Aspirin Synthesis Essay Example

product. The first step of the experiment focuses on obtaining the crude product, also known as isolated aspirin. To obtain a purified product, one can recrystallize the crude product using hot ethanol.

Recrystallization, an essential method for purifying solid organic compounds, is employed to remove impurities from compounds obtained from natural sources or reaction mixtures. These impurities may be insoluble, soluble, or colored. To ensure purity, each type of impurity must be eliminated separately during the recrystallization process. In the second part of the experiment, both the purified recrystallized aspirin and the crude aspirin will be utilized while retaining their and contents.

Determining the melting point of a solid is a common method used to identify and characterize compounds. Even small amounts of the compound can be used for this purpose. The melting point also indicates the purity of the compound. Impure compounds have lower melting points than pure compounds, and their range of melting points is wider. Pure compounds usually have a narrow melting point range of 1-2?C. If a supposedly pure aspirin has a wide melting point range, it may need further purification or may not actually be aspirin.

C. Review of Related Literature

This section provides literature citations, related studies, and experiments on the topic. Aspirin is a widely-used over-the-counter drug that serves as an effective analgesic, antipyretic, and anti-inflammatory agent. The origins of aspirin can be traced back to the 18th century when the pain and fever-reducing properties of salicylic acid, which is found in willow tree bark extract, were discovered. In traditional medicine, tea made from willow bark was commonly used for treating headaches and other ailments.

However, salicylic acid had negative side effects such as irritation to the mouth, esophagus, and stomach lining as well as an increased risk of stomach lining hemorrhaging.

Acetylsalicylic acid has medicinal properties that are similar to salicylic acid but is less acidic and doesn't have an unpleasant taste or cause stomach issues. The drug's acidity is effectively hidden by the acetyl group when consumed, and it converts back into salicylic acid in the small intestine, allowing it to enter the bloodstream for pain relief. In a lab, aspirin can be created by esterifying salicylic acid with acetic anhydride, which involves combining an organic alcohol with an organic acid.

The behavior of compounds related to organic functional groups is determined by these groups. For example, the sour taste in lemons comes from citric acid, while specific esters like intergreen or vanilla have distinctive smells. The reaction process involves breaking apart a water molecule and connecting fragments of carboxylic acid and alcohol to create an ester. To speed up the reaction at an optimal rate, a small amount of phosphoric acid is used. Currently, aspirin is commonly used as salicylic acid because it causes less stomach irritation than pure salicylic acid.

Recrystallization, also known as fractional crystallization, is commonly used to purify solid organic compounds by using a solvent. The principle behind this method is that the solubility of most solids increases with temperature. In other words, as temperature rises, more solute can be dissolved in the solvent. Organic compounds typically have a precise melting point that can be accurately measured within a range of 1oC or better. This measurement can be easily done

using a simple apparatus and a small amount of material, such as a few small crystals. Melting point determinations are regularly conducted on solid organic compounds and comprehensive collections of melting points are available in reference books. One important application of melting points is to verify if an expected product has been produced through a preparative or isolation procedure.

A substance that is highly pure will have a specific melting point that does not change even after additional purification. On the other hand, impure substances have a wider range of temperatures at which they melt, typically lower than the true melting point of pure substances. Therefore, the sharpness of the melting point is vital in determining purity levels. When measuring the melting point, it is crucial to record the temperature range during which the substance goes from solid to liquid. The lower temperature within this range indicates when liquid first appears, while the higher temperature represents complete fusion from solid to liquid state. If the melting point range is less than 2oC, it is generally considered sufficiently pure for most purposes. However, if there is a wide range observed, further purification becomes necessary. The same method used to assess purity in this experiment was also employed when evaluating aspirin quality.

Below, the study's methodology is discussed.

To make Reaction Aspirin, begin by measuring 3.0 grams of salicylic acid and placing it in a 250 mL Erlenmeyer flask. Then, pour in 6.0 mL of acetic anhydride (It is crucial to do this step in the hood). After that, cautiously add 5-10 drops of phosphoric acid and swirl the mixture to ensure thorough blending.

Lastly, heat the mixture for approximately ten minutes in a warm water bath with temperatures ranging from 70?C to 80?C.

After heating, add 20 drops of distilled water and then another 20 mL of distilled water. Cool the mixture in an ice bath and encourage crystallization by scraping the walls of the flask with a stirring rod. Use a pre-weighed filter paper to filter the solid aspirin. Rinse the crystals with 2-3 mL of cold water. Ensure that both the solid and filter paper are completely dried.

II. Determination of Yield: Pre-weigh a watch glass. Place the filter paper with the solid aspirin on it and weigh. Acquire the weight of the aspirin. This impure aspirin still contains traces of water and salicylic acid. Put a small amount of this impure aspirin in a beaker, cover with tissue, and set aside for further purification.

The impure aspirin is moved to a 100 mL beaker. Then, 10 mL of 95% ethanol is poured into the same beaker. The mixture is warmed in a water bath so that the crystals dissolve, without boiling it. If not all the crystals dissolve, an additional 5 mL of ethanol is added and the mixture is warmed once again. Once all the crystals have dissolved, 20 mL of warm water is included in the beaker. A watch glass covers the beaker and lets the mixture cool down slowly. Eventually, aspirin crystals will form. The solution continues to cool down in an ice bath. The pure aspirin gets filtered using filter paper that was weighed beforehand. Next, the crystals are dried and put into a covered beaker with tissue for further

drying.

To fill a capillary tube, press the open end into a mass of substance crystals. Then, drop the tube with the open end facing up down a glass tube that is about 1 cm in diameter onto a hard flat surface. This action will cause the crystals to settle at the bottom of the capillary tube. Make sure to tightly pack the sample to a depth of 2-3 mm.

B. II. Oil Baths can be created by pouring enough oil into a beaker so that the sample will be fully immersed. Boiling chips should be added and the mixture should be heated.

B. III. To determine the approximate melting point, place a pinch of the sample on the thermometer bulb and heat it until it completely melts.

B. IV. For the actual melting point range, prepare 2-4 capillary tubes by sealing one end of each with a blue flame. Pack these capillary tubes with aspirin - use 2 for the impure sample and 2 for the pure sample. Attach these tubes to the thermometer bulb and immerse them into an oil bath. Occasionally stir the oil to ensure even distribution of heat. Observe closely as the solid in the capillary tubes starts to melt and record both when it begins to melt and when it fully turns into liquid.

Regarding the data and results, a discussion will follow.

In summary, when salicylic acid reacts with acetic anhydride, it forms acetylsalicylic acid and acetic acid as a by-product. Like other organic compounds, the yield of this reaction is less than 100%. The resulting aspirin must be washed to

remove any extra acetic anhydride and acetic acid. It's crucial to purify the product before using it for anything other than experimentation because impurities are expected in the reaction products. Recrystallization is a very effective method for purifying substances.

The melting point determination is a useful test for assessing the purity of substances, including this "purified" substance. By comparing the melting points of both the crude and pure aspirin to the accepted value, it was observed that the pure aspirin's melting point closely matches the true value. However, despite this disparity, it was deduced that impurities still exist in the "purified" aspirin, emphasizing the need for further purification to achieve the experiment's objective.

Caution should be exercised when handling the reactants and catalyst in this experiment to prevent irritation if they touch the body. Also, make sure to pack the capillary tube properly to avoid air between sample particles, as this can lead to a higher thermometer reading than the actual temperature. It is important to carefully observe changes during the reaction process and melting point determination for accurate experimental data.