Lab Report 3 - Chem 223: Isolation Of Aspirin, Acetaminophen, And Caffeine PDF

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CHE 223 Lab Report Ysatis M. Fenner Title: Isolation of Aspirin, Acetaminophen, and Caffeine from Excedrin Tablet Performed: October 29th, 2018 Submitted: November 5th, 2018

Abstract: Excedrin, a drug that is often used, is said out to contain aspirin, acetaminophen, and caffeine. Through simple procedures including separation through gravity filtration, extraction of aqueous layer from organic layer, and vacuum filtration the percent yields of 31.0%, 8.0%, and 287.0% of the aspirin, caffeine, and acetaminophen components respectively assured the presence of all three compounds. For the unknown, Melting point method was then performed in order to guarantee the purity of the obtained components. To use techniques such as separation and purification to first identify the components in an Excedrin tablet. Melting point procedure will account of the purity of each component. The Thin Layer Chromatography (TLC) method will then be used to verify that the tablet does indeed contain the aspirin, acetaminophen, and caffeine components. Introduction: Part A The Excedrin tablet is a combination drug for the treatment of pain, promising to contain components of aspirin, acetaminophen, and caffeine. As many other pharmaceutical tablets, the Excedrin tablet is also held together by a binder, which is useful since it prevents the components from falling apart while swallowing or while it’s simply in its container. The binder is usually made from some sort of starch, microcrystalline cellulose and silica gel. It’s most valued property is that it’s insoluble in water and most common organic solvents. Since all components being measured for have different properties, we can use it to our advantage. The structures of aspirin, acetaminophen, and caffeine reveal that one is a base, the other is a strong organic acid, and one is a weak organic acid. Looking at the table of constants, one can see that the weak acid acetaminophen is insoluble in ether, chloroform, and dichloromethane so it cannot be extracted by a strong base. Due to this lack of solubility, we can dissolve the other two components, acetaminophen and caffeine, in dichloromethane to first remove the acetaminophen, by filtration. Luckily, the binder is also insoluble in dichloromethane but in treatment of ethanol the acetaminophen will dissolve while still maintaining the structure of the binder. The two can be separated by filtration, evaporating the ethanol in order to isolate the acetaminophen entirely. This part of the experiment is testing technique, as it is not easy to separate and crystallize a few milligrams of a compounds that occurs in a mixture.

Melting points are imperative for characterizing pure solid organic compounds along with other physical properties such a boiling points and density. The range of temperature is typically less than 1ºC, and if not it will be classified as an impure compound. The technique that helps reverse this is called recrystallization, which is a process involving a compound being purified along with its melting point (range) decreasing. Organic compounds usually melt below 300ºC and involve covalent bonding. Pure compounds will melt once the vapor pressure of the solid and liquid are the same. The Mel-Temp apparatus includes a thermometer and uses capillary tubes to hold the solid compounds, and a heating block. The obtained components of aspirin, caffeine, and acetaminophen will be observed through this manner to determine their purities. Once the components reach their melting points ranges, those ranges will then be compared to the known values for each component and check for purity. Thin Layer Chromatography (TLC) is an inexpensive analytical technique (qualitative) when carrying out organic experiments. This technique only requires micrograms of material in order to carry out the experiment. Some of the main use of this technique is to determine the number of components in a mixture, to determine the identity of two or more substances, to monitor the progress of a reaction, to determine the effectiveness of a purification, etc. A TLC is a sensitive and fast piece of equipment, and it involves a thin sheet of glass/plastic coated with a thin layer of absorbent, which is spotted near one end with the sample to then be analyzed. Once placed in a beaker containing the solvent and covered with aluminum foil, the solvent will rise up the TLC plate by capillary action. The solvents used to analyze analgesics tablets are usually characterized by having low boiling points along with low viscosities, which allow them to migrate rapidly. The order in which solutes migrate on thin-layer chromatography is the same as the order of solvent polarity. The largest Rf values are shown by the least polar solutes. As the procedure is in progress, one usually sees that the substance is pure if a spot traveling either along with the solvent front, or at the same distance behind the solvent front is noticed. The dots are then to be marked before the solvent evaporates to then calculate the rest of the Rf values. The Rf value is a ratio showing the distance the spot travels from the point of origin to the distance the solvent travels. Materials: Part A        

