INORGANIC AND ORGANIC CHEMISTRY LABORATORY REPORT Subject Lecturer Instructor Faculty/Class Date of Experiment Date of Lab. Report Semester Time of Experiment
: Inorganic and Organic Chemistry Laboratory : Dr. rer. nat. Filiana Santoso, Mr. Hery Susanto M.Si : Mr. Tabligh Permana, Mr.Hery Sutanto M.Si, Ms. Sylvia Yusri, S.Si : Life Science/LS 2A : 6 May 2014 : 13 May 2014 : 2 : 14.00 17.00 p.m –
Experiment:
Extraction of Caffeine from Tea
Name:
Kristania Hadhiwaluyo Chita Sakina Putrianti Elias Harmanto
Campus BSD City Bumi Serpong Damai Tangerang 15321 – Indonesia
Tel. Fax.
+62 21 537 6221 +62 21 537 6201
[email protected] www.sgu.ac.id
I.
Objectives
II.
To understand about the Extraction of Caffeine from Tea
Theoretical Background
Extraction is a method used for the separation of organic compound from a mixture of compound. This technique selectively dissolves one or more compounds into an appropriate solvent. The solution of these dissolved compounds is referred to as the extract. The process is extremely important in a wide range of technical applications, for instance biotechnology, the pharmaceutical and food industries as well as environmental protection. Extraction is a separating process which has the advantage of low energy consumption, high efficiency, high selectivity and less expensive alternative compared with competing separating methods such as distillation, evaporation and membrane technology.
This experiment will be conducted to extract caffeine sample from tea. Tea itself is a beverage that is commonly consumed by many people since 2,000 years ago in China, and infusing the young leaves basically produces it and leaf buds of the tea plant, Camelia Sinesis in the boiling water. In terms of its chemical composition, the chemical substances in tea can be divided into two major groups: water (moisture) (75-78% in fresh fleches) and dry matter (22-25% in fresh fleches). Inorganic matters constitute 3.5-7.0% and organic matters constitute 93-96.5%. However only 30-50% of all substances is water-soluble (extractive) and passes into tea infusion. In the case of this experiment, the organic compound caffeine will be focused on.
Caffeine is a chemical name, 1,3,7 - trimethylxanthine, belongs to a wide class of compounds known as alkaloids that is found in over 60 plant species. Caffeine is found in coffee (100 mg/cup), tea (30-75 mg/cup), chocolate (6-35 mg/oz), and cola (46 mg/12 oz). The caffeine itself is belong to a family of naturally occurring compounds known as xanthines which is considered as the oldest known stimulants. Additionally, this organic compound is considered as the most powerful xanthine in its ability to increase alertness, put off sleep, to increase ones capacity for thinking, relaxes the blood
vessels, and increases urination. Due to its structure, caffeine is both soluble in polar and nonpolar solvent. The solubility of caffeine in water is 22mg/ml at 25°C, 180mg/ml at 80°C, and 670mg/ml at 100°C. In this experiment, the organic solvent dichloromethane (CH2Cl2) is used to extract caffeine from aqueous extract of tea powder because caffeine is more soluble in dichloromethane (140mg/ml) than it is in water (22mg/ml). The dichloromethane and caffeine mixture can then be separated on the basis of the different densities of dichloromethane and water because dichloromethane is much denser than water and insoluble in it. Residual water is separated from dichloromethane by drain out the dichloromethane through separating funnel, thus dichloromethane passed through the funnel while polar solvents such as water is still remains in the funnel. But since, water and dichloromethane is slightly soluble in each other, so after separating the solvents, residual water will remain the organic layer.
However in the tealeaves, caffeine does not exist as the only organic compound. Instead, the tea leaves are mainly consist of cellulose, pigments, chlorophylls, and tannins. Tannin, also called Tannic Acid, is any of a group of pale-yellow to light-brown amorphous substances in the form of powder, flakes, or a spongy mass, widely distributed in plants and used chiefly in tanning leather, dyeing fabric, making ink, and in various medical applications. Tannin solutions are acid and have an astringent taste. This organic compound is responsible for the astringency, colour, and some of the flavour in tea. The presence of these other compounds finally may lead to the impurity of the caffeine after it has been extracted from the tea sample which may cause alteration in the method used in extracting the tea sample, which will be shown later in the report.
