Preparation And Recrystallisation Of Aspirin Biology Essay

Preparation And Recrystallisation Of acetylsalicylic acid Biology EssayThe objective of this experiment is to enable us to understand and conduct the entailment of aspirin, understand the skills of recrystallisation and the technique of melting point closing. The main procedures are preparation of aspirin, recrystallisation of aspirin and lastly determining the melting point of the aspirin. For preparation of Aspirin, acetic anhydride is added to the measured amount of salicylic sultry. Sulphuric virulent is added and heated for a short period to complete reaction. Water is added once removed from heat with addition of cold weewee and sucking filtration is carried out. As for recrystallisation of aspirin, collected crude ware prepared in preparation of aspirin which is impure is turn in ethanol and hot distilled urine is added to the solution. The watch glass together with the get through paper was weighed and the weighed percolate paper was used to carry out the sucking filtration. Moreover, the crystals were send outs on the watch glass subsequently drying and its weight was calculated. Then, determine the melting point of aspirin using necessary apparatus. The percent end product was about 76.7% whereas the temperature range is between 134.2 to 136.1 C. The results are within the judge range and i would come together our experiment was a success.Felic Hoffman who is a german chemistry formed aspirin in 1897 by looking into French interpersonal chemistry Charles Gergardts experiment and rediscovered the acetylsalicylic acid and produced stable state of aspirin (The Great Idea Finder 2006). Salicylic acid was extracted from parts of willow trees (Dermaxime 2011).Aspirin is a derivative of salicylic acid that is a mild agent that stretchs pain by relieving headache and muscle and joint aches (History of aspirin 2011). Aspirin is likewise used to treat mild to mollify pain from conditions much(prenominal) as muscle aches, toothaches and hea daches. Aspirin works in our body by blocking certain natural substances in your body to reduce pain and swelling (Aspirin 2011). Esterification is a chemical reaction that is used to make esters in which the Carboxylic acid combines with an alcohol to form an ester CH3COOC2H5 in the presence of a catalyst which is usually concentrated sulphuric acid. It is reversible reaction and they produce sweet smelling products. Esters are widely used in fragrance and liveliness industry (Esterification reaction 2010). Aspirin has to be recrystallised several times to obtain purity. The properties that allow this to curb place is its bulky chemical group, solubility in weewee and its strong intermolecular forces between the aspirin molecules that allows it to make up the solid substance.ApplicationsAspirin crapper be used in various medical uses such as relieving mild aches and pains. It mickle alike be used for a little complex treatment such as hold onion of blood clots and prevent he art attack and stroke (Aspirin and Heart attacks 2005). However, there are side effects such as intimate bleeding to the stomach and other internal organs and also cause people to experience asthma attacks and undesirable swellings (Vitamin Diary, Aspirin 2010).TheoryEsterification ReactionFigure 1 Esterification Reaction (Preparation of Aspirin 1996)Shown in figure 1, is the esterification process. To form aspirin, Salicylic acid is reacted with acetic anhydride using sulphuric acid as a catalyst to produce Aspirin and Acetic acid. Sulphuric acid is used in this experiment as a catalyst to increase the rate of the reaction without being consumed in the process.Ethanoic AnhydrideThere are three reasons wherefore ethanoic anhydride is used rather than other reagents such as ethanoyl chloride even thou they outturn aspirin. The reasons are, ethanoic anhydride is cheaper to be purchased compared to ethanoyl chloride. It is also safer to use as it is less corrosive and does not readi ly hydrolyse in water unlike the other reagent. Moreover, it does not produce dangerous fumes of hydrogen chloride like ethanoyl chloride (Chemguide 2004).ProcedurePreparation of AspirinFirstly, approximately, 2.4g of salicylic acid was weighed into a dry coulombml conical flask and recorded. 6ml of acetic anhydride is added into the flask containing the salicylic acid in the fumehood. Then, 3-4 drops of concentrated sulphuric acid is added to the mixture and swirled. The mixture was also heated in the water bath for 10 to 15 minutes for the completing of reactions. afterwards removing the flask from the water bath, 1ml of distilled water is added using a eye dropper to decompose the excess acetic anhydride present in the solution. 40ml of cold water is added and is stirred and rub using a stirring rod to induce crystallisation. After suction filtration is carried out the crude product is and so collected.Re-crystallization of AspirinAn approximate 30ml of hot water is added to the solution and the crude product is dissolved in a 100ml conical flask with approximately 5ml of ethanol added to it and change on a hot plate. As there is solid separating out, the solution will be warmed till it is completely dissolved in the solution and was then allowed to cool. Then, a clean, dry watch glass with 2 filter written document was weighed and recorded. During the suction filtration of the solution, the recrystallised product is collected to the filter paper and was transferred to the watch glass. This was then put into the oven at 100oC for 15 20 minutes. Crystals together with the filter paper and the watch glass was then placed into desiccator for 5 to 10 minutes for all the liquid present to be drained. The dry out crystals together with the filter papers and watch glass was weighed and recorded. The weight of dried, recrystallised aspirin is then calculated. The expected output of aspirin was calculated from the amount of aspirin used and the percentage h and over of the dried, recrystallised aspirin was calculated.Melting point determination of aspirinThe aspirin was packed into the belittled capillary tubes and put into the optimelt melting apparatus to determine the melting temperature of Aspirin.ResultsMassMass of salicylic acid weighed (a) = 2.40gMass of filter paper watch glass (b) = 32.96gMass of dried, recrystallised aspirin, filter paper watch glass (c) = 34.41gMass of dried, recrystallised aspirin (d) is calculated by taking the mass of dried, recrystallised aspirin, filter paper and watch glass (c) which is 34.41g and subtract away the mass of filter paper and watch glass (b) which is 32.96g.