Experiment 3: The preparation of acetaminophen (paracetamol) with thin layer chromatography (TLC) to monitor the reaction.
Abstract:
This experiment is to demonstrate the preparation of paracetamol and its properties. Reflux and filtration of 4-aminophenol and acetic anhydride formed the crude sample. Further analysis of dry white crystals were used to give quantitative measurements and a percentage yield of 46% was obtained. The overall conclusion is that the acetic anhydride reacted with the –NH2 group.
Materials and Methods:
1. We weighed out (on a top-pan balance) 4-aminophenol (about 11.0g) in a weighing boat and transfer the powder to a 250cm3 round-bottomed flask (RBF) using a powder funnel. 2. Then recorded the amount
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-Sample + Ethanol= Colourless solution
FeCl3 was then added to this solution and a positive colour change was seen, as it turned green
-Sample + Ethanol + FeCl3 = Dark Green solution
This was then repeated using Salicyclic Acid instead of the sample to give a reference material as it will give a positive test for a phenol.
-Salicyclic Acid + Ethanol = Colourless solution
-Salicyclic Acid + Ethanol + FeCl3 =Purple solution
The positive colour change from colourless to dark green of the sample means that the phenol group is present in the sample. Therefore indicating that the acetic anhydride has reacted with the amino group.
3. Determine the melting point and record the infrared spectrum of the dry solid.
Melting Point:
The melting point of sample obtained is: 1680C
Literature Value: [1]: 169-1720C
Fig 1.1-Infrared Spectra of Paracetamol:
The infrared spectrum of paracetamol shows the appearance of a new peak at 1561 – 1650cm-1 this represents the carbonyl group from the acetic anhydride, meaning that paracetamol has been formed. The –OH peak is still present at 3109 – 3319cm-1 this shows that the phenol group is still attached to paracetamol. From the infrared spectra you can also see that the –NH2 group has disappeared. This is as it has been selectively acetylated by acetic anhydride to form paracetamol.
4. TLC Plate analysis and Rf values of important spots.
Fig 1.2-Thin Layer Chromatography of Student samples 1 and
Aspirin, Caffeine and Salicylamide were extracted from an over-the-counter pain reliever (BC Powder). These components were separated by manipulating their solubilities by adjusting the acidity and basicity of the solution. By doing this, the three components were forced into conjugate acid (or base) forms, causing selective solubility in either an aqueous or organic solvent. These layers were then separated by use of a separation funnel. Once separated, the components extracted were characterized by measuring the melting point and performing a TLC analysis. Also, the recovered aspirin from the first part of the experiment was recrystallized and compared to that of the
Separation and Purification of the Components of an Analgesic Tablet. Cora Bruno, Lab Section E. Aspirin, Caffeine and Acetaminophen were separated from four analgesic tablets of Excedrin using extraction techniques. 5% wt/vol NaHCO3, 4M HCL, ethyl acetate and deionized water were used to separate the three active components. MgSO4 was used to dry each extraction. Aspirin was isolated using a hot water bath and weighed to determine the percent theoretical recovery and the actual percent recovery of aspirin. After separation, Aspirin (ASA), Caffeine (CAF), and Acetaminophen (ACE) were purified and identified using Thin Layer Chromatography (TLC). Standards and purified ASA, CAF, and ACE were spotted on the silica gel (stationary phase) of the
Acetic Anhydride and p-Aminophenol were heated in a vial attached to an air condenser to synthesize crude acetaminophen, resulting in 0.097 grams (47.48% yield). The crude acetaminophen was then recrystallized in a solvent of water and methanol over heat resulting in 0.082 grams (39.61% yield) of pure acetaminophen. Melting points of both crude and pure acetaminophen were taken, and found to be 165.9 - 170.9°C and 168.2 - 171.5°C, respectively. The literature melting point of acetaminophen is 169.5 – 171.0°C, indicating that our final product was pure.
This experiment involved three steps: synthesis of aspirin, isolation and purification, and the estimation of purity of the final product. The synthesis involved the reaction of salicylic acid and acetic anhydride in the presence of a catalyst, phosphoric acid, H3PO4. When the aspirin was prepared, it was isolated and filtered. The percentage yield of the synthesis was calculated to be 78.42%. The experimental melting point range of aspirin was determined to be 122 -132°C. Due to its wide range, and lower value than that of the theoretical melting point of 136°C, it was
The goal of this experiment was to synthesize aspirin. In this experiment aspirin, also known as acetylsalicylic acid, was synthesized from salicylic acid and acetic anhydride. In the reaction the hydroxyl group on the benzene ring in salicylic acid reacted with acetic anhydride to form an ester functional group. This method of forming acetylsalicylic acid is an esterification reaction. Since this esterification reaction is not spontaneous, sulfuric acid was used as a catalyst to initiate the reaction. After the reaction was complete some unreacted acetic anhydride and salicylic acid was still be present in the solution as well as some sulfuric acid, aspirin, and acetic acid. Crystallization, which uses the principle of
The isosbestic point of the acid (pH6) and basic forms (pH10) of para Nitrophenol (PNP) was expected at 350nm. As you can see in figure 2, the graph shows the intersection of 2 curves at ~350nm, which is matched with the literature value. Also, the pKa of PNP was expected 7.15 at room temperature. Refer to figure 3, the pKa is estimated to be 7.15-7.2, which very close to the literature value. In addition, the lab was succeeded in illustrating the use of a spectrophotometry to analyze concentrations of chemical substance. The absorbances of 2 unknowns were felt on the standard curve as the expectation (refer to table 4). The minimum absorbance of the known standards was 0.193 and the maximum is 1.830. The absorbance of the unknown
This test is used to detect if the bacteria contains any deoxyribonuclease activity. Because no color change was observed from blue to clear my unknown bacteria displayed a negative result.
