Experiment #3: Isolation of Caffeine from Tea Leaves
The purpose of this lab was to extract caffeine from tea leaves, crystallize it and determine whether or not our findings were actually caffeine by using a melting point determination. Introduction:
Caffeine is a member of compounds organic chemists call alkaloids. Alkaloids are organic compounds containing nitrogen. Caffeine can found in many things can act as both a stimulant and diuretic. The way we will observe our caffeine will come from a sample of tea. To obtain the caffeine, we were introduced to 4 different methods. These methods include: a) Extraction, b) sublimation, c) crystallization, and d) decantation. The methods we used include extraction and crystallization. In extraction, we created two different layers, one aqueous and one organic. To make the two layers, we added dichloromethane. After decanting, we placed the sample under the hood to crystallize.
To a 200-400 mL flask, add 1 large (3 small bags) tea bag and 10 g of sodium carbonate.
In a separate beaker, boil 150 mL of water, then add to the flask containing the tea bags. Let this stand for 6-8 minutes, and then pour the liquid part into another flask. To the flask containing the tea bags, add another 30 mL of hot water and immediately add this to the first extract.
Press the tea bag to expel as much liquid as possible without breaking the bag. Add this to the extract also. Cool extract to room temp and discard the tea bags.
Transfer the tea extract from the flask to a 125 mL separatory funnel supported by a ring on a ring stand.
Add 20 mL to the funnel. Stopper the funnel and grab the neck of the funnel with one hand and the stopcock with the other in a way that you can turn the plug in the barrel to open and close the stopcock. While holding the stopper tightly, invert the funnel so that the liquid is no longer in contact with the stopcock. Pointing the stem of the funnel away from...
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