(d) = (c) (b)= 34.41g 32.96g= 1.45gTherefore the mass of dried, recrystallised aspirin is 1.45g.Percent goTo obtain the percent yield of aspirin, we gift to find the moles of salicylic acid used first by taking the mass of the salicylic acid which is 2.40g and divide by the mr of salicylic acid. lean of moles of salicylic acid u sed (e) = mass/mr= 2.40/138= 0.017391 mol(mol wt of salicylic acid = 138)Therefore the expected number of moles of aspirin (f) = 0.017391 molTo calculate the expected mass of aspirin, we arrest to take the expected moles (f) which is 0.017391 mol multiply by the mr of aspirin 180.Expected mass of aspirin (g) = 0.01739 x 180 = 3.1302 g(mol wt = 180)Then the percent yield can be calculated by taking the mass of dried recrystallised aspirin (d) which is 1.45g and divide by the expected mass of aspirin 3.1302g multiply by 100%.Percent yield = (d) / (g) - 100%= 46.3%4.3 Melting PointTemperature range = 134.2 C to 136.1 C4.4 AppearanceWhite, thin, flaky crystals formed.DiscussionMy ResultsAccording to my experiment and the results, i conclude that my end product is not really pure. This can be seen from the calculation made based on my experiment using this formula,Percent yield = (mass of dried recrystallised aspirin / expected mass of aspirin) x 100%Percent yield is the amount of subst ance we have obtained in total in the experiment. The experimental yield percentage is different from the theoretical percentage is because there is loss of product often occurring during the isolation and purification steps (The Synthesis of Aspirin 2010). The percent yield of the aspirin obtained from the experiment is 46.3% yield. The higher the yield percentage, the higher the purity of the aspirin will be. Therefore, check to the results, the aspirin obtained is relatively impure. However, the low percent yield can also mean that the reactant has not reacted completely or the reaction is not complete. However there is also another possibility for the lower percent yield value. It is the addition of water when carrying out suction filtration. As we have to wash down the crystals before we carry out the suction filtration, close to crystals expertness have dissolved. Hence, the amount of water we use to wash down the crystals during suction filtration might have disturbed the percent yield too.The aspirin crystals are packed into the small capillary tubes and make sure they are all compressed without air gaps. Then they are placed into the melting apparatus. The melting temperature range of aspirin according to my experiment is between 134.2 C to 136.1 C. The theoretical melting temperature is 140 C. Since the range is near the theoretical value, this shows that the aspirin obtained is quite pure and hence contained fewer impurities.From both the calculations, I can evaluate that the aspirin is relatively pure to a however due to some experimental errors or improper techniques practiced, the percent yield is not up to expectation and to a greater extentover the incompletion of reaction might also be one of the reasons to the results obtained in this experiment.Experimental errorsThere were some experimental errors that have caused variation in my results compared to the theoretical solutions.Firstly, after the obtaining the crude product from the first suction filtration, we had to transfer it to the conical flask to carry out recrystallisation. During this process, there were some crystals that got blown away by the trend and some crystals poured on the desk too. Hence this might have affected the percent yield too.Therefore, I had learnt that all wind source must be switched off and be kept away from when carrying out this process to ensure accuracy in results.Secondly, once we have dissolved and during the second round suction filtration in attempt to obtain the pure aspirin, we forgot to use 2 filter papers but instead use just one filter paper on the Buchner funnel. Hence, due to the pressure, the filter paper tore and our crude product entered the filter flask that was containing the impurities and other liquid. Therefore we had to suction filtrate the whole mixture in the filter flask and hence, this might have led to presence of more impurities or lose in product. This might have affected the results.Figure 2 Apparatus o f suction filtration (Chemistry 104 Synthesis of Aspirin 2010)Therefore, from this experiment I learn that I must be more alert and careful when I carry out suction filtration to avoid unnecessary hassle and inaccuracy of results and calculation.ConclusionFrom 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 regard is very important in this experiment to obtain aspirin that is pure. However, there will be some environmental effects that will still affect the experiment to a small extent.Finally the objective of the experiment is met and the results were acceptable as it is quite accurate.RecommendationsTo improve on accuracy of results, we have to take into partake environmental factors such as the fan in the lab. It could affect the experimental findings as it blows away tiny light weight crystals while transferring them from one place to another. This would lead to loss of recrystallised crystals and cause variation in our calculations.When carrying out the suction filtration, it is strongly advisable to use 2 or more filter papers to prevent the tearing of the filter papers during the suction filtration due to the pressure. This would lead to the crystals to be in fall into place with lots of water and cause the crystals to dissolve. This might also cause inaccuracy to results. Moreover, when transferring the crystals into the Buchner flask before suction filtration, cold water is the most suitable to wash down the crystals as it minimises dissolving of crystals unlike fresh juvenile solvents.All the chemicals must be handles in the fumehood to prevent any corrosive chemicals such as salicylic acid, acetic anhydride and sulphuric acid to be in contact with our body. This is so as these chemicals can cause irritation to body parts such as eyes and skin and can also cause crowing burns.