Both Aspirin and the Unknown are soluble in dichloromethane, due to their non-polar characteristics. To separate the two components, sodium bicarbonate was added (see figure 3). Sodium bicarbonate reacted with aspirin and converted it to a salt, also forming water and carbon dioxide. It was observed that the solution "fizzed" when this reaction took place, showing the release of carbon dioxide. The newly formed salt then traveled to an aqueous layer where it was soluble, while the unknown remained in the dichloromethane layer. The two layers were then separated. To collect an aspirin solid, the combination of the addition of HCl and the process of vacuum filtration helped to break down the salt and form a solid. Then the solid was placed in the Fisher Scientific Biotemp Oven to dry it to a constant mass of 0.091 g, 32.97% of the total composition. The
0.1 gram of commercial aspirin was weighed in a tray and was then added to a second test tube containing 2.0 mL of Iron (III) chloride, which was measured using a 10 mL graduated cylinder, to test for phenols. This was repeated once more to validate results.
Upon the addition of water, it was noted that a layer separation occurred and the water layer remained on top, with the 2-methylphenol layer on the bottom layer. Then, conversion calculations were performed to determine the appropriate amount of 3M NaOH to be added to the 2-methylphenol solution. From the calculations, it was determined that 1.08 mL were to be added. 3M NaOH itself was a cloudy solution in appearance and upon the addition of 3M NaOH to the 2-methylphenol solution, it was noted a color change occurred and it became a yellow-green solution. Following this, the same calculations used previously, were used to determine the appropriate amount of sodium chloroacetate, which was found to be 0.38 g (3.26 mmol). Sodium choloroacetate was a white, crushed solid that was then combined with 1 mL of water and was swirled until the sodium chloroacetate completely dissolved. This sodium choloracetate solution was then transferred to the 2-methylphenol solution by the use of a medicine
In this experiment, 0.31 g (2.87 mmol) of 2-methylphenol was suspended in a 10 mL Erlenmeyer flask along with 1 mL of water and a stir bar. The flask was clamped onto a hotplate/stirrer and turned on so that the stir bar would turn freely. Based on the amount of 2-methylphenol, 0.957 mL (0.00287 mmol) NaOH was calculated and collected in a syringe. The NaOH was then added to the 2-methylphenol solution and allowed to mix completely. In another 10 mL Erlenmeyer flask, 0.34 g (2.92 mmol) of sodium chloroacetate was calculated based on the amount of 2-methylphenol and placed into the flask along with 1 mL of water. The sodium chloroacetate solution was mixed until dissolved. The sodium chloroacetate solution was poured into the 2-methylphenol and NaOH solution after it was fully dissolved using a microscale funnel.
The objective of this lab is to synthesize acetaminophen from p-aminophenol. The techniques used to do so, consist of: reflux with heat to allow reaction to occur at a reasonable time period, extraction and filtration to isolate the desired product, and characterization of the product by analyzing IR spectras and melting points. Acetaminophen considered synthesized, primarily due to the IR spectrum exhibiting all the bond vibrations is the amide group. The percent yield of 124.6% imply that there was a mechanical error that occurred, thus, also tampering with the progression of the chemical reaction. The wide melting point range of 165 C-169 C denote the impurity of the acetaminophen product.
AIM: To extract codeine and paracetamol from its tablet by solvent extraction and tentatively identify in comparison to standards using Thin Layer Chromatography.
By using acid-base titration, we determined the suitability of phenolphthalein and methyl red as acid base indicators. We found that the equivalence point of the titration of hydrochloric acid with sodium hydroxide was not within the ph range of phenolphthalein's color range. The titration of acetic acid with sodium hydroxide resulted in an equivalence point out of the range of methyl red. And the titration of ammonia with hydrochloric acid had an equivalence point that was also out of the range of phenolphthalein.. The methyl red indicator and the phenolphthalein indicator were unsuitable because their pH ranges for their color changes did not cover the equivalence points of the trials in which they were used. However, the
The purpose of the experiment was to compare antacids by the amounts acid they neutralize to find the most effective antacid. Finding the most effective antacid is important because it will help others by allowing them to choose the best product for their heartburn. Titration is the process of which the unknown solutions concentration reacts with a known solution concentration. During the experiment, titration was used to calculate the moles of HCl neutralized by the antacid in this case was gelusil, by knowing the moles of HCl initially added to the flask and moles of HCl neutralized by the NaOH.