Preparation And Recrystallisation Of Aspirin Biology Essay

Preparation And Recrystallisation Of acetylsalicylic acid Biology EssayThe objective of this try is to enable us to examine and conduct the synthesis of acetylsalicylic acerbicic, understand the skills of recrystallisation and the technique of melting point determination. The main procedures ar cookery of aspirin, recrystallisation of aspirin and lastly determining the melting point of the aspirin. For preparation of acetylsalicylic sour, acetic anhydride is added to the measured beat of salicylic acid. Sulphuric acid is added and heated for a short period to complete reaction. Water is added once removed from heat with access of cold water and suck filtration is carried proscribed. As for recrystallisation of aspirin, collected vulgar product prepared in preparation of aspirin which is impure is fade out in ethanol and alive distilled water is added to the solution. The come across chalk together with the trickle paper was weighed and the weighed filter paper was workd to engage out the suction filtration. Moreover, the crystals were places on the gull glass in after drying and its weight was calculated. therefore, determine the melting point of aspirin victimization necessary apparatus. The percentage soften was about 76.7% whereas the temperature range is between 134.2 to 136.1 C. The results are within the expected range and i would come to an end our experiment was a success.Felic Hoffman who is a german chemistry formed aspirin in 1897 by smell into French Chemistry Charles Gergardts experiment and rediscovered the acetylsalicylic acid and produced stable state of aspirin (The Great Idea scout 2006). Salicylic acid was extracted from parts of departow trees (Dermaxime 2011). acetylsalicylic acid is a derivative of salicylic acid that is a mild cistron that reduces pain by relieving headache and muscle and joint aches (History of aspirin 2011). aspirin is also used to discreetness mild to moderate pain from conditions su ch(prenominal) as muscle aches, toothaches and headaches. Aspirin works in our organic structure 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 brisk smelling products. Esters are widely used in fragrance and flavour industry (Esterification reaction 2010). Aspirin has to be recrystallised several quantifys to obtain purity. The properties that allow this to take place is its bulky chemical group, solubility in water and its strong intermolecular forces between the aspirin molecules that allows it to make up the solid substance.ApplicationsAspirin dismiss be used in various medical uses such as relieving mild aches and pains. It can also be used for a little complex t reatment such as barroom of blood clots and prevent heart attack and stroke (Aspirin and Heart attacks 2005). However, there are side do such as internal bleeding to the stomach and other internal organs and also constitute people to experience asthma attacks and undesirable swellings (Vitamin Diary, Aspirin 2010).TheoryEsterification chemical 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 why ethanoic anhydride is used rather than other reagents such as ethanoyl chloride even thou they yield 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 readily hydrolyse in water unlike the other reagent. Moreover, it does not produce dangerous fumes of hydrogen chloride like ethanoyl chloride (Chemguide 2004). appendagePreparation of AspirinFirstly, approximately, 2.4g of salicylic acid was weighed into a dry 100ml 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 categorization and swirled. The mixture was also heated in the water bath for 10 to 15 minutes for the completing of reactions. After removing the flask from the water bath, 1ml of distilled water is added using a dropper to decompose the excess acetic anhydride present in the solution. 40ml of cold water is added and is touched and rub using a stirring rod to induce crystallisation. After suction filtration is carried out the crude product is then collected.Re-crystallization of Aspiri nAn approximate 30ml of hot water is added to the solution and the crude product is turn in a 100ml conical flask with approximately 5ml of ethanol added to it and warmed on a hot plate. As there is solid separating out, the solution pull up stakes 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 dried crystals together with the filter papers and watch glass was weighed and recorded. The weight of dried, recrystallised aspirin is then calculated. The expected yield of aspirin was calculated from t he amount of aspirin used and the percentage yield of the dried, recrystallised aspirin was calculated.Melting point determination of aspirinThe aspirin was packed into the small 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 host of dried, recrystallised aspirin, filter paper and watch glass (c) which is 34.41g and subtract away the battalion 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. percentage YieldTo obtain the percent yield of aspirin, we have to find the moles of salicylic acid used starting by taking the mass of the salicylic acid which is 2.40g and divide by the m r of salicylic acid.Number of moles of salicylic acid used (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 have to take the expected moles (f) which is 0.017391 mol cypher 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 substance we have obtained in total in the experiment. The experimental yield percentage is different from the suppositious percentage is be motility 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, according 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 displace percent yield value. It is the addition of water when carrying out suction filtration. As we have to wash belt down the crystals before we carry out the suction filtration, nearly crystals might have dissolved. Hence, the amount of water we use to wash down th e crystals during suction filtration might have affected 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 thence contained fewer impurities.From both the calculations, I can evaluate that the aspirin is relatively pure to a tho due to some experimental errors or improper techniques practiced, the percent yield is not up to lookout and moreover 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 ob taining 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 wind 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 preferably use only one filter paper on the Buchner funnel. Hence, due to the pressure, the filter paper part 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 overleap in product. This migh t have affected the results.Figure 2 Apparatus of 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 attentiveness 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 concern environmental factors such as the fan in the lab. It could affect the experimental findings as it blows away tin y light weight crystals sequence 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 potently 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 contact 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 satisfactory to wash down the crystals as it minimises dissolving of crystals unlike fresh new 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 a nd can also cause bad burns.