III.
Equipment and Materials
Equipment:
-
Round bottom flask, 100 cm 3, 1
-
Magnetic stirrer, 1
-
Hotplate
-
Cod water bath
-
Separation funnel, 100 cm3, 1
-
Distillation unit
-
Digital Balance
IV.
-
Glass rod, 1
-
Glass beaker, 100 cm3
-
Glass beaker, 250 cm3
-
Oven
-
Graduated cylinder, 50 cm3
-
Bulb
-
Graduated pipette, 25 cm3
Materials:
-
H2O(l), distilled water, 30 cm3
-
H2O(s), ice block
-
Tea Bag, 1
-
Sodium carbonate (Na2CO3), 2 g
-
Dichloromethane (CH2Cl2), 75 cm3
Procedures
1. The mass of the tea bag was measured in a digital balance, and the value that was obtained was recorded in the data table as follows Mass (g) Empty 100 cm3 round bottom flask + magnetic stirrer 100 cm3 round bottom flask + caffeine + magnetic stirrer Tea bag
2. The mass of an empty 100 cm3 round bottom flask and magnetic stirrer was measured and the data value was recorded in the data table.
3. The 100 cm3 glass beaker was filled with 30 cm3 H2O(l), distilled water 4. 2g of Sodium carbonate (Na2CO3), was measured and placed inside the 100 cm4 glass beaker
5. The tea bag was also placed inside the 100 cm4 glass beaker and then was heated while being stirred with a glass rod, on a hot plate with a temperature of 290 0C for 20 minutes
6. The mixture obtained in the 5th step was placed in a water bath containing ice block to cool its temperature until its temperature reached around 25 0C (the more or less similar value to the room temperature).
7. 25 cm3 Dichloromethane (CH2Cl2) was taken with bulb and graduated pipette and was placed inside a 50 cm3 graduated cylinder.
8. The cool tea extract was transferred into a separation funnel and 25 cm3 Dichloromethane (CH2Cl2) was added carefully into the solution by tilting the separation funnel.
9. The separation funnel was held horizontally with two hands, the stopper was held tightly with one hand (by inverting the funnel) and the cap of the separation funnel was also held tightly using another hand to make sure there was no liquid that would spilled.
10. The separation funnel was gently shaken up and down (counted as 1 shake) for 5 times. Built up pressure caused by gases accumulating inside was released by opening the stopper.
11. The 10th time was repeated if there were some gas bubbles containing CO2 that can be seen.
12. Two distinct layers were formed after a few minutes with the dichloromethane layer at the bottom.
13. The lower layer was carefully drained into another 100 cm3 beaker glass. Note: Procedures that might be done according to condition
-
In the case of this experiment, the seventh up to the thirteenth may be repeated for 2 or three times by reading the filtered lower layer back into the separation funnel and by adding another 25 cm3 Dichloromethane (CH2Cl2) until a clear solution form at the bottom layer was formed.
-
If an emulsion (cloudy) layer between two clear layers was formed, another 25 cm3 Dichloromethane (CH2Cl2) may be added into the separation funnel
14. Distillation unit was set according to the figure as shown below
15. The clear solution obtained from the separation funnel was poured into the empty, 100 cm3 round bottom flask that has already had a magnetic stirrer.
16. The 100 cm3 round bottom flask containing the solution was put into the distillation unit until the Dichloromethane (CH2Cl2) solvent was gone leaving the caffeine in the form of solid precipitate behind.
17. The 100 cm3 round bottom flask containing the sample were put into the oven to evaporate all water molecules that are also present within the distilled sample.
18. The mass of 100 cm3 round bottom flask containing thin crust (after being put inside the oven) and magnetic stirrer was measured and recorded in the data table.
V.
