Aspirin

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

A cold, wet pipe cleaner was then added to the top of the reaction flask to keep the column cold which caused no vapors to rise into the column.

Aspirin is one of the most consumed painkillers created up to this date due to its reliability and low expense. It is often used to relieve minor aches and pains, reduce fever and as an anti-inflammatory medication. Due to its wide range of uses, the demand for this pharmaceutical is very high. As a result, manufacturers who produce this drug must be efficient in order to reduce the time taken to produce this drug and produce the in very high quantities.

The purpose of this lab was to synthesize aspirin, determine the theoretical yield, compare the percent yield to the theoretical yield and test the purity of aspirin by adding Iron (III) chloride to the product.

First, all of the equipment was obtained and placed on the table. The necessary equipment was weighed using a top loader balance, which used grams as its unit of measurement. The test tube, which held the samples, was filled with water from a plastic squirt bottle. A piece of filter paper, which had been folded several times, was placed over a funnel over an Erlenmeyer flask to filter the mixture in the test tube. The test tube mixture was poured onto the filter paper.

The pipet was put into the top of the condenser and leaving no open spaces. The vacuum served to get rid of the nitrogen oxide gases that were formed during the oxidation reaction. The solution was heated for 30 minutes, beginning the time when the first sign of nitrogen oxide fumes were observed. After the 30 minutes, the solution was removed and cooled for a few minutes. The solution turned was a brownish-yellow color and all the crystal were dissolved, leaving a liquid. The solution was then transferred, using a Pasteur pipet, to 3 mL of water in a beaker. The reaction flask was rinsed to remove the remainder of the solution. The solution was stirred with a glass rod until room temperature of the solution was achieved. A yellow solid was to form, but instead the solution remained aqueous in the case of the specific experiment explained here. With additional scraping of the solution with a glass rod, no crystals formed at all. The next procedure, if the crystals had formed was to crush the solid with the glass rod and filter the solid until the crystals were dry. The mass would then be weighed and the crystals were to be recrystallized with 95% ethanol. The crystals were to be cooled in ice water to get full crystallization and then the crystals were to be filtered and air dried, then weighed.

At this point the flask was attached to a refluxing apparatus. This process of refluxing helps to purify the mixture and keep the reaction at a constant temperature. Also, before the reaction mixture began to boil the separation of a clear top layer and a cloudy bottom layer helped to indicate that the reaction was working properly. The top layer was the alkyl bromide since the other components of the aqueous layer have the greater density. After the 45 minute refluxing process was complete, the apparatus was set up for simple distillation apparatus distillation commenced. Distillation took place until no more drops of product were dripping from the distillation head. The first drop of distillate occurred when the thermometer read 75°C, the actual temperature was probably a bit higher since the vapors might not have fully reached the bulb of the thermometer. The final drop of distillate was collected at about 115°C. Once the distillate was collected, it was placed in a seperatory funnel and the reaction flask was rinsed with 10 mL of water and added to the seperatory funnel. Rinsing the funnel ensured that all of the distillate from the distillation process was removed from the reaction flask and no product was left on the walls of the flask. After the water was added, two layers formed in the funnel. The top layer was the water and the bottom layer was the 1-bromobutane since the density of 1-bromobutane is higher than that of water.

It was observed that the solution turned a strong purple tint as the reflux continued, turning extremely dark at certain points. At the end of the 15 minutes, the reflux was stopped and the round bottom flask was allowed to cool to room temperature. Afterwards, the flask was placed in an ice bath in order to allow a precipitate to form, and it was observed that an extremely slight precipitate formed at the bottom of the flask. The mixture was then poured into a Buchner funnel attached to a Buchner flask in order to perform a vacuum filtration. The collected precipitate was further washed with 10 mL of cold DI water and 10 mL of cold ethanol.

In a hood, the mixture was heated in a hot-water bath for 10 minutes. After heating, the flask was allowed to cool in an ice-bath. P-acetamidobenzenesulfonamide was collected with the use of a Buchner funnel. The solid was then transferred into a 25-mL round-bottom flask and 5.3 mL of aqueous hydrochloric acid was added along with a boiling stone. A condenser was attached to the flask, and the solid was heated on heating mantle until it dissolved.

The tub was filled with just barely enough water, more or less than a quarter of the way full. The 1,000ml graduated cylinder, however, was filled to the brim and was subsequently placed upside down on the small tub of water. The amount of water inside the 1,000ml graduated cylinder was recorded. With the tub and graduated cylinder secure, the reactants of magnesium and hydrochloric acid were gathered.

One milliliter of 6.00-M phosphoric acid was placed into a 125-mL Erlenmeyer flask using a volumetric pipette. Using a slightly larger pipette, six milliliters of 3.00-M sodium hydroxide was transferred into a 50-mL beaker. Then a disposable pipette was used to slowly mix the sodium hydroxide into the phosphoric acid while the solution was swirled around. Then both the beaker and flask were rinsed with 2-mL of deionized water and set aside. A clean and dry evaporating dish was weighed with watch glass on a scale. Then the solution was poured into the dish and the watch glass was placed on top. The solution was then heated with a Bunsen burner to allow for the water to boil off to reveal a dry white solid. After the dish cooled to room temperature it was once again weighed and the new mass was recorded.

An ice bath was prepared in a large beaker and a small cotton ball was obtained. 0.5 g of acetanilide, 0.9 g of NaBr, 3mL of ethanol and 2.5 mL acetic acid was measured and gathered into 50mL beakers. In a fume hood, the measured amounts of acetanilide, NaBr, ethanol and acetic acid were mixed in a 25mL Erlenmeyer flask with a stir bar. The flask was plugged with the cotton ball and placed in an ice bath on top of a stir plate. The stir feature was turned on a medium speed. 7mL of bleach was obtained and was slowly added to the stirring flask in the ice bath. Once all the bleach was added, stirring continued for another 2 minutes and then the flask was removed from the ice bath and left to warm up to room temperature. 0.8mL of saturated sodium thiosulfate solution and 0.5mL of NaOH solution were collected in small beakers. The two solutions were added to the flask at room temperature. The flask was gently stirred. Vacuum filtration was used to remove the crude product. The product was weighed and a melting point was taken. The crude product was placed into a clean 25mL Erlenmeyer flask. A large beaker with 50/50 ethanol/water

Crystals were collected in a Buchner funnel, washed with alcohol, then ether, then transferred into a sample tube for storage.

Equipment, Materials, and Method The equipment used were a jacketed batch reactor beaker, cooling water circulation system, computer, LabPro temperature probe and conductivity probe, mixing stand and magnetic stir bar. The materials used for this reaction were a 0.08M NaOH solution and a 0.1M ethyl acetate solution. A 20% excess Ethyl acetate was used to ensure NaOH was the limiting reactant.[1] NaOH was chosen for the limiting reactant because of its high conductivity relative to Ethyl acetate. The extent of the reaction was monitored by measuring the conductivity throughout the reaction. With NaOH being the limiting reactant, the change in conductivity is more visible, and the termination of the reaction can