Caffeine Case
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Before the mixture was transferred in the separatory funnel, it was cooled down for about 3 minutes. After cooling, the mixture was transferred in the separatory funnel containing 20mL of dichloromethane. The separatory funnel was turned upside down and the stop cock was opened so to release the pressure inside. To mix, the solution was swirled and was turned upside down to release again the pressure inside. This procedure was repeated for two minutes. After mixing, the separatory funnel was placed in a steady position until the separation of the two layers is clearly visible.
While waiting for the mixture to settle down, using the triple beam balance, the evaporating dish was weighed and half spatula of anhydrous sodium sulfate was prepared and was put in the Erlenmeyer flask.
When the two layers were already evident, the lower layer or the organic layer was drained into the Erlenmeyer flask containing the prepared anhydrous sodium sulfate. The solution (sodium sulfate + DCM + caffeine) was decanted onto a pre-weighed evaporating dish. It was evaporated to dryness under the fume hood until the residue is completely in powder form and once again the evaporating dish together with the residue is weighed using the triple beam. Results were gathered and percentage yield was calculated.
Result and Discussion
Single Extraction was assigned to the group. Single and Multiple extraction is almost the same except that in multiple extraction, there is repeated extraction process. It is usually more efficient than single extraction because it allows more of the caffeine in the mixture to be extracted.
Notice in figure 4 that there are two layers the upper and the lower layer. The upper layer in the experiment, the less dense is the aqueous layer while the one in the lower layer, the denser, is called the organic layer. The organic layer constitutes of the dichloromethane and the caffeine extracted.
Fig.4 Extraction Set-Up
Caffeine can be extracted from tea leaves by boiling them in water yet, although caffeine is soluble with water, the caffeine will remain in the solution together with other compounds in particular, the tannins which can be eliminated by converting it to their salts (phenolic anions) by adding sodium carbonate
The purpose of the anhydrous sodium sulfate on the other hand serves as a drying agent that will remove any water that may be present before starting to evaporate the solvent off.
Data Gathered:
Weight of tea leaves used
10.00 grams
Weight of empty evaporating dish
103.30 grams
Weight of evaporating dish with extracted caffeine
103.70 grams
Weight of Caffeine
0.40 grams