Isolation of Caffeine From Tea
Isolation of Caffeine From Tea
Isolation of Caffeine From Tea
PURPOSE:
To expose the student to new equipment and lab procedures. And to determine the percent of caffeine in
a sample of tea leaves.
INTRODUCTION:
By selecting the proper solvent, specific compounds can be separated from solutions. Caffeine is a
natural compound in tea along with tannin, cellulose, chlorophyll and smaller amounts of other
substances. If raw tea is placed in hot water, caffeine and tannin will dissolve into the heated water
leaving cellulose and other substances as insoluble solids. If sodium carbonate is added to the heated
solution (of water, caffeine and tannin) the tannin reacts with the sodium carbonate and forms an
insoluble salt thus removing it from the solution. If the solution of water and caffeine is mixed with the
solvent dichloromethane, the caffeine is transferred to the dichloromethane. This results from the fact that
caffeine is much more soluble in dichloromethane than water. Water and dichloromethane are not soluble
in each other. The volatile dichloromethane can easily be vaporized off from the dichloromethane/caffeine
solution leaving fairly pure solid caffeine.
In this lab you will follow a rather complex set of procedures that separate caffeine from tea leaves.
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