Set the flask in an ice bath to cool the mixture and speed crystallization. Felix Hoffman and Arthur Eichengrün first synthesized the active ingredient in aspirin, acetylsalicylic acid, in 1893. In Part 4, again, the issue where phenolphthalein only turns pink after the solution turns basic makes an appearance in the initial neutralization of the aspirin solution. . It would be expected that the willow bark would melt at a higher temperature that the crude aspirin as it is known to have more impurities.
The color we don't want! The range of melting points for the crude aspirin and product of willow bark in comparison to the pure aspirin is obvious and can show the level and amount of impurity in both compounds. Also, some benefits of aspirin are that it… 1796 Words 8 Pages Preparation and Recrystallisation of Aspirin Contents Page Synopsis iii 1 Introduction 1 1. Our purity percentage was 99. Additionally, the exothermic reaction of salicylic acid acetylation is not the sole process influencing the temperature, as the method assumes. Salicylic acid was neutralized with sodium to produce sodium salicylate, which was better-tasting but still irritated the stomach. Members of the class may have also utilized different techniques to measure the time taken for a 4 ˚C temperature change to occur. Write a structure for the ester formed from acetic acid and ethanol.
Additionally, it is possible that the aspirin never fully dried after the experiment, making the recorded mass of the aspirin higher and making the purity lower than the actual purity in the end. Add 10 mL of ethanol. The willow bark product displayed an intense black colour, possibly so purple it looked black, so far away from the pure aspirin colour that contaminations are certain. Polyesters are often made from dicarboxylic acids and diols. Before recrystallisation the crude aspirin could of included impurities such as: Acetic acid a product of the reaction process. Thus, it is doubtful that there are very many sources of error.
Remove all the liquid from the crystals by pressing with a clean stopper or cork. This is the second part of the purification process. National Reye's Syndrome Foundation, n. The Kolbe Synthesis for the production of salicylic acid was created by the German chemist Hermann Kolbe. When the aspirin was prepared, it was isolated and filtered. This method of forming acetylsalicylic acid is an esterification reaction.
This method of forming acetylsalicylic acid is an esterification reaction. Also, calculations of the theoretical yield and percent yield were done. The water bath temperature should not exceed 50 degrees Celsius. Then, the aspirin product was dissolved in water and titrated with both solutions to find the percent purity of the aspirin, which was found to be 99. Approximately 20 mL of acid was drained from the acid burette into the 100 mL beaker. The general mechanism for catalysation by a base, like the acetate ion or pyridine, is shown in Figure 2. Perhaps, the sample was not weighed properly or it was weighed when still wet.
The paper was moistened with distilled water. Place the 25 mL Erlenmeyer flask containing the product and ethyl acetate directly on the hot plate at 50 degrees Celsius. Some test tubes contained polymerized product that was not added to the flask. Weigh the weigh boat with sample inside and record the mass of the crude product formed. Can you predict how these groups affect the properties of the molecule and how the body reacts to it? The mass of pure acetylsalicylic acid was determined and recorded and the percent yield of the reaction was calculated Table 2. People with diabetes or risk factors like high blood pressure who are at a high risk for heart attacks can experience the benefits from taking aspirin daily. Make sure that the product is completely dissolved while gently and continuously heating on a steam bath.
These plants contain a compound called salicylate, which creates these curative attributes. The third factor that caused a low percent yield of our purified product was that when we vacuum filtered our purified product, some of our purified product fell through the filter and into the side arm flask. The filter paper and crystals were massed to determine the yield of acetylsalicylic acid. Step 6 The flask was removed from the water bath and 2 mL of ice-cold distilled water was added in a dropwise manner. Aspirin StructurePhenol Structure 2- Hydroxybenzoic Willow Bark Synthesis Acid structure Chemical tests 1. This clearly qualitatively shows the level of impurity as it is much heavier showing it contains other compounds weighing it down, which it should not have if synthesised meticulously. Taking this into account, the actual mass of the purified aspirin product is reduced to 0.
This occurs when someone has the chicken pox, the flu, or a cold occurs in these viral illness settings. Then the initial burette readings were recorded. Hoffman developed the process for the Bayer Company. Endothermic side reactions would retard the rate of temperature increase. Lower absorbance values would indicate that a greater concentration of phenol was present and the absorbance value could be used to directly determine the concentration 1 Cappelli, G.
The flask was allowed to cool for approximately 10 minutes. How did this affect the actual product yield? From this test it can be seen, to what degree each compound has a phenol impurity. The documented Rf for pure aspirin is 0. It is a white, crystalline, weakly acidic substance which melts at 135°C. The history of aspirin began in 1763 when Edward Stone wrote a paper to the Royal Society of London that claimed that willow bark could cure ague, which is now known as malaria. Step 8 Step 10 The mixture was heated for 15 minutes in a bath of boiling water.
The Phenol compound was used as a comparison. Leave the 125 mL Erlenmeyer flask that contains the mixture in its ice bath and allow it to cool for an extra 5 minutes. In the reaction the hydroxyl group on the benzene ring in salicylic acid reacted with acetic anhydride to form an ester functional group. Why is it not necessary to measure the volume of acetic anhydride to two significant figures? Cool the mixture slightly in an ice bath until crystallization is completed. The purpose of the experiment was to synthesize tetraphenylcyclopentadienone from benzaldehyde and to run reactions on carbonyl containing compounds. A A B B A A 2 drops of phenolphthalein were added and the sample was titrated to a faint pink endpoint.