SIMPLE EXTRACTION OF CAFFEINE FROM TEA
Jeff Daniel S. Mendoza, Emmanuelle F. Nazareno , Patrick Denzel N. Pomer, Mae Therese A. Portugal, Ma. Erin D. Ramos Group 7 2C Pharmacy Organic Chemistry Laboratory ABSTRACT This experiment was performed so we can be able to differentiate single from multiple extraction and able to calculate and compare their results. Before performing the experiment, we discussed briefly the principle of extraction and the procedures of the said experiment. After the pre-laboratory discussion, we discussed among ourselves in the group and observed division of labor for faster facilitation of experiment and ensure that each task will be performed efficiently and accurately. We started by preparing the anhydrous sodium carbonate solution wherein tea bags are immersed together with it inside the beaker and allowed to boiled. While waiting for the tea bags, we assembled the separatory funnel set-up and prepared the dichloromethane solution. We were asked to perform the single extraction so after getting the boiled tea, we extracted the boiled solution using dichloromethane in the separatory funnel until a visible separation of two layers were observed. We drained the organic layer containing caffeine and transferred it to a clean Erlenmeyer flask containing anhydrous sodium sulfate. Then the solution was decant in the tared evaporating dish, evaporated to dryness under the hood, weighed the residue and percentage yield of the residue was calculated and obtained.
INTRODUCTION Extraction is a common technique used in organic chemistry to separate or isolate a desired compound from a mixture. Extraction process selectively dissolves one or more of the mixture compounds into an appropriate solvent. That’s why in this method, a solution is mixed thoroughly with a second solvent that is immiscible with the first solvent. The solution of these dissolved compounds is referred as the Extract . The two major types of extractions used in the organic laboratory are solid-liquid extraction and liquid-liquid extraction. Solid-liquid extraction is often used to isolate a natural product from its biological source, such as the leaves or bark of a tree. For example, the anti-cancer drug paclitaxel (Taxol®) can be isolated from the bark of the Pacific yew tree by solid-liquid extraction with methanol. Liquid-liquid extraction is the most common extraction technique, and involves partitioning a solute between two immiscible liquid phases, usually an aqueous phase and an organic solvent phase. In this case, we particularly used the liquid-liquid extraction also known as solvent extraction and partitioning. There are another two types of extraction, single extraction and
multiple extractions. Single extraction introduced dichloromethane to the tea solution only once,
while multiple extractions introduced dichloromethane to the solution three times. The objective of this experiment is to compare single and multiple extractions of caffeine, calculate the percentage yield of caffeine for extraction procedure and primarily separate caffeine from the black tea. Caffeine (Fig.1) is an alkaloid (a class of naturally occurring compounds containing nitrogen and exhibiting the properties of an alkali, hence the term alkaloid ) which is found in many sources, such as tea and coffee. In fact, the amount of caffeine in tea leaves can be as much as 5%. It is one of the methylxanthine compound has long been that known to be a natural ingredient present in coffee, tea and cola. It is highly lipophilic compound that can elevate mood; decrease fatigue, release tension, relax smooth muscle, bronchial muscle, stimulate CNS and cardiac muscle and also acts a diuretic (Mukhopadhyay (Mukhopadhyay et al, 2003)
O H3C
N
N
O
CH3
N
N
CH3 Figure 1: Caffeine structural formula
EXPERIMENTAL A. Compounds tested (or Samples used)
Figure 2: Separatory Funnel After 10 minutes, the mixture boiled then we squeezed the liquid inside the tea bag by pressing it against the side of beaker using a stirring rod and removed the tea bags. Before transferring the mixture in the separatory funnel, it was cooled for about 3 minutes. When the mixture was cooled, it was transferred to the separatory funnel together with the dichloromethane. The solution were shake inside the funnel and the funnel was carefully inverted to open the stop cock to release built-up pressure inside (Fig. 3). This was done for about 5 minutes then let it stand for 2 minutes or until the separation between two layers is clearly visible.
