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 : Mr. Hery Susanto M.Si : Mr. Tabligh Permana, Permana, Mr.Hery Sutanto M.Si : Life Science/LS 2A : 11 March 2014 : 25 March 2014 : 2 : 14.00 17.00 p.m –
Experiment:
Preparation of Aspirin
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 the methods used for the synthesis of aspirin in laboratory.
Theoretical Background
Aspirin
Aspirin is a medicine that relieves pain and reduces fever. It is used to relieve many kinds of minor aches and pains — headaches, toothaches, muscle pain, menstrual cramps, the joint pain from arthritis, and aches associated with colds and flu. Some people take aspirin daily to reduce the ri sk of stroke, heart attack, or other heart problems.
Aspirin-also known as acetylsalicylic acid-is a synthetic organic derived from salicylic acid. Salicylic acid is a natural product found in the bark of the will ow tree and was used by the ancient Greeks and Native Americans. Aspirin belongs to a group of drugs called salicylates. Other members of this group include sodium salicylate, choline salicylate, and magnesium salicylate. These drugs are more expensive and no more effective than aspirin. However, they are a littl e easier on the stomach. Aspirin is quickly absorbed into the bloodstream and provides quick and relatively longlasting pain relief. Aspirin also reduces inflammation. Researchers believe these effects come about because aspirin blocks the production of pain-producing chemicals called prostaglandins.
In addition to relieving pain and reducing inflammation, aspirin also lowers fever by acting on the part of the brain that regulates temperature. The brain then signals the blood vessels to widen, which allows heat to leave the body more quickly.
To synthesize aspirin, a common analgesic drug, there are three parts of experiment that involved: the preparation of aspirin, the recrystallization of aspirin, and the estimation of the purity of the final product. Aspirin can be made by reacting salicylic acid with acetic acid in the presence of an acid catalyst; can be phosphoric acid, H3PO4, or sulfuric acid, H2SO4. The phenol group on the salicylic acid forms an ester with the carboxyl group on the acetic acid.
Esterification of Aspirin Using Acetic Anhydride Recrystallization
Primarily recrystallization is a process of purifying compound in the laboratory by forming precipitate. In this experiment, recrystallization process is used to recrystallize the target product in order to be separated from its impurities. It seen in the figure below that salicylic acid is the l imiting reactant and the acetic anhydride is excess. After the reaction (heating period) is over, the excess unreacted acetic anhydride will be destroyed by the addition of water to the mixture: water reacts with acetic anhydride to form 2 molecules of acetic acid.
Decomposition of Unreacted Acetic Anhydride When the esterification reaction is complete, cold water will be added to the mixture to allow recrystallization process to happen, as the additions of water cause the precipitation of the acetylsalicylic acid and will react with any remaining acetic anhydride.. Vacuum Filtration
Vacuum filtration is a technique for separating a solid product from a solvent or liquid reaction mixture. The mixture of solid and liquid is poured through a filter paper in a Buchner funnel. The filter traps the solid and the liquid is drawn through the funnel into the flask below, by a vacuum. In this experiment, the solid aspirin will be collected using vacuum filtration. Any other reaction ingredients that are soluble (this includes acetic acid, phosphoric acid, and water) will pass through the filter paper. Finally, the collected aspirin will be tested for its purity using FeCl3 (aq). Iron (III) ion reacts with phenols to form a purple complex. Salicylic acid contains a phenol group, but acetylsalicylic acid does not. Therefore, the addition of FeCl3 to an aspirin sample and the purple color changed means that there is still some salicylic acid present and the sample is impure. If aspirin is obtained, the aspirin then will be again purified by recrystallization. In this purification method, the crude aspirin will be dissolved in a small amount of warm ethanol. Water will then be added and the solution will
be cooled slowly and then chilled. The acetylsalicylic acid will recrystallize, and the solid impurities (unreacted salicylic acid) should remain dissolved in the solution. The solid aspirin will again be collected using vacuum filtration and tested for purity. This aspirin should be more pure than the original aspirin.
III.
