If you need this or any other sample, we can send it to you via email. ; Wagener, L.R. Weight of the dried, recrystallised aspirin, the expected yield of aspirin from the amount of salicylic acid, the percentage yield of dried, recrystalllised aspirin is measured. Warner, T. D. & Mitchell, J. A catalyst, 85% phosphoric acid, was added to this reaction in order to increase the reaction rate. ; Carless, J.E. The limiting reactant in this chemical reaction was salicylic acid, with acetic anhydride present in excess in order to react with any water produced during the reaction of the reactants improving the yield of aspirin. The percent yield of the aspirin obtained from my experiment is 46.3% yield. Your institution may already be a subscriber. The percent yield was about 76.7% whereas the temperature range is between 134.2 to 136.1 ÌŠÌŠC. Dielectric Constants of Some Organic Compounds Over A Wide Temperature Range, The theory melting point is 140 ÌŠC and the experiment melting point range is 134.2 ÌŠC to 136.1 ÌŠC. This difference in solubility at hot versus cold temperatures is essential for the recrystallisation process. The solution was vacuum filtered through a Buchner funnel. Nierenstein, M., ; Shaw, P., The reactants in this chemical reaction most likely proceeded through undesired side reactions, despite the addition of a catalyst and DI water to react with excess acetic anhydride. If solid separates, warm till solid dissolved completely. Using thin-layer chromatography to investigate the reaction.....28 7. Why Management Is Important For Business Business Essay. [all data], Go To: Top, Normal melting point, References. The crude product aspirin prepared is relatively impure and may be purified by recrystallisation. This process yields aspirin and acetic acid (normally thought of as a byproduct). But not all 1.57g of the product is pure as the temperature falls slightly off the mark. However, our samples were most likely mainly compromised by the presence of water due to incomplete drying of our samples. Additional 40mL of cold water is added. The recrystallized aspirin yielded 1.399g and had a percent yield of 53.81%. A. Solvent suitable for this recrystallisation process is a mixture of ethanol and water. Salicylic acid reacts with acetic anhydride when an acid is present as a catalyst (In this experiment, sulfuric acid, H2sO4 was used as the catalyst.). 0000008513 00000 n [all data], Carswell, 1927 The median melting point temperature of the recrystallized aspirin was 131.5oC. with the development of data collections included in A. A fume hood is a large piece of equipment five enclosed sides of a work area, the bottom of which is most commonly located at a standing work height. Crystallization of Acetylsalicylic Acid, The mixture was stirred and rubbed with a stirring rod to induce crystallization. method, ground; Uncertainty assigned by TRC = 2. However, imprecise techniques, on account of the unskilled experimenters, led to an increase in the amount of materials lost beyond what was practically preventable. Assoc., 1927, 16, 306. (1.399g/2.6g) X 100 = 53.81% It is carried out to form ester from an acid and an alcohol. Komandin, A.V. The melting point range of pure aspirin is 138-140 C and the melting point range of the salicylic acid starting material is 158-161 C. If impurities are present in your crude sample, the melting point range Follow the links above to find out more about the data Recrystallization(Preparation of Recrystallized Aspirin) Amount of 95% ethanol added to crystals
%PDF-1.2 %���� This problem was magnified by the novice level of skill of the experimenters which increased loss beyond what could have been attainable. o-Acetylsalicylic acid Manufacturer; In stock GMP Factory, ACETYLSALICYLIC ACID, [CARBOXYL-14C],ACETYLSALICYLIC ACID-CARBOXY-14C, OXALIC ACID BIS[2,4,5-TRICHLORO-6-(PENTYLOXYCARBONYL)PHENYL] ESTER, LD50 orally in mice, rats: 1.1, 1.5 g/kg (Hart), Aspirin your own paper. Then, determine the melting point of aspirin using necessary apparatus. Med. method, not ground; Uncertainty assigned by TRC = 2. This could be due to environmental conditions which the sample experienced, such as: inadequate stirring, insufficient application of heat and cold or just pure chance. J. Pharm. The dried crystal is weighed together with the filter paper and watch glass. [all data], Summers, Carless, et al., 1970 Another important observation is that synthesis techniques that increase the purity of a sample also lead to a decrease in percent yield. The aspirin crystals began to form during this period. 20mL This tells me that the sample that I had gotten at the end of the experiment was quite pure and thus, close to the expected result instead. Constitution of Tannins,
; Herron, C.S.,
in these sites and their terms of usage. 143 0 obj << /Linearized 1 /O 145 /H [ 647 817 ] /L 183552 /E 8744 /N 34 /T 180573 >> endobj xref 143 11 0000000016 00000 n The purity of our crude and recrystallized aspirin samples were quantitatively measured by determining their respective melting point temperature ranges. [all data], Mulley, Rye, et al., 1971 Aspirin is a very important medicine and has been around since 1900 when Felix Hoffman and Friedrich Bayer and Company invented it. K; by differential thermal analysis Concludes that various m.p. New York: John Wiley & Sons. This solution was mixed thoroughly and then allowed to cool. following TRC products: El-Banna, 1978 But further analysis would have to be done to prove the exact purity of it. Therefore, according to my results, the aspirin obtained is relatively impure. The crystals filter paper and watch glass was to b dried in the oven for 15-20 minutes. [all data], Schwartzman, 1972 Experimental Percent Error 126oC-132oC(Median Temp: 129oC)
The extent of precipitation of the solid depends on the difference in its solubility in the particular solvent at temperatures between the extremes used. Almost all solids are more soluble in a hot than in a cold solvent, and solution crystallization takes advantage of this fact. From this experiment, I have learnt how to carry out suction filtration in the right way and to be cautious at all time when handling chemicals and so on. The major experimental findings are that, accuracy and attentiveness is very important in this experiment to obtain aspirin that is pure. 0000001442 00000 n 0000002068 00000 n The percentage yield is calculated. Experimental Organic Chemistry. The crude product was dissolved in approximately 5ml of ethanol in a 100ml conical flask. DI water added to solution while on hotplate Boca Raton, Fl: CRC Press, Taylor & Francis Group.