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Experiment 18 discussion aspirin
Organic Chemistry Lab II (CHEM201401)
Boston College
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Tyler Silverstein Organic Chemistry Lab II Brayan Rondon March 30, 2022 In this experiment, two esters were synthesized. In the first part, cholesteryl benzoate was synthesized reacting cholesterol with benzoyl chloride. When benzoyl chloride was added to the cholesterol, the solution was white and cloudy. This is due to the reaction to form cholesteryl benzoate. The solution became solid, and the addition of methanol caused the solid to break up. This is due to the solubility of the product with methanol. After recrystallization in ethyl acetate, the crystals were powdery, white, and shiny. The product then was observed for its liquid crystal properties. There was a shimmer of colors, but the dominant color was blue. The reason why there was color reflected is that in the liquid crystal phase, the crystals are ordered in a manner that reflects the blue light. The percent yield of cholesteryl benzoate was The yield was not bad but may have been lowered due to the loss of product when vacuum filtering twice and recrystallizing. The melting point of the purified product was The literature melting point is which indicates that the purified product may have had some impurities. Another reason for the lower melting point may be that the crystals were still wet with solvent. The melting point of the purified product with cholesterol was 126ºC127ºC. The melting point of the mixture was significantly lower due to the different crystal structures in the products and how they break the crystal lattice of each other, lowering the melting point. In the second part, acetylsalicylic acid was synthesized the esterification of salicylic acid with acetic anhydride. Solubility of the product was also tested. When the starting materials with the catalyst were added, a yellow solution was formed. With the addition of deionized water, the yellow color disappeared and the solution bubbled violently. This is because any unreacted acetic anhydride reacted with water which in turn caused the color to disappear. The addition of more water turned the solution white as precipitate came out of solution. The crude product was white powdery crystals that looked similar to flour. Recrystallization of this crude product resulted in white, shiny, and flaky crystals. The percent yield of acetylsalicylic acid was This low percent yield may have been caused material being lost in transfers and recrystallization. Additionally, the purified acetylsalicylic acid was used in melting point tests, solubility tests, and phenol tests, further lowering the percent yield. The melting point for acetylsalicylic acid was The literature melting point is The melting point for commercial aspirin was The melting points were quite close but the reason that purified acetylsalicylic acid had a lower melting point could be due to the presence of unreacted salicylic acid which would cause melting point depression. Although containing organic binders, the commercial aspirin was right on par with the literature melting point. Solubility tests were performed for the commercial and purified products. For the purified product, in toluene and hot water, it was slightly soluble. When the solutions were cooled and rubbed more solid was present in the water. In sodium hydroxide, it was insoluble until hydrochloric acid was added. For the tablet, it was soluble in toluene and insoluble in hot water. The reason the commercial aspirin was more soluble could be due to the organic binders. A ferric chloride test was used to identify the presence of phenols. In salicylic acid, the solution turned dark purple. This indicated the presence of phenol groups. For the crude and purified product in water, they both turned light purple. This meant that there was a small amount of unreacted salicylic acid because there is no phenol group in the products. The purified product with HCl turned dark purple. This is because the HCl causes the acetylsalicylic acid to turn back into salicylic acid which has a phenol group.
Experiment 18 discussion aspirin
Course: Organic Chemistry Lab II (CHEM201401)
University: Boston College