Equipment and Materials
Equipment:
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Petri dish
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Volumetric flask, 100 cm3
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Volumetric flask, 25 cm3
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Volumetric pipette, 3, 5 cm3
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Graduated pipette, 25 cm3
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Erlenmeyer flask, 100 cm3
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Bulb, 4
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Round bottom flask, 2
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Beaker glass, 3, 1000 cm3
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Beaker glass, 4, 50 cm3
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Reflux pipe (condenser), 2
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Burette Clamp, 2
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Water cooler (thermostat)
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Plastic water hose, 3
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Hot plate, 2
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Spatula
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Digital Balance
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Vacuum filtration unit
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Filter paper, 2
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Test tube, 1
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Magnetic stirrer, 2
Materials:
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Vaseline wax
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FeCl3(l), Iron(III) Chloride
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C7H6O3(s), Salicylic Acid, 2 g
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H2O(l), distilled water, 750 cm3
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H2O(l), cold distilled water, 100 cm3
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C4H6O3(l), Acetic anhydride, 3.0 cm3
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H2SO4(l), concentrated sulfuric acid, 1 cm3
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C2H5OH(l), ethanol (96%), 20 cm3
IV.
Procedures
1. Step 1: Preparation of Equipment and Materials
1. Using a bulb and a graduated pipette in the lab hood, 20 cm3 of C2H5OH(l), ethanol (96%) was placed into the 25 cm3 volumetric flask. 2. The volumetric flask was labeled with “flask 1” label. 3. 100 cm3 distilled water, H2O(l),, was poured into the other volumetric flask with the size of 100 cm3 4. The volumetric flask was labeled with “flask 2” label. 5. Both “flask 1” and “flask 2” were placed inside the refrigerator in order to cool them. 6. Both beaker glass with the size of 1000 cm3 was half filled with distilled water, H2O(l),, and each of them was placed on top of a hotplate . 7. One magnetic stirrer was placed inside each of the beaker glass. 8. The beaker glasses in step 6 were heated until boiling up to a temperature of 350 0
C.
9. While waiting for the water to boil, the experimental setup was set according to the figure shown below
10. The thermostat connected to the two water hose was set to the temperature of 5 0C.
11. 1 g of C7H6O3(s), Salicylic Acid was placed on top of a petri dish using a spatula to be measured on the digital balance and was placed into the round bottom flask which was labeled with “flask 1”. 12. The previous step was repeated but the substance was placed on the other round bottom flask which was labeled with “flask 2”. 13. 1.5 cm3 C4H6O3(l), Acetic anhydride was taken by using , 5 cm3 volumetric pipette and placed into the round bottom flask which was labeled with “flask 1”. 14. The previous step was repeated but the substance was placed on the other round bottom flask which was labeled with “flask 2”. 15. 600 cm3 H2O(l), distilled water was inserted into each round bottom flask. 16. Lastly, 0.5 cm3 concentrated sulfuric acid, H2SO4(l), was taken using 5 cm3 volumetric pipette and placed into the round bottom flask which was labeled with “flask 1”. 17. The previous step was repeated but the substance was placed on the other round bottom flask which was la beled with “flask 2”. 18. After the water in each 1000 cm3 beaker that were placed on top of the hot plate were boiling, the magnetic stirrer present inside the water was removed and then the surrounding surface of the end of the reflux/condenser pipe and on t he mouth of the round bottom flask were rubbed by Vaseline wax. 19. Slowly each round bottom flask was placed on the end of the reflux/condenser pipe until its surfaces that was previously rubbed by Vaseline wax stick together but it was ensured that half of its bottom surface was inside the boiling water. As shown on the figure below
20. For about 20 to 30 minutes, the mixture was heated under reflux while steadily stirred by shaking both of the round bottom flasks. 2. Step 2: Recrystallization procedure