Observation (Data)
Table 1: Mass of different materials used in the experiment Mass (g) Empty 100 cm3 round bottom flask + magnetic stirrer
49.1246
100 cm3 round bottom flask + caffeine + magnetic stirrer
49.1598
Tea bag
1.79
Table 2: Observation on Changes that happen during the extraction process Process Heating (boiling the tea with water & sodium carbonate (Na2CO3))
Extraction using separation funnel
Changes The tea bag used in this experiment was boiled with water and sodium carbonate, after 5 to 10 minutes the color of the solution starts to change in to a brown color, which its intensity increases through time and odors could be smelled. After the solvent, dichloromethane was added into the solution two layers was formed, the bottom layer was dichloromethane that was contained of caffeine while the upper layer containing the other solution that was not soluble in dichloromethane. However when the 25 cm3 Dichloromethane (CH2Cl2) was firstly added into the solution, emulsion a cloudy layer between two clear layers was formed. Although the simplest way to get rid of the formed emulsion is by swirling the contents of the funnel or by stirring the contents using a glass rod another 25 cm3 Dichloromethane (CH2Cl2) was added.
White crust in the form of precipitate was formed and present in the bottom surface of the round bottom flask. This crust-like precipitate contains the caffeine (the targeted product), however it is seen in the figure below that the caffeine that should be white in color has a greenish color which indicates a presence of another organic substance, namely called tannin.
Distillation and End Result
VI.
Discussion Mass of Caffeine Mass of 100 cm3 round bottom flask, extracted caffeine, and magnetic stirrer - Mass of empty 100 cm3 round bottom flask and magnetic stirrer 49.1598 - 49.1246 = 0.0352 g ANALYSIS Obtaining pure organic sample from a mixture of various different compound inside a substance require the method that can separate that certain pure organic sample from the other components. The method that is used to separate an organic compound from a mixture of various kind of compound is called extraction. A good application of this method is the extraction of caffeine, which separates caffeine from the other substances found in tea leaves. Basically tea is the dried and prepared leaves of a shrub, Camellia sinensis , from which a somewhat bitter, aromatic beverage is prepared by infusion in hot water. This common yet nutritive beverage contains different kinds of substances that can be categorized into two major groups: water (moisture) (75-78% in fresh fleches) and dry matter (22-25% in fresh fleches). Inorganic matters constitute 3.5-7.0% and organic matters constitute 93-96.5%. However the composition that makes up the commercially
sold tea, found in the market only made up of 30-50% of all substances that is watersoluble (extractive).
In the case of this experiment, the substance that is going to be separate from the various different substances present in the tea is caffeine. Caffeine is a natural organic substance that is found inside the tea and it will be extracted by following the mechanism as follow:
The first step of the mechanism was solid-liquid extraction in which insoluble material (material inside the tea that is insoluble in water) or non-polar components are separated from the soluble material or polar components. This process was done by boiling the tea bag with water along with 2g of Sodium carbonate (Na2CO3). Firstly, the boiling process dissolved the caffeine in the tealeaves into the water so it would be separated from other insoluble substances such as cellulose, the primary leaf component. These insoluble substances were then become easily removed because it is virtually insoluble in water. Secondly the 2 g of the Sodium carbonate (Na2CO3) was also added in this boiling process, because if the boiled or brewed tea is directly inserted to the separation funnel with the add of the solvent, dichloromethane (CH2Cl2) other organic compounds such as tannins will also be extracted therefore by acting like a base that convert organic compounds such as tannins into their sodium salts so during the extraction process using the separation funnel they will be substances which are not soluble in solvents in the aqueous layer during extraction and will only be soluble in the water. As a result, this enables caffeine to be isolated from the tea bag.
Afterwards, the second step of this mechanism would be the extraction process where caffeine is separated from other organic compound in the tea by selectively dissolves the mixture into an appropriate solvent that can help separating the targeted organic
compound, in this case caffeine. The extract is the solution where caffeine dissolved in, and it is obtained in the separation funnel. In the case of this experiment, dichloromethane (CH2Cl2) was chosen as the solvent to separate the caffeine from aqueous extract of tea (tea that has been brewed) because caffeine is more soluble in dichloromethane (with its solubility value of 140 mg/ml) than in water (22 mg/ml). When dichloromethane (CH2Cl2) was added into the separation funnel, it was seen that two distinct layers would be formed as shown in the figure. By following the basis of different densities of dichloromethane (CH2Cl2) and water caffeine mixture can
be
separated
by
draining
out
the
dichloromethane (CH2Cl2) solvent through the funnel and therefore extracted from the tea sample. In this case,
since
dichloromethane
is
a
non-polar
substance, which is much denser than water and therefore
insoluble
in
it,
the
dichloromethane
(CH2Cl2) solvent containing the caffeine will be located on the bottom layer present in the separation funnel.
