

-extracts gallic acid into aqueous layer

In Step 2 of the procedure, which layer is organic in the separatory funnel?

top, Ethyl acetate

Predict what would happen with the Rf values of your isolated caffeine and pure caffeine samples, if instead of ethyl acetate you used hexanes as eluting solvent.

Both Rf values will decrease, due to hexanes being less polar solvent than ethyl acetate.

Caffeine is a member of a

alkaloids

the caffeine is first extracted into a

hot aqueous solution, which is made basic with

with sodium carbonate or sodium hydroxide.

caffine is more solbulbe in

non polar solvents like ethyl acetate

in TLC plate which componenet moves faster

less polar compound

why does more polar compunds move slower in TLC

due to hydrogen bonds and dipole dipole interactions

how to calcualte Rf

length from baseline to finial/ total baseline to top line

how much space is left on top and bottom of the silica gel TLC

1cm

caffeine strucutre

Na2CO3

anhydrous sodium

carbonate

solubility of caffeine in water is

22mg/mL at 25 C

what color do you want the limus to turn after placing the teabags in water

blue

blue lithmus =

basic solution