1. Each of the solution that was present in each flask was left to cool in room temperature. 2. After the temperature of the solution cooled, it was poured into two separate glass beaker with the size of 50 cm3, each labeled with “beaker 1” and “beaker 2” 3. 50 cm3 of the 100 cm3 H2O(l), cold distilled water, that was placed previously inside the refrigerator was poured into “ beaker 1” while the solution that was present inside being mixed together. 4. The previous step was repeated by using the other flask (“ beaker 2”) and also the leftover 50 cm3 H2O(l), cold distilled water. 5. The solutions that were present inside each glass beaker were stirred constantly until white precipitation appears making the solution cloudy, full of white flakes. 3. Step 3: Vacuum Filtration
1. The vacuum filtration setup was set according to the figure shown below
2. A filter paper was used to collect the crystals from the recrystallization process, the filter paper was folded twice and half of the side of the filter paper was ripped to decrease the edge that was formed when filter paper was inserted to the funnel. 3. Filter paper was inserted into the funnel that was placed on top of the large Erlenmeyer flask. 4. H2O(l), distilled water was sprayed on the inner side of the filter paper to make it stick on the funnel inner surrounding 5. The solution from the beaker glass, “beaker 1”, was pour a little by little into the funnel passing the wet filter paper into the larger Erlenmeyer flask right below the funnel 6. The solution was added slowly to ensure that no solution spilled into the outside surface of the filter paper 7. Once all solution was filtered, the wet filter paper was removed from the filter setup and the remaining solution in the larger Erlenmeyer flask was discarded 8. The crystals that were filtered and present on the filter paper was placed on a small beaker glass, labeled “beaker 1a” 9. The previous steps (2nd up to the 8th step) were repeated for the other beaker glass, “beaker 2” and placed in another new glass beaker, labeled “beaker 2a” 4. Step 4: Proving the Obtained Aspirin 1. The precipitation that was collected in both “beaker 1a” and “beaker 2a” was washed with 5 cm3 H2O(l), cold distilled water
2. The previous step was repeated but this time each solution in both “beaker 1a” and “beaker 2a” was washed with 10 cm3 of the 20 cm3 the C2H5OH(l), ethanol (96%) that was previously placed in the refrigerator (another volumetric pipette with size of 5 cm3 was used to obtain the substance from the volumetric flask). 3. The crystals that were obtained from both recrystallization and vacuum filtration were placed and combined into one test tube 4. Few drops of FeCl3(l), Iron(III) Chloride that was taken using a dropping pipette was added into the test tube containing the crystals. 5. The change of the color was observed to test the purity of the obtained Aspirin.
V.
Observation (Data)
Changes Observed
When the substances were heated under reflux for During the reaction (When the substances are placed inside the round bottom flask were heated under reflux)
about 20 to 30 minutes, the substance at the bottom side of the round bottom flask changed color into dark brown indicating changes that is formed due to the chemical reaction. Precipitation is found in one of the beaker but after it is filtered it is found out that no crystals or containing
Recrystallization Process
Aspirin and its other side product (i.e. Salicylic acid) is filtered and present in the filter paper. So the 4th step was not conducted in this experiment since there is no
Vacuum Filtration Process
Aspirin and its other side product (i.e. Salicylic acid) is produced.
VI.
Discussion
According to the observation shown in the data table above, it is concluded that there is no Aspirin and its other side product (i.e. Salicylic acid) that is produced from this experiment. It is because even though precipitation is found during the recrystallization process it does not necessary mean that it is the actual product that supposed to be obtained from this experiment. Some factors that contribute to the fail of this experiment can be observed from the steps of the procedure, which are; preparation of the substance, equipment, and materials needed, recrystallization, and vacuum filtration. During the first step of the experiment, all the substances present inside each round bottom flask; 1 g C7H6O3(s), Salicylic Acid, 1.5 g C4H6O3(l), Acetic anhydride, and 0.5 cm3 H2SO4(l), concentrated sulfuric acid that act as a catalyst, is heated in 600 cm3 boiling water. The present of high temperature as a result from the boiling water in the surrounding
of the round bottom flask and concentrated sulfuric acid, H2SO4(l) that act as catalyst that speed up the reaction along with becoming an intermediate in the complex series of reaction that happen during the synthesis, allow the reaction of this experiment to be completed forming Aspirin, shown in the figure below.