Balance: used to weigh out 1g of Excedrin 25-mL graduated cylinder: used to measure out 15mL of dichloromethane to add to the 1g Excedrin Hot plate: used in order to heat up the 1g Excedrin along with the 15mL CH2Cl2 mixture. 100-mL Erlenmeyer flask: was used to catch the filtrate from the mixture by Gravity Filtration. Stemless funnel: along with filter paper used to carry out Gravity Filtration of Solution 1 Spatula: used to scrape out powder from filter paper. Pipette: used to add the 6ml of NaHCO3. Separatory funnel: used to undergo extraction, separate aqueous layer from organic layer.

     

150-mL beaker: used to collect the aqueous layer. 50-mL beaker: used to collect the organic layer. Ice bath: used to cool 150mL beaker containing aspirin. Spatula: used to distribute drying agent into the organic layer as well as to scrape the residue into a 50mL beaker. Vacuum flask, Buchner funnel, filter paper, and rubber tubes: used as setup for vacuum filtration. 50-mL beaker: was used to carry the filtrate (acetaminophen).

Table of Physical Constants: Part A Name

Structure

MF

MW (g/mol)

Bp/Mp (ºC)

Density (g/cm3)

Aspirin

C9H8O4

180.5

140/135

1.4

Caffeine

C8H10N4O2

194.19

178/238

1.23

Acetaminophen

C8H9NO2

151.16

420/169

1.3

Dichloromethan e

CH2Cl2

84.93

39.6/-96.7 1.33

Ethanol

EtOH

46.07

Hydrochloric Acid

HCl

36.46

78.37/144.1 110/-26

1.19

Calcium Chloride

CaCl

110.98

1935/772

2.15

0.79

Procedure & Observations: Part A – Separation of Analgesics in Excedrin Procedure Observations  Using a balance, 1g of Excedrin was  Once the 1g Excedrin and 15mL of weighed and placed in a 250mL beaker. CH2Cl2 was heated, a large part of Graduated cylinder was used to measure the material did not dissolve. 15mL of dichloromethane (CH2Cl2).  More than recommended, 6mL of Mixture was then heated in steam bath. NaHCO3 instead of 2mL of  Once heated, the mixture was filtered NaHCO3 were used due to there not out by procedure of Gravity Filtration. A being a clear distinction between 100mL Erlenmeyer flask, stemless the aqueous and organic layer. funnel, and filter paper made up the  150mL beaker used to carry setup. Once filtered, the filtrate was aqueous layer empty =73.79g labeled Solution 1 (Aspirin + Caffeine).  150mL beaker with aspirin =  6mL of NaHCO3 was then added to the 74.10g filtrate containing the aspirin and  74.10g – 73.79g = 0.31g caffeine. A separatory funnel was then  50mL beaker used to carry organic used to perform an extraction of the layer empty = 29.07g aqueous layer from the organic layer.  50mL beaker with caffeine = Both layers were collected in 150mL 29.87g beakers.  29.87g – 29.07g = 0.8g  The aqueous layer was then treated with  50mL beaker used to carry HCl dropwise until no precipitation was acetaminophen empty = 29.02g present. The solution was then boiled in  50mL beaker used to carry order for it to dissolve. Once dissolved, acetaminophen = 31.89g solution was cooled to room  31.89g – 29.02g = 2.87g temperature in ice bath. Final product obtained was Aspirin.  The organic layer was collected in a 50mL beaker. Two spatulas’ worth of drying agent, CaCl2 was then added in order to purify the solution. The product was caffeine.  The powder on the filter (residue) was first allowed to dry and then using a spatula was scraped out. Powder transferred to 50mL beaker and 2mL of EtOH was added. Vacuum filtration was performed in order to obtain a filtrate of only acetaminophen. The filter paper held the binder.  The percent yield for all three components were then calculated.

