Organic Chemistry Laboratory and Recitation I-Extraction of Caffeine from Tea Lab report 3 PDF

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Extraction of Caffeine from Tea Name: Course:

Organic Chemistry Laboratory and Recitation I

Instructor:

Dichloromethane

Calcium Chloride

Sodium Carbonate

Tea is one of the most commonly used caffeinated beverages in the world. Caffeine also causes an increase in respiration and heart rate, as well as nervousness and insomnia. Though caffeine has demonstrated to have physical dependence, it is also capable of improving alertness, learning capacity, and exercise performance [ CITATION Wil11 \l 1033 ]. Tea leaves contain tannins, which are acidic, as well as a number of colored compounds and a small amount of undecomposed chlorophyll (soluble in dichloromethane). To ensure that the acidic substances remain water soluble and that the caffeine will be present as the free base, sodium carbonate is added to the extraction medium [ CITATION Wil11 \l 1033 ].

Procedure: a) 15ml of distilled water was added into a 50 beaker, 2 grams of sodium carbonate, and a boiling stick was added to the beaker and placed in a hot plate to heat. b) Next a tea bag was added to the beaker and boiled for 5 minutes. During the evaporation of the water, the volume of the water was maintained at 15ml while adding water into beaker at the exact level. c) After heating for 5 minutes the solution beaker was removed from the hot plate and placed to cool, remaining liquid in the tea bag was poured into a large test tube (18x150mm). d) Then in another beaker the same tea bag was rinsed with 5 mL of hot water and poured into the test tube. e) After cooling occurred, while placed under the fume hood, 3mL of dichloromethane was added to the test tube solution which was gently shaken in order to avoid a sudden burst of chemicals outside the tube. f) Pasteur pipette was used to extract the dichloromethane layer seen at the bottom of the tube from the tea solution. The pipette was submerged all the way through the bottom of the tube while firmly holding the top rubber bulb of the pipette; as soon it reached the bottom, the rubber bulb was released and some of the dichloromethane layer was transferred at once through the pipette. The process was meticulously done in order to avoid collecting sample of tea from the top layer along with the dichloromethane. g) The process above was repeated three times until 2ml of dichloromethane layer was finally extracted and placed into a 25ml Erlenmeyer flask. Droplets of tea solution slip into the flask, despite of great precaution that was taken during the extraction of the dichloromethane layer.

h) So, calcium chloride pellets were added into the flask that contained the 2ml of dichloromethane in order to immediately dry off the tea sample droplets. Many pellets were added as needed until clear dichloromethane is displayed on top which indicated the solution finally dried. i) A vacuum flask was obtained and preweighted on the special scale of the laboratory. The initial weight indicated 40.531g; then the dichloromethane was added into it. The vacuum flask was weighed again which indicated 40.536g. j)

The vacuum flask was placed into the fume hood, then the sidearm of the flask was covered with a pipet bulb. Using the airline with a vacuum adaptor, the dichloromethane in the flask dried out until it formed a crude caffeine represented in a slightly visible white powered scattered all over the flask which wasn’t possible to be scraped to be weighted.

k) The vacuum flask that contained the dichloromethane powder was properly sealed with a small tube suspended within the flask; then the flask was placed into the sand bath to heat for 7 minutes until sublimation occurred. l)

the remaining caffeine that scattered all over the suspended tube wasn’t enough to be scrapped out over a weighing paper in order to be weighted accordingly. The instructor proposed to weight the actual tube with the scattered caffeine upon it using a weighing paper which resulted to 4.499mg of crude caffeine. then, the tube was rinsed and properly dried using the airline vacuum on the hood fume; it was placed on the scale for a final time using the same weighing paper which resulted a weight of 4.498mg. The final results for the mass of pure caffeine was calculated by subtracting 4.499mg of crude caffeine from the empty tube mass 4.498mg which comes out to 0.001mg.

Data:

Mass of empty vacuum: Mass of vacuum + dichloromethane: Mass of weighing paper and tube with

40.531g 40.536g 4.499mg

the extracted caffeine or Mass of Crude Caffeine: Mass of cleaned and Dried tube with

4.498mg

original weighing paper Mass of pure caffeine: % recovery = pure/crude x100%

0.001mg 0.022%

0.001mg/4.499mg x100 =

Conclusion: The objective of this experiment was to extract caffeine from tea. Based on the results of this experiment the mass of crude caffeine extracted was 4.499mg. A very weak extraction method by weighting the tube with the caffeine powdered scattered all over tube including the weighing paper which resulted with a crude mass of 4.499mg and 0.001mg the mass of the pure caffeine was calculated after subtracting the mass of the empty tube of 4.498mg. The method of extraction amongst other factors may have caused a lesser amount of caffeine to be extracted. Other factors may include inaccurately measuring or completing certain steps in the procedure. The sample size and method used play a major role in this outcome. The caffeine may not have completely dissolved in the dichloromethane, or maybe the solution was not given enough time too cool. The percent recovery of caffeine in this experiment was 0.022%. Sublimation was utilized to purify the extracted caffeine as much as possible. Therefore, the purpose of the experiment wasn’t a success because the caffeine wasn’t accurately extracted.

Reference: Williamson, K., & Masters, K. (2011). Macroscale and Microscale Organic Experiments. Belmont: Cengage Learning....