However in the case of this experiment, the reaction that happen does not proceed in a way that it supposed to be or in other words the reaction is incomplete. It is due to the fact that the reactants, present in each round bottom flask, are unable to mix and react together when it is heated under reflux even when they are placed in a favorable environment condition, as the round bottom flasks that were attached to the reflux/condenser were not steadily stirred by shaking both of the round bottom flasks. The stirring of the mixture present inside both round bottom flasks is a crucial step in this experiment because it is the way for the reactants to be able to mix together and react properly because by stirring the mixture it causes collision between the particle of the reactants, that allow them to perform chemical reactions which involve breaking and making bonds as stated by the collision theory. As a result even when all the necessary condition for this experiment is followed, the reaction cannot occur properly and form the product of the reaction. In addition, during this process there are too much catalyst, sulfuric acid, H 2SO4(aq) that is used inside this experiment, as a result the sulfuric acid, H2SO4(aq), that was supposed to act as the catalyst which increase the speed of the reaction disturb the reaction by reacting (undergoing chemical change) thereby causing the reaction to be incomplete. The very high temperature of the hot plate used to heat the solution also become the other factor that contribute to the downfall of this experiment. It is because the high temperature that is way too high cause the Vaseline wax that is rub around the end of the reflux/condenser pipe and on the mouth of the round bottom flask to melt and react with the mixture inside the flaks thereby disturbing the reaction
which eventually cause the reaction to be incomplete.
The downfall of this experiment can be proven further in the next step of this experiment, which is recrystallization and vacuum filtration. In the recrystallization process, the solution containing all the reactants were cooled in room temperature with the help of the cold distilled water H2O(l) that was added afterwards. When cold distilled water, H2O(l) was added while steadily stirring the solution, it was seen that there is a white precipitation that appears which make the solution cloudy and full of white flakes. Additionally, the cold distilled water, H2O(l) that was added also serve as a substance that help to remove the excess, unreacted C4H6O3(l), Acetic anhydride in this experiment by hydrolyzing it into Acetic acid, CH3COOH when it reacts with the water. Hot distilled water, H2O(l) is not used instead of cold one because hot water will not allow the solution to undergoes recrystallization. Furthermore, the addition of hot distilled
water, H2O(l) will not remove the excess, unreacted C4H6O3(l), Acetic anhydride in this experiment, instead it will dissolve the Acetic anhydride, C4H6O3(l) due to the high temperature that it has. However, in the end of the process it is found that there is also a possibility that the main substances used as the reactants in this investigation is not a pure substances . Because the crystallized precipitation that formed during recrystallization process was proven for not containing aspirin that we want and it is actually still containing more impure sample than the aspirin or even without containing the aspirin.
This is proven when the vacuum filtration process that when the crystals, formed during recrystallization, is filtered through the filtration unit no crystal-like structure are found from both solution in both round bottom flasks that is trapped in the filter paper. During the process it is found that all the
substances inside the solution like water (H2O(l)), concentrated sulfuric acid (H2SO4(l)), acetic anhydride (C4H6O3(l),) that is hydrolyzed into Acetic acid (CH3COOH), including the white precipitate which has a possibility being the Salicylic acid (C7H6O3(s)) or the Aspirin (C9H8O4(s)) were filtered down, passing through the filter paper unfiltered into the large Erlenmeyer flask beneath. Therefore the vacuum filtration unit that was used in order to remove the impurities or other side products of the experiment (other substances beside Salicylic acid (C7H6O3(s)) or the Aspirin (C9H8O4(s)) did not work as it is supposed to as no Salicylic acid (C7H6O3(s)) or the Aspirin (C9H8O4(s)) is found to be present on the filter paper.