Waste Disposal & Safety Precautions: Part A   

Dispose of any dichloromethane containing solutions in the halogenated organic waste container. Other organic liquids should be disposed of in the organic solvents container. The aqueous layer should also be disposed of in the organic waste container.

Results and Discussion: Part A Once the 1g of Excedrin was added to the 250mL beaker along with the 15mL of dichloromethane and then set to heat up, a large part of the material did not dissolve. The mixture was then filtered out by Gravity filtration, which then left us with a filtrate consisting of aspirin and caffeine along with a residue, being the acetaminophen and binder. The filtrate was then introduced to 6mL of NaHCO3, instead of the 2mL of NaHCO3 suggested by the procedure provided in class. The reason for this is that there was not a clear distinction between the aqueous and organic layer in the solution. Once that became clear, an extraction using a separatory funnel was performed in order to separate the aqueous layer from the organic layer. The aqueous layer was collected in a 150mL beaker. Hydrochloric acid was then introduced into the 150mL dropwise until no precipitation was present. The solution was then boiled to completely dissolved and shortly after that it was set to cool in an ice bath. The product obtained once the solution was cool was the aspirin. The 150mL beaker was weighed, using a balance, prior to collecting the aqueous layer. After the 150mL cooled it was weighed again. The difference obtained was 0.31g, giving us the amount of aspirin product obtained. The organic layer first collected in a 50mL beaker and was then treated with 2 spatulas’ worth of CaCl2. The inorganic compound, CaCl2, was also added with precaution as adding too much could result in the salt dissolving in solution therefore altering the purification of the organic layer. The 50mL beaker was weighed prior to collecting the organic layer and after. By subtracting those two values I was able to obtain a total of 0.8g of pure caffeine. The residue, once dried, was treated with 2mL of ethanol and vacuum filtration was performed in order to obtain a filtrate consisting of only acetaminophen. The solid residue obtained through vacuum filtration is the binder and therefore labeled as waste. The 50mL beaker used to carry the acetaminophen before usage was weighed out to be 29.02g. Once the filtrate (acetaminophen) was added and then weighed again, the recording was 31.79g. The difference gave us a total of 2.87g, which is the amount of acetaminophen product obtained. The theoretical yield is collected and calculated in order for researchers to determine the amount of product formed based on the reagents present at the beginning of the reaction. The equation used to calculate the percent yield is as follows. Below are the calculated yield percentages for all three components obtained, aspirin, caffeine, and acetaminophen.

The following formula used to solve problems in this experiment: % Yield =

Actual Yield ∗100 %=¿ Theoretical Yield

Data: Part A Aspirin:

% Yield =

0.31g ∗100 %=¿ 31.0% 1.00 g

Caffeine:

% Yield =

0.8 g ∗100 %=8.0 % 1.00 g

Acetaminophen:

% Yield =

2.87 g ∗100 %=287.0 % 1.00g

The percent yield for both aspirin and caffeine are both a reasonable percentage considering that there were other components within the Excedrin tablet therefore not expecting each component to be incredibly close to 100%. For the acetaminophen on the other hand, the yield percentage calculate turned out to be way over 100%, meaning that contamination or a missed step did occur. It could have been anything from the vacuum filtration not being out correctly to too much EtOH being added. Conclusion: Part A The crystallization of a pure aspirin compound from Excedrin tablet yielded 31.0% of product obtained from the reaction. Another product obtained from the reaction was caffeine, yielding at 8.0%. Notice that both of these values are below 100%, meaning that the presence of impurities is unlikely. Although I can assure that for now, the next part will include the method of Thin Layer Chromatography to determine presence of these compounds along with the melting point procedure done to measure if the compounds yielded really are as pure as we hope for. The percent yield for acetaminophen was way over 100%, it was 287.0%, meaning that the measure product of the reaction could definitely contain impurities which may have caused its mass to be greater than it actually would be if the product were pure.