Lastly, the pure caffeine sample that is extracted from the tea can be obtained by distillation and oven. Actually after the extraction process, the lower layer containing dichloromethane (CH2Cl2) solvent and caffeine also contain some water molecules as water and dichloromethane is slightly soluble in each other. Therefore to obtain the pure caffeine sample, firstly, the lower layer was put into the distillation unit as distillation is a commonly used method for purifying liquids and separating mixtures of liquids into their individual components therefore separating the caffeine and water from the organic solvent, dichloromethane (CH2Cl2), which is not needed as the product of the extraction process. But since some residual water still present with the caffeine sample, the caffeine sample obtained after the distillation process has finished was further placed in the oven to remove those residual water therefore allowing us to obtained the caffeine sample, in this case of this experiment 0.0352 g of caffeine was extracted from 1.79 g of tea bag.
Unfortunately there were some errors from our experiment as it was seen in the figure that after the extraction process it was proven that the process did not give us the pure sample of caffeine, however there is other organic compound named tannin that was also
extracted thereby leaving some greencolored compound in the caffeine sample. This indicates that there were not
enough
amount
of
sodium
carbonate (Na2CO3) that was added during
the
boiling
process
which
causes the solution to be not basic enough therefore not all tannins were converted into its salt form which makes them to be still soluble in the solvent, dichloromethane (CH2Cl2) and thereby extracted when the organic layer (bottom layer present in the separation funnel) that supposed to be contained of the solvent and caffeine, also contained the tannin. Besides, there is also a possibility that not all caffeine was extracted through the separation funnel. In conducting this experiment, we only add 75 cm 3 of dichloromethane (CH2Cl2) into the funnel, however maybe more of dichloromethane (CH2Cl2) should be added into the funnel to ensure all caffeine were extracted.
VII.
Conclusion
Based of our experiment, the amount of caffeine contained in tea that was successfully extracted was 0.0352 grams from 1.79 grams tea, or only 1.96% out of 100%. There should be more caffeine that can be obtained from this experiment but we concluded that there were some errors occurred during the experiment like not all caffeine itself was dissolved completely in dichloromethane and the impurity of the caffeine sample as there is other substance like tannin that is also extracted during the extraction process. As a result ann optimum result was not obtained after the distillation process.
VIII.
References
Sutanto, Hery, and TablighPermana. Inorganic and Organic Chemistry 1 Laboratory Manual .Tangerang: Swiss German University, 2013. Print. "2 What the Purpose of Sodium Carbonate Added in Isolation of Caffeine from Tea Bag." Ask.com . N.p., n.d. Web. 11 May 2014.
. Altig, Jeff . "Isolation of Caffeine from Tea." Organic Chemistry Laboratory . N.p., n.d. Web. 10 May 2014. . "Caffeine -- History, Chemical and Physical Properties and Effects." Caffeine -- History, Chemical and Physical Properties and Effects . N.p., n.d. Web. 10 May 2014. . "Extraction of Caffeine from Tea." Nova Southeastern University . N.p., n.d. Web. 10 May 2014. . "Extraction." GEA Westfalia Separator Group . N.p., n.d. Sat. 10 May. 2014. . "Extraction of Caffeine from Tea." Value @ Amrita . N.p., n.d. Sat. 10 May. 2014. . "Extraction: Isolation of Caffeine from Tea." University of Delawara . N.p., n.d. Sat. 10 May. 2014. . "Patent EP2086561A1 - Topical formulation and uses thereof." Google Books . N.p., n.d. Web. 11 May 2014. .
