Extraction of caffeine from tea

Question 1

What group of compound does caffeine belong to

Answer 1

Xanthines

Question 2

Layers of aqueous and organic

Answer 2

Top- aqueous
Down- organic

Question 3

What property explains why one layer is on top of the other?

Answer 3

Density

Question 4

Purpose of adding sodium carbonate

Answer 4

convert tannins to water-soluble salts; ensure that the acidic substitution remains water soluble and that the caffeine will be present as free-base.

Question 5

Too much drying agent is added to the extract, what is the overall effect on the final product?

Answer 5

May physically absorb all the liquids resulting to decreasing in the amount of product

Question 6

Assuming that you are not told which layer is the ethyl acetate and which is aqueous layer, how will you identify experimentally?

Answer 6

Add a few drops of ether, CHCl2 +H2O and observe which layer will be miscible

Question 7

Caffeine is soluble in methanol as well as in ethyl acetate. Why wouldn’t you use methanol to extract the caffeine from the aqueous portion?

Answer 7

It cannot be used to extract caffeine because methanol is miscible with water.

Question 8

What do some organic compounds used in caffeine extraction contain

Answer 8

Halogens like dichlorimethane

Question 9

Aside from ethyl acetate, what could be used to replace halogenated solvents for extraction procedure

Answer 9

ethyl acetate or supercritical CO2 or H2O in combination with organic solvents or water

Question 10

Which would be more soluble in in organic solvent, a charged molecule or neutral molecule

Answer 10

N in caffeine will form conjugate acid salts as a cation in an acidic condition. This increases its solubility in water.
It takes the neutral form when in basic condition. This increases its solubility in an organic solvent.