Materials: Part B     

Weighing papers: used to hold sample amounts of all three components (aspirin, caffeine, and acetaminophen) Spatula: used to transfer all three components on to the weighing paper Capillary: tubes with a closed end used to collect small amounts of all three components (about 2cm worth) Long glass tube: used to assure that all of the substance’s compacted into the closed end of the capillary tube 150mL beaker: used to hold the solvent for TLC method

Table of Constants: Part B Name Ethyl acetate (95:5)

Structure

MF C4H8O2

MW (g/mol) 88.11

Bp/Mp (ºC) 76.5-77.7/ -84

Density (g/cm3) 0.897

Procedures and Observations: Part B Procedure  The Mel-Temp apparatus was first set up, thermometer was set in place.  Small amounts of all three components (aspirin, caffeine, and acetaminophen) were distributed on to separate weighing papers with metal spatula. About 2cm of each of the components were distributed into the closed end of capillary tubes. Long glass tube used to assure the substance’s compacted into the closed end of the capillary tube.  The capillary tube was then slid down the melting point tube and the MelTemp apparatus was switched on. The dial on the apparatus was turned to “4” and the temperature was observed carefully.

Observations  The caffeine sample was noticed to have contained some sort of moisture, making it impossible for it to reach the closed end of the capillary tube.  Caffeine component sample melting point range: Not collected.  Aspiring component sample melting point range: 141ºC - 172ºC.  Acetaminophen component sample melting point range: 158ºC – 167ºC.  No melting point for unknown, melted way too fast.

Waste Disposal & Safety Precautions: Part B    

Do not leave apparatus unattended if on. Do not heat apparatus above what the thermometer allows. Place organic solvents in the organic solvents container. Used TLC plates to be discarded in the non-hazardous solid waste container.

Results and Discussion: Part B The melting point method was conducted first in order to obtain a set of melting point ranges for all three of the components (aspirin, caffeine, and acetaminophen). I must mention that the thermometer placed in the Mel-Temp apparatus did not reach over 260ºC. It is recommended that the thermometer never reached full potential due to the possibility of if completely shattering. Once the temperature reached nearly 260ºC and no change had yet occurred decided to stop the procedure right there to prevent shattering. There was no melting point range obtained for the caffeine component sample. The melting point range of pure caffeine is said to be 238ºC. Since the thermometer passed that point and the crystals had not yet even begun melting, it’s safe to say that the caffeine component was not pure. The melting point range for the aspirin was 141ºC - 172ºC, and the melting point range obtained for the acetaminophen sample component was 158ºC – 167ºC. The melting point ranges obtained for both aspirin and acetaminophen components were not incredibly far from the recorded melting points of each component on the Table of Physical Constants while the melting point for the unknown was unable to be attained.

The following formula used to solve problems in this experiment: Distance traveled by component (cm) Rf = Distance traveled by solvent (cm) Data: Part B 7.0 cm 8.1 cm



R f aspirin =



R f caffeine =



R f unknown=



R f acetaminophen =undetectable

= 0.86 cm

2.1 cm =0.26 cm 8.1 cm 4.9 cm =0 .60 cm 8.1 cm

Conclusion: Part B The Mel-Temp apparatus was used to determine purify of the obtained compounds by analysis of the melting point range of each component. The melting point ranges obtained for aspirin (141ºC - 172ºC) and acetaminophen (158ºC – 167ºC) were not terribly off to those listed on the Table of Constants, but are still considered to be classified as impure since the difference in melting point range was large than 1ºC. The melting point for the unknown was undetermined. .

Reference: 

Fieser L., Williamson K. Organic Experiments. 7th Edition D.C. Heath and Company. 45-58. 189-193....