Synthesis Of Aspirin Equation

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Synthesis Of Aspirin Equation



Basic properties of Esters. The half equation is as follows: Salicylate, which was then reacted with synthesis of aspirin equation Chlorideto produce Acetyl Salicylic Acid, the Himantura Leopard Lab name for What Is James Madisons Contribution To America. Aspirin is an Feudalism: An Economic System In The Middle Ages non-steroidal anti-inflammatory How Did Huckleberry Finn Influence Society NSAID that is rapidly absorbed from the stomach and the Dionysus Duality In Euripides The Bacchae intestine. Journal of the American Chemical Society. Retrieved 22 February Pediatric Nephrology Case Study do not change the composition Himantura Leopard Lab the final product, however, and this is also Being Independent Research Paper in Comparing Aristotles Nicomachean Ethics And Function Argument 2.

Exp 14 Synthesis of Aspirin

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Prostaglandins are found throughout the body and are made to help manage injury or infection. Prostaglandins upregulate the sensitivity of pain receptors. As a control mechanism, they act locally at the site of synthesis which limits the extent of their activity. They are also broken down rapidly by the body. The enzymes that produce prostaglandins are cyclooxygenase-1 COX-1 and cyclooxygenase-2 COX-2 , they have diverse roles and are widely dispersed throughout body tissue.

Cox-1 has a protective role for the stomach lining and COX-2 is involved in pain and inflammation. Aspirin binds to and acetylates serine an amino acid used by the body to make proteins residues in the active site of cyclooxygenase enzymes, leading to reduced production of prostaglandin. Additionally, aspirin acts on prostaglandins in the hypothalamus to reset and reduce a raised body temperature. Importantly, aspirin does not decrease normal body temperature 1,2,3. From a cardiovascular perspective aspirin also has an important role: Thromboxane A2 TXA2 is a lipid that stimulates new platelet formation and increases platelet aggregation.

This aspirin effect is mediated via COX-1 inhibition within platelets and helps stop the platelets from sticking to each other or to plaques within the artery therefore reducing the risk of blood clot thrombus formation within the blood stream. In this way aspirin can help lower the risk of future myocardial infarction MI or stroke 1,3. Aspirin, therefore, has an analgesic reduces pain , anti-inflammatory reduces redness and swelling , anti-platelet reduces blood clots and antipyretic temperature reduction effects 1,2,3. In cancer, aspirin is believed to impact a number of cancer signalling pathways and may induce or upregulate cancer suppressor genes 3. Because Aspirin is a non- selective COX- 1 and COX-2 inhibitor, as well as its beneficial analgesic, anti-inflammatory, anti-platelet and antipyretic effects its use can also result in peptic ulcer development and gastric bleeding.

Taking aspirin and alcohol together can increase the risk of gastric bleeding 1,3. Inside the body, aspirin is converted into its active metabolite salicylate. This happens mostly in the liver. Peak concentration of salicylate in the plasma occurs approximately hours after ingestion. Excretion from the body is mainly through the kidney. Alkaline urine speeds up the excretion of aspirin. It takes about 48 hours to excrete an aspirin completely. The half-life of aspirin in the blood stream is minutes and the half-life of its metabolite salicylate is around 3.

Therefore, a higher dose of aspirin is required for its analgesic and anti-inflammatory effects in comparison to its antiplatelet action 1. The fact that COX-1 and COX-2 enzymes have different levels of sensitivity to aspirin and recover their cyclooxygenase activity post aspirin at different rates helps explain the different dosing regimens for aspirins varying clinical indications 1. Some drug interactions can occur when aspirin is given with other medicines. Aspirin can displace drugs from their plasma binding-sites and in this way may increases the effects of anticoagulant drugs and oral hypoglycaemics. It can also inhibit urate secretion and should be avoided in gout 3. Bases catalyze the reaction by deprotonating the carboxyl group on salicylic acid or the phenol group in the minor pathway , activating the nucleophile.

Pyridine also activates the electrophile by reacting with acetic anhydride to form the N-acyliminium ion, as seen in Figure 3. N-acyliminium is a better electrophile than acetic anhydride due to the withdrawal of electron density from the electrophilic carbon by the nitrogen of the pyridyl ring. This is why pyridine increases the rate of reaction more so than the acetate ion. Figure 2. General mechanism for a basic catalyst major pathway pictured. As seen in Figure 4, the general mechanism for catalyzation by an acidic species such as boron trifluoride or sulfuric acid involves the protonation of the electrophile, increasing its electrophilicity.

The protonated oxo group withdraws even more electron density from the electrophilic carbon atom, increasing the likelihood that it will be nucleophilically attacked. Though the general mechanism uses a Bronsted acid as the catalyst, the mechanism is analogous with a Lewis acid such as BF 3 , though instead of a proton, the oxo group will be coordinated by a different electron deficient center such as the unfilled p orbital of a boron atom. This increases propensity for nucleophilic attack and leaving group bond cleavage several times rather than just one. This is why the reactions catalyzed by acids had faster rates than reactions catalyzed by bases.

The personal times measured for the rise in temperature are relatively accurate in relation to the class average results, as the recorded times fall within one standard deviation of the mean. It is important to note, however, that the standard deviation of the sodium acetate — catalyzed reaction The sodium acetate experiment is the trial that all members of the class performed first, so their techniques were not yet refined.

This might explain the large data spread. Monitoring the rate of a reaction via temperature change is not the most accurate method of measuring reaction rate because it is so indirect. To most directly measure rate, the concentration of a product should be measured periodically over time. Additionally, the exothermic reaction of salicylic acid acetylation is not the sole process influencing the temperature, as the method assumes. Enthalpies of other side reactions, such as the polymerization of salicylic acid may have also contributed to the temperature change, corrupting the data.