No. 1 National Black tea
B. Procedure The experiment required a bunsen burner, separatory funnel, Erlenmeyer flask, glass rod, evaporating dish, iron stand, iron ring, iron clamp, tea bags containing black tea, sodium carbonate (Na2CO3), dichloromethane (CH2Cl2) and sodium sulfate (Na2SO4). Single extraction was assigned to the group. First, 4.4 g of anhydrous sodium carbonate was placed in a small Erlenmeyer flask and added 100 mL of distilled water which we heated in a water bath until the sodium carbonate dissolves. Then 10 g of tea leaves contained in the tea bag to the mixture were added which was covered and boiled for 10 minutes. While waiting for the mixture to boil, we prepared the separatory funnel set-up (Fig.2) and dichloromethane.
Figure 3: Correct method for venting the separatory funnel
When two layers are already visible, the lower layer or organic layer was drained in a clean Erlenmeyer flask and discarded the upper layer or aqueous layer which is known to be the decaffeinated tea. Then a halfspatula of anhydrous sodium sulfate was added to the obtained organic layer, decanted it in a tared evaporating dish and evaporated it to dryness under the hood.
RESULTS AND DISCUSSION Our group performed one type of extraction called single extraction. Single and multiple extraction are almost the same except that in multiple extraction, there is a repeated process of extraction. Obviously, it is more efficient than the single extraction since repeated process of extraction obtains more of the caffeine. In the experiment, there are two layers observed in the separatory funnel; the upper and the lower layer (Fig. 4). The less dense upper layer in the experiment is the aqueous layer while the one in the denser lower layer is called the organic layer. The organic layer constitutes of the dichloromethane and the caffeine extracted while the aqueous layer consist of decaffeinated tea.
agent in the sample so we can be able to get 100% of the extract which is the caffeine. After evaporating the solution into dryness under the fume hood, the following are observed to the residue: it has yellowish white color wherein the yellowish part can be explained by the presence of chlorophyll, since tea came from a plant leaves of Camellia sinensis. It has amorphous powder appearance and tea-like odor which is soluble in water and dichloromethane.
Data gathered:
a. Weight of tea leaves used
10 g
b. Weight of evaporating dish + caffeine
115.12 g
c. Weight of empty evaporating dish
113 g
d. Weight of caffeine
2.12 g
Computations:
% of caffeine =
weight of crude
X 100%
weight of tea leaves
= 2.12 g 10 g Figure 4: Two layers observed in the funnel
Caffeine are already obtained in the boiling water, though it is together with other compounds particularly the tannin. Sodium carbonate as added so that these tannins are converted into their salts and can be eliminated from the solution. Anhydrous sodium sulfate, on the other hand, serves as absorbent of water or drying
X 100%
= 21.2 % crude A percentage yield of 21.2 % is obtained after computing for the ratio of weight of crude and weight of tea leaves used multiplied by 100%. Therefore, in every 10g of tea leaves contain 2.12 g of caffeine.
REFERENCES: From books: Barbaro, J., Hill, R. (2005). Experiments in Organic Chemistry. 3rd ed. Raleigh, NC: Contemporary Publishing Company Engel, R.G., Kriz, G.S., Lampman, G.M., Pavia, D.L. (1999 ). Introduction to Organic Laboratory Techniques . 5th ed. Belmont CA, U.S.A.: Brooks/Cole Cengage Learning Bathan, G.I., Bayquen, A.V., Cruz, C.T., Crisostomo, A.B., De Guia, R.M., Farrow, F.L., Peña, G.T., Sarile, A.S., Torres, P.C. (2009). Laboratory Manual in Organic Chemistry. Quezon City: C&E Publishing Inc. Forbes, D.C., Mayo, D.W., Pike, R.M.(1999). Microscale Organic Laboratory . 5th ed. New York, U.S.A.: John Wiley & Sons Inc. From the internet (on-line): Gutierrez, H.G. Extraction http://www.scribd.com/doc/35716872/Extrac tion-of-Caffeine-from-Tea-Leaves 9/03/14 From Scientific Journals: Ali, M., Sharma, P.K., Yadav, D.K., Physicochemical and Phytochemical evaluation of different black tea brands. Journal of Applied Pharmaceutical Science 01 (03); 2011: 121-124