SINGLE EXTRACTION OF CAFFEINE FROM TEA LEAVES
Anne Jillian M. Castillo
In this experiment, the technique used to separate an organic compound from a mixture of compounds is called Extraction. Extraction process selectively dissolves one or more of the mixture compounds into an appropriate solvent . Tea leaves were boiled in distilled water with anhydrous sodium carbonate in order to precipitate the tannins. The tea extract was then placed into a separatory funnel with dichloromethane because caffeine is more soluble in dichloromethane than water and also dichloromethane is immiscible with water; by doing so the caffeine was separated to the aqueous solution. The dichloromethane layer containing the caffeine was then drained into an Erlenmeyer flask with sodium sulfate in order to absorb all the remaining water in the solution. The extract was then decanted to the evaporating dish and was evaporated to dryness. The residue collected was the caffeine extracted from the tea leaves. Most of the teas available in the market contain 3-4% of caffeine.
The objective of this experiment is to extract caffeine from tea leaves using single and multiple extractions and to calculate the percentage yield of caffeine from both extraction procedures.
Caffeine is a very common substance and is found in coffee, tea, soft drinks, chocolate, and "stay-awake" pills such as Vivarin. It can be synthesized or isolated from natural sources. Caffeine constitutes approximately 4% of tea and coffee leaves, and is also found in cola nuts and cacao beans. In Humans, Caffeine acts to stimulate the heart, central nervous system, and the respiratory system. Blood pressure is increased by its use, since heart rate is increased, as is contraction force and volume output. It is a diuretic and has the effect of delaying fatigue. Caffeine has a bitter taste but no smell. There is research linking high Caffeine consumption in pregnant women to the malformation of their children. Caffeine is addictive to Humans. Regular consumption of drinks and food containing the drug reduce sensitivity to its effects, causing the body to become over-sensitive to adenosine. This causes a decrease in blood pressure, severe headaches, dizziness and tiredness. People have been known to die after ingesting large quantities of Caffeine, but it would take approximately 100 cups of coffee to reach these levels.  Caffeine is an alkaloid, and, more specifically, a member of the methylxanthines. Thus, Caffeine is closely related to theophylline and
theobromine. Pure Caffeine takes the form of white, hexagonal crystals, which can be broken into a soft powder. It has a melting point of 235 oC - 238 oC, and a molecular weight of 194.19 g/mol. It is easily soluble in Chloroform and partially soluble in water. Caffeine has the chemical name "3,7-dihydro- 1,3,7-trimethyl- 1H-purine- 2,6-dione" and the molecular formula C8H10N4O2. The image of Caffeine below shows oxygen atoms in red, Nitrogen atoms in blue, Carbon in gray, and hydrogen in white. [pic]
Fig. 1 Structure of caffeine 
The isolation of Caffeine from tea is a simple-seeming experiment, which in fact makes use of a number of rather advanced chemical processes. To isolate the Caffeine in a sample of tea, it is necessary to chemically separate the Caffeine from the rest of the tea prior to evaporation. This process is known as ‘extraction.’ Extraction is a chemical method of separating a specific component of a solution from the rest of the solution. This is done by using a solvent (in this case Dichloromethane) in which the substance to be isolated is very soluble, while the rest of the solution is not as soluble. EXPERIMENTAL
A. Sample Used
1. Tea leaves
Single extraction was used to extract caffeine from tea leaves.
1. 4.4 g of anhydrous sodium carbonate was placed in a small Erlenmeyer flask containing 100 ml of...
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