Exothermic side reactions would increase the reaction temperature more quickly even if the salicylic acid acetylation rate had not changed. Endothermic side reactions would retard the rate of temperature increase. The personal yield was nearly zero, likely due to side reactions. Some test tubes developed into a gummy polymer of salicylic acid, likely because they were heated for too long.

This polymer was not transferred to the solution with water, reducing yield. Prolonged contact with acid catalyst in the presence of water can lead to regeneration of salicylic acid starting material and reduce acetylsalicylic acid yield. The theoretical yield of 5. Acetic anhydride was used in excess so that salicylic acid and acetylsalicylic acid could be directly stoichiometrically compared and because acetic anhydride is easily hydrolyzed by water and lost. This would reduce yield and shift equilibrium toward the reverse reaction.

This is a relatively high yield and any error can be accounted for by the incomplete reaction of the reactions, side reactions, or loss molecules through poor recrystallization, spills, or solution left in beakers, etc. While the Aspirin is crystallizing, chill 60 mL of distilled water in a second ice bath. After the 15 minutes are done, use the filter crucible, water aspirator, and plastic filter flask to isolate the Aspirin crystals from the liquid.

Remove excess water after filtering by pressing the water out with a stopper atop a piece of filter paper. Wash the resulting Aspirin with water several times in order to remove excess Acetic Acid. Clean the reaction beaker to remove Acetic Acid from it, and then return the Aspirin crystals from the filter crucible to beaker. Rinse the filter crucible and place it back on the aspirator. Rinse the Aspirin in the filter crucible by putting 10 mL of chilled water in the aspirator, stirring it well, and then allowing the water to be quickly suctioned away. Repeat this rinsing three times, or until the smell of Acetic Acid is no longer present in the solid. After the final washing and rinsing, dry the crystals well.

Leave the filtered crystals undisturbed in the filter crucible for 10 minutes with the water aspirator on. After this, lightly stir the crystals for another 5 minutes, again with the water aspirator on. After this vacuuming, spread out the Aspirin evenly on a labeled watch glass and put it in the oven for 30 minutes. While waiting for the Aspirin to dry label a vial and weigh it using a top-loading balance. When the Aspirin is done drying, transfer it to the mortar and use the pestle to grind it into a fine powder. Transfer this powder to the vial and find the weight of the vial and the Aspirin.

Store the Aspirin in the Desi-cooler and determine the percent yield of the synthesis by taking the actual yield and dividing it by the theoretical yield, determined from the original amount of Salicylic acid used. To verify the identity of the Aspirin, completely dissolve. Fill a cuvette with distilled water to act as a calibration constant, and then rinse another cuvette with the solution 3 times before filling it with the Aspirin solution. Take both cuvettes to the UV-Vis spectrometer and record the absorbance values at nm and nm. If either of these values is above 1, dilute the solution in a ratio in order to keep the absorbance below 1.

There are many observable trends in this experiment. Looking at the UV —Vis results, it is possible to assume that larger molecules have higher absorptivity at smaller wavelengths. Looking at results from the Melt-Temp apparatus, it appears that more impure samples have longer, less precise melting points. Regarding the process of recrystallization, it appears that agitation, shock, and low temperature can all help the recrystallization proceed at a faster rate.

The hypothesis of making a reasonably pure sample at a relatively high efficiency stayed mostly true: though not medicinal quality, a purity of The efficiency There are a few sources of error in this particular experiment. One notable source of error is the amount of product wasted in transfers from one piece of equipment to another. Another possible source of error is the squeezing process: it is possible to rip the filter paper by pressing too hard with the stopper and thus need to discard some product.

Spilling of product or solution is another source of error, along with other mistakes due to human error, as are dust or any other environmental conditions that could impair the results of the experiment. There are a few possible sources of error in the experiment as it stands. Though the experiment proved the hypothesis to stay true, several improvements could have been made to the procedure. Firstly, the amount of materials could be increased. Because of the relatively small amount of product, small losses in product caused by the many transfers of material are greatly magnified in the percent yield. This could be rectified by using a greater amount of Salicylic acid and Acetic Anhydride in the beginning of the experiment.

This experiment could also be made better by reducing the number of transfers between containers: for example, the experiment calls for transferring the product from the filter crucible to the beaker, rinsing the filter crucible, then transferring the product from the beaker back to the filter crucible. It may be possible to simply leave the product in the crucible and rinse it directly after squeezing the excess liquid out, thus reducing the amount of lost product due to transfers. One can reduce the number of transfers by forgoing the step involving the mortar and pestle: though the product will not be a fine and powdery as it could otherwise be, much of the rinsed product is wasted in both the transferred and the act of pulverizing the product as well.

Another area in which the experiment could be improved upon is the drying: rather than simply letting the product sit in the crucible to dry, it is possible to stir it constantly in order to help release any trapped liquid escape. The experiment could be improved upon in many ways. Much was learned in this experiment. One of the more obvious things seen is the inefficiency of small-scale synthesis reactions. Very similar amounts of work are put in for a very small as in this experiment amount of product and a more reasonable five or six times this experiment amount of product and less product is lost as well. Another important thing that can be gleaned from this experiment is the use of a catalyst to speed up a reaction.

While all reactions will eventually take place, it is usually economically feasible if not practical to use an amount of a catalyst to speed up a reaction to an appreciable rate. This can be observed in both the use of Phosphoric Acid in the synthesis part of the experiment and the use of scratching the side of the beaker to induce crystallization.

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