The fall of this experiment finally forbid the conduct of the last step of this experiment which is proving the obtained Aspirin. If Salicylic acid (C7H6O3(s)) or the Aspirin (C9H8O4(s)) is found to be present on the filter paper indicating a possibility of the success of the experiment, this last stage can be used to prove whether the Aspirin that is obtained is pure or not. Basically there are several steps that is used, firstly the crystals that were supposed to be produced are wash with 5 cm3 H2O(l), cold distilled water and 10 cm3 of the 20 cm3 the C2H5OH(l), ethanol (96%) that was previously placed in the refrigerator. Cold water is used to wash the obtained crystals instead of hot distilled water to prevent the dissolution of the crystal that led to the need of repeating the vacuum filtration once more. Whereas the 10 cm3 of the 20 cm3 the C2H5OH(l), ethanol (96%) was added in order to remove the unneeded Salicylic acid (C7H6O3(s)) as it is able to interact with the hydroxyl (-OH) group of the Salicylic acid, enabling it to be removed from the crystal when washed away with the ethanol solution. Finally the addition of few drops of FeCl3(l), Iron(III) Chloride into the solution allow us to check the purity of the Aspirin (C9H8O4(s)) produced by looking at the color change that is produced when FeCl3(l), Iron(III) Chloride is added into the solution. It is because when phenol (benzene group that has a hydroxyl group attached to it) group of the excess Salicylic acid (C7H6O3(s)) react with FeCl3(l), Iron(III) Chloride, it turn the color of the solution into purple, and the more purple it becomes it indicates more Salicylic acid (C7H6O3(s)) that is not yet removed from the solution or in other words higher impurity of the Aspirin (C9H8O4(s)) produced.
VII.
Conclusion
Aspirin is medicine from a synthetic organic derived from salicylic acid that could relieve many kinds of minor aches and pains. We synthesized aspirin through preparation of aspirin, recrystallization & vacuum filtration and finally the test of the purity of the aspirin produced. However, we did not do the third step of the experiment due to no existence of aspirin-crystal during filtration process. The several factors that may affect the end result of this investigation is primarily misconducting the procedure and the uncontrolled condition when conducting the reaction. As a result the reaction of C7H6O3(s), Salicylic Acid and C4H6O3(l), Acetic anhydride when they are heated under reflux become incomplete and did not produce the end product, which is the Aspirin (C9H8O4(s)). Other factors such as unstirred mixture, the too many catalyst, sulfuric acid, H2SO4(aq) that is actually used for increasing the rate of the reaction, impurity of the substances used as reactants, and finally the very high temperature that caused Vaseline wax to melt and react when it comes into contact with the heated mixture also contribute to the downfall of the experiment. In the other hand, if we succeed to filtrate the crystals and obtained the Aspirin (C 9H8O4(s)), we need to add a few drops of FeCl3(l), Iron(III) Chloride, to test its purity as there is a possibility that its side product which is Salicylic Acid. (C7H6O3(s),) may also present among the filtrate crystals. Finally t he color change indicates the purities of aspirin produced if it turns to dark purple it means that it contains a great amount of salicylic acid and if it turns to light purple it means it contains a small amount of salicylic acid. So, the lighter purple color we get, the purer aspirin we have.
VIII.
References
Sutanto, Hery, and TablighPermana. Inorganic and Organic Chemistry 1 Laboratory Manual .Tangerang: Swiss German University, 2013. Print. "Aspirin." ChemSpider . N.p., n.d. Web. 20 Mar. 2014.
. "ChemLab - Techniques - Vacuum Filtration." ChemLab - Techniques - Vacuum Filtration. N.p., n.d. Web. 22 Mar. 2014. . "Chemistry 104: Synthesis of Aspirin." Chemistry 104: Synthesis of Aspirin. N.p., n.d. Web. 22 Mar. 2014. . Fossum, Cheli. "Experiment 8 – Synthesis of Aspirin." Experiment 8 – Synthesis of Aspirin. Laney College, n.d. Web. 20 Mar. 2014. . "Synthesis of Aspirin." Synthesis of Aspirin. N.p., n.d. Web. 22 Mar. 2014. .
"Synthesis of Aspirin." Synthesis of Aspirin. N.p., n.d. Web. 22 Mar. 2014. . "Synthesis of Aspirin CourseNotes." Synthesis of Aspirin CourseNotes. N.p., n.d. Web. 22 Mar. 2014. . "aspirin playV2('en/US/d3/d3djsfshd7ssdnsfhn');playV2('en/UK/d3/d3djsfshd7ssdnsfhn')." TheFreeDictionary.com. N.p., n.d. Web. 22 Mar. 2014. ."recrystallize." The Free Dictionary. Farlex, n.d. Web. 22 Mar. 2014. .
